Activation of the PI3K-AKT-mTOR signaling pathway promotes DEHP-induced Hep3B cell proliferation

Abstract

Hep3B cells were treated with DEHP at various concentrations (62.5, 125.0, 250.0, 500.0 and 1000.0 μM). After 24 h exposure to DEHP only, increased Hep3B cell viability was observed (p<0.05 or p<0.01). However, after 24 h co-exposure to DEHP at indicated concentrations plus 50.0 μM LY294002 (PI3K inhibitor), cell viability was significantly decreased compared to the corresponding DEHP treated groups. DEHP increased mitochondrial membrane potential level and induced oxidative DNA damage in Hep3B cells, DEHP also increased DNA replication rate and accelerated the cell cycle. The PI3K inhibitor LY294002 could recover the mitochondrial membrane potential and attenuate the oxidative stress in Hep3B cells; however, it could not protect the cells from oxidation of DNA damage. The findings showed that LY294002 attenuated DEHP-induced up-regulation of the selected genes (pi3k, akt, mtor and p70s6k) involved in PI3K-AKT-mTOR signaling pathway at both mRNA and protein levels thus inhibited the cell abnormal proliferation.

Keywords: 40S ribosomal protein S6 kinase; 8-OHdG; 8-hydroxy-2′-deoxyguanosine; AKT; DEHP; DMSO; Di-(2-ethylbexyl) phthalate; GSH; GSSG; Oxidative stress; PI3K; PI3K–AKT–mTOR pathway; PPAR; Proliferation; ROS; TBST; buffered saline with tween 20; di-(2-ethylhexyl) phthalate; dimethyl sulfoxide; glutathione; mTOR; mammalian target of rapamycin; oxidized glutathione; p70S6K; peroxisome proliferators-activated receptor; phosphoinositide 3-kinase; protein kinase B; reactive oxygen species.