Human papillomavirus genotypes in penile cancers from Japanese patients and HPV-induced NF-κB activation

The causal relationship between chronic inflammation and cancer is widely accepted. Numerous investigations have identified nuclear factor-κB (NF-κB) as an important modulator in driving chronic inflammation to cancer. This study aimed to determine the prevalence of human papillomavirus (HPV) in penile cancer in Japanese patients and whether NF-κB is subsequently overexpressed in penile cancer. Thirty-four specimens of penile tissue (16 malignant and 18 benign cases) were examined to determine the association of HPV infection. An in situ hybridization (ISH) method was used to detect and localize HPV-DNA. A sensitive HPV polymerase chain reaction (PCR) procedure was used for the detection of HPV-DNA, and DNA sequencing was used to identify the HPV genotype. HPV-DNA was detected in 37.5 and 75% of cases of penile cancer, using ISH and PCR, respectively. Our efforts to detect HPV genotypes were unsuccessful as HPV-DNA could not be extracted from these materials. Using ISH, a prevalence of 68.2% of HPV infection was found in penile cancer in Kenyan patients in east Africa. In the present study, all 9 HPV-positive cases, (100%) were NF-κB-positive in the nucleus and/or cytoplasm. In contrast, of the 25 HPV-negative cases, 15 (60%) were NF-κB-positive in the nucleus and/or cytoplasm. Therefore, ISH is a method which is able to prove infection of a large quantity of HPV more effectively when compared with PCR. Thus, a large quantity of HPV infection leads to the activity of NF-κB. The most prevalent genotype was the HPV-22 found in 83.3% of the penile cancer cases. In addition, HPV-11 was found in 81.8% of the non-cancer cases. For cases with a high level of infection, the activity of NF-κB increased compared with those with a low level of HPV infection