OSU-03012, a novel celecoxib derivative, induces reactive oxygen species-related autophagy in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third leading cause of cancer death worldwide. Systemic treatments for HCC have been largely unsuccessful. OSU-03012 is a derivative of celecoxib with anticancer activity. The mechanism of action is presumably 3-phosphoinositide-dependent kinase 1 (PDK1) inhibition. This study investigated the potential of OSU-03012 as a treatment for HCC. OSU-03012 inhibited cell growth of Huh7, Hep3B, and HepG2 cells with IC(50) below 1 mumol/L. In Huh7 cells, OSU-03012 did not suppress PDK1 or AKT activity. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay and flow cytometry analysis indicated that OSU-03012 did not induce cellular apoptosis. Instead, morphologic studies by light and electron microscopy, as well as special biological staining with monodansylcadaverine, acridine orange, and microtubule-associated protein 1 light chain 3, revealed OSU-03012-induced autophagy of Huh7 cells. This OSU-03012-induced autophagy was inhibited by 3-methyladenine. Moreover, reactive oxygen species (ROS) accumulation was detected after OSU-03012 treatment. Blocking ROS accumulation with ROS scavengers inhibited autophagy formation, indicating that ROS accumulation and subsequent autophagy formation might be a major mechanism of action of OSU-03012. Daily oral treatment of BALB/c nude mice with OSU-03012 suppressed the growth of Huh7 tumor xenografts. Electron microscopic observation indicated that OSU-03012 induced autophagy in vivo. Together, our results show that OSU-03012 induces autophagic cell death but not apoptosis in HCC and that the autophagy-inducing activity is at least partially related to ROS accumulation.