Epigallocatechin‐3‐gallate sensitizes therapeutic efficacy of doxorubicin involving autophagy inhibition in hepatoma Hep3B cells (655.2)

Abstract

The green tea component (‐)‐Epigallocatechin‐3‐O‐gallate(EGCG), has promisingly been found to enhance the efficacy of several chemotherapy agents in hepatocellular carcinoma (HCC) treatment and its detailed mechanisms remain unclear. Herein, this study aimed to confirm the synergistic interaction of EGCG and DOX on Hep3B cells and to define whether the autophagic flux is involved in this cooperated fashion. Firstly, by MTT and trypan blue assay, both EGCG and DOX exhibited cellular growth inhibition and cell death induction effects. However, by western blotting and real time RT‐PCR, DOX dramatically induced the expression of Atg5 and beclin1, the autophagic signaling molecules, whereas EGCG presented a markedly and dose‐dependently inhibitory role in autophagy signaling. Secondly, EGCG and DOX combined treatment amazingly caused a synergistic effect of about 50% increment on cell death and about 45% augmentation on apoptosis versus monotherapy pattern. Interestingly, the DOX‐induced autophagy was abolished by this combination therapy. Thirdly, the anticancer effect of either DOX or combination with EGCG treatment was substantially impaired by either rapamycin, an autophagic agonist, or Atg5 as well as beclin1 siRNAs. Consistently, significantly tumor growth reduction and apoptosis increment were found in combination therapy compared with DOX alone in vitro study. And immunohistochemisty analysis indicated that the suppressed tendency of autophagic hallmark LC3 expression was consistent with thus combined usage in vitro. Taken together, the current study suggested that EGCG emerges as a chemotherapeutic augmenter and synergistically enhances DOX anticancer effects involving autophagy inhibition in HCC.Grant Funding Source: Supported by NSFC Grants 881172260, 30630145, 81360077 to G.Z. & 81102495 to L.C.