Association Between CA Repeat Polymorphism In IGF1 Gene Promoter And Colorectal Cancer Risk And Pathological Characteristics

Insulin-like growth factor 1(IGF1)is implicated in the growth of normal cell.It has been reported that IGF1 has a mitogenic and anti-apoptotic effect on colorectal cancer cells.However,results of studies on the association between cytosine-adenine(CA)repeat polymorphism in IGF1 gene promoter and colorectal cancer(CRC)risk are inconsistent.This study aims to evaluate the association between CA repeat polymorphism and CRC risk,as well as its relationship with the clinicopathological characteristics of CRC and circulating IGF1 level in a native Chinese population.Objectives To investigate the correlation between CA repeat polymorphism and CRC risk,the association of CA repeat polymorphism with the clinicopathological characteristics of CRC and circulating IGF1 level respectively.Contents and Methods There were 734 participants who were Han Chinese in this case-control study,including 367 CRC cases and 367 age-and sex-matched controls.The data of clinicopathological characteristics of CRC was collected.Circulating IGF1 level was measured by chemiluminescence assay.CA repeat polymorphism was genotyped by PCR and fragment analysis.Odds ratio(OR)and 95% confidence interval(CI)were evaluated by unconditional logistic regression analysis.Results1.<38 CA repeats was associated with decreased CRC risk after adjusting for age and sex(37 versus 38 CA repeats:OR=0.45;95%CI=0.26-0.78),especially in males.(CA)18/19 genotype showed approximately half reduced CRC risk comparing to(CA)19/19 genotype(OR=0.46;95%CI=0.25-0.85).2.There was a significant association between the sum of CA repeats and degree of differentiation of CRC(P=0.044).3.Circulating level of IGF1 in cases was significantly higher than that in controls(P=0.002),particularly in males.In addition,we observed a trend that circulating level of IGF1 in individuals with CA?38 repeats was lower than that inindividuals with CA>38 repeats with a borderline statistically significance in overall and males.Conclusions Results of this study support the possible role of CA repeat polymorphism in CRC risk.