We reported previously that more than one-third (37%) of primary bladder squamous cell carcinomas (SCCs) demonstrate diffuse p16 immunoreactivity independent of gender. This observation made us question whether p16 overexpression in bladder carcinoma is due to human papillomavirus (HPV)-dependent mechanisms.
To determine whether the presence of high-risk HPV (HR-HPV) DNA could be detected in these tumor cells.
Fourteen cases of primary bladder SCC, which were positive for p16 by immunohistochemistry, were probed for the detection of HR-HPV by in situ hybridization and the signal amplification Invader assay. Samples positive for detection of HR-HPV by Invader assay were amplified by using HR-HPV type-specific primers, and amplification products were DNA sequenced.
Detection of HR-HPV by the in situ hybridization method was negative in all cases (0 of 14). However, in 3 of 14 cases (21.4%), the presence of HR-HPV DNA was detected with the Cervista HPV HR Invader assay, which was followed by identification of genotype. All positive cases were confirmed by using HR-HPV type-specific amplification followed by DNA sequencing. Identified HR-HPV genotypes included HPV 16 (2 cases) and HPV 35 (1 case).
High-risk HPV DNA is detectable in a subset of primary bladder SCCs. Based on the well-documented carcinogenic potential of HR-HPV, there is a necessity for additional studies to investigate the role of HR-HPV in bladder carcinogenesis.