BioScience Trends. 2014;8(2):101-110. (DOI: 10.5582/bst.8.101)
Expression of ankyrin repeat and SOCS box containing 4 (ASB4) confers migration and invasion properties of hepatocellular carcinoma cells.
Au V, Tsang FH, Man K, Fan ST, Poon RTP, Lee NP
Ankyrin repeat and SOCS box containing 4 (ASB4) involves in physiological process of ubiquitin-mediated proteasomal degradation. Our previous study demonstrated high expression of ASB4 in hepatocellular carcinoma (HCC) cell lines. This study further reveals its clinical implications and tumorigenic properties in HCC. Analysis of 217 HCC gene expression profiles followed by validation in a separate cohort of 50 cases illustrated high ASB4 in HCC. Among the 50 cases, 54% of tumors exhibited more than 2-fold up-regulation of ASB4. Elevated ASB4 associated with low serum level of a HCC serological marker alpha-fetoprotein (AFP), postulating of its use to differentiate AFP-negative HCC. Suppression of ASB4 in PLC and MHCC97-L HCC cells hindered the cell migration and invasion. Reciprocally, enhanced migration rate was measured when ASB4 was ectopically expressed in Hep3B HCC cells. Cross comparison of results derived from in silico predictions of seed-matched sequences and by analyzing human HCC databases with matched microRNA and gene expression profiles, microRNA-200 (miR-200) family members including miR-200a and miR-200b were predicted to regulate ASB4 expression in HCC. MiR-200a showed inversed expression level with ASB4 in several of studied HCC cell lines. Dual luciferase reporter assay confirmed the presence of miR-200a binding site on the 3’ untranslated region of ASB4. Reduced ASB4 level was noticed under the influence of miR-200a mimic treatment, for which this mimic-induced effect was neutralized with miR-200a inhibitor. In conclusion, this study demonstrates for the first time on the involvement of ASB4 in HCC and that its level is regulated by miR-200a.