cyclic-gmp and Carcinoma--Squamous-Cell

Head and neck squamous cell carcinoma (HNSCC) is an aggressive disease with high mortality. Treatments, which can result in significant morbidity, have not substantially changed in three decades. The second messenger cyclic GMP (cGMP), which targets protein kinase G (PKG), is generated by guanylate cyclases (GCs), and is rapidly hydrolyzed by phosphodiesterases (PDEs). Activation of the cGMP/PKG pathway is antineoplastic in several cancer types, but its impact on HNSCC has not been fully exploited. We found differential expression of critical components of this pathway in four HNSCC cell lines. Several activators of soluble GC (sGC), as well as inhibitors of PDE5, increased intracellular cGMP, reduced cell viability, and induced apoptosis in HNSCC cells. The apoptotic effects of the sGC activator BAY 41-2272 and the PDE5 inhibitor Tadalafil (Cialis) were mediated by PKG. Furthermore, Tadalafil substantially reduced the growth of CAL27-derived tumors in athymic mice. Several drugs which either activate sGC or inhibit PDE5 are approved for treatment of nonmalignant conditions. These drugs could be repurposed as novel and effective therapeutics in patients with head and neck cancer.

Topics: Animals; Apoptosis; Carcinoma, Squamous Cell; Cell Line, Tumor; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Female; Guanylate Cyclase; Head and Neck Neoplasms; Humans; Mice; Phosphodiesterase 5 Inhibitors; Pyrazoles; Pyridines; Signal Transduction; Squamous Cell Carcinoma of Head and Neck; Tadalafil

We previously reported that human squamous cell carcinoma (SCC) cell lines refractory to cis-diaminedichloro-platinum II (cisplatin [CDDP]) had significant upregulation of the phosphodiesterase 3B gene (PDE3B), suggesting that inhibiting PDE3B suppresses CDDP resistance. shRNA-mediated PDE3B depletion in CDDP-resistant cells derived from SCC cells and Hela cells and induced CDDP sensitivity and inhibited tumor growth with elevated cyclic GMP induction resulting in upregulation of the multidrug-resistant molecule, but this did not occur in the 5-fluorouracil-resistant hepatocellular carcinoma cell lines. Furthermore, the antitumor growth effect of the combination of a PDE3B inhibitor (cilostazol) and CDDP in vivo was also greater than with either cilostazol or CDDP alone, with a significant increase in the number of apoptotic and cell growth-suppressive cancer cells in CDDP-resistance cell lines. Our results provided novel information on which to base further mechanistic studies of CDDP sensitization by inhibiting PDE3B in human cancer cells and for developing strategies to improve outcomes with concurrent chemotherapy.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Body Weight; Carcinoma, Squamous Cell; Cilostazol; Cisplatin; Cyclic AMP; Cyclic GMP; Cyclic Nucleotide Phosphodiesterases, Type 3; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Female; Gene Expression Regulation, Enzymologic; Gene Silencing; HeLa Cells; Humans; Mice; Mice, Nude; Phosphodiesterase 3 Inhibitors; RNA, Messenger; Tetrazoles; Tumor Cells, Cultured; Uterine Cervical Neoplasms; Xenograft Model Antitumor Assays

VILIP-1 (visinin-like protein 1) is downregulated in various human squamous cell carcinoma (SCC). In a mouse skin SCC model VILIP-1 expression is reduced in aggressive tumor cells, accompanied by reduced cAMP levels. Overexpression of VILIP-1 in aggressive SCC cells led to enhanced cAMP production, in turn causing a reduction in invasive properties. Moreover, in primary neurons and neuronal tumor lines VILIP-1 enhanced cGMP signaling. Here, we set out to determine whether and how cAMP and cGMP signaling contribute to the VILIP-1 effect on enhanced SCC model cell migration, and thus most likely invasiveness in vivo. We found stronger increase in cGMP levels in aggressive, VILIP-1-negative SCC cells following stimulation of guanylyl cyclases NPR-A and -B with the natriuretic peptides ANP and CNP, respectively. Incubation with ANP or 8Br-cGMP to increase cGMP levels further enhanced the migration capacity of aggressive cells, whereas cell adhesion was unaffected. Increased cGMP was caused by elevated expression levels of NPR-A and -B. However, the expression level of VILIP-1 did not affect cGMP signaling and guanylyl cyclase expression in SCC. In contrast, VILIP-1 led to reduced migration of aggressive SCC cells depending on cAMP levels as shown by use of adenylyl cyclase (AC) inhibitor 2',3'-dideoxyadenosine. Involvement of cAMP-effectors PKA and EPAC play a role downstream of AC activation. VILIP-1-positive and -negative cells did not differ in mRNA expression of ACs, but an effect on enhanced protein expression and membrane localization of ACs was shown to underlie enhancement of cAMP production and, thus, reduction in cell migration by VILIP-1.

Topics: Adenylyl Cyclase Inhibitors; Adenylyl Cyclases; Animals; Atrial Natriuretic Factor; Blotting, Western; Carcinoma, Squamous Cell; Cell Adhesion; Cell Line, Tumor; Cell Movement; Cyclic AMP; Cyclic GMP; Dideoxyadenosine; Guanosine Monophosphate; Humans; Mice; Microscopy, Fluorescence; Neurocalcin; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Signal Transduction; Skin Neoplasms

The aim of the present study was to assess the role of the p38 mitogen-activated protein kinase (MAPK) pathway in the induction of inducible nitric oxide synthase (iNOS) expression and the production of NO by neutrophils (polymorphonuclear neutrophils [PMNs]) and peripheral blood mononuclear cells (PBMCs) in patients with squamous cell carcinoma (SCC) of the oral cavity.. PMNs and PBMCs were isolated from 24 patients with SCC. The expression of iNOS and phospho-p38 MAPK was estimated by Western blotting. Total NO was measured in the cell supernatants and serum using the Griess method. The generation of superoxide anion radicals by the cells was estimated using the cytochrome-c reduction test. The cyclic guanosine monophosphate level in the cell supernatants and plasma was assessed using an enzyme-linked immunosorbent assay kit, and the concentrations of malonyldialdehyde in serum were assessed using a thiobarbituric acid method.. The results of the present study of patients with stage II and III disease showed lowered expression of iNOS and phospho-p38 MAPK in PMNs and PBMCs. Moreover, in these patients, a lower production of NO by PMNs and PBMCs was observed. However, the opposite relationship was observed between the expression of phospho-p38 MAPK and iNOS in the leukocytes of patients with stage IV disease. The concentration of total NO in the PMN and PBMC supernatants of patients with advanced disease stages did not differ from that of the control group. In all the patients with SCC, a lowered ability of neutrophils to generate superoxide anion radicals and an increased production of cyclic guanosine monophosphate by PMNs and PBMCs was confirmed. Furthermore, a greater concentration of cyclic guanosine monophosphate was found in the plasma and total NO in the serum of patients with stage IV disease compared with the levels in the control group. A greater concentration of malonyldialdehyde in the serum of all patients compared with that in the control group was also observed.. Our results indicate that in the leukocytes of patients with stage II and III SCC, the p38 MAPK pathway performs an essential role in the induction of iNOS expression, and the process of lipid peroxidation is not dependent on NO. In contrast, in patients with advanced-stage SCC, iNOS expression did not seem to be linked with the p38 MAPK pathway, and NO directly influenced the process of lipid peroxidation.

Topics: Adult; Carcinoma, Squamous Cell; Case-Control Studies; Cyclic GMP; Enzyme Induction; Humans; Leukocytes, Mononuclear; Lipid Peroxidation; Malondialdehyde; Middle Aged; Mouth Neoplasms; Neutrophils; Nitric Oxide; Nitric Oxide Synthase Type II; p38 Mitogen-Activated Protein Kinases; Reference Values; Second Messenger Systems; Severity of Illness Index; Signal Transduction; Young Adult

Within 24 h four peptide hormones, i.e. vessel dilator, long acting natriuretic peptide, kaliuretic peptide, and atrial natriuretic peptide and their intracellular mediator cyclic GMP decreased the number of human squamous lung cancer cells 51, 22, 25, 21, and 30%, respectively. There was not any proliferation in the 3 days following this decrease in cell number. Vessel dilator decreased DNA synthesis 85% in the squamous lung cancer cells. Thus, vessel dilator significantly decreased the number of human squamous lung cancer cells and their DNA synthesis, mediated in part by cyclic GMP, more than other peptide hormones.

Topics: Atrial Natriuretic Factor; Carcinoma, Squamous Cell; Cell Proliferation; Cyclic GMP; DNA Replication; DNA, Neoplasm; Humans; Lung Neoplasms; Peptide Fragments; Protein Precursors; Tumor Cells, Cultured

Approximately 310,000 new cases of oral and pharynx cancer account for a major cause of neoplasm related morbidity and mortality world-wide. Unfortunately, the survival rate has not improved significantly in the last decade. The vast majority of head and neck cancer is squamous cell carcinoma. The major adhesion-proteins involved in the development and maintenance of all solid tissue are the Cadherins. Cadherins are the transmembrane components of the adherent junction with interaction with plakoglobin and beta-catenin. Downregulation of Cadherins and catenins is frequently observed in many types of human cancer. Sulindac sulfone is one of the new therapeutic apoptotic agents that show promise in the treatment of cancer. In this study, we incubated sulindac sulfone with a head and neck cancer cell line and investigated the outcome of E-Cadherin. Immunohistochemical and Western blot analyses were then performed, with different concentrations of sulindac sulfone (100, 200, 400, 600, and 800 microMol) for 48 h. At 400 microMol of sulindac sulfone a decrease of 21% was observed; at 600 microMol, 44% decrease of beta-catenin concentration was seen, and incubation with 800 microMol resulted in 73% reduction of secreted beta-catenin. Incubation with sulindac sulfone seemed to stop proliferation; however, with respect to the controls, there was no increased reduction of the total protein. Sulindac sulfone resulted in an increase of E-Cadherin content in the head and neck squamous cell cancer cell line after 48 h of incubation; however, the reactivity was restricted to the adherent junctions. At increasing concentrations of sulindac sulfone, intercellular E-Cadherin immunostaining intensifyied. ELISA also depicted significant rising levels of E-Cadherin. Sulindac sulfone contributes to the inactivation of cGMP phospho-diesterase. Thus, the accumulation of cellular cGMP and protein kinase G is induced. The following degradation of the phosphorylated beta-catenin and the dissociation from the Cadherin-catenin complex releases E-Cadherin. This may also contribute to growth inhibition and co-ordinate with apoptosis induction. It is not really clear as to, which pathway results in the elevation of the E-Cadherin proteins. However, in epithelial cancer cells, the Cadherin-catenin complex serves as a target for the chemopreventive agent, sulindac sulfone.

Topics: 3',5'-Cyclic-GMP Phosphodiesterases; Antineoplastic Agents; Apoptosis; beta Catenin; Cadherins; Carcinoma, Squamous Cell; Cell Adhesion; Cyclic GMP; Head and Neck Neoplasms; Humans; Immunohistochemistry; Protein Kinase C; Sulindac; Tumor Cells, Cultured; Up-Regulation

In order to examine the cyclic nucleotides (cGMP) role in carcinoma growth and invasivity. We analyzed two cell lines, LSHT29 and 17GT, and tissues in patients with carcinoma and malignant tissues with (N+) and without (N-) lymph node metastases. Higher cGMP levels in pathological samples suggest a strong correlation between intracellular cGMP concentration and carcinoma progression.

Topics: Carcinoma; Carcinoma, Squamous Cell; Cell Line, Tumor; Chromatography, High Pressure Liquid; Cyclic GMP; Disease Progression; Gingival Neoplasms; Guanosine Monophosphate; Humans; Indicators and Reagents; Lymphatic Metastasis; Mouth Neoplasms; Quinolines

Cyclic guanosine monophosphate (cGMP) is an essential second messenger metabolized by phosphodiesterases (PDEs).. We looked for a possible correlation of PDE activities in human oral squamous cell carcinoma (OSCC) with and without lymph node metastases.. The analysis of phosphodiesterase activity and the cGMP assay were done by reverse-phase HPLC on samples of fresh or frozen gingival tissues. Analysis of cGMP was confirmed with the enzyme-linked immunoabsorption assay.. cGMP PDE activity was 34.92 +/- 7.17 SD, 12.89 +/- 4.43 SD, and 35.88 +/- 8.76 SD (nmols/mg of protein), respectively, in controls, samples without lymph node involvement (N-), and specimens with lymph node metastases (N+). cGMP values were 1.97 +/- 0.63 SD, 3.30 +/- 1.47 SD, and 3.49 +/- 1.47 SD (nmols/mg of protein). Our data support the hypothesis of a role for cGMP and PDE in the progression of OSCC.

Topics: 3',5'-Cyclic-GMP Phosphodiesterases; Carcinoma, Squamous Cell; Cyclic GMP; Disease Progression; Gingiva; Gingival Neoplasms; Humans; Lymph Nodes; Lymphatic Metastasis; Second Messenger Systems; Statistics as Topic

Numerous reports have documented a direct involvement of matrix metalloproteinase (MMP) overexpression in the development and progression of head and neck squamous cell carcinoma (HNSCC). In this study, the authors examined whether the expression of MMPs in HNSCC is correlated with other steps involved in tumor growth and metastasis, like angiogenesis, activation the nitric oxide (NO) pathway, and alteration of the p53 tumor suppressor gene.. MMP-1, MMP-2, and MMP-9 expression levels were examined immunohistochemically in samples from 43 patients with HNSCC. Microvessel density (MVD) was determined by immunostaining of endothelial cells with anti-CD31 monoclonal antibody. Inducible nitric oxide synthase (iNOS) activity and cyclic guanosine monophosphatate (cGMP) levels were assessed in fresh tumor samples, whereas exons 5-9 of the p53 gene were analyzed by reverse transcriptase-polymerase chain reaction, single-strand conformation polymorphism analysis and were sequenced.. MMP-1 overexpression (>10% of tumor cells) was identified in 32 tumors (74.5%), whereas elevated levels of MMP-2 and MMP-9 were detected in 17 tumors (39.5%) each. Tumors with MMP-9 overexpression were characterized by significantly higher MVD (P = 0.05) and significantly higher iNOS activity and cGMP levels (P = 0.005 and P = 0.02, respectively). Moreover, p53 mutation was associated strongly with MMP-9 overexpression (P = 0.004). Conversely, no correlation was found between MMP-1 and MMP-2 expression, angiogenesis, iNOS activity, cGMP levels, and p53 mutation in this series.. This study documents the existence of a correlation between MMP-9 expression, activity of the iNOS pathway, p53 status, and angiogenesis in patients with HNSCC. This raises the possibility that p53 mutation, which frequently is present in HNSCC, may result in increased angiogenesis and invasiveness related to increased nitric oxide and MMP production by tumor cells, ultimately contributing to tumor progression.

Topics: Carcinoma, Squamous Cell; Cyclic GMP; Genes, p53; Head and Neck Neoplasms; Humans; Immunohistochemistry; Laryngeal Neoplasms; Matrix Metalloproteinase 1; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Matrix Metalloproteinases; Microcirculation; Mouth Neoplasms; Mutation; Neovascularization, Pathologic; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Oropharyngeal Neoplasms

We investigated the interactions between inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) pathways in head and neck squamous cell carcinomas (HNSCCs) and in two carcinoma cell lines. HNSCCs showed an up-regulation of both pathways which were strongly correlated with each other (p=0.02) and with tumor vascularization (p=0.0001 and p=0.008, respectively). In carcinoma cells, Escherichia coli lipopolysaccharide (LPS) and EGF treatment up-regulated both pathways. NOS inhibitor N(G)-monomethyl-L-arginine methyl ester (L-NAME) inhibited this up-regulation. LPS or EGF induced iNOS expression that was not altered by NOS or COX-2 inhibitors. Conversely, LPS or EGF promoted COX-2 expression that was decreased by L-NAME. The NO donor S-nitroso-acetyl-penicillamine (SNAP) up-regulated COX-2 pathway and this effect was reduced by the guanylate cyclase inhibitor methylene blue. Thus, in squamous carcinoma cells, NO increases the activity of COX-2 pathway and this effect is probably mediated by endocellular cGMP level, with potential implications on tumor growth, angiogenesis, and therapy.

Topics: Carcinoma, Squamous Cell; Cyclic GMP; Cyclooxygenase 2; Enzyme Activation; Epidermal Growth Factor; Head and Neck Neoplasms; Humans; Isoenzymes; Lipopolysaccharides; Membrane Proteins; Neovascularization, Pathologic; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Prostaglandin-Endoperoxide Synthases; S-Nitroso-N-Acetylpenicillamine; Signal Transduction; Statistics as Topic; Tumor Cells, Cultured; Up-Regulation

Angiogenesis (formation of new blood vessels) is associated with tumor growth and metastasis in patients with solid tumors, including those of the head and neck. Nitric oxide (NO) production may contribute to these processes. We assessed the role of the NO pathway in angiogenesis and tumor progression in patients with head and neck cancer.. Biochemical assays were used to measure NO synthase (NOS) activity and cyclic guanosine monophosphate (cGMP) levels in specimens of tumor and normal mucosa obtained from 27 patients. Microvessels in tumor specimens were identified by CD-31-specific immunohistochemical staining. Associations between microvessel densities, levels of NOS, and cGMP were examined by use of two-sided statistical tests. Tumor specimens and human squamous carcinoma A-431 cells were grown as explants on the corneas of rabbits, and the effect of the NOS inhibitor N(omega)-nitro-L-arginine-methyl ester (L-NAME) was tested.. Levels of total NOS, inducible NOS, and cGMP were higher in tumor specimens than in specimens of normal mucosa (all P<.0001). Tumor specimens from patients with lymph node metastases presented a higher total NOS activity (P = .005) and were markedly more vascularized than tumor specimens from patients with no lymph node involvement (P = .0002). Microvessel density at the tumor edge was an independent predictor of metastasis for this series of patients (odds ratio = 1.19; 95% confidence interval = 1.07-2.89; P = .04). A-431 cells and tumor specimens exhibiting high levels of NOS activity induced angiogenesis in the rabbit cornea assay; when NO production was blocked, tumor angiogenesis and growth were repressed.. The NO pathway appears to play a key role in tumor angiogenesis and spread in patients with head and neck cancer.

Topics: Adult; Aged; Carcinoma, Squamous Cell; Cyclic GMP; Disease Progression; Enzyme Inhibitors; Female; Fluorescent Antibody Technique; Head and Neck Neoplasms; Humans; Lymphatic Metastasis; Male; Middle Aged; Multivariate Analysis; Neoplasm Staging; Neovascularization, Pathologic; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Polymerase Chain Reaction; Transcription, Genetic; Tumor Cells, Cultured

To test the hypothesis that neural mechanisms evoked by unilateral pulmonary artery occlusion (UPAO) affect the release of atrial natriuretic peptides (ANP) from the heart, hemodynamics and levels of plasma ANP and cyclic guanosine monophosphate (c-GMP) were studied in 11 patients with lung cancer. The UPAO induced a significant rise in heart rate by 5.3 percent, increased mean pulmonary artery pressure by 31 percent without affecting right atrial pressure, and decreased plasma ANP levels in the coronary sinus by 17.4 percent (p < 0.05) from 202.5 +/- 27.1 pg/ml to 167.2 +/- 27.4 pg/ml. Atropine sulfate (0.04 mg/kg) injection increased the heart rate by 38.2 percent (p < 0.01), reduced the stroke volume index by 25.1 percent, decreased coronary sinus ANP levels from 198.5 +/- 16.4 pg/ml to 124.8 +/- 19.6 pg/ml (p < 0.01), and decreased coronary sinus plasma c-GMP levels from 4.6 +/- 0.5 pmol/ml to 3.1 +/- 0.4 pmol/ml (p < 0.05). After atropine pretreatment, UPAO induced a significant (p < 0.05) increase of 34.8 percent in the coronary sinus ANP level. Thus, it is concluded that in UPAO, the secretion of ANP from the heart is modulated partly by the autonomic nervous system.

Topics: Adenocarcinoma; Aged; Atrial Natriuretic Factor; Atropine; Carcinoma, Squamous Cell; Catheterization, Peripheral; Cyclic GMP; Female; Heart; Hemodynamics; Humans; Lung Neoplasms; Male; Middle Aged; Pulmonary Artery; Time Factors

Cytokines are produced by tumor cells in vitro, but evidence for in vivo increased production of cytokines in cancer patients is controversial. Conversely, nitric oxide (NO) is implicated increasingly in the mediation of cytokine effects. Lung cancer patients may show an increased local production of cytokines and NO, and chronic paracrine exposure of epithelial lung cells to these medicators may influence the production of surfactant phosphatidylcholine.. The presence of the cytokine tumor necrosis factor (TNF alpha), interleukin-1 (IL-1), and interleukin-6 (IL-6), as well as NO, cyclic guanosine 3'5' monophosphate (cGMP) and phosphatidylcholine levels in bronchoalveolar lavage fluid (BLF) of lung cancer patients were investigated. Bronchoalveolar lavage fluid was obtained from 30 male smokers: 22 patients with squamous cell lung cancer and 8 subjects without cancer.. When compared with the control subjects, the cancer patients had elevated BLF levels of TNF alpha (1.58 +/- 0.47 vs. 0.04 +/- 0.02 pg/microgram protein, P < 0.001), IL-6 (1.39 +/- 0.29 vs. 0.04 +/- 0.02 pg/microgram protein, P < 0.001), and NO2-/NO3- (23.3 +/- 5.6 vs 1.1 +/- 0.6 nmol/mg protein, P < 0.001). However, phosphatidylcholine levels were lower in those with cancer than in the control subjects (3.0 +/- 1.2 vs. 24.8 +/- 6.4 micrograms protein, P < 0.001).. The results showed in vivo production of inflammatory cytokines in human lung cancer and increased tumor-associated NO production, as suggested by increased levels of nitrite/nitrate in the BLF. A decreased phosphatidylcholine content in the BLF also was found in patients with lung cancer.

Topics: Bronchoalveolar Lavage Fluid; Carcinoma, Bronchogenic; Carcinoma, Squamous Cell; Cyclic GMP; Cytokines; Humans; Interleukin-1; Interleukin-6; Lung Diseases; Lung Neoplasms; Male; Middle Aged; Nitrates; Nitric Oxide; Nitrites; Phosphatidylcholines; Smoking; Tumor Necrosis Factor-alpha

In cell cultures treated with the carbocyclic analog of adenosine (C-Ado, (+/-)-aristeromycin), the utilization of hypoxanthine and guanine has been observed to be blocked. In an attempt to define the mechanism of this inhibition, we have reexamined the metabolism of C-Ado and its effects on the metabolism of guanine and hypoxanthine. In cultures of L1210 cells, C-Ado at a concentration of 25 microM inhibited the utilization of hypoxanthine and guanine for nucleotide synthesis by more than 90% but produced little or no inhibition of the utilization of these bases in cultures of L1210/MeMPR cells which lack adenosine kinase and cannot phosphorylate C-Ado. In cultures of mammalian cells (L1210, HEp-2, and colon-26 cells), C-Ado was converted to the triphosphate (as previously observed) and also to the triphosphate of the carbocyclic analog of guanosine. The presence of coformycin in the medium at a concentration sufficient to inhibit AMP deaminase almost completely prevented the formation of carbocyclic GTP; thus, the deamination of C-Ado monophosphate is essential for the formation of phosphates of carbocyclic guanosine. Since hypoxanthine (guanine) phosphoribosyltransferase is known to be subject to end product inhibition, it was considered likely that phosphates of carbocyclic guanosine or carbocyclic inosine, present in C-Ado-treated cells, were responsible for inhibition of utilization of hypoxanthine and guanine. The 5'-phosphates of the carbocyclic analogs of inosine and guanosine were synthesized and found to be effective inhibitors of the phosphoribosyltransferase. Carbocyclic GMP was a better inhibitor than carbocyclic IMP and was also superior to GMP and IMP; the concentration of C-GMP that produced a 50% inhibition of GMP formation was approximately 1 microM. It is probable that the presence of phosphates of carbocyclic guanosine accounts for the inhibition of utilization of hypoxanthine and guanine in C-Ado-treated cells.

Topics: Adenosine; Animals; Carcinoma, Squamous Cell; Cell Line; Coformycin; Colonic Neoplasms; Cyclic GMP; Cyclic IMP; Guanine; Humans; Hypoxanthine; Hypoxanthine Phosphoribosyltransferase; Hypoxanthines; Inosine Nucleotides; Kinetics; Leukemia L1210; Mice; Pentosyltransferases; Ribonucleotides

Epidermal growth factor (EGF) induces rapid rounding of A-431 human epidermoid carcinoma cells in Ca(++)-free medium. Cell rounding is not induced by a variety of other polypeptide hormones, antiserum to cell membranes, local anesthetics, colchicine, cytochalasin B, or cyclic nucleotides. However, trypsin, like EGF, induces rounding of A- 431 cells in the absence of Ca(++). Both trypsin- and EGF-induced rounding are temperature dependent, appear to be energy dependent, and are inhibited by cytochalasins, suggesting that the active participation of microfilaments in cell rounding. However, a medium transfer experiment suggests that EGF-induced rounding is not attributable to secretion of a protease, and a number of serine protease inhibitors have no effect on the EGF-induced rounding process. Cell rounding is not attributable to the slight stimulation by EGF of the release of Ca(++) that is observed in the Ca(++)-free medium, as stimulation of such release by the ionophore A23187 neither induces cell rounding nor blocks EGF-induced rounding. Cells that have rounded up after treatment with EGF or trypsin spread out upon addition of Ca(++) to the medium, even in the continuing presence of EGF or typsin. Like the cell-rounding process, the cell-spreading process is temperature dependent, appears to be energy dependent, and is inhibited by cytochalasin B. Thus, EGF does not destroy the ability of the cell to spread; rather, in the presence of the EGF (or trypsin), cell spreading and the maintenance of the flattened state become dependent on external Ca(++). Because untreated cells remain flattened in the absence of Ca(++), the data suggest that EGF may disrupt Ca(++)-independent mechanisms of adhesion normally present in A-431 cells.

Topics: Adenosine Triphosphate; Calcium; Carcinoma, Squamous Cell; Cell Line; Cells, Cultured; Cyclic AMP; Cyclic GMP; Cytoskeleton; Dose-Response Relationship, Drug; Epidermal Growth Factor; Humans; Microtubules; Peptides; Trypsin

Topics: Adenosine Triphosphate; Carcinoma, Squamous Cell; Cell Membrane; Cyclic AMP; Cyclic GMP; Electrophoresis; Epidermal Growth Factor; Humans; In Vitro Techniques; Membrane Proteins; Neoplasms, Experimental; Peptides; Phosphorylation

Adenosine and guanosine cyclic monophosphates (cAMP and cGMP) exerted opposite effects at similar concentration and similar effects at markedly different concentrations on the yields of tumors promoted by vitamin A in hamster cheek pouch. Increasing the concentration of cAMP between 10(-5) M and 10(-3) M was associated with increases in tumor yield and diameter which partially or completely overcame the net tumor promotion inhibitory effects which were sometimes seen at 10(-5) M cAMP. In contrast, increasing the concentration of cGMP between 10(-5) M and 10(-3) M caused the net effects to change from increases to decreases in tumor yield without much change in diameter. The relative magnitudes of the tumor yield increasing and decreasing effects of the cyclic nucleotides varied substantially between experiments at constant concentration of cyclic nucleotide. Adenosine-5'-monophosphate (AMP) showed simultaneous tumor promotion inhibitory and growth stimulatory effects, the former effect being similar to that of cAMP but tumor yield decreased rather than increased as concentration of AMP was increased whereas the opposite occured with cAMP. Guanosine-5'-monophosphate (GMP) showed the tumor yield increasing effect of low concentraitons of cGMP but not the yield decreasing effect of high concentrations of cGMP. Adenosine (10(-3) M) showed a significant tumor yield increasing effect similar to that of 10(-3) M cAMP. Guanosine showed no significant effects at either 10(-3) M or 10(-5) M concentrations.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Adenosine; Animals; Carcinoma, Squamous Cell; Cricetinae; Cyclic AMP; Cyclic GMP; Dimethyl Sulfoxide; Female; Guanosine; Mesocricetus; Mouth Neoplasms; Vitamin A

The activity of the phosphodiesterase enzyme(s) responsible for the degradation of cylic adenosine monophosphate (CA.M.P.) and cyclic guanosine monophosphate (CG.M.P. (in human normal and carcinomatous lung tissue has been investigated. Enzyme activities were 3-5 times greater in normal than in carcinomatous lung. This is compatible with the known higher concentrations of these cyclic nucleotides in normal tissues. It is suggested that cancer chemotherapy designed to block the phosphodiesterase activity, and thus promote accretion of CA.M.P and CG.M.P., may provide a means of normalising cancerous tissue. Both phosphodiesterase activities in both types of tissue were inhibited by methylxanthines at 10(-3) mol/l, but some enzyme potentiation was observed at lower concentration.

Topics: 2',3'-Cyclic-Nucleotide Phosphodiesterases; Caffeine; Carcinoma, Squamous Cell; Cyclic AMP; Cyclic GMP; Female; Humans; Lung; Lung Neoplasms; Middle Aged; Phosphoric Diester Hydrolases; Theophylline