Two novel peptides derived from Sinonovacula constricta inhibit the proliferation and induce apoptosis of human prostate cancer cells

In China, the incidence of prostate cancer has been increasing. Toxicity, drug resistance and limited transient benefits in patients are the main problems associated with standard chemotherapeutic regimens, and new drugs are therefore required to treat prostate cancer. SCH-P9 and SCH-P10 proteins were obtained from Sinonovacula constricta hydrolysates. The amino acid sequences of SCH-P9 and SCH-P10 were identified as Leu-Pro-Gly-Pro and Asp-Tyr-Val-Pro, with molecular weights of 382.46 Da and 492.53 Da, respectively. An MTT assay, annexin V-fluorescein isothiocyanate (FITC) staining and cell cycle analysis were applied to identify the viability of cells, stages of apoptosis, and cell cycle distribution, respectively. SCH-P9 and SCH-P10 inhibited the growth of DU-145 and PC-3 cells in a dose- and time-dependent manner. Annexin V-FITC staining and flow cytometry analysis were employed to measure apoptosis and cell cycle arrest, respectively. SCH-P9 and SCH-P10 inhibited the growth of DU-145 cells by reducing the number of cells in G(0)/G(1) phase, increasing the number in subG(1) phase and inducing apoptosis. SCH-P9 reduced the number of PC-3 cells in subG(1) and G(0)/G(1) phases, increased the number of cells in G(2)/M phase and induced apoptosis. SCH-P10 reduced the number of PC-3 cells in G(2)/M phase, increased the number of cells in G(0)/G(1) phase and induced apoptosis. In conclusion, the results demonstrated that SCH-P9 and SCH-P10 induced apoptosis in DU-145 and PC-3 cells and may, therefore, exhibit potential for application in the treatment of prostate cancer.