Background: Recently, it has been proven that protein gene product 9.5 (PGP9.5) hypomethylation might play an important role in re-expression of the PGP9.5 gene in gallbladder cancer. We previously examined the expression of PGP9.5 in primary colorectal cancer using immunohistochemistry and found that PGP9.5 expression is related to tumor progression and may be useful as a marker for invasive colorectal cancer. These results prompted us to examine the methylation status of the PGP9.5 gene in colorectal cancer.
Materials and methods: The methylation status of the PGP9.5 gene in primary tumors derived from 49 patients with colorectal cancer using a quantitative methylation-specific polymerase chain reaction (qMSP) and the association between the methylation status and the clinicopathological findings was evaluated.
Results: An aberrant methylation of the PGP9.5 gene was detected in 36 out of 49 (73%) primary colon cancer samples. Subsequently, clinicopathological data were tested for their association with the methylation results. Lymph node metastasis was significantly associated with a lower frequency of methylation (p=0.029).
Conclusion: These findings indicated that PGP9.5 was less frequently methylated in metastatic colorectal cancer, suggesting that PGP9.5 hypomethylation might play an important role in re-expression of the PGP9.5 gene in colorectal cancer.