Quantitative Plasma Hypermethylated DNA Markers of Undifferentiated Nasopharyngeal Carcinoma

Abstract

Purpose: Gene-specific methylation is common in primary undifferentiated nasopharyngeal carcinoma (NPC). DNA released from apoptotic or necrotic cell death including those aberrantly methylated promoter DNA of cancer cells is absorbed into the circulation as cell-free plasma DNA of the patient. This study aims at evaluation of the potential use of methylated gene promoter DNA as a serological tumor marker of primary and potentially salvageable local or nodal recurrent NPC.Experimental Design: The quantity of plasma hypermethylated gene promoters of CDH1, DAPK1, p15, p16, RASSF1A, and MLH1 of 41 NPC patients before treatment and 43 normal individuals were studied using real-time quantitative PCR. The post-treatment plasma hypermethylated CDH1, DAPK1, and p16 were also measured in 13 NPC patients with locoregional recurrence and 17 patients in remission.Results: Concentrations of cell-free circulating DNA were significantly higher in NPC patients than normal controls (28.79 ng/ml versus 16.57 ng/ml, respectively). There was no significant difference in plasma DNA concentration of EBV-positive and -negative normal individuals. Methylated DNA was detectable in plasma of NPC patients before treatment including 46% for CDH1, 42% for p16, 20% for DAPK1, 20% for p15, and 5% for RASSF1A. Hypermethylated MLH1 was not detected in plasma of all of the NPC patients and normal individuals. Aberrantly hypermethylated promoter DNA of at least one of the five genes was detectable in 29 of 41 (71%) plasma of NPC patients before treatment. Hypermethylated promoter DNA of at least one of the three genes (CDH1, DAPK1, and p16) was detectable in post-treatment plasma of 5 of 13 (38%) recurrent NPC patients and none of the patients in remission.Conclusions: Our results suggested that cell-free circulating methylated gene promoter DNA is a possibly useful serological marker in assisting in screening of primary and potentially salvageable local or regional recurrent NPC.

Mixed Exocrine-Neuroendocrine Carcinoma of the Nasal Cavity: Clinico-Pathologic and Molecular Study of a Case and Review of the Literature

“…Promoter hypermethylation of DAPK1 was also found to be restricted to the neuroendocrine component. Interestingly, the aberrant methylation of DAPK1 is considered an important epigenetic event in nasopharyngeal carcinomas [34] and has been evaluated as an early molecular marker of subclinical presence of this neoplasm [35,36].…”

Clinicopathological significance of RASSF1A reduced expression and hypermethylation in hepatocellular carcinoma

“…It has been suggested that RASSF1A methylation is one of the most common aberrations so far identified in human cancers and that the loss of the functional protein may promote the development of many human tumors. Hypermethylation of the RASSF1A has been detected frequently in the tissues of different cancers [10][11][12][13][14][15][16][17], while in the body fluid, methylation of RASSF1A promoter has also been documented in 50% sputum and 84% serum from lung cancer [30], 35% urine from bladder cancer [15], 56-60% serum from breast caner [31][32][33], and 5% serum from undifferentiated nasopharyngeal carcinoma [34], which indicated the value of RASSF1A methylation in DNA for the early-stage diagnosis of tumors. Detection of methylated DNA has then been suggested as a potential biomarker for early detection of cancer.…”

DAPk Protein Family and Cancer

“…By analyzing DAPk methylation status, it was possible to detect urinary bladder cancer from voided urine; head and neck cancer from saliva, mouth rinsing fluid or nasopharyngeal swab or serum; colon and breast cancer from serum; lung cancer from sputum, bronchial brush samples or serum; and cervix cancer from cervical cytology specimens. [51][52][53][54][55][56][57][58][59][60][61] Consequently, DAPk downregulation by methylation is a cancerspecific event, which may be used to specifically detect malignant cells.…”