Two specific inhibitors of the phosphatidylinositol 3-kinase LY294002 and wortmannin up-regulate beta1,4-galactosyltransferase I and thus sensitize SMMC-7721 human hepatocarcinoma cells to cycloheximide-induced apoptosis

Mol Cell Biochem. 2007 Oct;304(1-2):361-7. doi: 10.1007/s11010-007-9519-1. Epub 2007 Jun 8.

Abstract

Previous study indicated that beta1,4-galactosyltransferase I (beta1,4GT1) was up-regulated by cycloheximide (CHX) and thus enhanced apoptosis induced by CHX in SMMC-7721 cells. In this study, we reported that constitutively active Akt protein (myr-Akt) inhibited CHX-induced apoptosis in SMMC-7721 cells through down-regulating beta1,4GT1. However, the two PI3K inhibitors LY294002 and wortmannin treatment up-regulated beta1,4GT1 through enhancing Sp1 protein expression and consequently increased CHX-induced SMMC-7721 cells apoptosis. Besides, our results suggested that beta1,4GT1 and cell surface galactose residues synthesized by elevated beta1,4GT1 played an important role in SMMC-7721 cells apoptosis treated with CHX and PI3K inhibitor together. Moreover, we found that CHX accentuated beta1,4GT1 through down-regulating Akt expression to mediate SMMC-7721 cells apoptosis. Taken together, PI3K inhibitors LY294002 and wortmannin up-regulated beta1,4GT1 and enhanced CHX-induced apoptosis in SMMC-7721 cells, which suggested that PI3K inhibitors might have therapeutic potential when combined with CHX in the treatment of hepatoma.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Androstadienes / pharmacology*
  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use
  • Apoptosis / drug effects*
  • Carcinoma, Hepatocellular / drug therapy
  • Carcinoma, Hepatocellular / genetics*
  • Cell Line, Tumor
  • Chromones / pharmacology*
  • Cycloheximide / pharmacology*
  • Drug Evaluation, Preclinical
  • Drug Synergism
  • Galactosyltransferases / genetics*
  • Galactosyltransferases / physiology
  • Gene Expression Regulation, Enzymologic / drug effects
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • Liver Neoplasms / drug therapy
  • Liver Neoplasms / genetics*
  • Morpholines / pharmacology*
  • Phosphatidylinositol 3-Kinases
  • Substrate Specificity
  • Up-Regulation / drug effects
  • Wortmannin

Substances

  • Androstadienes
  • Chromones
  • Morpholines
  • 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
  • Cycloheximide
  • Galactosyltransferases
  • beta1,4-galactosyltransferase, human
  • Phosphatidylinositol 3-Kinases
  • Wortmannin