Associations of ICOS and PD.1 Gene Variants with Colon Cancer Risk in The Iranian Population

Abstract

Background: Positive and negative co-stimulatory molecules are important factors determining the outcome<br />of immune responses to the presence of tumors. Since co-stimulatory molecule expression may be affected by gene<br />polymorphisms, we aimed to investigate associations between variants of PD.1 and ICOS and susceptibility to colon<br />cancer. Material and methods: ICOS (-693A/G), ICOS (+1720C/T) and PD.1 (-538G/A) gene polymorphisms were<br />evaluated by the PCR-RFLP method in 76 colon cancer patients and 73 healthy controls. Results: The frequencies<br />of the GG genotype and the G allele at position -693 of the ICOS gene were significantly higher in the patient group<br />(P=0.014 and p=0.0002), while the AA genotype was significantly more common in controls (P=0.0016). At position<br />-538 of PD.1, GG genotype and G allele frequencies were higher in the patient group (PAA and also AG genotypes significantly predominated in controls (Pand alleles of ICOS at position +1720. Frequencies of GCG and GTG haplotypes were higher in patients compared<br />to those of controls (P=0.016 and P<0.0001), while, frequencies of GTA, ATA and ATG haplotypes were higher in<br />controls (P=0.0017, Ppatients compared to controls (P=0.0147 and P=0.0071). Conclusion: Our study clarified that PD.1 (-538G/A) and<br />ICOS (-693A/G) gene polymorphisms can be considered as genetic risk factors for the development of colon cancer<br />among Iranian patients.