The etiology of colorectal cancer (CRC) remains elusive in spite of major advances in knowledge of this disease and related risk factors. Several studies report the detection of human polyomavirus JC (JCV) in colorectal tumors and some suggest its association with CRC. Since many known human virus associations with cancer are linked to factors such as ethnic and geographical origin, it is interesting to search for the postulated association of JCV with CRC in different populations and regions. In this perspective, the present work was undertaken to assess the presence of JCV in CRC tumors in Tunisia. Fresh biopsies were obtained from both colorectal tumors and adjacent normal tissues of 47 CRC patients. Only tumors diagnosed as adenocarcinomas were included in the present study. Twenty patients with other gastroenterological disorders were taken as controls. DNA was extracted from fresh biopsies or formalin-fixed, paraffin-embedded tissue sections. A region of the viral T-Ag gene was amplified by PCR and the DNA amplicons were subjected to automated sequencing. JCV DNA was found in 22 (46%) of the adenocarcinomas but in none of the normal mucosa biopsies of either CRC or control patients. Sequence analysis indicated that the amplified DNA belonged to a new JCV variant of genotype A. The presence of JCV DNA was correlated with tumor location and grade. The data obtained suggest that JCV may be associated either with a subpopulation of colorectal tumors or with CRC in general, possibly through a hit and run mechanism.
Keywords: Cancer etiology; Colorectal cancer; JC virus; Transformation antigen (T-Ag).