Granzyme B gene polymorphisms, colorectal cancer risk, and metastasis

The human granzyme B protein (GrB), which is encoded by granzyme B gene (GZMB), plays a major role in eliminating cancer cells. Polymorphisms of GZMB gene such as Q55R, P94A, and Y247H have been shown to affect GrB activity and the subsequent cancer risk.

In this study, we examined possible association between GZMB gene polymorphisms and susceptibility to colorectal cancer (CRC). In addition, the contribution of the examined polymorphisms to colorectal cancer metastasis to lymph node and distant organ was investigated.

A total of 50 venous blood samples collected from CRC patients were analyzed to identify the Q55R, P94A, and Y247H polymorphisms. As a control group, 20 healthy subjects were enrolled in the study. The Q55R, P94A, and Y247H polymorphisms were genotyped by polymerase chain reaction and sequencing method.

Data analysis was carried out using the statistical package SPSS version 17 to compute all descriptive statistics. Chi-square and Fisher exact tests (if the expected value in any cell is less than 5) were used to evaluate the genotype distribution and allele frequencies of the studied polymorphism.

The results revealed that the distribution of Q55R, P94A, and Y247H are not significantly different in CRC patients compared to the controls. In addition, no association between Q55R, P94A, and Y247H polymorphisms and its metastasis to lymph node and distant organ was detected.

These results suggest that GZMB Q55R, P94A, and Y247H polymorphisms are not significantly associated with colon cancer incidence, or metastasis to lymph node and distant organ. However, this study was limited by its relatively small sample size; thus, to confirm current findings, a bigger multicenter design study is warranted.