No association between genetic polymorphisms in insulin and insulin receptor substrate-1 and prostate cancer

The Role of Polymorphisms in Genes of PI3K/Akt Signaling Pathway on Prostate

Background and Objective: Increasing evidence suggested that polymorphisms in genes of PI3K/Akt pathway were closely related to prostate cancer (PCa) risk. Nevertheless, these results are controversial and inconclusive. Here, we conducted a comprehensive updated meta-analysis and systematic review to precisely illustrate the association between polymorphisms in genes of PI3K/Akt signaling pathway and PCa risk.

Materials and Methods: The gene set of PI3K/Akt pathway was referenced from the Kyoto Encyclopedia of Genes and Genomes (KEGG) website. Relevant studies were identified by the systematically researching on PubMed, Web of Science and Google Scholar databases up to October 1, 2017. The odds ratios (ORs) with a corresponding 95% confidential intervals (95%CIs) were applied to test their associations. All the analyses were conducted by using Stata 12.0 (Stata Corporation, USA).

Results: Finally, 38 articles comprising 62 case-control studies were enrolled for 13 polymorphisms in genes of PI3K/Akt pathway. However, overall results failed to present a positive association between polymorphisms in genes of PI3K/Akt pathway and PCa risk. Nevertheless, in the subgroup analysis by ethnicity, we identified that IL-6-rs1800795 polymorphism was associated with an increased risk of PCa for Caucasian individuals in dominant model (MM + MW vs. WW: OR = 1.245, 95%CI = 1.176-1.318, P < 0.001).

Conclusion: Our work suggests that polymorphisms in genes of PI3K/Akt Signaling Pathway are not risk factor for PCa. Further well-designed studies with larger samples and precise designs are demanded to corroborate our findings.

Association between insulin receptor substrate 1 Gly972Arg polymorphism and cancer risk

Epidemiological studies investigating the association between the insulin receptor substrate 1 (IRS1) gene Gly972Arg (rs1801278) polymorphism and various carcinomas risk reported conflicting results. Thus, a systemic review and meta-analysis of published studies were performed to assess the possible association. A comprehensive search was conducted to identify all eligible studies of IRS1 Gly972Arg polymorphism and cancer risk. Odds ratios (ORs) and 95 % confidence intervals (CIs) were used to assess the strength of the associations. A total of 16 independent studies, including 11,776 cases and 11,654 controls, were identified. When all studies were pooled, we found a significant association between IRS1 Gly972Arg polymorphism and increased cancer risk under dominant model (OR = 1.16, 95 %CI = 1.04-1.30, P = 0.007) and allelic model (OR = 1.16, 95 %CI = 1.02-1.30, P = 0.02). In subgroup analysis based on cancer type, increased cancer risk was found in ovarian cancer (dominant: OR = 1.55, 95 %CI = 1.17-2.05, P = 0.002; allelic: OR = 1.55, 95 %CI = 1.19-2.01, P = 0.001), breast cancer (allelic: OR = 1.12, 95 %CI = 1.00-1.26, P = 0.05), and other cancers (allelic: OR = 1.31, 95 %CI = 1.00-1.71, P = 0.05). When stratified by study types, significant associations were observed in both cohort studies (dominant: OR = 1.25, 95 %CI = 1.06-1.47, P = 0.007; allelic: OR = 1.25, 95 %CI = 1.07-1.46, P = 0.005) and case-control studies (dominant: OR = 1.15, 95 %CI = 1.01-1.31, P = 0.04). In the subgroup analyses by ethnicity, significantly increased cancer risk was suggested among both Caucasians (dominant: OR = 1.13, 95 %CI = 1.02-1.26, P = 0.02; allelic: OR = 1.13, 95 %CI = 1.03-1.25, P = 0.01) and mixed population (dominant: OR = 1.22, 95 %CI = 1.01-1.46, P = 0.04). Our investigations demonstrate that IRS1 Gly972Arg polymorphism was associated with an increased risk of cancer, and additional well-designed studies are warranted to validate these findings.

Insulin receptor H1085H C>T and insulin receptor substrate 1 G972R polymorphisms and prostate cancer risk: a pilot study

BACKGROUND

In recent years, numerous studies have focused their attention on genes that are part of the insulin/insulin-like growth factor 1 signaling pathway, such as the insulin receptor (INSR) and the insulin receptor substrate 1 (IRS1) genes.

AIM

We aimed to examine the association of INSR H1085H C>T and IRS1 G972R polymorphisms with prostate cancer (PC). We also aimed to examine possible association with cancer severity assessed by Gleason score.

MATERIALS AND METHODS

We have studied 180 consecutive patients referred for PC screening. The genotyping of two polymorphisms (INSR H1085H C>T and IRS1 G972R) was performed by the polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

There was no difference in genotype (p=0.794) or allelic (p=0.621) frequency of the IRS1 G972R polymorphism between PC (n=119) and control (n=61) groups. However, a significant difference was found in INSR H1085H C>T polymorphism genotype and allelic distribution. Carriers of the polymorphic allele (C/T+T/T) were more frequent in control group patients than in the PC group (54.10% vs. 37.82%; p=0.040; odds ratio [95% confidence interval]=0.52 [0.28-0.96]). The IRS1 and INSR polymorphism distribution did not differ in subgroups according to Gleason score.

CONCLUSION

INSR H1085H C>T polymorphism seems to be associated with PC risk, whereas IRS1 G972R is not. However, because of the limited power of this study, there is a possibility that some modest effects of the IRS1 G972R polymorphism on PC risk went undetected. Neither polymorphism is associated with the degree of PC malignancy.

No association between a polymorphic variant of the IRS-1 gene and prostate cancer risk

OBJECTIVE

Insulin receptor substrate-1 (IRS-1) acts as a docking protein between the insulin-like growth factor-1 (IGF-1) receptor and intracellular signaling molecules in the IGF-1 signaling pathway. Accumulating data support a role of IGF-1 in prostate carcinogenesis. We assessed the influence of the most common IRS-1 gene polymorphism (Gly972Arg) on prostate cancer risk, alone and in combination with IGF-1 and other components in the IGF-1 signaling pathway.

MATERIALS AND METHODS

In a nested case-control study within the Physicians' Health Study, the IRS-1 polymorphism was assayed from prospectively collected samples from 564 incident prostate cancer cases and 758 controls matched on age and smoking. We calculated relative risks (RR) and 95% confidence intervals (CI) using conditional logistic regression.

RESULTS

Among the controls, 0.8% were homozygous (AA) and 12% were heterozygous (GA) for the polymorphic allele. There was no association between carriage of the A allele and total prostate cancer risk (RR = 1.1 95% CI = 0.8-1.5), advanced disease (stage C or D or lethal prostate cancer, RR = 1.3 95% CI = 0.8-2.3), or plasma IGF-1 levels. We explored possible interactions with body mass index and components in the IGF-1 pathway including IGFBP3, PI3k, and PTEN but none of these factors influenced the relation between IRS-1 genotype and prostate cancer risk.

CONCLUSIONS

Our data do not support an association between carriage of the variant IRS-1 gene and prostate cancer risk.