p16 and p53 in HPV Positive versus HPV Negative Oral Squamous Cell Carcinoma (OSCC): Do Pathways Differ?

Abstract

Background

p16 overexpression and wild-type p53 expression is associated with human papilloma virus (HPV) in cervical and oropharyngeal cancer. Role of HPV-related carcinogenesis in the etiology of oral squamous cell carcinoma (OSCC) is still vague in Indian population. We aimed to explore the expression pattern of p16 and p53 in HPV positive and HPV negative OSCC to elicit differences, if any. Further their effect on survival of patients was studied.

Methods

Thirty-one consecutive HPV positive as well as 31 age and sex matched HPV negative OSCC cases from a case series of 369 histologically diagnosed cases of OSCC were included in this study. HPV was detected by two methods viz. real time PCR and conventional PCR in biopsy samples. p16 and p53 protein expression was assessed by immunohistochemsitry and p16 mRNA expression was quantified with real time PCR using SYBR Green assay.

Results

p16 was expressed in 6(19.4%) HPV positive and in 4(12.9%) HPV negative cases. Overall mutant-type p53 expression in 62 OSCC cases was 54.8%. Out of ten p16 positive cases, eight expressed mutant-type p53 and only 2 cases expressed wild-type p53. Risk factors including oral tobacco consumption and alcohol were present in all these ten p16 positive cases. Survival of patients was not affected by HPV, p16 and p53 status.

Conclusions

Presence of mutated p53 and exposure to tobacco related risk factors in both HPV positive and negative cases suggests existence of p53 related carcinogenesis in HPV positive cases in Indian population.

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