Significance of P16INK4A Expression and PTEN Loss of Heterozygosity in Human Papilloma Virus-related Oral Squamous Cell Carcinoma.

Abstract

p16 and PTEN are tumor suppressor genes. Loss of these molecules in oral squamous cell carcinoma (OSCC) has been studied worldwide. In this study, we explored whether p16 cooperates with inactive PTEN during the pathogenesis of OSCC, especially in regard to tumor aggressiveness and proliferation. Immunocytochemistry and western blot analysis were used to examine the levels of p16 and PTEN. Sequencing analysis was performed to identify mutations in the PTEN gene and HPV infection. Fluorescence in situ hybridization was used to examine the presence of the PTEN locus. PTEN analysis showed high positivity in T4 samples. HPV-positive tumors correlated with tabagism, tumor size 3 and 4, disease stages 3 and 4, presence of lymph node metastasis (N1) and poor differentiation. Immunoexpression of p16 was strongly correlated with the presence of HPV. PTEN demonstrated a higher reactivity in advanced disease stages and p16 was strongly associated with HPV. Viral presence decreases tumor aggressiveness. Patients with advanced stage lesions demonstrated lower survival rate.