Sulfatase 2 protects hepatocellular carcinoma cells against apoptosis induced by the PI3K inhibitor LY294002 and ERK and JNK kinase inhibitors.

Publication Type:

Journal Article

Source:

Liver international : official journal of the International Association for the Study of the Liver, Volume 30, Issue 10, p.1522-8 (2010)

Keywords:

Apoptosisdigestive disease, digestive deseases bcl-Associated Death Proteindigestive disease, digestive deseases Blotting, Westerndigestive disease, digestive deseases Carcinoma, Hepatocellulardigestive disease, digestive deseases Caspase 3digestive disease, digestive deseases Caspase 7digestive disease, digestive deseases Cell Line, Tumordigestive disease, digestive deseases Cell Survivaldigestive disease, digestive deseases Chromonesdigestive disease, digestive deseases Cyclin D1digestive disease, digestive deseases Extracellular Signal-Regulated MAP Kinasesdigestive disease, digestive deseases Humansdigestive disease, digestive deseases Immunohistochemistrydigestive disease, digestive deseases JNK Mitogen-Activated Protein Kinasesdigestive disease, digestive deseases Liver Neoplasmsdigestive disease, digestive deseases Morpholinesdigestive disease, digestive deseases Phosphatidylinositol 3-Kinasesdigestive disease, digestive deseases Phosphorylationdigestive disease, digestive deseases Protein Kinase Inhibitorsdigestive disease, digestive deseases Proto-Oncogene Proteins c-aktdigestive disease, digestive deseases Proto-Oncogene Proteins c-bcl-2digestive disease, digestive deseases Reverse Transcriptase Polymerase Chain Reactiondigestive disease, digestive deseases RNA Interferencedigestive disease, digestive deseases Signal Transductiondigestive disease, digestive deseases Sulfotransferasesdigestive disease, digestive deseases Transfection

Abstract:

BACKGROUND: Sulfatase 2 (SULF2), an extracellular heparan sulphate 6-O-endosulphatase, has an oncogenic effect in hepatocellular carcinoma (HCC) that is partially mediated through glypican 3, which promotes heparin-binding growth factor signalling and HCC cell growth. SULF2 also increases phosphorylation of the anti-apoptotic Akt kinase substrate GSK3β and SULF2 expression is associated with a decreased apoptotic index in human HCCs.

METHODS: We investigated the functional and mechanistic effects of SULF2 on drug-induced apoptosis of HCC cells using immunohistochemistry, Western immunoblotting, gene transfection, real-time quantitative polymerase chain reaction, MTT and apoptosis assays and immunocytochemistry.

RESULTS: The increased expression of SULF2 in human HCCs was confirmed by immunohistochemistry and immunoblotting. Treatment with inhibitors of MEK, JNK and PI3 kinases decreased the viability of SULF2-negative Hep3B HCC cells and induced apoptotic caspase 3 and 7 activity, which was most strongly induced by the PI3K inhibitor LY294002. Forced expression of SULF2 in Hep3B cells significantly decreased activity of the apoptotic caspases 3 and 7 and induced resistance to LY294002-induced apoptosis. As expected, LY294002 inhibited activation of Akt kinase by PI3K. Conversely, knockdown of SULF2 using an shRNA construct targeting the SULF2 mRNA induced profound cell growth arrest and sensitized the endogenously SULF2-expressing HCC cell lines Huh7 and SNU182 to drug-induced apoptosis. The effects of knockdown of SULF2 on HCC cells were mediated by decreased Akt phosphorylation, downregulation of cyclin D1 and the anti-apoptotic molecule Bcl-2, and upregulation of the pro-apoptotic molecule BAD.

CONCLUSION: The prosurvival, anti-apoptotic effect of SULF2 in HCC is mediated through activation of the PI3K/Akt pathway.