RASSF1A and DOK1 Promoter Methylation Levels in Hepatocellular Carcinoma, Cirrhotic and Non-Cirrhotic Liver, and Correlation with Liver Cancer in Brazilian Patients

Abstract

Hepatocellular carcinoma (HCC) is the second most common cause of cancer mortality worldwide. Most cases of HCC are associated with cirrhosis related to chronic hepatitis B virus or hepatitis C virus infections. Hypermethylation of promoter regions is the main epigenetic mechanism of gene silencing and has been involved in HCC development. The aim of this study was to determine whether aberrant methylation of RASSF1A and DOK1 gene promoters is associated with the progression of liver disease in Brazilian patients. Methylation levels were measured by pyrosequencing in 41 (20 HCC, 9 cirrhotic, and 12 non-cirrhotic) liver tissue samples. Mean rates of methylation in RASSF1A and DOK1 were 16.2% and 12.0% in non-cirrhotic, 26.1% and 19.6% in cirrhotic, and 59.1% and 56.0% in HCC tissues, respectively, showing a gradual increase according to the progression of the disease, with significantly higher levels in tumor tissues. In addition, hypermethylation of RASSF1A and DOK1 was found in the vast majority (88%) of the HCC cases. Interestingly, DOK1 methylation levels in HCC samples were significantly higher in the group of younger (<40 years) patients, and higher in moderately differentiated than in poorly differentiated tumors (p < 0.05). Our results reinforce the hypothesis that hypermethylation of RASSF1A and DOK1 contributes to hepatocarcinogenesis and is associated to clinicopathological characteristics. RASSF1A and DOK1 promoter hypermethylation may be a valuable biomarker for early diagnosis of HCC and a potential molecular target for epigenetic-based therapy.

The Molecular Background Associated with the Progression of Hepatitis C to Hepatocellular Carcinoma

“…In our study, RASSF1A methylation was detected in all HCC cases and in 68.4% of CH cases (being second only to APC). This finding is consistent with Araújo and Gioia et al [25,26] who reported an increase in RASSF1A PM with progression from regenerative conditions (e.g. cirrhosis) to hepatocellular nodules and HCC, as well as with Huang et al [15] and Chan et al [27] who reported RASSF1A methylation in the blood and tissues of HCC patients.…”

Identification of RASSF1A promoter hypermethylation as a biomarker for hepatocellular carcinoma

“… N.A. Blood qMSP Villanueva, 2015 [ 52 ] USA 231 82 221 10 10 Normal Tissue Pyrosequencing Dong, 2015 [ 53 ] China 584 122 190 26 234 Non-tumor Blood Methylight 2 0 0 160 Normal Araújo, 2016 [ 54 ] Brazil 24 15 17 2 7 Non-tumor Tissue Pyrosequencing Liu, 2017 [ 55 ] China 155 77 105 0 50 Normal Blood MSP Mansour, 2017 [ 56 ] Egypt 121 36 41 25 40 Non-tumor Blood MSRE-qPCR 2 …”

Diagnostic role of Wnt pathway gene promoter methylation in non small cell lung cancer

“…To assess DNA hypermethylation frequencies in our cohort and The Cancer Genome Atlas (TCGA) cohort, cut-off values for each gene were obtained from the quantile representing the upper 95% of methylation levels in non-tumor samples [ 19 , 20 ]. Therefore, the percentages of hypermethylation for SFRP1 , SFRP2 , WIF1 and PRKCB were 25.2% (28/111), 7.2% (8/111), 9.0% (10/111) and 21.6% (24/111) with corresponding PMR cut-off values of 13.694, 360.400, 127.500 and 27.494.…”