Promoter DNA Methylation and mRNA Expression Level of p16 Gene in Oral Squamous Cell Carcinoma: Correlation with Clinicopathological Characteristics
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The aim of this study was to investigate the relationship between p16 methylation and its expression in oral squamous cell carcinoma (OSCC). Also the contribution of clinicopathological factors, HPV infection and smoking in p16 expression and promoter methylation has been investigated. In this study 67 consecutive OSCC patients and 59 normal individuals were enrolled. All patients were candidates for surgery of oral cavity and fresh tumor biopsies were collected and processed for DNA and RNA extraction. Normal gingival tissues were collected from individuals referred to dentistry clinic and considered as controls. All the cases and controls were checked for HPV infection and then promoter methylation and expression of p16 gene were determined using Methylation-specific PCR (MSP) and real-time PCR (QPCR), respectively. Methylation of p16 in tumors and normal tissues were 59.7 and 38.9%, respectively. Most of hypermethylated samples (>82%) were in high grades. P16 methylation was comparable in HPV+ and HPV- patients or smokers. P16 was overexpressed (~3 fold; p = 0.044) in HPV+ tumors, but it was significantly down-regulated in smoker patients (40% of all tumors). Comparison of P16 expression in OSCC tumors with different degrees of promoter methylation further suggest the relationship of methylation rate and down-regulation of P16 expression. The p16 methylation and expression was differentially affected in patients with HPV infection and the smoker cases. Regardless of the influence of environmental factors, it appears that P16 status is useful for classifying patients with OSCC and for influencing treatment strategies in accordance with this classification. Moreover, targeting the upregulation of p16 could be a promising therapeutic option.
KeywordsOSCC HPV Smoking P16 promoter methylation P16 gene expression Iran
This study was financially supported by Tarbiat Modares University and Cancer Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, I.R. Iran. (Grant# 92-02-51-23399).
Compliance with Ethical Standards
Conflict of Interest
The authors have declared that no potential conflict of interest exists.
- 5.Laco J, Nekvindova J, Novakova V, Celakovsky P, Dolezalova H, Tucek L et al (2012) Biologic importance and prognostic significance of selected clinicopathological parameters in patients with oral and oropharyngeal squamous cell carcinoma, with emphasis on smoking, protein p16(INK4a) expression, and HPV status. Neoplasma 59:398–408CrossRefGoogle Scholar
- 20.Alves MK, Ferrasi AC, Lima VP, Ferreira MV, de Moura Campos Pardini MI, Rabenhorst SH (2011) Inactivation of COX-2, HMLH1 and CDKN2A gene by promoter methylation in gastric cancer: relationship with histological subtype, tumor location and helicobacter pylori genotype. Pathobiology 78:266–276CrossRefGoogle Scholar
- 23.Jitani AK, Raphael V, Mishra J, Shunyu NB, Khonglah Y, Medhi J (2015) Analysis of human papilloma virus 16/18 DNA and its correlation with p16 expression in Oral cavity squamous cell carcinoma in north-eastern India: a chromogenic in-situ hybridization based study. J Clin Diagn Res 9:EC04–EC07PubMedPubMedCentralGoogle Scholar
- 33.Bhatia V, Goel MM, Makker A, Tewari S, Yadu A, Shilpi P et al (2014) Promoter region hypermethylation and mRNA expression of MGMT and p16 genes in tissue and blood samples of human premalignant oral lesions and oral squamous cell carcinoma. Biomed Res Int 2014:248419PubMedPubMedCentralGoogle Scholar