IGF1 htSNPs in relation to IGF-1 levels in young women from high-risk breast cancer families: implications for early-onset breast cancer

The G allele of the IGF1 rs2162679 SNP is a potential protective factor for any myopia: Updated systematic review and meta-analysis

BACKGROUND

The insulin-like growth factor 1 (IGF1) gene is located within the myopia-associated MYP3 interval, which suggests it may play an important role in the progression of myopia. However, the association between IGF1 SNPs and any myopia is rarely reported.

METHODS

A comprehensive literature search was conducted on studies published up to July 22, 2021 in PubMed, EMBASE, CBM, COCHRANE, CNKI, WANFANG and VIP databases. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for single-nucleotide polymorphisms (SNPs) that have been evaluated in at least three studies.

RESULTS

Nine studies involving 4596 subjects with any myopia and 4950 controls examined 25 SNPs in IGF1 gene, among which seven SNPs were included in this meta-analysis. Significant associations were not found in any genetic models between rs6214, rs12423791, rs5742632, rs10860862, rs5742629 and any myopia. Rs2162679 was suggestively associated with any myopia in the codominant model (GA vs. AA: OR = 0.87, 95% CI: 0.76-1.00) and the dominant model (GG+GA vs. AA: OR = 0.88, 95% CI = 0.78-1.00).

CONCLUSION

Meta-analysis of updated data reveals that the G allele of the IGF1 rs2162679 SNP is a potential protective factor for any myopia, which is worth further researches.

Current smoking is associated with a larger waist circumference and a more androgenic profile in young healthy women from high-risk breast cancer families

The purpose was to elucidate the interplay between current smoking, anthropometric measurements, and endogenous hormone levels in women ≤ 40 years. Questionnaires on lifestyle and reproductive factors were completed by 269 healthy women from high-risk breast cancer families between 1996 and 2006 in Sweden. Blood samples for analyses of plasma testosterone, estradiol, androstenedione, sex hormone-binding globulin, and body measurements were obtained 5–10 days before predicted onset of the next menstrual period. Women without smoking status, who were currently breastfeeding, or using hormonal contraception other than combined oral contraceptives (OCs) were excluded (n = 27). Current smokers (n = 57) had larger waist circumference (_adjp = 0.004) and waist-to-hip ratio (WHR) (_adjp = 0.007) than non-smokers (n = 185). In non-OC users, adjusted mean androstenedione levels were higher in current smokers compared with non-smokers (10.3 vs. 8.6 nmol/L; _adjp = 0.0002). While in current OC users estradiol levels were higher in smokers compared with non-smokers (22.5 vs. 17.4 pg/mL; _adjp = 0.012). In multivariable models, WHR was associated with both current smoking (_adjp ≤ 0.016) and higher levels of androstenedione (_adjp = 0.05) or bioavailable testosterone (_adjp = 0.001). Among non-OC users, a more androgenic profile was observed in current smokers compared with non-smokers, but not in current OC users. Irrespective of OC use, current smoking was associated with increased waist circumference.

Interaction of insulin-like growth factor-I and insulin resistance-related genetic variants with lifestyle factors on postmenopausal breast cancer risk

PURPOSE

Genetic variants and traits in metabolic signaling pathways may interact with obesity, physical activity, and exogenous estrogen (E), influencing postmenopausal breast cancer risk, but these inter-related pathways are incompletely understood.

METHODS

We used 75 single-nucleotide polymorphisms (SNPs) in genes related to insulin-like growth factor-I (IGF-I)/insulin resistance (IR) traits and signaling pathways, and data from 1003 postmenopausal women in Women's Health Initiative Observation ancillary studies. Stratifying via obesity and lifestyle modifiers, we assessed the role of IGF-I/IR traits (fasting IGF-I, IGF-binding protein 3, insulin, glucose, and homeostatic model assessment-insulin resistance) in breast cancer risk as a mediator or influencing factor.

RESULTS

Seven SNPs in IGF-I and INS genes were associated with breast cancer risk. These associations differed between non-obese/active and obese/inactive women and between exogenous E non-users and users. The mediation effects of IGF-I/IR traits on the relationship between these SNPs and cancer differed between strata, but only roughly 35% of the cancer risk due to the SNPs was mediated by traits. Similarly, carriers of 20 SNPs in PIK3R1, AKT1/2, and MAPK1 genes (signaling pathways-genetic variants) had different associations with breast cancer between strata, and the proportion of the SNP-cancer relationship explained by traits varied 45-50% between the strata.

CONCLUSIONS

Our findings suggest that IGF-I/IR genetic variants interact with obesity and lifestyle factors, altering cancer risk partially through pathways other than IGF-I/IR traits. Unraveling gene-phenotype-lifestyle interactions will provide data on potential genetic targets in clinical trials for cancer prevention and intervention strategies to reduce breast cancer risk.

Maternal IGF1 and IGF1R polymorphisms and the risk of spontaneous preterm birth

BACKGROUND

The insulin-like growth factor (IGF) pathway was involved in the occurrence of spontaneous preterm birth (SPTB), but little is known regarding the relationship between genetic variations in IGF pathway and the risk of SPTB. We aimed to investigate the associations of IGF1 rs972936 and IGF1 receptor (IGF1R) rs2229765 polymorphisms with SPTB risk in a Chinese population.

METHOD

A total of 114 cases of SPTB and 250 controls of term delivery were included from Guangzhou Women and Children's Medical Center, China. The odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) were calculated using multivariate logistic regression.

RESULTS

We found that the GA and GA/AA genotypes of IGF1 rs972936 were associated with an increased risk of SPTB, and the adjusted ORs (95% CI) were 1.74 (1.01-3.02) and 1.75 (1.04-2.93) respectively. Women carrying GA and GA/AA genotypes of IGF1R rs2229765 had a reduced risk compared to those with the GG genotype (0.60 [0.37-0.98] and 0.64 [0.40-1.00] respectively). There were significant interactions between IGF1 rs972936 and GDM status (P for interaction=.02), as well as between IGF1R rs2229765 and pre-pregnancy BMI (P for interaction <.001) on the risk of SPTB.

CONCLUSION

Our findings suggest that polymorphisms of IGF1 rs972936 and IGF1R rs2229765 were associated with the risk of SPTB in Chinese pregnant women and these effects depend on the maternal metabolic status.

Insulin-like Growth Factor 1 gene polymorphism and breast cancer risk

Insulin-like Growth Factor-1 (IGF-1) gene polymorphism has been associated with an increased risk for breast cancer. IGF-1 is a key regulator of proliferation, cell differentiation and apoptosis. It has important mitogenic and anti-apoptotic activities in normal cells and in breast cancer cells, acting synergistically with estrogen to increase neoplastic cell proliferation. This review aims to present the recent finds of IGF-1 gene polymorphism and its relationship with the risk of breast cancer through following the polymorphic dinucleotide repeat cytosine-adenine (CA) and single nucleotide polymorphisms (SNPs) by searching in the PubMed database publications focused studies published from 2010 to 2015 related to IGF-1 gene polymorphism and breast cancer risk. A growing number of studies support an association between IGF-1 gene polymorphism and breast cancer risk with conflicting results, nevertheless elucidation of the patterns of IGF-1 gene expression may permit characterization of women at high-risk for breast cancer, as well as the development of strategies for early diagnosis and efficient treatment against the disease.

Insulin-like growth factor (IGF) axis in cancerogenesis

Determination of the role of insulin-like growth factor (IGF) family components in carcinogenesis of several human tumors is based on numerous epidemiological and pre-clinical studies, experiments in vivo and in vitro and on attempts at application of drugs affecting the IGF axis. Investigative hypotheses in original studies were based on biological functions manifested by the entire family of IGF (ligands, receptors, linking proteins, adaptor molecules). In the context of carcinogenesis the most important functions of IGF family involve intensification of proliferation and inhibition of cell apoptosis and effect on cell transformation through synthesis of several regulatory proteins. IGF axis controls survival and influences on metastases of cells. Interactions of IGF axis components may be of a direct or indirect nature. The direct effects are linked to activation of PI3K/Akt signaling pathway, in which the initiating role is first of all played by IGF-1 and IGF-1R. Activity of this signaling pathway leads to an increased mitogenesis, cell cycle progression, and protection against different apoptotic stresses. Indirect effects of the axis depend on interactions between IGF and other molecules important for cancer etiology (e.g. sex hormones, products of suppressor genes, viruses, and other GFs) and the style of life (nutrition, physical activity). From the clinical point of view, components of IGF system are first of all considered as diagnostic serous and/or tissue biomarkers of a given cancer, prognostic factors and attractive target of modern anti-tumor therapies. Several mechanisms in which IGF system components act in the process of carcinogenesis need to be clarified, mainly due to multifactorial etiology of the neoplasms. Pin-pointing of the role played in carcinogenesis by any single signaling pathway remains particularly difficult. The aim of this review is to summarize the current data of several epidemiological studies, experiments in vitro and on animal models, to increase our understanding of the complex role of IGF family components in the most common human cancers.

Association of Insulin-Like Growth Factor-1 Gene Polymorphisms with Different Types of Myopia in Egyptian Patients

AIMS

To investigate the effect of the insulin-like growth factor-1 (IGF-1) gene's rs6214 and rs5742632 polymorphisms on IGF-1 expression levels and their association with different types of myopia in Egyptian patients.

METHODS

A case-control format was used that included 272 patients with myopia and 136 controls. The IGF-1 gene rs6214 and rs5742632 polymorphisms were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analyses. IGF-1 levels were measured by an enzyme-linked immunosorbent assay.

RESULTS

In patients with high-grade myopia, the frequencies of the IGF-1 rs6214 GA and AA genotypes, and the A allele were significantly increased compared to the control group: 41.9% vs. 33.8%, 17.7% vs. 8.9%, and 38.9% vs. 25.7%, respectively. Subjects with the GA and AA genotypes and carriers of A allele were significantly more likely to have high-grade myopia: odds ratios (OR) = 1.75, 95% confidence interval (CI) = 1.03-2.9, and p = 0.03; OR = 2.8, 95% CI = 1.3-6.0, and p = 0.003; and OR = 1.8, 95% CI = 1.25-2.61, and p = 0.001, respectively. A nonsignificant association of the IGF-1 gene rs5742632 polymorphism with the two myopia groups was also observed. The IGF-1 levels were significantly increased in patients with high-grade myopia and simple myopia compared to the control group (p < 0.05). In addition, our results showed a nonsignificant association of the IGF-1 (rs6214-rs5742632) haplotype with either simple myopia or high-grade myopia.

CONCLUSIONS

We found a significant association of the IGF-1 gene rs6214 polymorphism in Egyptian patients with simple myopia and high-grade myopia. IGF-1 levels were significantly increased in relation to the IGF-1 rs6214 genotypes, while a nonsignificant association was found between IGF-1 level and the IGF-1 (rs5742632) genotypes.

The role of the insulin-like growth factor-1 system in breast cancer

IGF-1 is a potent mitogen of major importance in the mammary gland. IGF-1 binding to the cognate receptor, IGF-1R, triggers a signaling cascade leading to proliferative and anti-apoptotic events. Although many of the relevant molecular pathways and intracellular cascades remain to be elucidated, a growing body of evidence points to the important role of the IGF-1 system in breast cancer development, progression and metastasis. IGF-1 is a point of convergence for major signaling pathways implicated in breast cancer growth. In this review, we provide an overview and concise update on the function and regulation of IGF-1 as well as the role it plays in breast malignancies.

Assessment of age-related changes in heritability and IGF-1 gene effect on circulating IGF-1 levels

It is well established that insulin-like growth factor 1 (IGF-1) circulating levels correlate with age and that heritability and influence of IGF-1 gene variation on IGF-1 levels also well-known. However, the influence of age on the genetic factors determining IGF-1 levels is not clear. In this study, we compared heritability estimates between younger (<52 years) and older (>52 years) twins and tested: (a) whether single nucleotide polymorphisms (SNPs) lying within 100 kbp of the IGF-1 gene are also associated with IGF-1 variation and (b) whether associated SNPs show interaction with age on IGF-1 levels. To achieve these aims, we measured plasma levels of IGF-1 and genotyped 18 SNPs with minor allele frequency >0.1 in a large sample, 4,471 UK female twins. Heritability explained 42 % of IGF-1 variation adjusted for age and in unadjusted sample was independent of age. Ten SNPs in four haploblocks showed significant association with IGF-1 levels, with p = 0.01-0.0005. The most distal SNP was located up to 90 kbp from the IGF-1 gene. When their age-dependent effects were examined, one SNP, rs855203, showed significant (p = 0.0009) age-dependent interaction effect on IGF-1 levels variation. This is the first study to test the age × genotype interaction in IGF-1 levels. The genomic region marked by rs855203 may consequently be of significance for further molecular and pharmacogenetic research, in particular in advanced age.

IGF-1 and BRCA1 signalling pathways in familial cancer

The insulin-like growth factor (IGF) system has a direct effect on cellular proliferation and survival, and interacts with genetic and environmental factors implicated in causing cancer. Experimental, clinical, and epidemiological evidence show that the IGF signalling pathways are important mediators in the biochemical and molecular chain of events that lead from a phenotypically normal cell to one harbouring neoplastic traits. BRCA1 and BRCA2 have an important role in the development of hereditary and sporadic breast and ovarian cancer. Recent evidence suggests that risk of cancer conferred by BRCA mutations can be modified by genetic and environmental factors, including ambient concentrations of IGF-1 and polymorphisms in IGF system components. This Review addresses interactions between the IGF and BRCA1 signalling pathways, and emphasises the convergence of IGF-1-mediated cell survival, proliferative pathways, and BRCA1-mediated tumour protective pathways. Understanding the complex interactions between these signalling pathways might improve our understanding of basic molecular oncology processes and help to identify new molecular targets, predictive biomarkers, and approaches for optimising cancer therapies.

Insulin resistance and cancer: the role of insulin and IGFs

Insulin, IGF1, and IGF2 are the most studied insulin-like peptides (ILPs). These are evolutionary conserved factors well known as key regulators of energy metabolism and growth, with crucial roles in insulin resistance-related metabolic disorders such as obesity, diseases like type 2 diabetes mellitus, as well as associated immune deregulations. A growing body of evidence suggests that insulin and IGF1 receptors mediate their effects on regulating cell proliferation, differentiation, apoptosis, glucose transport, and energy metabolism by signaling downstream through insulin receptor substrate molecules and thus play a pivotal role in cell fate determination. Despite the emerging evidence from epidemiological studies on the possible relationship between insulin resistance and cancer, our understanding on the cellular and molecular mechanisms that might account for this relationship remains incompletely understood. The involvement of IGFs in carcinogenesis is attributed to their role in linking high energy intake, increased cell proliferation, and suppression of apoptosis to cancer risks, which has been proposed as the key mechanism bridging insulin resistance and cancer. The present review summarizes and discusses evidence highlighting recent advances in our understanding on the role of ILPs as the link between insulin resistance and cancer and between immune deregulation and cancer in obesity, as well as those areas where there remains a paucity of data. It is anticipated that issues discussed in this paper will also recover new therapeutic targets that can assist in diagnostic screening and novel approaches to controlling tumor development.

Polymorphisms of IGFI contribute to the development of ischemic stroke

Insulin-like growth factor 1 (IFG1) is neuroprotective in animal models of focal brain ischemia and correlates with ischemic stroke (IS) outcome in the elderly. In this study, we investigated whether single nucleotide polymorphisms (SNPs) of the IFG1 gene are associated with the development and clinical features of IS in a Korean population. A total of 119 patients with IS and 289 control subjects were recruited. Stroke patients were classified into subgroups according to the scores of the National Institutes of Health Stroke Survey (NIHSS; <6 and ≥6) and the Modified Barthel Index (MBI; <60 and ≥60). Among the SNPs of the IFG1 gene, five SNPs were selected and analyzed by direct sequencing: rs2162679 (intron), rs2195239 (intron), rs978458 (intron), rs1520220 (intron) and rs6214 (3' untranslated region; 3'UTR). Multiple logistic regression models were conducted to analyze genetic data. SNPStats, SNPAnalyzer Pro and Helixtree programs were used to calculate odds ratios (ORs), 95% confidence intervals (CIs) and p-values. Two SNPs, rs2162679 and rs6214, were associated with the development of IS. After Bonferroni correction (p(c)), the A and G alleles of rs2162679 and rs6214 had significant differences between patients with IS and the controls [rs2162679, OR (95% CI) = 1.64 (1.17-2.31), p=0.004, p(c)=0.02; rs6214, OR (95% CI) = 1.52 (1.12-2.07), p=0.007, p(c)=0.035], respectively. However, the five selected SNPs were not related to the NIHSS and MBI scores. These results suggest that IGF1 may be associated with the development of IS.