HLA-Cw polypmorphism and killer cell immunoglobulin-like receptor (KIR) gene analysis in Korean colorectal cancer patients

Purpose: Natural killer cells (NK cells) play important roles in protecting the patient from the early development of cancers, and are activated or inhibited by killer cell immunoglobulin-like receptors (KIR), which bind to HLA class I. In the present study, we investigated the KIR genotype of Korean colorectal cancer patients. Methods: DNA samples were extracted from peripheral blood cell samples taken from Korean colorectal cancer patients and a control group. KIR genes were amplified using PCR-SSP methods, and HLA-Cw genes were characterized using PCR methods. The results were analyzed to assess the difference between colorectal cancer patients and the normal control group. Results: In the present study, the frequency of KIR2DS5 (33.2% vs. 20.8%, p-value<0.007) was higher in the colorectal cancer group, and in the rectal cancer subgroup, the frequencies of KIR3DL1 (93.2%, vs. 98.1%, p-value<0.05), KIR2DS2 (7.8% vs. 19.5%, p-value<0.01), and KIR2DS4 (93.2% vs. 98.1%, p-value<0.05) were lower significantly. The frequencies of HLA-Cw6 (9.1% vs. 15.7%, p-value<0.05) and HLA-Cw7 (17.4% vs. 27.7%, p-value<0.02) were lower in the colorectal cancer group. Of the patients with HLA-C1 homozygote, the frequency of KIR2DS2 was decreased significantly (5.8% vs. 14.5%, p-value<0.004). Conclusions: The frequency of KIR2DS5 is higher in Korean colorectal cancer patients, and in the rectal cancer subgroup, the frequencies of KIR3DL1, KIR2DS2 and KIR2DS4 are lower. Among the patients with HLA-C1 homozygote, the frequency of KIR2DS2 is decreased. Therefore, KIR2DS2 in presence of its ligand (HLA-C1 group) may have a protective effect against colorectal cancer.