transforming-growth-factor-alpha and Kidney-Neoplasms

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

Clear-cell renal cell carcinoma (RCC) is characterized by the loss of von Hippel-Lindau disease protein and the resultant dysregulation of the vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR), platelet-derived growth factor-beta (PDGF-beta)/PDGF receptor-beta (PDGFR-beta), and transforming growth factor-alpha (TGF-alpha)/epidermal growth factor receptor (EGFR)/Raf pathways, which contribute to angiogenesis, lymphangiogenesis, and tumor cell growth and survival. Significant advances in the treatment of clear-cell RCC have been derived from agents that target these pathways, including the multiple-kinase inhibitors (MKIs) sorafenib, sunitinib, and AG013736, which target multiple VEGFRs as well as PDGFR-beta. Sorafenib has the added advantage of inhibiting multiple different Raf isoforms, which enables it to target TGF-alpha/EGFR signaling and may also enhance its inhibition of VEGFR and PDGFR-beta. This review will examine the recent advances in our understanding of the biology of clear-cell RCC and show how those advances have helped delineate new targets of opportunity for treatment. It will also present the early clinical results of agents that target the pathways dysregulated in clear-cell RCC, with special emphasis on sorafenib and the other active MKIs, and will describe the scientific rationales for ongoing and future sorafenib-based combination therapy trials in RCC.

Topics: Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Benzenesulfonates; Carcinoma, Renal Cell; ErbB Receptors; Humans; Kidney Neoplasms; Niacinamide; Phenylurea Compounds; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-sis; Pyridines; Signal Transduction; Sorafenib; Transforming Growth Factor alpha; Vascular Endothelial Growth Factor A; Von Hippel-Lindau Tumor Suppressor Protein

Recent studies on the mechanisms of normal epithelial development in the kidney, and on the aetiology of renal neoplasms, are converging to reveal remarkably close relationships between the phenotypes and behaviours of normally-developing and neoplastic cells. Normal renal epithelia arise from two sources; those of the collecting duct system develop by arborisation of an initially-unbranched ureteric bud, in a manner similar to the development of other glandular organs, while epithelial nephrons develop via an unusual mesenchyme-to-epithelial transition. Both types of development require controlled proliferation, cell-cell and cell-matrix interactions, protease activity etc., but of the two tissues, the development of the nephrons is arguably the more complex. It includes many defined stages, signals and checkpoints that ensure that events happen at the right time, and that processes such as proliferation, apoptosis and differentiation are properly balanced. Detailed investigation of renal neoplasms has revealed some to be caused by mutations in molecules with known roles in normal nephrogenesis (e.g. Wilms' tumour and the WT-1 gene, renal cell carcinoma and the c-met receptor tyrosine kinase gene), some to be caused by mutations in genes expressed during normal development (e.g. renal cell carcinoma and the TSC-2 gene, renal cell carcinoma of the clear cell variety and the VHL gene). Furthermore, these and other tumours of unknown aetiology re-express genes such as Pax-2 that are expressed during the normal mesenchyme-to-epithelium transition but are shut off during terminal differentiation. Their re-appearance in tumours suggests that the cells have 'regressed' in an ontogenic sense, and their biology may therefore be understood most clearly by reference to the properties of normal developing cells rather than cells of a mature kidney.

Topics: Animals; Carcinoma, Renal Cell; DNA-Binding Proteins; Genes, Tumor Suppressor; Humans; Kidney; Kidney Neoplasms; Nephrons; Nuclear Proteins; Paired Box Transcription Factors; PAX2 Transcription Factor; PAX8 Transcription Factor; Repressor Proteins; Trans-Activators; Transcription Factors; Transforming Growth Factor alpha; Tuberous Sclerosis Complex 2 Protein; Tumor Suppressor Proteins; Urothelium; von Hippel-Lindau Disease; Wilms Tumor

In man, RCC makes up the largest proportion of primary kidney cancers, comprising approximately 85% of renal tumors and accounting for approximately 2% of the cancer deaths each year (Richie and Skinner 1981). As shown in Table 2, there are many similarities between spontaneous rat RCC and human RCC. Therefore, rat RCC and the Eker rat model in particular appear to be well suited to investigations into the mechanisms by which this disease occurs. In addition, animal models such as the Eker rat may also be valuable as human surrogates for developing and testing new approaches for treatment of human renal cancer.

Topics: Animals; Carcinoma, Renal Cell; Disease Models, Animal; Gene Expression Regulation, Neoplastic; Genes, ras; Humans; Karyotyping; Kidney Neoplasms; Rats; Transforming Growth Factor alpha

The purpose of our study was to explore the effect and intrinsic mechanism of wild-type IDH1 and its substrate α-KG on renal cell carcinoma (RCC). IDH1 was observed lower expression in RCC cell lines. Phenotype experiment was carried out in the wild-type IDH1 and mutant IDH1

Topics: Animals; Apoptosis; Carcinoma, Renal Cell; Cell Line, Tumor; Cell Movement; Drug Discovery; Gene Expression Regulation, Neoplastic; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Isocitrate Dehydrogenase; Kidney Neoplasms; Mice; Transforming Growth Factor alpha; Vascular Endothelial Growth Factor A; Von Hippel-Lindau Tumor Suppressor Protein; Xenograft Model Antitumor Assays

This study reevaluates the potential role of different tumour markers as prognostic indicators in untreated nephroblastoma.. Expression of a broad panel of tumour markers was investigated by means of immunohistochemical analysis in 43 WT patients. Patients were treated by radical nephrectomy and had a mean follow-up of 11.9 years.. Generally, all the tumour markers studied were expressed in normal kidney tissue and at variable levels in the three cell types of WT (blastema, epithelium and stroma). Immunoreactive blastemal (Bcl-X, Bcl-2 and CD44s) and epithelial (Bcl-X, Bcl-2 and MIB-1) cells were present in the majority of tumours. No correlation was found between their expression and pathological stages. Univariate analysis showed that blastemal WT-1, TGF-α, VEGF, MIB-1 and p27 Kip1 were indicative for clinical progression. In a multivariate analysis, WT-1 protein expression by blastemal cells was an independent prognostic marker for clinical progression.. The blastemal WT-1, TGF-α, VEGF, MIB-1 and p27Kip1 expression correlate with clinical progression in untreated nephroblastoma. Therefore, their expression may be of value in identifying patients with a high propensity to develop distant metastases.

Topics: Adolescent; Biomarkers, Tumor; Cyclin-Dependent Kinase Inhibitor p27; Disease Progression; Female; Follow-Up Studies; Humans; Immunohistochemistry; Kidney Neoplasms; Male; Nephrectomy; Predictive Value of Tests; Prognosis; Transforming Growth Factor alpha; Treatment Outcome; Ubiquitin-Protein Ligases; Vascular Endothelial Growth Factor A; Wilms Tumor; WT1 Proteins

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

Patients with renal cell carcinomas (RCC) have few treatment options, underscoring the importance of developing new approaches such as immunotherapy. However, few tumor associated antigens (TAA), which can be targeted by immunotherapy, have been identified for this type of cancer. von Hippel-Lindau clear cell RCC (VHL(-/-)RCC) are characterized by mutations in the VHL tumor suppressor gene. Loss of VHL function causes the overexpression of transforming growth factor (TGF)-alpha, leading us to hypothesize that TGF-alpha could be a potential TAA for immunotherapy of kidney cancer, which was evaluated in this study.. We first confirmed the absent or weak expression of TGF-alpha in important normal tissues as well as its overexpression in 61% of renal tumors in comparison to autologous normal kidney tissues. In addition, we demonstrated the immunogenicity of TGF-alpha, by expanding many T cell lines specific for certain TGF-alpha peptides or the mature TGF-alpha protein, when presented by major histocompatibility complex (MHC) molecules on the surface of antigen-presenting cells. Interestingly, some of these TGF-alpha-specific T cells were polyfunctionals and secreted IFN-gamma, TNF-alpha and IL-2.. We have shown that TGF-alpha is a valid candidate TAA, which should allow the development of a targeted immunotherapy.

Topics: Antigens, Neoplasm; Carcinoma, Renal Cell; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Cell Line; Cell Line, Tumor; Humans; Kidney Neoplasms; Lymphocytes, Tumor-Infiltrating; Peptides; Transforming Growth Factor alpha; Von Hippel-Lindau Tumor Suppressor Protein

Malignancy is a manifestation of acquired defects in regulatory circuits that direct normal cell proliferation and homeostasis. Most of these circuits operate through cell autonomous pathways, whereas others potentially involve the neighboring microenvironment. We report that the metalloprotease ADAM17 plays a pivotal role in several acquired tumor cell capabilities by mediating the availability of soluble transforming growth factor-alpha, an epidermal growth factor receptor (EGFR) ligand, and thus the establishment of a key autocrine signaling pathway. Silencing of ADAM17 in human renal carcinoma cell lines corrects critical features associated with cancer cells, including growth autonomy, tumor inflammation, and tissue invasion. Highly malignant renal carcinoma cancer cells fail to form in vivo tumors in the absence of ADAM17, confirming the essential function of this molecule in tumorigenesis. These data show that ligand shedding is a crucial step in endogenous EGFR activation and endorse prospective therapeutic strategies targeting ADAM17 in human cancer.

Topics: ADAM Proteins; ADAM17 Protein; Carcinoma, Renal Cell; Cell Division; Cell Line, Tumor; Gene Silencing; Humans; Kidney Neoplasms; Reverse Transcriptase Polymerase Chain Reaction; RNA, Neoplasm; Transforming Growth Factor alpha; von Hippel-Lindau Disease

Inactivating mutations in the von Hippel-Lindau (VHL) tumor suppressor gene are associated with clear cell renal cell carcinoma (VHL-/- RCC), the most frequent malignancy of the human kidney. The VHL protein targets the alpha subunits of hypoxia-inducible factor (HIF) transcription factor for ubiquitination and degradation. VHL-/- RCC cells fail to degrade HIF resulting in the constitutive activation of its target genes, a process that is required for tumorigenesis. We recently reported that HIF activates the transforming growth factor-alpha/epidermal growth factor receptor (TGF-alpha/EGFR) pathway in VHL-defective RCC cells. Here, we show that short hairpin RNA (shRNA)-mediated inhibition of EGFR is sufficient to abolish HIF-dependent tumorigenesis in multiple VHL-/- RCC cell lines. The 2alpha form of HIF (HIF-2alpha), but not HIF-1alpha, drives in vitro and in vivo tumorigenesis of VHL-/- RCC cells by specifically activating the TGF-alpha/EGFR pathway. Transient incubation of VHL-/- RCC cell lines with small interfering RNA directed against EGFR prevents autonomous growth in two-dimensional culture as well as the ability of these cells to form dense spheroids in a three-dimensional in vitro tumor assay. Stable expression of shRNA against EGFR does not alter characteristics associated with VHL loss including constitutive production of HIF targets and defects in fibronectin deposition. In spite of this, silencing of EGFR efficiently abolishes in vivo tumor growth of VHL loss RCC cells. These data identify EGFR as a critical determinant of HIF-2alpha-dependent tumorigenesis and show at the molecular level that EGFR remains a credible target for therapeutic strategies against VHL-/- renal carcinoma.

Topics: Basic Helix-Loop-Helix Transcription Factors; Carcinoma, Renal Cell; Cell Growth Processes; Cell Line, Tumor; ErbB Receptors; Gene Expression Regulation, Neoplastic; Gene Silencing; Humans; Kidney Neoplasms; RNA, Small Interfering; Transcription Factors; Transforming Growth Factor alpha; Tumor Suppressor Proteins; Ubiquitin-Protein Ligases; Von Hippel-Lindau Tumor Suppressor Protein

Defective function of the von Hippel-Lindau (VHL) tumor suppressor ablates proteolytic regulation of hypoxia-inducible factor alpha subunits (HIF-1alpha and HIF-2alpha), leading to constitutive activation of hypoxia pathways in renal cell carcinoma (RCC). Here we report a comparative analysis of the functions of HIF-1alpha and HIF-2alpha in RCC and non-RCC cells. We demonstrate common patterns of HIF-alpha isoform transcriptional selectivity in VHL-defective RCC that show consistent and striking differences from patterns in other cell types. We also show that HIF-alpha isoforms display unexpected suppressive interactions in RCC cells, with enhanced expression of HIF-2alpha suppressing HIF-1alpha and vice-versa. In VHL-defective RCC cells, we demonstrate that the protumorigenic genes encoding cyclin D1, transforming growth factor alpha, and vascular endothelial growth factor respond specifically to HIF-2alpha and that the proapoptotic gene encoding BNip3 responds positively to HIF-1alpha and negatively to HIF-2alpha, indicating that HIF-1alpha and HIF-2alpha have contrasting properties in the biology of RCC. In keeping with this, HIF-alpha isoform-specific transcriptional selectivity was matched by differential effects on the growth of RCC as tumor xenografts, with HIF-1alpha retarding and HIF-2alpha enhancing tumor growth. These findings indicate that therapeutic approaches to targeting of the HIF system, at least in this setting, will need to take account of HIF isoform-specific functions.

Topics: Amino Acid Sequence; Animals; Basic Helix-Loop-Helix Transcription Factors; Carcinoma, Renal Cell; Cell Line, Tumor; Cyclin D; Cyclins; DNA-Binding Proteins; Genes, Tumor Suppressor; Humans; Hypoxia-Inducible Factor 1; Hypoxia-Inducible Factor 1, alpha Subunit; Immunohistochemistry; Kidney Neoplasms; Mice; Mice, Nude; Mutation; Neoplasm Transplantation; Nuclear Proteins; Protein Structure, Tertiary; Retroviridae; RNA, Small Interfering; Transcription Factors; Transforming Growth Factor alpha; Transplantation, Heterologous; Vascular Endothelial Growth Factor A; von Hippel-Lindau Disease

Inactivation of the von Hippel-Lindau tumor suppressor (VHL) is an early event in >60% of sporadic clear cell renal cell carcinoma (RCC). Loss of VHL E3 ubiquitin ligase function results in accumulation of the alpha-subunit of the hypoxia-inducible heterodimeric transcription factor (HIF-alpha) and transcription of an array of genes including vascular endothelial growth factor, transforming growth factor-alpha, and erythropoietin. Studies have shown that HIF-alpha can be alternatively activated by reactive oxygen species. Nox4 is an NADP(H) oxidase that generates signaling levels of superoxide and is found in greatest abundance in the distal renal tubules. To determine if Nox4 contributes to HIF activity in RCC, we examined the impact of Nox4 expression on HIF-alpha expression and transactivation. We report here that small inhibitory RNA (siRNA) knockdown of Nox4 in 786-0 human renal tumor cells expressing empty vector (PRC) or wild-type VHL (WT) results in 50% decrease in intracellular reactive oxygen species as measured by a fluorescent 2',7'-dichlorofluorescin diacetate assay, and >85% reduction in HIF2-alpha mRNA and protein levels by quantitative reverse transcription-PCR and Western blot analysis. Furthermore, expression of the HIF target genes, vascular endothelial growth factor, transforming growth factor-alpha, and Glut-1 was abrogated by 93%, 74%, and 99%, respectively, after stable transfection with Nox4 siRNA relative to nontargeting siRNA, as determined by quantitative reverse transcription-PCR. Thus, renal Nox4 expression is essential for full HIF2-alpha expression and activity in 786-0 renal tumor cells, even in the absence of functional VHL. We propose the use of Nox4 as a target in the treatment of clear cell RCC.

Topics: Amino Acid Sequence; Basic Helix-Loop-Helix Transcription Factors; Carcinoma, Renal Cell; Gene Expression Regulation, Neoplastic; HeLa Cells; Humans; Kidney Neoplasms; Molecular Sequence Data; NADPH Oxidase 4; NADPH Oxidases; Reactive Oxygen Species; RNA, Small Interfering; Transcriptional Activation; Transfection; Transforming Growth Factor alpha; Vascular Endothelial Growth Factor A; Von Hippel-Lindau Tumor Suppressor Protein

Renal cell carcinoma (RCC) frequently produces metastases to the musculoskeletal system that are a major source of morbidity in the form of pain, immobilization, fractures, neurological compromise, and a decreased ability to perform activities of daily living. Patients with metastatic RCC therefore have a dismal prognosis because there is no effective adjuvant treatment for this disease. Because the epidermal growth factor receptor (EGF-R) signaling cascade is important in the growth and metastasis of RCC, its blockade has been hypothesized to inhibit tumor growth and hence prevent resultant bone destruction. We determined whether blockade of EGF-R by the tyrosine kinase inhibitor PKI 166 inhibited the growth of RCC in bone. We use a novel cell line, RBM1-IT4, established from a human RCC bone metastasis. Protein and mRNA expression of the ligands and receptors was assessed by Western and Northern blots. The stimulation of RBM1-IT4 cells with epidermal growth factor or transforming growth factor alpha resulted in increased cellular proliferation and tyrosine kinase autophosphorylation. PKI 166 prevented these effects. First, RBM1-IT4 cells were implanted into the tibia of nude mice, where they established lytic, progressively growing lesions, after which the mice were treated with PKI 166 alone or in combination with paclitaxel (Taxol). Immunohistochemical analysis revealed that tumor cells and tumor-associated endothelial cells in control mice expressed activated EGF-R. Treatment of mice with PKI 166 alone or in combination with Taxol produced a significant decrease in the incidence and size of bone lesions as compared with the results in control or Taxol-treated mice (P < 0.001). Treatment with PKI 166 also decreased the expression of phosphorylated EGF-R by tumor cells and tumor-associated endothelial cells, and this was even more pronounced with PKI 166 plus Taxol treatment. The PKI 166 plus Taxol combination produced apoptosis of tumor cells and tumor-associated endothelial cells. Tumor cell proliferation, shown by proliferating cell nuclear antigen positivity, was decreased in all treatment groups. In addition, the integrity of the bone was maintained in mice treated with PKI 166 or PKI 166 plus Taxol, whereas massive bone destruction was seen in control and Taxol-treated mice. These results suggest that blockade of EGF-R signaling inhibits growth of RCC in the bone by its effect on tumor cells and tumor-associated endothelial cells.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Bone Neoplasms; Carcinoma, Renal Cell; Cell Division; Epidermal Growth Factor; ErbB Receptors; Humans; Kidney Neoplasms; Male; Mice; Mice, Nude; Paclitaxel; Phosphorylation; Pyrimidines; Pyrroles; Recombinant Proteins; Signal Transduction; Transforming Growth Factor alpha; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

Bi-allelic-inactivating mutations of the VHL tumor suppressor gene are found in the majority of clear cell renal cell carcinomas (VHL(-/-) RCC). VHL(-/-) RCC cells overproduce hypoxia-inducible genes as a consequence of constitutive, oxygen-independent activation of hypoxia inducible factor (HIF). While HIF activation explains the highly vascularized nature of VHL loss lesions, the relative role of HIF in oncogenesis and loss of growth control remains unknown. Here, we report that HIF plays a central role in promoting unregulated growth of VHL(-/-) RCC cells by activating the transforming growth factor-alpha (TGF-alpha)/epidermal growth factor receptor (EGF-R) pathway. Dominant-negative HIF and enzymatic inhibition of EGF-R were equally efficient at abolishing EGF-R activation and serum-independent growth of VHL(-/-) RCC cells. TGF-alpha is the only known EGF-R ligand that has a VHL-dependent expression profile and its overexpression by VHL(-/-) RCC cells is a direct consequence of HIF activation. In contrast to TGF-alpha, other HIF targets, including vascular endothelial growth factor (VEGF), were unable to stimulate serum-independent growth of VHL(-/-) RCC cells. VHL(-/-) RCC cells expressing reintroduced type 2C mutants of VHL, and which retain the ability to degrade HIF, fail to overproduce TGF-alpha and proliferate in serum-free media. These data link HIF with the overproduction of a bona fide renal cell mitogen leading to activation of a pathway involved in growth of renal cancer cells. Moreover, our results suggest that HIF might be involved in oncogenesis to a much higher extent than previously appreciated.

Topics: Basic Helix-Loop-Helix Transcription Factors; Blood; Carcinoma, Renal Cell; Cell Division; Culture Media; ErbB Receptors; Gene Expression; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Kidney Neoplasms; Mutation; Phosphorylation; Recombinant Proteins; Reverse Transcriptase Polymerase Chain Reaction; Trans-Activators; Transcription Factors; Transfection; Transforming Growth Factor alpha; Tumor Cells, Cultured; Tumor Suppressor Proteins; Ubiquitin-Protein Ligases; Von Hippel-Lindau Tumor Suppressor Protein

Renal cell carcinoma (RCC) is the most malignant urologic disease. Different lesions, such as dysplasia in the tubules adjacent to RCC, atypical hyperplasia in the cyst epithelium of von Hippel-Lindau syndrome, and adenoma have been described for a number of years as possible premalignant changes or precursor lesions of RCC. In two recent papers, kidneys adjacent to RCC or removed from other causes were analyzed, and dysplastic lesions were identified and defined in detail. Currently renal intraepithelial neoplasia (RIN) is the proposed term for classification. The criteria for a lesion to be defined as premalignant are (1) morphological similarity; (2) spatial association; (3) development of microinvasive carcinoma; (4) higher frequency, severity, and extent then invasive carcinoma; (5) progression to invasive cancer; and (6) similar genetic alterations. RIN resembles the neoplastic cells of RCC. There is spatial association. Progression to invasive carcinoma is described in experimental cancer models, and in some human renal tumors. Similar molecular alterations are found in some putative premalignant changes. The treatment for RCC is radical or partial nephrectomy. Preneoplastic lesions may remain in the renal remnant in patients treated by partial nephrectomy and may be the source of local recurrences. RIN seems to be a biologic precursor of some RCCs and warrants further investigation. Interpretation and reporting of these lesions would reveal important resources for the biological nature and clinical significance. The management of RIN diagnosed in a renal biopsy and partial nephrectomy needs to be answered.

Topics: Carcinoma, Renal Cell; ErbB Receptors; Gene Expression Regulation, Neoplastic; Humans; Immunohistochemistry; Incidence; Kidney; Kidney Neoplasms; Precancerous Conditions; Proliferating Cell Nuclear Antigen; Terminology as Topic; Transforming Growth Factor alpha; Tumor Suppressor Protein p53; United States

Mutations of the VHL tumor suppressor gene occur in patients with VHL disease and in the majority of sporadic clear cell renal carcinomas (VHL(-/-) RCC). Loss of VHL protein function is associated with constitutive expression of mRNAs encoding hypoxia-inducible proteins, such as vascular endothelial growth factor. Overproduction of angiogenic factors might explain why VHL(-/-) RCC tumors are so highly vascularized, but whether this overproduction is sufficient for oncogenesis still remains unknown. In this report, we examined the activity of transforming growth factor-alpha (TGF-alpha), another VHL-regulated growth factor. We show that TGF-alpha mRNA and protein are hypoxia-inducible in VHL(-/-) RCC cells expressing reintroduced VHL. In addition to its overexpression by VHL(-/-) RCC cells, TGF-alpha can also act as a specific growth-stimulatory factor for VHL(-/-) RCC cells expressing reintroduced wild-type VHL, as well as primary renal proximal tubule epithelial cells, the likely site of origin of RCC. This role is in contrast to those of other growth factors overexpressed by VHL(-/-) RCC cells, such as vascular endothelial growth factor and TGF-beta1, which do not stimulate RCC cell proliferation. A TGF-alpha-specific antisense oligodeoxynucleotide blocked TGF-alpha production in VHL(-/-) RCC cells, which led to the dependence of those cells on exogenous growth factors to sustain growth in culture. Growth of VHL(-/-) RCC cells was also significantly reduced by a drug that specifically inhibits the epidermal growth factor receptor, the receptor through which TGF-alpha stimulates proliferation. These results suggest that the generation of a TGF-alpha autocrine loop as a consequence of VHL inactivation in renal proximal tubule epithelial cells may provide the uncontrolled growth stimulus necessary for the initiation of tumorigenesis.

Topics: Adenocarcinoma, Clear Cell; Cell Division; Cell Hypoxia; Enzyme Inhibitors; ErbB Receptors; Gene Expression Regulation; Genes, Tumor Suppressor; Growth Substances; Humans; Insulin; Kidney Neoplasms; Ligases; Oligodeoxyribonucleotides, Antisense; Proteins; Quinazolines; Selenium; Transferrin; Transforming Growth Factor alpha; Tumor Cells, Cultured; Tumor Suppressor Proteins; Tyrphostins; Ubiquitin-Protein Ligases; von Hippel-Lindau Disease; Von Hippel-Lindau Tumor Suppressor Protein

The clear cell and the papillary types of human renal cell carcinoma (RCC) are distinct tumour entities with marked differences in their biological properties. Because growth factors are considered to affect profoundly the biological behaviour of malignant tumours, we compared the expression and function of transforming growth factor (TGF)-alpha and fibroblast growth factor (FGF) in both types of RCCs. Both in vivo and in vitro expression of TGF-alpha, epidermal growth factor-receptor (EGF-R), FGF-2 and FGF type 3- and 4-receptors was found in RCCs of both types. However, marked differences between clear cell and papillary RCCs became evident for TGF-alpha secretion, which could be demonstrated in 20 out of 24 (83%) clear cell RCCs but in only two out of four (50%) papillary tumours. Moreover, the mean TGF-alpha secretion rate in clear cell RCCs significantly (P<0. 05) exceeded that of papillary RCCs. Because the expression of growth factor receptors could not prove the corresponding signalling cascades were functional, tumour cell proliferation was tested after exposure to exogenous TGF-alpha or FGF-1. These experiments demonstrated that papillary RCCs did not respond significantly to exogenous TGF-alpha or FGF-1, whereas eight (33%) (TGF-alpha) and 11 (46%) (FGF-1) out of 24 clear cell RCCs responded with significant (P<0.05) growth stimulation. In conclusion, our investigation presents data indicating that TGF-alpha and FGF are functionally involved in the progression of clear cell RCCs, directly stimulating proliferation by autocrine and/or paracrine actions. In contrast, TGF-alpha and FGF did not directly stimulate the proliferation of our papillary RCCs, thereby suggesting functional defects or a blockade in the corresponding signalling cascades. This differential functionality might contribute to the more aggressive behaviour of clear cell RCCs.

Topics: Adenocarcinoma, Clear Cell; Adenocarcinoma, Papillary; Blotting, Northern; Carcinoma, Renal Cell; Fibroblast Growth Factors; Flow Cytometry; Humans; Immunohistochemistry; Kidney Neoplasms; Receptors, Fibroblast Growth Factor; Reverse Transcriptase Polymerase Chain Reaction; Transforming Growth Factor alpha; Tumor Cells, Cultured

The von Hippel-Lindau (VHL) tumor suppressor gene has a critical role in the pathogenesis of clear cell renal cell carcinoma (RCC), because VHL mutations have been found in both VHL disease-associated and sporadic RCC. Overexpression of transforming growth factor (TGF)-alpha has been observed in numerous RCC tumors and cell lines, and TGF-alpha has been demonstrated to support RCC cell growth through an autocrine loop. We demonstrate here that VHL substantially decreases TGF-alpha message and protein by shortening TGF-alpha mRNA half-life. By Northern analysis TGF-alpha mRNA steady-state levels were suppressed 5-fold in permanent 786-0 RCC cell lines expressing wild-type VHL compared with 786-0 cells expressing an empty vector or a mutant VHL protein lacking COOH-terminal residues 116-213 (deltaVHL). By Western analysis, VHL also substantially down-regulated the unprocessed, cell-associated Mr 20,000 TGF-alpha protein. Moreover, secreted TGF-alpha was undetectable in VHL-expressing cells. In contrast, VHL did not down-regulate the TGF-alpha receptor, epidermal growth factor receptor, either at the mRNA or protein level. Nuclear run-on in vitro transcription experiments in 786-0 cells showed that VHL did not affect transcriptional control of the endogenous TGF-alpha gene. However, actinomycin D experiments revealed a long TGF-alpha mRNA half-life in 786-0 cells that was significantly decreased by wild-type VHL but not by deltaVHL. We have, therefore, identified TGF-alpha, an important growth factor for RCC, as a new target gene for VHL and demonstrated that VHL acts by decreasing TGF-alpha mRNA stability.

Topics: Blotting, Northern; Carcinoma, Renal Cell; Cells, Cultured; Down-Regulation; ErbB Receptors; Genes, Tumor Suppressor; Half-Life; Humans; Kidney Neoplasms; Ligases; Proteins; RNA, Messenger; Transcription, Genetic; Transfection; Transforming Growth Factor alpha; Tumor Cells, Cultured; Tumor Suppressor Proteins; Ubiquitin-Protein Ligases; Von Hippel-Lindau Tumor Suppressor Protein

We demonstrate the constitutive expression of interleukin 6 (IL-6), IL-8, granulocyte-macrophage colony-stimulating factor (GM-CSF), epidermal growth factor (EGF), transforming growth factor alpha (TGF-alpha) and epidermal growth factor receptor (EGFR) in normal kidney cells, and in the majority of renal oncocytomas, papillary and non-papillary renal cell carcinomas (RCCs) by reverse transcriptase polymerase chain reaction (RT-PCR) technique. No expression of IL-6 and TGF-alpha and variable expression of GM-CSF, IL-8, EGF and EGFR was seen in chromophobe RCCs. The lack of expression of IL-6 and TGF-alpha might be correlated with the growth pattern, poor vascularity and low malignancy of chromophobe RCCs.

Topics: Carcinoma, Papillary; Carcinoma, Renal Cell; Epidermal Growth Factor; ErbB Receptors; Gene Expression; Granulocyte-Macrophage Colony-Stimulating Factor; Humans; Interleukin-6; Kidney Neoplasms; Reverse Transcriptase Polymerase Chain Reaction; Transforming Growth Factor alpha

The aim of the present study was to analyze the contribution of different stimulatory and inhibitory growth factors to the deregulated proliferation of human RCCs.. The expression of different growth factors and their corresponding receptors were analyzed by Northern blot, FACS, ELISA and immunocytochemistry in 13 permanent human RCC cell lines of the clear cell type. Moreover, the functional intactness of growth factor-related signal transduction pathways was investigated.. All RCC cell lines expressed EGF-receptor mRNA and protein and 10 cell lines secreted TGF-alpha. Exogeneously added TGF-alpha resulted in a significant (p < 0.05) stimulation of growth in 6 RCC cell lines and a significant (p < 0.05) inhibition of proliferation in 3 cell lines. PDGF B and the corresponding type beta receptor were expressed in a single cell line. mRNA expression of PDGF A and PDGF-alpha-receptor as well as IGF-1 and its receptor could not be detected in any cell line. Eleven RCC cell lines expressed TGF-beta 1 mRNA and in all cell lines TGF-beta 1 secretion into the supernatant could be demonstrated. Whereas all cell lines exhibited TGF-beta type II-receptor mRNA, type I-receptor mRNA could be detected only in 3 cell lines. TGF-beta type III-receptor was observed in 1 cell line. Exogeneously added TGF-beta1 resulted in a significant (p < 0.05) inhibition of proliferation in 7 RCC cell lines.. Clear cell RCCs exhibit a complex and heterogeneous expression pattern for various growth factors and their receptors. Growth factor secretion and intact signal transduction pathways in most clear cell RCCs facilitate an intricate modulation of RCC growth by autocrine and paracrine interactions between tumor cells and host tissue.

Topics: Carcinoma, Renal Cell; Cell Division; Epidermal Growth Factor; ErbB Receptors; Humans; Kidney Neoplasms; Platelet-Derived Growth Factor; Receptor, IGF Type 1; Receptors, Platelet-Derived Growth Factor; RNA; Transforming Growth Factor alpha; Transforming Growth Factor beta; Tumor Cells, Cultured

Expression and prognostic impact of some exponents of the epidermal growth factor (EGF) family in renal cell carcinoma (RCC) were examined.. EGF, transforming growth factor-alpha (TGF-alpha), EGF receptor (EGF-R), and c-erb B-2 were determined immunohistochemically in formalin-fixed paraffin-embedded tumor samples of 30 patients with locally confined RCCs. The prognostic significance of these growth factors and their receptors as well as of tumor stage and malignancy grade was examined with respect to survival and tumor recurrence by following up the fate of the patients after nephrectomy (mean follow-up time 5.2 years).. The members of the EGF family and their receptors studied were expressed to a variable degree in all RCCs investigated. However, using log-rank tests in Kaplan-Meier plots only tumor stage (p < 0.0007) and malignancy grade (p < 0.007) but none of the growth factors or receptors studied (p > 0.05, respectively) exhibited prognostic significance with respect to both survival and disease-free period. On the contrary, there was a significant correlation between EGF and TGF-alpha (p < 0.001), EGF and EGF-R (p = 0.028), EGF-R and c-erb B-2 (p = 0.0009), and-inversely related-between TGF-alpha and tumor stage (p = 0.047) and between EGF-R and malignancy grade (p = 0.03). The coexpression of the factors studied also showed no prognostic relevance.. The expression of these members of the EGF family seems not to bear evaluable prognostic information for clinical use in the case of RCC.

Topics: Adult; Aged; Carcinoma, Renal Cell; Epidermal Growth Factor; ErbB Receptors; Female; Follow-Up Studies; Gene Expression Regulation, Neoplastic; Genes, erbB-2; Humans; Immunohistochemistry; Kidney Neoplasms; Male; Middle Aged; Neoplasm Recurrence, Local; Nephrectomy; Prognosis; Receptor, ErbB-2; Retrospective Studies; Transforming Growth Factor alpha

Transforming growth factor-alpha (TGF-alpha) is a multifunctional cell regulatory protein with a wide range of effects on cell growth and differentiation and has been implicated in the neoplastic transformation of a variety of cell types. Altered expression of TGF-alpha and its cognate receptor (epidermal growth factor receptor) is enhanced in human and rat renal cell carcinomas. The objective of the study reported here was to determine whether altered TGF-alpha expression is an early or late event in renal tubular oncogenesis. The immunohistochemical expression of TGF-alpha was studied in preneoplastic renal tubular lesions in a rat model of hereditary renal cell carcinoma. Strong TGF-alpha immunoreactivity was present at all stages of renal cell tumor development, including the earliest detectable dysplasias. In contrast, the non-neoplastic regenerating tubular epithelium of rat degenerative nephropathy did not stain for TGF-alpha, although this tissue exhibited a proliferative capacity similar to that observed in the dysplastic and neoplastic lesions. This study indicated that altered TGF-alpha expression was detectable early in the development of renal cell tumors and may be an important feature of the transformed phenotype.

Topics: Animals; Bromodeoxyuridine; Carcinoma, Renal Cell; Cell Division; Epithelial Cells; Epithelium; Kidney Neoplasms; Kidney Tubules; Phenotype; Precancerous Conditions; Rats; Rats, Inbred Strains; Transforming Growth Factor alpha

Growth factor receptor-signaling pathways are potentially important targets for anticancer therapy. The interaction of anticancer agents with specific molecular targets can be identified by correlating target expression patterns with cytotoxicity patterns. We sought to identify new agents that target and inhibit the activity of the epidermal growth factor (EGF) receptor and of c-erbB2 (also called HER2 or neu), by correlating EGF receptor, transforming growth factor (TGF)-alpha (a ligand for EGF receptor), and c-erbB2 messenger RNA (mRNA) expression levels with the results of cytotoxicity assays of the 49000 compounds in the National Cancer Institute (NCI) drug screen database.. The levels of mRNAs were measured and used to generate a molecular target database for the 60 cell lines of the NCI anticancer drug screen. The computer analysis program, COMPARE, was used to search for cytotoxicity patterns in the NCI drug screen database that were highly correlated with EGF receptor, TGF-alpha, or c-erbB2 mRNA expression patterns. The putative EGF receptor-inhibiting compounds were tested for effects on basal tyrosine phosphorylation, in vitro EGF receptor tyrosine kinase activity, and EGF-dependent growth. Putative ErbB2-inhibiting compounds were tested for effects on antibody-induced ErbB2 tyrosine kinase activity.. EGF receptor mRNA and TGF-alpha mRNA levels were highest in cell lines derived from renal cancers, and c-erbB2 mRNA levels were highest in cells derived from breast, ovarian, and colon cancers. Twenty-five compounds with high correlation coefficients (for cytotoxicity and levels of the measured mRNAs) were tested as inhibitors of the EGF receptor or c-erbB2 signaling pathways; 14 compounds were identified as inhibitors of these pathways. The most potent compound, B4, inhibited autophosphorylation (which occurs following activation) of ErbB2 by 50% in whole cells at 7.7 microM.. Novel EGF receptor or c-erbB2 pathway inhibitors can be identified in the NCI drug screen by correlation of cytotoxicity patterns with EGF receptor or c-erbB2 mRNA expression levels.

Topics: Antineoplastic Agents; Breast Neoplasms; Cell Division; Cell Line; Cluster Analysis; Colonic Neoplasms; Drug Screening Assays, Antitumor; Epidermal Growth Factor; ErbB Receptors; Female; Gene Expression Regulation, Neoplastic; Humans; Kidney Neoplasms; Ovarian Neoplasms; Receptor, ErbB-2; RNA, Messenger; Structure-Activity Relationship; Transcription, Genetic; Transforming Growth Factor alpha; Tumor Cells, Cultured

To characterize the expression of transforming growth factor-alpha (TGF-alpha) in various histologic types of renal cell carcinomas.. Immunohistochemistry of renal cell carcinoma and adjacent normal tissue was performed on formalin-fixed tissue using a specific monoclonal antibody to TGF-alpha.. Clear and distinct staining was present in normal distal convoluted tubules and collecting ducts. The growth factor was not observed in the glomerulus or the proximal tubule. In tumors composed of clear cells, staining was evident only in endothelial cells but not in the tumor cells themselves. In granular cell type tumors, the tumor cells as well as endothelial cells stained for TGF-alpha. When mixed cell type tumors were studied, a heterogenous pattern of growth factor expression was found. Endothelial cells and granular cells but not clear cells demonstrated positive staining.. These studies suggest that TGF-alpha is likely to play a major role in neovascularization of clear cell carcinomas and that the growth factor may be more important in supporting proliferation of granular cell type tumors.

Topics: Carcinoma, Renal Cell; Gene Expression Regulation, Neoplastic; Humans; Kidney Neoplasms; Transforming Growth Factor alpha

This study explores the role played by TGF alpha in estrogen-induced renal tumors. Tumors were induced in male Syrian hamster by chronic administration of diethylstilbestrol (DES). Six experimental groups (n = 5-9) were chronically exposed to DES and sacrificed after 1, 2, 4, 6, 9 and 11 months, respectively. In the course of treatment, the nephrons were the site of an important increase of cell turnover, which was characterized by a process of hyperplasia/dysplasia in proximal tubules preceding the neoplastic transformation. In treated animals and in controls, the analysis of renal tissue by Western blot revealed the presence of a 6 kDa polypeptide crossreacting with anti-TGF alpha antibody. In controls, TGF alpha immunoreactivity was localized in proximal and in distal tubules. Before tumor development (1-4 months), TGF alpha RIA showed an increase of TGF alpha concentration in renal tissue, in parallel with the increased cell proliferation observed in proximal tubules. In addition, Western blot analysis also demonstrated in kidney tissue the presence of a 165 kDa protein displaying the immunoreactivity of EGF/TGF alpha receptor. The receptor immunoreactivity was localized in proximal tubular cells suggesting an involvement of TGF alpha in tubular epithelial growth through autocrine or paracrine pathways. In large neoplasms, immunocytochemistry revealed only clusters of transformed cells intensely stained by the anti-TGF alpha antibody. These cells displayed the appearance of stellate or polyhedric cells infiltrating adjacent neoplastic tissues. Antisera raised against intra- or extracytoplasmic domains of the EGF/TGF alpha receptor were assayed to localize this receptor in the tumors. In contrast with tubular structures, immunoreactivity to EGF/TGF alpha receptor was never detected in tumoral tissue. The apparent absence of EGF/ TGF alpha receptor immunoreactivity in malignant cells seems to exclude an involvement of this growth factor in the tumorigenic process, although it could be involved in tumor neovascularization.

Topics: Amino Acid Sequence; Animals; Blotting, Western; Carcinogens; Cell Division; Cricetinae; Diethylstilbestrol; ErbB Receptors; Immunohistochemistry; Kidney Neoplasms; Kidney Tubules, Proximal; Male; Mesocricetus; Molecular Sequence Data; Radioimmunoassay; Transforming Growth Factor alpha

Renal cell carcinoma (RCC) is thought to arise from the renal tubular cells (RTC). Assuming that proliferating RTC imply a premalignant change of RTC into RCC, messenger RNA expressions of growth factors in cultured RTC were compared to both cultured and frozen noncultured RCC.. The expression of transforming growth factor-alpha (TGF-alpha), epidermal growth factor (EGF), EGF receptor (EGFR) and interleukin-6 (IL-6) were studied in surgically obtained RCC (n = 17), cultured RCC (n = 10), and autologous cultured RTC (n = 15). Quantitation of the PCR product was performed using a computer image analyzer which evaluated the intensity of each cytokine relative to beta-actin.. TGF-alpha, EGFR and IL-6 were detected in most of the cultured RTC, and both cultured and noncultured RCC were also expressed at high levels. In contrast to a high positivity of TGF-alpha, EGF was not strongly positive in all specimens.. Our results show that there is a predominant autocrine production of TGF-alpha in RCC and RTC, suggesting that TGF-alpha plays a distinct role in the proliferation of these cells. These studies also indicate that the mechanisms of proliferation and cytokine production of RCC and RTC are similar.

Topics: Carcinoma, Renal Cell; Cell Division; Epidermal Growth Factor; Gene Expression; Humans; Immunohistochemistry; Interleukin-6; Kidney Neoplasms; Kidney Tubules; Polymerase Chain Reaction; RNA, Messenger; RNA, Neoplasm; Transforming Growth Factor alpha; Tumor Cells, Cultured

Papillary renal carcinomas are a cytogenetically unique subset of renal carcinomas that have been reported to be clinically less aggressive. We have examined 19 papillary tumors for immunohistochemical expression of the epidermal growth factor receptor (EGF-R) and its ligand, transforming growth factor alpha (TGF-alpha). EGF-R and TGF-alpha expression was also studied in 149 nonpapillary tumors and 7 mixed papillary/solid tumors. EGF-R and TGF-alpha expression were compared to histology, stage, metastatic behavior, and survival. Formalin-fixed, paraffin-embedded nephrectomy specimens collected between 1977 and 1986 were stained with antibodies to EGF-R and TGF-alpha. Patients with papillary tumors were found to present with earlier stage disease and had significantly longer survival. Papillary tumors had a significantly lower rate of EGF-R positivity than solid pattern tumors (21% versus 73%, P < 0.001). Intermediate or strong cell membrane immunoreactivity for EGF-R was associated with high tumor grade and poor disease-specific survival. EGF-R positivity in the primary tumor was associated with the presence of metastatic disease and with metastatic spread to lung versus bone. Tumor parenchymal TGF-alpha staining was present in 50% of the cases and was not associated with stage or grade. Unrelated to tumor parenchymal TGF staining, tumor vessels stained for TGF-alpha in 56% of the cases. Vessel TGF-alpha staining was absent in papillary tumors (P < 0.001). The improved clinical behavior of papillary tumors as compared to nonpapillary renal tumors may be related, in part, to their relatively lower levels of EGF-R expression.

Topics: Adult; Aged; Aged, 80 and over; Biomarkers, Tumor; Carcinoma, Papillary; Carcinoma, Renal Cell; Disease-Free Survival; ErbB Receptors; Female; Follow-Up Studies; Humans; Immunohistochemistry; Kidney Neoplasms; Male; Middle Aged; Neoplasm Metastasis; Neoplasm Staging; Prognosis; Survival Analysis; Time Factors; Transforming Growth Factor alpha

Immunohistochemical stains using antibody to epidermal growth factor receptor (EGFR) and transforming growth factor alpha (TGF-alpha) were applied to 67 cases of renal cell carcinoma retrieved from the files of the Division of Surgical Pathology. The 64 patients (33 females, 31 males) ranged in age from 35 to 87 years (mean, 61 years). Two patients had more than one renal carcinoma included in this study. Fifty-seven cases (85%) expressed EGFR, with staining largely confined to the cell membrane. Staining intensity was directly correlated with tumor grade (P = 0.02, T test), size (P = 0.04), and stage (P = 0.01). Those cases with more intense EGFR staining also appear to have shorter patient survival than those showing less intense staining (43 mo versus 63 mo, P = 0.05). Forty-nine cases (73%) expressed TGF-alpha in a distribution similar to that of EGFR. There was no significant correlation between TGF-alpha staining intensity and tumor size, stage, or grade. When the tumor expressed either EGFR or TGF-alpha but not both proteins, average patient survival was 38 months, while the average survival of those patients whose tumors expressed both EGFR and TGF-alpha was 61 months (P = 0.04). Three of eleven cases, all of which expressed EGFR, were felt to show EGFR gene amplification using a modification of the differential polymerase chain reaction on archival, formalin-fixed, paraffin-embedded tissue. EGFR and TGF-alpha likely play a role in the progression of renal cell carcinoma, and their coexpression may have favorable prognostic implications.

Topics: Adult; Aged; Aged, 80 and over; Carcinoma, Renal Cell; ErbB Receptors; Female; Humans; Immunoenzyme Techniques; Kidney Neoplasms; Male; Middle Aged; Polymerase Chain Reaction; Prognosis; Survival Rate; Transforming Growth Factor alpha

Accumulation of sulfolipids associated with markedly elevated levels of glycolipid sulfotransferase activities was previously demonstrated in human renal cell carcinoma cells. To explore the regulation mechanisms of sulfoglycolipid synthesis in renal cancer, effects of various growth factors on the metabolic enzymes of sulfoglycolipids were investigated by using a human renal cell carcinoma cell line, SMKT-R3. Among the growth factors tested, transforming growth factor alpha (TGF-alpha) and epidermal growth factor (EGF) were found to increase the sulfotransferase activity markedly (about 300%), but did not change that of arylsulfatase A, which hydrolyzes sulfoglycolipids. The augmented effects of TGF-alpha was abolished by cycloheximide. Since TGF-alpha is known to bind to the same receptor as EGF, SMKT-R3 cells were investigated for the EGF receptor by affinity cross-linking with 125I-EGF. A radiolabeled protein with a molecular mass of 175 kDa corresponding to the ligand-receptor complex was immunoprecipitated with a monoclonal anti-EGF receptor antibody. When production of the growth factors was examined immunochemically, the cells were found to secrete TGF-alpha at a low level and retain it in a membrane-bound form, whereas EGF was not detected. These observations suggest that the sulfotransferase activities are regulated through the autocrine, paracrine, and/or juxtacrine modes of intercellular stimulation by TGF-alpha in human renal cancer cells.

Topics: Carcinoma, Renal Cell; Cerebroside-Sulfatase; Enzyme Activation; ErbB Receptors; Humans; Kidney Neoplasms; Sulfotransferases; Transforming Growth Factor alpha; Tumor Cells, Cultured

Transforming growth factor alpha production by renal tumors, acting through the epidermal growth factor receptor, has been implicated in malignant transformation by studies which compared gene expression in neoplastic and normal human tissue. We sought confirmation of this hypothesis by measuring the growth responses of a human renal tumor cell line to the addition of epidermal growth factor and transforming growth factor alpha. Surprisingly, it was found that both growth factors could induce either mitogenic or inhibitory signals depending on the growth status of the cultures. Confluent cultures were stimulated by both growth factors, and nonconfluent cultures were inhibited, as determined by thymidine incorporation, cell cycle analysis, and direct cell counting. These signals appear to use different transduction pathways, as growth factor induced inhibition was reversed by Bordetella pertussis toxin (which affects G protein signaling), whereas the stimulatory effects were not reversed. Two clones isolated from these cells responded in the same manner as the main cell isolate. These data show that the same cell may display opposite responses to equivalent concentrations of the same growth factor, depending on the transduction pathway used after triggering by receptor occupancy of either ligand (epidermal growth factor or transforming growth factor alpha).

Topics: Adenocarcinoma; Cell Count; Cell Division; Dose-Response Relationship, Drug; Epidermal Growth Factor; Humans; Kidney Neoplasms; Pertussis Toxin; Transforming Growth Factor alpha; Tumor Cells, Cultured; Virulence Factors, Bordetella

Cellular differentiation and mRNA levels of genes involved in kidney growth were investigated in normal kidney cells, cyst-lining epithelial cells of polycystic kidney disease, and renal carcinoma cells (RCC). All cells comparatively studied exhibited an antigenic phenotype of proximal tubular cells as shown by the expression of a panel of brush border membrane enzymes and kidney-associated cell surface antigens. The epithelial developmental antigen Exo-1 was expressed in 50% to 80% of cyst-lining epithelia in polycystic kidney tissue and in 20% to 30% of polycystic kidney cells cultured in vitro. Normal kidney cells and RCC were negative under identical culture conditions. The expression of antigen Exo-1 is associated with hyperproliferation in an epithelial tissue compartment composed of cells which have not yet reached their terminal differentiation state. Increased amounts of mRNA of the growth factor receptor system of epidermal growth factor (EGF) receptor and its ligand transforming growth factor (TGF)-alpha were associated with the malignant phenotype of RCC. Increased expression of EGF receptor and TGF-alpha, although less prominent, were also observed in polycystic kidney cells compared with normal kidney cells. In conclusion, the expression of Exo-1 in cyst-lining epithelial cells of autosomal dominant polycystic kidney disease (ADPKD) and the altered regulation of TGF-alpha and EGF receptor in these cells contribute to the hypothesis that hyperproliferation is an underlying pathogenic mechanism of ADPKD.

Topics: Antibodies, Monoclonal; Antigens, Differentiation; Antigens, Surface; Carcinoma, Renal Cell; Cells, Cultured; Epithelium; ErbB Receptors; Gene Expression; Genes; Growth Substances; Humans; Immunohistochemistry; Kidney; Kidney Neoplasms; Polycystic Kidney, Autosomal Dominant; Proto-Oncogene Proteins c-myc; RNA, Messenger; Transforming Growth Factor alpha

A hereditary form of renal cell carcinoma exists in rats that results from a single gene mutation and is histologically similar to that described in humans. Cell lines derived from these rat tumors were shown to express abundant transforming growth factor-alpha (TGF-alpha) and epidermal growth factor (EGF)-receptor RNA transcripts, but no EGF mRNA. In contrast, normal kidney expressed EGF and EGF-receptor transcripts, but TGF-alpha transcripts were barely detectable. Other kidney epithelial cell lines examined (NRK 52E, MDCK, and LLCPK) were negative for expression of both TGF-alpha and EGF transcripts, but expressed EGF receptors. In addition, the renal cell carcinoma-derived lines secreted TGF-alpha into the media. Immunohistochemistry of normal kidney with a TGF-alpha specific antibody revealed a characteristic pattern of staining of collecting ducts and, to a lesser degree, proximal tubules. In the neoplastic kidney tissue, both the cystic and solid portions of the tumors displayed intense immunoreactivity, indicating that altered expression of this growth factor by the transformed cells occurred in situ. These results suggest that altered TGF-alpha expression is an important aspect of the neoplastic phenotype in rodent as well as human renal cell carcinoma, and support the use of this hereditary rodent tumor model for studying the pathogenesis of this disease.

Topics: Animals; Carcinoma, Renal Cell; Epidermal Growth Factor; ErbB Receptors; Kidney; Kidney Neoplasms; Phenotype; Rats; RNA, Messenger; Transforming Growth Factor alpha

Transforming growth factors (TGFs)-alpha and -beta are regulatory polypeptides that reversibly confer a transformed phenotype upon normal cultured fibroblasts. TGF-alpha is synthesized primarily by malignant cells and shares many properties with the tissue mitogen, epidermal growth factor (EGF). The expression of TGF-beta mRNA has been demonstrated in a variety of normal and malignant cell types, some of which secrete the mature protein in an inactive form. To investigate the role of TGFs in human renal cell carcinoma (RCC), we used two renal tumor-derived cell lines and one established RCC cell line for analysis of TGF-alpha and TGF-beta mRNA production and for evaluation of TGF-beta protein secretion. By northern blot hybridization, all three RCC cell lines expressed TGF-alpha and -beta mRNA. In addition, TGF-beta activity was found in the conditioned medium from these cells. The secreted TGF-beta protein, however, displayed biological activity only after activation by acid-treatment. These data demonstrate the constitutive expression of TGF-alpha and -beta mRNA by RCC cell lines and, also, the secretion by this tumor of endogenous TGF-beta protein in a latent form.

Topics: Carcinoma, Renal Cell; Cell Line; Gene Expression; Humans; Kidney Neoplasms; Radioligand Assay; RNA, Messenger; Transforming Growth Factor alpha; Transforming Growth Factor beta; Tumor Cells, Cultured