PI 3-kinase/Akt and STAT3 are required for the prevention of TGF-β-induced Hep3B cell apoptosis by autocrine motility factor/phosphoglucose isomerase

We established Hep3B cells stably-expressing wild-type and mutated AMF/PGI with differing enzymatic activities in order to investigate how AMF/PGI affects TGF-β-induced apoptosis, and demonstrated that AMF/PGI against TGF-β-induced apoptosis was correlated with its enzymatic activity. AMF/PGI did not alter TGF-β-receptor expression nor affect TGF-β-induced PAI-1 gene promoter or Smad3/4 activity. AMF/PGI induced PI 3-kinase activity, IRS and Akt phosphorylation, which can further regulate BAD phosphorylation. Constitutively-active p110 enhanced AMF/PGI-mediated anti-apoptosis activity, and dominant negative Akt alleviated anti-TGF-β-induced apoptosis. We also demonstrated that STAT3 is a weak anti-apoptotic agent but has an increased anti-apoptotic effect in cooperation with PI 3-kinase/Akt.