Tumor suppressor BRCA1 is expressed in prostate cancer and controls insulin-like growth factor I receptor (IGF-IR) gene transcription in an androgen receptor-dependent manner

Insulin-like growth factor family and prostate cancer: new insights and emerging opportunities

Prostate cancer is the second most commonly diagnosed cancer in men. The mammalian insulin-like growth factor (IGF) family is made up of three ligands (IGF-I, IGF-II, and insulin), three receptors (IGF-I receptor (IGF-1R), insulin receptor (IR), and IGF-II receptor (IGF-2R)), and six IGF-binding proteins (IGFBPs). IGF-I and IGF-II were identified as potent mitogens and were previously associated with an increased risk of cancer development including prostate cancer. Several reports showed controversy about the expression of the IGF family and their connection to prostate cancer risk due to the high degree of heterogeneity among prostate tumors, sampling bias, and evaluation techniques. Despite that, it is clear that several IGF family members play a role in prostate cancer development, metastasis, and androgen-independent progression. In this review, we aim to expand our understanding of prostate tumorigenesis and regulation through the IGF system. Further understanding of the role of IGF signaling in PCa shows promise and needs to be considered in the context of a comprehensive treatment strategy.

Androgen receptor signaling-mitochondrial DNA-oxidative phosphorylation: A critical triangle in early prostate cancer

Mitochondria are more than just the cellular powerhouse. They also play key roles in vital functions such as apoptosis, metabolism regulation, and other intracellular interactions. The mitochondrial DNA (mtDNA) encodes for 12 subunits of the oxidative phosphorylation (OXPHOS) system. Depletion of mtDNA in androgen-dependent prostate cancer (PCa) cell lines renders them androgen-independent and more aggressive. Paradoxically, pharmaceutical inhibition of OXPHOS is lethal for subsets of PCa cells, whereas others become dependent on androgen receptor (AR) signaling for survival. Given that the AR-mitochondria interaction is critical for early PCa, it is crucial to understand the details of this interaction. Technical hurdles have made mitochondria traditionally difficult to study, with many techniques used for isolation masking the properties of given individual mitochondria. Although the isolation of mitochondria enables us to study OXPHOS, we miss the context in which mitochondria interact with the rest of the cell. Both AR signaling and mtDNA affect apoptosis, metabolism regulation, cellular calcium storage and homeostasis, intracellular calcium signaling, and redox homeostasis. In this review, we will attempt to understand how the crosstalk between AR-mtDNA-OXPHOS is responsible for "life or death" decisions inside the cells. Our aim is to point toward potential vulnerabilities that can lead to the discovery of novel therapeutic targets.

Hallmarks of cancer: The insulin-like growth factors perspective

The identification of a series of attributes or hallmarks that are shared by virtually all cancer cells constitutes a true milestone in cancer research. The conceptualization of a catalogue of common genetic, molecular, biochemical and cellular events under a unifying Hallmarks of Cancer idea had a major impact in oncology. Furthermore, the fact that different types of cancer, ranging from pediatric tumors and leukemias to adult epithelial cancers, share a large number of fundamental traits reflects the universal nature of the biological events involved in oncogenesis. The dissection of a complex disease like cancer into a finite directory of hallmarks is of major basic and translational relevance. The role of insulin-like growth factor-1 (IGF1) as a progression/survival factor required for normal cell cycle transition has been firmly established. Similarly well characterized are the biochemical and cellular activities of IGF1 and IGF2 in the chain of events leading from a phenotypically normal cell to a diseased one harboring neoplastic traits, including growth factor independence, loss of cell-cell contact inhibition, chromosomal abnormalities, accumulation of mutations, activation of oncogenes, etc. The purpose of the present review is to provide an in-depth evaluation of the biology of IGF1 at the light of paradigms that emerge from analysis of cancer hallmarks. Given the fact that the IGF1 axis emerged in recent years as a promising therapeutic target, we believe that a careful exploration of this signaling system might be of critical importance on our ability to design and optimize cancer therapies.

BRCA Mutations in Ovarian and Prostate Cancer: Bench to Bedside

Simple Summary

DNA damage is one of the hallmarks of cancer. Epithelial ovarian cancer (EOC) —especially the high-grade serous subtype—harbors a defect in at least one DNA damage response (DDR) pathway. Defective DDR results from a variety of lesions affecting homologous recombination (HR) and nonhomologous end joining (NHEJ) for double strand breaks, base excision repair (BER), and nucleotide excision repair (NER) for single strand breaks and mismatch repair (MMR). Apart from the EOC, mutations in the DDR genes, such as BRCA1 and BRCA2, are common in prostate cancer as well. Among them, BRCA2 lesions are found in 12% of metastatic castration-resistant prostate cancers, but very rarely in primary prostate cancer. Better understanding of the DDR pathways is essential in order to optimize the therapeutic choices, and has led to the design of biomarker-driven clinical trials. Poly(ADP-ribose) polymerase (PARP) inhibitors are now a standard therapy for EOC patients, and more recently have been approved for the metastatic castration-resistant prostate cancer with alterations in DDR genes. They are particularly effective in tumours with HR deficiency.

Abstract

DNA damage repair (DDR) defects are common in different cancer types, and these alterations can be exploited therapeutically. Epithelial ovarian cancer (EOC) is among the tumours with the highest percentage of hereditary cases. BRCA1 and BRCA2 predisposing pathogenic variants (PVs) were the first to be associated with EOC, whereas additional genes comprising the homologous recombination (HR) pathway have been discovered with DNA sequencing technologies. The incidence of DDR alterations among patients with metastatic prostate cancer is much higher compared to those with localized disease. Genetic testing is playing an increasingly important role in the treatment of patients with ovarian and prostate cancer. The development of poly (ADP-ribose) polymerase (PARP) inhibitors offers a therapeutic strategy for patients with EOC. One of the mechanisms of PARP inhibitors exploits the concept of synthetic lethality. Tumours with BRCA1 or BRCA2 mutations are highly sensitive to PARP inhibitors. Moreover, the synthetic lethal interaction may be exploited beyond germline BRCA mutations in the context of HR deficiency, and this is an area of ongoing research. PARP inhibitors are in advanced stages of development as a treatment for metastatic castration-resistant prostate cancer. However, there is a major concern regarding the need to identify reliable biomarkers predictive of treatment response. In this review, we explore the mechanisms of DDR, the potential for genomic analysis of ovarian and prostate cancer, and therapeutics of PARP inhibitors, along with predictive biomarkers.

BRCA1: An Endocrine and Metabolic Regulator

The breast and ovarian cancer susceptibility gene (BRCA1) is a tumor suppressor whose mutation has been associated with the development of breast, ovarian and, probably, other malignancies at young ages. The BRCA1 gene product participates in multiple biological pathways including the DNA damage response, transcriptional control, cell growth and apoptosis. Inactivating germline mutations of the BRCA1 gene can be detected in a substantial portion of families with inherited breast and/or ovarian cancer. While the genomic and cancer-related actions of BRCA1 have been extensively investigated, not much information exists regarding the cellular and circulating factors involved in regulation of BRCA1 expression and action. The present review article dissects the emerging role of BRCA1 as an important regulator of various endocrine and metabolic axes. Experimental and clinical evidence links BRCA1 with a number of peptide and steroid hormones. Furthermore, comprehensive analyses identified complex interactions between the insulin/insulin-like growth factor-1 (IGF1) signaling axis and BRCA1. The correlation between metabolic disorders, including diabetes and the metabolic syndrome, and BRCA1 mutations, are discussed in this article.

BRCA Mutations in Prostate Cancer: Assessment, Implications and Treatment Considerations

Prostate cancer ranks fifth in cancer-related mortality in men worldwide. DNA damage is implicated in cancer and DNA damage response (DDR) pathways are in place against this to maintain genomic stability. Impaired DDR pathways play a role in prostate carcinogenesis and germline or somatic mutations in DDR genes have been found in both primary and metastatic prostate cancer. Among these, BRCA mutations have been found to be especially clinically relevant with a role for germline or somatic testing. Prostate cancer with DDR defects may be sensitive to poly(ADP-ribose) polymerase (PARP) inhibitors which target proteins in a process called PARylation. Initially they were used to target BRCA-mutated tumor cells in a process of synthetic lethality. However, recent studies have found potential for PARP inhibitors in a variety of other genetic settings. In this review, we explore the mechanisms of DNA repair, potential for genomic analysis of prostate cancer and therapeutics of PARP inhibitors along with their safety profile.

Tumor protein expression of the DNA repair gene BRCA1 and lethal prostate cancer

DNA repair genes are commonly altered in metastatic prostate cancer, but BRCA1 mutations are rare. Preliminary studies suggest that higher tumor expression of the BRCA1 protein may be associated with worse prognosis. We undertook a prospective study among men with prostate cancer in the Health Professionals Follow-up Study and evaluated BRCA1 via immunohistochemical staining on tissue microarrays. BRCA1 was expressed in 60 of 589 tumors. Prevalence of BRCA1 positivity was 43% in the 14 men with metastases at diagnosis compared with 9% in non-metastatic tumors [difference, 33 percentage points; 95% confidence interval (CI), 7-59]. BRCA1-positive tumors had 2.16-fold higher Ki-67 proliferative indices (95% CI, 1.18-3.95), higher tumor aneuploidy as predicted from whole-transcriptome profiling, and higher Gleason scores. Among the 575 patients with non-metastatic disease at diagnosis, we evaluated the association between BRCA1 expression and development of lethal disease (metastasis or cancer-specific death, 69 events) during long-term follow-up (median, 18.3 years). A potential weak association of BRCA1 positivity with lethal disease (hazard ratio, 1.61; 95% CI, 0.82-3.15) was attenuated when adjusting for age, Gleason score and clinical stage (hazard ratio, 1.11; 95% CI, 0.54-2.29). In summary, BRCA1 protein expression is a feature of more proliferative and more aneuploid prostate tumors and is more common in metastatic disease. While not well suited as a prognostic biomarker in primary prostate cancer, BRCA1 protein expression may be most relevant in advanced disease.

The role of insulin-like growth factors in the development of prostate cancer

INTRODUCTION

Preclinical, clinical, and population studies have provided robust evidence for an important role for the insulin-like growth factor (IGF) system in the development of prostate cancer.

AREAS COVERED

An overview of the IGF system is provided. The evidence implicating the IGF system in the development of prostate cancer is summarized. The compelling evidence culminated in a number of clinical trials of agents targeting the system; the reasons for the failure of these trials are discussed.

EXPERT OPINION

Clinical trials of agents targeting the IGF system in prostate cancer were terminated due to limited objective clinical responses and are unlikely to be resumed unless a convincing predictive biomarker is identified that would enable the selection of likely responders. The aging population and increased screening will lead to greater diagnosis of prostate cancer. Although the vast majority will be indolent disease, the epidemics of obesity and diabetes will increase the proportion that progress to clinical disease. The increased population of worried men will result in more trials aimed to reduce the risk of disease progression; actual clinical endpoints will be challenging and the IGFs remain the best intermediate biomarkers to indicate a response that could alter the course of disease.

The decline of FANCM immunohistochemical expression in prostate cancer stroma correlates with the grade group

Prostate adenocarcinoma (PCa) stromal markers have recently gained attention as complementary diagnostic tools. The DNA reparation complex protein FANCM has been shown to express in the normal prostate stroma and FANCM gene alterations to be associated with PCa susceptibility; this has led to the hypothesis that an insufficient level of FANCM expression may provide additional information for the evaluation of PCa. The study cohort comprised 60 radical prostatectomy specimens. The controls involved 11 autopsies (CTRL) and non-cancerous tissue (NCT) areas from the prostatectomy specimen. The samples were stained with the FANCM antibody. The quantification of the stromal staining index (SSI) was made using ImageJ and QuPath. Overall, 655 regions of interest (ROI) were analyzed. FANCM expression appeared equally intense and stroma specific in both CTRL and NCT, indicating the absence of underlying baseline alterations. Within the age span of the cohort 47-89 years, no significant effect of the age of the patients on the FANCM expression was seen. FANCM demonstrated Gleason grade (G) dependent decline in PCa, being statistically significant in controls versus G1 and G2 versus G3. In other adjacent International Society of Urological Pathology (ISUP) groups, it remained insignificant, still being meaningful between high and low-grade cancers.

BRCA1 and VDR gene polymorphisms are associated with prostate cancer risk in Mexican men

Prostate cancer (PC) is a polygenic disease with broad differences across ethnicities. BRCA1/2 and VDR have exhibited a featured genetic contribution to PC development in European populations. Nonetheless, its contribution in Latino populations specifically among Mexican men, where 70% of PC cases are detected in advanced stages, is still unknown. The contribution of seven polymorphisms in BRCA1/2 and VDR genes to PC susceptibility was evaluated in 370 incident PC cases and 759 age-matched (±5 years) controls belonging to the Mexican population. Based on Gleason score at diagnosis, PC cases were classified as well-differentiated PC (Gleason <7) and moderate or poorly differentiated PC (Gleason ≥7). Age at diagnosis was used to divided PC cases in earlier (<60 years) and late-onset PC (≥60 years). Prostate and breast cancer family histories were obtained through interview. Our results provided evidences about the contribution of BRCA1-rs1799966 (OR_{CC genotype}  = 2.30; 95% confidence interval [CI] = 1.36-3.91) to the moderate or poorly differentiated PC risk, independently of the family history of prostate, breast or ovary cancer. Further, VDR-rs2238135-G allele was associated with early-onset PC (OR_{G allele}  = 2.05; 95% CI = 1.06-3.95), and marginally with moderate or poorly differentiated PC risk. The present study revealed the crucial role of BRCA1 in PC aggressiveness risk, outstanding the gender imbalance regarding the breast cancer risk in women.

Investigational IGF1R inhibitors in early stage clinical trials for cancer therapy

Introduction: The insulin-like growth factors (IGFs) are a family of secreted peptide hormones with important roles in different cellular and organism functions. The biological activities of the IGFs are mediated by the IGF1 receptor (IGF1R), a cell surface, tyrosine kinase-containing heterotetramer that is linked to numerous cytoplasmic signaling cascades. The IGF1R displays potent antiapoptotic, pro-survival capacities and plays a key role in malignant transformation. Research has identified the IGF1R as a candidate therapeutic target in cancer.Areas covered: We offer a synopsis of ongoing efforts to target the IGF axis for therapeutic purposes. Our review includes a digest of early experimental work that led to the identification of IGF1R as a candidate therapeutic target in oncology.Expert opinion: Targeting of the IGF axis has yielded disappointing results in phase III trials, but it is important to learn from this to improve future trials in a rational manner. The potential of anti-IGF1R antibodies and small molecular weight inhibitors, alone or in combination with chemotherapy or other biological agents, should be investigated further in randomized studies. Moreover, the implementation of predictive biomarkers for patient selection will improve the outcome of future trials. Emerging personalized medicine could have a major impact on IGF1R targeting.

CYR61 triggers osteosarcoma metastatic spreading via an IGF1Rβ-dependent EMT-like process

BACKGROUND

Osteosarcoma is the most prevalent primary bone malignancy in children and young adults. These tumors are highly metastatic, leading to poor outcome. We previously demonstrated that Cysteine-rich protein 61 (CYR61/CCN1) expression level is correlated to osteosarcoma aggressiveness in preclinical model and in patient tumor samples. The aim of the present study was to investigate the CYR61-induced intracellular mechanisms leading to the acquisition of an invasive phenotype by osteosarcoma cells.

METHODS

Modified murine and human osteosarcoma cell lines were evaluated for cell adhesion, aggregation (spheroid), motility (wound healing assay), phenotypic markers expression (RT-qPCR, western blot). Cell-derived xenograft FFPE samples and patients samples (TMA) were assessed by IHC.

RESULTS

CYR61 levels controlled the expression of markers related to an Epithelial-mesenchymal transition (EMT)-like process, allowing tumor cells to migrate acquiring a competent morphology, and to be able to invade the surrounding stroma. This phenotypic shift indeed correlated with tumor grade and aggressiveness in patient samples and with the metastatic dissemination potential in cell-derived xenograft models. Unlike EGFR or PDGFR, IGF1Rβ levels correlated with CYR61 and N-cadherin levels, and with the aggressiveness of osteosarcoma and overall survival. The expression levels of IGF1Rβ/IGF1 axis were controlled by CYR61, and anti-IGF1 neutralizing antibody prevented the CYR61-induced phenotypic shift, aggregation, and motility abilities.

CONCLUSIONS

Taken together, our study provides new evidence that CYR61 acts as a key inducing factor in the metastatic progression of osteosarcoma by playing a critical role in primary tumor dissemination, with a process associated with IGF1/IGFR stimulation. This suggests that CYR61 may represent a potential pivotal target for therapeutic management of metastases spreading in osteosarcoma, in correlation with IGF1/IGFR pathway.

Systemic Effects of Segmental Vibration in an Animal Model of Hand-Arm Vibration Syndrome

OBJECTIVE

Epidemiology suggests that occupational exposure to hand-transmitted (segmental) vibration has local and systemic effects. This study used an animal model of segmental vibration to characterize the systemic effects of vibration.

METHODS

Male Sprague Dawley rats were exposed to tail vibration for 10 days. Genes indicative of inflammation, oxidative stress, and cell cycle, along were measured in the heart, kidney, prostate, and liver.

RESULTS

Vibration increased oxidative stress and pro-inflammatory gene expression, and decreased anti-oxidant enzymes in heart tissue. In the prostate and liver, vibration resulted in changes in the expression of pro-inflammatory factors and genes involved in cell cycle regulation.

CONCLUSIONS

These changes are consistent with epidemiological studies suggesting that segmental vibration has systemic effects. These effects may be mediated by changes in autonomic nervous system function, and/or inflammation and oxidative stress.

Elucidating the novel BRCA1 function as a non-genomic metabolic restraint in ER-positive breast cancer cell lines

Within populations carrying the same genetic predisposition, the penetrance of BRCA1 mutations has increased over time. Although linked to changes in lifestyle factors associated with energy metabolism, these observations cannot be explained by the established role of BRCA1 in DNA repair alone. We manipulated BRCA1 expression using tetracycline in the UBR60-bcl2 cell line (which has an inducible, tetracycline-regulated BRCA1 expression) and siRNA in oestrogen receptor(ER)-positive MCF7 and T47D breast cancer cells. Cellular responses to BRCA1 silencing and IGF-I actions were investigated using western blotting, 3-H Thymidine incorporation assay, cell fractionation and co-immunoprecipitation. We demonstrated that the loss of BRCA1 resulted in downregulation of a phosphorylated and inactive form of acetyl CoA Carboxylase-α (ACCA), with a concomitant increase in fatty acid synthase (FASN) abundance. BRCA1 was predominantly cytoplasmic in ER-positive breast cancer cells, compatible with the observation that BRCA1 physically associates with phosphorylated ACCA, which is a cytoplasmic protein. We also found that IGF-I induced de-phosphorylation of ACCA by reducing the interaction between BRCA1 and phosphorylated ACCA. BRCA1 deficiency enhanced the non-genomic effects of IGF-I, as well as the proliferative responses of cells to IGF-I. We characterized a novel, non-genomic role for BRCA1 in restraining metabolic activity and IGF-I anabolic actions.

Health effects associated with occupational exposure to hand-arm or whole body vibration

Workers in a number of different occupational sectors are exposed to workplace vibration on a daily basis. This exposure may arise through the use of powered-hand tools or hand-transmitted vibration (HTV). Workers might also be exposed to whole body vibration (WBV) by driving delivery vehicles, earth moving equipment, or through use of tools that generate vibration at low dominant frequencies and high amplitudes, such as jackhammers. Occupational exposure to vibration has been associated with an increased risk of musculoskeletal pain in the back, neck, hands, shoulders, and hips. Occupational exposure may also contribute to the development of peripheral and cardiovascular disorders and gastrointestinal problems. In addition, there are more recent data suggesting that occupational exposure to vibration may enhance the risk of developing certain cancers. The aim of this review is to provide an assessment of the occupations where exposure to vibration is most prevalent, and a description of the adverse health effects associated with occupational exposure to vibration. This review will examine (1) various experimental methods used to measure and describe the characteristics of vibration generated by various tools and vehicles, (2) the etiology of vibration-induced disorders, and (3) how these data were employed to assess and improve intervention strategies and equipment that reduces the transmission of vibration to the body. Finally, there is a discussion of the research gaps that need to be investigated to further reduction in the incidence of vibration-induced illnesses and injuries.

Investigating BRCA Mutations: A Breakthrough in Precision Medicine of Castration-Resistant Prostate Cancer

Despite the development of novel effective therapeutic strategies, metastatic castration-resistant prostate cancer (mCRPC) remains a disease with a lethal course and a high biological and molecular heterogeneity. To date, germline mutations in the BRCA gene represent one of the main risk factors for developing prostate cancer, with a strong association with aggressive phenotype and poor clinical outcomes. A better understanding of the genomic landscape of prostate cancer has strengthened the idea that "synthetic lethality" of this disease might be useful in cancer-drug discovery, focusing on agents such as platinum compounds and poly (adenosine diphosphate [ADP]-ribose) polymerase inhibitors (PARPi). In this review, we summarize the main data available on BRCA mutations and discuss the clinical implications of these genomic aberrations in the management of prostate cancer, stressing the need to identify prognostic and predictive biomarkers and to deeply understand the mechanisms of treatment resistance, in order to maximize personalized medicine protocols and therefore clinical benefit.

Identification of BRCA1 As a Potential Biomarker for Insulin-Like Growth Factor-1 Receptor Targeted Therapy in Breast Cancer

The insulin-like growth factor-1 receptor (IGF1R) emerged in recent years as a promising therapeutic target in oncology. Identification of potential biomarkers capable of predicting response to IGF1R-targeted therapy is of cardinal importance. Tumor suppressor BRCA1 has important roles in multiple pathways, including gene transcription, DNA damage repair, and control of apoptosis. Early studies have identified the IGF1R gene as a downstream target for inhibitory regulation by wild-type, but not mutant, BRCA1. The aim of the present study was to evaluate the hypothesis that the mutational status of BRCA1 may influence the ability of IGF1R-directed therapies to efficiently inhibit the IGF1R axis. Using breast cancer-derived cell lines expressing a wild-type or a mutant BRCA1, we demonstrate that the capacity of MK-0646, a monoclonal antibody antagonist to the human IGF1R, to inhibit insulin-like growth factor-1-stimulated IGF1R and downstream mediators' phosphorylation was impaired in mutant BRCA1-expressing cell lines. In addition, the antibody was able to reduce proliferation of wild-type BRCA1-expressing cells but had a reduced inhibitory effect in mutant BRCA1-expressing cells. In summary, our data indicate that the mutational status of BRCA1 must be taken into account when selecting patients for IGF1R targeting protocols.

Formal modeling and analysis of ER-α associated Biological Regulatory Network in breast cancer

BACKGROUND

Breast cancer (BC) is one of the leading cause of death among females worldwide. The increasing incidence of BC is due to various genetic and environmental changes which lead to the disruption of cellular signaling network(s). It is a complex disease in which several interlinking signaling cascades play a crucial role in establishing a complex regulatory network. The logical modeling approach of René Thomas has been applied to analyze the behavior of estrogen receptor-alpha (ER-α) associated Biological Regulatory Network (BRN) for a small part of complex events that leads to BC metastasis.

METHODS

A discrete model was constructed using the kinetic logic formalism and its set of logical parameters were obtained using the model checking technique implemented in the SMBioNet software which is consistent with biological observations. The discrete model was further enriched with continuous dynamics by converting it into an equivalent Petri Net (PN) to analyze the logical parameters of the involved entities.

RESULTS

In-silico based discrete and continuous modeling of ER-α associated signaling network involved in BC provides information about behaviors and gene-gene interaction in detail. The dynamics of discrete model revealed, imperative behaviors represented as cyclic paths and trajectories leading to pathogenic states such as metastasis. Results suggest that the increased expressions of receptors ER-α, IGF-1R and EGFR slow down the activity of tumor suppressor genes (TSGs) such as BRCA1, p53 and Mdm2 which can lead to metastasis. Therefore, IGF-1R and EGFR are considered as important inhibitory targets to control the metastasis in BC.

CONCLUSION

The in-silico approaches allow us to increase our understanding of the functional properties of living organisms. It opens new avenues of investigations of multiple inhibitory targets (ER-α, IGF-1R and EGFR) for wet lab experiments as well as provided valuable insights in the treatment of cancers such as BC.

Transcriptional Pathways Altered in Response to Vibration in a Model of Hand-Arm Vibration Syndrome

OBJECTIVE

The aim of this study was to use an established model of vibration-induced injury to assess frequency-dependent changes in transcript expression in skin, artery, and nerve tissues.

METHODS

Transcript expression in tissues from control and vibration-exposed rats (4 h/day for 10 days at 62.5, 125, or 250 Hz; 49 m/s, rms) was measured. Transcripts affected by vibration were used in bioinformatics analyses to identify molecular- and disease-related pathways associated with exposure to vibration.

RESULTS

Analyses revealed that cancer-related pathways showed frequency-dependent changes in activation or inhibition. Most notably, the breast-related cancer-1 pathway was affected. Other pathways associated with breast cancer type 1 susceptibility protein related signaling, or associated with cancer and cell cycle/cell survivability were also affected.

CONCLUSION

Occupational exposure to vibration may result in DNA damage and alterations in cell signaling pathways that have significant effects on cellular division.

Purification of Bone Marrow Clonal Cells from Patients with Myelodysplastic Syndrome via IGF-IR

Malignant clonal cells purification can greatly benefit basic and clinical studies in myelodysplastic syndrome (MDS). In this study, we investigated the potential of using type 1 insulin-like growth factor receptor (IGF-IR) as a marker for purification of malignant bone marrow clonal cells from patients with MDS. The average percentage of IGF-IR expression in CD34⁺ bone marrow cells among 15 normal controls was 4.5%, 70% of which also express the erythroid lineage marker CD235a. This indicates that IGF-IR mainly express in erythropoiesis. The expression of IGF-IR in CD34⁺ cells of 55 MDS patients was significantly higher than that of cells from the normal controls (54.0 vs. 4.5%). Based on the pattern of IGF-IR expression in MDS patients and normal controls, sorting of IGF-IR-positive and removal of CD235a-positive erythroid lineage cells with combination of FISH detection were performed on MDS samples with chromosomal abnormalities. The percentage of malignant clonal cells significantly increased after sorting. The enrichment effect was more significant in clonal cells with a previous percentage lower than 50%. This enrichment effect was present in samples from patients with +8, 5q-/-5, 20q-/-20 or 7q-/-7 chromosomal abnormalities. These data suggest that IGF-IR can be used as a marker for MDS bone marrow clonal cells and using flow cytometry for positive IGF-IR sorting may effectively purify MDS clonal cells.

The insulin-like growth factor (IGF) axis as an anticancer target in prostate cancer

Prostate cancer (PCa) is the most common cancer and the second leading cause of cancer death in males. In recent years, several new targeting agents have been introduced for the treatment of advanced stages of the disease. However, development of resistance limits the efficacy of new drugs and there is a further need to develop additional novel treatment approaches. One of the most investigated targets in cancer research is the insulin-like growth factor (IGF) axis, whose receptors are overexpressed in several cancer entities including PCa. In preclinical studies in PCa, targeting of the IGF axis receptors showed promising anti-tumor effects. Currently available data on clinical studies do not meet the expectations for this new treatment approach. In this review we provide a summary of preclinical and clinical studies on the IGF axis in PCa including treatment with monoclonal antibodies and tyrosine kinase inhibitors. Moreover, we summarize preliminary results from ongoing studies and discuss limitations and side effects of the substances used. We also address the role of the IGF axis in the biomarkers setting including IGF-binding proteins and genetic variants.

A novel method for identifying disease associated protein complexes based on functional similarity protein complex networks

Background

Protein complexes formed by non-covalent interaction among proteins play important roles in cellular functions. Computational and purification methods have been used to identify many protein complexes and their cellular functions. However, their roles in terms of causing disease have not been well discovered yet. There exist only a few studies for the identification of disease-associated protein complexes. However, they mostly utilize complicated heterogeneous networks which are constructed based on an out-of-date database of phenotype similarity network collected from literature. In addition, they only apply for diseases for which tissue-specific data exist.

Methods

In this study, we propose a method to identify novel disease-protein complex associations. First, we introduce a framework to construct functional similarity protein complex networks where two protein complexes are functionally connected by either shared protein elements, shared annotating GO terms or based on protein interactions between elements in each protein complex. Second, we propose a simple but effective neighborhood-based algorithm, which yields a local similarity measure, to rank disease candidate protein complexes.

Results

Comparing the predictive performance of our proposed algorithm with that of two state-of-the-art network propagation algorithms including one we used in our previous study, we found that it performed statistically significantly better than that of these two algorithms for all the constructed functional similarity protein complex networks. In addition, it ran about 32 times faster than these two algorithms. Moreover, our proposed method always achieved high performance in terms of AUC values irrespective of the ways to construct the functional similarity protein complex networks and the used algorithms. The performance of our method was also higher than that reported in some existing methods which were based on complicated heterogeneous networks. Finally, we also tested our method with prostate cancer and selected the top 100 highly ranked candidate protein complexes. Interestingly, 69 of them were evidenced since at least one of their protein elements are known to be associated with prostate cancer.

Conclusions

Our proposed method, including the framework to construct functional similarity protein complex networks and the neighborhood-based algorithm on these networks, could be used for identification of novel disease-protein complex associations.

Electronic supplementary material

The online version of this article (doi:10.1186/s13015-015-0044-6) contains supplementary material, which is available to authorized users.

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.

Phosphoprotein phosphatase 1-interacting proteins as therapeutic targets in prostate cancer

Prostate cancer is a major public health concern worldwide, being one of the most prevalent cancers in men. Great improvements have been made both in terms of early diagnosis and therapeutics. However, there is still an urgent need for reliable biomarkers that could overcome the lack of cancer-specificity of prostate-specific antigen, as well as alternative therapeutic targets for advanced metastatic cases. Reversible phosphorylation of proteins is a post-translational modification critical to the regulation of numerous cellular processes. Phosphoprotein phosphatase 1 (PPP1) is a major serine/threonine phosphatase, whose specificity is determined by its interacting proteins. These interactors can be PPP1 substrates, regulators, or even both. Deregulation of this protein-protein interaction network alters cell dynamics and underlies the development of several cancer hallmarks. Therefore, the identification of PPP1 interactome in specific cellular context is of crucial importance. The knowledge on PPP1 complexes in prostate cancer remains scarce, with only 4 holoenzymes characterized in human prostate cancer models. However, an increasing number of PPP1 interactors have been identified as expressed in human prostate tissue, including the tumor suppressors TP53 and RB1. Efforts should be made in order to identify the role of such proteins in prostate carcinogenesis, since only 26 have yet well-recognized roles. Here, we revise literature and human protein databases to provide an in-depth knowledge on the biological significance of PPP1 complexes in human prostate carcinogenesis and their potential use as therapeutic targets for the development of new therapies for prostate cancer.

The convergence of DNA damage checkpoint pathways and androgen receptor signaling in prostate cancer

It is increasingly clear that castration-resistant prostate cancer (PCa) is dependent on the androgen receptor (AR). This has led to the use of anti-androgen therapies that reduce endogenous steroid hormone production as well as the use of AR antagonists. However, the AR does not act in isolation and integrates with a milieu of cell-signaling proteins to affect cell biology. It is well established that cancer is a genetic disease resulting from the accumulation of mutations and chromosomal translocations that enables cancer cells to survive, proliferate, and disseminate. To maintain genomic integrity, there exists conserved checkpoint signaling pathways to facilitate cell cycle delay, DNA repair, and/or apoptosis in response to DNA damage. The AR interacts with, affects, and is affected by these DNA damage-response proteins. This review will focus on the connections between checkpoint signaling and the AR in PCa. We will describe what is known about how components of checkpoint signaling regulate AR activity and what questions still face the field.

Transcriptional and epigenetic control of IGF1R gene expression: implications in metabolism and cancer

IGF1R plays an important role in protection from apoptosis, regulation of cell growth, differentiation and oncogenic transformation. IGF1R aberrations lead to intrauterine and postnatal growth failure, microcephaly, mental retardation and deafness. High levels of IGF1R are detected in a diversity of human tumors. IGF1R gene transcription is controlled by complex interactions involving DNA-binding and non DNA-binding transcription factors. This review highlights selected examples of a series of tumor suppressors, including the breast cancer gene-1 (BRCA1), p53, the Wilm's tumor protein-1 (WT1) and the von Hippel-Lindau gene (VHL), whose mechanisms of action involve regulation of IGF1R gene expression. IGF1R gene transcription is also dependent on the presence of stimulatory nuclear proteins, including zinc-finger protein Sp1, EWS-WT1, E2F1, Krüppel-like factor-6 (KLF6), high-mobility group A1 (HMGA1), and others. Loss-of-function of tumor suppressor genes, usually caused by mutations, may result in non-functional proteins unable to control IGF1R promoter activity. Impaired regulation of the IGF1R gene is linked to defective cell division, chromosomal instability and increased incidence of cancer.

IGF-1 and BRCA1 signalling pathways in familial cancer

The insulin-like growth factor (IGF) system has a direct effect on cellular proliferation and survival, and interacts with genetic and environmental factors implicated in causing cancer. Experimental, clinical, and epidemiological evidence show that the IGF signalling pathways are important mediators in the biochemical and molecular chain of events that lead from a phenotypically normal cell to one harbouring neoplastic traits. BRCA1 and BRCA2 have an important role in the development of hereditary and sporadic breast and ovarian cancer. Recent evidence suggests that risk of cancer conferred by BRCA mutations can be modified by genetic and environmental factors, including ambient concentrations of IGF-1 and polymorphisms in IGF system components. This Review addresses interactions between the IGF and BRCA1 signalling pathways, and emphasises the convergence of IGF-1-mediated cell survival, proliferative pathways, and BRCA1-mediated tumour protective pathways. Understanding the complex interactions between these signalling pathways might improve our understanding of basic molecular oncology processes and help to identify new molecular targets, predictive biomarkers, and approaches for optimising cancer therapies.

BRCA1 is expressed in uterine serous carcinoma (USC) and controls insulin-like growth factor I receptor (IGF-IR) gene expression in USC cell lines

OBJECTIVE

The insulin-like growth factor I receptor (IGF-IR) and BRCA1 affect cell growth and apoptosis. Little information is available about BRCA1 activity on the IGF signaling pathway. This study evaluated the effect of BRCA1 on IGF-IR expression.

METHODS

BRCA1 and IGF-IR immunohistochemistry on archival tissues (35 uterine serous carcinomas [USCs] and 17 metastases) were performed. USPC1 and USPC2 cell lines were transiently cotransfected with an IGF-IR promoter construct driving a luciferase reporter gene and a BRCA1 expression plasmid. Endogenous IGF-IR levels were evaluated by Western immunoblotting.

RESULTS

We found high BRCA1 and IGF-IR protein expression in primary and metastatic USC tumors. All samples were immunostained for BRCA1-71% strongly stained; and 33/35 (94%) were stained positive for IGF-IR-2 (6%) strongly stained. No difference in BRCA1 and IGF-IR staining intensity was noted between BRCA1/2 mutation carriers and noncarriers. Metastatic tumors stained more intensely for BRCA1 than did the primary tumor site (P = 0.041) and with borderline significance for IGF-IR (P = 0.069). BRCA1 and IGF-IR staining did not correlate to survival. BRCA1 expression led to 35% and 54% reduction in IGF-IR promoter activity in the USPC1 and USCP2 cell lines, respectively. Western immunoblotting showed a decline in phosphorylated IGF-IR and phosphorylated AKT in both transiently and stably transfected cells.

CONCLUSIONS

BRCA1 and IGF-IR are highly expressed in USC tumors. BRCA1 suppresses IGF-IR gene expression and activity. These findings suggest a possible biological link between the BRCA1 and the IGF-I signaling pathways in USC. The clinical implications of this association need to be explored.

BRCA1 negatively regulates IGF-1 expression through an estrogen-responsive element-like site

The insulin-like growth factor-1 receptor (IGF-1R) signaling pathway is critical for both normal mammary gland development and malignant transformation. It has been reported that the IGF-1 stimulates breast cancer cell proliferation and is upregulated in tumors with BRCA1/2 mutations. We report here that IGF-1 is negatively regulated by BRCA1 at the transcriptional level in human breast cancer cells. BRCA1 knockdown (BRCA1-KD) induces the expression of IGF-1 mRNA in MCF7 cells in an estrogen receptor α (ERα)-dependent manner. We found that both BRCA1 and ERα bind to the endogenous IGF-1 promoter region containing an estrogen-responsive element-like (EREL) site. BRCA1-KD does not significantly affect ERα binding on the IGF-1 promoter. Reporter analysis demonstrates that BRCA1 could regulate IGF-1 transcripts via this EREL site. In addition, enzyme-linked immunosorbent assay revealed that de-repression of IGF-1 transcription by BRCA1-KD increases the level of extracellular IGF-1 protein, and secreted IGF-1 seems to increase the phospho-IGF-1Rβ and activate its downstream signaling pathway. Blocking the IGF-1/IGF-1R/phosphoinositide 3-kinase (PI3K)/AKT pathway either by a neutralizing antibody or by small-molecule inhibitors preferentially reduces the proliferation of BRCA1-KD cells. Furthermore, the IGF-1-EREL-Luc reporter assay demonstrates that various inhibitors, which can inhibit the IGF-1R pathway, can suppress this reporter activity. These findings suggest that BRCA1 defectiveness keeps turning on IGF-1/PI3K/AKT signaling, which significantly contributes to increase cell survival and proliferation.

The role of BRCA1 and BRCA2 in prostate cancer

One of the strongest risk factors for prostate cancer is a family history of the disease. Germline mutations in the breast cancer predisposition gene 2 (BRCA2) are the genetic events known to date that confer the highest risk of prostate cancer (8.6-fold in men ≤65 years). Although the role of BRCA2 and BRCA1 in prostate tumorigenesis remains unrevealed, deleterious mutations in both genes have been associated with more aggressive disease and poor clinical outcomes. The increasing incidence of prostate cancer worldwide supports the need for new methods to predict outcome and identify patients with potentially lethal forms of the disease. As we present here, BRCA germline mutations, mainly in the BRCA2 gene, are one of those predictive factors. We will also discuss the implications of these mutations in the management of prostate cancer and hypothesize on the potential for the development of strategies for sporadic cases with similar characteristics.

Prostate cancer as a model system for genetic diversity in tumors

This chapter will summarize novel understandings of the early molecular events in prostatic carcinogenesis that may underlie both the genetic and clinical heterogeneity. Areas covered include preneoplasia, stem cell concepts, telomere abnormalities, and the nature of tumor-stromal interactions. The oncogenomics of prostate cancer is reviewed with emphasis on androgen signaling, ETS gene family aberrations, and PTEN deletion. The notion that "field cancerization," coupled with genomic instability may explain both the occurrence of multifocal disease, and the recent observations of genetic diversity of ERG alteration in individual tumors are discussed. Collectively, genomic studies are rapidly moving human prostate cancer closer to the promise of personalized medicine, so that specific genetic profiles of individual tumors will determine the best therapeutic approaches.

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.

p53 Regulates insulin-like growth factor-I receptor gene expression in uterine serous carcinoma and predicts responsiveness to an insulin-like growth factor-I receptor-directed targeted therapy

The role of the insulin-like growth factors (IGF) in endometrial cancer has been well established. The IGF-I receptor (IGF-IR), which mediates the biological actions of IGF-I, is usually overexpressed in endometrial tumours. Uterine serous carcinoma (USC) constitutes a defined histological category among endometrial cancers. Mutation of the p53 gene appears early in the course of the disease and is considered a key event in the initiation of USC. The aim of the present study was to evaluate the potential interactions between p53 and the IGF-IR in USC. In addition, we investigated the role of p53 as a biomarker in IGF-IR targeted therapies. Immunohistochemical analysis in a collection of 35 USC specimens revealed that IGF-IR is highly expressed in primary and metastatic USC. Likewise, p53 was expressed in 85.7% of primary tumours and 100% of metastases. A significant negative correlation between p53 expression and survival was noticed. In addition, using USC-derived cell lines we provide evidence that p53 regulates IGF-IR gene expression via a mechanism that involves repression of the IGF-IR promoter. We show that the mechanism of action of p53 involves interaction with zinc finger protein Sp1, a potent transactivator of the IGF-IR gene. Finally, we demonstrate that USC tumours overexpressing p53 are more likely to benefit from anti-IGF-IR therapies. In summary, we provide evidence that p53 regulates IGF-IR gene expression in USC cells via a mechanism that involves repression of the IGF-IR promoter. The interplay between the p53 and IGF-I signalling pathways is of major basic and translational relevance.

Plasma and tissue insulin-like growth factor-I receptor (IGF-IR) as a prognostic marker for prostate cancer and anti-IGF-IR agents as novel therapeutic strategy for refractory cases: a review

Cancer database analysis indicates that prostate cancer is one of the most seen cancers in men meanwhile composing the leading cause of morbidity and mortality among developed countries. Current available therapies are surgery, radiotherapy and androgene ablation for prostate carcinoma. The response rate is as high nearly 90% however, most of these recur or become refractory and androgene independent (AI). Therefore recent studies intensified on molecular factors playing role on development of prostate carcinoma and novel treatment strategies targetting these factors and their receptors. Insulin-like growth factor-I (IGF-I) and its primary receptor insulin-like growth factor receptor-I (IGF-IR) are among these factors. Biologic functions and role in malign progression are primarily achieved via IGF-IR which is a type 2 tyrosine kinase receptor. IGF-IR plays an important role in mitogenesis, angiogenesis, transformation, apoptosis and cell motility. It also generates intensive proliferative signals leading to carcinogenesis in prostate tissue. So IGF-IR and its associated signalling system have provoked considerable interest over recent years as a novel therapeutic target in cancer. In this paper it is aimed to sum up the lately published literature searching the relation of IGF-IR and prostate cancer in terms of incidence, pathologic features, and prognosis. This is followed by a discussion of the different possible targets within the IGF-1R system, and drugs developed to interact at each target. A systems-based approach is then used to review the in vitro and in vivo data in the published literature of the following compounds targeting IGF-1R components using specific examples: growth hormone releasing hormone antagonists (e.g. JV-1-38), growth hormone receptor antagonists (e.g. pegvisomant), IGF-1R antibodies (e.g. CP-751,871, AVE1642/EM164, IMC-A12, SCH-717454, BIIB022, AMG 479, MK-0646/h7C10), and IGF-1R tyrosine kinase inhibitors (e.g. BMS-536942, BMS-554417, NVP-AEW541, NVP-ADW742, AG1024, potent quinolinyl-derived imidazo (1,5-a)pyrazine PQIP, picropodophyllin PPP, nordihydroguaiaretic acid Insm-18/NDGA). And the other end point is to yield an overview on the recent progress about usage of this receptor as a novel anticancer agent of targeted therapies in treatment of prostate carcinoma.

Regulation of E2Fs and senescence by PML nuclear bodies

The tumor suppressor PML (promyelocytic leukemia protein) regulates cellular senescence and terminal differentiation, two processes that implicate a permanent exit from the cell cycle. Here, we show that the mechanism by which PML induces a permanent cell cycle exit and activates p53 and senescence involves a recruitment of E2F transcription factors bound to their promoters and the retinoblastoma (Rb) proteins to PML nuclear bodies enriched in heterochromatin proteins and protein phosphatase 1α. Blocking the functions of the Rb protein family or adding back E2Fs to PML-expressing cells can rescue their defects in E2F-dependent gene expression and cell proliferation, inhibiting the senescent phenotype. In benign prostatic hyperplasia, a neoplastic disease that displays features of senescence, PML was found to be up-regulated and forming nuclear bodies. In contrast, PML bodies were rarely visualized in prostate cancers. The newly defined PML/Rb/E2F pathway may help to distinguish benign tumors from cancers, and suggest E2F target genes as potential targets to induce senescence in human tumors.

Castration resistance in human prostate cancer is conferred by a frequently occurring androgen receptor splice variant

Progression of prostate cancer following castration is associated with increased androgen receptor (AR) expression and signaling despite AR blockade. Recent studies suggest that these activities are due to the generation of constitutively active AR splice variants, but the mechanisms by which these splice variants could mediate such effects are not fully understood. Here we have identified what we believe to be a novel human AR splice variant in which exons 5, 6, and 7 are deleted (ARv567es) and demonstrated that this variant can contribute to cancer progression in human prostate cancer xenograft models in mice following castration. We determined that, in human prostate cancer cell lines, ARv567es functioned as a constitutively active receptor, increased expression of full-length AR (ARfl), and enhanced the transcriptional activity of AR. In human xenografts, human prostate cancer cells transfected with ARv567es cDNA formed tumors that were resistant to castration. Furthermore, the ratio of ARv567es to ARfl expression within the xenografts positively correlated with resistance to castration. Importantly, we also detected ARv567es frequently in human prostate cancer metastases. In summary, these data indicate that constitutively active AR splice variants can contribute to the development of castration-resistant prostate cancers and may serve as biomarkers for patients who are likely to suffer from early recurrence and are candidates for therapies directly targeting the AR rather than ligand.

Uncovering packaging features of co-regulated modules based on human protein interaction and transcriptional regulatory networks

Background

Network co-regulated modules are believed to have the functionality of packaging multiple biological entities, and can thus be assumed to coordinate many biological functions in their network neighbouring regions.

Results

Here, we weighted edges of a human protein interaction network and a transcriptional regulatory network to construct an integrated network, and introduce a probabilistic model and a bipartite graph framework to exploit human co-regulated modules and uncover their specific features in packaging different biological entities (genes, protein complexes or metabolic pathways). Finally, we identified 96 human co-regulated modules based on this method, and evaluate its effectiveness by comparing it with four other methods.

Conclusions

Dysfunctions in co-regulated interactions often occur in the development of cancer. Therefore, we focussed on an example co-regulated module and found that it could integrate a number of cancer-related genes. This was extended to causal dysfunctions of some complexes maintained by several physically interacting proteins, thus coordinating several metabolic pathways that directly underlie cancer.

Progression to metastatic stage in a cellular model of prostate cancer is associated with methylation of the androgen receptor gene and transcriptional suppression of the insulin-like growth factor-I receptor gene

The progression of prostate cancer from an organ-confined, androgen-sensitive disease to a metastatic one is associated with dysregulation of androgen receptor (AR)-regulated target genes and with a decrease in insulin-like growth factor-I receptor (IGF1R) expression. DNA methylation of CpG islands is an epigenetic mechanism associated with gene silencing. Recent studies have demonstrated that methylation occurs early in prostate carcinogenesis and, furthermore, may contribute to androgen independence. The methylation status of the AR and IGF1R genes was evaluated in a series of prostate cancer cell lines corresponding to early (benign) and advanced (metastatic) stages of the disease. Results of 5-Aza-2'-deoxycytidine (5-Aza) experiments, methylation-specific PCR, and sodium bisulfite-direct DNA sequencing revealed that the AR promoter is hypermethylated in metastatic M12, but not in benign P69, cells. On the other hand, no methylation was seen in the IGF1R promoter at any stage of the disease. We show, however, that 5-Aza treatment, which caused demethylation of the AR promoter, led to a significant increase in IGF1R mRNA levels, whereas addition of the AR inhibitor flutamide decreased the IGF1R mRNA levels to basal values measured prior to the 5-Aza treatment. Given that the IGF1R gene has been identified as a downstream target for AR action, our data is consistent with a model in which the AR gene undergoes methylation during progression of the disease, leading to dysregulation of AR targets, including the IGF1R gene, at advanced metastatic stages.

Usefulness of the top-scoring pairs of genes for prediction of prostate cancer progression

Prediction of cancer progression after radical prostatectomy is one of the most challenging problems in the management of prostate cancer. Gene-expression profiling is widely used to identify genes associated with such progression. Usually candidate genes are identified according to a gene-by-gene comparison of expression. Recent reports suggested that relative expression of a gene pair more efficiently predicts cancer progression than single-gene analysis does. The top-scoring pair (TSP) algorithm classifies phenotypes according to the relative expression of a pair of genes. We applied the TSP approach to predict, which patients would experience systemic tumor progression after radical prostatectomy. Relative expression of TPD52L2/SQLE and CEACAM1/BRCA1 gene pairs identified those patients with more than 99% specificity but relatively low sensitivity (approximately 10%). These two gene pairs were validated in three independent data sets. In addition, combining two pairs of genes improved sensitivity without compromising specificity. Functional annotation of the TSP genes showed that they cluster by a limited number of biological functions and pathways, suggesting that relatively lower expression of genes from specific pathways can predict cancer progression. In conclusion, comparative analysis of the expression of two genes may be a simple and effective classifier for prediction of prostate cancer progression. In summary, the TSP approach can be used to identify patients whose prostate cancer will progress after they undergo radical prostatectomy. Two gene pairs can predict which men would experience progression to the metastatic form of the disease. However, because our analysis was based on a relatively small number of genes, a larger study will be needed to identify the best predictors of disease outcome overall.

Immunohistochemical expression of BRCA1 and lethal prostate cancer

BRCA1 functions as a tumor suppressor; recent work suggests that BRCA1 may also induce cell cycle arrest to allow for DNA repair. We hypothesized that BRCA1 expression in prostate tumor tissue may be associated with prostate cancer progression through regulation of the cell cycle. We used immunohistochemistry to evaluate BRCA1 protein expression in archival tumor samples from 393 prostate cancer cases in the Physicians' Health Study. The men were followed prospectively from diagnosis to development of metastases and mortality. Fifteen percent of tumors stained positive for BRCA1. BRCA1-positive tumors had substantially increased tumor proliferation index compared with negative tumors (47.0 Ki67-positive nuclei versus 10.3, P = 0.0016) and were more likely to develop lethal cancer compared with BRCA1-negative tumors (hazard ratio, 4.6; 95% confidence interval, 2.4-8.7). These findings strengthen the hypothesis that BRCA1 plays a role in cell cycle control and show that BRCA1 is a marker of clinical prostate cancer prognosis. Cancer Res; 70(8); 3136-9. (c)2010 AACR.

Targeting the IGF1 axis in cancer proliferation

The IGF network of ligands, cell-surface receptors and IGF-binding proteins has important roles at multiple levels, including the cellular, organ and organism levels. The IGF system mediates growth, differentiation and developmental processes, and is also involved in various metabolic activities. Dysregulation of IGF system expression and action is linked to diverse pathologies, ranging from growth deficits to cancer development. Targeting of the IGF axis emerged in recent years as a promising therapeutic approach in conditions in which the IGF system is involved. Specific IGF1 receptor (IGF1R) targeting, in particular, produced the best experimental and clinical results so far, and generated significant optimism in the field. This review provides a basic analysis of the role of the IGF1R in cancer biology and explores the functional interactions between the IGF signaling pathways and various cancer genes (e.g., oncogenes, tumor suppressors). In addition, we review a number of specific malignancies in which the IGF system is involved and summarize recent data on preclinical and clinical studies employing IGF1R-targeted modalities.