Serum levels of insulin-like growth factor I (IGF-I), IGF-II, IGF-binding protein-3, and prostate-specific antigen as predictors of clinical prostate cancer

Drug resistance in metastatic castration-resistant prostate cancer: an update on the status quo

Prostate cancer (PCa) is a leading cause of cancer-related morbidity and mortality in men globally. Despite improvements in the diagnosis and treatment of PCa, a significant proportion of patients with high-risk localized disease and all patients with advanced disease at diagnosis will experience progression to metastatic castration-resistant prostate cancer (mCRPC). Multiple drugs are now approved as the standard of care treatments for patients with mCRPC that have been shown to prolong survival. Although the majority of patients will respond initially, primary and secondary resistance to these therapies make mCRPC an incurable disease. Several molecular mechanisms underlie the development of mCRPC, with the androgen receptor (AR) axis being the main driver as well as the key drug target. Understanding resistance mechanisms is crucial for discovering novel therapeutic strategies to delay or reverse the progression of the disease. In this review, we address the diverse mechanisms of drug resistance in mCRPC. In addition, we shed light on emerging targeted therapies currently being tested in clinical trials with promising potential to overcome mCRPC-drug resistance.

Circulating insulin-like growth factor-I and risk of 25 common conditions: outcome-wide analyses in the UK Biobank study

While there is strong epidemiological evidence that circulating insulin-like growth factor-I (IGF-I) is associated with a higher risk of several cancers, little is known about its association with non-cancer outcomes. We investigated associations of circulating IGF-I with risk of 25 common conditions, other than cancer, in a large British cohort. Study participants were 318,749 middle-aged adults enrolled in the UK Biobank Study. Serum IGF-I concentration was measured in samples collected at baseline (2006-2010), and re-measured in 12,334 participants after an average of 4.3 years. We followed-up participants over an average of 11.5 years by linking to hospital admissions and mortality registries. Multivariable-adjusted Cox regressions estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between circulating IGF-I and 25 common conditions, using the repeated IGF-I measurements to correct for regression dilution bias. After correction for multiple testing (P < 0.002), IGF-I was positively associated with carpal tunnel syndrome (HR per 5 nmol/l higher concentration = 1.12, 95% CI 1.08-1.16), and inversely associated with varicose veins (0.90, 0.85-0.95), cataracts (0.97, 0.95-0.99), diabetes (0.92, 0.90-0.95), and iron deficiency anaemia (0.90, 0.86-0.93). The associations for cataracts and diabetes attenuated when restricted to cases diagnosed after five or more years of follow-up, suggesting that these associations were likely affected by reverse causality. Higher IGF-I concentration might be associated with the risk for several conditions, but genetic studies are needed to clarify which associations may be causal.

Dietary energy density and risk of prostate cancer: (A case-control study)

OBJECTIVE

Some observational studies investigated the association between dietary energy density (DED) and risk of cancers with inconstant results. In addition, there is no study on such association among patients with prostate cancer (PC). The present study was performed to evaluate the association between dietary energy density (DED) and PC risk.

METHODS

In this case-control study, one hundred and twenty-five participants were enrolled (62 cases and 63 controls). Dietary intakes were assessed using 160-item semi-quantitative food frequency questionnaire. In addition, demographic characteristics were collected using a general questionnaire and anthropometric indices were measured based on the available guidelines. The association between DED and PC risk was evaluated using multivariable logistic regression.

RESULTS

The results showed that higher DED score was associated with increased risk of PC (OR = 2.59; 95% CI= (1.24-5.40)). Interestingly, after adjusting for potential confounders ((smoking, physical activity, energy intake, education, ethnicity, job, anti-hyperlipidemic drugs, antihypertensive drugs, and aspirin) the results remained significant (OR = 2.87; 95% CI= (1.17-7.05)).

CONCLUSION

Our findings suggest that DED may increase the risk of PC. However, more prospective studies are warranted to confirm these results.

Diabetes and Cancer: Metabolic Association, Therapeutic Challenges, and the Role of Natural Products

Cancer is considered the second leading cause of death worldwide and in 2018 it was responsible for approximately 9.6 million deaths. Globally, about one in six deaths are caused by cancer. A strong correlation was found between diabetes mellitus and carcinogenesis with the most evident correlation was with type 2 diabetes mellitus (T2DM). Research has proven that elevated blood glucose levels take part in cell proliferation and cancer cell progression. However, limited studies were conducted to evaluate the efficiency of conventional therapies in diabetic cancer patients. In this review, the correlation between cancer and diabetes will be discussed and the mechanisms by which the two diseases interact with each other, as well as the therapeutics challenges in treating patients with diabetes and cancer with possible solutions to overcome these challenges. Natural products targeting both diseases were discussed with detailed mechanisms of action. This review will provide a solid base for researchers and physicians to test natural products as adjuvant alternative therapies to treat cancer in diabetic patients.

Obesity, Inflammation, and Advanced Prostate Cancer

Obesity is associated with high-grade and advanced prostate cancer. While this association may be multi-factorial, studies suggest that obesity-induced inflammation may play a role in the progression of advanced prostate cancer. The microenvironment associated with obesity increases growth factors and pro-inflammatory cytokines which have been implicated mechanistically to promote invasion, metastasis, and androgen-independent growth. This review summarizes recent findings related to obesity-induced inflammation which may be the link to advanced prostate cancer. In addition, this review while introduce novel targets to mitigate prostate cancer metastasis to the bone. Specific emphasis will be placed on the role of the pro-inflammatory cytokines interleukin (IL)-6, tumor necrosis factor (TNF)α, and IL-1β.

IGF-1 and hyperglycaemia-induced FOXA1 and IGFBP-2 affect epithelial to mesenchymal transition in prostate epithelial cells

Localized prostate cancer (PCa) is a manageable disease but for most men with metastatic disease, it is often fatal. A western diet has been linked with PCa progression and hyperglycaemia has been associated with the risk of lethal and fatal prostate cancer. Using PCa cell lines, we examined the impact of IGF-I and glucose on markers of epithelial-to-mesenchymal transition (EMT), migration and invasion. We examined the underlying mechanisms using cell lines and tumour tissue samples. IGF-I had differential effects on the process of EMT: inhibiting in normal and promoting in cancer cells, whereas hyperglycamia alone had a stimulatory effect in both. These effects were independent of IGF and in both cases, hyperglycaemia induced an increase IGFBP-2(tumour promoter) and FOXA1. A positive correlation existed between levels of IGFBP-2 and FOXA1 in benign and cancerous prostate tissue samples and in vitro and in vivo data indicated that FOXA1 strongly interacted with the IGFBP-2 gene in normal prostate epithelial cells that was associated with a negative regulation of IGFBP-2, whereas in cancer cells the level of FOXA1 associating with the IGFBP-2 gene was minimal, suggesting loss of this negative regulation. IGF-I and hyperglycaemia-induced FOXA1/IGFBP-2 play important roles in EMT.

Advances in insulin-like growth factor biology and -directed cancer therapeutics

The insulin and insulin-like growth factor (IGF) family of proteins are part of a complex network that regulates cell proliferation and survival. While this system is undoubtedly important in prenatal development and postnatal cell growth, members of this family have been implicated in several different cancer types. Increased circulating insulin and IGF ligands have been linked to increased risk of cancer incidence. This observation has led to targeting the IGF system as a therapeutic strategy in a number of cancers. This chapter aims to describe the well-characterized biology of the IGF1R system, outline the rationale for targeting this system in cancer, summarize the clinical data as it stands, and discuss where we can go from here.

Dietary Carcinogens and DNA Adducts in Prostate Cancer

Prostate cancer (PC) is the most commonly diagnosed non-cutaneous cancer and the second leading cause of cancer-related to death in men. The major risk factors for PC are age, family history, and African American ethnicity. Epidemiological studies have reported large geographical variations in PC incidence and mortality, and thus lifestyle and dietary factors influence PC risk. High fat diet, dairy products, alcohol and red meats, are considered as risk factors for PC. This book chapter provides a comprehensive, literature-based review on dietary factors and their molecular mechanisms of prostate carcinogenesis. A large portion of our knowledge is based on epidemiological studies where dietary factors such as cancer promoting agents, including high-fat, dairy products, alcohol, and cancer-initiating genotoxicants formed in cooked meats have been evaluated for PC risk. However, the precise mechanisms in the etiology of PC development remain uncertain. Additional animal and human cell-based studies are required to further our understandings of risk factors involved in PC etiology. Specific biomarkers of chemical exposures and DNA damage in the prostate can provide evidence of cancer-causing agents in the prostate. Collectively, these studies can improve public health research, nutritional education and chemoprevention strategies.

Treatment Options in Hormone-refractory Metastatic Prostate Carcinoma

Prostate cancer represents one of the most important health problems in industrialized countries. It is the second leading cause of cancer-related death in the United States. Therapeutic options are different according to the stage of the disease at the diagnosis. Patients with localized disease may be treated with surgery or radiation, whereas the treatment for patients with a metastatic disease is purely palliative. Hormonal treatment represents the standard therapy for stage IV prostate cancer, but patients ultimately become unresponsive to androgen ablation and are classified as hormone-refractory prostate cancer patients. The molecular mechanisms involved in progression in hormone resistance are characterized by mutations, down and up-regulation in the androgen receptor gene, mutations in p53 and over-expression of Bcl2 and other alterations in genes and in gene expression. The important thing is that we understand these mechanisms to define potential therapeutic agents for the treatment of hormone-refractory prostate cancer patients. Conventional options for patients with hormone-refractory prostate cancer include secondary hormone therapy, radiotherapy and cytotoxic chemotherapy. The commonest antineoplastic agents are mitoxantrone, estramustine and taxanes. Despite an improvement In the palliative benefit, none of these agents has demonstrated a beneficial impact on the overall survival of patients. Therefore, there is no standard therapy for these patients, thus we need new approaches which should be studied in clinical trials. The evaluation and incorporation of new agents into current treatment regimens could have a role in the treatment of hormone-refractory prostate cancer, but their efficacy has not yet been demonstrated.

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.

Interactions of the Insulin-Like Growth Factor Axis and Vitamin D in Prostate Cancer Risk in the Prostate Cancer Prevention Trial

Some, but not all, epidemiologic studies report an association between vitamin D and prostate cancer risk. The inconsistent findings might be explained in the context of modification by members of the insulin-like growth factor (IGF) axis. Data and specimens for this nested case-control study (n = 1695 cases and n = 1682 controls) are from the Prostate Cancer Prevention Trial (PCPT). Baseline serum samples were assayed for 25(OH)D, IGF-1, IGF-2, IGFBP-2, IGFBP-3, and the ratio of IGF1:BP3, along with insulin-related markers c-peptide and leptin. The presence of prostate cancer was assessed by prostate biopsy. Multivariate logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CIs) for prostate cancer risk. There were no interactions between serum 25(OH)D and IGF analytes in relation to prostate cancer risk when PCPT treatment arms were combined. In the placebo arm, above median serum 25(OH)D levels were associated with increased risk of prostate cancer among men with higher IGF-2 (OR:1.33, 95% CI: 1.00–1.65), with a significant interaction between 25(OH)D and treatment arm (P_interaction = 0.04). Additionally, there was an interaction between treatment arm and serum IGFBP-3 (P_interaction = 0.03). Higher serum 25(OH)D may increase risk of prostate cancer in the presence of higher circulating IGF-2.

Dissecting major signaling pathways in prostate cancer development and progression: Mechanisms and novel therapeutic targets

Prostate cancer (PCa) is the most frequently diagnosed non-cutaneous malignancy and leading cause of cancer mortality in men. At the initial stages, prostate cancer is dependent upon androgens for their growth and hence effectively combated by androgen deprivation therapy (ADT). However, most patients eventually recur with an androgen deprivation-resistant phenotype, referred to as castration-resistant prostate cancer (CRPC), a more aggressive form for which there is no effective therapy presently available. The current review is an attempt to cover and establish an understanding of some major signaling pathways implicated in prostate cancer development and castration-resistance, besides addressing therapeutic strategies that targets the key signaling mechanisms.

Evaluation of Insulin-like Growth Factor-1 and Insulin-like Growth Factor Binding Protein-3 Expression Levels in Patients with Chronic Lymphocytic Leukemia

OBJECTIVE

Chronic lymphocytic leukemia (CLL) is a disease of nonproliferating and mature-appearing B lymphocytes. Insulin-like growth factor-1 (IGF-1) is a small peptide hormone and has mitogenic and antiapoptotic effects, and insulin-like growth factor binding protein-3 (IGFBP-3) has antiproliferative effects on cells. In this study, we investigated plasma levels of both IGF-1 and IGFBP-3 in patients with CLL compared with controls, and we compared these plasma levels according to prognostic factors.

MATERIALS AND METHODS

Patients with newly diagnosed CLL who were being followed at the Haseki Training and Research Hospital, İstanbul, Turkey, and volunteers were included in this study. Patients were stratified according to the Rai staging system. Statistical analysis was conducted using SPSS 17.0 for Windows.

RESULTS

Forty-three patients [16 women (37%) and 27 men (63%)] were enrolled in this study. Twenty-one volunteers (11 women, 10 men) were included in the control group. The median age of the patients was 65±9 years (range: 18-63 years), and subjects in the control group were 68±8 years old (range: 18-63 years). Even though the plasma levels of IGF-1 were higher and those of IGFBP-3 were lower and the ratio of IGF-I/IGFBP-3 was higher in comparison with the control group, these differences were not statistically significant (p>0.05). In the study group, IGF-1 levels appeared to be increased in parallel to more advanced Rai stages. There were no significant differences between the other groups (p=0.105).

CONCLUSION

Plasma IGF-I levels were found higher in patients than in the control group and plasma IGFBP-3 levels were lower; however, neither result was statistically significant. Plasma IGF level increment was observed in concordance with Rai staging. These results prompted us to think that plasma IGF-1 levels in CLL patients are correlated with tumor burden and Rai staging and therefore could be a valuable prognostic factor. Further comprehensive studies are required to support our results.

Evaluating serum insulin-like growth factor 1 and insulin-like growth factor binding protein 3 as markers in prostate cancer diagnosis

BACKGROUND

Prostate-specific antigen (PSA) lacks specificity and sensitivity in discriminating prostate cancer (PCa) from benign prostatic hyperplasia (BPH) when the total PSA (tPSA) level is between 4 and 10 ng/mL. It remains to be investigated if additional tumor-associated molecules may improve the PCa diagnostic accuracy. The aim of the present study was to investigate whether serum levels of insulin-like growth factor 1 (IGF1), insulin-like growth factor binding protein 3 (IGFBP3) and their combinations with PSA may enhance the diagnosis of PCa.

METHODS

Serum tPSA and free PSA (fPSA) levels were measured using an automated chemiluminescence-based method. IGF1 and IGFBP3 levels were evaluated by radioimmunoassays in a prospectively and consecutively enrolled subset of 149 patients with tPSA ≤10 ng/mL made up of patients with benign prostatic hyperplasia (BPH; n = 113) and PCa (n = 36).

RESULTS

IGF1 and IGFBP3 serum levels did not significantly differ between the PCa and BPH groups. No important correlation was found between the IGF molecules and PSA isoforms in both groups. Statistical analysis of the combination of markers indicated that only the free/total PSA ratio (f/tPSA%) was informative and independent in predicting the presence of PCa, considering that for high values of this percentage (17%) the probability of finding PCa decreased. Receiver operating characteristics areas under the curve (AUC) for IGF1 and IGFBP3 were not informative (AUC ~0.5 in both cases) contrary to the AUC for f/tPSA% (AUC = 0.689, p = 0.0002).

CONCLUSIONS

The present study showed that neither IGF1 and IGFBP3 alone nor in combination with PSA enhance the diagnostic performance of PSA in PCa.

Polymorphism in IGFBP3 gene is associated with prostate cancer risk: an updated meta-analysis

OBJECTIVE

Insulin-like growth factor-binding protein-3 (IGFBP3) is the major protein that binds with insulin-like growth factor-1 (IGF-1) and is considered to be involved in the development and progression of various cancers. We aimed to examine the association between prostate cancer (PCa) and the IGFBP3 gene-202A/C polymorphism.

METHODS

A comprehensive search within PubMed, EMBASE, and Cochrane Library was conducted to identify all case-control studies up to October 30, 2015, for a meta-analysis. Pooled odds ratios (ORs) and the 95% confidence intervals (CIs) were calculated using the fixed or random effects model.

RESULTS

Eighteen studies including 10,538 cases and 10,078 controls were identified. Overall, the CC genotype of IGFBP3-202A/C polymorphism was associated with increased risk of PCa in homozygote comparison (CC vs AA - OR =1.16, 95% CI: 1.08-1.25) and in recessive model (CC vs AA+AC - OR =1.11, 95% CI: 1.04-1.17). In dominant model, the CC/AC genotypes also implicated an increased risk of PCa (CC+AC vs AA - OR =1.11, 95% CI: 1.05-1.19). The C allele of IGFBP3-202A/C polymorphism was the risk allele for PCa relative to the A allele (OR =1.09, 95% CI: 1.05-1.14). Further stratification analysis revealed that the association between -202A/C polymorphism and PCa risk among Caucasians, but not in other ethnicities, was statistically significant (recessive model, OR =1.10, 95% CI: 1.02-1.19). In addition, the IGFBP3-202A/C polymorphism was associated with PCa risk in both population-based and hospital-based studies in homozygote comparison, recessive model, and allele model.

CONCLUSION

Our meta-analysis indicates that the IGFBP3-202A/C polymorphism is associated with the risk of PCa, particularly in Caucasians, with the C allele being the risk allele for PCa.

A Meta-analysis of Individual Participant Data Reveals an Association between Circulating Levels of IGF-I and Prostate Cancer Risk

The role of insulin-like growth factors (IGF) in prostate cancer development is not fully understood. To investigate the association between circulating concentrations of IGFs (IGF-I, IGF-II, IGFBP-1, IGFBP-2, and IGFBP-3) and prostate cancer risk, we pooled individual participant data from 17 prospective and two cross-sectional studies, including up to 10,554 prostate cancer cases and 13,618 control participants. Conditional logistic regression was used to estimate the ORs for prostate cancer based on the study-specific fifth of each analyte. Overall, IGF-I, IGF-II, IGFBP-2, and IGFBP-3 concentrations were positively associated with prostate cancer risk (Ptrend all ≤ 0.005), and IGFBP-1 was inversely associated weakly with risk (Ptrend = 0.05). However, heterogeneity between the prospective and cross-sectional studies was evident (Pheterogeneity = 0.03), unless the analyses were restricted to prospective studies (with the exception of IGF-II, Pheterogeneity = 0.02). For prospective studies, the OR for men in the highest versus the lowest fifth of each analyte was 1.29 (95% confidence interval, 1.16-1.43) for IGF-I, 0.81 (0.68-0.96) for IGFBP-1, and 1.25 (1.12-1.40) for IGFBP-3. These associations did not differ significantly by time-to-diagnosis or tumor stage or grade. After mutual adjustment for each of the other analytes, only IGF-I remained associated with risk. Our collaborative study represents the largest pooled analysis of the relationship between prostate cancer risk and circulating concentrations of IGF-I, providing strong evidence that IGF-I is highly likely to be involved in prostate cancer development. Cancer Res; 76(8); 2288-300. ©2016 AACR.

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.

Insulin-like growth factor receptor-1 (IGF-IR) as a target for prostate cancer therapy

Prostate cancer is the most commonly diagnosed cancer in men and is the second leading cause of cancer-related deaths in men each year. Androgen deprivation therapy is and has been the gold standard of care for advanced or metastatic prostate cancer for decades. While this treatment strategy initially shows benefit, eventually tumors recur as castration-resistant prostate cancer for which there are limited treatment options with only modest survival benefit. Upregulation of the insulin-like growth factor receptor type I (IGF-IR) signaling axis has been shown to drive the survival of prostate cancer cells in many studies. As many IGF-IR blockades have been developed, few have been tested preclinically and even fewer have entered clinical trials for prostate cancer therapy. In this review, we will update the most recent preclinical and clinical studies of IGF-IR therapy for prostate cancer. We will also discuss the challenges for IGF-IR targeted therapies to achieve clinical benefit for prostate cancer.

The Role of the Insulin/IGF System in Cancer: Lessons Learned from Clinical Trials and the Energy Balance-Cancer Link

Numerous epidemiological and pre-clinical studies have demonstrated that the insulin/insulin-like growth factor (IGF) system plays a key role in the development and progression of several types of cancer. Insulin/IGF signaling, in cooperation with chronic low-grade inflammation, is also an important contributor to the cancer-promoting effects of obesity. However, clinical trials for drugs targeting different components of this system have produced largely disappointing results, possibly due to the lack of predictive biomarker use and problems with the design of combination therapy regimens. With careful attention to the identification of likely patient responders and optimal drug combinations, the outcome of future trials may be improved. Given that insulin/IGF signaling is known to contribute to obesity-associated cancer, further investigation regarding the efficacy of drugs targeting this system and its downstream effectors in the obese patient population is warranted.

EGFR and IGF-1R in regulation of prostate cancer cell phenotype and polarity: opposing functions and modulation by T-cadherin

T-cadherin is an atypical glycosylphosphatidylinsoitol-anchored member of the cadherin superfamily of adhesion molecules. We found that T-cadherin overexpression in malignant (DU145) and benign (BPH-1) prostatic epithelial cell lines or silencing in the BPH-1 cell line, respectively, promoted or inhibited migration and spheroid invasion in collagen I gel and Matrigel. T-cadherin-dependent effects were associated with changes in cell phenotype: overexpression caused cell dissemination and loss of polarity evaluated by relative positioning of the Golgi/nuclei in cell groups, whereas silencing caused formation of compact polarized epithelial-like clusters. Epidermal growth factor receptor (EGFR) and IGF factor-1 receptor (IGF-1R) were identified as mediators of T-cadherin effects. These receptors per se had opposing influences on cell phenotype. EGFR activation with EGF or IGF-1R inhibition with NVP-AEW541 promoted dissemination, invasion, and polarity loss. Conversely, inhibition of EGFR with gefitinib or activation of IGF-1R with IGF-1 rescued epithelial morphology and decreased invasion. T-cadherin silencing enhanced both EGFR and IGF-1R phosphorylation, yet converted cells to the morphology typical for activated IGF-1R. T-cadherin effects were sensitive to modulation of EGFR or IGF-1R activity, suggesting direct involvement of both receptors. We conclude that T-cadherin regulates prostate cancer cell behavior by tuning the balance in EGFR/IGF-1R activity and enhancing the impact of IGF-1R.

Investigation of insulin resistance gene polymorphisms in patients with differentiated thyroid cancer

We aimed to investigate insulin receptor substrate-1 (IRS-1), insulin receptor substrate-2 (IRS-2), insulin-like growth factor binding protein-3 (IGFBP-3) genotypes, which are thought to be involved in the pathogenesis of many solid tumors and have thus far not been studied in patients with differentiated thyroid cancer (DTC). The study consisted of 93 patients diagnosed with DTC (79 females, 14 males) and 111 healthy control subjects (63 females, 48 males). The anthropometric measurements, lipid profiles, thyroid function tests and homeostatic model assessment (HOMA) as an indicator of insulin resistance (IR) of all patients were recorded. In addition IRS-1, IRS-2 and IGFBP-3 gene polymorphisms were determined by using polymerase chain reaction and restriction fragment length polymorphism. Hardy-Weinberg equilibrium was tested for each gene polymorphisms, and genetic effects were evaluated by the Chi Square test and multiple logistic regression. Homeostasis model assessment of insulin resistance (HOMA-IR), body mass index, waist circumference and serum total cholesterol levels were significantly higher in patients with DTC than in the control group. There was no difference between the two groups with respect to IRS-1, IRS-2 and IGFBP-3 gene polymorphisms. In addition, these gene polymorphisms were found to have no effect on lymph node metastases or tumor staging. While, obesity and increased HOMA-IR may be risk factors in DTC development, we suggest that IRS-1, IRS-2 and IGFBP-3 gene polymorphisms do not play an important role in pathogenesis of DTC.

Androgen receptor splice variant AR3 promotes prostate cancer via modulating expression of autocrine/paracrine factors

Deregulation of androgen receptor (AR) splice variants has been implicated to play a role in prostate cancer development and progression. To understand their functions in prostate, we established a transgenic mouse model (AR3Tg) with targeted expression of the constitutively active and androgen-independent AR splice variant AR3 (a.k.a. AR-V7) in prostate epithelium. We found that overexpression of AR3 modulates expression of a number of tumor-promoting autocrine/paracrine growth factors (including Tgfβ2 and Igf1) and expands prostatic progenitor cell population, leading to development of prostatic intraepithelial neoplasia. In addition, we showed that some epithelial-mesenchymal transition-associated genes are up-regulated in AR3Tg prostates, suggesting that AR3 may antagonize AR activity and halt the differentiation process driven by AR and androgen. This notion is supported by our observations that the number of Ck5(+)/Ck8(+) intermediate cells is increased in AR3Tg prostates after castration, and expression of AR3 transgene in these intermediate cells compromises prostate epithelium regeneration upon androgen replacement. Our results demonstrate that AR3 is a driver of prostate cancer, at least in part, through modulating multiple tumor-promoting autocrine/paracrine factors.

Protein expression of PTEN, insulin-like growth factor I receptor (IGF-IR), and lethal prostate cancer: a prospective study

BACKGROUND

Loss of PTEN has been shown to be associated with aggressive behavior of prostate cancer. It is less clear that loss of PTEN also increases the risk of cancer mortality. We investigated the association between PTEN expression and prostate cancer mortality and the potential effect modification by IGF-IR, a direct activator of the phosphoinositide-3-kinase (PI3K) pathway.

METHODS

Protein expression in tumor was evaluated using tumor tissues obtained from 805 participants of the Physicians' Health and the Health Professionals Follow-up studies who were diagnosed with prostate cancer and underwent radical prostatectomy. Proportional hazard models were used to assess PTEN expression and its interaction with IGF-IR, in relation to lethal prostate cancer (cancer-specific death or distant metastases).

RESULTS

Low PTEN expression was associated with an increased risk of lethal prostate cancer [HR, 1.7; 95% confidence interval (CI), 0.98-3.2; Ptrend = 0.04]. The association was attenuated after adjustment for Gleason grade, tumor stage, and prostate-specific antigen (PSA) at diagnosis. A significant negative interaction between PTEN and IGF-IR was found (Pinteraction = 0.03). Either reduction in PTEN or increase in IGF-IR expression was sufficient to worsen prognosis. Models including PTEN and IGF-IR expression offer additional predicting power to prostate cancer survival, compared to those only including demographic and clinical factors.

CONCLUSIONS

Low PTEN protein expression significantly increases the risk of lethal prostate cancer, particularly when the IGF-IR expression remains at normal level.

IMPACT

PTEN and IGF-IR expression in tumor are promising candidates for independent prognostic factors to predict lethal prostate cancer.

Pleiotropy between genetic markers of obesity and risk of prostate cancer

BACKGROUND

To address inconsistent findings of obesity and prostate cancer risk, we analyzed the association between prostate cancer and genetic markers of obesity and metabolism.

METHODS

Analyses included 176,520 single-nucleotide polymorphisms (SNP) associated with 23 metabolic traits. We examined the association between SNPs and prostate cancer in 871 cases and 906 controls, including 427 high-grade cases with Gleason ≥ 7. Genetic risk scores (GRS) for body mass index (BMI) and waist-to-hip ratio (WHR) were also created by summing alleles associated with increasing BMI or WHR.

RESULTS

Prostate cancer was associated with five loci, including cyclin M2, with P values less than 1 × 10(-4). In addition, the WHR GRS was associated with high-grade prostate cancer versus controls [OR, 1.05; 95% confidence interval (CI), 1.00-1.11; P = 0.048] and high-grade prostate cancer versus low-grade prostate cancer (OR, 1.07; 95% CI, 1.01-1.13; P = 0.03). None of these findings exceeds the threshold for significance after correction for multiple testing.

CONCLUSIONS

Variants in genes known to be associated with metabolism and obesity may be associated with prostate cancer. We show evidence for pleiotropy between WHR GRS and prostate cancer grade. This finding is consistent with the function of several WHR genes and previously described relationships with cancer traits.

IMPACT

Limitations in standard obesity measures suggest alternative characterizations of obesity may be needed to understand the role of metabolic dysregulation in prostate cancer. The underlying genetics of WHR or other Metabochip SNPs, while not statistically significant beyond multiple testing thresholds within our sample size, support the metabolic hypothesis of prostate carcinogenesis and warrant further investigation in independent samples.

Targeting the insulin-like growth factor-1 receptor in human cancer

The insulin-like growth factor (IGF) signaling system plays a crucial role in human cancer and the IGF-1 receptor (IGF-1R) is an attractive drug target against which a variety of novel anti-tumor agents are being developed. Deregulation of the IGF signaling pathway frequently occurs in human cancer and involves the establishment of autocrine loops comprising IGF-1 or IGF-2 and/or IGF-1R over-expression. Epidemiologic studies have documented a link between elevated IGF levels and the development of solid tumors, such as breast, colon, and prostate cancer. Anti-cancer strategies targeting the IGF signaling system involve two main approaches, namely neutralizing antibodies and small molecule inhibitors of the IGF-1R kinase activity. There are numerous reports describing anti-tumor activity of these agents in pre-clinical models of major human cancers. In addition, multiple clinical trials have started to evaluate the safety and efficacy of selected IGF-1R inhibitors, in combination with standard chemotherapeutic regimens or other targeted agents in cancer patients. In this mini review, I will discuss the role of the IGF signaling system in human cancer and the main strategies which have been so far evaluated to target the IGF-1R.

Insulin-like growth factors and insulin-like growth factor-binding proteins and prostate cancer risk: results from the prostate cancer prevention trial

The role of the insulin-like growth factor (IGF) axis and whether IGFs interact with androgen-suppressing agents in relation to prostate carcinogenesis is unclear. This nested case-control study (n = 1,652 cases/1,543 controls) examined whether serum IGF1, IGF2, IGFBP2, IGFBP3, and the IGF1:IGFBP3 ratio were associated with prostate cancer in the Prostate Cancer Prevention Trial (PCPT), a randomized, placebo-controlled trial of finasteride for prostate cancer prevention. Presence or absence of cancer was determined by prostate biopsy. Baseline serum was assayed for IGF-axis analytes using ELISA. Logistic regression estimated ORs and 95% confidence intervals for risk of total, low-grade (Gleason 2-6) and high-grade (Gleason 7-10) cancers. Results were stratified by intervention assignment. In both the placebo and finasteride arms, serum IGF1, IGF2, IGFBP3, and the IGF1:IGFBP3 ratio were not associated with prostate cancer. However, men in the highest versus lowest quartile of serum IGFBP2 had a 48% (P(trend) = 0.02) and 55% (P(trend) = 0.01) increased risk for total and low-grade cancers, respectively. These IGFBP2 associations were attenuated and no longer statistically significant in the finasteride arm. Our results suggest that in general, serum IGF-axis analytes were not associated with prostate cancer risk in the PCPT in which presence or absence of all cancers was biopsy-determined. The exception was the finding that high serum IGFBP2 is a risk factor for low-grade disease, which was attenuated for men on finasteride. Further research is needed to understand better the risk incurred by high IGFBP2 and whether androgen-suppressing agents such as finasteride influence aspects of IGFBP2 physiology relevant to prostate carcinogenesis.

Evidence for the Possible Biological Significance of the igf-1 Gene Alternative Splicing in Prostate Cancer

Insulin-like growth factor-I (IGF-I) has been implicated in the pathogenesis of prostate cancer (PCa), since it plays a key role in cell proliferation, differentiation, and apoptosis. The IGF-I actions are mediated mainly via its binding to the type I IGF receptor (IGF-IR), however IGF-I signaling via insulin receptor (IR) and hybrid IGF-I/IR is also evident. Different IGF-I mRNA splice variants, namely IGF-IEa, IGF-IEb, and IGF-IEc, are expressed in human cells and tissues. These transcripts encode several IGF-I precursor proteins which contain the same bioactive product (mature IGF-I), however, they differ by the length of their signal peptides on the amino-terminal end and the structure of the extension peptides (E-peptides) on the carboxy-terminal end. There is an increasing interest in the possible different role of the IGF-I transcripts and their respective non-(mature)IGF-I products in the regulation of distinct biological activities. Moreover, there is strong evidence of a differential expression profile of the IGF-I splice variants in normal versus PCa tissues and PCa cells, implying that the expression pattern of the various IGF-I transcripts and their respective protein products may possess different functions in cancer biology. Herein, the evidence that the IGF-IEc transcript regulates PCa growth via Ec peptide specific and IGF-IR/IR-independent signaling is discussed.

Global Igfbp1 deletion does not affect prostate cancer development in a c-Myc transgenic mouse model

Circulating insulin-like growth factor binding protein 1 (IGFBP1) levels vary in response to nutritional status, and pre-clinical studies suggest that elevated IGFBP1 may be protective against the development and progression of prostate cancer. We hypothesized that global deletion of Igfbp1 would accelerate the development of prostate cancer in a c-Myc transgenic mouse model. To test our hypothesis, c-Myc transgenic mice (Myc/BP-1 wild-type (WT)) were crossed and interbred with the Igfbp1 knockout mice (Myc/BP-1 KO). The animals were placed on a high-protein diet at weaning, weighed every 2 weeks, and euthanized at 16 weeks of age. Prostate histopathology was assessed and proliferation status was determined by Ki-67 and proliferating cell nuclear antigen analyses. IGF-related serum biomarkers and body composition were measured. No significant difference in the incidence of prostate cancer was observed between the Myc/BP-1 KO and the Myc/BP-1 WT mice (65 and 80% respectively, P=0.48). Proliferation was significantly decreased by 71% in prostate tissue of Myc/BP-1 KO mice compared with Myc/BP-1 WT mice. Myc/BP-1 KO mice exhibited a significant 6.7% increase in body weight relative to the Myc/BP-1 WT mice that was attributed to an increase in fat mass. Fasting insulin levels were higher in the Myc/BP-1 KO mice without any difference between the groups in fasting glucose concentrations. Thus, contrary to our hypothesis, global deletion of Igfbp1 in a c-Myc transgenic mouse model did not accelerate the development of prostate cancer. Global Igfbp1 deletion did result in a significant increase in body weight and body fat mass. Further studies are required to understand the underlying mechanisms for these metabolic effects.

Androgen receptor signaling in prostate cancer development and progression

The androgen receptor (AR) signaling axis plays a critical role in the development, function and homeostasis of the prostate. The classical action of AR is to regulate gene transcriptional processes via AR nuclear translocation, binding to androgen response elements on target genes and recruitment of, or crosstalk with, transcription factors. Prostate cancer initiation and progression is also uniquely dependent on AR. Androgen deprivation therapy remains the standard of care for treatment of advanced prostate cancer. Despite an initial favorable response, almost all patients invariably progress to a more aggressive, castrate-resistant phenotype. Considerable evidence now supports the concept that development of castrate-resistant prostate cancer (CRPC) is causally related to continued transactivation of AR. Understanding the critical events and complexities of AR signaling in the progression to CRPC is essential in developing successful future therapies. This review provides a synopsis of AR structure and signaling in prostate cancer progression, with a special focus on recent findings on the role of AR in CRPC. Clinical implications of these findings and potential directions for future research are also outlined.

Visceral adiposity, insulin resistance and cancer risk

BACKGROUND

There is a well established link between obesity and cancer. Emerging research is characterising this relationship further and delineating the specific role of excess visceral adiposity, as opposed to simple obesity, in promoting tumorigenesis. This review summarises the evidence from an epidemiological and pathophysiological perspective.

METHODS

Relevant medical literature was identified from searches of PubMed and references cited in appropriate articles identified. Selection of articles was based on peer review, journal and relevance.

RESULTS

Numerous epidemiological studies consistently identify increased risk of developing carcinoma in the obese. Adipose tissue, particularly viscerally located fat, is metabolically active and exerts systemic endocrine effects. Putative pathophysiological mechanisms linking obesity and carcinogenesis include the paracrine effects of adipose tissue and systemic alterations associated with obesity. Systemic changes in the obese state include chronic inflammation and alterations in adipokines and sex steroids. Insulin and the insulin-like growth factor axis influence tumorigenesis and also have a complex relationship with adiposity. There is evidence to suggest that insulin and the IGF axis play an important role in mediating obesity associated malignancy.

CONCLUSIONS

There is much evidence to support a role for obesity in cancer progression, however further research is warranted to determine the specific effect of excess visceral adipose tissue on tumorigenesis. Investigation of the potential mechanisms underpinning the association, including the role of insulin and the IGF axis, will improve understanding of the obesity and cancer link and may uncover targets for intervention.

Human prostate cancer xenografts in lit/lit mice exhibit reduced growth and androgen-independent progression

BACKGROUND

The growth hormone/insulin-like growth factor I (GH/IGF-I) axis has been linked to prostate cancer (PCa) risk. Although previous studies indicate that human breast cancers and a murine PCa model develop more slowly in murine hosts homozygous for a missense mutation in the GH-releasing hormone receptor (lit/lit) whose "little" dwarfed phenotype is caused by suppressed GH and IGF-I production, the role of these two hormones remains controversial.

METHODS

To assess how the GH/IGF-I axis influences androgen-responsive, castration-resistant (CR), and androgen-independent (AI) growth of human PCa, we compared xenograft growth of the androgen-responsive human PCa cells, LNCaP, and AI human PCa cells, PC3, in intact and castrate Nod/SCID lit/lit and lit/+ mice, and in vitro growth of these cell lines in lit/lit and lit/+ serum-containing media supplemented with GH or IGF-I.

RESULTS

Tumor growth and PSA accumulation rates were suppressed in LNCaP tumor-bearing lit/lit mice pre- and post-castration. Growth of PC3 xenografts in lit/lit mice was also suppressed. In vitro proliferation of LNCaP and PC3 cells cultured in media containing lit/lit mouse serum was decreased as compared to growth in media containing lit/+ serum. Suppressed growth in lit/lit serum could be restored by the addition of IGF-I, and to a lesser extent, GH. Differences in growth correlated with differences in steady-state AKT and ERK1/2 activation.

CONCLUSIONS

This study demonstrates that circulating GH and IGF-I can promote androgen-responsive growth, CR progression, and AI expansion of PTEN-deficient human PCa cell xenografts and indicates that IGF-I can promote PCa growth in a suppressed GH environment.

Plasma insulin-like growth factor 1 is positively associated with low-grade prostate cancer in the Health Professionals Follow-up Study 1993-2004

The insulin-like growth factor (IGF) axis plays a role in growth and progression of prostate cancer. High circulating IGF-1 levels have been associated with an increased risk of prostate cancer. Results for IGF binding protein 3 (IGFBP-3) are inconclusive. Some studies have indicated that the positive association with IGF-1 is observed only for low-grade prostate cancer (Gleason sum < 7). We previously reported in the Health Professionals Follow-up Study (HPFS) a direct positive association between ELISA-measured plasma IGF-1 and IGFBP-3 and risk of prostate cancer (462 cases diagnosed after providing a blood specimen (between 1993 and 1995), but before February 1998). With additional follow-up through January 31st 2004, and 1,331 case-control pairs in total, we were now able to investigate low-grade (Gleason sum < 7, n = 635) and high-grade (Gleason sum ≥ 7, n = 515) prostate cancer separately. Matched odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic regression. ORs of total prostate cancer comparing top to bottom quartiles were 1.41 (95% CI 1.12-1.78, p-trend = 0.001) for IGF-1 and 1.58 (95% CI 1.24-2.01, p-trend = 0.003) for IGFBP-3. IGF-1 was more strongly associated with low-grade (OR = 1.61 top versus bottom quartile, 95% CI 1.16-2.25, p-trend = 0.01), than with high-grade (OR = 1.29, 95% CI 0.89-1.88, p-trend = 0.12) prostate cancer (p-heterogeneity = 0.08). We hypothesize that these findings reflect that high-grade prostate cancers are more autonomous, and, thus, less sensitive to the action of IGF-1 than low-grade cancers.

Thyroid cancer is the most common cancer associated with acromegaly

The aim of the study was to screen the malignancy in an acromegalic patient group and to determine whether there was any increased risk and the incidence of malignancy and its association with disease characteristics such as duration of disease, latency in diagnosis, and GH and IGF-1 levels. One hundred-five (65 female, 40 male) patients with acromegaly followed and treated at Cerrahpasa Medical School, Endocrinology and Metabolism outpatient clinic between 1983 and 2007 were included in this study. The patients were screened with colonoscopy, mammography, and thyroid and prostate ultrasonography (US). Malignancy was detected in 16 (15%) patients. Thyroid cancer was found in 5 patients (4.7%), breast cancer in 3 (2.8%), colon cancer in 2 (1.9%), lung cancer in 2 (1.9%), cervix cancer in 1 (0.9%), myelodysplastic syndrome (MDS) in 1 (0.9%), cholangiocarcinoma in 1 (0.9%), and multiple endocrine neoplasm (MEN) type 1 in 1 patient (0.9%). Cancer was more common in the male patients (P = 0.046) and high levels of GH increased the risk of cancer development (P = 0.046). In this series, the most commonly detected cancer types were thyroid followed by breast and colon cancers. Although high levels of initial GH seemed to increase the risk of cancer development in acromegalic patients, age, gender, age at the time of diagnosis, duration of disease, and initial IGF-I levels were not associated with cancer development.

Plasma levels of acid-labile subunit, free insulin-like growth factor-I, and prostate cancer risk: a prospective study

BACKGROUND

The acid-labile subunit (ALS) acts in the insulin-like growth (IGF) system by binding circulating IGF-I in a ternary complex with binding protein (IGFBP)-3 to prevent IGF-I from crossing the endothelial barrier. Given the role of the IGF system in prostate cancer, ALS may influence carcinogenesis by modulating IGF-I levels or bioavailability.

METHODS

We undertook a prospective study nested in the Physicians' Health Study to examine ALS, free IGF-I, and prostate cancer. We assayed circulating levels of ALS and IGF components among 545 incident cases and 545 matched controls. We calculated relative risks (RR) and 95% confidence intervals (95% CI) adjusted for life-style factors, total IGF-I, and IGFBP3.

RESULTS

ALS was positively correlated with total IGF-I (r = 0.58), IGFBP3 (r = 0.68), and free IGF-I (r = 0.36). Comparing highest versus lowest quartiles, we found no association between free IGF-I and prostate cancer risk (RR, 0.9; 95% CI, 0.6-1.3). In contrast, ALS was positively associated with risk among men in the 2nd (RR, 1.5; 94% CI, 1.0-2.3), 3rd (RR, 1.6; 94% CI, 1.1-2.5), and 4th quartiles (RR, 1.4; 94% CI, 0.9-2.1) compared with lowest quartile. The association was stronger for advanced stage tumors (RR, 2.0; 94% CI, 0.8-4.6). There was a suggestion of an interaction between ALS and total IGF-I, whereby high circulating IGF-I was associated with an increased risk of advanced prostate cancer among men with low but not higher ALS levels.

DISCUSSION

Plasma ALS is positively associated with prostate cancer risk, and may interact biologically with IGF-I to affect carcinogenesis. These data provide further support for the role of the IGF axis in prostate cancer.

A comprehensive analysis of common IGF1, IGFBP1 and IGFBP3 genetic variation with prospective IGF-I and IGFBP-3 blood levels and prostate cancer risk among Caucasians

The insulin-like growth factor (IGF) pathway has been implicated in prostate development and carcinogenesis. We conducted a comprehensive analysis, utilizing a resequencing and tagging single-nucleotide polymorphism (SNP) approach, between common genetic variation in the IGF1, IGF binding protein (BP) 1, and IGFBP3 genes with IGF-I and IGFBP-3 blood levels, and prostate cancer (PCa) risk, among Caucasians in the NCI Breast and Prostate Cancer Cohort Consortium. We genotyped 14 IGF1 SNPs and 16 IGFBP1/IGFBP3 SNPs to capture common [minor allele frequency (MAF) >or= 5%] variation among Caucasians. For each SNP, we assessed the geometric mean difference in IGF blood levels (N = 5684) across genotypes and the association with PCa risk (6012 PCa cases/6641 controls). We present two-sided statistical tests and correct for multiple comparisons. A non-synonymous IGFBP3 SNP in exon 1, rs2854746 (Gly32Ala), was associated with IGFBP-3 blood levels (P(adj) = 8.8 x 10(-43)) after adjusting for the previously established IGFBP3 promoter polymorphism A-202C (rs2854744); IGFBP-3 blood levels were 6.3% higher for each minor allele. For IGF1 SNP rs4764695, the risk estimates among heterozygotes was 1.01 (99% CI: 0.90-1.14) and 1.20 (99% CI: 1.06-1.37) for variant homozygotes with overall PCa risk. The corrected allelic P-value was 8.7 x 10(-3). IGF-I levels were significantly associated with PCa risk (P(trend) = 0.02) with a 21% increase of PCa risk when compared with the highest quartile to the lowest quartile. We have identified SNPs significantly associated with IGFBP-3 blood levels, but none of these alter PCa risk; however, a novel IGF1 SNP, not associated with IGF-I blood levels, shows preliminary evidence for association with PCa risk among Caucasians.

A phase I study of weekly R1507, a human monoclonal antibody insulin-like growth factor-I receptor antagonist, in patients with advanced solid tumors

PURPOSE

A phase I study was conducted to evaluate the pharmacokinetics, pharmacodynamics, safety, and tolerability of R1507-a fully human IgG1 type monoclonal antibody directed against the human insulin-like growth factor-I receptor.

EXPERIMENTAL DESIGN

Patients with advanced solid tumors were assigned to receive i.v. R1507 weekly (qW), starting with 1 mg/kg. Subsequent cohorts were dosed at 3 and then 9 mg/kg. An additional 12 patients received 9 mg/kg R1507 qW. Patients remained on the study until the development of a dose-limiting toxicity or progressive disease.

RESULTS

In total, 37 patients were treated with R1507 qW. No dose-limiting toxicities were identified and the maximum tolerated dose was not reached. The pharmacokinetics of R1507 were characterized by a slow clearance and limited volume of distribution, with an estimated elimination half-life justifying weekly administration. Serum IGF-I ligand levels increased proportionally to dose during the first 72 hours in all cohorts. R1507 was well tolerated. Two patients diagnosed with Ewing's sarcoma had partial responses of 11.5 and >26 months (ongoing at time of submission); 13 patients had stable disease; and 16 had progressive disease as best response by the Response Evaluation Criteria in Solid Tumors.

CONCLUSION

R1507 is well tolerated and shows antitumor activity in patients with solid neoplasms, in particular Ewing's sarcoma. The recommended dose for the weekly schedule is 9 mg/kg qW.

Metabolic syndrome and cancer

Since its first description by Reavan in 1988, accepted criteria for clinical identification of the components of metabolic syndrome have been promulgated by the National Cholesterol Education Program/Adult Treatment Panel III (NCEP/ATP III) and the World Health Organization (WHO) as well as the International Diabetes Federation (IDF), and the American Association of Clinical Endocrinologists (AACE). Insulin resistance is a common metabolic abnormality underlying type 2 diabetes mellitus and is also an independent risk factor for cardiovascular disease. Although ATP III identified cardiovascular disease (CVD) as the primary clinical outcome of the metabolic syndrome, we now have evidence that metabolic syndrome is associated with type 2 diabetes mellitus, polycystic ovarian disease, nonalcoholic fatty liver disease, and possibly some cancers. This review summarizes evidence in support of the relationship between metabolic syndrome and various cancers and possible underlying mechanisms and therapeutic interventions.

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.

Intake of plant foods and associated nutrients in prostate cancer risk

Plant foods and associated nutrients may impact prostate cancer (PC) risk and survival. Therefore, we compared dietary intake, mainly plant food groups among 382 controls and 478 PC cases (373 incident and 105 prevalent cases). Caucasian controls had significantly higher daily servings of vegetables (3.4 vs. 2.5, P= 0.002) and fruits and/or fruit juices (1.6 vs. 1.3, P = 0.02) compared to African American controls. In Caucasians, incident cases reported lower intake of fiber, vitamin C, vitamin A, alpha -carotene, beta -carotene, cryptoxanthin, folate, genistein, daidzein, and fruits and/or fruit juice than controls and/or prevalent cases. In African Americans, incident cases had lower intake of alpha -carotene compared to controls and prevalent cases. Reduced PC risk was associated with the highest tertile of cryptoxanthin (OR = 0.51; 95% CI = 0.35-0.75), fiber (OR = 0.56; 95% CI = 0.35-0.89), vitamin C (OR = 0.60; 95% CI = 0.41-0.88), and fruits and/or fruit juices (OR = 0.46; 95% CI = 0.31-0.68), with significant linear trends. Increased risk of PC was associated with the highest tertile of protein (OR = 1.99; 95% CI = 1.05-3.79) and daily servings of grains (OR = 1.99; 95% CI = 1.23-3.22) with significant linear trends. In summary, we demonstrate racial/ethnic differences in dietary intake of plant foods. The significantly higher consumption of protective dietary constituents among prevalent cases compared to incident cases suggests that PC survivors may be amenable to dietary change.

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.

NKX3.1 activates expression of insulin-like growth factor binding protein-3 to mediate insulin-like growth factor-I signaling and cell proliferation

NKX3.1 is a homeobox gene that codes for a haploinsufficient prostate cancer tumor suppressor. NKX3.1 protein levels are down-regulated in the majority of primary prostate cancer tissues. NKX3.1 expression in PC-3 cells increased insulin-like growth factor binding protein-3 (IGFBP-3) mRNA expression 10-fold as determined by expression microarray analysis. In both stably and transiently transfected PC-3 cells and in LNCaP cells, NKX3.1 expression increased IGFBP-3 mRNA and protein expression. In prostates of Nkx3.1 gene-targeted mice Igfbp-3 mRNA levels correlated with Nkx3.1 copy number. NKX3.1 expression in PC-3 cells attenuated the ability of insulin-like growth factor-I (IGF-I) to induce phosphorylation of type I IGF receptor (IGF-IR), insulin receptor substrate 1, phosphatidylinositol 3-kinase, and AKT. The effect of NKX3.1 on IGF-I signaling was not seen when cells were exposed to long-R3-IGF-I, an IGF-I variant peptide that does not bind to IGFBP-3. Additionally, small interfering RNA-induced knockdown of IGFBP-3 expression partially reversed the attenuation of IGF-IR signaling by NKX3.1 and abrogated NKX3.1 suppression of PC-3 cell proliferation. Thus, there is a close relationship in vitro and in vivo between NKX3.1 and IGFBP-3. The growth-suppressive effects of NKX3.1 in prostate cells are mediated, in part, by activation of IGFBP-3 expression.

Emerging Biomarkers for the Diagnosis and Prognosis of Prostate Cancer

Background: Early detection of prostate cancer (CaP), the most prevalent cancer and the second-leading cause of death in men, has proved difficult, and current detection methods are inadequate. Prostate-specific antigen (PSA) testing is a significant advance for early diagnosis of patients with CaP.

Content: PSA is produced almost exclusively in the prostate, and abnormalities of this organ are frequently associated with increased serum concentrations. Because of PSA’s lack of specificity for CaP, however, many patients undergo unnecessary biopsies or treatments for benign or latent tumors, respectively. Thus, a more specific method of CaP detection is required to augment or replace screening with PSA. The focus recently has been on creating cost-effective assays for circulating protein biomarkers in the blood, but because of the heterogeneity of CaP, it has become clear that this effort will be a formidable challenge. Each marker will require proper validation to ensure clinical utility. Although much work has been done on variations of the PSA test (i.e., velocity, density, free vs bound, proisoforms) with limited usefulness, there are many emerging markers at various stages of development that show some promise for CaP diagnosis. These markers include kallikrein-related peptidase 2 (KLK2), early prostate cancer antigen (EPCA), PCA3, hepsin, prostate stem cell antigen, and α-methylacyl-CoA racemase (AMACR). We review biomarkers under investigation for the early diagnosis and management of prostate cancer.

Summary: It is hoped that the use of panels of markers can improve CaP diagnosis and prognosis and help predict the therapeutic response in CaP patients.

Insulin and insulin-like growth factor signalling in neoplasia

Insulin and insulin-like growth factors (IGFs) are well known as key regulators of energy metabolism and growth. There is now considerable evidence that these hormones and the signal transduction networks they regulate have important roles in neoplasia. Epidermiological, clinical and laboratory research methods are being used to investigate novel cancer prevention and treatment strategies related to insulin and IGF signalling. Pharmacological strategies under study include the use of novel receptor-specific antibodies, receptor kinase inhibitors and AMP-activated protein kinase activators such as metformin. There is evidence that insulin and IGF signalling may also be relevant to dietary and lifestyle factors that influence cancer risk and cancer prognosis. Recent results are encouraging and have justified the expansion of many translational research programmes.

Insulin-like growth factors, their binding proteins, and prostate cancer risk: analysis of individual patient data from 12 prospective studies

BACKGROUND

Some, but not all, published results have shown an association between circulating blood levels of some insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) and the subsequent risk for prostate cancer.

PURPOSE

To assess the association between levels of IGFs and IGFBPs and the subsequent risk for prostate cancer.

DATA SOURCES

Studies identified in PubMed, Web of Science, and CancerLit.

STUDY SELECTION

The principal investigators of all studies that published data on circulating concentrations of sex steroids, IGFs, or IGFBPs and prostate cancer risk using prospectively collected blood samples were invited to collaborate.

DATA EXTRACTION

Investigators provided individual participant data on circulating concentrations of IGF-I, IGF-II, IGFBP-II, and IGFBP-III and participant characteristics to a central data set in Oxford, United Kingdom.

DATA SYNTHESIS

The study included data on 3700 men with prostate cancer and 5200 control participants. On average, case patients were 61.5 years of age at blood collection and received a diagnosis of prostate cancer 5 years after blood collection. The greater the serum IGF-I concentration, the greater the subsequent risk for prostate cancer (odds ratio [OR] in the highest vs. lowest quintile, 1.38 [95% CI, 1.19 to 1.60]; P < 0.001 for trend). Neither IGF-II nor IGFBP-II concentrations were associated with prostate cancer risk, but statistical power was limited. Insulin-like growth factor I and IGFBP-III were correlated (r = 0.58), and although IGFBP-III concentration seemed to be associated with prostate cancer risk, this was secondary to its association with IGF-I levels. Insulin-like growth factor I concentrations seemed to be more positively associated with low-grade than high-grade disease; otherwise, the association between IGFs and IGFBPs and prostate cancer risk had no statistically significant heterogeneity related to stage or grade of disease, time between blood collection and diagnosis, age and year of diagnosis, prostate-specific antigen level at recruitment, body mass index, smoking, or alcohol intake.

LIMITATIONS

Insulin-like growth factor concentrations were measured in only 1 sample for each participant, and the laboratory methods to measure IGFs differed in each study. Not all patients had disease stage or grade information, and the diagnosis of prostate cancer may differ among the studies.

CONCLUSION

High circulating IGF-I concentrations are associated with a moderately increased risk for prostate cancer.

Glycemic status and risk of prostate cancer

BACKGROUND

To examine the risk of prostate cancer and glucose tolerance in a large, racially diverse cohort.

METHODS

We conducted a cohort study of 47,209 male members of Kaiser Permanente Northern California who had completed at least one Multiphasic Health Checkup (MHC) between 1964 and 1973. The MHC provided information on diabetes, serum glucose 1 h after a 75-g oral glucose challenge test, demographics, and other health conditions. Cox proportional hazards were used to estimate relative risks (RR) while adjusting for confounders.

RESULTS

During a median follow-up of 18.4 years, a total of 2,833 men developed prostate cancer. At baseline, 4.6% (n = 2,159) of the cohort had diabetes and 33% had serum glucose of >or=200 mg/dL. After adjusting for age, race, birth year, and body mass index, RR (95% confidence interval) of prostate cancer associated with 1-h serum glucose >or=200 mg/dL and diabetes were 0.90 (0.81-1.01) and 0.71 (0.62-0.79), respectively, when compared with those with serum glucose <140 mg/dL. During the first 10 years of follow-up, risk was increased among those with serum glucose >or=200 mg/dL or diabetes [RR (95% confidence interval), 1.42 (0.95-2.13) and 1.56 (0.91-2.67), respectively]. In contrast, inverse associations between serum glucose >or=200 mg/dL and diabetes and prostate cancer risk were observed [0.87 (0.77-0.97) and 0.68 (0.52-0.88), respectively] when follow-up began 10 years after MHC.

CONCLUSION

Our findings are consistent with the hypothesis that prostate cancer risk differs by time since diabetes diagnosis or occurrence of metabolic aberrations associated with impaired glucose tolerance.