Long noncoding RNA GAS5 modulates α-Solanine-induced radiosensitivity by negatively regulating miR-18a in human prostate cancer cells

Radiotherapy is an adjuvant treatment of surgery in prostate cancer, while radioresistance has been the challenge of treatment. It has been reported that alpha-Solanine exhibits anti-cancer activity and enhances the chemoand radio-sensitivity in several human cancers, whereas the role of alpha-Solanine on radiosensitivity to PCa remains to be uncovered yet. We found alpha-Solanine decreased cell viability in human PCa cells rather than normal prostate epithelial cells in vitro. Functional experiments showed that cell viability and colonies formation were declined & apoptosis rate and DNA double strand breaks (DSBs) marker gamma-H2AX expressions were elevated by alpha-Solanine in PCa cells treated with X-ray irradiation, compared with X-ray irradiation treatment only. GAS5 was down-regulated & miR-18a was up-regulated in PCa cells, which was reversed in the presence of alpha-Solanine. Effects of ectopic GAS5 on inhibiting cell viability and survival & promoting apoptosis and DNA damage were reversed by miR-18a overexpression in PCa cells. Moreover, GAS5 regulated miR-18a expression by target binding during alpha-Solanine treatment. Collectively, alpha-Solanine suppresses cell proliferation and promotes radiosensitivity through up-regulating GAS5/ miR-18a pathway in PCa. Our results provide a novel mechanism of alpha-Solanine treatment in human prostate cancer and help to develop a new approach to sensitizing radioresistant prostate cancer cells by targeting GAS5/ miR-18a.