Aberrant p16 methylation as an early diagnostic marker in blood of hepatocellular carcinoma patients

Background Alpha-fetoprotein (AFP) is currently used for serologic screening in hepatocellular carcinoma (HCC) but with low sensitivity ranging 41–65% with a high rate of false-negative and false-positive results. For the hypermethylation of the p16 inhibitor of cyclin-dependent kinase 4 (p16INK4A), a tumor suppressor gene results in the uncontrolled division of cells. This suggests that the loss of p16INK4A function due to promoter methylation may be an early event in HCC pathogenesis so the study aimed to assess aberrant p16INK4A gene methylation as an early diagnostic marker in HCC patients. Results Our study revealed a highly significant increase of p16INK4A methylation in patients versus controls (Fisher, 36.11; p < 0.01). P16INK4A methylation was detected in 86.6% (26/30) and none of the controls were methylated (100% specificity) compared to the low sensitivity of AFP 65.38% at a cutoff value of 28 ng/mL. Data revealed non-significant difference of p16INK4A methylation status between different HCC Barcelona stages (Fisher, 0.055; p > 0.05). While, AFP levels were statistically significantly higher in stages B and C (median = 243,400 ng/mL, respectively, when compared to stage A (median = 10 ng/mL) (H:16.667, p < 0.01)). Conclusion Early diagnosis of HCC can be achieved through the detection of p16INK4A gene methylation in chronic liver disease (CLD) patients with normal serum AFP especially in known cirrhotic patients that deteriorate clinically without apparent etiology.

Evaluation of UHRF1 and P16INK4A expression levels in newly diagnosed AML patients

Introduction: Gene mutation is an infrequent cause of tumor suppressor gene (TSG) defect in de novo AML patients. Instead, it seems that leukemic cells employ epigenetic tricks to attenuate the negative impacts of intact TSGs. Ordinarily, critical TSGs, such as p16INK4A, is hyper-methylated in AML blasts under the impact of master epigenetic regulators, such as UHRF1. In this study, we investigated the correlation between UHRF1 and p16INK4A gene expression levels in newly diagnosed AML patients. Methods: Bone marrow and peripheral blood samples were obtained from 50 newly diagnosed AML patients and 18 healthy normal control subjects. Gene expression levels of UHRF1 and P16INK4A were surveyed using SYBR Green Quantitative Real-time PCR. Statistical analyses were done using SPSS statistical software 21.0. Results: P16INK4A gene expression showed reduced levels in 80.64% of patients above 45 years of age, while only 32% of patients below 45 years had reduced expression levels. The Spearman correlation test also demonstrated a significant negative correlation between UHRF1 and p16INK4A gene expression levels in AML patients, which was not observed in the control group (r=0.343 and P= 0.015). Conclusion: Regarding the age-related patterns of UHRF1 and p16INK4A gene expression, and also the presence of negative correlation between them, we conclude that UHRF1 may potentially be involved in p16INK4A down-regulation in elderly AML patients, which may subsequently facilitate the progression of AML in older ages.