Activation of PKR/eIF2a signaling cascade is associated with dihydrotestosterone-induced cell cycle arrest and apoptosis in human liver cells

Androgen receptor (AR) signaling plays an important role in the development and progression of several liver diseases, including hepatocellular carcinoma (HCC) and non-alcoholic fatty liver disease (NAFLD). Dihydrotestosterone (DHT) is the active metabolite of the major circulating androgen, testosterone. In this study, we investigated the effect of DHT on human liver cells. We found that DHT not only induces cell cycle arrest but also initiates apoptosis in androgen-sensitive liver cells, such as SMMC-7721 and L02. Importantly, DHT/AR induces the activation of RNA-dependent protein kinase (PKR)/eukaryotic initiation factor-2 alpha (eIF2a) cascades in androgen-sensitive liver cells. PKR/eIF2a activation-induced growth arrest and DNA damage-inducible gene 153 (GADD153) and heat shock protein 27 (Hsp27) expression contribute to cell cycle arrest in response to DHT. It is notable that DHT administration results in androgen-sensitive liver cells apoptosis, at least in part, through PKR/eIF2a/GADD153 cascades. These results suggest that the androgen/AR pathway plays a pivotal role in liver cell growth and apoptosis regulating, whose deregulation might be involved in the pathogenesis of liver diseases. J. Cell. Biochem. 113: 18001808, 2012. (C) 2012 Wiley Periodicals, Inc.