MicroRNA216b mediated downregulation of HSP27/STAT3/AKT signaling is critically involved in lambertianic acid induced apoptosis in human cervical cancers.

Since heat shock protein (HSP27) is a prognostic marker in cervical cancer, in the present study, the apoptotic mechanism of lambertianic acid (LA) was investigated in human cervical cancers in association with HSP27/STAT3/AKT signaling axis. LA exerted significant cytotoxicity, induced sub-G1 population, and increased the cleavage of Poly (ADP-ribose) polymerase (PARP) and cysteine aspartyl-specific protease 3 (caspase3) in HeLa and Caski cancer cells. Consistently, LA downregulated anti-apopotic genes such as B-cell lymphoma 2 (Bcl-2) and inhibitors of apoptosis proteins (c-IAP) in HeLa and Caski cells. Furthermore, LA-inhibited phosphorylation of HSP27, signal transducer, and activator of transcription 3 (STAT3) and Protein kinase B (AKT) through disturbing the binding of HSP27 with STAT3 or AKT in HeLa cells. Notably, LA upregulated the level of miR216b in HeLa and Caski cells. Consistently, miR216b mimic suppressed phosphorylation of HSP27 and reduced the expression of pro-PARP, while miR216b inhibitor reversed the ability of LA to attenuate phosphorylation of AKT, HSP27, and STAT3 and to reduce the expression of pro-PARP in HeLa cells. Overall, our findings suggest that miRNA216b mediated inhibition of HSP27/STAT3/ AKT signaling axis is critically involved in LA-induced apoptosis in cervical cancers.