Insulin-like growth factor (IGF)-I, IGF-binding protein-3 and colorectal adenomas in Japanese men

Exploring Vitamin D Deficiency and IGF Axis Dynamics in Colorectal Adenomas

(1) Colorectal cancer is a major cause of cancer-related death, with colorectal adenomas (CRAs) serving as precursors. Identifying risk factors such as vitamin D deficiency and the insulin-like growth factor (IGF) axis is crucial for prevention. (2) This case-control study included 85 participants (53 CRA patients and 32 controls) who underwent colonoscopy. We measured serum vitamin D3 (cholecalciferol), calcidiol (vitamin D metabolite), calcitriol (active vitamin D metabolite), insulin-like growth factor-1 (IGF-1), and insulin-like growth factor binding protein-3 (IGFBP-3) to explore their associations with CRA risk. (3) Results: We found that lower cholecalciferol levels were a significant risk factor for CRA (OR = 4.63, p = 0.004). Although no significant differences in calcidiol and calcitriol levels were observed between CRA patients and controls, calcidiol deficiency was common in the study population. IGF-1 levels inversely correlated with age, calcitriol, and IGFBP-3 in CRA patients. (4) This study highlights the potential of lower cholecalciferol levels to detect patients at risk of CRA when calcidiol values cannot, suggesting the importance of evaluating different vitamin D metabolites in cancer prevention research. Our findings underscore the need to further investigate the interactions between calcitriol, the active form of vitamin D, and the IGF axis in colorectal cancer development.

Correlation of serum IGF-1, AGEs and their receptors with the risk of colorectal cancer in patients with type 2 diabetes mellitus

Background

According to epidemiological evidence, people with type 2 diabetes mellitus have a higher risk of developing colorectal cancer.

Objective

To examine the relationship between colorectal cancer (CRC) and serum levels of IGF-1, IGF-1R, AGEs,RAGE and sRAGE in patients with type 2 diabetes.

Methods

By using RNA-Seq data of CRC patients from The Cancer Genome Atlas (TCGA) database, we divided the patients into normal group(58 patients)and tumor group(446 patients), and analyzed the expression and prognostic value analysis of IGF-1,IGF1R and RAGE. Cox regression and the Kaplan-Meier method were used to determine the predictive value of target gene on clinical outcomes in CRC patients. In order to further combine CRC with diabetes research,one hundred forty-eight patients hospitalized in the Second Hospital of Harbin Medical University from July 2021 to July 2022 were enrolled and divided into CA and control groups. There were 106 patients in the CA group, including 75 patients with CRC and 31 patients with CRC+T2DM; the control group comprised 42 patients with T2DM. Circulating levels of IGF-1, IGF-1R, AGEs, RAGE, and sRAGE in the serum of the patients were measured using Enzyme-Linked Immunosorbnent Assay (ELISA) kits, and other clinical parameters were also measured during hospitalization. Statistical methods used were χ² test, independent samples t-test and Pearson correlation analysis were. Finally, we controlled for confounding factors and used logistic multi-factor regression analysis.

Results

Bioinformatics analysis showed that IGF-1, IGF1R and RAGE were highly expressed in CRC patients, and the patients with high expression also showed significantly lower overall survival rate. Through Cox regression analysis, IGF-1 can be used as an independent influencing factor of CRC. In the ELISA experiment, serum AGE, RAGE, IGF-1, and IGF-1R levels were higher in the CRC and CRC+T2DM groups than in the T2DM group, but the serum sRAGE concentrations in these groups were lower than those in the T2DM group (P < 0.05). Serum AGE, RAGE, sRAGE, IGF1, and IGF1R levels were higher in the CRC+T2DM group than in the CRC group (P < 0.05). In CRC+T2DM patients, serum AGEs were correlated with age (p = 0.027), and the serum AGE levels in these groups were positively correlated with RAGE and IGF-1 levels (p < 0.001) and negatively correlated with sRAGE and IGF-1R levels (p < 0.001). After correcting for confounding factors based on logistic multiple regression analysis, the effects of age, serum IGF-1 and IGF-1R on the development of CRC in patients with T2DM were statistically significant (p<0.05).

Conclusion

Serum IGF-1 and IGF-1R levels independently influenced the development of CRC in patients with T2DM. Furthermore, IGF-1 and IGF-1R were correlated with AGEs in CRC patients who also had T2DM, suggesting that AGEs may influence the development of CRC in T2DM patients. These findings suggest that we may be able to lower the risk of CRC in the clinic by regulating AGEs through the regulation of blood glucose levels, which will affect IGF-1 and its receptors.

Effect of Insulin and Metformin Combination Treatment on Colon Adenoma and Advanced Adenoma Among DM II

BACKGROUND

The risk for colorectal adenoma and advanced adenoma among diabetes mellitus II (DM II) has been debated to differ with the type of anti-diabetic therapy. Insulin increases whereas metformin decreases the risk for colon adenoma (Ad) and advanced Ad (AAd). There have been no studies to evaluate the effect of combination treatment with insulin and metformin on colon Ad and AAd.

METHODS

The retrospective study included DM II patients undergoing screening colonoscopy. Subjects with incomplete colonoscopy, poor bowel preparation, personal history of colorectal cancer (CRC)/inflammatory bowel disease/hereditary nonpolyposis colorectal cancer/familial adenomatosis polyposis/colectomy or family history of CRC were excluded. Subjects were categorized into group 1 (insulin only), group 2 (metformin only), group 3 (combination of insulin and metformin) and group 4 (miscellaneous). Group 4 was excluded from data analysis. Ad detection rate (ADR) and advanced ADR (AADR) were calculated for each group.

RESULTS

Three hundred thirty-nine subjects composed the study group, with a mean age of 60.0 years and male to female ratio of 1:1.4. Composite ADR and AADR for study population was 35.1 and 15.3 %, respectively. Groups 1, 2 and 3 were composed of 88 (26.0 %), 211 (62.2 %) and 40 (11.8 %) subjects, respectively. ADR for groups 1, 2 and 3 was 40.9, 33.2 and 32.5 %, respectively (p value = 0.413). AADR for groups 1, 2 and 3 was 18.2, 15.2 and 10.0 %, respectively (p value = 0.489).

CONCLUSION

A decremental trend was observed in ADR and AADR across group 1, group 2 and group 3 (p value >0.05).

Circulating levels of IGF-1, IGFBP-3, and IGF-1/IGFBP-3 molar ratio and colorectal adenomas: A meta-analysis

BACKGROUNDS

Insulin-like growth factor-1(IGF-1) promotes cell proliferation and inhibits apoptosis, and is thereby implicated in carcinogenesis. Insulin-like growth factor binding protein-3 (IGFBP-3) may antagonize IGF-1 action, leading to inhibition of the potential tumorigenicity of IGF-1. We conducted this meta-analysis to estimate the association between IGF-1, IGFBP-3 and IGF-1/IGFBP-3 ratio and the risk of colorectal adenomas (CRAs). Further, we investigated whether this association was different between occurrent and recurrent CRA, by adjustment for obesity, and by advanced CRA.

MATERIALS AND METHODS

Pubmed and Embase were searched up to April, 2015 to identify relevant observational studies and summary odds ratio (OR) and the corresponding 95% confidence interval (95% CI) was estimated using a random-effects model.

RESULTS

A total of 12 studies (11 studies including 3038 cases for IGF-1, 12 studies including 3208 cases for IGFBP-3, and 7 studies including 1867 cases for IGF-1/IGFBP-3 ratio) were included in this meta-analysis. The summary ORs of occurrent CRA for the highest versus lowest category of IGF-1, IGFBP-3 and IGF-1/IGFBP-3 ratio were 1.13 (95% CI: 0.95-1.34), 0.99 (0.84-1.16), and 1.05 (0.86-1.29), respectively. Higher IGF-1 and IGF-1/IGFBP-3 ratio were significantly associated with decreased risk of recurrent CRA (OR for IGF-1=0.60 [95% CI: 0.42-0.85]; IGF-1/IGFBP-3 ratio=0.65 [0.44-0.96]). A stratified analysis by advancement of occurrent CRA produced a significant summary OR of IGF-1 for advanced CRA (OR=2.21 [1.08-4.52]) but not for non-advanced CRA (OR=0.89 [0.55-1.45]). We did not find significant publication bias or heterogeneity.

CONCLUSION

Circulating levels of IGF-1, IGFBP-3 and their molar ratio were not associated with the risk of occurrence of CRA, but IGF-1 was associated with the increased risk for occurrence of advanced CRA.

Specific metabolic biomarkers as risk and prognostic factors in colorectal cancer

Advances in genomics, molecular pathology and metabolism have generated many candidate biomarkers of colorectal cancer with potential clinical value. Epidemiological and biological studies suggest a role for adiposity, dyslipidaemia, hyperinsulinemia, altered glucose homeostasis, and elevated expression of insulin-like growth factor (IGF) axis members in the risk and prognosis of cancer. This review discusses some recent past and current approaches being taken by researches in obesity and metabolic disorders. The authors describe three main systems as the most studied metabolic candidates of carcinogenesis: dyslipidemias, adipokines and insulin/IGF axis. However, each of these components is unsuccessful in defining the diseases risk and progression, while their co-occurrence increases cancer incidence and mortality in both men and women.

The association between obesity and colorectal adenoma: systematic review and meta-analysis

OBJECTIVE

Obesity (body mass index [BMI] ≥30) or overweight (25 ≤ BMI ≤29.9) has been reported to be a risk factor for colorectal adenoma (CRA). However, this association remains controversial. The aim of this study was to determine the association between overweight or obesity and CRA.

DESIGN

Systematic review and meta-analysis were conducted using English language studies from EMBASE and MEDLINE. Appropriate observational studies were selected from 1966 through September 2011. Adjusted odds ratios (ORs) were extracted from each study.

RESULTS

One hundred and seventy full-text articles were reviewed after retrieving 1199 initial search results. Five studies in which BMI was treated as continuous variable, three studies in which BMI was dichotomized using a cutoff value of 25, three studies in which BMI was categorized into three groups using values of 22 and 25, and eight studies in which BMI was categorized into three groups using values of 25 and 30 were selected. Regarding risk for CRA, pooled OR [95% CI] of one increment increase in BMI was 1.02 [0.99-1.03] (random effects model [REM]), while that of BMI ≥ 25 was 1.27 [1.15-1.4] (Fixed effects model). Pooled ORs [95% CI] of BMI ≥ 22 and BMI ≥ 25 was 1.42 [0.69-2.9] [REM] and 1.81 [0.36-9.1] [REM], respectively. Pooled ORs [95% CI] of BMI ≥ 25 and BMI ≥ 30 was 1.16 [0.98-1.38] [REM] and 1.47 [1.18-1.83] [REM], respectively.

CONCLUSION

Obesity and overweight are significant risk factors for CRA. However, there are no data showing linear relationship between increasing BMI and CRA.

Insulin, insulin-like growth factor 1 and insulin-like growth factor binding protein 3 serum concentrations in patients with adenomatous colon polyps

INTRODUCTION

Insulin stimulates colonic mucosal cells proliferation directly and by influencing the concentration of insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein 3 (IGFBP-3).

AIM

To estimate serum concentrations of insulin, IGF-1, and IGFBP-3 and to determine the relationships between them and colorectal adenoma location, dysplasia grading, histological type, and size.

MATERIAL AND METHODS

The study included 60 patients with colorectal adenomatous polyps found on colonoscopy and confirmed pathologically. The control group consisted of 30 individuals with no positive findings on colonoscopy. All patients had their blood drawn for assessment of insulin, IGF-1, and IGFBP-3 serum concentrations.

RESULTS

One hundred and nine adenomas (6-40 mm in size) were found in 60 study patients. The average age of patients with multiple polyps was significantly higher than that of patients with single pathologies (61.1 vs. 56.7 years respectively (p < 0.05)). A higher adenoma incidence rate was observed in the distal portion of the colon than the proximal one (50 vs. 10 polyps respectively (p < 0.01)). Higher serum levels of IGF-1 and IGFBP-3 were found in patients with adenomatous polyps than in the control group. The average IGF-1 concentration in patients with adenomas located proximally was also significantly higher compared to those located distally (p < 0.05). The insulin concentration was similar in both groups and not related to clinical data of patients.

CONCLUSIONS

The results indicate the role of IGF-1 and IGFBP-3 in early carcinogenesis of the large intestine, and IGF-1 particularly in malignant transformation in the proximal part of the organ.

Insulin therapy and colorectal adenomas in patients with diabetes mellitus

BACKGROUND

Patients with type 2 diabetes mellitus (DM) are at increased risk for colorectal adenomas and cancer because of endogenous hyperinsulinemia. Exogenous insulin therapy has been associated with higher colorectal cancer incidence. The aim of this study was to evaluate the association between exogenous insulin therapy and adenoma formation, accounting for duration of therapy and location and stage of the adenoma.

METHODS

We conducted a cross-sectional study of patients with type 2 diabetes between the ages of 50 and 80 years who completed full colonoscopies. Cases were patients with any adenoma on index colonoscopy. Patients without any adenoma composed the control group. Multivariable logistic regression was used to calculate odds ratios (OR) and associated confidence intervals (CI).

RESULTS

Compared with the controls, case patients (n = 196) did not have a significantly increased odds of insulin exposure, when exposure was defined as 12 months or more of insulin use compared with no insulin. However, the odds of insulin exposure among the cases was significantly increased when exposure was defined as 18 months or more (OR 1.6, 95% CI 1.1-2.5), 24 months or more (OR 1.7, CI 1.1-2.6), and 36 months or more (OR 2.0, 95% CI 1.2-3.4) of insulin use (test for trend P = 0.05). A similar trend in insulin exposure was seen among type 2 diabetics with advanced adenomas. Adenoma location was not significantly affected by insulin therapy.

CONCLUSIONS

Chronic insulin therapy is associated with increased risk of colorectal adenomas in patients with type 2 diabetes.

IMPACT

Diabetes patients receiving insulin may need more stringent colon cancer screening.

Serum IGF1, IGF2 and IGFBP3 and risk of advanced colorectal adenoma

The insulin-like growth factor (IGF) signaling pathway is involved in cell proliferation and differentiation. Elevated serum IGF1 levels have been associated with increased colorectal cancer risk; however, studies of this association with colorectal adenoma are inconclusive. We examined serum IGF1, IGF2 and IGFBP3 levels in relation to risk of advanced colorectal adenoma in a case-control study within the prostate, lung, colorectal and ovarian cancer screening trial. A total of 764 advanced, left-sided colorectal adenoma cases and 775 controls frequency-matched on gender and ethnicity, without evidence of a left-sided polyp on sigmoidoscopy were included in the current study. Serum levels of IGF1, IGF2 and IGFBP3 were measured using an enzyme linked immunosorbent assay in serum samples collected at baseline. Logistic regression was used to estimate the odds ratios (OR) and 95% confidence intervals (CI) for the associations adjusting for age, race, sex, year of blood draw, body mass index, smoking and education. Higher IGF1 levels were associated with increased adenoma risk: ORs = 1.58 (95% CI = 1.16-2.16), 1.42 (95% CI = 1.04-1.93), and 1.80 (95% CI = 1.30-2.47) for the second, third and fourth quartiles, respectively (p(trend) = 0.002). Elevated IGF2 levels were also associated with increased adenoma risk (OR = 1.43, 95% CI = 1.05-1.96 for the fourth vs. first quartile, p(trend) = 0.02), but the association was no longer significant after adjustment for IGF1 (p(trend) = 0.28). IGFBP3 levels were not associated with adenoma risk. Our analysis showed a significant positive association between circulating IGF1 levels and risk of advanced colorectal adenoma, suggesting that IGF1 is associated with the pivotal precursor to colorectal cancer.

Relationships between insulin-like growth factor i and selected clinico-morphological parameters in colorectal cancer patients

Insulin Like Growth Factor (IGF I) as the one of the strongest growth factors which can affect cancers development including colorectal cancer. IGF I induces processes of the cells growth and division. It regulates cells cycle and inhibits apoptosis. There is limited data about correlation between IGF I and staging of the tumor. The aim of the study was estimation of the clinical usefulness of IGF I concentration in the serum of the patients with colorectal cancer.

MATERIAL AND METHODS

We have examined 125 individuals with colorectal cancer. The age range was 36 to 92 years. They have been operated in the 2nd Departament of The Gastrointestinal Surgery of the Medical University in Białystok. Serum concentration of the IGF I have been estimated using immunoassay ELISA before and after operation. Correlation between serum level of IGF I and clinicopathologic features: age, gender, localisation of the primary tumor, TNM stage of tumor, histological type and histological grade (G) of the cancer have been estimated.

RESULTS

Our study revealed statistically significant increased serum concentration of IGF I in patients with locally advanced colorectal cancer (pT3 and pT4) comparing to less advanced (pT2) The investigations showed higher serum concentration of IGF I in patients with poorly differentiated cancers (G3) than in moderately differentiated. Similarly higher serum concentration of IGF I were found in male, in patients older than 60 years and in mucigenous colorectal cancers.

CONCLUSIONS

Our results indicated that IGF I can be one of the factors of the prognosis in colorectal cancer development.

POTENTIAL MECHANISMS OF CANCER PREVENTION BY WEIGHT CONTROL

Weight control via dietary caloric restriction and/or physical activity has been demonstrated in animal models for cancer prevention. However, the underlying mechanisms are not fully understood. Body weight loss due to negative energy balance significantly reduces some metabolic growth factors and endocrinal hormones such as IGF-1, leptin, and adiponectin, but enhances glucocorticoids, that may be associated with anti-cancer mechanisms. In this review, we summarized the recent studies related to weight control and growth factors. The potential molecular targets focused on those growth factors- and hormones-dependent cellular signaling pathways are further discussed. It appears that multiple factors and multiple signaling cascades, especially for Ras-MAPK-proliferation and PI3K-Akt-anti-apoptosis, could be involved in response to weight change by dietary calorie restriction and/or exercise training. Considering prevalence of obesity or overweight that becomes apparent over the world, understanding the underlying mechanisms among weight control, endocrine change and cancer risk is critically important. Future studies using "-omics" technologies will be warrant for a broader and deeper mechanistic information regarding cancer prevention by weight control.

IGF-IR in patients with advanced colorectal cancer in correlation with certain clinico-morphological factors: Initial report

The insulin-like growth factor (IGF) system comprises two types of peptides (IGF-I and IGF-II), two types of receptors (IGF-IR and IGF-IIR) and six IGF-binding proteins (BP). This system is mainly responsible for the growth and division of cells in the body, regulation of the cell cycle and prevention of apoptosis. The expression of IGF-IR was assessed in the cells of resected primary colorectal tumours in 88 patients (age, 36-87 years; mean 64.78; males, 48 and females, 40) treated surgically at the Second Department of General and Gastroenterological Surgery, Medical University of Bialystok, Poland, in relation to various clinico-morphological factors. The post-operative material was analysed to find the histological type, location of lesions, lymph node involvement staging, distant metastases (pTNM classification), staging in Dukes' classification and the histopathological differentiation grade. The expression of IGF-IR in colorectal cancer cells was assessed using an immunohistochemical method. The findings were subjected to statistical analysis (Chi-square test, multivariation test and Mann-Whitney U test). A positive IGF-IR expression (in at least 10% of cancer cells) was observed in 44 patients. The mean immunoreactive cell count for IGF-IR in all of the tumours studied was 30.79%. The current study showed no correlation of IGF-IR expression in colorectal cancer cells with characteristics such as age and gender of patients, tumour location, type, histological differentiation or histopathological advancement. Immunohistological determination of IGF-IR expression in advanced colorectal cancer cells revealed controversial scores. Evaluation should be confirmed by using other methods and enhanced to include adenomas and early colorectal cancers.

Increase in circulating levels of IGF-1 and IGF-1/IGFBP-3 molar ratio over a decade is associated with colorectal adenomatous polyps

High levels of circulating insulin-like growth factor-1 (IGF-1) have been associated with increased risk of several cancers. Regarding colorectal cancer, these associations are generally weak. We hypothesized that an increase in IGF-1 over time would be a stronger risk factor for cancer-related outcomes than the actual levels. In this analysis we utilized existing data from the Insulin Resistance and Atherosclerosis Study (IRAS). Circulating IGF-1 levels and molar ratios of IGF-1 to IGF binding protein 3 (IGFBP-3) were measured at three time points, within a 10-year follow-up period. We examined the associations of increase of the two variables with the presence of colorectal adenoma at the end of follow-up among participants with normal glucose tolerance at baseline. This included 143 individuals, from which 24 were diagnosed with adenomatous polyps. Although the mean levels of IGF-1 and IGF-1/IGFBP-3 decline with age, ~ 30% of the participants showed an increase of at least fifteen percent ("ever increase") in one or both of these variables, compared to baseline. We found a positive association between "ever increase" in IGF-1 or IGF-1/IGFBP-3 and the presence of colorectal adenoma: ORs were 3.81 (95% CI: 1.30-10.8) and 2.83 (95% CI: 1.00-8.22), respectively. No association was found when analyzing the actual levels of both variables at any time point. Our data suggest that an increase in circulating IGF-1 or IGF-1/IGFBP-3 may represent a disturbed GH/IGF1 homeostasis, which could favor the development of precancerous lesions such as colorectal adenoma.

Gender difference in the association of insulin and the insulin-like growth factor axis with colorectal neoplasia

OBJECTIVE

Accumulating evidence has implicated insulin and the insulin-like growth factor (IGF) axis in colorectal carcinogenesis. Of interest, adiposity is likely to impose a greater risk on men than on women, which indicates that the association of insulin and the IGF axis with colorectal neoplasia may differ by gender. However, epidemiological evidence for this possible gender difference is limited to date.

METHODS

We measured plasma concentrations of C-peptide, IGF-I and IGF-binding proteins (IGFBPs) 1 and 3 in 1520 healthy volunteer examinees who underwent total colonoscopy between February 2004 and February 2005, and cross-sectionally investigated the association of these biomarkers with colorectal adenoma by gender. An unconditional logistic regression model was used to estimate odds ratios (ORs) and their 95% confidence intervals (CIs) for colorectal adenoma after adjustment for potential confounders.

RESULTS

We observed a positive association of C-peptide and IGF-I (P (trend)<0.001 and 0.02, respectively) and an inverse association of IGFBP-1 (P (trend)=0.002) with colorectal adenoma in men. Adjusted ORs of colorectal adenoma for the highest compared with the lowest quartile were also statistically significant for C-peptide (OR: 2.62, 95% CI: 1.71-4.01), IGF-I (OR: 1.63, 95% CI: 1.08-2.46) and IGFBP-1 (OR: 0.49, 95% CI: 0.32-0.75). In contrast, no measurable association was seen in women. Corresponding ORs for C-peptide, IGF-I and IGFBP-1 were 0.98 (95% CI: 0.56-1.71), 0.79 (95% CI: 0.44-1.43) and 1.05 (95% CI: 0.60-1.86), respectively. The gender difference was statistically significant for C-peptide (P (interaction)=0.03) and marginally significant for IGF-I and IGFBP-1 (P (interaction)=0.14 and 0.12, respectively).

CONCLUSION

Our observations suggest that insulin and the IGF axis act differently by gender in colorectal carcinogenesis, at least in its early stage. The findings of this study further our understanding of the complexities of the gender difference in the association between adiposity and colorectal neoplasia.

Serum levels of IGF-I, IGFBP-3 and colorectal cancer risk: results from the EPIC cohort, plus a meta-analysis of prospective studies

Several prospective studies have shown a moderate positive association between increasing circulating insulin-like growth factor-I (IGF-I) levels and colorectal cancer risk. However, the associations were often statistically nonsignificant, and the relationship of cancer risk with IGF-I's major binding protein, IGFBP-3, showed major discrepancies between studies. We investigated the association of colorectal cancer risk with serum IGF-I, total and intact IGFBP-3, in a case-control study nested within the EPIC cohort (1,121 cases of colorectal cancer and 1,121 matched controls). Conditional logistic regression was used to adjust for possible confounders. Our present study results were combined in a meta-analysis with those from 9 previous prospective studies to examine the overall evidence for a relationship of prediagnostic serum IGF-I with colorectal cancer risk. In the EPIC study, serum concentrations of IGF-I and IGFBP-3 showed no associations with risk of colorectal cancer overall. Only in subgroup analyses did our study show moderate positive associations of IGF-I levels with risk, either among younger participants only (and only for colon cancer) or among participants whose milk intakes were in the lowest tertile of the population distribution (RR for an increase of 100 ng/ml = 1.43 [95% CI = 1.13-1.93]). Nevertheless, in the meta-analysis a modest positive association remained between serum IGF-I and colorectal cancer risk overall (RR = 1.07 [1.01-1.14] for 1 standard deviation increase in IGF-I). Overall, data from our present study and previous prospective studies combined indicate a relatively modest association of colorectal cancer risk with serum IGF-I.

Predictors of variation in serum IGF1 and IGFBP3 levels in healthy African American and white men

BACKGROUND

Individual variation in circulating insulinlike growth factor-1 (IGF1) and its major binding protein, insulinlike growth factor binding protein-3 (IGFBP3), have been etiologically linked to several chronic diseases, including some cancers. Factors associated with variation in circulating levels of these peptide hormones remain unclear.

METHODS

Multiple linear regression models were used to determine the extent to which sociodemographic characteristics, lifestyle factors, personal and family history of chronic disease, and common genetic variants, the (CA)n repeat polymorphism in the IGF1 promoter and the IGFBP3-202 A/C polymorphism (rs2854744) predict variation in IGF1 or IGFBP3 serum levels in 33 otherwise healthy African American and 37 white males recruited from Durham Veterans Administration Medical Center.

RESULTS

Predictors of serum IGF1, IGFBP3, and the IGF1:IGFBP3 molar ratio varied by race. In African Americans, 17% and 28% of the variation in serum IGF1 and the IGF1:IGFBP3 molar ratio, were explained by cigarette smoking and carrying the IGF1 (CA)19 repeat allele, respectively. Not carrying at least 1 IGF1 (CA)19 repeat allele and a high body mass index explained 8% and 14%, respectively, of the variation IGFBP3 levels. These factors did not predict variation of these peptides in whites.

CONCLUSION

If successfully replicated in larger studies, these findings would add to recent evidence, suggesting known genetic and lifestyle chronic disease risk factors influence IGF1 and IGFBP3 circulating levels differently in African Americans and whites.

Acromegaly, growth hormone and cancer risk

Acromegaly is an endocrine disorder characterized by sustained hypersecretion of growth hormone (GH) with concomitant elevation of insulin-like growth factor I (IGF-I) associated with premature mortality from cardiopulmonary diseases and certain malignancies. In particular, there is a two-fold increased risk of developing colorectal cancer. Possible mechanisms underlying this association include elevated levels of circulating GH and IGF-I, but several other plausible processes may be relevant. In a parallel literature, there has been debate whether GH replacement therapy is associated with increased cancer risk in three scenarios: (1) tumour recurrence in children with previously treated cancer; (2) second neoplasms (SNs) in survivors of childhood cancer treated with GH; and (3) de-novo cancer in non-cancer patients treated with GH. The general evidence suggests no increased risk in scenario 1. Through a maze of complex study designs, there is inconclusive evidence of a very modest increase in cancer risk in treated GH-deficiency patients in scenarios 2 and 3, but it is likely that the cumulative risk equates to that of the general population. This emphasizes the need for patient selection balanced against the known morbidity of untreated GH deficiency.

Local IGFBP-3 mRNA expression, apoptosis and risk of colorectal adenomas

Background

IGF binding protein-3 (IGFBP-3) regulates the bioavailability of insulin-like growth factors I and II, and has both anti-proliferative and pro-apoptotic properties. Elevated plasma IGFBP-3 has been associated with reduced risk of colorectal cancer (CRC), but the role of tissue IGFBP-3 is not well defined. We evaluated the association between tissue or plasma IGFBP-3 and risk of colorectal adenomas or low apoptosis.

Methods

Subjects were consenting patients who underwent a clinically indicated colonoscopy at UNC Hospitals and provided information on diet and lifestyle. IGFBP-3 mRNA in normal colon was assessed by real time RT-PCR. Plasma IGFBP-3 was measured by ELISA and apoptosis was determined by morphology on H & E slides. Logistic regression was used to compute odds ratio (OR) and 95% confidence intervals.

Results

We observed a modest correlation between plasma IGFBP-3 and tissue IGFBP-3 expression (p = 0.007). There was no significant association between plasma IGFBP-3 and adenomas or apoptosis. Tissue IGFBP-3 mRNA expression was significantly lower in cases than controls. Subjects in the lowest three quartiles of tissue IGFBP-3 gene expression were more likely to have adenomas. Consistent with previous reports, low apoptosis was significantly associated with increased risk of adenomas (p = 0.003). Surprisingly, local IGFBP-3 mRNA expression was inversely associated with apoptosis.

Conclusion

Low expression of IGFBP-3 mRNA in normal colonic mucosa predicts increased risk of adenomas. Our findings suggest that local IGFBP-3 in the colon may directly increase adenoma risk but IGFBP-3 may act through a pathway other than apoptosis to influence adenoma risk.

Metabolic syndrome, hyperinsulinemia, and colon cancer: a review

An impressive body of epidemiologic data collected over the past decade indicates that the risk of colon cancer is elevated in those with metabolic syndrome. This evidence includes studies that examined the risk of colon cancer or adenoma in relation to determinants of the metabolic syndrome (obesity, abdominal distribution of adiposity, and physical inactivity), clinical consequences of this syndrome (type 2 diabetes and hypertension), plasma or serum components of the definition of metabolic syndrome (hypertriglyceridemia, hyperglycemia, and low HDL cholesterol), and markers of hyperinsulinemia or insulin resistance (insulin and C-peptide), which is the underlying metabolic defect of the metabolic syndrome. The mechanism underlying these associations is unknown but may involve the influence of hyperinsulinemia in enhancing free or bioavailable concentrations of insulin-like growth factor-1. Future studies should also be based on better measurements of insulin resistance, beta-cell depletion, and insulin responses to better assess which aspects of insulin resistance are most closely related to the risk of colon neoplasia.

The role of obesity and related metabolic disturbances in cancers of the colon, prostate, and pancreas

Recent evidence indicates that obesity and related metabolic abnormalities are associated with increased incidence or mortality for a number of cancers, including those of the colon, prostate, and pancreas. Obesity, physical inactivity, visceral adiposity, hyperglycemia, and hyperinsulinemia are relatively consistent risk factors for colon cancer and adenoma. Also, patients with type 2 diabetes mellitus have a higher risk of colon cancer. For prostate cancer, the relationship to obesity appears more complex. Obesity seems to contribute to a greater risk of aggressive or fatal prostate cancer but perhaps to a lower risk of nonaggressive prostate cancer. Furthermore, men with type 2 diabetes mellitus are at lower risk of developing prostate cancer. Long-standing type 2 diabetes increases the risk of pancreatic cancer by approximately 50%. Furthermore, over the past 6 years, a large number of cohort studies have reported positive associations between obesity and pancreatic cancer. Together with data from prediagnostic blood specimens showing positive associations between glucose levels and pancreatic cancer up to 25 years later, sufficient evidence now supports a strong role for diabetes and obesity in pancreatic cancer etiology. The mechanisms for these associations, however, remain speculative and deserve further study. Hyperinsulinemia may be important, but the role of oxidative stress initiated by hyperglycemia also deserves further attention.

Insulin resistance, apoptosis, and colorectal adenoma risk

Compelling evidence from epidemiologic studies indicates that elevated circulating insulin-like growth factor (IGF)-I, insulin resistance, and associated complications, such as elevated fasting plasma insulin, glucose and free fatty acids, glucose intolerance, increased body mass index, and visceral adiposity, are linked with increased risk of colorectal cancer. However, the role of insulin and markers of glucose control in the development of adenomas, precursors to colorectal cancer, has not been fully explored. We evaluated the relationship between plasma insulin, glucose, IGF-I, IGF-II, IGF-binding protein-3 (IGFBP-3), apoptosis, and colorectal adenomas in a case-control study. Participants were drawn from consenting patients undergoing colonoscopy at the University of North Carolina hospitals (Chapel Hill, NC). Participants were classified as cases or controls based on whether they had one or more colorectal adenomatous polyps. Fasting plasma insulin, IGF-I, IGF-II, and IGFBP-3 levels were assessed by ELISA. Glucose was measured by glucose hexokinase assay. Apoptosis was assessed by morphology on H&E-stained sections. Dietary and lifestyle information were obtained by telephone interview. Logistic regression was used to examine the association between adenoma status and insulin-IGF markers. Adenoma cases (n = 239) and adenoma-free controls (n = 517) provided rectal biopsies and/or blood samples and interview data. Consistent with prior findings, cases were more likely to be males, older, have higher waist-to-hip ratio, lower calcium intake, lower apoptosis, and less likely to report nonsteroidal anti-inflammatory drug use. Those in the highest quartile of insulin (adjusted odds ratio, 2.2; 95% confidence interval, 1.1-4.2) and glucose (adjusted odds ratio, 1.8; 95% confidence interval, 0.9-3.6) were more likely to have an adenoma compared with the lowest quartile. Similarly, subjects in the highest two quartiles of insulin were more likely to be in the lowest two quartiles of apoptosis. Overall, there were no significant differences between mean circulating levels of glucose, IGF-I, IGF-II, and IGFBP-3 among cases and controls and no association between these variables and apoptosis. The results provide novel evidence that elevated insulin and glucose are associated with increased adenoma risk and decreased apoptosis in normal rectal mucosa. These findings suggest that insulin may act early in the adenoma-carcinoma sequence to promote the development of colorectal adenoma by decreasing apoptosis in the normal mucosa.

Insulin-like growth factor-I and insulin are associated with the presence and advancement of adenomatous polyps

BACKGROUND & AIMS

Insulin and insulin-like growth factor-I (IGF-I) affect proliferation, differentiation, and apoptosis and are potential risk factors for colorectal cancer (CRC). Visceral obesity, possibly via hyperinsulinemia, has also been linked to CRC risk. We evaluated the relationship of insulin, IGF-I, insulin-like growth factor binding protein (IGFBP) 3, and visceral adipose tissue (VAT) in subjects with adenomatous polyps, the precursor lesion of colorectal cancer.

METHODS

Participants were asymptomatic subjects who underwent screening flexible sigmoidoscopy (FSG) within the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. Subjects underwent single-slice, computerized tomography scanning to measure VAT and serum fasting insulin, IGF-I, and IGFBP-3 measurements.

RESULTS

Four hundred fifty-eight subjects were enrolled, of which 202 subjects had an adenoma, 70 of which were an advanced adenoma. IGF-I (P = .02), IGF-I/IGFBP-3 ratio (P = .003), and insulin (P = .02) were significantly increased in subjects with adenomas compared with controls. In an unadjusted logistic regression analysis using sex-specific quartile cut points, subjects in quartile 4 in comparison with quartile 1 of IGF-I (odds ratio [OR] = 1.7; [95% CI: 1.0-2.9], Ptrend = .03), IGF-I/IGFBP-3 ratio (OR = 1.9 [95% CI: 1.1-3.3], Ptrend = .01), and insulin (OR = 2.1 [95% CI: 1.2-3.6], Ptrend = .04) were at increased risk of adenoma. When limiting the case group to advanced adenomas, the effect was more pronounced: IGF-I (OR = 2.8 [95% CI: 1.3-6.2], Ptrend = .006), IGF-I/IGFBP-3 ratio (OR = 2.3, [95% CI: 1.0-5.2], Ptrend = .04), and insulin (OR = 2.3 [95% CI: 1.1-4.9], Ptrend = .14). Visceral adipose tissue was not associated with adenoma risk.

CONCLUSIONS

Levels of IGF-I, ratio of IGF-I/IGFBP-3, and insulin are associated with adenomas and even more so with advanced adenomas. These data support the hypothesis that insulin and IGF-I may contribute to the development and advancement of adenomatous polyps.

The role of the insulin-like growth factor system in colorectal cancer: review of current knowledge

BACKGROUND

The insulin-like growth factor system, which includes insulin-like growth factors (IGF-I and IGF-II), IGF receptors (IGF-IR and IGF-IIR) and IGF binding proteins (IGFBPs), plays an important role in epithelial growth, anti-apoptosis and mitogenesis. There is a growing body of evidence showing that IGFs control growth and proliferation of several types of cancer. This review introduces the latest information on the biology of the IGF system and its pathophysiological role in the development of colorectal cancer.

DISCUSSION

The growth promoting effects of IGF-I and IGF-II on cancer cells are mediated through the IGF-IR, which is a tyrosine kinase and cancer cells with a strong tendency to metastasise have a higher expression of the IGF-IR. Most of the IGFs in circulation are bound to the IGFBPs, which regulate the bioavailability of the IGFs. All IGFBPs inhibit IGF action by high affinity binding, while some of them also potentiate the effects of IGFs. Colon cancer cells produce specific proteases that degrade the IGFBP so that the IGF will be free to act on the cancer cell in an autocrine manner. Therefore, the IGFBPs play a crucial role in the development of the cancer.

CONCLUSION

The current knowledge about the link between IGFs and colon cancer is mainly based on in vitro investigations. Further in vivo study is needed to understand the exact role of the IGF system, especially its binding proteins, so that they can be manipulated for the prevention and treatment of colorectal cancer.

The Insulin-like Growth Factor System in Cancer Prevention: Potential of Dietary Intervention Strategies

The insulin-like growth factor (IGF) system is related to proliferation and tumor growth, and high levels of circulating IGF-I are thought to be a risk factor for several types of cancer. This review summarizes the epidemiologic evidence for an association between circulating IGF-I and cancer risk as well as the experimental evidence for a causal relation between the endocrine IGF system and tumor growth. The potential for dietary intervention to alter the IGF system and thereby cancer risk is supported by several lines of evidence. Postulated mechanisms of action are as follows: (a) reduction of levels of circulating IGF-I, which will decrease activation of the IGF-I receptor and subsequent signaling pathways; (b) increasing local IGF binding proteins, which may have IGF-dependent effects through obstruction of IGF interaction with local IGF-I receptor as well as IGF-independent effects; and (c) interference with estrogens and estrogen receptor action, which may have direct (and possibly synergistic) effects on IGF signaling. An overview is given of the epidemiologic studies on dietary determinants of circulating IGF-I. Examples of dietary factors, such as dairy protein, lycopene, and phytoestrogens, are used to illustrate the potential mode of action of dietary interventions that may act on the IGF system. In conclusion, the IGF system has every potential to serve as an intermediate for cancer (chemo)prevention studies. On the short term, more research initiatives aimed at the effects of specific food components or dietary strategies on the IGF system both in animal models and in humans are warranted.