Aberrant methylation of p16, DLEC1, BLU and E-cadherin gene promoters in nasopharyngeal carcinoma biopsies from Tunisian patients

Background: Aberrant methylation of tumor suppressor gene (TSG) promoters has been extensively investigated in nasopharyngeal carcinomas (NPC) from South East Asia but not from North Africa. Patients and Methods: The methylation status of p16, deleted in lung and esophageal cancer (DLEC1), zinc finger, MYND-type containing 10 (BLU) and E-cadherin gene promoters was investigated in 44 Tunisian NPC biopsies and three NPC xenografts, by methylation-specific PCR (MSP) combined with a quantitative assessment of some of the samples. Results: The frequencies of aberrant promoter methylation were similar to previous figures reported for Asian series: p16 27/44 (65%), DLEC1 38/44 (863%), BLU 15/44 (34.1% ) and E-cadherin 35/44 (79.5%). Although in other malignancies, aberrant promoter hypermethylation increases with patient age, it was at the same high frequency in the juvenile and adult forms of Tunisian NPCs. However, there was a strong association between aberrant methylation of E-cadherin promoter and lymph node invasion (p<0.01). In addition, aberrant methylation of the BLU promoter was significantly correlated with an undifferentiated histological type (p=0.03). Conclusion: Aberrant methylation of tumor suppressor genes occurs with the same high frequency in NPCs from North Africa as in South East Asia, regardless of patient age.