guanosine-5--o-(3-thiotriphosphate) and Adenocarcinoma

Vessel dilator and kaliuretic peptide have anticancer effects in human prostate adenocarcinomas.. The effects of vessel dilator, kaliuretic peptide and cyclic GMP on Ras were examined in human prostate adenocarcinoma cells.. Vessel dilator and kaliuretic peptide decreased the activation of Ras -GTP over a concentration range of 0.01 microM to 1 microM. Vessel dilator and kaliuretic peptide (each 1 muM) inhibited the phosphorylation of Ras by 95% (p<0.0001) and 90% (p<0.0001), respectively. At 0.01 microM of kaliuretic peptide, the maximal inhibition was 95% . The inhibition of Ras lasted for 48 to 72 hours secondary to both peptides. Their ability to inhibit Ras was inhibited by cyclic GMP antibody and cyclic GMP itself inhibited Ras phosphorylation (89%; p=0.0015).. Vessel dilator and kaliuretic peptide both inhibit Ras partially mediated via cyclic GMP as part of their anticancer mechanism(s) of action.

Topics: Adenocarcinoma; Aged; Atrial Natriuretic Factor; Cyclic GMP; Guanosine 5'-O-(3-Thiotriphosphate); Guanosine Diphosphate; Humans; Immunoblotting; Male; Natriuresis; Peptide Fragments; Prostatic Neoplasms; Protein Precursors; ras Proteins; Sodium-Potassium-Exchanging ATPase; Tumor Cells, Cultured

The two major forms of lung carcinoma, small cell lung carcinoma (SCLC) and non-small cell lung carcinoma (NSCLC), are clinically distinct, and are also differentiated by morphology and behavior in culture. SCLC cells have a greater metastatic potential than NSCLC cells in vivo, and exhibit a unique spherical morphology in culture due to their inability to adhere and spread on the substratum. Because the small GTPase RhoA affects metastatic properties and regulates cell morphology, we examined whether differences in RhoA expression and activity contribute to the distinct SCLC and NSCLC phenotypes. We found that the expression and GTPgammaS-dependent activation of RhoA are generally greater in SCLC cell lines (SCC-9, NCI-H69, NCI-H146, and NCI-H345) than in NSCLC cell lines (NCI-H23, NCI-H157, NCI-H520, and NCI-H522). The effects of inhibiting Rho-mediated signaling in these cells were investigated by transfecting the cells with cDNA coding for C3 exoenzyme, which ADP-ribosylates and inactivates Rho. Expression of C3 exoenzyme in SCLC cells induces cell-cell compaction, and causes NCI-H345 cells to adhere and spread on collagen IV. In contrast, expression of C3 exoenzyme in NSCLC cells does not induce detectable compaction, but induces cell spreading of NCI-H23 and NCI-H157 cells. Cell proliferation is diminished by Rho inactivation in the majority of the NSCLC cell lines, but not the SCLC cell lines. Expression of p21Cip1/WAF1 is also diminished by Rho inactivation in two of the SCLC cell lines, but is not significantly altered in the NSCLC lines. These results indicate that Rho-mediated signaling may regulate different events in SCLC and NSCLC cells, including adhesion of SCLC cells and proliferation of NSCLC cells.

Topics: Adenocarcinoma; Adenosine Diphosphate Ribose; ADP Ribose Transferases; Botulinum Toxins; Carcinoma, Non-Small-Cell Lung; Carcinoma, Small Cell; Carcinoma, Squamous Cell; Cell Adhesion; Cell Division; Cell Size; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; DNA, Complementary; Gene Expression Regulation, Neoplastic; Guanosine 5'-O-(3-Thiotriphosphate); Humans; Lung Neoplasms; Neoplasm Metastasis; Neoplasm Proteins; rhoA GTP-Binding Protein; Signal Transduction

The anti-proliferative activity of the somatostatin analog RC-160 is limited by its short serum half life. To circumvent this limitation, fatty acids of chain lengths ranging from 4 to 18 were individually conjugated to the N-terminal residue of RC-160. The lipophilized derivatives of RC-160 were synthesized, purified and characterized. The anti-proliferative activity of lipophilized-RC-160 on the human breast carcinoma cell line MCF-7, was evaluated in vitro. The long chain lipopeptides like pamitoyl-RC-160 exhibited significantly higher anti-proliferative activity on MCF-7 cells (p<0.001), relative to RC-160. The affinity of RC-160 towards somatostatin receptors remained unaltered by pamitoylation. However, the observed increase in bioactivity was manifested within an optimum range of chain length of the lipoppetide. Increasing the peptide hydrophobicity beyond this range reduced the bioactivity of lipophilized-RC-160. Accordingly, stearoyl-RC-160, manifested lower anti-neoplastic activity and receptor affinity relative to pamitoyl-RC-160 and RC-160 itself. The signaling pathways underlying the antineoplastic activity of these lipopeptides were found to be similar to RC-160. Pamitoyl-RC-160 displayed enhanced inhibition of protein tyrosine kinase activity and intracellular cAMP levels in MCF-7 cells, relative to butanoyl-RC-160 or RC-160 itself. Pamitoyl-RC-160 also displayed greater resistance towards trypsin and serum degradation than RC-160. Lipophilization of RC-160 with long chain fatty acids like pamitic acid improves its stability and anti-proliferative activity, thereby improving the scope of enhancing its therapeutic index. However, the optimization of peptide hydrophobicity seems to be a crucial factor governing the efficacy of bioactive lipopeptides.

Topics: Acylation; Adenocarcinoma; Antineoplastic Agents, Hormonal; Binding, Competitive; Breast Neoplasms; Cell Division; Cyclic AMP; Endopeptidases; Enzyme Inhibitors; Fatty Acids; Female; Freeze Drying; Guanosine 5'-O-(3-Thiotriphosphate); Half-Life; Hormone Antagonists; Humans; Protein-Tyrosine Kinases; Signal Transduction; Somatostatin; Structure-Activity Relationship; Tumor Cells, Cultured

Previous study shows volume-sensitive chloride currents are induced by hypotonicity in human cervical cancer cell lines, but not in normal cervical epithelium. To ascertain whether the preferential activation of these channels in cancer cell lines could be similarly and directly detected in cervical cancer tissues, we studied volume-sensitive chloride channels on the primary culture cells of invasive cervical carcinoma using the whole-cell patch-clamp technique. The process of regulatory volume decrease (RVD) was also studied using electronic cell sizing to measure cell volume. Results demonstrate that, in these cultured cells, RVD was mediated in part by chloride loss through the volume-sensitive Cl- channels. A small background current with a slope conductance of 0.32 +/- 0.07 nS/pF at +30 mV (n=60 cells from 10 different samples) was observed. Hypotonicity induced a fast activating and outward rectifying current which was reversed at about 0 mV, and the slope conductance at +30 mV was increased by 10-fold to 3.62 +/- 0.62 nS/pF. These effects were readily reversed by returning the cells to isotonic medium. Moreover, DIDS, NPPB, and 1,9-dideoxyforskolin, reversibly abolished the volume-sensitive Cl- currents. The EC50 required for the inhibitory effect of DIDS, NPPB and 1,9-dideoxyforskolin was 150, 120, and 50 microM, respectively. Volume-sensitive Cl- channels were ubiquitously expressed in cultured cells from 10 samples of different cancer stages, histopathologic types, and state of HPV DNA positivity. Interestingly, similar outward rectifying chloride currents were activated by intracellular 300 microM GTP gamma S. It is proposed that this Cl- conductance may play an important role leading to RVD in human cervical cancer.

Topics: 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; Adenocarcinoma; Base Sequence; Carcinoma, Squamous Cell; Cell Membrane; Cesium; Chloride Channels; Chlorides; DNA Primers; DNA, Viral; Female; Genome, Viral; Guanosine 5'-O-(3-Thiotriphosphate); Humans; Kinetics; Membrane Potentials; Molecular Sequence Data; Neoplasm Staging; Papillomaviridae; Patch-Clamp Techniques; Polymerase Chain Reaction; Tumor Cells, Cultured; Uterine Cervical Neoplasms

This study examined the expression of receptors of the bombesin (BBS) family in human gastric-cancer cell lines. Of 5 cell lines screened, only one, St42, demonstrated specific binding sites for 125I-Tyr4-BBS, which have been further characterized. This binding was saturable, and temperature- and time-dependent. Scatchard analysis of displacement data performed at 37 degrees C revealed 2 binding sites: a high-affinity, low-capacity site (KD = 0.13 nM, Bmax = 1500 sites/cell) and a lower-affinity, higher-capacity site (KD = 11 nM, Bmax = 35,000 sites/cell); the latter was lost when internalization of peptide was prevented, suggesting that it may be an artefact. Displacement assays with gastrin-releasing peptide (GRP) and neuromedin B (NMB) revealed that the receptor was of the GRP-preferring sub-type (GRP IC50 = 0.35 nM; NMB IC50 = 112 nM). Co-valent cross-linking of 125I-Tyr4-BBS to the receptor demonstrated the presence of a single band corresponding to a molecular weight of 37 to 44 kDa on SDS-PAGE, similar to that of the cloned GRP receptor protein core. G-protein linkage of this receptor was demonstrated by selective inhibition of 125I-Tyr4-BBS binding by guanosine nucleotides. The binding of BBS to the receptor resulted in a rise in intracellular calcium. Three of four structurally distinct BBS antagonists bound to the receptor with high affinity, but [DPhe12, Leu14]-bombesin did not cause any displacement of 125I-Tyr4-BBS even at 10 mM. The functional significance of GRP receptors on human gastric-cancer cells is as yet unknown, but further studies may determine whether such receptors have importance in the therapy of gastric cancer.

Topics: Adenocarcinoma; Binding, Competitive; Calcium; Cell Membrane; Endocytosis; Guanosine 5'-O-(3-Thiotriphosphate); Humans; In Vitro Techniques; Molecular Weight; Receptors, Bombesin; Second Messenger Systems; Signal Transduction; Stomach Neoplasms; Tumor Cells, Cultured