Lentinan inhibited colon cancer growth by inducing endoplasmic reticulum stress-mediated autophagic cell death and apoptosis

Lentinan (SLNT) has been shown to be directly cytotoxic to cancer cells. However, this direct antitumour effect has not been thoroughly investigated in vivo, and the mechanism remains unclear. We aimed to examine the direct antitumour effect of SLNT on human colon cancer and the mechanism in vivo and in vitro. SLNT significantly inhibited tumour growth and induced autophagy and endoplasmic reticulum stress (ERS) in HT-29 cells and tumour-bearing nonobese diabetic (NOD)/severe combined immunodeficiency (SCID) mice. Experiments with the autophagy inhibitors chloroquine (CQ) and 3-methyladenine (3-MA) showed that autophagy facilitated the antitumour effect of SLNT. Moreover, ERS was identified as the common upstream regulator of SLNT-induced increases in Ca2+concentrations, autophagy and apoptosis by using ERS inhibitors. In summary, our study demonstrated that SLNT exerted direct antitumour effects on human colon cancer via ERS-mediated autophagy and apoptosis, providing a novel understanding of SLNT as an anti-colon cancer therapy.