Hesperetin regulates PI3K/Akt and mTOR pathways to exhibit its antiproliferative effect against colon cancer cells.

Abstract

Hesperetin, a citrus flavonoid, has been a widely studied anticancer agent against many types of cancers, but the exact mechanism of efficacy is still unrevealed. Therefore, this study has attempted to delineate the mechanical aspect of hesperetin's anticancer efficacy against colon cancer using immunoblotting, scanning, and transmission electron microscopic studies. The treatment with hesperetin (25 and 50 µM) has significantly (p < 0.0001) curbed down the proliferation and cell viability of HCT-15 cells in a concentration as well as time dependent manner. Hesperetin was able to achieve this through the induction of caspase-dependent apoptosis. Moreover, hesperetin effectively inhibited phosphorylation of Akt with a parallel increase in PTEN expression thereby inhibiting the PI3K signaling axis, which contributes to the suppression of proliferation. In addition, hesperetin enhanced autophagy through dephosphorylating mTOR, one of the downstream targets of Akt with simultaneous acceleration in Beclin-1 and LC3-II expression levels. Interestingly, hesperetin enhanced the effects of Akt inhibitor LY294002 and mTOR inhibitor rapamycin. This study documented the potential of hesperetin to induce apoptosis through simultaneous acceleration over the autophagic process in colon cancer cells. Thus, hesperetin played a beneficial therapeutic role in preventing colon carcinoma growth by regulating the Akt and mTOR signaling axis.