Journal Article

<i>N</i>-acetylglucosaminyltransferase V confers hepatoma cells with resistance to anoikis through EGFR/PAK1 activation

Jing Liu, Haiou Liu, Weijuan Zhang, Qian Wu, Weisi Liu, Yidong Liu, Deng Pan, Jiejie Xu and Jianxin Gu

in Glycobiology

Published on behalf of Society for Glycobiology

Volume 23, issue 9, pages 1097-1109
Published in print September 2013 | ISSN: 0959-6658
Published online June 2013 | e-ISSN: 1460-2423 | DOI: http://dx.doi.org/10.1093/glycob/cwt049
N-acetylglucosaminyltransferase V confers hepatoma cells with resistance to anoikis through EGFR/PAK1 activation

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Elevated expression and activity of N-acetylglucosaminyltransferase V (Mgat5) in hepatocellular carcinoma (HCC) is a common early event involved in tumor invasion during hepatocarcinogenesis. A better understanding of the functional role and the molecular mechanism for Mgat5-targeted protein and downstream signaling pathway behind hepatoma invasion and metastasis is urgently needed. Here, we show that Mgat5 overexpression promoted anchorage-independent growth and inhibited anoikis in hepatoma cells. This effect was reversed by glycosyltransferase inactive mutant Mgat5 L188R transfection, α-mannosidase II inhibitor swainsonine treatment and N-acetyl glucosamine (GlcNAc) phosphotransferase (GPT) inhibitor tunicamycin administration. Mgat5 overexpression increased p21-activated kinase 1 (PAK1) expression and shRNA-mediated PAK1 knockdown and kinase inactivation with kinase dead mutant PAK1 K299R coexpression or allosteric inhibitor P21-activated kinase inhibitor III (IPA3) treatment reversed anoikis resistance in Mgat5-overexpressed hepatoma cells. Furthermore, Mgat5 overexpression upregulated β-1-6-GlcNAc branched N-glycosylation and following phosphorylation of epidermal growth factor receptor (EGFR) in hepatoma cells. EGFR tyrosine kinase inhibitors AG1478 and Iressa treatment declined anchorage-independent growth and anoikis resistance, which could be rescued by constitutive active mutant PAK1 T423E coexpression in Mgat5-overexpressed hepatoma cells. Conversely, knockdown of Mgat5 reduced EGFR/PAK1-dependent anoikis resistance, which could be reversed by PAK1 T423E. These results identified Mgat5-mediated β-1-6-GlcNAc branched N-glycosylation and following activation of EGFR as a potential novel upstream molecular event for PAK1-induced anoikis resistance in hepatoma cells, implicating that molecular targeted therapeutics against Mgat5/EGFR/PAK1 might open a new avenue for personalized medicine in advanced-stage HCC patients.

Keywords: Anoikis; EGFR; HCC; Mgat5; PAK1

Journal Article.  5772 words.  Illustrated.

Subjects: Carbohydrates

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