Could somatostatin enhance the outcomes of chemotherapeutic treatment in SCLC?

Abstract

Purpose: Somatostatin is a peptide with a potent and broad antisecretory action, which makes it an invaluable drug target for the pharmacological management of pituitary adenomas and neuroendocrine tumors. Furthermore, somatostatin (SST) receptors (SSTR1, 2A and B, 3, 4 and 5) belong to the G protein coupled receptor family and are overexpressed in tumors. Since, human small-cell lung cancer overexpresses somatostatin receptors (STTR), they could be legitimate targets for treating SCLC. The aim of this study was the evaluation of cytotoxicity of somatostatin in combination with several anticancer drugs in HTB-175 cell line (Small Cell Lung Cancer Cell line that expresses neuron specific enolase). Methods: Docetaxel, Paclitaxel, Carboplatin, Cisplatin, Etoposide, Gemzar, Navelbine, Fluorouracil, Farmorubicin are the chemotherapeutic drugs that we used for the combination before and after adding somatostatin in SCLC cell culture. HTB-175 cell line was purchased from ATCC LGC Standards. At indicated time-point, 48h after the combination, cell viability and apoptosis were measured with Annexin V staining by flow cytometry. Results: Flow cytometry showed that Docetaxel, Paclitaxel, Gemzar and Cisplatin induced apoptosis more when they were added before somatostatin, whereas etoposide induced apoptosis more after somatostatin treatment. Navelbine alone or in combination with somatostatin showed no differences in apoptosis. Farmorubicin showed equal toxicity in all combinations. Fluorouracil and Carboplatin induced apoptosis more when added alone in HTB-175 cell line. However, increased apoptosis was also observed when Carboplatin was administered before somatostatin in higher concentrations. Conclusion: Our results indicated that depending on the drug, somatostatin treatment before or after chemotherapeutic drugs increased apoptosis in small cell lung cancer cells. We suggest that long acting somatostatin analogues could be used as additive and maintenance therapy in combination to antineoplastic agents in SCLC patients.