Impact of HPV detection in colorectal adenocarcinoma: HPV protein and chromogenic in situ hybridization analysis based on tissue microarrays

Human papillomaviruses (HPV)-mediated cervical carcinogenesis represents a well analyzed model of viral implication in epithelial malignant transformation. Concerning colorectal cancer, HPV infection seems to be a significant genetic event in squamous colon epithelia carcinogenesis, but with an unclear role in colon adenocarcinomas (CACs). In the current study, we analyzed 60 CACs based on tissue microarray (TMA) blocks. Cancerous tissues were cored, embedded on a tissue microarray block and analyzed by immunohistochemistry (HPV IHC) and also by chromogenic in situ hybridization (HPV 16/18 DNA CISH) in repetitive serial sections for protein and DNA specific typing detection, respectively. Based on HPV IHC and CISH simultaneous analysis, 16 (26.6%) cases expressed HPV protein. In 7 (11.6%) cores HPV 16/18 DNA signals were detected. Overall HPV protein expression and stage of the examined cases were significantly correlated with HPV CISH results (p=0.0001, p=0.022, respectively). A subset of CACs demonstrated HPV infection associated with stage. In particular, detection of 16/18 HPV DNA types seemed to be a molecular parameter in analyzing genetically CACs, in contrast to HPV protein expression which did not offer significant and specific molecular information.