Promoter −202 A/C polymorphism of insulin-like growth factor binding protein-3 gene and non-small cell lung cancer risk

Association between acromegaly and a single nucleotide polymorphism (rs2854744) in the IGFBP3 gene

Background

It has been reported that the single nucleotide polymorphism (SNP) rs2854744 at the − 202 locus of insulin-like growth factor binding protein-3 (IGFBP3) is associated with serum levels and a number of malignancies. However, the effect of IGFBP3 gene polymorphism on acromegaly is less clear. Therefore, in the current study, we aimed to investigate whether the −202A/C polymorphism of IGFBP3 constitutes a risk factor for acromegaly.

Methods

The study included 102 acromegalic patients and 143 control subjects in Beijing Tiantan Hospital. The genotyping of IGFBP3 was carried out using the MassARRAY method. Serum IGFBP3 concentrations were also determined. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to evaluate the associations of genetic polymorphisms with the development of acromegaly and its different subtypes.

Results

The study revealed that the C allele of rs2854744 was associated with a reduced risk of acromegaly (OR 0.594, 95% CI 0.388–0.909), as well as with the female (OR 0.385, 95% CI 0.206–0.72), macroadenoma (OR 0.557, 95% CI 0.347–0.893) and monotherapy (OR 0.512, 95% CI 0.316–0.828) subgroups under the additive model. A higher serum IGFBP3 level was observed in patients with the AA genotype, but this difference was not significant (P = 0.331).

Conclusion

This study is one of the first to show that the IGFBP3 polymorphism may have an influence on serum levels and that the C allele of rs2854744 is associated with a reduced risk of acromegaly. This correlation was more prominent in females, those with large tumours and those treated with monotherapy in a Chinese population. Genetic polymorphism of IGFBP3 may be involved in the development of acromegaly.

Influence of The -202 A/C insulin-like growth factor-binding protein-3 promoter polymorphism on individual variation in height in Korean girls

PURPOSE

The most common single nucleotide polymorphism in the IGFBP3 promoter region occurs at position -202. This polymorphic variation occurs frequently and may influence growth hormone responsiveness and somatic growth. However, the effects of IGFBP3 promoter polymorphism on growth in children are unknown.

METHODS

Restriction fragment length polymorphism-based genotyping of the -202 single nucleotide polymorphism was performed in 146 Korean girls aged between 15 and 16 years, who were selected randomly from the Seoul School Health Promotion Center. The participants were divided into 3 groups (tall, medium, and short) according to the height percentile established from normal reference values for Korean children. The serum levels of insulin-like growth factor I (IGF-I) and IGF-binding protein-3 (IGFBP-3) were then compared according to genotype.

RESULTS

The genotype distribution in the participants was 79 AA (54.1%), 60 AC (41.1%), and 7 CC (4.8%). The C allele frequency at the -202 IGFBP3 position was 25.4% in this group. The mean serum IGFBP-3 concentration in girls with the AA genotype was higher than that in girls with the AC genotype in the medium (P=0.047) and short (P=0.035) groups, respectively. There was no difference in the IGF-I to IGFBP-3 molar ratio between the AA and AC genotype groups (P=0.161).

CONCLUSION

In conclusion, the -202 polymorphism in the IGFBP3 promoter region is assumed to affect the serum concentration of IGFBP-3 in children as well as in adults. However, it is unclear whether this affects physical development according to the concentration of IGFBP-3.

Role of IGF1R in Breast Cancer Subtypes, Stemness, and Lineage Differentiation

Insulin-like growth factor (IGF) signaling is fundamental for growth and survival. A large body of evidence (laboratory, epidemiological, and clinical) implicates the exploitation of this pathway in cancer. Up to 50% of breast tumors express the activated form of the type 1 insulin-like growth factor receptor (IGF1R). Breast cancers are categorized into subtypes based upon hormone and ERRB2 receptor expression and/or gene expression profiling. Even though IGF1R influences tumorigenic phenotypes and drug resistance across all breast cancer subtypes, it has specific expression and function in each. In some subtypes, IGF1R levels correlate with a favorable prognosis, while in others it is associated with recurrence and poor prognosis, suggesting different actions based upon cellular and molecular contexts. In this review, we examine IGF1R expression and function as it relates to breast cancer subtype and therapy-acquired resistance. Additionally, we discuss the role of IGF1R in stem cell maintenance and lineage differentiation and how these cell fate influences may alter the differentiation potential and cellular composition of breast tumors.

Functional polymorphisms in the insulin-like binding protein-3 gene may modulate susceptibility to differentiated thyroid carcinoma in Caucasian Americans

The insulin-like growth factor (IGF) pathway is believed to play a pivotal role in thyroid carcinogenesis. Polymorphisms of IGF-1 and IGF binding protein-3 (IGFBP-3) have been associated with modulation of risk for the emergence of assorted common malignancies, but studies of the influence of such polymorphisms on risk of differentiated thyroid carcinoma (DTC) are lacking. In a case-control study of 173 DTC patients, 101 patients with benign thyroid disease, and 401 controls, an unconditional logistical regression model adjusted for age and sex was applied to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for the associations between polymorphisms of IGF-1 and IGFBP-3 and DTC risk. IGFBP-3 rs2132572 GA/AA genotypes were associated with a decreased risk of DTC (adjusted OR = 0.6, 95% CI: 0.4-0.9), particularly multifocal DTC (adjusted OR = 0.3, 95% CI: 0.1-0.7). The association with DTC was more evident in subjects with a first-degree family history of cancer (adjusted OR = 0.4, 95% CI: 0.2-0.7, P(interaction)  = 0.013) and non-drinkers (adjusted OR = 0.4, 95% CI: 0.2-0.7, P(interaction)  = 0.028). A four single nucleotide polymorphism haplotype of IGFBP-3 was associated with a decreased risk of DTC (adjusted OR = 0.7, 95% CI: 0.5-1.0, P = 0.030). Our study suggests that polymorphic IGFBP-3 may be involved in susceptibility to DTC.

Association between insulin-like growth factor binding protein-3 promoter polymorphism of -1590 C>A and lung cancer susceptibility in a Chinese Han population

Recent studies have identified a negative correlation between serum levels of insulin-like growth factor binding protein-3 (IGFBP-3) and the risk of lung cancer. In this study, polymorphisms present at the -1590 site of the IGFBP-3 promoter were evaluated in relation to lung cancer risk in a Chinese Han population. A total of 248 nonsmall cell lung cancer (NSCLC) cases and 29 small cell lung cancer cases were compared with 252 matched, healthy controls. Polymerase chain reaction-based restriction fragment length polymorphism assays were used to detect polymorphisms present. The A/A genotype and an A allele were both associated with an increased risk of NSCLC after being adjusted for age and gender (adjusted odds ratio = 2.296, 95% confidence interval = 1.133-4.655; and adjusted odds ratio = 1.390, 95% confidence interval = 1.042-1.854, respectively). In conclusion, the A/A genotype and A allele of the IGFBP-3 promoter -1590 site may represent a genetic risk factor for NSCLC, with the A/A genotype being associated with a higher risk for squamous cell carcinoma than adenocarcinoma.

Functional modulation of IGF-binding protein-3 expression in melanoma

IGF-binding protein-3 (IGFBP3) is a member of the IGFBP family, which regulates mitogenic and antiapoptotic effects of IGFs. In this report we evaluated the role of IGFBP3 in melanoma. Quantitative real-time PCR (qRT-PCR), western blot, and ELISA analyses indicated a significant downregulation of IGFBP3 expression in melanoma cell lines as compared with a normal melanocyte cell line. Melanoma cell lines treated with the demethylating agent 5-AZA-2'-deoxycytidine reexpressed IGFBP3 at the mRNA and protein levels. Chromatin immunoprecipitation assays revealed enrichment of acetylated histones H3 and H4, and H3 di- and tri-methylated lysine 4 on the unmethylated IGFBP3 promoter. The IGFBP3 promoter region was highly methylated in human melanoma samples as compared with normal nevi. Overexpression of IGFBP3 in melanoma cells in vitro suppressed tumor cell survival, induced apoptosis, reduced colony formation and invasion, and induced expression of the proapoptotic genes p21, PUMA, and BAX. IGFBP3 overexpression also resulted in cleavage of caspase 3 and reduced expression of phosphorylated AKT. Stable overexpression of IGFBP3 suppressed tumor cell growth in vivo. Our study results indicate that silencing of IGFBP3 in melanoma is due to the methylation of its promoter, and that overexpression of IGFBP3 induces apoptosis and suppresses cell survival and growth.

Genetic and epigenetic variability in the gene for IGFBP-3 (IGFBP3): correlation with serum IGFBP-3 levels and growth in short children born small for gestational age

CONTEXT

IGF-I and IGFBP-3 play a central role in fetal and postnatal growth and levels are low in short SGA children. The -202 A/C and -185 C/T SNPs are located near elements involved in directing IGFBP3 promoter activity and expression. Changes in promoter CpG methylation status affect transcription factor binding and transcriptional activation of IGFBP3 in vitro.

OBJECTIVE

To assess the relationship between IGFBP3 promoter SNPs, IGFBP-3 levels, spontaneous growth and growth response to GH treatment in short prepubertal SGA children. To assess promoter methylation status in a subgroup of short SGA subjects and controls.

PATIENTS

292 Short prepubertal SGA children, 39 short young SGA adults and 85 young adults with normal stature.

INTERVENTION

Short prepubertal SGA children received GH 1mg/m(2)/day.

OUTCOME MEASURES

Fasting levels of IGF-I and IGFBP-3, baseline and delta height SDS.

RESULTS

At baseline, IGFBP-3 levels were highest in SGA children with -202 AA genotype and lower in children with 1 or 2 copies of the C-allele (P<0.001). Children with C(-202)/C(-185) haplotype, compared to children with A(-202)/C(-185) haplotype, had lower IGFBP-3 levels (P=0.003) and were shorter (P=0.03). During GH treatment, children with C(-202)/C(-185) haplotype showed a significantly greater increase in IGFBP-3 SDS and in height SDS than children with A(-202)/C(-185) haplotype, resulting in similar IGFBP-3 levels and similar height SDS after 12 months of GH treatment. CpG methylation patterns showed a trend towards more methylation of CpGs involved in transcription factor binding in short young SGA adults compared to controls.

CONCLUSION

Polymorphic variation in the IGFBP3 promoter region is correlated with IGFBP-3 levels, spontaneous growth and response to GH treatment in short SGA children.

IGF and insulin receptor signaling in breast cancer

Major molecular abnormalities in breast cancer include the deregulation of several components of the IGF system. It is well recognized that the epithelial breast cancer cells commonly overexpress the IGF-I receptor while IGF-II is expressed by the tumor stroma. In view to the fact that the IGF-IR has mitogenic, pro-invasive and anti-apoptotic effects and mediates resistance to a variety of anti-cancer therapies, breast cancer is expected to be a candidate to therapeutic approaches aimed to inhibit the IGF-IR. However, there is increasing awareness that IGF system in cancer undergoes signal diversification by various mechanisms. One of these mechanisms is the aberrant expression of insulin receptor (IR) isoform A (IR-A), which is a high affinity receptor for both insulin and IGF-II, in breast cancer cells. Moreover, overexpression of both IGF-IR and IR-A in breast cancer cells, leads to overexpression of hybrid IR/IGF-IR receptors (HRs) as well. Upon binding to IGF-II, both IR-A and HRs may activate unique signaling patterns, which predominantly mediate proliferative effects. A better understanding of IGF system signal diversification in breast cancer has important implications for cancer prevention measures, which should include control of insulin resistance and associated hyperinsulinemia. Moreover, in addition to the IGF-IR, both IR-A and HRs should be also considered as molecular targets for anti-cancer therapies.

The emerging role of the insulin-like growth factor pathway as a therapeutic target in cancer

The insulin-like growth factor signaling pathway is important in many human cancers based on data from experimental models as well as epidemiological studies. Important therapies targeted at this pathway have been or are being developed, including monoclonal antibodies to the insulin-like growth factor-I receptor and small molecule inhibitors of the tyrosine kinase function of this receptor. These investigational therapies are now being studied in clinical trials. Emerging data from phase I trials are encouraging regarding the safety of the monoclonal antibodies. In this manuscript, the rationale for targeting the insulin-like growth factor system is reviewed in addition to a summary of the available clinical trial data.

Identification of upstream stimulatory factor binding sites in the human IGFBP3 promoter and potential implication of adjacent single-nucleotide polymorphisms and responsiveness to insulin

The actions of IGFs are regulated at various levels. One mechanism involves binding to IGF-binding protein-3 (IGFBP-3) for transport, thus governing bioavailability. IGFBP3 transcription is modulated by many hormones and agents that stimulate or inhibit growth. We have previously shown in pediatric and adult cohorts a correlation between IGFBP-3 serum levels and two single-nucleotide polymorphisms (SNPs) located within the minimal promoter (-202 A/C and -185 C/T). Functionality of these SNPs was further explored in hepatic adenocarcinoma-derived SK-HEP-1 cells using transient transfections of luciferase constructs driven by different haplotypes of the IGFBP3 promoter. Basal luciferase activity revealed a significant haplotype-dependent transcriptional activity (at nucleotides -202 and -185, AC > CC, P < 0.001; AC > CT, P < 0.001; AC > AT, P < 0.001). Insulin treatment produced a similar haplotype dependence of luciferase activity (AC > CC, P = 0.002; AC > CT, P < 0.001; AC > AT, P = 0.011). However, induction ratios (insulin/control) for CC and AT were significantly higher compared with AC and CT (CC > AC, P = 0.03; CC > CT, P = 0.03; AT > AC, P = 0.03; AT > CT, P = 0.04). Gel retardation assays were used to identify upstream stimulatory factor (USF-1 and USF-2) methylation-dependent binding to E-box motifs located between the SNPs. Mutation of the USF binding site resulted in a significant loss of insulin stimulation of luciferase activity in the transfection assay. Chromatin immunoprecipitation with anti-USF-1/-2 showed an enrichment of IGFBP3 promoter in insulin-treated cells compared with unstimulated cells. Bisulfite sequencing of genomic DNA revealed that CpG methylation in the region of USF binding was haplotype dependent. In summary, we report a methylation-dependent USF binding site influencing the basal and insulin-stimulated transcriptional activity of the IGFBP3 promoter.

Mechanisms of disease: signaling of the insulin-like growth factor 1 receptor pathway--therapeutic perspectives in cancer

The insulin-like growth factor 1 (IGF1) signaling pathway is implicated in the development of cancer. High levels of circulating IGF1 and certain genetic polymorphisms of IGF1 and IGFBP3 are associated with an increased risk of several common cancers. The IGF1 receptor (IGF1R) has been shown to be expressed in a wide range of tumors, and IGF1R signaling is crucial for tumor transformation and the survival of malignant cells. Several monoclonal antibodies and small-molecule inhibitors have been tested in preclinical studies and early-phase clinical studies. IGF1R signaling interferes with numerous growth factors and receptors such as VEGF and EGFR. In the experimental system, IGF1R signaling has been found to correlate with resistance to therapies based on the inhibition of EGFR and HER2. This Review highlights the most relevant studies in this exciting area of research, focusing in particular on the role of IGF1R in resistance to other receptor-targeted therapies for cancer.

Targeting mTOR signaling in lung cancer

Lung cancer is the leading cause of cancer-related mortality in the world, with more than 1 million deaths per year. Over the past years, lung cancer treatment has been based on cytotoxic agents and an improvement in the outcome and quality of life for patients has been observed. However, it has become clear that additional therapeutic strategies are urgently required in order to provide an improved survival benefit for patients. Two major intracellular signaling pathways, the Ras/Raf/extracellular signal-regulated kinase (Erk) and the phosphoinositide 3-kinase (PI3K)/Akt pathways have been extensively studied in neoplasia, including lung cancer. Furthermore, the study of constitutively activated receptor tyrosine kinases (RTKs) and their downstream signaling mediators has opened a promising new field of investigation for lung cancer treatment. Since both the Ras/Raf/Erk and the PI3K/Akt pathways are downstream of a plethora of activated RTKs, they have been extensively studied for the development of novel anti-tumor agents. Moreover, the mammalian target of rapamycin (mTOR) has been identified as a downstream target of the PI3K/Akt pathway. Rapamycin and its derivatives are highly selective and very potent inhibitors of mTOR and initial pre-clinical and clinical studies have reported encouraging results for different tumor types. Nevertheless for lung cancer, this approach has not been successful yet. Here we will review the molecular basis of PI3K/Akt/mTOR signaling in lung cancer and further discuss the therapeutic potential of multi-targeted strategies involving mTOR inhibitors.

Prostate cancer risk in relation to selected genetic polymorphisms in insulin-like growth factor-I, insulin-like growth factor binding protein-3, and insulin-like growth factor-I receptor

We conducted a nested case-control study within a cohort of elderly Americans to examine the role of the insulin-like growth factor (IGF) signaling pathway in prostate cancer etiology. The distribution of genotypes of IGF-I (CA)n, IGF binding protein-3 (IGFBP-3) A-202C, and of the 2-bp deletion and (AGG)n polymorphisms in IGF-I receptor (IGF-IR) was compared between men with prostate cancer (n = 213) and equal number of controls matched on year of blood draw, survival until the date of diagnosis, race, and age. Among controls, the number of CA repeats in IGF-I was not correlated to any appreciable degree with plasma IGF-I concentration, whereas the IGFBP-3 CC genotype was associated with a relatively low level of plasma IGFBP-3. There was no association between prostate cancer risk and the number of CA repeats in IGF-I, IGFBP-3 genotype, or the presence of the 2-bp deletion in IGF-IR. There was a small increased risk among men who did not carry two copies of the (AGG)7 allele of IGF-IR. These results add to the evidence that the number of IGF-I CA repeats is not associated with prostate cancer risk. Our observation that men who do not carry two copies of the IGF-IR (AGG)7 allele are at increased risk of prostate cancer merits further investigation.

Aberrant promoter methylation of insulin-like growth factor binding protein-3 gene in human cancers

Insulin-like growth factor binding protein-3 (IGFBP-3) is postulated to be a mediator of growth suppression signals. Here, we examined the methylation status of IGFBP-3 to correlate to clinicopathological factors in human cancers. The methylation status of IGFBP-3 was determined by bisulfite DNA sequencing and was correlated with expression semi-quantified by real-time RT-PCR to develop a methylation-specific PCR (MSP) assay for IGFBP-3. Using the MSP assay, we examined the methylation status of IGFBP-3 in gastric cancer (GC), colorectal cancer (CRC), breast cancer (BC) and malignant mesothelioma (MM). IGFBP-3 methylation was detected in 6 of 13 (46%) and 16 of 24 (67%) GC cell lines and tumors, respectively; 4 of 8 (50%) and 15 of 26 (58%) CRC cell lines and tumors, respectively; 3 of 11 (27%) and 7 of 39 (18%) BC cell lines and tumors, respectively and 1 of 5 (20%) and 18 of 56 (32%) MM cell lines and tumors, respectively. Interestingly, the methylation status of MM specimens from Japanese patients (75%, 12 out of 16 patients) was significantly higher than those from the USA (15%, 6 out of 40 patients) (p < 0.0001), suggesting the presence of ethnic differences in the IGFBP-3 methylation status. We also found that IGFBP-3 methylation was preferentially present in GCs arising in the lower-third of the stomach (p = 0.079). In summary, our results showed that IGFBP-3 methylation played an important role in the silencing of its expression, suggesting that IGFBP-3 may act as a tumor suppressor gene in several human cancers examined.

The IGF-1 network in lung carcinoma therapeutics

Elucidation of the molecular events that underlie respiratory epithelium carcinogenesis still remains a largely unresolved issue. Various new therapeutic interventions are in advanced clinical testing or in daily clinical practice based on available preclinical findings. However, the complex molecular interplay that characterizes carcinogenesis requires further investigation to identify the pivotal factors and their interactions that might render the treatment of these malignancies more effective. Insulin-like growth factor-1 (IGF-1) network is a new important signalling cascade in lung carcinogenesis. Here, we integrate updated results that further support the significance of IGF-1 molecular circuitry in respiratory epithelium tumourigenesis, and pose future perspectives regarding its optimal use in the therapeutic field.

The GH1/IGF-1 axis polymorphisms and their impact on breast cancer development

The growth hormone 1/insulin-like growth factor-1 (GH1/IGF-1) axis plays an essential role in the development of the breast by regulating cell proliferation, differentiation and apoptosis. Imbalances within this axis lead to an aberrant signalling and recent research has focussed on the overexpression of these growth factors and their involvement in breast cancer development. The increased understanding of the molecular mechanisms and signalling pathways connected to the GH1/IGF-1 axis has provided important insights into aetiology, prevention and therapy for breast cancer. However, to identify the contribution of the GH1/IGF-1 signalling pathway to cancer risk still remains a challenge since the results of various studies are controversial. Here, we discuss the influence of low-penetrance polymorphisms in the genes along the GH1/IGF-1 axis and their impact on hormone levels and cancer risk, especially breast cancer. We point out what is known about the effects of the variants and show how the interaction of genetic variants affects breast cancer risk.

The prognostic significance of pretreatment plasma levels of insulin-like growth factor (IGF)-1, IGF-2, and IGF binding protein-3 in patients with advanced non-small cell lung cancer

PURPOSE

Insulin-like growth factor (IGF) system is related to cell proliferation and tumor growth. We tested whether pretreatment plasma levels of IGF-1, IGF-2, and IGF binding protein (IGFBP)-3 would predict the prognosis in patients with advanced non-small cell lung cancer (NSCLC).

METHODS

Plasma levels of IGF-1, IGF-2, and IGFBP-3 were measured using enzyme-linked immunoassays from 77 patients with advanced NSCLC enrolled in a phase II study of irinotecan plus cisplatin chemotherapy.

RESULTS

IGF-2 and IGFBP-3 levels were elevated in female patients, non-squamous cell carcinoma, and never smokers. In a univariate Cox proportional hazards model, higher levels of IGF-1, IGF-2, and IGFBP-3 were predictive of longer progression-free (P=0.001, 0.006, and 0.007, respectively) and overall survival (P=0.025, <0.0001, and 0.001, respectively). Multivariate analysis revealed that IGF-1 and IGFBP-3 are independent factors for progression-free survival (P<0.0001 and P=0.001, respectively). In addition, IGF-1, IGF-2, and IGFBP-3 are independently predictive for overall survival (P=0.004, 0.001, and 0.043, respectively).

CONCLUSIONS

High plasma levels of IGF-1, IGF-2, and IGFBP-3 were associated with good prognosis in patients with advanced NSCLC. Further validation of these results is needed to determine the prognostic significance of IGF system in advanced NSCLC.

Variants in the GH-IGF axis confer susceptibility to lung cancer

We conducted a large-scale genome-wide association study in UK Caucasians to identify susceptibility alleles for lung cancer, analyzing 1529 cases and 2707 controls. To increase the likelihood of identifying disease-causing alleles, we genotyped 1476 nonsynonymous single nucleotide polymorphisms (nsSNPs) in 871 candidate cancer genes, biasing SNP selection toward those predicted to be deleterious. Statistically significant associations were identified for 64 nsSNPs, generating a genome-wide significance level of P=0.002. Eleven of the 64 SNPs mapped to genes encoding pivotal components of the growth hormone/insulin-like growth factor (GH-IGF) pathway, including CAMKK1 E375G (OR=1.37, P=5.4x10(-5)), AKAP9 M463I (OR=1.32, P=1.0x10(-4)) and GHR P495T (OR=12.98, P=0.0019). Significant associations were also detected for SNPs within genes in the DNA damage-response pathway, including BRCA2 K3326X (OR=1.72, P=0.0075) and XRCC4 I137T (OR=1.31, P=0.0205). Our study provides evidence that inherited predisposition to lung cancer is in part mediated through low-penetrance alleles and specifically identifies variants in GH-IGF and DNA damage-response pathways with risk of lung cancer.