bombesin(6-14)--hca(6)-leu(13)-psi(ch2n)-tac(14)- and Lung-Neoplasms

New therapeutic strategies are necessary to improve the treatment of lung cancer. We investigated the effects of bombesin/gastrin-releasing peptide (GRP) antagonist, RC-3940-II, and growth hormone-releasing hormone (GHRH) antagonists, MZ-J-7-114 and MZ-J-7-118, on the expression of epidermal growth factor receptor (EGFR)/HER (-2, -3, and -4) family, angiogenic factors, VEGF-A and VEGF receptors (VEGF-R1 and VEGF-R2), and the apoptotic molecules Bax and Bcl-2, in H-460 and A-549 non-small cell lung carcinomas (NSCLC). Nude mice bearing xenografts of H-460 and A-549 NSCLC were treated daily with these peptide analogues for 4 weeks. The treatment resulted in growth inhibition of H-460 by 22-77% and A-549 NSCLCs by 64-84%. The inhibition of tumor growth was associated with a down-regulation of members of EGFR/HER family. A significant reduction of the levels of expression of EGFR/HER family on both tumors varied from 29-96%: the greatest inhibition being induced by RC-3940-II. Similarly, a significant decrease in the levels of VEGF-A in tumors by 19-60% and VEGF receptors (VEGF-R1, 24-74% and VEGF-R2, 25-50%) was detected after therapy. An up-regulation of Bax by 21-63% and a down-regulation of Bcl-2 by 23-39% was observed only for H-460 NSCLC. Our study demonstrates that human H-460 and A-549 NSCLC, express receptors for GHRH and bombesin/GRP, and respond to the respective antagonists. The antagonists of bombesin/GRP and GHRH could provide a new strategy for treatment of NSCLC through down-regulation of EGFR/HER family and an interference with the angiogenic and apoptotic pathways.

Topics: Animals; Apoptosis; bcl-2-Associated X Protein; Bombesin; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Down-Regulation; ErbB Receptors; Growth Hormone-Releasing Hormone; Humans; Lung Neoplasms; Mice; Neovascularization, Pathologic; Peptide Fragments; Proto-Oncogene Proteins c-bcl-2; Receptors, Bombesin; Sermorelin; Vascular Endothelial Growth Factor Receptor-1; Xenograft Model Antitumor Assays

Bombesin (BN) or gastrin-releasing peptide (GRP) can stimulate the growth of neoplasms such as breast cancer and small-cell lung carcinoma (SCLC). Antagonists of BN/GRP have been shown to inhibit these cancers. We evaluated whether antagonists of BN/GRP can suppress the growth of human non-SCLC (NSCLC) xenografted into nude mice. The effect of the administration of BN/GRP antagonist RC-3940-II on the growth of H460 and A549 NSCLC cell lines orthotopically xenografted into the intrapulmonary interstitium was examined. Protein levels of K-Ras, COX-2, Akt/pAkt, WT p53, Erk1/2, and lung resistance-related protein (LRP) in tumors were analyzed by Western blot analaysis, and receptors for BN/GRP were investigated by radioligand-binding studies. The effect of RC-3940-II on the proliferation of H460 and A549 cells in vitro was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays. High-affinity receptors for BN/GRP were found on tumors. Treatment with RC-3940-II significantly (P < 0.001) inhibited growth of H460 and A549 NSCLC xenografts by 30-50% and led to an improved performance status, compared with controls. In H460 NSCLC, the antitumor effect was associated with a significant (P < 0.001) reduction in protein levels of K-Ras, COX-2, pAkt, and pERK1/2 and with a major augmentation in the expression of WT p53, compared with controls. In A549 NSCLC, pAkt and LRP were significantly down-regulated. Our findings demonstrate the efficacy of BN/GRP antagonist RC-3940-II for the treatment of NSCLC. The suppression of K-Ras, COX-2, pAkt, and LRP, as well as the up-regulation of WT p53 might contribute to the antitumor action of BN/GRP antagonists.

Topics: Animals; Bombesin; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Cell Proliferation; Cyclooxygenase 2; Disease Progression; Gastrin-Releasing Peptide; Humans; Lung Neoplasms; Mice; Mice, Nude; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Peptide Fragments; Phosphorylation; Proto-Oncogene Proteins c-akt; ras Proteins; Receptors, Bombesin; Tumor Suppressor Protein p53; Xenograft Model Antitumor Assays

We investigated the effects of growth hormone-releasing hormone (GHRH) antagonists, JV-1-65 and JV-1-63, and bombesin/gastrin-releasing peptide (BN/GRP) antagonist RC-3940-II on DMS-153 human small cell lung carcinoma xenografted into nude mice. Treatment with 10 microg/day JV-1-65 or RC-3940-II decreased tumor volume by 28% (P < 0.05) and 77% (P < 0.01), respectively, after 42 days compared with controls. Combination of JV-1-65 and RC-3940-II induced the greatest inhibition of tumor proliferation (95%; P < 0.01), suggesting a synergism. Western blotting showed that the antitumor effects of these antagonists were associated with inhibition of the expression of the mutant tumor suppressor protein p53 (Tp53). Mutation was detected by sequence analysis of the p53 gene at codon 155: ACC [Thr] --> CCC [Pro]. Combination of JV-1-65 and RC-3940-II decreased the levels of mutant p53 protein by 42% (P < 0.01) compared with controls. JV-1-65, JV-1-63, and RC-3940-II, given singly, reduced mutant p53 protein expression by 18-24% (P < 0.05). Serum insulin-like growth factor (IGF)-I levels were diminished in animals receiving GHRH antagonists. mRNA levels for IGF-II, IGF receptor-I, GRP receptor, and EGF receptor in tumors were significantly decreased by combined treatment with JV-1-65 and RC-3940-II. DMS-153 tumors expressed mRNAs for GHRH and GHRH receptor splice variants 1 and 2, suggesting that GHRH could be an autocrine growth factor. Proliferation of DMS-153 cells in vitro was stimulated by GRP and IGF-II and inhibited by JV-1-65. This study indicates that GHRH antagonists and BN/GRP antagonist inhibit the growth of DMS-153 small cell lung carcinoma concomitantly with the expression of mutant Tp53, which might uncouple the signal transduction pathways for cell growth stimulation.

Topics: Amino Acid Substitution; Animals; Base Sequence; Bombesin; Carcinoma, Small Cell; Cell Division; DNA Primers; DNA, Complementary; Gene Expression Regulation, Neoplastic; Genes, p53; Growth Hormone-Releasing Hormone; Humans; Insulin-Like Growth Factor I; Lung Neoplasms; Mice; Mice, Nude; Molecular Sequence Data; Mutation, Missense; Peptide Fragments; Reverse Transcriptase Polymerase Chain Reaction; RNA, Neoplasm; Transplantation, Heterologous; Tumor Cells, Cultured

Antagonists of bombesin/gastrin-releasing peptide (BN/GRP) have been developed to block the autocrine stimulatory effect of BN/GRP on tumors such as small cell lung carcinoma (SCLC). Although several studies have addressed the intracellular events that follow the formation of the receptor-ligand complex, the mechanism of action of BN/GRP antagonists remains unclear.. In this study the authors investigated the effect of synthetic BN/GRP antagonists RC-3095 and RC-3940-II on tumor growth and the expression of epidermal growth factor receptors (EGF-R) in H-69 SCLC. Athymic nude mice xenografted with H-69 SCLC were treated subcutaneously for 5 weeks with RC-3095 and RC-3940-II at the dose of 10 microg/animal/day.. RC-3095 decreased tumor volume by approximately 50% (P < 0.05) and RC-3940-II by 70-60% (P < 0.01). Tumor burden also was significantly decreased in the groups treated with RC-3095 and RC-3940-II. Receptor analyses demonstrated high affinity binding sites for BN/GRP and EGF on the untreated H-69 SCLC tumors. After treatment with RC-3095 and RC-3940-II, the concentration of receptors for BN/GRP was decreased by 29.0% and 36.5%, respectively (both, P < 0.01) compared with controls, and EGF-R levels were reduced by 62.3% and 63.0%, respectively (both, P < 0.01). Reverse transcriptase-polymerase chain reaction and Southern blot analyses revealed that the levels of mRNA for EGF-R in tumors were lowered by 31% (P < 0.05) and 43% (P < 0.01), respectively, after treatment with RC-3095 and RC-3940-II.. This study indicates that the inhibition of growth of H-69 SCLC by BN/GRP antagonists RC-3095 and RC-3940-II is accompanied by a marked decrease in the levels and mRNA expression of EGF-R.

Topics: Animals; Anticarcinogenic Agents; Antigens, Neoplasm; Antineoplastic Agents; Blotting, Southern; Bombesin; Carcinoma, Small Cell; ErbB Receptors; Gastrin-Releasing Peptide; Lung Neoplasms; Male; Membrane Glycoproteins; Mice; Mice, Nude; Neoplasm Transplantation; Peptide Fragments; Polymerase Chain Reaction; RNA, Messenger; Transplantation, Heterologous; Tumor Cells, Cultured