Gambogenic acid inhibits the proliferation of small-cell lung cancer cells by arresting the cell cycle and inducing apoptosis

Gambogenic acid (GNA), which is an important active compound present in gamboge, exerts anticancer activity in various types of tumor cells. However, the effect of GNA on small-cell lung cancer (SCLC) cell lines and the underlying mechanism involved still remain unclear. In the present study, GNA inhibited the proliferation and cell cycle progression of SCLC cells. GNA also promoted the apoptosis of SCLC cells in a dose-dependent manner, which is associated with modulating the levels of proteins involved in apoptosis pathways in NCI-H446 and NCI-H1688 cells. The results demonstrated that GNA increased the level of cleaved caspase-3, -8 and -9, and Bax but decreased the expression of anti-apoptotic protein, Bcl-2. Furthermore, similar results were obtained in a mouse tumor xenograft model. Additionally, GNA exhibit low toxicity in tissues when administered to mice in the SCLC xenograft models. Collectively, our findings demonstrated that GNA significantly inhibited the proliferation of SCLC cells and promoted cell apoptosis via cell cycle arrest and induction of apoptosis.