Molecular and IHC analysis of head and neck carcinomas associated with HPV infection

Head and neck squamous cell carcinomas (HNSCC) are a highly heterogenous disease which can be induced by two main carcinogens - tobacco and/or alcohol, or by HR HPV infection. This work examined 60 paraffin-embedded biopsies of head and neck carcinomas after histological verification. HPV infection, including its specific types in various HNSCC areas, was studied using multiplex qPCR. Expression levels of p16INK4A and p53 were detected by subsequent IHC analysis as being potential diagnostic markers. Based on the assumption that patients with HNSCC could benefit from anti-EGFR therapy (cetuximab), but the predictors are not yet defined, analyses of point mutations of ras genes (Kras, Nras) were carried out using multiplex qPCR and sequence analysis of the Braf gene. All statistical data were processed by Chí-x2 test.HPV infection was detected in 23.34 % of cases with HNSCC, of which 100 % were HPV 16, which is the most frequently infection found in the oropharyngeal region. Using IHC analysis, a positive expression of P16INK4A was detected in 100 % of HPV-positive HNSCC while this expression was discovered to be highly correlated with HPV infection. Furthermore, a correlation between p53 and HPV-negative HNSCC was proved. The mutation incidence was the highest in the Kras gene (codon 12 and codon 146), Nras (codon 12) and Braf. A correlation between tumor location in the oropharyngeal region and Kras mutations was proved. The HPV infection correlated with Kras mutations in case of codon 146 but on the grounds of low amount of output data, these figures could be irrelevant. In one case, c.1808 G>A, protein 603 Arg>Gln mutation was found in the Braf gene but its correlation with head and neck carcinomas has not been described yet (Tab. 2, Fig. 2, Ref. 24). Keywords: head and neck carcinomas, biopsy, HPV types, PCR, p16INK4A, p53, molecular predictors, Kras, Nras, Braf.