Putative role of serum insulin-like growth factor–1 (IGF-1) and IGF binding protein-3 (IGFBP-3) levels in the development of prostate cancer in Arab men

Does milk intake promote prostate cancer initiation or progression via effects on insulin-like growth factors (IGFs)? A systematic review and meta-analysis

PURPOSE

To establish whether the association between milk intake and prostate cancer operates via the insulin-like growth factor (IGF) pathway (including IGF-I, IGF-II, IGFBP-1, IGFBP-2, and IGFBP-3).

METHODS

Systematic review, collating data from all relevant studies examining associations of milk with IGF, and those examining associations of IGF with prostate cancer risk and progression. Data were extracted from experimental and observational studies conducted in either humans or animals, and analyzed using meta-analysis where possible, with summary data presented otherwise.

RESULTS

One hundred and seventy-two studies met the inclusion criteria: 31 examining the milk-IGF relationship; 132 examining the IGF-prostate cancer relationship in humans; and 10 animal studies examining the IGF-prostate cancer relationship. There was moderate evidence that circulating IGF-I and IGFBP-3 increase with milk (and dairy protein) intake (an estimated standardized effect size of 0.10 SD increase in IGF-I and 0.05 SD in IGFBP-3 per 1 SD increase in milk intake). There was moderate evidence that prostate cancer risk increased with IGF-I (Random effects meta-analysis OR per SD increase in IGF-I 1.09; 95% CI 1.03, 1.16; n = 51 studies) and decreased with IGFBP-3 (OR 0.90; 0.83, 0.98; n = 39 studies), but not with other growth factors. The IGFBP-3 -202A/C single nucleotide polymorphism was positively associated with prostate cancer (pooled OR for A/C vs. AA = 1.22; 95% CI 0.84, 1.79; OR for C/C vs. AA = 1.51; 1.03, 2.21, n = 8 studies). No strong associations were observed for IGF-II, IGFBP-1 or IGFBP-2 with either milk intake or prostate cancer risk. There was little consistency within the data extracted from the small number of animal studies. There was additional evidence to suggest that the suppression of IGF-II can reduce tumor size, and contradictory evidence with regards to the effect of IGFBP-3 suppression on tumor progression.

CONCLUSION

IGF-I is a potential mechanism underlying the observed associations between milk intake and prostate cancer risk.

Pathological outcomes and agressiveness of low-risk prostate cancer in Northern African men

BACKGROUND

Northern African (NAf) men show a high incidence of advanced prostate cancer (PCa) at diagnosis. Several studies suggested the existence of ethnic differences in the PCa aggressiveness and this has led to some concerns related to the inclusion of some ethnic groups into active surveillance protocols.

OBJECTIVE

To evaluate pathological outcomes and aggressiveness of low risk PCa treated by radical prostatectomy in a NAf ethnic group.

SUBJECTS AND METHODS

Data of 147 NAfs, who underwent radical prostatectomy for low risk PCa diagnosed via a 12-core biopsy in 2 academic centers between 2011 and 2015, were reviewed retrospectively to assess rates of worse pathological outcomes defined as: Gleason score upgrade to at least 3+4, upstage to pT3a or higher or pN1, and positive surgical margins.

RESULTS

Overall significant upstage and/or upgrade occurred in 20.2% and positive surgical margins occured in18.3%. In multivariate logistic regression analysis, independent variables that predicted for upstage and/or upgrade or positive surgical margins in the entire cohort were: NCCN risk group (low risk>very low risk), advanced age>60 years, PSA>6ng/ml, PSA density≥0.15, more than 2 positive cores in biopsy, more than 50% cancer involvement in positive cores, clinical stage (T2a>T1c) and UCSF-CAPRA-S score>3.

CONCLUSIONS

Our study found that, at least pathologically, NAf men do not have more aggressive disease than Caucasians and African Americans in both low and very low risk PCa. Thus, we think that active surveillance is a suitable approach for selected patients since there is no definitive data that show a more aggressive natural history of PCa in NAf men.

Prostate Cancer in the Arab World: A View From the Inside

The rates of prostate cancer vary by more than 50-fold across different international populations. The aim of this review was to explore the differences in epidemiology and risk factors between the Middle Eastern Arab countries and some of the developed countries in Europe and North America. The age-standardized incidence rate of prostate cancer in the Arab countries is still lower than that in the Western countries, but is steadily increasing with time. Several factors come into play to explain this difference. There are health care systems-related factors such as the lack of good population-based registries, and population-related factors. The latter include the relatively young age structure in the Arab countries, lower reported androgen and prostate-specific antigen levels in Arab men, the effect of genetic differences on prostate cancer risk, the metabolic syndrome paradox, and the protective effect of the Mediterranean diet on a subset of the Arab population. In conclusion, the study of prostate cancer in the Arab world represents a challenge with the currently available cancer care systems and the increase in the burden of the disease. A multinational prospective study to investigate the epidemiology of prostate cancer in the Middle East, with specific attention to country/geographic variability along with a comparative analysis to that of the Western hemisphere is needed.

Relationship of insulin-like growth factor (IGF) binding protein-3 (IGFBP-3) gene polymorphism with the susceptibility to development of prostate cancer and influence on serum levels of IGF-I, and IGFBP-3

The bioavailability of IGF-I is controlled by the binding protein, IGF binding protein-3 (IGFBP-3). In addition, IGFBP-3 is a strong anti-proliferative protein that provokes apoptosis and inhibits cell proliferation in prostate cancer. We conducted this study to investigate the association between IGFBP-3 gene polymorphism and serum levels of IGF-I and IGFBP-3 and the incidence of prostate cancer (PCa) and benign prostatic hyperplasia (BPH). DNA isolation was performed in peripheral blood samples obtained from all participants. Required areas were amplified with polymerase chain reaction restriction fragment length polymorphism (PCR-RLFP) technique by using proper primers belonging to this gene area. We also measured serum IGF-I and IGFBP-3 levels. The IGFBP-3 -202 A/C polymorphism genotype frequencies showed a significant difference between PCa patients and controls (χ(2)=6.27, df=2.0, P=0.026), as well as between BPH patients and controls (χ(2)=11.57, df=4.0, P=0.014). The AA genotype frequency was significantly decreased in PCa and BPH patients compared to control group and the risk of PCa and BPH occurrence of this genotype was decreased accordingly (PCa; OR=0.28, 95% CI=0.17-0.44, P=0.0001; BPH: OR=0.48, 95% CI=0.29-0.77, P=0.001). Age-adjusted mean serum IGFBP-3 concentrations were highest in the individuals with the AA genotype and diminished significantly in a stepwise manner in the presence of 1 or 2 copies of the C allele (4577 ng/ml, 3929 ng/ml and 3349 ng/ml, respectively). Patients with PCa and BPH had lower serum IGF-1 (P=0.001, and P=0.01, respectively) and IGFBP-3 levels (P=0.001, and P=0.01, respectively) compared with controls. The AA genotype at IGFBP-3 gene polymorphism is associated with reduced risks of PCa and BPH. Both IGF-I and IGFBP-3 concentrations, are associated with modified risks of PCa and BPH.

Haplotype effect in the IGF1 promoter accounts for the association between microsatellite and serum IGF1 concentration

OBJECTIVE

Systemic insulin-like growth factor 1 (IGF1) level is an important risk factor for various diseases. The inter-individual variation of serum IGF1 is determined by environmental and genetic factors, which are attributed to a microsatellite in IGF1 promoter. However, the exact nature of the underlying regulatory elements accounting for this association has not been characterized. Here, we defined the haplotype patterns, including both SNPs and the microsatellite, in the Chinese population, and investigated their regulatory effect on serum IGF1 level. This is the first study in which haplotype patterns of the microsatellite and SNPs in the IGF1 promoter are examined together.

METHODS

The linkage disequilibrium (LD) patterns of IGF1 were examined using tagSNPs of the IGF1 regulatory region. The microsatellite, three tagSNPs and haplotypes were correlated with serum IGF1 concentration in 450 normal premenopausal Chinese women.

RESULTS

Common alleles of the microsatellite were in strong LD with the three tagSNPs and were associated with particular haplotypes composed of SNPs. Neither the CA repeat number nor SNPs alone showed a robust association with serum IGF1 concentration. On the other hand, the haplotype T-19-A-T was significantly associated with serum IGF1 level.

CONCLUSION

No association was found between SNPs and microsatellite alone. However, the haplotype showed better correlation with serum IGF1 level. The results indicate that the previously observed correlation with microsatellite was because of a haplotype effect in the IGF1 promoter. Microsatellite or tagSNPs alone are not the primary regulatory elements of IGF1 expression. The exact regulatory genetic variant needs to be defined by functional genetic studies.

Insulin-like growth factor-I (IGF-I) serum concentrations in healthy children and adolescents: relationship to level of contamination by DDT-derivative pesticides

CONTEXT

Serum levels of Insulin-like growth factor I (IGF-I) play a critical role in children growth and in the pathogenesis of several diseases. In addition, recent studies suggest that DDT-derivative organochlorine pesticides (OC-DDTs) could influence IGF levels in human beings.

OBJECTIVE AND DESIGN

Because it has been suggested that IGF-I peak levels at puberty could determine IGF-I levels in adulthood, we developed a cross-sectional study of the potential association between serum levels of OC-DDTs and IGF system in 160 serum samples from young people (81 boys and 79 girls) living in the Canary Islands (Spain).

RESULTS

Multivariate tests were used adjusting for confounding variables (age, height, and weight) and stratifying by gender and age: IGF-I serum levels were significantly lower in pre-pubertal male children (6-15years) who showed detectable values of p,p'-DDE, and p,p'-DDD than in pre-pubertal male children with undetectable levels of these OC-DDTs-metabolites (p=0.023 and p=0.049, respectively). In addition, in this multivariate model, a non-linear dose-response curve was observed between Total DDT body burden (sum of the three DDT-derivatives measured: p,p'-DDT, p,p'-DDE, and p,p'-DDD) and IGF-I in pre-pubertal male children (6-15years; p=0.043).

CONCLUSION

These findings suggest that OC-DDTs could modulate the IGF-system in a way that is highly influenced by gender and age. Improvements in our understanding of exogenous determinants of the IGF-system may provide new insights into the role played by environmental contaminants in IGF-related diseases.

Circulating insulin-like growth factor peptides and prostate cancer risk: a systematic review and meta-analysis

Insulin-like growth factors (IGF-I, IGF-II) and their binding proteins (IGFBP-1-6) play a key role in cell proliferation, differentiation and apoptosis, suggesting possible involvement in carcinogenesis. Several epidemiological studies show associations of IGFs with prostate cancer. We searched the published literature for all studies relating levels of IGFs or IGFBPs with prostate cancer. We performed random effects meta-analysis to calculate summary odds ratios. The number of studies (prostate cancer cases) included in each meta-analysis were 42 (7,481) IGF-I; 10 (923) IGF-II; 3 (485) IGFBP-1; 5 (577) IGFBP-2; 29 (6,541) IGFBP-3 and 11 (3,545) IGF-1:IGFBP-3 ratio. The pooled odds ratios (95% confidence intervals) per standard deviation increase in peptide were: IGF-I, OR = 1.21 (1.07, 1.36); IGF-II, OR = 1.17 (0.93, 1.47); IGFBP-1, OR = 1.21 (0.62, 2.33); IGFBP-2, OR = 1.18 (0.90, 1.54); IGFBP-3, OR = 0.88 (0.79, 0.98); IGFI:IGFBP-3 ratio, OR = 1.10 (0.97, 1.24). For all exposures, there was substantial heterogeneity (all I(2) > 75%), partly explained by study design: the magnitude of associations was smaller in prospective vs. retrospective studies, and for IGFBP-3, the inverse association with prostate cancer risk was seen in retrospective but not prospective studies. There was weak evidence that associations of IGF-I and IGFBP-3 with prostate cancer were stronger for advanced disease. Our meta-analysis confirms that raised circulating lGF-I is positively associated with prostate cancer risk. Associations between IGFBP-3 and prostate cancer were inconsistent, and there was little evidence for a role of IGF-II, IGFBP-1 or IGFBP-2 in prostate cancer risk.

Insulin-Like Growth Factor (IGF) family and prostate cancer

There is abundant in vitro, animal and epidemiologic evidence to suggest that the Insulin-Like Growth Factor (IGF) family is a multi-component network of molecules which is involved in the regulation of both physiological and pathological growth processes in prostate. The IGF family plays a key role in cellular metabolism, differentiation, proliferation, transformation and apoptosis, during normal development and malignant growth. This family also seem essential in prostate cancer bone metastases, angiogenesis and androgen-independent progression. Therapeutic alternatives in men with progressive prostate cancer after androgen ablation are very limited. More effective therapies are needed for these patients. Pharmacologic interventions targeting the IGF family are being devised. Such strategies include reduction of IGF-I levels (growth hormone-releasing hormone antagonists, somatostatin analogs), reduction of functional IGF-I receptor levels (antisense oligonucleotides, small interfering RNA), inhibition of IGF-IR and its signalling (monoclonal antibodies, small-molecule tyrosine kinase inhibitors) and Insulin-Like Growth Factor Binding Proteins.