Amentoflavone Promotes Apoptosis in Non-Small-Cell Lung Cancer by Modulating Cancerous Inhibitor of PP2A.

Non-small-cell lung cancer (NSCLC) is one of the most common human malignancies. Amentoflavone (AF) is one of bioflavonoid compounds isolated from Selaginella tamariscina Spring. This study was designed to examine the effect of AF on NSCLC. Our results indicated that AF decreased cell viability of both H1299 and H358 cells. Colony formation assay also showed that AF was able to suppress the anchorage-independent growth of NSCLC cells. AF also triggered cell cycle arrest by downregulating cyclin D1, CDK4, and CDK6. The pro-apoptotic activity of AF was confirmed by Hoechst staining and flow cytometry. The effect of AF on activation of caspase-3, upregulation of Bax, and downregulation of Bcl-2 was examined by western blot. The anti-growth and pro-apoptotic activities of AF were further validated in xenograft murine model. iTRAQ assay showed that cancerous inhibitor of PP2A (CIP2A) expression was markedly downregulated by AF treatment in H1299 cells. In addition, qRT-PCR and western blot also showed that AF was able to dose-dependently inhibit CIP2A expression. Meanwhile, the activity of protein phosphatase 2A (PP2A) was enhanced by AF treatment. The mRNA and protein expression of CIP2A as well as PP2A activity in xenograft tumor tissue were examined, which indicated that the in vivo anticancer activity of AF was associated with downregulation of CIP2A and reactivation of PP2A. Moreover, our results showed that the anti-growth and pro-apoptotic activities of AF were augmented by CIP2A knockdown and attenuated by ectopic CIP2A expression. Our results indicated that AF exhibited anticancer activity in NSCLC by targeting CIP2A. Anat Rec, 302:2201-2210, 2019.