R-Etodolac decreases β-catenin levels along with survival and proliferation of hepatoma cells

Background/Aims: Inhibition of hepatoma cells by cyclooxygenase (COX)-2-dependent and -independent mechanisms has been shown previously. Here, we examine the effect of Celecoxib, a COX-2-inhibitor and R-Etodolac, an enantiomer of the nonsteroidal anti-inflammatory drug Etodolac, which lacks COX-inhibitory activity, on the Wnt/β-catenin pathway and human hepatoma cells. Methods: Hep3B and HepG2 cell lines were treated with Celecoxib or R-Etodolac, and examined for viability, DNA synthesis, Wnt/β-catenin pathway components, and downstream target gene expression. Results: Celecoxib at high doses affected β-catenin protein by inducing its degradation via GSK3β and APC along with diminished tumor cell proliferation and survival. R-Etodolac at physiological doses caused decrease in total and activated β-catenin protein secondary to decrease in its gene expression and post-translationally through GSK3β activation. In addition, increased β-catenin-E-cadherin was also observed at the membrane. An associated inhibition of β-catenin-dependent Tcf reporter activity, decreased levels of downstream target gene products glutamine synthetase and cyclin-D1, and decreased proliferation and survival of hepatoma cells was evident. Conclusions: The antitumor effects of Celecoxib (at high concentrations) and R-Etodolac (at physiological doses) on HCC cells were accompanied by the down-regulation of β-catenin demonstrating a useful therapeutic strategy in hepatocellular cancer.