Aberrant methylation of tumour suppressor genes WT1, GATA5 and PAX5 in hepatocellular carcinoma.

Background: Aberrant hypermethylation of tumour suppressor genes (TSGs) occurring in hepatocellular carcinoma (HCC) could provide a mean of molecular characterisation of this cancer. The aim of this study was to investigate promoter methylation and gene expression of selected TSGs in HCC to identify candidate genes for further validation as potential biomarkers. Methods: Methylation-specific multiplex ligation-dependent probe amplification method was used to measure the methylation status of 25 TSGs in 49 HCC samples and 36 corresponding non-cancerous liver tissue samples. Relative expression of the differentially methylated genes was assessed at the mRNA level using quantitative PCR. Results: We observed a significantly higher methylation in genes WT1, PAX5, PAX6, PYCARD and GATA5 in HCC compared with control samples. The expression of PAX5 was significantly decreased by methylation; conversely methylation of WT1 was associated with higher mRNA levels. Methylation of GATA5 was significantly associated with overall survival and methylation of WT1 and PAX5 significantly varied between patients with ALBI score 1 vs. 2+3. Moreover, PAX5 was significantly more methylated in patients with tumour grade 2+3 vs. grade 1, and methylation of the PAX5 correlated with the patient's age at the time of diagnosis. Conclusions: HCC evince aberrant promoter methylation of WT1, PAX5, PAX6, PYCARD and GATA5 genes. Correlation between GATA5, WT1 and PAX5 methylation and clinical/histological parameters is suggestive of applicability of these markers in non-invasive (epi) genetic testing in HCC.