Curcumin suppresses the proliferation of gastric cancer cells by downregulating H19

Abstract

Curcumin, a major phytochemical in turmeric, inhibits the proliferation of many types of solid cancer cells by enhancing p53 expression. However, the long non–coding RNA H19 directly inhibits p53 activation and thus promotes gastric cancer progression. The aim of this study was to assess the role of H19 in curcumin–induced proliferative inhibition of gastric cancer. The gastric cancer cell line SGC–7901 was treated with curcumin at different concentrations and time points. The effect of curcumin on proliferation was assessed using cell counting kit–8 assays and flow cytometry with Ki67 staining. In addition, H19 expression was quantified by reverse transcription–quantitative polymerase chain reaction, and apoptosis was evaluated by flow cytometric detection of Annexin V and propidium iodide double staining. The protein expression of p53, B–cell lymphoma (Bcl)–2, Bcl–2–associated X protein (Bax) and c–Myc in curcumin–treated cells was detected by western blotting. The present study demonstrated that curcumin inhibited the proliferation of SGC7901 cells and suppressed H19 expression in a concentration–dependent manner, while p53 expression was enhanced. Ectopic expression of H19 in SGC7901 cells reversed curcumin–induced proliferative inhibition and downregulated p53 expression. Furthermore, while curcumin induced cell apoptosis and enhanced the expression ratio of Bax/Bcl–2, which are downstream molecules of p53, ectopic expression of H19 inhibited curcumin–induced cell apoptosis. In addition, curcumin decreased the expression of the c–Myc oncogene, and exogenous c–Myc protein reversed the curcumin–induced downregulation of H19 expression. These results suggested that curcumin inhibits the proliferation of gastric cancer cells by downregulating the c–Myc/H19 pathway. Therefore, curcumin may be considered a novel therapeutic strategy to inhibit gastric cancer cell growth.