Insulin-like growth factor-I, soy protein intake, and breast cancer risk

Previous studies have found that estrogen enhances the effect of insulin-like growth factor-I (IGF-I) levels on breast cancer cell growth. Participants in the Shanghai Breast Cancer Study (SBCS) consumed large amounts of soy that was high in isoflavones, which act as weak estrogens and as anti-estrogens. We assessed whether soy protein intake modified the effect of IGF-I levels on breast cancer risk. The SBCS is a population-based case-control study of breast cancer among women aged 25-64 conducted between 1996 and 1998 in urban Shanghai. In-person interviews were completed with 1,459 incident breast cancer cases ascertained through a population-based cancer registry and 1,556 controls randomly selected from the general population (with respective response rates of 91% and 90%). This analysis is restricted to the 397 cases and 397 matched controls for whom information on IGF-I levels was available. For premenopausal breast cancer, we found nearly significant interactions between soy protein intake and IGF-I levels (P = 0.080) and insulin-like growth factor-binding protein-3 (IGFBP-3) levels (P = 0.057). The direction of the interaction appeared to be negative for IGF-I levels but was positive for IGFBP-3 levels. No interaction was evident between soy protein intake and IGF-I or IGFBP-3 levels among postmenopausal women. Our results suggest that soy protein intake may negatively modulate the effect of IGF-I and may positively modulate the effect of IGFBP-3 levels on premenopausal breast cancer risk. Further studies are needed to confirm our finding and to understand the biological mechanisms of these potential interactions.     

Effects of alcohol on insulin-like growth factor I and insulin-like growth factor binding protein 3 in postmenopausal women

BACKGROUND: Increased circulating insulin-like growth factor I (IGF-I) concentrations, frequently adjusted for IGF binding protein 3 (IGFBP-3), have been associated with increased risk of several types of cancer, including colon, prostate, and breast. Studies have suggested that alcohol may affect IGF-I or IGFBP-3; however, controlled feeding studies to assess alcohol's effects on IGF-I or IGFBP-3 have not been conducted. OBJECTIVE: To determine whether chronic, moderate alcohol intake affects serum IGF-I or IGFBP-3 concentrations, we performed a controlled, crossover feeding study. DESIGN: Fifty-three postmenopausal women were randomly assigned to consume 0 g (control), 15 g (one drink), or 30 g (2 drinks) alcohol daily for 8 wk and were rotated through the other 2 intake levels in random order. All foods and beverages were provided during the intervention. Individuals were monitored and calories adjusted to maintain constant weight, and serum was collected at the end of each diet period. RESULTS: Compared with the effects of 0 g alcohol/d, IGF-I concentrations were nearly unchanged by 15 g alcohol/d (0.8%; 95% CI: -3.2%, 3.5%) but decreased significantly by 4.9% (95% CI: -8.0%, -1.6%) with 30 g alcohol/d. IGFBP-3 concentrations significantly increased by 3.0% (95% CI: 0.4%, 5.6%) with 15 g alcohol/d but did not increase significantly with 30 g/d (1.8%; 95% CI: -0.9%, 4.5%). CONCLUSIONS: To our knowledge, this is the first published controlled diet study to find that in postmenopausal women, when weight is kept constant, alcohol consumption reduces the amount of serum IGF-I potentially available for receptor binding. These findings suggest that the effect of alcohol intake should be considered in studies of IGF-I, IGFBP-3, and cancer in postmenopausal women.     

Relationship between a wide range of alcohol consumptions, components of the insulin-like growth factor system and adiponectin

OBJECTIVE: To explore the relation between a wide range of alcohol consumptions and levels of the components of insulin-like growth factor system (IGFs) and adiponectin in humans. DESIGN: A cross-sectional study using controls from a case-control study on ovarian and endometrial cancer. SETTINGS: The study included women hospitalized between 1999 and 2002 in Pordenone, Italy. SUBJECTS: One hundred and eight cancer-free (controls) with a median age of 61 years (range 29-79 years), admitted for acute conditions unrelated to gynecologic, hormonal or metabolic disorders or diseases leading to dietary modifications. INTERVENTIONS: Levels of IGF-I (total and free), total IGF-II, IGF-binding protein 1 (IGFBP-1), IGFBP-3 and adiponectin were individually measured, and their distributions across strata of alcohol consumption were tested by the Kruskal-Wallis statistic. RESULTS: Median concentrations of total IGF-I were higher (P<0.01) in women reporting low (151 ng/ml) or no alcohol consumption (134 ng/ml) compared to drinkers of 12-23 g/day (103 ng/ml) or >or=24 g/day (118 ng/ml). Median concentrations were higher (P=0.05) for IGFBP-3 in non-drinkers (2333 ng/ml) and in light drinkers (2647 ng/ml) compared to drinkers of >or=24 g/day (2090 ng/ml). No statistically significant difference emerged for other IGFs across levels of alcohol intakes. Adiponectin was slightly lower for non-drinkers, compared to all drinkers categories. CONCLUSIONS: Our study suggests that alcohol consumption is related to circulating levels of components of the IGF system and adiponectin. These results may have a potential impact on the prevention of several chronic diseases. SPONSORSHIP: Italian Association for Research on Cancer, Milan, Italy, and Italian League against Tumours, Milan, Italy.     

卵巢癌患者围手术期血清胰岛素样生长因子-2和胰岛素样生长因子结合蛋白-3检测的临床意义

目的探讨卵巢癌患者围手术期血清胰岛素样生长因子-2（IGF-2）和胰岛素样生长因子结合蛋白-3（IGFBP-3）的变化及其临床意义。方法采用酶联吸附免疫法（ELISA）测定40例健康对照组及82例卵巢癌患者手术前后血清IGF-2和IGFBP-3的水平,观察健康对照组与卵巢癌患者手术前后血清IGF-2和IGFBP-3的水平变化,分析卵巢癌病人血清IGF-2和IGFBP-3水平与临床特征的关系。结果卵巢癌手术前病人血清IGF．2及IGFBP-3水平明高于正常对照组[（101．5±22．2）ne／ml,（49．3±15．6）ng／mlvs（69．6±17．7）ng／ml,（23．9±11．3）rig／ml,t=3．74,2．85,P〈0．05];卵巢癌病人有淋巴结转移者血清IGF-2水平[（109．4±20．0）rig／m1]高于无淋巴结转移者[（89．9±16．6）ng／frll]（t’=4．10,P〈0．05）,而IGFBP-3水平[（39．8±11．1）ng／m1]低于无淋巴结转移者[（55．8±19．2）ng／m1]（t’=4．49,P〈0．05）;肿瘤临床TNM分期中III—IV期者血清IGF-2水平[（107．5±24．0）ng／m1]高于I—II期者[（91．6±17．7）ng／m1]（t=2．83,P〈0．05）,而IGFBP-3水平[（41．7±16．9）ng／m1]低于I～II期者[（56．9±19．1）ng／m1]（t=2．37,P〈0．05）,根治性手术组病人术后IGF-2及ICFBP-3水平明显低于术前[（103．4±27．2）ng／ml,（50．2±16．6）ng／mlvs（86．6±12．3）ng／IIll,（41．1±17．1）ng／ml,f=2．48,3．32,P〈0．05],姑息性手术组病人术前术后血清IGF-2及IGFBP．3水平无明显变化（P〉0．05）。根治性手术组病人术后血清IGF-2及IGFBP-3水平低于姑息性手术组术后[（86．6±12．3）ng／ml,（41．1±17．1）ng／mlvs（103．2±26．0）rig／ml,（45．3±14．9）ng／ml,t’=3．46,t=2．67,P〈0．05]。结论卵巢癌患者血清IGF-2和IGFBP-3的水平与肿瘤的浸润转移、临床分期及根治性手术有关,动态检测卵巢癌患者血清IGF-2和IGFBP-3的变化,有助于估计患者的预后。     

Relation of insulin-like growth factor (IGF) I and IGF-binding protein 3 concentrations with intakes of fruit, vegetables, and antioxidants

BACKGROUND: Fruit, vegetable, and antioxidant intakes may reduce the risk of several insulin-like growth factor (IGF)-related chronic diseases, such as certain types of cancers and cardiovascular diseases. OBJECTIVE: This study investigated whether intakes of fruit, vegetables, and antioxidants (beta-carotene, lycopene, and vitamin C) are associated with plasma IGF-I and IGF-binding protein 3 (IGFBP-3) concentrations. DESIGN: Plasma IGF-I and IGFBP-3 concentrations were measured in 1542 healthy women by enzyme-linked immunosorbent assay. A self-administered semiquantitative food-frequency questionnaire was used to estimate mean daily dietary intakes of fruit, vegetables, and antioxidants over the year preceding blood sampling. Multivariate analyses were performed by using generalized linear models to evaluate the association of quintiles of daily intakes with concentrations of growth factors. RESULTS: A higher intake of citrus fruit was associated with higher concentrations of IGF-I (215 ng/mL for quintile 5 compared with 205 ng/mL for quintile 1; P for trend = 0.04) and with lower concentrations of IGFBP-3 (4803 ng/mL for quintile 5 compared with 4960 ng/mL for quintile 1; P for trend = 0.04). Higher dietary vitamin C intake was associated with higher concentrations of IGF-I (214 ng/mL for quintile 5 compared with 204 ng/mL for quintile 1; P for trend = 0.02) and lower concentrations of IGFBP-3 (4813 ng/mL for quintile 5 compared with 4953 ng/mL for quintile 1; P for trend = 0.03). Total intake of fruit and vegetables and intakes of other botanical fruit and vegetable subgroups, beta-carotene, and lycopene were not related to either IGF-I or IGFBP-3 concentrations. CONCLUSION: Women with higher intakes of citrus fruit or dietary vitamin C tend to have higher plasma concentrations of IGF-I and lower plasma concentrations of IGFBP-3.     

Lycopene supplementation elevates circulating insulin-like growth factor binding protein-1 and -2 concentrations in persons at greater risk of colorectal cancer

BACKGROUND: Higher circulating insulin-like growth factor I (IGF-I) concentrations have been related to a greater risk of cancer. Lycopene intake is inversely associated with cancer risk, and experimental studies have shown that it may affect the IGF system, possibly through an effect on IGF-binding proteins (IGFBPs). OBJECTIVE: The objective of our study was to investigate the effect of an 8-wk supplementation with tomato-derived lycopene (30 mg/d) on serum concentrations of total IGF-I, IGF-II, IGFBP-1, IGFBP-2, and IGFBP-3. DESIGN: We conducted a randomized, placebo-controlled, double-blinded crossover study in 40 men and 31 postmenopausal women with a family history of colorectal cancer, a personal history of colorectal adenoma, or both. RESULTS: Lycopene supplementation significantly (P = 0.01) increased serum IGFBP-1 concentrations in women (median relative difference between serum IGFBP-1 concentrations after lycopene supplementation and after placebo, 21.7%). Serum IGFBP-2 concentrations were higher in both men and women after lycopene supplementation than after placebo, but to a lesser extent (mean relative difference 8.2%; 95% CI: 0.7%, 15.6% in men and 7.8%; 95% CI: -5.0%, 20.6% in women). Total IGF-I, IGF-II, and IGFBP-3 concentrations were not significantly altered by lycopene supplementation. CONCLUSIONS: This is the first study known to show that lycopene supplementation may increase circulating IGFBP-1 and IGFBP-2 concentrations. Because of high interindividual variations in IGFBP-1 and IGFBP-2 effects, these results should be confirmed in larger randomized intervention studies.     

Anthropometric and behavioral correlates of insulin-like growth factor I and insulin-like growth factor binding protein 3 in middle-aged Japanese men

High levels of plasma insulin-like growth factor I (IGF-I) and low levels of insulin-like growth factor binding protein 3 (IGFBP-3) have been related to increased risk of several cancers. Little is known about the behavioral determinants of these biologic markers. The authors examined the relation of anthropometric and behavioral factors to plasma concentrations of IGF-I and IGFBP-3 in a cross-sectional study of 616 Japanese men aged 45-55 years in 1995-1996. In univariate analyses, body mass index was strongly, positively associated with both IGF-I and IGFBP-3. The waist/hip ratio was also linearly related to IGF-I and IGFBP-3 up to the third quartile level. Height was weakly, positively associated with IGF-I and IGFBP-3. Smoking was inversely associated with IGF-I and IGFBP-3. Alcohol use was associated inversely with IGF-I and positively with IGFBP-3. Neither IGF-I nor IGFBP-3 was related to physical activity. Results of the multivariate analysis were essentially the same as those of the univariate analyses. The findings regarding body mass index are in contrast to those of previous studies showing null or inverse associations, and they suggest that the relation of body mass index to IGF-I or IGFBP-3 may vary among populations. The study also indicates that smoking and alcohol use might affect plasma IGF-I and IGFBP-3.     

Childhood diet and insulin-like growth factors in adulthood: 65-year follow-up of the Boyd Orr Cohort

OBJECTIVE: High levels of insulin-like growth factor-I (IGF-I) are associated with an increased cancer risk and reduce risk of diabetes and coronary heart disease. We investigated associations of diet in childhood, in particular energy intake, with the IGF system in adulthood to determine if IGF-I - disease associations could be linked to early nutrition. DESIGN: Retrospective cohort study. SETTING: Sixteen survey centres in England and Scotland that originally participated in the Carnegie (Boyd Orr) Survey of Diet and Health in Pre-War Britain, 1937-1939.Subjects:Seven hundred and twenty-eight participants (679 with complete data) in the Boyd Orr cohort. METHODS: Participants were originally surveyed between 1937 and 1939 (at median age 5.8 years; inter-quartile range: 2.9-9.6) and were followed up for 65 years. Dietary exposure in childhood was assessed from 7-day household food inventories. Outcomes are expressed as regression coefficients for the change in IGF per standard deviation increased childhood nutrient or food intake, as derived from levels of household consumption. RESULTS: In fully-adjusted models, energy-rich family diets in childhood were not associated with IGF-I (regression coefficient: 0.9 ng/ml; 95% confidence interval (CI): -1.8, 3.7), IGF-II, IGF binding proteins (IGFBP)-2 or IGFBP-3 in adulthood. IGF-I was associated inversely with childhood family-diets high in milk (-2.5 ng/ml; -5.1, 0.1; P=0.05) and positively with vegetable-rich diets (3.5 ng/ml; 0.9, 6.1; P=0.009). IGF-I was not associated with family diets rich in protein, carbohydrates, fats, calcium, meat or fruit. IGF-II, IGFBP-2 and IGFBP-3 were not related to childhood family diet. CONCLUSIONS: This study suggests that energy-rich family diets in childhood do not program the IGF system in adulthood. As childhood diet was based on household consumption, however, measurement error may obscure individual-level diet-IGF associations. The associations of milk- and vegetable-rich family diets in childhood with IGF-I could be chance findings, but nevertheless are consistent with recent publications and warrant further investigation.     

Isolated isoflavones do not affect the circulating insulin-like growth factor system in men at increased colorectal cancer risk

Epidemiological studies show that increased insulin-like growth factor (IGF)-I concentrations are related to increased colorectal cancer risk. A reduced colorectal cancer risk has been associated with isoflavones, which might affect the IGF-system because of their weak estrogenic activity. We conducted a randomized, placebo-controlled, double-blind crossover study to investigate the effect of an 8-wk isolated isoflavone supplementation (84 mg/d) on serum concentrations of total IGF-I, free IGF-I, total IGF-II, IGF binding protein (BP)-1, IGFBP-2, and IGFBP-3. Additionally, we investigated whether IGF-system component differences were related to concentrations of the more potent estrogenic isoflavone metabolite, equol. Our study population consisted of 37 men with a family history of colorectal cancer or a personal history of colorectal adenomas. Isoflavone supplementation did not significantly affect serum total IGF-I concentrations (relative difference between serum total IGF-I concentrations after isoflavone supplementation and after placebo: -1.3%, 95% CI -8.6 to 6.0%). Neither free IGF-I, nor total IGF-II, IGFBP-1, IGFBP-2, or IGFBP-3 concentrations were significantly altered. Interestingly, the change in serum IGF-I concentrations after isoflavone supplementation was negatively associated with serum equol concentrations (r=-0.49, P=0.002). In conclusion, isolated isoflavones did not affect the circulating IGF-system in a male high-risk population for colorectal cancer. However, to our knowledge, this is the first study that suggests isoflavones might have an IGF-I lowering effect in equol producers only. This underlines the importance of taking into account equol status in future isoflavone intervention studies.     

Insulin-like growth factor I,insulin-like growth factor binding protein 3, and urologic measures of benign prostatic hyperplasia

Laboratory studies suggest that insulin-like growth factor I (IGF-I) promotes prostatic growth. The authors evaluated the association between benign prostatic hyperplasia and IGF-I and its binding protein IGFBP-3 in community-dwelling men to determine whether this laboratory finding is manifest at the population level. Participants (n = 471) were Olmsted County, Minnesota, Caucasian males aged 40-79 years in 1990. Urologic measures were assessed from the International Prostate Symptom Score, peak urinary flow rates, prostate volume, and serum prostate-specific antigen (PSA), and serum IGF-I and IGFBP-3 levels were measured. After adjustment for age, the relative odds (odds ratios) of an abnormal urologic measure in men with high versus low serum IGF-I levels were 0.98 (95% confidence interval (CI): 0.66, 1.45) for a symptom score of >7, 1.14 (95% CI: 0.72, 1.80) for a peak urinary flow rate of <12 ml/second, 1.11 (95% CI: 0.72, 1.72) for a prostate volume of >30 ml, and 0.71 (95% CI: 0.46, 1.09) for a PSA level of >1.4 ng/ml. A low IGFBP-3 level was associated with an enlarged prostate (odds ratio = 1.72, 95% CI: 1.05, 2.82), after simultaneous adjustment for IGF-I and age, but not with other urologic measures. These data do not provide evidence for an association between benign prostatic hyperplasia and serum IGF-I.     

Moderate beer consumption and the risk of colorectal cancer

The relationship between beer consumption and the risk of colon and rectal cancer was considered in a case‐control study conducted in northern Italy. The study was based on 828 histologically confirmed incident cases of colon cancer, 498 of rectal cancer, and 2,024 controls in hospital for a wide spectrum of acute, nonneoplastic, nonalcohol‐related diseases. Beer drinking was reported by 6% of colon cancer cases, 7% of rectal cancer cases, and 10% of controls; regular beer drinkers (≥1 drinks/day) made up 2.6% of colon cancer cases, 3.2% of rectal cancer cases, and 4.1% of controls. Thus the multivariate relative risks (RR) for irregular drinkers were 0.6 [95% confidence interval (CI) 0.4–1.0] for colon and 0.7 (95% CI 0.4–1.2) for rectum. Corresponding values for regular drinkers were 0.7 (95% CI 0.4–1.2) for colon and 0.9 (95% CI 0.5–1.5) for rectal cancer. Despite the low frequency of beer drinking in this study, and hence its limited statistical power, the originality of the population in terms of colorectal cancer incidence, patterns of risk factor exposure, and the large dataset provide interesting and useful confirmation that moderate beer drinking is not associated with elevated colon or rectal cancer risk.     

A potential inverse association between insulin-like growth factor I and hypertension in a cross-sectional study

PURPOSE: Elevated circulating insulin-like growth factor I (IGF-I) levels increasingly are being implicated as a potential risk factor for the development of some cancers; however, relatively few epidemiologic studies have focused on potential relationships between circulating IGF-I levels and cardiovascular risk factors or cardiovascular disease. Hence, our objective is to examine relationships between IGF-I levels; body mass index (BMI); fasting insulin level; IGF binding protein 1 (IGFBP-1), IGFBP-2, and IGFBP-3 levels; and an array of traditional cardiovascular risk factors. METHODS: Our analysis included 715 men and women aged 30 to 62 years who participated in the V?sterbotten Intervention Project cohort. IGF-I and IGFBP-1, -2, and -3 were measured in stored plasma samples. Cardiovascular risk factors of interest included glucose level (fasting and 2-hour postload), lipid levels (total cholesterol, high-density lipoprotein cholesterol, and triglycerides), blood pressure (systolic and diastolic), and hypertension status. All presented results were adjusted for age, sex, and laboratory batch. RESULTS: IGF-I quartile was associated inversely with 2-hour glucose level and diastolic blood pressure. There was a stepwise inverse graded association between increasing IGF-I quartile and hypertension, with an odds ratio of 0.51 (95% confidence interval, 0.29-0.90) for hypertension comparing the fourth IGF-I quartile with the first. Further adjusting for BMI and IGFBP-3 level simultaneously strengthened the inverse association, with an odds ratio of 0.42 (95% confidence interval, 0.22-0.80) for hypertension comparing the fourth with the first IGF-I quartile. CONCLUSIONS: Contrary to positive associations between IGF-I levels and some cancers, our results suggest that IGF-I level may be related inversely to prevalent hypertension, a risk factor for cardiovascular disease.     

Vitamin D receptor gene polymorphisms, dietary promotion of insulin resistance, and colon and rectal cancer

Modifiable risk factors in colorectal cancer etiology and their interactions with genetic susceptibility are of particular interest. Functional vitamin D receptor (VDR) gene polymorphisms may influence carcinogenesis through modification of cell growth, protection from oxidative stress, cell-cell matrix effects, or insulin and insulin-like growth factor pathways. We investigated interactions between foods (dairy products, red and processed meat, and whole and refined grains) and dietary patterns (sucrose-to-fiber ratio and glycemic index) associated with insulin resistance with the FokI polymorphism of the VDR gene and colon and rectal cancer risk. Data (diet, anthropometrics, and lifestyle) and DNA came from case-control studies of colon (1,698 cases and 1,861 controls) and rectal cancer (752 cases and 960 controls) in northern California, Utah, and the Twin Cities metropolitan area, Minnesota (colon cancer study only).Unconditional logistic regression models were adjusted for smoking, race, sex, age, body mass index, physical activity, energy intake, dietary fiber, and calcium. The lowest colon cancer risk was observed with the Ff/ff FokI genotypes and a low sucrose-to-fiber ratio. Rectal cancer risk decreased with greater consumption of dairy products and increased with red or processed meat consumption and the FF genotype. Modifiable dietary risk factors may be differentially important among individuals by VDR genotype and may act through the insulin pathway to affect colon cancer risk and through fat, calcium, or other means to influence rectal cancer risk.     

Loss of the pregnancy-induced rise in cortisol concentrations in the ewe impairs the fetal insulin-like growth factor axis

Maternal cortisol levels increase during pregnancy. Although this change is important for optimal fetal growth, the mechanisms of the changes in growth remain unclear. The hypothesis examined was that alterations in maternal plasma cortisol concentrations are associated with changes in the fetal insulin-like growth factor (IGF) axis. Pregnant ewes in late gestation (115 ± 0.4 days) were studied: six control animals, five ewes given 1 mg kg(-1) day(-1) cortisol (high cortisol) and five adrenalectomised ewes given 0.5-0.6 mg kg(-1) day(-1) cortisol (low cortisol). Blood samples were taken throughout the experiment and at necropsy (130 ± 0.2 days) and fetal liver was frozen for mRNA analysis. Fetal IGF-I and insulin plasma concentrations were lower and insulin-like growth factor-binding protein-1 (IGFBP-1) concentrations were higher in the low cortisol group compared with those in the control group (P < 0.05). Fetal liver IGF-II and IGFBP-3 mRNA were decreased in low cortisol animals compared with controls (P < 0.05). There were no significant changes in these parameters in the high cortisol group, and there were no changes in fetal liver IGF-I, growth hormone receptor, IGF-I receptor, IGF-II receptor, IGFBP-1 or IGFBP-2 mRNA levels between the groups. These data suggest that reduced fetal IGF availability contributes to reduced fetal growth when maternal cortisol secretion is impaired, but not during exposure to moderate increases in cortisol.     

The effects of a high-fruit and -vegetable, high-fiber, low-fat dietary intervention on serum concentrations of insulin, glucose, IGF-I and IGFBP-3

OBJECTIVE: To determine the effects of dietary change on serum concentrations of insulin, glucose, IGF-I and IGFBP-3. SUBJECTS: From among participants in a randomized clinical trial of men and women without a history of diabetes who were 35 years old or older and who had at least one histologically confirmed colorectal adenoma removed during a qualifying colonoscopy within the 6 months before randomization, 750 subjects were selected for this analysis. METHODS: The authors analyzed fasting serum from 375 subjects with and 375 subjects without a recurrent polyp among participants in a randomized trial of a low-fat (20% of energy), high-fiber (18 g per 1000 kcals of energy intake) and high-fruit and -vegetable (5-8 servings per day) dietary intervention. RESULTS: After 4 years of follow-up, IGF-I concentration in the intervention group (N=248) declined by 8.86 ng/ml (initial mean of 133 ng/ml) and 7.74 ng/ml (initial mean value of 139 ng/ml) in the non-intervention group (N=502). Based on an unpaired t-test, these declines were both statistically significant, but the difference between groups for the decline in IGF-I (1.12 ng/ml ((95% confidence interval, -3.24 to 5.48)) was not. After 4 years, concentrations of IGFBP-3, insulin and glucose were not statistically different from values at baseline, and there were no differences in these serum measures between the intervention and control groups. In analysis restricted to lean (body mass index <25 kg/m(2)) subjects only, however, glucose concentrations in the intervention group decreased by 0.28 mmol/l, while they increased in the control group by 0.01 mmol/l (t-test for mean differences P=0.0003) over 4 years. CONCLUSIONS: A low-fat, high-fiber, high-fruit and -vegetable dietary intervention had minimal impact on serum concentrations of insulin, glucose, IGF-I and IGFBP-3 overall, but in lean subjects the intervention resulted in a significant reduction in serum glucose concentration.     

CYP1A1, cigarette smoking, and colon and rectal cancer

Cytochrome P-450 (CYP) is involved in the activation and metabolism of polycyclic aromatic hydrocarbons in tobacco products. The authors evaluated the association of two polymorphisms in the CYP1A1 gene--the noncoding Msp I polymorphism in the 3'-untranslated region and the Ile462Val polymorphism in exon 7--with colon and rectal cancer. The authors used data from two incident case-control studies of colon cancer (1,026 cases and 1,185 controls) and rectal cancer (820 cases and 1,036 controls) conducted in California and Utah (1991-2002). CYP1A1 genotype was not associated with colon or rectal cancer. Having GSTM1 present, a CYP1A1 variant allele, and the rapid-acetylator NAT2 imputed phenotype was associated with increased risk of colon cancer (odds ratio = 1.7, 95% confidence interval: 1.2, 2.3). Among men, the greatest colon cancer risk was observed for having any CYP1A1 variant allele and currently smoking (odds ratio = 2.5, 95% confidence interval: 1.3, 4.8; Wald chi(2)test: p < 0.01). Assessment of GSTM1 and CYP1A1 and rectal cancer in men showed a twofold elevation in risk for more than 20 pack-years of smoking, except among those with GSTM1 present who had a variant CYP1A1 allele. These data support the association between smoking and colon and rectal cancer. Smoking may have a greater impact on colorectal cancer risk based on CYP1A1 genotype; this might further be modified by GSTM1 for rectal cancer risk.     

Endogenous hormones and carotid atherosclerosis in elderly men

The aging process is characterized by a number of gradual changes in circulating hormone concentrations as well as a gradual increase in the degree of atherosclerosis. The authors studied whether serum hormone levels are related to atherosclerosis of the carotid artery in independently living, elderly men. In 1996, 403 men (aged 73-94 years) were randomly selected from the general population of Zoetermeer, the Netherlands. Carotid artery intima-media thickness was determined. Serum concentrations of testosterone; estrone; estradiol; dehydroepiandrosterone and dehydroepiandrosterone sulfate; insulin-like growth factor I (IGF-I) (total and free) and its binding proteins IGFBP-1, IGFBP-2, and IGFBP-3; and leptin were measured. After the authors adjusted for age, serum testosterone, estrone, and free IGF-I were inversely related to intima-media thickness. The strength of these relations was as powerful in subjects with as in those without prevalent cardiovascular disease. Serum estradiol; dehydroepiandrosterone sulfate; total IGF-I, IGFBP-1, IGFBP-2, and IGFBP-3; and leptin showed no association. These findings suggest that endogenous testosterone, estrone, and free IGF-I levels may play a protective role in the development of atherosclerosis in aging men.     

Enterotrophic effect of insulin-like growth factor-I but not growth hormone and localized expression of insulin-like growth factor-I, insulin-like growth factor binding protein-3 and -5 mRNAs in jejunum of parenterally fed rats

BACKGROUND: Administration of insulin-like growth factor (IGF)-I, but not growth hormone (GH), stimulates mucosal hyperplasia in surgically stressed rats with intestinal atrophy induced by hypocaloric total parenteral nutrition (TPN). Our aim was to characterize the basis for this disparity in enterotrophic action by assessing the relationships between stimulation of intestinal growth, nutritional adequacy, and localization of expression of IGF-I, insulin-like growth factor binding protein (IGFBP)-3 and IGFBP-5 mRNAs in jejunum. METHODS: Rats were maintained with TPN for 8 days and treated with IGF-I or GH and adequate nutrition for 5 days after recovery from surgery. Jejunal mass, morphology, and sucrase activity were assessed. Localization of expression of IGF-I, IGFBP-3, and IGFBP-5 mRNAs in jejunum was accomplished by in situ hybridization. RESULTS: Serum IGF-I and body weight gain were significantly increased by IGF-I or GH. Jejunal mucosal dry mass, morphology, and sucrase activity were improved with IGF-I but not GH. There were no differences in IGF-I mRNA. IGFBP-3 mRNA was localized in the lamina propria of the villi. IGF-I or GH stimulated IGFBP-3 expression. IGF-I strongly stimulated IGFBP-5 expression in the lamina propria and the muscularis and induced a twofold increase in IGFBP-5 mRNA based on RNase protection assay of intact jejunum total RNA. GH induced a modest increase in IGFBP-5 expression in the muscularis with no effect on intact jejunum total RNA. CONCLUSIONS: The GH resistance observed in the jejunal mucosa of TPN rats cannot be fully explained by inadequate nutrition. The expression of IGFBP-5 in the lamina propria suggests it may modulate the enterotrophic action of exogeneous IGF-I.     

促性腺激素释放激素类似物对特发性中枢性性早熟女童促生长素轴与生长速度的影响

目的 探讨促性腺激素释放激素类似物(GnRHa)治疗女童特发性中枢性性早熟(ICPP)对促生长素轴功能与生长速度关系的影响,为GnRHa治疗后出现的生长减速寻找新的治疗方法提供理论依据。方法 对接受GnRHa治疗的27例ICPP女童,观察在治疗开始以及治疗1年后其身高、骨龄、血清胰岛素样生长因子I(insulin-like growth factor-1,IGF-I)以及胰岛素生长因子结合蛋白3(IGFBP-3)等数据。依据她们的年龄分别计算身高、骨龄、IGF-I以及IGFBP3的标准差积分(SDS)。结果 ICPP患儿GnRHa治疗1年后,按实际年龄的身高SDS从1.03±0.74下降至0.83±0.73(P<0.001),按骨龄的身高SDS从-0.56±0.78增至-0.26±0.65(P<0.001)。治疗前后IGF-I SDS,IGFBP-3 SDS以及IGF-I/IGFBP-3差异无统计学意义(P>0.05)。与身高生长速度相关性最强的是提前的骨龄(R=0.291,P<0.05)。结论 ICPP患儿GnRHa治疗前后IGF-I、IGFBP-3均无明显改变,GnRHa可能是通过抑制IGF-I分泌轴之外的机制来影响身高生长速度。     

Energy balance and cancer: the role of insulin and insulin-like growth factor-I

Recent theories propose that a Western lifestyle may increase cancer risk through alterations in the metabolism of insulin and insulin-like growth factors (IGF: McKeown-Eyssen, 1994; Giovannucci, 1995; Kaaks, 19%; Werner & LeRoith, 1996). Insulin regulates energy metabolism, and increases the bioactivity of IGF-I, by enhancing its synthesis. and by decreasing several of its binding proteins (IGFBP; IGFBP-1 and -2). Insulin and IGF-I both stimulate anabolic processes as a function of available energy and elementary substrates (e.g. amino acids). The anabolic signals by insulin or IGF-I can promote tumour development by inhibiting apoptosis, and by stimulating cell proliferation. Furthermore, both insulin and IGF-I stimulate the synthesis of sex steroids, and inhibit the synthesis of sex hormone-binding globulin (SFIBG), a binding protein that regulates the bioavailability of circulating sex steroids to tissues. The present paper reviews epidemiological findings relating the risk of cancers of the colo-rectum, pancreas, breast, endometrium and prostate to body size (obesity, height) and physical activity, and discusses the relationships between obesity and physical activity and plasma levels of insulin, IGF-I and IGFBP. Subsequent sections review epidemiological findings relating cancer risk to indices of chronic hyperinsulinaemia, and to plasma levels of IGF-I and IGFBP. Conclusions are that chronic hyperinsulinaemia may be a cause of cancers of the colon, pancreas and endometrium, and also possibly of the breast. On the other hand, elevated plasma IGF-I, as total concentrations or relative to levels of IGFBP-3, appears to be related to an increased risk of prostate cancer, breast cancer in young women, and possibly cob-rectal cancer. For cancers of the endometrium, breast and prostate, these findings are discussed in the context of relationships between insulin and IGF-I and levels of bioavailable sex steroids.