bombesin(6-14)--hca(6)-leu(13)-psi(ch2n)-tac(14)- and Carcinoma--Non-Small-Cell-Lung

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