Smh-3 induces G2/M arrest and apoptosis through calcium-mediated endoplasmic reticulum stress and mitochondrial signaling in human hepatocellular carcinoma Hep3B cells

Abstract

In the present study, we investigated the antitumor effects of Smh-3 on the viability, cell cycle and apoptotic cell death in human hepatocellular carcinoma Hep3B cells in vitro. We also investigated the molecular mechanisms involved in the effects of Smh-3 on human hepatoma Hep3B cells, including the effects on protein and mRNA levels which were determined by western blotting and DNA microarray methods, respectively. The results demonstrated that Smh-3 induced growth inhibition, cell morphological changes and induction of G(2)/M arrest and apoptosis in Hep3B cells. DNA microarray assay identified numerous differentially expressed genes related to angiogenesis, autophagy, calcium-mediated ER stress signaling, cell adhesion, cell cycle and mitosis, cell migration, cytoskeleton organization, DNA damage and repair, mitochondrial-mediated apoptosis and cell signaling pathways. Furthermore, Smh-3 inhibited CDK1 activity, mitochondrial membrane potential (ΔΨm) and increased the cytosolic Ca(2+) release and caspase-4, caspase-9 and caspase-3 activities in Hep3B cells. Western blot analysis demonstrated that Smh-3 increased the protein levels of caspase-4 and GADD153 that may lead to ER stress and consequently apoptosis in Hep3B cells. Taken together, Smh-3 acts against human hepatocellular carcinoma Hep3B cells in vitro through G(2)/M phase arrest and induction of calcium-mediated ER stress and mitochondrial-dependent apoptotic signaling pathways.