transforming-growth-factor-alpha and Neoplasms

Abnormal regulation of cell signaling pathways on cell survival, proliferation and migration contributes to the development of malignant tumors. Among them, epidermal growth factor receptor (EGFR) is one of the most important biomarkers in many types of malignant solid tumors. Its over-expression and mutation status can be served as a biomarker to identify patients who can be benifit from EGFR tyrosine kinase inhibitors and anti-EGFR monocloncal antibody (mAb) therapy. For decades, researches on EGFR targeted ligands were actively carried out to identify potent candidates for cancer therapy. An ideal EGFR ligand can competitively inhibit the binding of endogenous growth factor, such as epidermal growth factor (EGF) and transforming growth factor-α(TGF-α) to EGFR, thus block EGFR signaling pathway and downregulate EGFR expression. Alternatively, conjugation of EGFR ligands on drug delivery systems (DDS) can facilitate targeting delivery of therapeutics or diagnostic agents to EGFR over-expression tumors via EGFR-mediated endocytosis. GE11 peptide is one of the potent EGFR ligand screened from a phage display peptide library. It is a dodecapeptide that can specifically binds to EGFR with high affinity and selectivity. GE11 has been widely used in the diagnosis and targeted delivery of drugs for radiotherapy, genetherapy and chemotherpy against EGFR positive tumors. In this review, the critical factors affecting the in vivo and in vitro targeting performance of GE11 peptide, including ligand-receptor intermolecular force, linker bond properties and physiochemical properties of carrier materials, are detailedly interpreted. This review provides a valuable vision for the rational design and optimization of GE11-based active targeting strategies for cancer treatment, and it will promote the translation studies of GE11 from lab research to clinical application.

Topics: Epidermal Growth Factor; ErbB Receptors; Humans; Ligands; Neoplasms; Peptide Library; Peptides; Protein Kinase Inhibitors; Transforming Growth Factor alpha

Recent advances in the field of cancer therapeutics come from the development of drugs that specifically recognize validated oncogenic or pro-metastatic targets. The latter may be mutated proteins with altered function, such as kinases that become constitutively active, or critical components of growth factor signaling pathways, whose deregulation leads to aberrant malignant cell proliferation and dissemination to metastatic sites. We herein focus on the description of the overlapping activities of two important developmental pathways often exacerbated in cancer, namely Transforming Growth Factor-β (TGF-β) and Hedgehog (HH) signaling, with a special emphasis on the unifying oncogenic role played by GLI1/2 transcription factors. The latter are the main effectors of the canonical HH pathway, yet are direct target genes of TGF-β/SMAD signal transduction. While tumor-suppressor in healthy and pre-malignant tissues, TGF-β is often expressed at high levels in tumors and contributes to tumor growth, escape from immune surveillance, invasion and metastasis. HH signaling regulates cell proliferation, differentiation and apoptosis, and aberrant HH signaling is found in a variety of cancers. We discuss the current knowledge on HH and TGF-β implication in cancer including cancer stem cell biology, as well as the current state, both successes and failures, of targeted therapeutics aimed at blocking either of these pathways in the pre-clinical and clinical settings.

Topics: Animals; Antibodies, Monoclonal; Antineoplastic Agents; Clinical Trials as Topic; Hedgehog Proteins; Humans; Neoplasms; Oligonucleotides, Antisense; Signal Transduction; Small Molecule Libraries; Transforming Growth Factor alpha

Overexpressed receptors, characteristic of many cancers, have been targeted by various researchers to achieve a more specific treatment for cancer. A common approach is to use the natural ligand for the overexpressed receptor as a cancer-targeting agent which can deliver a chemically or genetically conjugated toxic molecule. However, it has been found that the therapeutic efficacy of such ligand-drug molecular conjugates can be limited, since they naturally follow the intracellular trafficking pathways of the endogenous ligands. Therefore, a thorough understanding of the intracellular trafficking properties of these ligands can lead to novel design criteria for engineering ligands to be more effective drug carriers. This review presents a few commonly used ligand/receptor systems where intracellular trafficking considerations can potentially improve the therapeutic efficacy of the ligand-drug molecular conjugates.

Topics: Antineoplastic Agents; Biological Transport, Active; Biomedical Engineering; Diphtheria Toxin; Doxorubicin; Drug Carriers; Epidermal Growth Factor; ErbB Receptors; Exotoxins; Folic Acid; Folic Acid Transporters; Humans; Interleukin-13; Ligands; Models, Biological; Neoplasms; Receptors, Interleukin-13; Receptors, Transferrin; Ricin; Signal Transduction; Transferrin; Transforming Growth Factor alpha

Our previous study revealed that LYP, a bestatin dimethylaminoethyl ester, inhibited the growth of human ovarian carcinoma ES-2 xenografts in mice and suppressed aminopeptidase N (APN/CD13) activity more potently than bestatin. In this study, we examined the inhibitory effect of LYP on migration and formation of capillary tube of human umbilical vascular endothelial cells (HUVECs) in vitro and anti-angiogenesis in ES-2 xenografts in mice. LYP did not possess cytotoxicity to HUVEC proliferation according to the MTT assay and trypan blue exclusion assay. However, APN/CD13 activity on cell surface of HUVECs was suppressed in the presence of LYP as measured by quantifying the enzymatic cleavage of the substrate l-leucine-p-nitroanilide. The assays of scratch and transwell chamber showed that LYP significantly inhibited HUVEC migration and invasion through Matrigel coated polycarbonate filters. Capillary tube formation assay revealed that the number of branch points formed by HUVECs on 3-D Matrigel was reduced after incubation with LYP. The anti-angiogenesis of LYP was verified in ES-2 xenografts in mice. The mean vascular density (MVD) and mean vascular luminal diameter (MVLD) were markedly reduced by LYP after two weeks of intravenous injection as evaluated by CD34 immunohistochemical staining. LYP suppression of cancer angiogenesis was greater than that of bestatin. The inhibition of angiogenic molecules may involve in anti-angiogenesis of LYP. The levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and transforming growth factor-alpha (TGF-α) were decreased in HUVECs and ES-2 xenografts after treatment with LYP as determined by Western blot analysis. These results indicated that the high efficacy of LYP may partially relate to the inhibition of angiogenesis.

Topics: Angiogenesis Inhibitors; Animals; CD13 Antigens; Cell Membrane; Endothelium, Vascular; Esters; Fibroblast Growth Factor 2; Humans; Leucine; Mice; Neoplasm Transplantation; Neoplasms; Neovascularization, Pathologic; Transforming Growth Factor alpha; Umbilical Veins; Vascular Endothelial Growth Factor A

Transforming growth factor-alpha (TGFalpha) is a member of the epidermal growth factor (EGF) family. Expression of TGFalpha is highly regulated in response to exogenous cellular signals including cytokines and other growth factors. The growth factor has been found to be indispensable for proper development of many tissues and organs. TGFalpha has also been implicated in numerous disease states including forms of breast cancer. This minireview summarizes the basic biology of TGFalpha and its actions during normal and pathogenic development of the mammary epithelium.

Topics: Animals; Disease; Humans; Mammary Glands, Animal; Mice; Neoplasms; Transforming Growth Factor alpha

The unfortunate ability of tumor cells to survive and expand in an uncontrolled manner has captivated the attention of clinicians and basic scientists alike. The molecular mechanisms that tumor cells use to grow are the very same pathways used in normal cell growth and differentiation. One important pathway conferring a growth advantage on tumor cells is the epidermal growth factor receptor (EGFR) pathway. Signaling through the EGFR leads to activation of the phosphatidylinositol 3-kinase and Akt pathway and to increased activity of multiple effectors, including hypoxia-inducible factors (HIFs), which are cellular transcription factors involved in environmental stress response. The target genes that HIF members stimulate that are relevant to tumor growth include transcriptional activators and repressors and cytokines and growth factors, as well as their receptors. In this Perspective, findings from several recent studies are discussed in terms of their effect on the signal transducers, target genes, and tumor properties that are ultimately affected during EGFR-stimulated HIF signaling in cancer cells.

Topics: Animals; Antineoplastic Agents; Apoptosis Regulatory Proteins; Aryl Hydrocarbon Receptor Nuclear Translocator; Basic Helix-Loop-Helix Transcription Factors; Carcinoma, Renal Cell; Cell Division; Disease Progression; Drug Design; ErbB Receptors; Gene Expression Regulation, Neoplastic; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Kidney Neoplasms; Mice; Mice, Knockout; Mice, Transgenic; Neoplasm Proteins; Neoplasms; Repressor Proteins; Signal Transduction; Transcription Factors; Transforming Growth Factor alpha; Vascular Endothelial Growth Factor A; von Hippel-Lindau Disease; Von Hippel-Lindau Tumor Suppressor Protein

The topic of this review is first to analyze in normal conditions the signal transduction pathways induced by members of the HER-ErbB receptor family and their ligands, and second, to decipher some deregulations occurring in various cancer types. As a result, new therapeutic opportunities will be mentioned.

Topics: ErbB Receptors; Humans; Neoplasms; Prognosis; Receptor, ErbB-2; Receptor, ErbB-3; Receptor, ErbB-4; Signal Transduction; Transforming Growth Factor alpha; Virus Physiological Phenomena

The activation of the epidermal growth factor receptor (REGF) participates in oncogenesis by inducing cell proliferation, cell mobility and angiogenesis, and inhibiting apoptosis. This activation might be due to numerous abnormalities, including increased expression of its ligand. Although based on retrospective analyses with no standard technique of evaluation, the level of REGF expression is a prognosis factor for several tumors. It appears to be an indicator of poor prognosis which might influence treatments in head and neck tumors, cancers of the cervix, oesophagus, bladder and ovary. Its prognostic value is not observed in non-small cell lung cancer and remains to be demonstrated in adenocarcinomas such as colorectal tumors and beast cancer. Because of its role in oncogenesis and its prognostic value, REGF might in the future become a therapeutic target.

Topics: Carcinoma, Squamous Cell; Epidermal Growth Factor; ErbB Receptors; Female; Humans; Male; Neoplasm Proteins; Neoplasms; Organ Specificity; Prognosis; Receptor, ErbB-2; Transforming Growth Factor alpha

The epidermal growth factor (EGF) family of peptides encodes several proteins that can function as growth factors. The EGF-like peptides, with the exception of proteins of the EGF-CFC subfamily, bind and activate tyrosine kinase receptors that belong to the erbB family. The EGF-like peptides are overexpressed in a majority of human carcinomas as compared with their nontransformed counterpart. By using different approaches, it has been shown that several different EGF-like peptides function as autocrine growth factors in carcinoma cell lines of different histological origin. Direct evidence that the EGF-like growth factors might function as transforming genes has been provided by in vitro and in vivo studies. In particular, the development of different transgenic mouse lines in which EGF-like growth factors have been overexpressed by means of tissue-specific or nonspecific promoters has provided invaluable information relating to their ability to function as dominantly transforming oncogenes. Cooperation of the EGF-like peptides with cellular protooncogenes in determining cell transformation has been demonstrated by using both in vitro and transgenic mice systems. Taken together, these data strongly suggest that the EGF-like peptides are involved in the pathogenesis of human carcinomas, and that they might represent suitable targets for novel therapeutic approaches.

Topics: Amphiregulin; Animals; Betacellulin; EGF Family of Proteins; Epidermal Growth Factor; Epiregulin; Glycoproteins; GPI-Linked Proteins; Growth Substances; Heparin-binding EGF-like Growth Factor; Humans; Intercellular Signaling Peptides and Proteins; Membrane Glycoproteins; Membrane Proteins; Neoplasm Proteins; Neoplasms; Neuregulins; Transforming Growth Factor alpha

The epidermal growth factor receptor (EGFR)-driven autocrine growth pathway has been implicated in the development and progression of the majority of the most common human epithelial cancers, making the blockade of this growth pathway a promising anticancer therapeutic strategy. Different approaches have been developed to block EGFR activation and/or function in cancer cells. In the past 15 years, various anti-EGFR blocking monoclonal antibodies (MAb), recombinant proteins containing transforming growth factor-alpha (TGFalpha) or EGF fused to toxins, and tyrosine kinase inhibitors (TKIs) have been generated and their biological and potentially therapeutic properties characterised. One of these agents, MAb IMC-C225, a chimeric human-mouse IgG1 MAb, is the first anti-EGFR agent to enter phase II to III clinical trials in patients with cancer. Several small compounds that block the ligand-induced activation of the EGFR tyrosine kinase have been developed. Among these EGFR-TKIs, various quinazoline-derived agents have been synthesised and have shown promising activity as anticancer agents in preclinical models. ZD1839 ('Iressa'), an anilinoquinazoline, is an orally active, selective EGFR-TKI which is currently under clinical evaluation in phase II to III clinical trials in patients with cancer. Preclinical data for ZD1839 strongly support the possibility of potentiating the antitumour activity of conventional chemotherapy with agents that selectively block the EGFR.

Topics: Administration, Oral; Antibodies, Monoclonal; Antineoplastic Agents; Disease Progression; ErbB Receptors; Gefitinib; Humans; Ligands; Neoplasms; Protein-Tyrosine Kinases; Quinazolines; Signal Transduction; Transforming Growth Factor alpha

Recent technological advances, together with the discovery of the important role many growth factors play in modulating cell proliferation and differentiation, have led to the development of novel therapeutic agents for the treatment of cancer. In particular, advances in hybridoma technology and molecular engineering have permitted the development of humanized or chimeric monoclonal antibodies capable of interfering with growth factor signaling pathways. One promising target of interest is the epidermal growth factor receptor (EGFr), which is activated by the ligands EGF and TGF-alpha. This ligand receptor interaction plays a crucial role in the growth and survival of many human cancers. A chimeric (human/mouse) monoclonal antibody p6tuximab (IMC-C225) targets the EGFr and has potential clinical value as an anticancer agent.

Topics: Animals; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Cell Division; Cell Survival; Cetuximab; Clinical Trials as Topic; Epidermal Growth Factor; ErbB Receptors; Humans; Mice; Neoplasms; Protein Engineering; Recombinant Fusion Proteins; Signal Transduction; Transforming Growth Factor alpha

Peptide growth factors regulate normal cellular proliferation and differentiation through autocrine and paracrine pathways and are involved in cancer development and progression. Among the endogenous growth factors, the epidermal growth factor (EGF)-related proteins play an important role in the pathogenesis of human cancer. In fact, overexpression of EGF-related growth factors such as transforming growth factor alpha and amphiregulin and/or their specific receptor, the EGF receptor (EGFR), has been detected in several types of human cancers, including breast, lung, and colorectal cancers. Therefore, the blockade of EGFR activation by using anti-EGFR monoclonal antibodies (MAbs) has been proposed as a potential anticancer therapy. The cAMP-dependent protein kinase (PKA) is an intracellular enzyme with serine-threonine kinase activity that plays a key role in cell growth and differentiation. Two PKA isoforms with identical catalytic (C) subunits but different cAMP-binding regulatory (R) subunits (defined as RI in PKAI and RII in PKAII) have been identified. Predominant expression of PKAII is found in normal nonproliferating tissues and in growth-arrested cells, whereas enhanced levels of PKAI are detected steadily in tumor cells and transiently in normal cells exposed to mitogenic stimuli. Overexpression of PKAI has been correlated recently with poor prognosis in breast cancer patients. Inhibition of PKAI expression and function by specific pharmacological agents such as the selective cAMP analogue 8-chloro-cAMP (8-Cl-cAMP) induces growth inhibition in various human cancer cell lines in vitro and in vivo. We have provided experimental evidence of a functional cross-talk between ligand-induced EGFR activation and PKAI expression and function. In fact, PKAI is overexpressed and activated following transforming growth factor alpha-induced transformation in several rodent and human cell line models. Furthermore, PKAI is involved in the intracellular mitogenic signaling following ligand-induced EGFR activation. We have shown that an interaction between EGFR and PKAI occurs through direct binding of the RI subunit to the Grb2 adaptor protein. In this respect, PKAI seems to function downstream of the EGFR, and experimental evidence suggests that PKAI is acting upstream of the mitogen-activated protein kinase pathway. We have also demonstrated that the functional interaction between the EGFR and the PKAI pathways could have potential therapeutic implications. In f

Topics: 8-Bromo Cyclic Adenosine Monophosphate; Antibodies, Monoclonal; Antineoplastic Combined Chemotherapy Protocols; Cell Transformation, Neoplastic; Cyclic AMP-Dependent Protein Kinases; ErbB Receptors; Genes, ras; Humans; Neoplasms; Transforming Growth Factor alpha

It is known that long-term withdrawal of choline from the diet induces hepatocellular carcinomas in animal models in the absence of known carcinogens. We hypothesize that a choline deficient diet (CD) alters the balance of cell growth and cell death in hepatocytes and thus promotes the survival of clones of cells capable of malignant transformation. When grown in CD medium (5 microM or 0 microM choline) CWSV-1 rat hepatocytes immortalized with SV40 large T-antigen underwent p53-independent apoptosis (terminal dUTP end-labeling of fragmented DNA; laddering of DNA in agarose gel). CWSV-1 cells which were adapted to survive in 5 microM choline acquired resistance to CD-induced apoptosis and were able to form hepatocellular carcinomas in nude mice. These adapted CWSV-1 cells express higher amounts of both the 32 kDa membrane-bound and 6 kDa mature form of TGF alpha compared to cells made acutely CD. Control (70 microM choline) and adapted cells, but not acutely deficient hepatocytes, could be induced to undergo apoptosis by neutralization of secreted TGF alpha. Protein tyrosine phosphorylation is known to protect against apoptosis. We found decreased EGF receptor tyrosine phosphorylation in acutely choline deficient CWSV-1 cells. TGF beta 1 is an important growth-regulator in the liver. CWSV-1 cells express TGF beta 1 receptors and this peptide induced cell detachment and death in control and acutely deficient cells. Hepatocytes adapted to survive in low choline were also resistant to TGF beta 1, although TGF beta 1 receptors and protein could be detected in the cytoplasm of these cells. The non-essential nutrient choline is important in maintaining plasma membrane structure and function, and in intracellular signaling. Our results indicate that acute withdrawal of choline induces p53-independent programmed cell death in hepatocytes, whereas cells adapted to survive in low choline are resistant to this form of apoptosis, as well as to cell death induced by TGF beta 1. Our results also suggest that CD may induce alterations (mutations?) in growth factor signaling pathways which may enhance cell survival and malignant transformation.

Topics: Animals; Apoptosis; Choline; Choline Deficiency; Diet; Epidermal Growth Factor; Humans; Neoplasms; Signal Transduction; Transforming Growth Factor alpha; Transforming Growth Factor beta; Tumor Suppressor Protein p53

Among the most important targets for chemopreventive intervention and drug development are deregulated signal transduction pathways, and protein tyrosine kinases are key components of these pathways. Loss of tyrosine kinase regulatory mechanisms has been implicated in neoplastic growth; indeed, many oncogenes code for either receptor or cellular tyrosine kinases. Because of its deregulation in many cancers (bladder, breast, cervix, colon, esophagus, head and neck, lung, and prostate), the epidermal growth factor receptor (EGFR) has been selected as a potential target for chemoprevention. Because growth factor networks are redundant, selective inhibition of signaling pathways activated in precancerous and cancerous cells should be possible. Requirements for specific EGFR inhibitors include specificity for EGFR, high potency, activity in intact cells, and activity in vivo. Inhibition of autophosphorylation is preferred, because it should result in total blockade of the signaling pathway. Inhibitors that compete with substrate rather than at the ATP-binding site are also preferable, because they are not as likely to inhibit other ATP-using cellular enzymes. Several classes of specific EGFR inhibitors have been synthesized recently, including structures such as benzylidene malononitriles, dianilinophthalimides, quinazolines, pyrimidines, [(alkylamino)methyl]-acrylophenones, enollactones, dihydroxybenzylaminosalicylates, 2-thioindoles, aminoflavones, and tyrosine analogue-containing peptides. A possible testing strategy for the development of these and other EGFR inhibitors as chemopreventive agents includes the following steps: (a) determine EGFR tyrosine kinase inhibitory activity in vitro; (b) evaluate EGFR specificity and selectivity (relative to other tyrosine kinases and other protein kinases); (c) determine inhibition of EGFR-mediated effects in intact cells; (d) determine inhibition of EGFR-mediated effects in vivo (e.g., in nude mouse tumor xenografts); and (e) determine chemopreventive efficacy in vivo (e.g., in the hamster buccal pouch or mouse or rat bladder).

Topics: Animals; Anticarcinogenic Agents; Chemoprevention; ErbB Receptors; Humans; Neoplasms; Protein-Tyrosine Kinases; Signal Transduction; Transforming Growth Factor alpha

The epidermal growth factor receptor (EGFR) is detected on many non-haematopoietic tissues and is frequently overexpressed in human tumors. With its ligand, TGF-alpha, it forms a well-defined autocrine growth loop. Several clinical approaches, using EGFR as a therapeutic target, are being investigated, particularly monoclonal antibodies combined with chemotherapy, and pharmacological inhibition of downstream components of the EGFR signaling pathway.

Topics: Animals; Antibodies, Monoclonal; ErbB Receptors; Gene Expression Regulation, Neoplastic; Humans; Neoplasms; Tissue Distribution; Transforming Growth Factor alpha

Topics: Animals; Humans; Neoplasm Invasiveness; Neoplasms; Prognosis; Transforming Growth Factor alpha; Transforming Growth Factor beta

The processes of cellular proliferation and progressive acquisition of a specialized phenotype show a remarkable degree of coordination that involves both intracellular programming and intercellular communication. One of the major incentives for studying factors that regulate the processes of cellular proliferation and differentiation is the recognition of their potential contribution to tumorigenesis. In normal cells, stimulatory and inhibitory events are believed to be under the control of growth factors and growth inhibitory factors, which are known to be protooncogene products. Growth regulatory mechanisms usually involve the binding of a growth factor to a specific receptor on the cell surface, which then through an intracellular biochemical cascade leads to cell division. The cell regulation pathways initiated by growth factors may be subverted at several distinct levels in cancer cells. Studies of oncogenes have shown that they may function as abnormal growth factors or abnormal receptors, induce expression of potential signal regulators or encode proteins which modulate gene transcription. The purpose of the present paper is to examine the role of growth factors, growth factor receptors and intracellular proteins involved in signal transduction (with particular regard to the epidermal growth factor receptor system) in the control of normal growth and differentiation, and their contribution to transformation and tumorigenesis. We also review the classical theories of neoplasia and various other models. Chemical carcinogenesis and Vogelstein-Lane model are presented.

Topics: Amino Acid Sequence; Cell Division; Cell Transformation, Neoplastic; Epidermal Growth Factor; ErbB Receptors; Genes, Tumor Suppressor; Growth; Growth Substances; Humans; Molecular Sequence Data; Neoplasm Metastasis; Neoplasms; Oncogenes; Phenotype; Receptors, Growth Factor; Signal Transduction; Transcription, Genetic; Transforming Growth Factor alpha

Topics: Animals; Cytochrome P-450 CYP1A2; Cytochrome P-450 Enzyme System; DNA Damage; ErbB Receptors; Estrogens; Female; Gene Expression Regulation; Liver; Male; Models, Biological; Neoplasms; Oxidoreductases; Polychlorinated Dibenzodioxins; Rats; Receptors, Aryl Hydrocarbon; Receptors, Estrogen; Transforming Growth Factor alpha

The role of balance of negative and positive autocrine growth factors in malignant progression is reviewed with an emphasis on transforming growth factor alpha (TGF-alpha) as a stimulating factor and transforming growth factor beta (TGF-beta) as an inhibiting factor. Evidence suggests that in normal cells TGF-alpha is down regulated in non-dividing or quiescent states in vitro. Tumor cells which have early stage characteristics as represented by poor clonal growth and poor tumorigenicity in athymic mice also show repression of TGF-alpha in non-dividing states. Progression of this phenotype is induced by uncontrolled low level expression of TGF-alpha by transfection with a constitutive expression vector for the polypeptide. Transfection of the unprogressed phenotype with a constitutive anti-sense vector for TGF-beta, also leads to tumor progression by repressing the autocrine negative TGF-beta activity normally expressed by these cells. Both the upregulation of TGF-alpha and the repression of TGF-beta generated in vivo progression without changing growth rates in vitro. Instead, clonality and ability to reenter the cell cycle from quiescence were increased. Thus, it is concluded that an autocrine balance of positive and negative factors is important for maintaining controlled re-entry into dividing states from non-dividing states and that disruption of this balance leads to malignant progression characterized by greater independence of the malignant cells from the control of exogenous growth factors.

Topics: Gene Expression Regulation, Neoplastic; Humans; Neoplasms; Transforming Growth Factor alpha; Transforming Growth Factor beta

The design and construction of a new class of recombinant therapeutic agents, receptor-specific cytotoxins, has occurred within the last 5 years. Development of a number of receptor-targeted fusion toxins has been based on a detailed understanding of the structure-function relationships of both diphtheria toxin and Pseudomonas exotoxin A, and availability of the nucleic acid sequences of each structural gene. A variety of fusion toxins in which the native receptor-binding domain of either diphtheria toxin or Pseudomonas exotoxin A has been genetically replaced with either a polypeptide hormone or growth factor have been constructed. These fusion toxins selectively intoxicate receptor-bearing cells in vitro and are active in a variety of animal model systems. DAB486IL-2, and IL-2 receptor targeted cytotoxin, is the first fusion toxin to be evaluated in patients. Phase I/II clinical trials have been performed in refractory leukemia/lymphoma, severe rheumatoid arthritis, and Type 1 diabetes. DAB486IL-2 has been administered to more than 200 patients, has been well tolerated, and has shown encouraging signs of potential efficacy in all three clinical indications. Thus, DAB486IL-2 represents a new class of targeted biological therapeutic response modifiers whose mode of action is based on selective elimination of target cells.

Topics: Clinical Trials as Topic; Diphtheria Toxin; Exotoxins; Humans; Immunotoxins; Interleukin-2; Neoplasms; Recombinant Fusion Proteins; Recombinant Proteins; Transforming Growth Factor alpha

Cancer remains the second most common cause of death in our society, and advanced disease is often refractory to surgical, chemotherapeutic, and radiologic interventions. One novel approach to cancer treatment involves targeting a cytotoxic agent to a cancer cell. Immunotoxins have been developed that contain a potent toxin (either Pseudomonas exotoxin, ricin toxin, or diphtheria toxin) coupled to a targeting moiety that directs the molecule to cells expressing a certain antigen. Chemically coupled immunotoxins have been developed over the past 12 years. These bind to and kill cells expressing many tumor-associated antigens. Initial clinical results were disappointing, but recent results have been more promising. Furthermore, newer immunotoxins have been developed that will soon be in clinical trials. Some of these are recombinant toxins that have been developed using techniques of genetic engineering. Transforming growth factor-alpha, acidic fibroblast growth factor, insulin-like growth factor-1, interleukin-2, interleukin-4, interleukin-6, the binding portions of monoclonal antibodies, and CD4 have been used to direct toxins to cancer cells or cells infected with the human immunodeficiency virus type 1. Efforts are under way to circumvent problems such as immunogenicity that may limit the clinical usefulness of immunotoxins.

Topics: ADP Ribose Transferases; Antibodies, Monoclonal; Bacterial Toxins; Exotoxins; Forecasting; Humans; Immunotoxins; Neoplasms; Pseudomonas aeruginosa Exotoxin A; Recombinant Proteins; Transforming Growth Factor alpha; Virulence Factors

Recombinant toxins which bind to growth factor receptors have been prepared and used to kill cells responsible for malignant or autoimmune disease. Our strategy has been to genetically fuse ligands to different forms of Pseudomonas exotoxin which due to mutations or deletions do not bind to normal cells. The resulting recombinant chimeric toxins, in concentrations often less than 1 ng/ml, selectively kill cells expressing the appropriate growth factor receptor. The ligand may be a growth factor, such as transforming growth factor alpha (TGF alpha), interleukin 6 (IL6) or interleukin 2 (IL2), or single chain antigen binding proteins, such as the variable heavy and light regions of the monoclonal antibody anti-Tac. These chimeric toxins kill not only established cell lines but also fresh tumor cells from patients and display anti-tumor activity toward human malignant tumors in nude mice. While clinical trials are beginning with some of these agents, work continues to improve the effectiveness of recombinant chimeric toxins, and to widen the scope of disorders which might be treated by this approach.

Topics: ADP Ribose Transferases; Bacterial Toxins; Cell Survival; Exotoxins; Humans; Immunotoxins; Interleukin-2; Interleukin-6; Interleukins; Neoplasms; Pseudomonas; Pseudomonas aeruginosa Exotoxin A; Receptors, Cell Surface; Recombinant Fusion Proteins; Transforming Growth Factor alpha; Tumor Cells, Cultured; Virulence Factors

This review considers the biology of the type 1 growth factor receptor family which is increasingly recognised as important in the control of normal cell proliferation and in the pathogenesis of human cancer. The family currently comprises three closely related members: the epidermal growth factor (EGF) receptor, c-erbB-2 and c-erbB-3, all of which show abnormalities of expression in various human tumours. The family of factors related to EGF has also expanded recently and now includes transforming growth factor alpha, heparin-binding EGF, amphiregulin, cripto and heregulin, as well as several other potential ligands for the c-erbB2-2 receptor. The involvement of these receptors and growth factors in human cancer has implications for the design of novel forms of therapy for cancer, and we review recent advances and future avenues for investigation.

Topics: Amino Acid Sequence; Amphiregulin; Animals; Base Sequence; Biomarkers, Tumor; Caenorhabditis; Consensus Sequence; Drosophila; Drosophila Proteins; EGF Family of Proteins; Epidermal Growth Factor; ErbB Receptors; Gene Expression Regulation; Gene Expression Regulation, Neoplastic; Glycoproteins; GPI-Linked Proteins; Growth Substances; Heparin; Heparin-binding EGF-like Growth Factor; Humans; Intercellular Signaling Peptides and Proteins; Ligands; Mammals; Membrane Glycoproteins; Molecular Sequence Data; Multigene Family; Neoplasm Proteins; Neoplasms; Proto-Oncogene Proteins; Proto-Oncogenes; Receptor, ErbB-2; Receptor, ErbB-3; Signal Transduction; Transforming Growth Factor alpha; Viral Proteins

Topics: Animals; Cell Transformation, Neoplastic; Enzyme Induction; ErbB Receptors; Gene Amplification; Genes; Humans; Mice; Mitosis; Multigene Family; Neoplasm Proteins; Neoplasms; Neoplasms, Experimental; Oncogene Proteins v-erbB; Oncogenes; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Proto-Oncogenes; Rats; Receptor, ErbB-2; Receptor, ErbB-3; Recombinant Fusion Proteins; Retroviridae Proteins, Oncogenic; Sequence Homology, Amino Acid; Transforming Growth Factor alpha

Topics: Animals; Clinical Trials as Topic; Colony-Stimulating Factors; Erythropoietin; Fibroblast Growth Factors; Growth Hormone; Growth Substances; Humans; Insulin-Like Growth Factor I; Interleukins; Neoplasms; Platelet-Derived Growth Factor; Recombinant Proteins; Transforming Growth Factor alpha; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha; Wound Healing

Topics: Amino Acid Sequence; Animals; Binding, Competitive; Cell Division; Cell Transformation, Neoplastic; Embryonic and Fetal Development; Epidermal Growth Factor; ErbB Receptors; Gene Expression Regulation, Neoplastic; Growth Substances; Humans; Membrane Glycoproteins; Mice; Molecular Sequence Data; Multigene Family; Neoplasm Proteins; Neoplasms; Protein Precursors; Protein Processing, Post-Translational; Rats; Signal Transduction; Transforming Growth Factor alpha

The capacity of growth factors to activate receptors through autocrine and paracrine pathways continues to be a major focus of cancer biology research. This review of growth factors for solid tumor cells complements our summary of hematopoietic growth factors.

Topics: Amphiregulin; Cell Differentiation; Cell Division; EGF Family of Proteins; Epidermal Growth Factor; ErbB Receptors; Glycoproteins; Growth Substances; Humans; Intercellular Signaling Peptides and Proteins; Neoplasms; Platelet-Derived Growth Factor; Proto-Oncogene Proteins; Receptor, ErbB-2; Receptors, Cell Surface; Receptors, Platelet-Derived Growth Factor; Sequence Homology, Nucleic Acid; Transforming Growth Factor alpha; Transforming Growth Factor beta; Tumor Cells, Cultured

Monoclonal anti-EGF receptor antibodies, EGF receptor antibodies coupled to toxins, TGF alpha-toxin conjugates and tyrosine kinase inhibitors show great potential as antitumor agents. These compounds are effective inhibitors of the EGF receptor system as it functions in the mitogenic stimulation of malignant cells. The effectiveness of cell growth inhibition mediated by anti-EGF receptor antibody and tyrosine kinase inhibitors may prove to be limited and selective. This is in view of the possibility that malignant cell proliferation may be controlled by various mechanisms instead of that which involves the EGF receptor system, despite the expression of both EGF receptor and TGF alpha in the same cell. Other growth control mechanisms could involve hormone receptor systems such as estradiol and the estrogen receptor, oncogene activation or other growth factor-receptor systems. In those malignancies in which growth control resides in the EGF-receptor system, antitumor therapy using monoclonal anti-EGF receptor antibodies and tyrosine kinase inhibitors is a possibility worth pursuing. The effectiveness of immunotoxins and TGF alpha-toxin conjugates may only require the presence of EGF receptor and not be limited to those cells whose growth is controlled exclusively by the EGF receptor system. Nonspecific toxicity may, however, limit the use of these compounds. Further studies assessing the extent of such a toxicity are in order. In the face of the preceding reservations, however, one must not overlook the potential for great achievement as this novel therapeutic avenue is traversed.

Topics: Animals; Antibodies, Monoclonal; Cell Division; Cell Transformation, Neoplastic; ErbB Receptors; Humans; Immunotoxins; Neoplasms; Protein-Tyrosine Kinases; Transforming Growth Factor alpha

Many types of cancer cells display aberrantly high numbers of EGF receptors on their surface. We have targeted these cells for elimination by combining the cell binding ability of either epidermal growth factor or transforming growth factor type alpha with the potent cell killing activity of Pseudomonas exotoxin. These chimeric molecules are formed either by chemical conjugation of the two proteins or by expression of a gene fusion into a product containing both proteins. In this review, we show that these chimeric toxins are extremely cytotoxic to a variety of cancer cell lines.

Topics: Cell Survival; Epidermal Growth Factor; Exotoxins; Humans; Immunotoxins; Neoplasms; Pseudomonas aeruginosa; Transforming Growth Factor alpha

Combined inhibition of epidermal growth factor receptor (EGFR) and Src family kinases (SFK) may lead to improved therapeutic effects. We evaluated the combination of dasatinib, an inhibitor of SFK and other kinases, and cetuximab, an anti-EGFR monoclonal antibody.. Patients with advanced solid malignancies received cetuximab intravenously on a standard weekly schedule and dasatinib orally, once daily at 3 dose levels: (1) 100 mg, (2) 150 mg, (3) 200 mg. Pharmacokinetic and pharmacodynamic studies of dasatinib were performed prior to starting cetuximab and following 14 days of treatment.. Twenty-five patients (3 dose level 1; 19 dose level 2; 3 dose level 3) were initially treated. Three patients developed dose-limiting toxicities: 1 at dose level 2 (headache) and 2 at dose level 3 (headache, nausea). Grade 3-4 toxicities in more than 2 patients included: dyspnea (4), vomiting (4), nausea (3), hypersensitivity reactions (3), headache (3) and anemia (3). Twenty-one patients developed headache (8 grade 1; 10 grade 2), which occurred after the loading of cetuximab and lasted 1-3 days. Six additional patients were treated with dasatinib starting 3 days after the loading dose of cetuximab; none developed headache after dasatinib. Dasatinib pharmacokinetics and a transient decrease in SFK PY416 levels in peripheral blood mononuclear cells were not altered by cetuximab. Patients with higher plasma TGF-alpha levels had worse progression-free survival.. Dasatinib 150 mg once daily plus weekly cetuximab is recommended for phase II studies. Early-onset headache was ameliorated by starting dasatinib after cetuximab.

Topics: Adult; Aged; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Cetuximab; Dasatinib; Disease-Free Survival; Dose-Response Relationship, Drug; Female; Humans; Male; Middle Aged; Neoplasm Staging; Neoplasms; Proto-Oncogene Proteins pp60(c-src); Pyrimidines; Thiazoles; Transforming Growth Factor alpha

The anticancer effects of arazyme, a bacterial metalloprotease, have been revealed in previous studies. Because of the overexpression of epidermal growth factor receptor (EGFR) in tumor cells, targeting this receptor is one of the approaches to cancer therapy. In the present study, we designed fusion protein by using a non-mitogenic binding sequence of TGFα, arazyme, and a suitable linker. The I-TASSER and Robetta web servers were employed to predict the territory structures of the Arazyme-linker-TGFαL3, and TGFαL3-linker-Arazyme. Then, models were validated by using PROCHECK, ERRAT, ProSA, and MolProbity web servers. After docking to EGFR, Arazyme-linker-TGFαL3 showed a higher binding affinity and was selected to be optimized through 100 ns Molecular dynamic (MD) simulation. Next, the stability of ligand-bound receptor was examined utilizing MD simulation for 100 ns. Furthermore, the binding free energy calculation and free energy decomposition were carried out employing MM-PBSA and MM-GBSA methods, respectively. The root mean square deviation and fluctuation (RMSD, RMSF), the radius of gyration, H-bond, and binding free energy analysis revealed the stability of the complex during simulation time. Finally, linear and conformational epitopes of B cells, as well as MHC class I and MHC class II were predicted by using different web servers. Meanwhile, the potential B cell and T cell epitopes were identified throughout arazyme protein sequence. Collectively, this study suggests a novel chimera protein candidate prevent cancer cells potentially by inducing an immune response and inhibiting cell proliferation. Communicated by Ramaswamy H. Sarma.

Topics: Cell Proliferation; ErbB Receptors; Molecular Docking Simulation; Molecular Dynamics Simulation; Neoplasms; Transforming Growth Factor alpha

Ectodomain shedding of cell-surface precursor proteins by metalloproteases generates important cellular signaling molecules. Of importance for disease is the release of ligands that activate the EGFR, such as TGFα, which is mostly carried out by ADAM17 [a member of the A-disintegrin and metalloprotease (ADAM) domain family]. EGFR ligand shedding has been linked to many diseases, in particular cancer development, growth and metastasis, as well as resistance to cancer therapeutics. Excessive EGFR ligand release can outcompete therapeutic EGFR inhibition or the inhibition of other growth factor pathways by providing bypass signaling via EGFR activation. Drugging metalloproteases directly have failed clinically because it indiscriminately affected shedding of numerous substrates. It is therefore essential to identify regulators for EGFR ligand cleavage. Here, integration of a functional shRNA genomic screen, computational network analysis, and dedicated validation tests succeeded in identifying several key signaling pathways as novel regulators of TGFα shedding in cancer cells. Most notably, a cluster of genes with NFκB pathway regulatory functions was found to strongly influence TGFα release, albeit independent of their NFκB regulatory functions. Inflammatory regulators thus also govern cancer cell growth-promoting ectodomain cleavage, lending mechanistic understanding to the well-known connection between inflammation and cancer.

Topics: Cell Line, Tumor; ErbB Receptors; Gene Regulatory Networks; Genomics; Humans; Jurkat Cells; Ligands; Models, Genetic; Neoplasms; RNA, Small Interfering; Signal Transduction; Transforming Growth Factor alpha

The epidermal growth factor receptor (EGFR) is activated through binding to specific ligands and generates signals for proliferation, differentiation, migration, and cell survival. Recent data show the role of nuclear EGFR in tumors. Although many EGFR ligands are upregulated in cancers, little is known about their effects on EGFR nuclear translocation. We have compared the effects of six EGFR ligands (EGF, HB-EGF, TGF-α, β-Cellulin, amphiregulin, and epiregulin) on nuclear translocation of EGFR, receptor phosphorylation, migration, and proliferation. Cell fractionation and confocal immunofluorescence detected EGFR in the nucleus after EGF, HB-EGF, TGF-α and β-Cellulin stimulation in a dose-dependent manner. In contrast, amphiregulin and epiregulin did not generate nuclear translocation of EGFR. EGF, HB-EGF, TGF-α and β-Cellulin showed correlations between a higher rate of wound closure and increased phosphorylation of residues in the carboxy-terminus of EGFR, compared to amphiregulin and epiregulin. The data indicate that EGFR is translocated to the nucleus after stimulation with EGF, HB-EGF, TGF-α and β-Cellulin, and that these ligands are related to increased phosphorylation of EGFR tyrosine residues, inducing migration of SkHep-1 cells.

Topics: Active Transport, Cell Nucleus; Betacellulin; Cell Line, Tumor; Cell Movement; Cell Nucleus; Cell Proliferation; Epidermal Growth Factor; ErbB Receptors; Heparin-binding EGF-like Growth Factor; Humans; Neoplasms; Phosphorylation; Transforming Growth Factor alpha

The inhibition of the Ras/mitogen-activated protein kinase (Ras/MAPK) pathway through the suppression of mutated Ras or MAPK/extracellular signal-regulated kinase 1/2 (MEK1/2) has been shown to sensitize tumor cells to ionizing radiation (IR). The molecular mechanisms of this sensitization however, are not yet fully understood. In this study, we investigated the role of transforming growth factor-α (TGF-α) in the radiosensitizing effects of selumetinib, a selective inhibitor of MEK1/2. The expression of epidermal growth factor receptor (EGFR) ligands was assessed by ELISA in both Ras wild-type and Ras mutant cells that were exposed to radiation with or without selumetinib. The effects of selumetinib on the TGF-α/EGFR signaling cascade in response to radiation were examined by western blot analysis, clonogenic assay and by determing the yield of mitotic catastrophe. The treatment of cells with selumetinib reduced the basal and IR-induced secretion of TGF-α in both Ras wild-type and Ras mutant cell lines in vitro and in vivo. The reduction of TGF-α secretion was accompanied with a reduction in phosphorylated tumor necrosis factor-α converting enzyme (TACE) in the cells treated with selumetinib with or without IR. The treatment of cells with selumetinib with or without IR inhibited the phosphorylation of EGFR and checkpoint kinase 2 (Chk2), and reduced the expression of survivin. Supplementation with exogenous TGF-α partially rescued the selumetinib-treated cells from IR-induced cell death, restored EGFR and Chk2 phosphorylation and increased survivin expression. These data suggest that the inhibition of MEK1/2 with selumetinib may provide a mechanism to sensitize tumor cells to IR in a fashion that prevents the activation of the TGF-α autocrine loop following IR.

Topics: ADAM Proteins; ADAM17 Protein; Animals; Benzimidazoles; Cell Line, Tumor; Cell Survival; ErbB Receptors; Humans; Ligands; MAP Kinase Kinase 1; MAP Kinase Kinase 2; Mice; Mice, Nude; Mutation; Neoplasms; Protein Kinase Inhibitors; Proto-Oncogene Proteins; Proto-Oncogene Proteins p21(ras); Radiation Tolerance; Radiation-Sensitizing Agents; Radiation, Ionizing; ras Proteins; Signal Transduction; Transforming Growth Factor alpha; Xenograft Model Antitumor Assays

The epidermal growth factor receptor (EGFR) is frequently expressed in triple-negative breast cancer (TNBC) and is a marker of poor prognosis in this patient population. Because activating mutations in this kinase are very rare events in breast cancer, we screened breast tumor gene expression profiles to examine the distribution of EGFR ligand expression. Of the six known EGFR ligands, transforming growth factor alpha (TGFα) was expressed more highly in triple-negative breast tumors than in tumors of other subtypes. TGFα is synthesized as a transmembrane precursor requiring tumor necrosis factor alpha converting enzyme (TACE)/ADAM17-dependent proteolytic release to activate its receptor. In our study, we show that an inhibitor of this proteolytic release blocks invasion, migration and colony formation by several TNBC cell lines. Each of the effects of the drug was reversed upon expression of a soluble TGFα mutant that does not require TACE activity, implicating this growth factor as a key metalloproteinase substrate for these phenotypes. Together, these data demonstrate that TACE-dependent TGFα shedding is a key process driving EGFR activation and subsequent proliferation and invasion in TNBC cell lines.

Topics: ADAM Proteins; ADAM17 Protein; Breast Neoplasms; Cell Line, Tumor; ErbB Receptors; Female; Gene Expression Regulation, Neoplastic; Humans; Mutation; Neoplasm Invasiveness; Neoplasms; Phosphorylation; Signal Transduction; Transforming Growth Factor alpha

Tumor invasion is the outcome of a complex interplay between cancer cells and the stromal environment. Considering the contribution of the stromal environment, we developed a membrane-free single-cell and spheroid based complementary model to study cancer invasion through native collagen type-I matrices. Cell morphology is preserved during the assays allowing real time monitoring of invasion-induced changes in cell structure and F-actin organization. Combining these models with computerized quantification permits the calculation of highly reproducible and operator-independent data. These assays are versatile in the use of fluorescent probes and have a flexible kinetic endpoint. Once the optimal experimental conditions are empirically determined, the collagen type-I invasion assays can be used for preclinical validation of small-molecule inhibitors targeting invasion. Initiation and monitoring of the single-cell and spheroid invasion model can be achieved in 8 h (over 3 days) and in 14 h (over 8 days) respectively.

Topics: Actins; Cell Culture Techniques; Cell Line, Tumor; Cell Movement; Collagen Type I; Cytoskeleton; Extracellular Matrix; Fibroblasts; HCT116 Cells; HeLa Cells; HT29 Cells; Humans; Models, Biological; Myoblasts; Neoplasm Invasiveness; Neoplasms; Spheroids, Cellular; Time Factors; Transforming Growth Factor alpha; Tumor Cells, Cultured

Inappropriate expression of Ets-1 is observed in a variety of human cancers, and its forced expression in cultured cells results in transformation, autonomous proliferation, and tumor formation. The basis by which Ets-1 confers autonomous growth, one of the primary hallmarks of cancer cells and a critical component of persistent proliferation, has yet to be fully explained. Using a variety of cancer cell lines, we show that inhibition of Ets-1 blocks tumor formation and cell proliferation in vivo and autonomous growth in culture. A screen of multiple diffusible growth factors revealed that inhibition of Ets-1 results in the specific downregulation of transforming growth factor alpha (TGFalpha), the proximal promoter region of which contains multiple ETS family DNA binding sites that can be directly bound and regulated by Ets-1. Notably, rescuing TGFalpha expression in Ets-1-silenced cells was sufficient to restore tumor cell proliferation in vivo and autonomous growth in culture. These results reveal a previously unrecognized mechanism by which Ets-1 oncogenic activity can be explained in human cancer through its ability to regulate the important cellular mitogen TGFalpha.

Topics: Cell Growth Processes; Cell Line, Tumor; Cell Transformation, Neoplastic; Glioma; Humans; Kidney Neoplasms; Male; Neoplasms; Promoter Regions, Genetic; Prostatic Neoplasms; Protein Binding; Proto-Oncogene Protein c-ets-1; Transfection; Transforming Growth Factor alpha

Topics: Basic Helix-Loop-Helix Transcription Factors; Carcinoma, Renal Cell; ErbB Receptors; Humans; Kidney Neoplasms; Neoplasms; Receptor Protein-Tyrosine Kinases; Transforming Growth Factor alpha

Growth factors are implicated in several processes essential for cancer progression. Specifically, growth factors that bind to ErbB family receptors have been implicated in cell proliferation and in resistance of solid tumors to chemotherapy. We quantified ligand secretion by several human cancer cell lines, and generated mAbs against two ligands, namely TGF-alpha and heparin-binding EGF-like growth factor. These growth factors are frequently secreted by pancreatic tumor cell lines, including BxPC3 cells. The monoclonal antibodies were tested for their antigen specificity and ability to inhibit growth of BxPC3 cells in vitro. Combining the two antibodies resulted in enhanced inhibition of BxPC3 cell growth, both in vitro and in tumor-bearing animals. Hence, we combined the two antibodies with gemcitabine, an effective chemotherapeutic drug commonly used to treat pancreatic cancer patients. Because treatment with a combination of two monoclonal antibodies enhanced the ability of chemotherapy to inhibit BxPC3 tumors in mice, we propose a general cancer therapeutic strategy that entails profiling the repertoire of growth factors secreted by a tumor, and combining with chemotherapy several antibodies capable of blocking autocrine ligands.

Topics: Animals; Antibodies; Antibodies, Monoclonal; Antibody Specificity; Cell Line, Tumor; Cell Proliferation; Deoxycytidine; ErbB Receptors; Female; Gemcitabine; Heparin-binding EGF-like Growth Factor; Humans; Immunotherapy; Intercellular Signaling Peptides and Proteins; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasms; Pancreatic Neoplasms; Transforming Growth Factor alpha

The objective of this study was to characterize treatment-induced circulating ligand changes during therapy with epidermal growth factor receptor (EGFR) inhibitors and evaluate their potential as surrogate indicators of the optimal biological dose.. Conditioned medium from human tumor cell lines, ascites fluid from tumor xenografts, and plasma samples from normal mice, as well as colorectal cancer patients, were assessed for ligand elevations using ELISA, following treatment with cetuximab (Erbitux), an anti-mouse EGFR neutralizing antibody, or a small-molecule EGFR tyrosine kinase inhibitor.. A rapid elevation in human transforming growth factor alpha (TGF-alpha) was observed in all cell lines after treatment with cetuximab, but not with small-molecule inhibitors. The elevation showed a dose-response effect and plateau that corresponded to the maximal decrease in A431 proliferation in vitro and HT29 tumor growth in vivo. The TGF-alpha increase was exacerbated by ongoing ligand production and cleavage from the plasma membrane but did not involve transcriptional up-regulation of TGF-alpha or the matrix metalloproteinase tumor necrosis factor-alpha-converting enzyme/ADAM17. Elevations in plasma TGF-alpha, amphiregulin, and epiregulin were also detected in normal mice treated with an anti-mouse EGFR monoclonal antibody, illustrating a host tissue-dependent component of this effect in vivo. Finally, circulating TGF-alpha increased in the plasma of six patients with EGFR-negative colorectal tumors during cetuximab treatment.. Treatment-induced increases in circulating ligands, particularly TGF-alpha, should be serially assessed in clinical trials of anti-EGFR therapeutic antibodies as potential biomarkers to aid in determination of the optimal biological dose.

Topics: Animals; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Biomarkers; Cell Line, Tumor; Cell Proliferation; Cetuximab; Dose-Response Relationship, Drug; ErbB Receptors; Female; Humans; Ligands; Mice; Mice, Inbred BALB C; Neoplasms; Protein Kinase Inhibitors; Transcription, Genetic; Transforming Growth Factor alpha; Up-Regulation; Xenograft Model Antitumor Assays

Soluble isoforms of the epidermal growth factor receptor (sEGFR) previously have been identified in the conditioned culture media (CCM) of the vulvar adenocarcinoma cell line, A431 and within exosomes of the keratinocyte cell line HaCaT. Here, we report that the extracellular domain (ECD) of EGFR is shed from the cell surface of human carcinoma cell lines that express 7x10(5) receptors/cell or more. We purified this proteolytic isoform of EGFR (PI-sEGFR) from the CCM of MDA-MB-468 breast cancer cells. The amino acid sequence of PI-sEGFR was determined by reverse-phase HPLC nano-electrospray tandem mass spectrometry of peptides generated by trypsin, chymotrypsin or GluC digestion. The PI-sEGFR protein is identical in amino acid sequence to the EGFR ECD. The release of PI-sEGFR from MDA-MB-468 cells is enhanced by phorbol 12-myristate 13-acetate, heat-inactivated fetal bovine serum, pervanadate, and EGFR ligands (i.e., EGF and TGF-alpha). In addition, 4-aminophenylmercuric acetate, an activator of metalloproteases, increased PI-sEGFR levels in the CCM of MDA-MB-468 cells. Inhibitors of metalloproteases decreased the constitutive shedding of EGFR while the PMA-induced shedding was inhibited by metalloprotease inhibitors, by the two serine protease inhibitors leupeptin and 3,4-dichloroisocoumarin (DCI), and by the aspartyl inhibitor pepstatin. These results suggest that PI-sEGFR arises by proteolytic cleavage of EGFR via a mechanism that is regulated by both PKC- and phosphorylation-dependent pathways. Our results further suggest that when proteolytic shedding of EGFR does occur, it is correlated with a highly malignant phenotype.

Topics: Amino Acid Sequence; Animals; Cattle; Cell Line, Tumor; Enzyme Activation; Epidermal Growth Factor; ErbB Receptors; Humans; Molecular Sequence Data; Neoplasms; Peptides; Phenylmercuric Acetate; Protease Inhibitors; Protein Isoforms; Protein Kinase C; Protein Structure, Tertiary; Sequence Alignment; Spectrometry, Mass, Electrospray Ionization; Tetradecanoylphorbol Acetate; Transforming Growth Factor alpha; Vanadates

The latent membrane protein 1 (LMP1) of Epstein-Barr virus (EBV) is an oncoprotein expressed in several EBV-associated malignancies. We have utilised mice expressing the Cao strain of LMP1 in epithelia to explore the consequences of expression in vivo, specifically the changes that occur prior to neoplasia, in the hyperplastic but degenerating tissue. Epidermal growth factor receptor (EGFR) ligands (transforming growth factor alpha (TGFalpha), heparin-binding EGF-like growth factor and epiregulin) are constitutively induced by LMP1, leading to EGFR phosphorylation but also down-regulation, degradation or turn-over, with the appearance of cleaved EGFR fragments. This is accompanied by down-regulation of Akt and activation of caspase-3 and p38 mitogen-activated protein kinase (MAPK). Surprisingly, removal of TGFalpha (using the null strain) does not ameliorate the LMP1-induced phenotype, but instead accelerates the deterioration. Consistent with this, EGFR is reduced less rapidly and MAPK/ERK kinase (MEK) and extracellular-signal-regulated kinase (ERK) are initially activated in the null background, suggesting that TGFalpha or excess of the ligands together act to divert phosphorylated EGFR into a cleavage pathway. In addition, LMP1 leads to the activation of c-Jun N-terminal kinase 2 (JNK2) followed by JNK1 in the effected tissue. Specific AP1 family members FosB, Fra-1 and JunB are constitutively induced and serum response factor, AP1 and nuclear factor kappaB (incorporating p65) are activated in the transgenic tissue compared with wild-type. This system allows the analysis of early events resulting from the expression of a viral oncogene with broad impact in the signalling milieu and the attempts at homeostasis in the responding tissue. It reveals what regulatory circuits are in place in a normal tissue, thus facilitating further prediction of causative events in carcinogenic progression.

Topics: Animals; Down-Regulation; Enzyme Activation; ErbB Receptors; Extracellular Signal-Regulated MAP Kinases; Herpesvirus 4, Human; Humans; Mice; Mice, Knockout; Mice, Transgenic; Neoplasms; Proto-Oncogene Proteins c-akt; Transforming Growth Factor alpha; Viral Matrix Proteins

This symposium was held in Trento, Italy, from June 27 to 29, 2006, and was co-chaired by Robert Weinberg and Enrico Mihich. The interactions between tumor cells and their microenvironment were discussed with particular emphasis on their molecular mechanisms. The roles of transforming growth factor beta signaling, urokinase, and matrix metalloproteinases in matrix remodeling; the effects of matrix-tumor interactions on cell proliferation and migration; the tumor-promoting effects of inflammation and of related host cell and cytokine functions; the signaling mechanisms affecting the biology of the stroma; and the mechanisms governing angiogenesis were discussed.

Topics: Cell Division; Cell Movement; Humans; Inflammation; Matrix Metalloproteinases; Neoplasm Metastasis; Neoplasms; Placenta Growth Factor; Pregnancy Proteins; Research; Transforming Growth Factor alpha

Topics: Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Autocrine Communication; Cetuximab; Epidermal Growth Factor; ErbB Receptors; Erlotinib Hydrochloride; Exanthema; Humans; Ligands; Models, Biological; Neoplasm Proteins; Neoplasms; Paracrine Communication; Quinazolines; Skin; Transforming Growth Factor alpha; Treatment Outcome

Evidence suggests that CRIPTO-1 (CR-1) might be involved in the pathogenesis of human carcinoma. In the present study, we have screened the expression of CR-1 mRNA and protein in a wide panel of human cancer cell lines by using reverse transcriptase (RT)-PCR, real-time PCR and immunocytochemistry. Results of these experiments demonstrate that CR-1 is expressed in several, different carcinoma types. The anchorage-independent growth of colon, ovarian, lung and breast carcinoma cells was significantly inhibited by treatment with anti-CR-1 second generation antisense oligonucleotides. Similar results were obtained with anti-transforming growth factor alpha (TGF-alpha) and anti-amphiregulin (AR) antisense oligonucleotides. Treatment of carcinoma cells with CR-1 antisense oligonucleotides resulted in a significant reduction in the levels of expression of CR-1 mRNA and protein, and in the levels of activation of Akt. Finally, oral administration of either CR-1, AR or TGF-alpha antisense oligonucleotides produced a significant reduction in the growth of GEO colon carcinoma xenografts in nude mice that was associated with a reduction in the levels of expression of the target proteins. Taken together, these data strongly suggest that CR-1 might represent a novel target for therapeutic intervention in different carcinoma types.

Topics: Amphiregulin; Animals; Cell Line, Tumor; EGF Family of Proteins; Epidermal Growth Factor; Glycoproteins; GPI-Linked Proteins; Humans; Intercellular Signaling Peptides and Proteins; Membrane Glycoproteins; Mice; Neoplasm Proteins; Neoplasms; Oligonucleotides, Antisense; RNA, Messenger; Transforming Growth Factor alpha

The Raf serine-threonine kinase is upregulated in many human tumors and plays a pivotal role in tumor cell proliferation and survival. Abrogation of c-Raf expression by specific antisense oligonucleotides (Raf-AS-ODN) efficiently blocks tumor cell growth and induces apoptosis in human cancer cells. The signaling pathways and molecular mechanisms c-Raf utilizes to mediate the survival of tumor cells are, however, not well understood. Here we show that apoptosis triggered by Raf depletion cannot be overcome by ectopic Bcl-2 expression and occurs in the absence of cytochrome c release, arguing against a direct impact of c-Raf on mitochondrial pathways of apoptosis regulation. We also show that c-Raf depletion leads to a clearly decreased expression of different epidermal growth factor (EGF) receptor ligands, suggesting that the autocrine stimulation of an EGF receptor-mediated survival pathway might be involved in the blockade of tumor cell apoptotis by c-Raf.

Topics: Apoptosis; Cytochrome c Group; ErbB Receptors; HeLa Cells; Humans; MAP Kinase Kinase 1; MAP Kinase Kinase 2; Mitogen-Activated Protein Kinase Kinases; Neoplasms; Oligonucleotides, Antisense; Protein Serine-Threonine Kinases; Protein-Tyrosine Kinases; Proto-Oncogene Proteins c-bcl-2; Proto-Oncogene Proteins c-raf; Transforming Growth Factor alpha

The factors and mechanisms that transduce the intracellular signals sent upon activation of the receptor for the epidermal growth factor (EGFR) and related receptors are reasonably well understood and, in fact, are the targets of anti-tumor drugs. In contrast, less is known about the mechanisms implicated in sending the signals that activate these receptors. Here we show that when its proteolytic shedding is prevented, the transmembrane form of the transforming growth factor-alpha (proTGF-alpha) interacts with, but does not activate, the EGFR. Thus, shedding seems to control not only the availability of the soluble form of the growth factor (TGF-alpha) but also the activity of the transmembrane form. The activity of the protease responsible for the shedding of proTGF-alpha, tumor necrosis factor-alpha converting enzyme (TACE), is required for the activation of the EGFR in vivo and for the development of tumors in nude mice, indicating a crucial role of TACE in tumorigenesis. In agreement with this view, TACE is dramatically overexpressed in the majority of mammary tumors analyzed. Collectively, this evidence points to TACE as a promising target of anti-tumor therapy.

Topics: ADAM Proteins; ADAM17 Protein; Amino Acid Sequence; Amyloid Precursor Protein Secretases; Animals; Aspartic Acid Endopeptidases; Breast Neoplasms; Carcinogenicity Tests; CHO Cells; Cricetinae; Culture Media, Conditioned; Endopeptidases; ErbB Receptors; Female; HeLa Cells; Humans; Matrix Metalloproteinases, Membrane-Associated; Metalloendopeptidases; Mice; Mice, Nude; Neoplasms; Transforming Growth Factor alpha; Transplantation, Heterologous

The aim of this review was to describe expression of epithelial growth factor receptor (EGFR) and of its ligands in a panel of tumours (which are not specified elsewhere in this special issue of Bulletin du Cancer): squamous cell carcinomas, adenocarcinomas, sarcomas, brain and germ line tumours. The role of EGFR and its ligands in the carcinogenesis and the progression of these tumours, as well as the relevance of targeting EGFR.

Topics: Adenocarcinoma; Carcinoma, Squamous Cell; ErbB Receptors; Female; Humans; Male; Neoplasm Proteins; Neoplasms; Sarcoma; Transforming Growth Factor alpha

Clinical responses to the HER1 (EGF receptor) inhibitors and HER2/neu/ErbB2 inhibitors correlate with high levels of receptor expression. However, a significant subset of patients with high receptor levels appear to be refractory to treatment. We have observed similar results in the 60 cell lines of the NCI Anti-Cancer Drug Screen using a panel of 11 selective HER1 inhibitors. As expected, low HER1-expressing cell lines were insensitive to HER1 inhibitors. In cell lines with high HER1 expression, low concentrations of HER1 inhibitors potently inhibit both HER1 phosphorylation and the mitogen-activated protein kinase (MAPK) pathway. However, this inhibition did not always correlate with cellular arrest. High HER1-expressing cell lines can be subdivided into two groups based on their sensitivity to HER1 inhibitors. In the sensitive group, receptor and growth inhibition was concordant and occurred at sub-micromolar concentrations of HER1 inhibitors. In the insensitive group, receptor inhibition occurred at a low concentration (< 1 microM) but concentrations that were ten times or higher were required for growth inhibition. Also, neither induction of p21 and cyclin D1 nor p53 status could explain the difference between sensitive and insensitive cells. Although EGF activated the MAPK pathway in all cell lines, only drug-sensitive cell lines responded to EGF (accelerated entry from G1 to S) and to HER1 inhibitors (G1 arrest) by changes in cell cycling. Furthermore, an EGF-dependent immortalized mammary epithelial cell line was extremely sensitive to a panel of HER1 inhibitors. We infer that independence from mitogen-mediated signaling confers insensitivity to HER1 inhibitors in a large subset of cancer cell lines.

Topics: Cell Cycle; Cell Line, Transformed; Cyclin D1; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; Drug Resistance, Neoplasm; Enzyme Induction; Enzyme Inhibitors; ErbB Receptors; Female; Gene Expression Regulation, Neoplastic; Humans; Male; MAP Kinase Signaling System; Neoplasm Proteins; Neoplasms; Pyrimidines; Quinazolines; Receptor, ErbB-2; Transforming Growth Factor alpha; Tumor Cells, Cultured; Tumor Suppressor Protein p53; Tyrphostins

We have previously described a rat monoclonal antibody, RS-11, which recognizes a tumor-associated antigen common to several species. In the present study, we have cloned and characterized the antigen recognized by RS-11. We screened a phage expression library prepared from HeLa cDNA and identified a clone that reacts with RS-11. DNA sequence analysis revealed that this clone contains sequences of keratin 18 (nucleotides 568-1196). We constructed several glutathione S-transferase fusion proteins and synthetic peptides based on this DNA sequence analysis and examined their reactivity with RS-11 to accurately map the RS-11 epitope. We determined that the epitope resides within a region of seven amino acids on the alpha-helix 2B domain of keratin 18 in which two amino acids (Leu(366) and Lys(370)) are completely conserved among intermediate filaments as well as other keratin members that are immunoreactive with RS-11. These two residues are sequentially discontinuous but spatially adjacent. The RS-11 epitope is constitutively present in human primary cultured hepatocytes; however, its immunoreactivity with RS-11 is up-regulated by malignant transformation or stimulation with either epidermal growth factor or transforming growth factor alpha.

Topics: Amino Acid Sequence; Animals; Antibodies, Monoclonal; Base Sequence; Blotting, Western; Cells, Cultured; DNA Primers; Epidermal Growth Factor; Epitope Mapping; Epitopes; HeLa Cells; Humans; Liver; Molecular Sequence Data; Neoplasms; Rats; RNA, Messenger; Transforming Growth Factor alpha; Tumor Cells, Cultured

The pathogenesis of cancer-associated hypercalcemia is not yet completely understood. This syndrome appears to be a consequence of the tumor production of humoral factors, mainly parathyroid hormone related protein (PTHrP). However, patients with humoral hypercalcemia of malignancy have features suggesting that factors other than PTHrP might play a role in this syndrome. We performed a case-control study in cancer patients with and without hypercalcemia. A total of 105 patients with a variety of tumors, 60 of them with hypercalcemia (corrected serum calcium over 2.6 mmol/l), and 45 without hypercalcemia. In a previous study, we demonstrated that plasma PTHrP was highly associated with hypercalcemia in these patients. In the present study, we measured the plasma levels of various bone cytokines: interleukin-1beta (IL-1beta), interleukin-6 (IL-6), transforming growth factor (TGF) alpha, and tumor necrosis factor (TNF) alpha, in these cancer patients. We also determined C-terminal type I procollagen (PICP) and C-terminal telopeptide of type I collagen (ICTP), bone formation and bone resorption markers, respectively, in serum in these patients. We found that these osteolytic cytokines do not increase in plasma by the presence of hypercalcemia. In fact, using a logistic regression analysis, a significant (P<0.02) association was found between the low plasma levels of IL-1beta and TGFalpha and hypercalcemia, independent of plasma PTHrP and the presence of bone metastasis, in these patients. No significant association between the plasma levels of IL-6 or TNFalpha and hypercalcemia was found in these cancer patients. Serum ICTP correlated (r=0.35; P=0.008) with hypercalcemia in these patients, but none of the cytokines studied in plasma correlated with either ICTP or PICP in these hypercalcemic patients. Our data indicate that the circulating levels of several bone cytokines are not enhanced by PTHrP in hypercalcemic cancer patients. The mechanism responsible for the association between the low plasma levels of some of these cytokines and hypercalcemia in these patients remains obscure. However, this finding does not rule out the possible local bone effects of these cytokines, contributing to hypercalcemia in cancer patients.

Topics: Adult; Aged; Aged, 80 and over; Biomarkers; Bone and Bones; Bone Development; Bone Resorption; Collagen; Collagen Type I; Cytokines; Humans; Hypercalcemia; Interleukin-1; Interleukin-6; Middle Aged; Neoplasms; Parathyroid Hormone-Related Protein; Peptide Fragments; Peptides; Procollagen; Proteins; Transforming Growth Factor alpha; Tumor Necrosis Factor-alpha

The human transforming growth factor-alpha (TGF-alpha) gene is thought to contain five introns and six exons, encoding a transmembrane precursor (proTGF-alpha) from which the mature polypeptide is released by proteolytic cleavage. We identified a novel 32-nucleotide exon (exon alpha) within intron 5 and an alternative splice acceptor site in exon 6, splitting exon 6 into two segments: 6A and 6B. Therefore, in addition to wild type (wt) proTGF-alpha mRNA, which skips exon alpha, two novel proTGF-alpha variants are produced: Variant I (VaI), skipping exons alpha and 6A, and Variant II (VaII) which includes exon alpha and skips exon 6A. The only significant difference between variant and wt proTGF-alpha proteins is that the two wt carboxyl-terminal valines are replaced in the variants by five or four other amino acids, respectively. Both variant TGF-alpha mRNAs were readily detected in human keratinocytes and tumor-derived cell lines. Their protein products were cleaved as efficiently as wt TGF-alpha in response to the calcium ionophore A23187. However, both variants (but not wt) reduced serum requirements for proliferation in CHO cells. In addition, VaII-expressing CHO cells (not VaI or wt) formed foci in monolayer cultures. These results suggest that variant TGF-alpha precursors induce autonomous growth.

Topics: Amino Acid Substitution; Animals; Calcimycin; Calcium; CHO Cells; Cricetinae; Cricetulus; Exons; Humans; Introns; Ionophores; Keratinocytes; Molecular Sequence Data; Neoplasms; Protein Processing, Post-Translational; Recombinant Fusion Proteins; RNA Splicing; RNA, Messenger; RNA, Neoplasm; Serine Endopeptidases; Transforming Growth Factor alpha; Tumor Cells, Cultured; Valine

Topics: Biomarkers, Tumor; ErbB Receptors; Female; Gene Expression Regulation, Neoplastic; Head and Neck Neoplasms; Humans; Male; Neoplasm Proteins; Neoplasms; Prognosis; Risk; Transforming Growth Factor alpha

Topics: Epidermal Growth Factor; Fibroblast Growth Factor 2; Growth Substances; Humans; Neoplasms; Neovascularization, Pathologic; Transforming Growth Factor alpha

Gliomas, squamous carcinomas and different adenocarcinomas from breast, colon and prostate might have an increased number of epidermal growth factor (EGF) receptors. The receptors are, in these cases, candidates for binding of receptor specific toxic conjugates that might inactivate cellular proliferation. The purpose of this study was to evaluate whether it is reasonable to try ligand-dextran based conjugates for therapy.. EGF or TGF alpha were conjugated to dextran and binding, internalization, retention and degradation of eight types of such conjugates were analyzed in EGF-receptor amplified glioma cells. The conjugates were labelled with radioactive nuclides to allow detection and two of the conjugates were carrying boron in the form of carboranyl amino acids or aminoalkyl-carboranes. Comparative binding tests, applying 125I-EGF, were made with cultured breast, colon and prostate adenocarcinoma, glioma and squamous carcinoma cells. Some introductory tests to label with 76Br for positron emission tomography and with 131I for radionuclide therapy were also made.. The dextran part of the conjugates did not prevent receptor specific binding. The amount of receptor specific binding varied between the different types of conjugates and between the tested cell types. The dextran part improved intracellular retention and radioactive nuclides were retained for at least 20-24 h. The therapeutical effect improved when 131I was attached to EGF-dextran instead of native EGF.. The improved cellular retention of the ligand-dextran conjugates is an important property since it gives extended exposure time when radionuclides are applied and flexibility in the choice of time for application of neutrons in boron neutron capture therapy (BNCT). It is possible that ligand-dextran mediated BNCT might allow, if the applied neutron fields covers rather wide areas around the primary tumor, locally spread cells that otherwise would escape treatment to be inactivated.

Topics: Adenocarcinoma; Animals; Boron Compounds; Boron Neutron Capture Therapy; Carcinoma; Colonic Neoplasms; Dextrans; Drug Carriers; Epidermal Growth Factor; ErbB Receptors; Glioma; Humans; Iodine Radioisotopes; Male; Mammary Neoplasms, Experimental; Models, Biological; Neoplasms; Neoplasms, Experimental; Prostatic Neoplasms; Rats; Rats, Sprague-Dawley; Transforming Growth Factor alpha; Tumor Cells, Cultured

The stroma reaction has an important role in tumor growth, invasion, and metastasis. In various invasive human carcinomas, as well as in a mouse model for tumor invasion, transcripts encoding the transcription factor c-Ets1 were detected within stromal fibroblasts, whereas they were absent in epithelial tumor cells. This expression of c-Ets1 was often increased in fibroblasts directly adjacent to neoplastic cells. Endothelial cells of stromal capillaries were also positive for c-Ets1 expression. In contrast, fibroblasts of corresponding noninvasive lesions and of normal tissues were consistently negative. In cultured human fibroblasts stimulated by basic fibroblast growth factor and tumor necrosis factor alpha, the expression of c-Ets1 correlated with the accumulation of transcripts for potential target genes, collagenase-1 and stromelysin-1. The same correlation was observed in some of the invasive carcinomas investigated. These results suggest that c-Ets1 participates in the regulation of tumor invasion in vivo.

Topics: Adult; Aged; Animals; Collagenases; Female; Fibroblast Growth Factor 2; Fibroblasts; Humans; In Situ Hybridization; Male; Matrix Metalloproteinase 3; Metalloendopeptidases; Mice; Mice, SCID; Middle Aged; Neoplasm Invasiveness; Neoplasms; Oncogene Proteins; Platelet-Derived Growth Factor; Proto-Oncogene Proteins c-ets; RNA, Messenger; Transcription Factors; Transcription, Genetic; Transforming Growth Factor alpha; Transforming Growth Factor beta; Urokinase-Type Plasminogen Activator

Humoral hypercalcemia of malignancy is a multifactorial syndrome caused by the action of tumor-produced factors on target organs of bone, kidney, and intestine to disrupt normal calcium homeostasis. Although parathyroid hormone-related protein (PTHrP) plays an integral role in the syndrome, tumors also produce other hypercalcemic factors, such as transforming growth factor-alpha (TGF-alpha), which may modulate the effects of PTHrP. In order to determine if the effects of PTHrP on calcium homeostasis can be modulated by TGF-alpha, we have used a human squamous cell carcinoma cell line (RWGT2) which produces PTHrP alone and Chinese hamster ovarian (CHO) cells expressing only transfected human TGF-alpha complementary DNA (CHO/TGF-alpha). We studied the effects of these tumors on calcium homeostasis in nude mice bearing both tumors or each tumor alone. Whole blood ionized calcium concentrations (mean +/- SEM in mmol/L) were significantly higher in mice bearing both RWGT2 and CHO/TGF-alpha tumors (3.11 +/- 0.06, P < 0.05) when compared with mice bearing either RWGT2 alone (2.02 +/- 0.06), CHO/TGF-alpha alone (1.42 +/- 0.01), or RWGT2 and nontransfected CHO tumors (1.86 +/- 0.01). This enhanced effect was also observed using continuous PTHrP-(1-34) infusion (2 micrograms/day) in mice bearing CHO/TGF-alpha tumors. In addition, tumor cell conditioned media was tested for bone resorbing activity in organ cultures of fetal rat long bones previously incorporated with 45calcium (45Ca++). Conditioned medium at 0.1% (vol/vol) from either RWGT2 or CHO/TGF-alpha had no bone resorbing activity over control (%45Ca++ release, mean +/- SEM; control 23 +/- 1, RWGT2 19 +/- 1, CHO/TGF-alpha 23 +/- 1). However, the combination of 0.1% conditioned medium from RWGT2 and CHO/TGF-alpha significantly increased bone resorption (53 +/- 2, P < 0.05). These data demonstrate that the hypercalcemic effects of tumor-produced PTHrP are enhanced by TGF-alpha and that this effect may be due to increased bone resorption.

Topics: Animals; Bone and Bones; Bone Resorption; Carcinoma, Squamous Cell; CHO Cells; Cricetinae; Culture Media, Conditioned; Humans; Hypercalcemia; Lung Neoplasms; Male; Mice; Mice, Inbred BALB C; Mice, Nude; Middle Aged; Neoplasms; Parathyroid Hormone-Related Protein; Protein Biosynthesis; Proteins; Rats; Recombinant Proteins; Transfection; Transforming Growth Factor alpha; Tumor Cells, Cultured

Topics: Animals; Cell Division; Neoplasms; Receptors, Cell Surface; Receptors, Transforming Growth Factor beta; Signal Transduction; Transforming Growth Factor alpha; Transforming Growth Factor beta

Topics: Angiogenesis Inducing Agents; Animals; Neoplasms; Oncogenes; RNA, Messenger; Transforming Growth Factor alpha

Topics: Growth Substances; Humans; Neoplasms; Transforming Growth Factor alpha; Transforming Growth Factor beta; Transforming Growth Factors

Topics: Amino Acid Sequence; Animals; Cell Transformation, Neoplastic; Fibroblast Growth Factors; Humans; Molecular Sequence Data; Neoplasms; Platelet-Derived Growth Factor; Transforming Growth Factor alpha; Transforming Growth Factor beta

Transforming growth factor alpha (TGF alpha)-Pseudomonas exotoxin 40 (PE40) is a chimeric protein consisting of an N-terminal TGF alpha domain fused to a C-terminal 40-kDa segment of the Pseudomonas exotoxin A protein. TGF alpha-PE40 exhibits the receptor-binding activity of TGF alpha and the cell-killing activity of PE40. These properties make TGF alpha-PE40 an effective cytotoxic agent for cells that possess epidermal growth factor receptors (EGFR). However, the utility of this protein as an anticancer agent has been unclear because many normal tissues express EGFR and may be damaged by exposure to TGF alpha-PE40. To address this issue, we injected nude mice with a lethal inoculum of either A431 or HT29 human tumor cells that possess EGFR or with Chinese hamster ovary (CHO) tumor cells that lack EGFR. Animals were treated with a derivative of TGF alpha-PE40 in which the cysteine residues are replaced by alanine, termed "TGF alpha-PE40 delta cys," or with saline once a day for 5 days. Mice bearing EGFR+ tumor cells lived significantly (P less than 0.001) longer when treated with TGF alpha-PE40 delta cys compared with saline-treated controls (median survival: A431 cells, 51.5 vs. 25.5 days; HT29 cells, 101 vs. 47.5 days). TGF alpha-PE40 delta cys did not prolong the survival of mice bearing tumor cells that lack EGFR (median survival: CHO cells, 15.5 vs. 19.5 days). The only toxicity to normal tissues was mild periportal hepatic necrosis. These studies indicate that a therapeutic window exists in vivo for the use of some growth factor-toxin fusion proteins as anticancer agents.

Topics: ADP Ribose Transferases; Alanine; Animals; Antineoplastic Agents; Bacterial Toxins; Cell Line; Cloning, Molecular; Cysteine; ErbB Receptors; Exotoxins; Female; Humans; Mice; Mice, Nude; Mutation; Neoplasm Transplantation; Neoplasms; Pseudomonas aeruginosa Exotoxin A; Recombinant Fusion Proteins; Transforming Growth Factor alpha; Transforming Growth Factors; Virulence Factors