Unusually high incidence of polyomavirus JC infection in the higher grade of colorectal cancer tissues in Taiwan

Abstract

Introduction: The human JC polyomavirus (JCPyV) has been detected in colorectal cancer (CRC) tissues and is suggested to contribute to CRC tumorigenesis. The rearrangement of the JCPyV regulatory region is supposedly associated with CRC development. The progression of CRC involves the stepwise accumulation of mutations. The large tumor antigen (LT) of JCPyV can trigger uncontrolled cell cycle progression by targeting oncogenes, and tumor suppressor genes, and causing chromosome instability. Few studies have focused on the presence of JCPyV DNA in the higher grade of CRC tissues.

Methods: We collected 95 tissue blocks from samples of stages I, II, III, and IV CRC. Nested PCR targeting the regulatory region of the viral genome was performed to determine the presence of JCPyV DNA in the various stages of colorectal cancer tissues.

Results: The nested PCR results showed that the positive rate of JCPyV DNA increased with the progression of CRC stages. The archetypal-like, non-rearrangement genotype of JCPyV with subtle mutations was the major genotype found in CRC samples.

Conclusions: This finding in our study suggests that there may be an association between JCPyV and CRC progression.

Keywords: Colorectal cancer; DNA virus; JCPyV; Nested PCR; Tumor progression.

Fig. 1

Electrophoresis of DNA fragments in stage I CRC samples. A Viral regulatory region was amplified by nested PCR, using JC-BK-specific primers. B Beta-actin gene was amplified by specific primers. The product was analyzed by electrophoresis in 2.5% agarose gel. Following electrophoresis, the gel was stained with ethidium bromide and photographed under UV light. JCPyV and BKPyV genomic DNA were cloned into a plasmid and used as a positive control. M marker, Lane numbers represent the number of the tissue sample involved. N negative control (without DNA)

Fig. 2

Electrophoresis of DNA fragments in stage II CRC samples. A Viral regulatory region was amplified by nested PCR, using JC-BK-specific primers. B Beta-actin gene was amplified by specific primers. The product was analyzed by electrophoresis in 2.5% agarose gel. Following electrophoresis, the gel was stained with ethidium bromide and photographed under UV light. JCPyV and BKPyV genomic DNA were cloned into a plasmid and used as a positive control. M marker, Lane numbers represent the number of the tissue sample involved. N negative control (without DNA)

Fig. 3

Electrophoresis of DNA fragments in stage III CRC samples. A Viral regulatory region was amplified by nested PCR, using JC-BK-specific primers. B Beta-actin gene was amplified by specific primers. The product was analyzed by electrophoresis in 2.5% agarose gel. Following electrophoresis, the gel was stained with ethidium bromide and photographed under UV light. JCPyV and BKPyV genomic DNA were cloned into a plasmid and used as a positive control. M marker, Lane numbers represent the number of the tissue sample involved. N negative control (without DNA)

Fig. 4

Electrophoresis of DNA fragments in stage IV CRC samples. A Viral regulatory region was amplified by nested PCR, using JC-BK-specific primers. B Beta-actin gene was amplified by specific primers. The product was analyzed by electrophoresis in 2.5% agarose gel. Following electrophoresis, the gel was stained with ethidium bromide and photographed under UV light. JCPyV and BKPyV genomic DNA were cloned into a plasmid and used as a positive control. M marker, Lane numbers represent the number of the tissue sample involved. N negative control (without DNA). T: a tested sample was run aligned with the CRC tissues

Fig. 5

Schematic representation of the JCPyV regulatory region identified in the CRC tissues. Regulatory regions of CY and TW4 are shown for comparison. (ATCG): point mutation; (^) insertion; (□) deletion