Background:
Hepatocellular carcinoma (HCC) is one of the most common cancer with high mortality rate requiring early diagnosis and treatment. Hepatocarcinogenesis is considered a multistep process in which DNA methylation is a type of epigenetic modification and the relationship between methylation and cancer have been the focus of molecular biology researches.
Aims: This study aims to evaluate the frequency of tumor suppressor genes (P16 and RASSF1A) hypermethylation in liver specimens from HCC patients and liver specimens from non-HCC chronic liver disease patients (chronic HCV) and evaluate their clinical significance.
Materials and Methods: This study was conducted on 50 participants (36 male, 14 female): 25 patients having HCV related chronic liver diseases (CLD) without evidence of hepatocellular carcinoma and 25 patients with hepatocellular carcinoma. All patients were selected from outpatient’s clinic of Hepatology, Gastroenterology and Infectious diseases department, Benha University Hospital during the period from June 2013 to December 2014, after approval by ethical committee of Benha faculty of medicine.
Results: Methylated RASSF1A gene in liver specimens was detected in 76% of HCC cases in comparison to 12% of CLD (chronic HCV) group and the frequency of RASSF1A methylation was significantly higher in the HCC patients than CLD patients. Methylated P16 gene in liver specimens was detected in 68% of HCC cases in comparison to 28% of CLD group, and the frequency of P16 methylation was significantly higher in the HCC patients than CLD patients (chronic HCV).
In the present study, the RASSF1A gene expression level was significantly lower in HCC patients who had methylated RASSF1A gene than those who had unmethylated RASSF1A gene. As regards P16 gene, its gene expression level was significantly lower in HCC patients who had methylated P16 gene than those who had unmethylated P16 gene. In the current study, RASSF1A methylation in tissue specimens of HCC group was analyzed by ROC curve showing area under the ROC curve (AUC) of 0.82, sensitivity and specificity of (76%) and (88%) respectively and its accuracy was 82%. As regards P16 methylation, P16 methylation in tissue specimens of HCC group was analyzed by ROC curve showing area under the ROC curve (AUC) of 0.70 , sensitivity and specificity of (68%) and (72%) respectively and its accuracy was 70%.
Conclusion: The frequency of methylated genes (RASSF1A and P16) increases in a stepwise fashion from chronic hepatitis to peak in HCC that may suggest that epigenetic changes occur predominantly in the earlier stages of hepatocarcinogenesis. RASSF1A and P16 promoter hypermethylation play an important role in under expression of their related genes, but there was no significant relationship with the clinical staging of HCC.
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