Document Type: Research Articles
Gastroenterohepatology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
Transplant Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
Colorectal Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
Fasa University of Medical Sciences, Fasa, Iran.
Background: Positive and negative co-stimulatory molecules are important factors determining the outcome
of immune responses to the presence of tumors. Since co-stimulatory molecule expression may be affected by gene
polymorphisms, we aimed to investigate associations between variants of PD.1 and ICOS and susceptibility to colon
cancer. Material and methods: ICOS (-693A/G), ICOS (+1720C/T) and PD.1 (-538G/A) gene polymorphisms were
evaluated by the PCR-RFLP method in 76 colon cancer patients and 73 healthy controls. Results: The frequencies
of the GG genotype and the G allele at position -693 of the ICOS gene were significantly higher in the patient group
(P=0.014 and p=0.0002), while the AA genotype was significantly more common in controls (P=0.0016). At position
-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
to those of controls (P=0.016 and P<0.0001), while, frequencies of GTA, ATA and ATG haplotypes were higher in
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
ICOS (-693A/G) gene polymorphisms can be considered as genetic risk factors for the development of colon cancer
among Iranian patients.