Promoter hypermethylation in primary squamous cell carcinoma of the oral cavity and oropharynx: a study of a Brazilian cohort

Abstract

Epigenetic silencing of cancer-related genes plays an important role in oral/oropharyngeal squamous cell carcinoma (OSCC). We evaluated promoter hypermethylation of 4 cancer-related genes in OSCCs of a Brazilian cohort and determined its relationship with exposure to alcohol, tobacco, HPV infection and clinicopathological parameters. CDKN2A (cyclin-dependent kinase inhibitor 2A or p16), SFN (stratifin or 14-3-3 σ), EDNRB (endothelin receptor B) and RUNX3 (runt-related transcript factor-3) had their methylation patterns evaluated by MSP analysis in OSCC tumors (n = 45). HPV detection was carried out by PCR/RFLP. Aberrant methylation was detected in 44/45 (97.8 %) OSCC; 24.4 % at CDKN2A, 77.8 % at EDNRB, 17.8 % at RUNX3 and 97.8 % at SFN gene. There was no significant association between methylation patterns and clinical parameters. HPV (subtype 16) was detected in 3 out of 45 patients (6 %). Our findings indicate that HPV infection is uncommon and methylation is frequent in Brazilian OSCCs, however, EDNRB and SFN gene methylation are not suitable OSCC biomarkers due to indistinct methylation in tumoral and normal samples. In contrast, CDKN2A and RUNX3 genes could be considered differentially methylated genes and potential tumor markers in OSCCs.

Differences in methylation profiles between HPV-positive and HPV-negative oropharynx squamous cell carcinoma

“…Seventeen articles met the inclusion criteria and were eligible for further analysis. [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] The main reasons for exclusion were duplicates and studies not investigating correlation between HPV status and methylation status in OPSCC.…”

“…28,33,34,44 In other publications studying overall HNSCC, OPSCC subgroup size ranged from 9% to 80% of the total study population. [29][30][31][32][35][36][37][38][39][40][41][42][43] There was only one study that reported the distribution of average age, nicotine and alcohol consumption between HPV-positive and HPV-negative tumors of which promoter methylation was evaluated. 34 The mean age in HPV-positive tumors was 56.9 compared with 58.4 in HPV-negative tumors.…”

“…28,29,32,[34][35][36][37]40 Six used fresh frozen (FF) tissue or both. 31,38,[41][42][43][44] Three studies did not report used material. 30,33,39 The majority of studies used polymerase chain reaction (PCR) to detect HPV 16 DNA.…”

“…33,42,44 Thirteen studies evaluated promoter methylation in selected genes in association with HPV status. [28][29][30][31][33][34][35][36][37][41][42][43][44] Three studies investigated global methylation in association with HPV status. 32,38,39 One study examined both promoter methylation and global methylation, in association with HPV status.…”

“…28 Most studies did not mention how methylation was interpreted. [30][31][32][33][34][35][36][37][38][39][40][41] The main features of the 17 studies eligible for systematic review are summarized in Table 1.…”