Levels of insulin-like growth factor I (IGF-I) and IGF binding proteins 2 and 3 in serial postoperative serum samples and risk of prostate cancer recurrence

Emerging Role of IGF-1 in Prostate Cancer: A Promising Biomarker and Therapeutic Target

Prostate cancer (PCa) is a highly heterogeneous disease driven by gene alterations and microenvironmental influences. Not only enhanced serum IGF-1 but also the activation of IGF-1R and its downstream signaling components has been increasingly recognized to have a vital driving role in the development of PCa. A better understanding of IGF-1/IGF-1R activity and regulation has therefore emerged as an important subject of PCa research. IGF-1/IGF-1R signaling affects diverse biological processes in cancer cells, including promoting survival and renewal, inducing migration and spread, and promoting resistance to radiation and castration. Consequently, inhibitory reagents targeting IGF-1/IGF-1R have been developed to limit cancer development. Multiple agents targeting IGF-1/IGF-1R signaling have shown effects against tumor growth in tumor xenograft models, but further verification of their effectiveness in PCa patients in clinical trials is still needed. Combining androgen deprivation therapy or cytotoxic chemotherapeutics with IGF-1R antagonists based on reliable predictive biomarkers and developing and applying novel agents may provide more desirable outcomes. This review will summarize the contribution of IGF-1 signaling to the development of PCa and highlight the relevance of this signaling axis in potential strategies for cancer therapy.

Are plasma Insulin-Like Growth Factor I (IGF-I) and Igf-Binding Protein 3 (Igfbp-3) Useful Markers of Prostate Cancer?

Increased concentrations of insulin-like growth factor I (IGF-I) and decreased insulin-like growth factor binding protein 3 (IGFBP-3) in serum have been proposed as markers of prostate cancer (CaP). The evidence for this, however, is contradictory. We assayed serum for IGF-I, IGFBP-3 and prostate-specific antigen (PSA) in patients with CaP and benign prostatic hyperplasia (BPH) and in healthy controls (HC). The mean ± SD concentration of IGF-I in CaP (98.3 ± 39.3 ng/mL; n=15) was lower than in BPH (119 ± 31.1 ng/mL; n=24) and HC (119 ± 36.1 ng/mL; n=46), but the differences between the three groups were not statistically significant (p>0.05). The mean IGFBP-3 concentrations in CaP (2691 ± 1105 ng/mL; n=16; p=0.029) and BPH (2618 ± 816 ng/mL; n= 26; p=0.006) patients were significantly lower than that of the HC (3119 ± 618 ng/mL; n=59), but the difference between the two groups of patients was not significant (p>0.05). PSA concentrations in CaP (median=80.8 ng/mL; n=25) were significantly higher than those in BPH (median=8.6 ng/mL; n=39) (p<0.001). Ninety-six percent of CaP and 72% of BPH patients had PSA concentrations >4.0 ng/mL; the proportions of patients with concentrations exceeding 20 ng/mL were 76% and 10%, respectively. We conclude that IGF-I and IGFBP-3 are inferior to PSA for CaP detection.

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.

Antibody-Array-Based Proteomic Screening of Serum Markers in Systemic Lupus Erythematosus: A Discovery Study

A discovery study was carried out where serum samples from 22 systemic lupus erythematosus (SLE) patients and matched healthy controls were hybridized to antibody-coated glass slide arrays that interrogated the level of 274 human proteins. On the basis of these screens, 48 proteins were selected for ELISA-based validation in an independent cohort of 28 SLE patients. Whereas AXL, ferritin, and sTNFRII were significantly elevated in patients with active lupus nephritis (LN) relative to SLE patients who were quiescent, other molecules such as OPN, sTNFRI, sTNFRII, IGFBP2, SIGLEC5, FAS, and MMP10 exhibited the capacity to distinguish SLE from healthy controls with ROC AUC exceeding 90%, all with p < 0.001 significance. These serum markers were next tested in a cohort of 45 LN patients, where serum was obtained at the time of renal biopsy. In these patients, sTNFRII exhibited the strongest correlation with eGFR (r = -0.50, p = 0.0014) and serum creatinine (r = 0.57, p = 0.0001), although AXL, FAS, and IGFBP2 also correlated with these clinical measures of renal function. When concurrent renal biopsies from these patients were examined, serum FAS, IGFBP2, and TNFRII showed significant positive correlations with renal pathology activity index, while sTNFRII displayed the highest correlation with concurrently scored renal pathology chronicity index (r = 0.57, p = 0.001). Finally, in a longitudinal cohort of seven SLE patients examined at ∼3 month intervals, AXL, ICAM-1, IGFBP2, SIGLEC5, sTNFRII, and VCAM-1 demonstrated the ability to track with concurrent disease flare, with significant subject to subject variation. In summary, serum proteins have the capacity to identify patients with active nephritis, flares, and renal pathology activity or chronicity changes, although larger longitudinal cohort studies are warranted.

Biomarkers for evaluation of prostate cancer prognosis

Prostate cancer, with a lifetime prevalence of one in six men, is the second cause of malignancy-related death and the most prevalent cancer in men in many countries. Nowadays, prostate cancer diagnosis is often based on the use of biomarkers, especially prostate-specific antigen (PSA) which can result in enhanced detection at earlier stage and decreasing in the number of metastatic patients. However, because of the low specificity of PSA, unnecessary biopsies and mistaken diagnoses frequently occur. Prostate cancer has various features so prognosis following diagnosis is greatly variable. There is a requirement for new prognostic biomarkers, particularly to differentiate between inactive and aggressive forms of disease, to improve clinical management of prostate cancer. Research continues into finding additional markers that may allow this goal to be attained. We here selected a group of candidate biomarkers including PSA, PSA velocity, percentage free PSA, TGFβ1, AMACR, chromogranin A, IL-6, IGFBPs, PSCA, biomarkers related to cell cycle regulation, apoptosis, PTEN, androgen receptor, cellular adhesion and angiogenesis, and also prognostic biomarkers with Genomic tests for discussion. This provides an outline of biomarkers that are presently of prognostic interest in prostate cancer investigation.

IGF-Binding Protein 2 - Oncogene or Tumor Suppressor?

The role of insulin-like growth factor binding protein 2 (IGFBP2) in cancer is unclear. In general, IGFBP2 is considered to be oncogenic and its expression is often observed to be elevated in cancer. However, there are a number of conflicting reports in vitro and in vivo where IGFBP2 acts in a tumor suppressor manner. In this mini-review, we discuss the factors influencing the variation in IGFBP2 expression in cancer and our interpretation of these findings.

A cross-sectional analysis of the association between diet and insulin-like growth factor (IGF)-I, IGF-II, IGF-binding protein (IGFBP)-2, and IGFBP-3 in men in the United Kingdom

BACKGROUND

There is evidence of associations between insulin-like growth factor I (IGF-I), IGF-II, insulin-like binding protein-2 (IGFBP-2), IGFBP-3, and prostate cancer risk. This study examines the association between dietary factors associated with prostate cancer and serum levels of these peptides.

METHODS

A cross-sectional analysis of self-reported 12-month dietary intake with serum IGF and IGFBP levels was performed using data from 1,798 subjects screened negative for prostate cancer as part of a UK multicenter trial comparing treatments for this condition. Multivariable linear regression models tested associations of diet with IGFs and IGFBPs.

RESULTS

For a one standard deviation (SD) increase in dairy product and dairy protein intake, IGF-I increased by 5.28 ng/mL (95 % confidence interval: 2.64, 7.92 ng/mL) and 6.02 ng/mL (3.34, 8.71 ng/mL), respectively. A 25 % increase in calcium and selenium intake was associated with an increase in IGF-I of 5.92 ng/mL (3.77, 8.07 ng/mL) and 2.61 ng/mL (1.10, 4.13 ng/mL), respectively. A one SD increase in animal protein was associated with a decrease in IGFBP-2 of 6.20 % (-8.91, -3.41 %), and there was some evidence of an inverse association with dairy protein and calcium. There was no evidence of any dietary associations with IGFBP-3 or IGF-II.

CONCLUSIONS

Diet is associated with IGF-I and IGFBP-2 levels in men in the UK, and these peptides warrant further investigation as part of randomized trials of dietary interventions to reduce the risk or progression of prostate cancer. There is no evidence that IGF-II or IGFBP-3 are mediators of dietary associations with prostate cancer.

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.

Induction of IGF-1R expression by EGR-1 facilitates the growth of prostate cancer cells

The transcription factor Early Growth Response-1 (EGR-1) is overexpressed in human prostate tumors and contributes to prostate cancer progression through an unknown mechanism. Here we report that EGR-1 transcriptionally regulates the expression of insulin-like growth factor-1 receptor (IGF-1R), which is highly expressed in primary prostate cancer. We find that ectopic expression of EGR-1 causes increase in IGF-1R expression, while knockdown of EGR-1 leads to dramatically decrease in IGF-1R expression. Results from chromatin immunoprecipitation (ChIP) and reporter assay show that the EGR-1 directly binds to the human IGF-1R gene and triggers the target gene expression. EGR-1 activates Erk and Akt pathway through regulation of IGF-1R, and thus promote prostate cancer cell growth. Taken together, these results suggest that EGR-1 may stimulate prostate cancer cell growth through up-regulation of IGF-1R and indicate that down-regulation of EGR-1 could be an effective therapeutic approach against prostate cancer.

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-binding protein-2 is a target for the immunomodulation of breast cancer

Breast cancer is immunogenic and well suited to treatment via immunomodulation. The disease is often treated to remission and time to relapse is generally measured in years in many cases. Immune-based therapeutics, such as cancer vaccines, may be able to affect the clinical progression of micrometastatic disease. Immune targets must be identified that have the potential to inhibit tumor growth. Insulin-like growth factor-binding protein-2 (IGFBP-2) has direct effects on breast cancer proliferation via stimulation of critical signaling pathways. We questioned whether IGFBP-2 was an immune target in breast cancer. IGFBP-2-specific IgG antibody immunity was preferentially detected in breast cancer patients compared with controls (P = 0.0008). To evaluate for the presence of T-cell immunity, we identified potential pan-HLA-DR binding epitopes derived from IGFBP-2 and tested the peptides for immunogenicity. The majority of epitopes elicited peptide-specific T cells in both patients and controls and had high sequence homology to bacterial pathogens. IGFBP-2 peptide-specific T cells could respond to naturally processed and presented IGFBP-2 protein, indicating that these peptides were native epitopes of IGFBP-2. Finally, both immunization with IGFBP-2 peptides as well as adoptive transfer of IGFBP-2-competent T cells mediated an antitumor effect in a transgenic mouse model of breast cancer. This is the first report of IGFBP-2 as a human tumor antigen that may be a functional therapeutic target in breast cancer.

Expression of components of the IGF axis in childhood acute myelogenous leukemia

BACKGROUND

Insulin-like growth factor (IGF) system as regulator for cellular proliferation is of particular interest in search for new prognostic approaches in cancer treatment.

PROCEDURE

We analyzed the mRNA expression profile of IGF-I, -II, and IGFBP-2, -3 in 50 children with previously untreated AML (mean age 10.8 +/- 4.8 years; patients in CCR n = 20, patients with relapse during later course of disease n = 15). MNC samples from peripheral blood as well as bone marrow of healthy donors were used as controls.

RESULTS

IGFBP-2 expression was significantly higher in AML cells than in healthy cells of peripheral MNC (P < 0.001) and of bone marrow cells (P < 0.01). Conversely, AML cells showed significantly lower IGFBP-3 and IGF-I gene expression compared to controls (P = 0.02; P < 0.001). Patients with relapse (median +/- range: 0.0929 +/- 0.049) during later course of disease demonstrated higher IGFBP-2 expression compared to patients in CCR (0.0121 +/- 0.047; P = 0.06) at time of diagnosis. A multivariate analysis identified the IGFBP-2 mRNA expression as an independent factor for the prediction of relapse. Furthermore, the probability of relapse-free survival (RFS) in patients with IGFBP-2 mRNA level >0.1000 was 28%; whereas, the probability of RFS in patients with IGFBP-2 mRNA level <0.1000 was 62% (P = 0.04, log-rank test). No prognostic influence could be found for the other investigated genes.

CONCLUSIONS

Results identified different expressions of IGF components between normal and AML cells. Patients with IGFBP-2 mRNA levels up to 0.1000 (relative to KG1 cell line) more likely developed a relapse. Identification of these patients at diagnosis may allow more individualized treatment.

Relationship of Dietary Protein and Soy Isoflavones to Serum IGF-1 and IGF Binding Proteins in the Prostate Cancer Lifestyle Trial

High levels of insulin-like growth factor 1 (IGF-1) are associated with increased risk of prostate cancer, whereas increased levels of some of its binding proteins (IGFBPs) seem to be protective. High intakes of dietary protein, especially animal and soy protein, appear to increase IGF-1. However, soy isoflavones have demonstrated anti-proliferative and apoptotic effects both in vitro and in vivo. We evaluated dietary intakes of total protein and soy isoflavones in relation to the IGF axis in prostate cancer patients making comprehensive lifestyle changes including a very low-fat vegan diet supplemented with soy protein (58 g/day). After one year, intervention group patients reported significantly higher intakes of dietary protein and soy isoflavones compared to usual-care controls (P < 0.001). IGF-1 increased significantly in both groups, whereas IGFBP-1 rose in the experimental group only (P < 0.01). Increases in vegetable protein over one year were associated with increases in IGFBP-1 among intervention group patients (P < 0.05). These results suggest that dietary protein and soy isoflavones, in the context of comprehensive lifestyle changes, may not significantly alter IGF-1. However, given the recent literature indicating that high intake of protein rich in essential amino acids (animal or soy protein) may increase IGF-1, it may be prudent for men with early stage prostate cancer not to exceed dietary protein recommendations.

Targeted therapies for prostate cancer

The development of targeted therapies for prostate cancer has exploited various elements of prostate biology. The androgen-dependence of prostate cancer continues to be the focus for the development of new drugs and the analysis of details of the intermolecular interactions of the androgen receptor. Importantly, new applications of androgen ablation therapy have proven to have the greatest effect on cause-specific and overall survival during the last decade. Prostate epithelial cells express a number of tissue-specific proteins that have been the target either for antibody-directed therapies, in the case of prostate-specific membrane antigen, or target-activated therapies in the case of prostate-specific antigen, a serine protease. Prostate-specific proteins have also been targeted by the development of vaccines that have entered clinical trials. Humanized monoclonal antibodies and small molecules designed to inhibit oncogenic signalling pathways have been subjected to clinical trials in prostate cancer with limited success. The application of pathway inhibitors to prostate cancer therapy has been limited because no common dominant oncogenic mutation affecting signal kinase activation in prostate cancer has yet been identified. The interaction of signal kinase inhibitors with androgen ablation and with cytotoxic chemotherapy remains to be explored.

Elevated serum insulin-like growth factor binding protein-2 is associated with a high relapse risk after hematopoietic stem cell transplantation in childhood AML

Insulin-like growth factor binding protein (IGFBP)-2 has mitogenic effects in normal and neoplastic cells. The purpose of this study is to examine the diagnostic and prognostic significance of elevated IGFBP-2 levels in children with AML after hematopoietic stem cell transplantation (HSCT) at relapse and continuous complete remission (CCR). In 27 children with AML (mean age 13.6+/-5.3 years; patients in remission n=15 with relapse n=12) serum parameters of IGFBP-2, IGFBP-3, IGF-I and IGF-II were analyzed up to 18 months after HSCT by RIA. AML-patients with evidence of relapse demonstrated a continuous increase of IGFBP-2 levels during the follow-up. At day 100 after HSCT, IGFBP-2 concentrations were significantly higher in patients with relapse than in children without relapse (7.4+/-4.0 standard deviation score (SDS) vs 3.9+/-1.7 SDS; P=0.01). Serum IGFBP-2 was identified as an independent factor for the prediction of relapse. Furthermore, the probability of relapse-free survival (RFS) in patients with IGFBP-2 >4.5 SDS at day 100 after HSCT was 31% compared to patients with IGFBP-2 <4.5 SDS was 72% (P=0.004). Patients with IGFBP-2 concentration up to 4.5 SDS more likely developed a relapse and had a poorer outcome. Identification of these patients allows a more individualized and aggressive adjuvant treatment and follow-up.

Prognostic factors in prostate cancer

Prognostic factors in organ confined prostate cancer will reflect survival after surgical radical prostatectomy. Gleason score, tumour volume, surgical margins and Ki-67 index have the most significant prognosticators. Also the origins from the transitional zone, p53 status in cancer tissue, stage, and aneuploidy have shown prognostic significance. Progression-associated features include Gleason score, stage, and capsular invasion, but PSA is also highly significant. Progression can also be predicted with biological markers (E-cadherin, microvessel density, and aneuploidy) with high level of significance. Other prognostic features of clinical or PSA-associated progression include age, IGF-1, p27, and Ki-67. In patients who were treated with radiotherapy the survival was potentially predictable with age, race and p53, but available research on other markers is limited. The most significant published survival-associated prognosticators of prostate cancer with extension outside prostate are microvessel density and total blood PSA. However, survival can potentially be predicted by other markers like androgen receptor, and Ki-67-positive cell fraction. In advanced prostate cancer nuclear morphometry and Gleason score are the most highly significant progression-associated prognosticators. In conclusion, Gleason score, capsular invasion, blood PSA, stage, and aneuploidy are the best markers of progression in organ confined disease. Other biological markers are less important. In advanced disease Gleason score and nuclear morphometry can be used as predictors of progression. Compound prognostic factors based on combinations of single prognosticators, or on gene expression profiles (tested by DNA arrays) are promising, but clinically relevant data is still lacking.

Insulin-like growth factor binding protein 2: an androgen-dependent predictor of prostate cancer survival

BACKGROUND

Evidence suggests that the insulin-like growth factor (IGF) family is important in prostate cancer. We evaluate the ability of IGF markers to predict biochemical recurrence-free survival (bRFS) following radical prostatectomy (RRP).

METHODS

Preoperative sera from 141 patients undergoing RRP were analyzed for IGF-I, IGFBP-1, IGFBP-2 and IGFBP-3. A multivariate Cox model was created to assess the ability of these markers to predict bRFS. Preoperative covariables included: biopsy Gleason score, clinical TNM stage, serum PSA and neoadjuvant hormonotherapy. Kaplan-Meier curves were stratifying by IGF cutpoints (determined by ROC analysis) and hormonotherapy status.

RESULTS

Average follow-up was 6.92 years, median PSA was 6.9 ng/ml and 85.1% of patients had cT2NxM0 disease. 49 patients experienced a PSA failure. Average levels of IGF-I, IGFBP-1, IGFBP-2 and IGFBP-3 were 156.5 ng/ml, 48.1 ng/ml, 396.8 ng/ml and 3303.7 ng/ml, respectively. IGFBP-2 was an independent predictor of PSA failure. Patients treated with neoadjuvant ADT (n=71) and whom had high IGFBP-2 levels experienced a 5-year bRFS that was better than those with low IGFBP-2 levels (77.7% vs. 53.3%). Patients without neoadjuvant ADT whom had high IGFBP-2 levels had a 5-year bRFS that was worse than those with low IGFBP-2 levels (64.5% vs. 82.7%).

CONCLUSIONS

Preoperative IGFBP-2 predicts post-radical prostatectomy bRFS and is independent of stage, Gleason score and PSA. Increased IGFBP-2 is associated with better survival in patients with neoadjuvant hormonotherapy but worse survival in those without, suggesting a dramatic switch in function of this protein dependent on the presence or absence of androgens.

Circulating free insulin-like growth factor (IGF)-I, total IGF-I, and IGF binding protein-3 levels do not predict the future risk to develop prostate cancer: results of a case-control study involving 201 patients within a population-based screening with a 4-year interval

Recent studies have reported that serum IGF-I levels in the highest quartile of the normal range and IGF binding protein-3 (IGFBP-3) in the lowest quartile of the normal range are associated with an increased risk of future prostate cancer and/or presence of prostate cancer. It has also been suggested that the measurement of circulating total IGF-I concentrations might be a useful tool for the early detection of prostate cancer in men with moderately increased prostate-specific antigen (PSA) levels. To determine whether circulating free IGF-I, total IGF-I, and IGFBP-3 levels can predict future prostate cancer risk, we prospectively studied prostate cancer characteristics in a cohort of men during two rounds (mean interval, 4 yr) of a population-based screening study for prostate cancer. Two hundred one prostate cancer cases were detected at the second-round screening (aged 55-70 yr), and all these subjects were enrolled in the case group for the present study. Prostate cancer had been confirmed by biopsy in all cases. These 201 subjects were matched with the 201 nonprostate cancer cases by age, serum PSA range at the first-round screening (PSA < 2 ng/ml, n = 67; PSA = 2-3 ng/ml, n = 67; and PSA = 3-4 ng/ml, n = 67), and residence area. At baseline, total IGF-I, free IGF-I, and IGFBP-3 levels and prostate volume of cases with prostate cancer were not different from those of healthy controls. PSA velocity was significantly different between cases and controls (P < 0.001).Stepwise forward logistic regression analysis showed that only PSA levels at baseline and PSA at round 2 after 4 yr are good predictors of prostate cancer, whereas total IGF-I, free IGF-I, and IGFBP-3 did not predict the development of prostate cancer. Only one of the 201 subjects with prostate cancer had metastases. Within the subjects with prostate cancer, there were no differences of IGF-I parameters with different tumor node metastasis categories and/or Gleason scores. Our study suggests that the measurement of serum IGF-I and/or IGFBP-3 concentrations in addition to PSA does not improve the identification of men at high risk to develop early stages of prostate cancer. In addition, our results indicate that the endocrine IGF-I system is not directly involved in the growth of the early stages of prostate cancer.

Serum insulin-like growth factor (IGF)-1 and IGF-binding protein-3 do not correlate with Gleason score or quantity of prostate cancer in biopsy samples

OBJECTIVE

To examine the relationship of serum insulin-like growth factor (IGF)-1 and IGF binding protein-3 (IGFBP-3) with histological cancer characteristics in men undergoing transrectal ultrasonography (TRUS)-guided biopsy.

PATIENTS AND METHODS

Patients (652), with either an elevated serum prostate-specific antigen level or an abnormal digital rectal examination, were initially evaluated by TRUS and sextant prostatic needle biopsy. Blood was drawn before biopsy, serum extracted and stored frozen until IGF-1 and IGFBP-3 were measured. In all, 241 patients had prostate cancer (37%) and were included in this study. The number of positive biopsies, the volume of tumour in each positive biopsy and the Gleason score were recorded.

RESULTS

Of the 241 patients, 37 had five or six positive biopsies (from six), 128 had two to four and 76 had one. Serum IGF-1 did not correlate with the number of positive biopsies, with means of 176.7, 178.3 and 164.4 ng/mL, respectively (P = 0.3), while the mean IGFBP-3 was 2695, 2795 and 2572 ng/mL, respectively (P = 0.09). The additive percentiles of tumour volume in positive biopsies were assessed for each patient but serum IGF-1 and IGFBP-3 did not correlate (P = 0.7 and 0.9, respectively). In all, 92 patients had a Gleason score of < 7, 80 a score of 7 and 69 a score of > 7; the mean (sd) IGF-1 levels for the three groups were 181 (39), 174.6 (35) and 176 (26) ng/mL, and the mean IGFBP-3 2798 (240), 2735 (284) and 2647 (221) ng/mL, respectively, none of the differences being statistically significant.

CONCLUSIONS

Serum IGF-1 and IGFBP-3 do not correlate with quantity of cancer or Gleason score in biopsy samples from patients with prostate cancer.

Changes of serum growth factors (IGF-I,-II and IGFBP-2,-3) prior to and after stem cell transplantation in children with acute leukemia

SUMMARY

Insulin-like growth factors (IGFs) and IGF-binding proteins (IGFBPs) may play an important role in tumor proliferation. This study aimed to investigate the IGF system in children with acute leukemia prior to and after hematological stem cell transplantation (HSCT). In 51 patients (AML n=27; ALL n=24; mean age 11.2+/-4.8 years), serum parameters (IGF-I,-II, IGFBP-2,-3) were investigated up to 18 months after HSCT by RIA. Patients with AML showed a significant increase of IGFBP-2 up to 100 days after HSCT (mean +/-s.d. prior to HSCT: 3.2+/-3.6 SDS vs 100 days after HSCT: 5.3 degrees +/-3.4 SDS, P=0.005). Furthermore, IGF-I and IGFBP-3 were significantly decreased (IGF-I: -0.3+/-1.5 vs -0.7 +/-1.2 SDS, P=0.001; IGFBP-3: -0.3+/-1.1 vs -1.0+/-1.1 SDS, P=0.02). Children with AML showed significantly higher IGFBP-2 (P=0.04) and significantly lower IGF-I (P=0.03) and IGFBP-3 (P=0.05) levels than children with ALL at day 100 after HSCT. We conclude that children with acute leukemia show important changes in the IGF system after HSCT. In particular, IGFBP-2 was significantly elevated at day 100 after HSCT. Increased IGFBP-2 and decreased IGF-I and IGFBP-3 may be associated with the increased proliferation rate of transplanted bone marrow.

The role of the IGF system in cancer: from basic to clinical studies and clinical applications

Insulin-like growth factors (IGFs) are important mediators of growth, development, and survival, are synthesized by almost any tissue in the body, and their action is modulated by a complex network of molecules, including binding proteins, proteases and receptors, which all comprise the IGF system. Evidence from in vitro and animal studies suggests that overexpression of IGFs by cancer cells and/or the nearby stroma as well as the type IGF-I receptor by the cancer cells may play a significant role in establishing a transformed phenotype in an increasing number of malignancies. More specifically, IGFs may promote cell cycle progression and inhibition of apoptosis either by directly associating with other growth factors or indirectly by interacting with other molecular systems which have an established role in carcinogenesis and cancer promotion, such as the steroid hormones and integrins. In addition, a growing number of epidemiologic studies suggest that increased serum levels of IGFs and/or altered levels of their binding proteins are associated with increased risk for developing several malignancies. These data indicate that IGF dysregulation should now be considered as an important independent factor for cancer risk, and a potential target for novel antineoplastic therapies and/or preventative strategies in high-risk groups.