Relationship of p16 Methylation Status and Serum α-Fetoprotein Concentration in Hepatocellular Carcinoma Patients

Abstract

Detection of tumor-derived genetic and epigenetic alterations in plasma and serum may have a profound impact on the noninvasive diagnosis of cancers among high-risk populations (1)(2)(3). Chronic hepatitis infection and cirrhosis are well-documented risk factors for hepatocellular carcinoma (HCC) (4). However, patients with chronic hepatitis/cirrhosis may develop HCC only after many years. One long-sought goal in this field, therefore, has been the development of sensitive, specific, and noninvasive blood tests for the early detection and monitoring of HCC (5). A well-established conventional marker for HCC, serum α-fetoprotein (AFP), has limitations for cancer screening because high-risk individuals with AFP concentrations within the reference interval may have already developed HCC at an advanced stage (6)(7). Hypermethylation of p16 , a cyclin-dependent kinase inhibitor gene that regulates cell cycling, has been found frequently in human cancers, including HCC (3)(8). Using methylation-specific PCR (MSP), we analyzed p16 promoter methylation status in 100 plasma and serum samples from HCC patients, controls with chronic hepatitis/cirrhosis, and healthy subjects. Of particular diagnostic interest, we investigated the relationship of p16 methylation status and the serum AFP concentration. With informed consent and ethics approval, peripheral blood samples were obtained from 45 HCC patients before surgical resection, 35 non-HCC patients with chronic hepatitis/cirrhosis, and 20 healthy volunteers. The diagnosis of HCC was confirmed histopathologically in liver biopsy and was based on serum AFP concentration ≥500 μg/L, ultrasound examination with computed tomography, or hepatic angiography as appropriate. Tumor specimens were collected from the HCC patients after surgery, and DNA was extracted using a QIAamp Tissue Kit (Qiagen). Peripheral blood samples were centrifuged at 3000 g , and plasma and serum samples were collected from EDTA-containing and plain tubes, respectively. DNA was …