Diarylheptanoid-myricanone isolated from ethanolic extract of Myrica cerifera shows anticancer effects on HeLa and PC3 cell lines:signalling pathway and drug-DNA interaction

OBJECTIVE:To test if myricanone(C21H24O5),a cyclic diarylheptanoid,has anticancer effects on two different cancer cell lines HeLa and PC3.The present study was conducted with a note on the drug-DNA interaction and apoptotic signalling pathway.METHODS:Several studies like cytotoxicity,nuclear damage,annexin-V-fluorescein isothiocyanate（FITC）/propidium iodide（Pl）-labelled apoptotic assay and cell cycle arrest,immunoblot and reverse transcriptase-polymerase chain reaction（RT-PCR）were used following standard protocols.Circular dichroism（CD）spectroscopy was also done to evaluate whether myricanone effectively interacted with DNA to bring about conformational changes that could strongly inhibit the cancer cell proliferation.RESULTS:Myricanone showed a greater cytotoxic effect on PC3 cells than on HeLa cells.Myricanone promoted G0/G1 arrest in HeLa cells and S phase arrest in PC3 cells.Nuclear condensation and annexin V-FITC/PI studies revealed that myricanone promoted apoptotic cell death.CD spectroscopic data indicated that myricanone had an interaction with calf thymus DNA that changed DNA structural conformation.RT-PCR and immunoblot studies revealed that myricanone activated the apoptotic signalling cascades through down-regulation of transcription factors like nuclear factor-κB（NF-κB）(p65),and signal transducers and activators of transcription 3（STAT3）;cell cycle regulators like cyclin D1,and survivin and other signal proteins like Bcl-2 and up-regulation of Bax,caspase-9 and caspase-3.CONCLUSION:Myricanone induced apoptosis in both types of cancer cells by triggering caspase activation,and suppression of cell proliferation by down-regulation of NF-κB and STAT3signalling cascades,which makes it a suitable candidate for possible use in the formulation of therapeutic agent for combating cancer.