Aim: To demonstrate the presence and biological activity of human papilloma virus (HPV) in gastric cancer (GAC) tissues.
Methods: The study involved 84 surgically treated patients with gastric adenocarcinoma, regardless of the clinical stage of the disease. The presence of HPV DNA of high oncogenic risk types in formalin-fixed, paraffin-embedded tumor samples was determined using quantitative polymerase chain reaction analysis. A stringent protocol of prevention of cross- and environmental contamination was applied during DNA isolation, and amplification, as well as confirmation of the biological activity of the virus in tumor cells, was implemented. The study utilized the Real-time High Risk HPV test, which detects the DNA of 14 HPV subtypes that are considered to have high oncogenic potential. The overexpression of the p16(INK4a) protein assessed immunohistochemically was considered confirmation of the HPV infection.
Results: Among the 89 patients initially included in the study group, diagnostic results were obtained for 84 individuals. In five cases, either the histopathological material was too scant to isolate the necessary amount of DNA, or the isolated DNA was significantly degraded, resulting in the failure of internal control amplification within the predefined number of 35 cycles. Those patients were excluded from further analysis. The amplification of HPV DNA was demonstrated in none of the 84 tissue samples; thus, all cases were considered to have a negative DNA status of highly oncogenic HPV subtypes. Immunohistochemical staining provided diagnostic results for all of the examined tissue samples, and excluded the accumulation of the p16(INK4a) protein in tumor cells, thus confirming the lack of active HPV infection in all of the individuals.
Conclusion: The study does not confirm the presence or biological activity of HPV in tumor tissues. Thus, the relationship between GAC and HPV infection, in the Central European population seems doubtful.
Keywords: Gastric cancer; Human papilloma virus; P16INK4a expression; Quantitative polymerase chain reaction.