These Poziotinib supplier observations suggest that Hh inhibition

by GANT61 up-regulates the expression of Bnip3, at least in part, through activation of the MEK/ERK signaling pathway. As activation or inhibition of the Hh signaling pathway did not affect the levels of NF-κB, p53 and DNMT1/DNMT3a, these molecules do not appear to be involved in GANT61-induced up-regulation of Bnip3 in HCC cells. The role of autophagy in caner development and progression is complex. Whereas deficiency of autophagy can predispose to the initiation of tumor development, excessive or prolonged activation of autophagy may promote cancer cell death.[10] Paradoxically, autophagy is also known to enhance cancer cell survival in response to some environmental and cellular stresses (e.g., nutrient

deprivation, organelle damage, hypoxia, or therapeutic stress) and causes resistance to antineoplastic therapies. In this study we attempted to explore whether autophagy see more induced by GANT61 in HCC cells is a cell death or survival mechanism. We provided in vitro and in vivo evidence that inhibition of Gli by GANT61 induces both autophagy and apoptosis in HCC cells and that blockage of autophagy reverses GANT61-induced apoptosis and cytotoxicity. Although the role of autophagy in cell survival and death may depend on specific agents and cell types, our data clearly demonstrate that autophagy contributes to HCC cell apoptosis induced by the Gli inhibitor GANT61, a promising new anticancer drug, and by the multikinase inhibitor sorafenib, the only FDA-approved drug for target therapy of HCC. Inhibition of Hh signaling has been attempted in various human cancer models. Several natural and synthetic pharmacologic agents for modulation of Hh activity have been identified and developed. Historically, Smo antagonists including cyclopamine and GDC-0449 have been used to abrogate Montelukast Sodium Hh signaling in human cancers, with moderate success. A potentially more potent target lies in the family of Gli

transcription factors, which are the final arbiters of transcriptional regulation in the Hh signaling pathway.[26] GANT61 is a recently identified small molecule inhibitor of Gli, which has been shown to effectively block Gli-1 and Gli-2 activities and induce more significant cytotoxicity in human cancer cells than Smo antagonists.[26] In HCC cells, we observed that the Gli inhibitor GANT61 induced more prominent autophagy and apoptotic cell death compared to the Smo inhibitor GDC-0449. In conclusion, this study shows that the Hh signaling pathway importantly regulates autophagy and that inhibition of Hh signaling activates autophagy in human HCC cells at least in part through induction of Bnip3, which prevents Beclin-1 binding to Bcl-2. Furthermore, we show that autophagy contributes to GANT61-induced apoptosis and inhibition of growth in HCC cells.