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This study has been undertaken to explore the therapeutic effects of deguelin and specific siRNAs in HeLa cells. The data provided clearly show the silencing of ERK 1/2 with siRNAs and inhibition of ERK1/2 with deguelin treatment in HeLa cells. Additionally, we are providing information that deguelin binds directly to anti-apoptotic Bcl-2, Bcl-xl and Mcl-1 in the hydrophobic grooves, thereby releasing BAD and BAX from dimerization with these proteins. This results in increased apoptotic activity through the intrinsic pathway involved in rupture of mitochondrial membrane and release of cytochrome C. Evidence for inhibition of ERK1/2 by deguelin and escape of BAD phosphorylation at serine 112 through ERK/RSK pathway has been further fortified by obtaining similar results by silencing ERK 1/2 each with specific siRNAs. Increase in BAD after treatment with deguelin or siRNAs has been interpreted to mean that deguelin acts through several alternative pathways and therefore can be used as effective therapeutic agent.

Overexpression of Bcl-2 has been recognized in various malignancies. Recently, HA14-1, a Bcl-2 antagonist, has been identified for its anti-apoptotic effect. However, mode of action of HA14-1 still remains to be elucidated. In this study, we examined HA14-1 binding efficiency with receptor proteins through molecular docking. Cell viability using HeLa cells was evaluated through MTT assay after exposure to different concentration of HA14-1. Moreover, after HA14-1 exposure, expressions of tumor suppressor protein (p53), BH3-only protein (Puma) and apoptosis-associated proteins were analyzed by Western blotting. From the results, it was found that HA14-1 occupied all three domains; BH1, BH2, and BH3 within the hydrophobic pocket of Bcl-2. However, HA14-1 occupied only BH1 and BH3 of Bcl-xl, conversely, no such stable bond was observed for Bax and Bak. ARG107 and TYR101 were the amino acids involved in the binding of HA14-1 to Bcl-2 and Bcl-xl, respectively. Additionally, decrease in Bcl-2 and Bcl-xl expression along with increase in p53 and Puma expression after exposure to HA14-1 was observed. The results suggested p53 pathway to be the probable mechanism of action for the induction of apoptosis in HeLa cell by downregulating the effect of anti-apoptotic proteins suggesting that HA14-1 may provide therapeutic potential for the treatment of human cervical cancer., (© 2013 John Wiley & Sons A/S.)