The cellular uptake of Cordyceps sinensis exopolysaccharide‑selenium nanoparticles and their induced apoptosis of HepG2 cells via mitochondria- and death receptor-mediated pathways

Abstract

This wok investigated the effects of Cordyceps sinensis exopolysaccharide‑selenium nanoparticles (EPS-SeNPs), EPS-Se-1, EPS-Se-2, EPS-Se-3, and EPS-Se-4) with particle sizes (79–124 nm) and Se contents (20.11–40.80 μg/mg) on endocytosis and antitumor activity against human hepatocellular carcinoma (HepG2) cells and revealed the apoptosis-related mechanisms. EPS-SeNPs inhibited HepG2 cells proliferation in a dose and Se content-dependent manner by disrupting cell membrane and mitochondrial integrity, promoting reactive oxygen species production. EPS-SeNPs were endocytosed by HepG2 cells through a clathrin-mediated pathway and followed the quasi-first-order kinetics model, indicating physical adsorption played a dominant role in cellular uptake behavior of EPS-SeNPs. Notably, EPS-Se-3 with the lowest particle size (79 nm) showed the highest antitumor activity and the strongest ability to promote cell apoptosis. Western blotting results revealed that EPS-Se-3 increased expressions of Bax, Cytochrome c, cleaved caspase-9, cleaved caspase-3, Fas, p53, and cleaved caspase-8, while decreased the expressions of Bcl-2 and PARP, as contrast to that of control. Overall, EPS-SeNPs induced cell apoptosis through intrinsic mitochondria-mediated and extrinsic death receptor-mediated pathways.