Insulin receptor isoforms A and B as well as insulin receptor substrates-1 and -2 are differentially expressed in prostate cancer

Insulin receptor alternative splicing in breast and prostate cancer

Cancer etiology represents an intricate, multifactorial orchestration where metabolically associated insulin-like growth factors (IGFs) and insulin foster cellular proliferation and growth throughout tumorigenesis. The insulin receptor (IR) exhibits two splice variants arising from alternative mRNA processing, namely IR-A, and IR-B, with remarkable distribution and biological effects disparities. This insightful review elucidates the structural intricacies, widespread distribution, and functional significance of IR-A and IR-B. Additionally, it explores the regulatory mechanisms governing alternative splicing processes, intricate signal transduction pathways, and the intricate association linking IR-A and IR-B splicing variants to breast and prostate cancer tumorigenesis. Breast cancer and prostate cancer are the most common malignant tumors with the highest incidence rates among women and men, respectively. These findings provide a promising theoretical framework for advancing preventive strategies, diagnostic modalities, and therapeutic interventions targeting breast and prostate cancer.

Insulin Receptor Isoforms and Insulin Growth Factor-like Receptors: Implications in Cell Signaling, Carcinogenesis, and Chemoresistance

This comprehensive review thoroughly explores the intricate involvement of insulin receptor (IR) isoforms and insulin-like growth factor receptors (IGFRs) in the context of the insulin and insulin-like growth factor (IGF) signaling (IIS) pathway. This elaborate system encompasses ligands, receptors, and binding proteins, giving rise to a wide array of functions, including aspects such as carcinogenesis and chemoresistance. Detailed genetic analysis of IR and IGFR structures highlights their distinct isoforms, which arise from alternative splicing and exhibit diverse affinities for ligands. Notably, the overexpression of the IR-A isoform is linked to cancer stemness, tumor development, and resistance to targeted therapies. Similarly, elevated IGFR expression accelerates tumor progression and fosters chemoresistance. The review underscores the intricate interplay between IRs and IGFRs, contributing to resistance against anti-IGFR drugs. Consequently, the dual targeting of both receptors could present a more effective strategy for surmounting chemoresistance. To conclude, this review brings to light the pivotal roles played by IRs and IGFRs in cellular signaling, carcinogenesis, and therapy resistance. By precisely modulating these receptors and their complex signaling pathways, the potential emerges for developing enhanced anti-cancer interventions, ultimately leading to improved patient outcomes.

Primary Total Prostate Cryoablation for Localized High-Risk Prostate Cancer: 10-Year Outcomes and Nomograms

The role of prostate cryoablation was still uncertain for patients with high-risk prostate cancer (PC). This study was designed to investigate 10-year disease-free survival and establish a nomogram in localized high-risk PC patients. Between October 2008 and December 2020, 191 patients with high-risk PC who received primary total prostate cryoablation (PTPC) were enrolled. The primary endpoint was biochemical recurrence (BCR), defined using Phoenix criteria. The performance of pre-operative and peri-operative nomograms was determined using the Harrell concordance index (C-index). Among the cohort, the median age and PSA levels at diagnosis were 71 years and 12.3 ng/mL, respectively. Gleason sum 8-10, stage ≥ T3a, and PSA > 20 ng/mL were noted in 27.2%, 74.4%, and 26.2% of patients, respectively. During the median follow-up duration of 120.4 months, BCR-free rates at 1, 3, 5, and 10 years were 92.6%, 76.6%, 66.7%, and 50.8%, respectively. The metastasis-free, cancer-specific, and overall survival rates were 89.5%, 97.4%, and 90.5% at 10 years, respectively. The variables in the pre-operative nomogram for BCR contained PSA at diagnosis, clinical stage, and Gleason score (C-index: 0.73, 95% CI, 0.67-0.79). The variables in the peri-operative nomogram for BCR included PSA at diagnosis, Gleason score, number of cryoprobes used, and PSA nadir (C-index: 0.83, 95% CI, 0.78-0.88). In conclusion, total prostate cryoablation appears to be an effective treatment option for selected men with high-risk PC. A pre-operative nomogram can help select patients suitable for cryoablation. A peri-operative nomogram signifies the importance of the ample use of cryoprobes and helps identify patients who may need early salvage treatment.

Inceptor correlates with markers of prostate cancer progression and modulates insulin/IGF1 signaling and cancer cell migration

OBJECTIVE

The insulin/insulin-like growth factor 1 (IGF1) pathway is emerging as a crucial component of prostate cancer progression. Therefore, we investigated the role of the novel insulin/IGF1 signaling modulator inceptor in prostate cancer.

METHODS

We analyzed the expression of inceptor in human samples of benign prostate epithelium and prostate cancer. Further, we performed signaling and functional assays using prostate cancer cell lines.

RESULTS

We found that inceptor was expressed in human benign and malignant prostate tissue and its expression positively correlated with various genes of interest, including genes involved in androgen signaling. In vitro, total levels of inceptor were increased upon androgen deprivation and correlated with high levels of androgen receptor in the nucleus. Inceptor overexpression was associated with increased cell migration, altered IGF1R trafficking and higher IGF1R activation.

CONCLUSIONS

Our in vitro results showed that inceptor expression was associated with androgen status, increased migration, and IGF1R signaling. In human samples, inceptor expression was significantly correlated with markers of prostate cancer progression. Taken together, these data provide a basis for investigation of inceptor in the context of prostate cancer.

Advances in the Prevention and Treatment of Obesity-Driven Effects in Breast Cancers

Obesity and associated chronic inflammation were shown to facilitate breast cancer (BC) growth and metastasis. Leptin, adiponectin, estrogen, and several pro-inflammatory cytokines are involved in the development of obesity-driven BC through the activation of multiple oncogenic and pro-inflammatory pathways. The aim of this study was to assess the reported mechanisms of obesity-induced breast carcinogenesis and effectiveness of conventional and complementary BC therapies. We screened published original articles, reviews, and meta-analyses that addressed the involvement of obesity-related signaling mechanisms in BC development, BC treatment/prevention approaches, and posttreatment complications. PubMed, Medline, eMedicine, National Library of Medicine (NLM), and ReleMed databases were used to retrieve relevant studies using a set of keywords, including "obesity," "oncogenic signaling pathways," "inflammation," "surgery," "radiotherapy," "conventional therapies," and "diet." Multiple studies indicated that effective BC treatment requires the involvement of diet- and exercise-based approaches in obese postmenopausal women. Furthermore, active lifestyle and diet-related interventions improved the patients' overall quality of life and minimized adverse side effects after traditional BC treatment, including postsurgical lymphedema, post-chemo nausea, vomiting, and fatigue. Further investigation of beneficial effects of diet and physical activity may help improve obesity-linked cancer therapies.

Alternative RNA Splicing Defects in Pediatric Cancers: New Insights in Tumorigenesis and Potential Therapeutic Vulnerabilities

BACKGROUND

Compared to adult cancers, pediatric cancers are uniquely characterized by a genomically stable landscape and lower tumor mutational burden. However, alternative splicing, a global cellular process that produces different mRNA/protein isoforms from a single mRNA transcript, has been increasingly implicated in the development of pediatric cancers.

DESIGN

We review the current literature on the role of alternative splicing in adult cancer, cancer predisposition syndromes, and pediatric cancers. We also describe multiple splice variants identified in adult cancers and confirmed through comprehensive genomic profiling in our institutional cohort of rare, refractory and relapsed pediatric and adolescent young adult cancer patients. Finally, we summarize the contributions of alternative splicing events to neoantigens and chemoresistance and prospects for splicing-based therapies.

RESULTS

Published dysregulated splicing events can be categorized as exon inclusion, exon exclusion, splicing factor upregulation, or splice site alterations. We observe these phenomena in cancer predisposition syndromes (Lynch syndrome, Li-Fraumeni syndrome, CHEK2) and pediatric leukemia (B-ALL), sarcomas (Ewing sarcoma, rhabdomyosarcoma, osteosarcoma), retinoblastoma, Wilms tumor, and neuroblastoma. Within our institutional cohort, we demonstrate splice variants in key regulatory genes (CHEK2, TP53, PIK3R1, MDM2, KDM6A, NF1) that resulted in exon exclusion or splice site alterations, which were predicted to impact functional protein expression and promote tumorigenesis. Differentially spliced isoforms and splicing proteins also impact neoantigen creation and treatment resistance, such as imatinib or glucocorticoid regimens. Additionally, splice-altering strategies with the potential to change the therapeutic landscape of pediatric cancers include antisense oligonucleotides, adeno-associated virus gene transfers, and small molecule inhibitors.

CONCLUSIONS

Alternative splicing plays a critical role in the formation and growth of pediatric cancers, and our institutional cohort confirms and highlights the broad spectrum of affected genes in a variety of cancers. Further studies that elucidate the mechanisms of disease-inducing splicing events will contribute toward the development of novel therapeutics.

Insulin signaling, androgen receptor and PSMA immunohistochemical analysis by semi-automated tissue microarray in prostate cancer with diabetes (DIAMOND study)

In the last years, many studies have highlighted the hypothesis that diabetes and hyperglycemia could be relevant for prostate cancer (PC) development and progression. We aimed to identify the prognostic value of tissue expression of androgen receptor (AR), Prostate-Specific Membrane Antigen (PSMA), Ki-67, insulin receptors (IR)  α and β, insulin growth factor-1 (IGF-1) receptor, in patients with PC and to evaluate their association with diabetes. We retrospectively collected data from 360 patients who underwent radical prostatectomy for PC or surgery for benign prostatic hyperplasia (BPH), between 2010 and 2020. We constructed tissue microarray for immunohistochemistry (IHC) analysis. In the final cohort (76 BPH and 284 PC), 57 (15.8%) patients had diabetes, 17 (22.37%) in BPH and 40 (14.08%) in PC (P = 0.08). IR-α was more expressed in patients with PC compared to the BPH Group (95.96% vs 4.04%; P <0.01). We found that AR was associated with increased risk of International Society of Urological Pathology (ISUP) score ≥4 (OR: 2.2; P <0.05), higher association with Ki-67 (OR: 2.2; P <0.05) and IR-α (OR: 5.7; P <0.05); IGF-1 receptor was associated with PSMA (OR: 2.8; P <0.05), Ki-67 (OR: 3.5; P <0.05) and IR-β (OR: 5.1; P <0.05). Finally, IGF-1 receptor was predictive of ISUP ≥ 4 (OR: 16.5; P =0.017) in patients with PC and diabetes. In the present study we highlighted how prostate cancer patients have a different protein expression in the tissue. This expression, and in particular that relating to IGF-1R, is associated with greater tumor aggressiveness in those patients with diabetes. We suppose that these results are attributable to an alteration of the insulin signal which therefore determines a greater mitogenic activity that can influence tumor progression.

Insulin Receptor in Pancreatic Cancer-Crown Witness in Cross Examination

BACKGROUND

The proximity of pancreatic cancer (PDAC) to the physiological source of the growth promoting hormone insulin might be exploited by this highly malignant cancer entity. We investigated if (I) PDACs express the insulin receptor (IR) in cancer cells and cancer vasculature, (II) if IR correlates with clinicopathological patient characteristics, including survival, and hence is involved in PDAC biology, (III) if IR is already expressed in precursor lesions, if (IV) the IGF1 receptor (IGF1R) is associated with clinicopathological patient characteristics and survival and (V) is linked to IR expression.

METHODS

160 PDAC samples were examined for IR and IGF1R expression by immunohistochemistry. A modified HistoScore was correlated with clinicopathological characteristics and survival.

RESULTS

IR overexpression was already observed in pancreatic intraepithelial neoplasia. Furthermore, it was more frequently observed in advanced disease and associated with distant metastasis, UICC stage, lymphatic invasion and an increased lymph node ratio, but without impacting survival in the end. IGF1R expression was not associated with clinicopathological parameters or survival, in contrast to former paradigms.

CONCLUSIONS

We hypothesize that the close proximity to the pancreatic islets might be advantageous for cancer growth at first, but it experiences self-limitation due to surgical removal or local destruction following accelerated cancer growth.

SRSF-1 and microvessel density immunohistochemical analysis by semi-automated tissue microarray in prostate cancer patients with diabetes (DIAMOND study)

OBJECTIVE

To study the association between insulin receptors (isoforms α and β), insulin growth factor-1 (IGF1) and serine/arginine splicing factor 1 (SRSF-1) in patients with prostate cancer (PC) and diabetes.

MATERIALS AND METHODS

We retrospectively analyzed data from 368 patients who underwent surgery for PC or benign prostatic hyperplasia (BPH) between 2010 and 2020 at the Department of Urology, University of Catania. Tissue microarray slides were constructed and they were stained for androgen receptor (AR), insulin receptor-α and -β, IGF1 (IGF1-R), Ki-67, and prostate specific membrane antigen (PSMA) expression using validated score.

RESULTS

The final cohort was represented by 100 patients with BPH and 268 with PC, with a median age of 68 years. We found that SRSF-1 expression was associated with AR (odds ratio [OR]: 1.66), PSMA (OR: 2.13), Ki-67 (OR: 5.99), insulin receptor (IR)-α (OR: 2.38), IR-β (OR: 3.48), IGF1-R (OR: 1.53), and microvascular density (MVD) was associated with PSMA (OR: 3.44), Ki-67 (OR: 2.23), IR-α (OR: 2.91), IR-β (OR: 3.02), IGF1-R (OR: 2.95), and SRSF-1 (OR: 2.21). In the sub cohort of PC patients, we found that SRSF-1 expression was associated with AR (OR: 2.34), Ki-67 (OR: 6.77), IR-α (OR: 2.7), and MVD (OR: 1.98). At the Kaplan-Meier analysis, SRSF-1⁺ patients had worse 5- and 9-year biochemical recurrence (36% and 6%) respect to SRSF-1^- (67% and 7%; p < .01) and similarly MVD⁺ patients (44% and 7%) respect to MVD^- (64% and 8%; p < .01). Restricting the analysis only in patients with PC and diabetes, we found that SRSF-1⁺ was associated with Ki-67⁺ (OR: 8.75; p < .05) and MVD⁺ (OR: 7.5; p < .05).

CONCLUSIONS

PC exhibits widespread heterogeneity in protein expression. In particular, the expressions of the SRSF-1 protein and of the MVD are associated with a worse prognosis and in particular with a greater cell proliferation. These results, although preliminary, may offer new future scientific insights with the aim of highlighting possible genetic alterations linked to a greater expression of SRSF-1 and associated with a worse prognosis.

Hyperinsulinemia in Obesity, Inflammation, and Cancer

The relative insufficiency of insulin secretion and/or insulin action causes diabetes. However, obesity and type 2 diabetes mellitus can be associated with an absolute increase in circulating insulin, a state known as hyperinsulinemia. Studies are beginning to elucidate the cause-effect relationships between hyperinsulinemia and numerous consequences of metabolic dysfunctions. Here, we review recent evidence demonstrating that hyperinsulinemia may play a role in inflammation, aging and development of cancers. In this review, we will focus on the consequences and mechanisms of excess insulin production and action, placing recent findings that have challenged dogma in the context of the existing body of literature. Where relevant, we elaborate on the role of specific signal transduction components in the actions of insulin and consequences of chronic hyperinsulinemia. By discussing the involvement of hyperinsulinemia in various metabolic and other chronic diseases, we may identify more effective therapeutics or lifestyle interventions for preventing or treating obesity, diabetes and cancer. We also seek to identify pertinent questions that are ripe for future investigation.

Influence of Obesity in the miRNome: miR-4454, a Key Regulator of Insulin Response Via Splicing Modulation in Prostate

CONTEXT

Obesity is a major health problem associated with severe comorbidities, including type 2 diabetes and cancer, wherein microRNAs (miRNAs) might be useful as diagnostic/prognostic tools or therapeutic targets.

OBJECTIVE

To explore the differential expression pattern of miRNAs in obesity and their putative role in obesity-related comorbidities such as insulin resistance.

METHODS

An Affymetrix-miRNA array was performed in plasma samples from normoweight (n = 4/body mass index < 25) and obese subjects (n = 4/body mass index > 30). The main changes were validated in 2 independent cohorts (n = 221/n = 18). Additionally, in silico approaches were performed and in vitro assays applied in tissue samples and prostate (RWPE-1) and liver (HepG2) cell-lines.

RESULTS

A total of 26 microRNAs were altered (P < 0.01) in plasma of obese subjects compared to controls using the Affymetrix-miRNA array. Validation in ampler cohorts revealed that miR-4454 levels were consistently higher in obesity, associated with insulin-resistance (Homeostatic Model Assessment of Insulin Resistance/insulin) and modulated by medical (metformin/statins) and surgical (bariatric surgery) strategies. miR-4454 was highly expressed in prostate and liver tissues and its expression was increased in prostate and liver cells by insulin. In vitro, overexpression of miR-4454 in prostate cells resulted in decreased expression levels of INSR, GLUT4, and phosphorylation of AMPK/AKT/ERK, as well as in altered expression of key spliceosome components (ESRP1/ESRP2/RBM45/RNU2) and insulin-receptor splicing variants.

CONCLUSIONS

Obesity was associated to an alteration of the plasmatic miRNA landscape, wherein miR-4454 levels were higher, associated with insulin-resistance and modulated by obesity-controlling interventions. Insulin regulated miR-4454, which, in turn may impair the cellular response to insulin, in a cell type-dependent manner (i.e., prostate gland), by modulating the splicing process.

Endocrinology of the Aging Prostate: Current Concepts

Benign prostate hyperplasia (BPH), one of the most common diseases in older men, adversely affects quality-of-life due to the presence of low urinary tract symptoms (LUTS). Numerous data support the presence of an association between BPH-related LUTS (BPH-LUTS) and metabolic syndrome (MetS). Whether hormonal changes occurring in MetS play a role in the pathogenesis of BPH-LUTS is a debated issue. Therefore, this article aimed to systematically review the impact of hormonal changes that occur during aging on the prostate, including the role of sex hormones, insulin-like growth factor 1, thyroid hormones, and insulin. The possible explanatory mechanisms of the association between BPH-LUTS and MetS are also discussed. In particular, the presence of a male polycystic ovarian syndrome (PCOS)-equivalent may represent a possible hypothesis to support this link. Male PCOS-equivalent has been defined as an endocrine syndrome with a metabolic background, which predisposes to the development of type II diabetes mellitus, cardiovascular diseases, prostate cancer, BPH and prostatitis in old age. Its early identification would help prevent the onset of these long-term complications.

Hyperinsulinaemia in cancer

Elevated circulating insulin levels are frequently observed in the setting of obesity and early type 2 diabetes, as a result of insensitivity of metabolic tissues to the effects of insulin. Higher levels of circulating insulin have been associated with increased cancer risk and progression in epidemiology studies. Elevated circulating insulin is believed to be a major factor linking obesity, diabetes and cancer. With the development of targeted cancer therapies, insulin signalling has emerged as a mechanism of therapeutic resistance. Although metabolic tissues become insensitive to insulin in the setting of obesity, a number of mechanisms allow cancer cells to maintain their ability to respond to insulin. Significant progress has been made in the past decade in understanding the insulin receptor and its signalling pathways in cancer, and a number of lessons have been learnt from therapeutic failures. These discoveries have led to numerous clinical trials that have aimed to reduce the levels of circulating insulin and to abrogate insulin signalling in cancer cells. With the rising prevalence of obesity and diabetes worldwide, and the realization that hyperinsulinaemia may contribute to therapeutic failures, it is essential to understand how insulin and insulin receptor signalling promote cancer progression.

Characterization of Hormone-Dependent Pathways in Six Human Prostate-Cancer Cell Lines: A Gene-Expression Study

Prostate cancer (PCa), the most incident cancer in men, is tightly regulated by endocrine signals. A number of different PCa cell lines are commonly used for in vitro experiments, but these are of diverse origin, and have very different cell-proliferation rates and hormone-response capacities. By analyzing the gene-expression pattern of main hormone pathways, we systematically compared six PCa cell lines and parental primary cells. We compared these cell lines (i) with each other and (ii) with PCa tissue samples from 11 patients. We found major differences in the gene-expression levels of androgen, insulin, estrogen, and oxysterol signaling between PCa tissue and cell lines, and between different cell lines. Our systematic characterization gives researchers a solid basis to choose the appropriate PCa cell model for the hormone pathway of interest.

Transcript Levels of Aldo-Keto Reductase Family 1 Subfamily C (AKR1C) Are Increased in Prostate Tissue of Patients with Type 2 Diabetes

Aldo-keto reductase family 1 (AKR1) enzymes play a crucial role in diabetic complications. Since type 2 diabetes (T2D) is associated with cancer progression, we investigated the impact of diabetes on AKR1 gene expression in the context of prostate cancer (PCa) development. In this study, we analyzed benign (BEN) prostate and PCa tissue of patients with and without T2D. Furthermore, to replicate hyperglycemia in vitro, we treated the prostate adenocarcinoma cell line PC3 with increasing glucose concentrations. Gene expression was quantified using real-time qPCR. In the prostate tissue of patients with T2D, AKR1C1 and AKR1C2 transcripts were higher compared to samples of patients without diabetes. In PC3 cells, high glucose treatment induced the gene expression levels of AKR1C1, C2, and C3. Furthermore, both in human tissue and in PC3 cells, the transcript levels of AKR1C1, C2, and C3 showed positive associations with oncogenes, which are involved in proliferation processes and HIF1α and NFκB pathways. These results indicate that in the prostate glands of patients with T2D, hyperglycemia could play a pivotal role by inducing the expression of AKR1C1, C2, and C3. The higher transcript level of AKR1C was furthermore associated with upregulated HIF1α and NFκB pathways, which are major drivers of PCa carcinogenesis.

Insulin Receptor Substrate-1 (IRS-1) and IRS-2 expression levels are associated with prognosis in non-small cell lung cancer (NSCLC)

The insulin-like growth factor-1 (IGF-1) signaling pathway has been implicated in non-small cell lung cancer (NSCLC) outcomes and resistance to targeted therapies. However, little is known regarding the molecular mechanisms by which this pathway contributes to the biology of NSCLC. The insulin receptor substrate (IRS) proteins are cytoplasmic adaptor proteins that signal downstream of the IGF-1R and determine the functional outcomes of this signaling pathway. In this study, we assessed the expression patterns of IRS-1 and IRS-2 in NSCLC to identify associations between IRS-1 and IRS-2 expression levels and survival outcomes in the two major histological subtypes of NSCLC, adenocarcinoma (ADC) and squamous cell carcinoma (SCC). High IRS-2 expression was significantly associated with decreased overall survival in adenocarcinoma (ADC) patients, whereas low IRS-1 cytoplasmic expression showed a trend toward association with decreased overall survival in squamous cell carcinoma (SCC) patients. Tumors with low IRS-1 and high IRS-2 expression were found to be associated with poor outcomes in ADC and SCC, indicating a potential role for IRS-2 in the aggressive behavior of NSCLC. Our results suggest distinct contributions of IRS-1 and IRS-2 to the biology of ADC and SCC that impact disease progression.

Tau and mTOR: The Hotspots for Multifarious Diseases in Alzheimer's Development

The hyperphosphorylation of tau protein and the overexpression of mTOR are considered to be the driving force behind Aβ plaques and Neurofibrillay Tangles (NFT's), hallmarks of Alzheimer's disease (AD). It is now evident that miscellaneous diseases such as Diabetes, Autoimmune diseases, Cancer, etc. are correlated with AD. Therefore, we reviewed the literature on the causes of AD and investigated the association of tau and mTOR with other diseases. We have discussed the role of insulin deficiency in diabetes, activated microglial cells, and dysfunction of blood-brain barrier (BBB) in Autoimmune diseases, Presenilin 1 in skin cancer, increased reactive species in mitochondrial dysfunction and deregulated Cyclins/CDKs in promoting AD pathogenesis. We have also discussed the possible therapeutics for AD such as GSK3 inactivation therapy, Rechaperoning therapy, Immunotherapy, Hormonal therapy, Metal chelators, Cell cycle therapy, γ-secretase modulators, and Cholinesterase and BACE 1-inhibitors which are thought to serve a major role in combating pathological changes coupled with AD. Recent research about the relationship between mTOR and aging and hepatic Aβ degradation offers possible targets to effectively target AD. Future prospects of AD aims at developing novel drugs and modulators that can potentially improve cell to cell signaling, prevent Aβ plaques formation, promote better release of neurotransmitters and prevent hyperphosphorylation of tau.

Insulin Enhances Migration and Invasion in Prostate Cancer Cells by Up-Regulation of FOXC2

Androgen deprivation therapy (ADT) is the standard treatment for advanced prostate cancer (PCa), yet many patients relapse with lethal metastatic disease. With this loss of androgens, increased cell plasticity has been observed as an adaptive response to ADT. This includes gain of invasive and migratory capabilities, which may contribute to PCa metastasis. Hyperinsulinemia, which develops as a side-effect of ADT, has been associated with increased tumor aggressiveness and faster treatment failure. We investigated the direct effects of insulin in PCa cells that may contribute to this progression. We measured cell migration and invasion induced by insulin using wound healing and transwell assays in a range of PCa cell lines of variable androgen dependency (LNCaP, 22RV1, DuCaP, and DU145 cell lines). To determine the molecular events driving insulin-induced invasion we used transcriptomics, quantitative real time-PCR, and immunoblotting in three PCa cell lines. Insulin increased invasiveness of PCa cells, upregulating Forkhead Box Protein C2 (FOXC2), and activating key PCa cell plasticity mechanisms including gene changes consistent with epithelial-to-mesenchymal transition (EMT) and a neuroendocrine phenotype. Additionally, analysis of publicly available clinical PCa tumor data showed metastatic prostate tumors demonstrate a positive correlation between insulin receptor expression and the EMT transcription factor FOXC2. The insulin receptor is not suitable to target clinically however, our data shows that actions of insulin in PCa cells may be suppressed by inhibiting downstream signaling molecules, PI3K and ERK1/2. This study identifies for the first time, a mechanism for insulin-driven cancer cell motility and supports the concept that targeting insulin signaling at the level of the PCa tumor may extend the therapeutic efficacy of ADT.

Insulin Receptor Isoforms in Cancer

The insulin receptor (IR) mediates both metabolic and mitogenic effects especially when overexpressed or in clinical conditions with compensatory hyperinsulinemia, due to the metabolic pathway resistance, as obesity diabetes. In many cancers, IR is overexpressed preferentially as IR-A isoform, derived by alternative splicing of exon 11. The IR-A overexpression, and the increased IR-A:IR-B ratio, are mechanisms that promote the mitogenic response of cancer cells to insulin and IGF-2, which is produced locally by both epithelial and stromal cancer cells. In cancer IR-A, isoform predominance may occur for dysregulation at both mRNA transcription and post-transcription levels, including splicing factors, non-coding RNAs and protein degradation. The mechanisms that regulate IR isoform expression are complex and not fully understood. The IR isoform overexpression may play a role in cancer cell stemness, in tumor progression and in resistance to target therapies. From a clinical point of view, the IR-A overexpression in cancer may be a determinant factor for the resistance to IGF-1R target therapies for this issue. IR isoform expression in cancers may have the meaning of a predictive biomarker and co-targeting IGF-1R and IR-A may represent a new more efficacious treatment strategy.

Insulin glargine affects the expression of Igf-1r, Insr, and Igf-1 genes in colon and liver of diabetic rats

Objective(s):

The mitogenic effect of the analogous insulin glargine is currently under debate since several clinical studies have raised the possibility that insulin glargine treatment has a carcinogenic potential in different tissues. This study aimed to evaluate the Igf-1r, Insr, and Igf-1 gene expression in colon and liver of streptozotocin-induced diabetic rats in response to insulin glargine, neutral protamine Hagedorn (NPH) insulin, and metformin treatments.

Materials and Methods:

Male Wistar rats were induced during one week with streptozotocin to develop Type 2 Diabetes (T2D) and then randomly distributed into four groups. T2D rats included in the first group received insulin glargine, the second group received NPH insulin, the third group received metformin; finally, untreated T2D rats were included as the control group. All groups were treated for seven days; after the treatment, tissue samples of liver and colon were obtained. Quantitative PCR (qPCR) was performed to analyze the Igf-1r, Insr and Igf-1 gene expression in each tissue sample.

Results:

The liver tissue showed overexpression of the Insr and Igf-1r genes (P>0.001) in rats treated with insulin glargine in comparison with the control group. Similar results were observed for the Insr gene (P>0.011) in colonic tissue of rats treated with insulin glargine.

Conclusion:

These observations demonstrate that insulin glargine promote an excess of insulin and IGF-1 receptors in STZ-induced diabetic rats, which could overstimulate the mitogenic signaling pathways.

Gene expression of insulin receptor, insulin-like growth factor increases and insulin-like growth factor-binding protein-3 reduces with increase in prostate size in benign prostatic hyperplasia

INTRODUCTION

Although the role of insulin in the development of benign prostatic hyperplasia (BPH) is well established, there are no studies regarding alteration in the gene expression of components of insulin-signaling pathway and their association with prostate size in BPH. Hence, the study was designed to analyze the gene and protein expression of insulin receptor and its related components in patients with BPH.

MATERIALS AND METHODS

Twenty-seven BPH patients aged between 55 and 75 years were recruited in the study and prostatic tissues were obtained after transurethral resection of the prostate. Gene expression levels of Insulin receptor (IR), insulin receptor substrate (IRS), insulin-like growth factor (IGF) and insulin-like growth factor-binding protein-3 (IGFBP-3) were assessed by q-PCR.

RESULTS

Insulin receptor (IR-A and B) and insulin-like growth factors (IGF-1 and IGF-2) gene expression were significantly increased and IGFBP-3 gene expression was reduced in BPH patients with larger prostate size. Also, serum insulin was significantly increased and IGFBP-3 was significantly reduced in patients with larger prostate size.

CONCLUSION

Increased expression of IR-A, B and IGF-1, 2 genes and reduced IGFBP-3 gene expression was associated with larger prostate size in BPH.

IL-4 and IL-13 Receptor Signaling From 4PS to Insulin Receptor Substrate 2: There and Back Again, a Historical View

In this historical perspective, written in honor of Dr. William E. Paul, we describe the initial discovery of one of the dominant substrates for tyrosine phosphorylation stimulated by IL-4. We further describe how this “IL-4-induced phosphorylated substrate” (4PS) was characterized as a member of the insulin receptor substrate (IRS) family of large adaptor proteins that link IL-4 and insulin receptors to activation of the phosphatidyl-inositol 3′ kinase pathway as well as other downstream signaling pathways. The relative contribution of the 4PS/IRS pathway to the early models of IL-4-induced proliferation and suppression of apoptosis are compared to our more recent understanding of the complex interplay between positive and negative regulatory pathways emanating from members of the IRS family that impact allergic responses.

Viral insulin-like peptides activate human insulin and IGF-1 receptor signaling: A paradigm shift for host-microbe interactions

Viruses are the most abundant biological entities and carry a wide variety of genetic material, including the ability to encode host-like proteins. Here we show that viruses carry sequences with significant homology to several human peptide hormones including insulin, insulin-like growth factors (IGF)-1 and -2, FGF-19 and -21, endothelin-1, inhibin, adiponectin, and resistin. Among the strongest homologies were those for four viral insulin/IGF-1-like peptides (VILPs), each encoded by a different member of the family Iridoviridae VILPs show up to 50% homology to human insulin/IGF-1, contain all critical cysteine residues, and are predicted to form similar 3D structures. Chemically synthesized VILPs can bind to human and murine IGF-1/insulin receptors and stimulate receptor autophosphorylation and downstream signaling. VILPs can also increase glucose uptake in adipocytes and stimulate the proliferation of fibroblasts, and injection of VILPs into mice significantly lowers blood glucose. Transfection of mouse hepatocytes with DNA encoding a VILP also stimulates insulin/IGF-1 signaling and DNA synthesis. Human microbiome studies reveal the presence of these Iridoviridae in blood and fecal samples. Thus, VILPs are members of the insulin/IGF superfamily with the ability to be active on human and rodent cells, raising the possibility for a potential role of VILPs in human disease. Furthermore, since only 2% of viruses have been sequenced, this study raises the potential for discovery of other viral hormones which, along with known virally encoded growth factors, may modify human health and disease.

Androgen receptor overexpression in prostate cancer in type 2 diabetes

OBJECTIVE

While prostate cancer does not occur more often in men with diabetes, survival is markedly reduced in this patient group. Androgen signaling is a known and major driver for prostate cancer progression. Therefore, we analyzed major components of the androgen signaling chain and cell proliferation in relation to type 2 diabetes.

METHODS

Tumor content of 70 prostate tissue samples of men with type 2 diabetes and 59 samples of patients without diabetes was quantified by an experienced pathologist, and a subset of 51 samples was immunohistochemically stained for androgen receptor (AR). mRNA expression of AR, insulin receptor isoform A (IR-A) and B (IR-B), IGF-1 receptor (IGF1R), Cyp27A1 and Cyp7B1, PSA gene KLK3, PSMA gene FOLH1, Ki-67 gene MKI67, and estrogen receptor beta (ESR2) were analyzed by RT-qPCR.

RESULTS

AR mRNA and protein expression were associated with the tumor content only in men with diabetes. AR expression also correlated with downstream targets PSA (KLK3) and PSMA (FOLH1) and increased cell proliferation. Only in diabetes, AR expression was correlated to higher IR-A/IR-B ratio and lower IR-B/IGF1R ratio, thus, in favor of the mitogenic isoforms. Reduced Cyp27A1 and increased Cyp7B1 expressions in tumor suggest lower levels of protective estrogen receptor ligands in diabetes.

CONCLUSIONS

We report elevated androgen receptor signaling and activity presumably due to altered insulin/IGF-1 receptors and decreased levels of protective estrogen receptor ligands in prostate cancer in men with diabetes. Our results reveal new insights why these patients have a worse prognosis. These findings provide the basis for future clinical trials to investigate treatment response in patients with prostate cancer and diabetes.

Insulin Receptor Isoforms in Physiology and Disease: An Updated View

The insulin receptor (IR) gene undergoes differential splicing that generates two IR isoforms, IR-A and IR-B. The physiological roles of IR isoforms are incompletely understood and appear to be determined by their different binding affinities for insulin-like growth factors (IGFs), particularly for IGF-2. Predominant roles of IR-A in prenatal growth and development and of IR-B in metabolic regulation are well established. However, emerging evidence indicates that the differential expression of IR isoforms may also help explain the diversification of insulin and IGF signaling and actions in various organs and tissues by involving not only different ligand-binding affinities but also different membrane partitioning and trafficking and possibly different abilities to interact with a variety of molecular partners. Of note, dysregulation of the IR-A/IR-B ratio is associated with insulin resistance, aging, and increased proliferative activity of normal and neoplastic tissues and appears to sustain detrimental effects. This review discusses novel information that has generated remarkable progress in our understanding of the physiology of IR isoforms and their role in disease. We also focus on novel IR ligands and modulators that should now be considered as an important strategy for better and safer treatment of diabetes and cancer and possibly other IR-related diseases.

Diabetes drugs and the incidence of solid cancers: a survey of the current evidence

INTRODUCTION

The evaluation of the relationship between the use of antidiabetic drug and the occurrence of cancer is extremely challenging, both from the clinical and pharmacoepidemiological standpoint. This narrative review described the current evidence supporting a relationship between the use of antidiabetic drugs and the incidence of solid cancers. Areas covered: Data from pharmacoepidemiological studies on cancer incidence were presented for the main antidiabetic drugs and drug classes, including human insulin and insulin analogues, metformin, sulfonylureas, glinides, alpha-glucosidase inhibitors, thiazolidinediones, incretin mimetics, and sodium glucose co-transporter 2 inhibitors. The relationship between the use of antidiabetics and the incidence of solid cancer was described in strata by any cancer and by organ-specific cancer and by drug and by drug classes. Information supporting biological evidence and putative mechanisms were also provided. Expert opinion: The history of exploration of the relationship between antidiabetic drugs and the risk of solid cancers has showed several issues. Unrecognized biases and misinterpretations of study results have had important consequences that delayed the identification of actual risk and benefits of the use of antidiabetic drugs associated with cancer occurrence or progression. The lesson learned from the past should address the future research in this area, since in the majority of cases findings are controversial and confirmatory studies are warranted.

Pro-angiogenic Role of Insulin: From Physiology to Pathology

The underlying molecular mechanisms involve in the regulation of the angiogenic process by insulin are not well understood. In this review article, we aim to describe the role of insulin and insulin receptor activation on the control of angiogenesis and how these mechanisms can be deregulated in human diseases. Functional expression of insulin receptors and their signaling pathways has been described on endothelial cells and pericytes, both of the main cells involved in vessel formation and maturation. Consequently, insulin has been shown to regulate endothelial cell migration, proliferation, and in vitro tubular structure formation through binding to its receptors and activation of intracellular phosphorylation cascades. Furthermore, insulin-mediated pro-angiogenic state is potentiated by generation of vascular growth factors, such as the vascular endothelial growth factor, produced by endothelial cells. Additionally, diseases such as insulin resistance, obesity, diabetes, and cancer may be associated with the deregulation of insulin-mediated angiogenesis. Despite this knowledge, the underlying molecular mechanisms need to be elucidated in order to provide new insights into the role of insulin on angiogenesis.

Insulin Receptor Isoform Variations in Prostate Cancer Cells

Men who develop prostate cancer (PCa) increasingly have one of the co-morbidities associated with a Western lifestyle that are characterized by hyperinsulinemia, hyperglycemia and increased expression of insulin-like growth factors-I (IGF-I) and IGF-II. Each have been associated with poor prognosis and more aggressive cancers that exhibit increased metabolism and increased glucose uptake. The insulin receptor (IR) has two splice isoforms IR-A and IR-B: IR-A has a higher affinity for IGF-II comparable to that for insulin, whereas the IR-B isoform predominantly just binds to insulin. In this study, we assessed alterations in the IR-A and IR-B isoform ratio and associated changes in cell proliferation and migration of PCa cell lines following exposure to altered concentrations of glucose and treatment with IGF-II and insulin. We observed that where IR-B predominated insulin had a greater effect on migration than IGF-II and IGF-II was more effective when IR-A was the main isoform. With regard to proliferation IGF-II was more effective than insulin regardless of which isoform was dominant. We assessed the abundance of the IR isoforms both in vivo and in vitro and observed that the majority of the tissue samples and cell lines expressed more IR-A than IR-B. Alterations in the isoforms in response to changes in their hormonal milieu could have a profound impact on how malignant cells behave and play a role in promoting carcinogenesis. A greater understanding of the mechanisms underlying changes in alternative splicing of the IR may provide additional targets for future cancer therapies.

Insulin receptor isoforms: an integrated view focused on gestational diabetes mellitus

The human insulin receptor (IR) exists in two isoforms that differ by the absence (IR-A) or the presence (IR-B) of a 12-amino acid segment encoded by exon 11. Both isoforms are functionally distinct regarding their binding affinities and intracellular signalling. However, the underlying mechanisms related to their cellular functions in several tissues are only partially understood. In this review, we summarize the current knowledge in this field regarding the alternative splicing of IR isoform, tissue-specific distribution and signalling both in physiology and disease, with an emphasis on the human placenta in gestational diabetes mellitus (GDM). Furthermore, we discuss the clinical relevance of IR isoforms highlighted by findings that show altered insulin signalling due to differential IR-A and IR-B expression in human placental endothelium in GDM pregnancies. Future research and clinical studies focused on the role of IR isoform signalling might provide novel therapeutic targets for treating GDM to improve the adverse maternal and neonatal outcomes.

Metformin effects on biochemical recurrence and metabolic signaling in the prostate

BACKGROUND

Metformin has received considerable attention as a potential anti-cancer agent. Animal and in-vitro prostate cancer (PCa) models have demonstrated decreased tumor growth with metformin, however the precise mechanisms are unknown. We examine the effects of metformin on PCa biochemical recurrence (BCR) in a large clinical database followed by evaluating metabolic signaling changes in a cohort of men undergoing prostate needle biopsy (PNB).

METHODS

Men treated for localized PCa were identified in a comprehensive clinical database between 2001 and 2010. Cox regression was performed to determine association with BCR relative to metformin use. We next identified a separate case-control cohort of men undergoing prostate needle biopsy (PNB) stratified by metformin use. Differences in mean IHC scores were compared with linear regression for phosphorylated IR, IGF-IR, AKT, and AMPK.

RESULTS

One thousand seven hundred and thirty four men were evaluated for BCR with mean follow up of 41 months (range 1-121 months). "Ever" metformin use was not associated with BCR (HR 1.12, 0.77-1.65), however men reporting both pre/post-treatment metformin use had a 45% reduction in BCR (HR = 0.55 (0.31-0.96)). For the tissue-based study, 48 metformin users and 42 controls underwent PNB. Significantly greater staining in phosphorylated nuclear (p-IR, p-AKT) and cytoplasmic (p-IR, p-IGF-1R) insulin signaling proteins were seen in patients with PCa detected compared to those with negative PNB (P-values all <0.006). When stratified by metformin use, IGF-1R remained significantly elevated (P = 0.01) in men with PCa detected whereas p-AMPK (P = 0.05) was elevated only in those without PCa.

CONCLUSION

Metformin use is associated with reduced BCR after treatment of localized PCa when considering pre-diagnostic and cumulative dosing. In men with cancer detected on PNB, insulin signaling markers were significantly elevated compared to negative PNB patients. The finding of IGF-1R elevation in positive PNBs versus p-AMPK elevation in negative PNBs suggests altered metabolic pathway activation precipitated by metformin use.

Obesity and intestinal epithelial deletion of the insulin receptor, but not the IGF 1 receptor, affect radiation-induced apoptosis in colon

Current views suggest that apoptosis eliminates genetically damaged cells that may otherwise form tumors. Prior human studies link elevated insulin and reduced apoptosis to risk of colorectal adenomas. We hypothesized that hyperinsulinemia associated with obesity would lead to reduced colon epithelial cell (CEC) apoptosis after radiation and that this effect would be altered by deletion of the insulin-like growth factor (IGF) 1 receptor (IGF1R) or the insulin receptor (IR). Mice with villin-Cre-mediated IGF1R or IR deletion in CECs and floxed littermates were fed a high-fat diet to induce obesity and hyperinsulinemia or control low-fat chow. Mice were exposed to 5-Gy abdominal radiation to induce DNA damage and euthanized 4 h later for evaluation of apoptosis by localization of cleaved caspase-3. Obese mice exhibited decreased apoptosis of genetically damaged CECs. IGF1R deletion did not affect CEC apoptosis in lean or obese animals. In contrast, IR loss increased CEC apoptosis in both diet groups but did not prevent antiapoptotic effects of obesity. Levels of p53 protein were significantly reduced in CECs of obese mice with intact IR but increased in both lean and obese mice without IR. Levels of mRNAs encoding proapoptotic Perp and the cell cycle inhibitor Cdkn1b/p27 were reduced in CECs of obese mice and increased in lean mice lacking IR. Together, our studies provide novel evidence for antiapoptotic roles of obesity and IR, but not IGF1R, in colonic epithelium after DNA damage. However, neither IR nor IGF1R deletion prevented a reduction in radiation-induced CEC apoptosis during obesity and hyperinsulinemia.

Understanding the Key to Targeting the IGF Axis in Cancer: A Biomarker Assessment

Type 1 insulin like growth factor receptor (IGF-1R) targeted therapies showed compelling pre-clinical evidence; however, to date, this has failed to translate into patient benefit in Phase 2/3 trials in unselected patients. This was further complicated by the toxicity, including hyperglycemia, which largely results from the overlap between IGF and insulin signaling systems and associated feedback mechanisms. This has halted the clinical development of inhibitors targeting IGF signaling, which has limited the availability of biopsy samples for correlative studies to understand biomarkers of response. Indeed, a major factor contributing to lack of clinical benefit of IGF targeting agents has been difficulty in identifying patients with tumors driven by IGF signaling due to the lack of predictive biomarkers. In this review, we will describe the IGF system, rationale for targeting IGF signaling, the potential liabilities of targeting strategies, and potential biomarkers that may improve success.

Epithelial Plasticity in Cancer: Unmasking a MicroRNA Network for TGF-β-, Notch-, and Wnt-Mediated EMT

Epithelial-to-mesenchymal transition (EMT) is a reversible process by which cancer cells can switch from a sessile epithelial phenotype to an invasive mesenchymal state. EMT enables tumor cells to become invasive, intravasate, survive in the circulation, extravasate, and colonize distant sites. Paracrine heterotypic stroma-derived signals as well as paracrine homotypic or autocrine signals can mediate oncogenic EMT and contribute to the acquisition of stem/progenitor cell properties, expansion of cancer stem cells, development of therapy resistance, and often lethal metastatic disease. EMT is regulated by a variety of stimuli that trigger specific intracellular signalling pathways. Altered microRNA (miR) expression and perturbed signalling pathways have been associated with epithelial plasticity, including oncogenic EMT. In this review we analyse and describe the interaction between experimentally validated miRs and their target genes in TGF-β, Notch, and Wnt signalling pathways. Interestingly, in this process, we identified a “signature” of 30 experimentally validated miRs and a cluster of validated target genes that seem to mediate the cross talk between TGF-β, Notch, and Wnt signalling networks during EMT and reinforce their connection to the regulation of epithelial plasticity in health and disease.

Oncogenic functions of IGF1R and INSR in prostate cancer include enhanced tumor growth, cell migration and angiogenesis

We scrutinized the effect of insulin receptor (INSR) in addition to IGF1R in PCa using in vitro and in vivo models. In-vitro overexpression of IGF1R and INSRA, but not INSRB increased cell proliferation, colony formation, migration, invasion and resistance to apoptosis in prostate cancer cells (DU145, LNCaP, PC3). Opposite effects were induced by downregulation of IGF1R and total INSR, but not INSRB. In contrast to tumor cells, non-cancerous epithelial cells of the prostate (EP156T, RWPE-1) were inhibited on overexpression and stimulated by knockdown of receptors. In-vivo analyses using the chicken allantoic membrane assay confirmed the tumorigenic effects of IGF1R and INSR. Apart of promoting tumor growth, IGF1R and INSR overexpression also enhanced angiogenesis indicated by higher vessel density and increased number of desmin-immunoreactive pericytes. Our study underscores the oncogenic impact of IGF1R including significant effects on tumor growth, cell migration, sensitivity to apoptotic/chemotherapeutic agents and angiogenesis, and characterizes the INSR, in particular the isoform INSRA, as additional cancer-promoting receptor in prostate cancer. Both, the insulin-like growth factor receptor 1 and the insulin receptor exert oncogenic functions, thus proposing that both receptors need to be considered in therapeutic settings.

Taxane resistance in prostate cancer mediated by AR-independent GATA2 regulation of IGF2

GATA2 has been well-characterized as a critical pioneer transcription factor for androgen receptor (AR) in prostate cancer. In this issue of Cancer Cell, Vidal and colleagues identify increased GATA2 and its AR-independent transactivation of IGF2 as a mechanism that can mediate taxane resistance through activation of IGF1/insulin receptor signaling.

Transcriptome-wide landscape of pre-mRNA alternative splicing associated with metastatic colonization

Metastatic colonization is an ominous feature of cancer progression. Recent studies have established the importance of pre-mRNA alternative splicing (AS) in cancer biology. However, little is known about the transcriptome-wide landscape of AS associated with metastatic colonization. Both in vitro and in vivo models of metastatic colonization were utilized to study AS regulation associated with cancer metastasis. Transcriptome profiling of prostate cancer cells and derivatives crossing in vitro or in vivo barriers of metastasis revealed splicing factors with significant gene expression changes associated with metastatic colonization. These include splicing factors known to be differentially regulated in epithelial-mesenchymal transition (ESRP1, ESRP2, and RBFOX2), a cellular process critical for cancer metastasis, as well as novel findings (NOVA1 and MBNL3). Finally, RNA-seq indicated a large network of AS events regulated by multiple splicing factors with altered gene expression or protein activity. These AS events are enriched for pathways important for cell motility and signaling, and affect key regulators of the invasive phenotype such as CD44 and GRHL1.

IMPLICATIONS

Transcriptome-wide remodeling of AS is an integral regulatory process underlying metastatic colonization, and AS events affect the metastatic behavior of cancer cells.

Activation of mTOR: a culprit of Alzheimer's disease?

Alzheimer's disease (AD) is characterized by cognitive impairment in clinical presentation, and by β-amyloid (Aβ) production and the hyper-phosphorylation of tau in basic research. More highlights demonstrate that the activation of the mammalian target of rapamycin (mTOR) enhances Aβ generation and deposition by modulating amyloid precursor protein (APP) metabolism and upregulating β- and γ-secretases. mTOR, an inhibitor of autophagy, decreases Aβ clearance by scissoring autophagy function. mTOR regulates Aβ generation or Aβ clearance by regulating several key signaling pathways, including phosphoinositide 3-kinase (PI3-K)/protein kinase B (Akt), glycogen synthase kinase 3 [GSK-3], AMP-activated protein kinase (AMPK), and insulin/insulin-like growth factor 1 (IGF-1). The activation of mTOR is also a contributor to aberrant hyperphosphorylated tau. Rapamycin, the inhibitor of mTOR, may mitigate cognitive impairment and inhibit the pathologies associated with amyloid plaques and neurofibrillary tangles by promoting autophagy. Furthermore, the upstream and downstream components of mTOR signaling are involved in the pathogenesis and progression of AD. Hence, inhibiting the activation of mTOR may be an important therapeutic target for AD.

Antihyperglycaemic therapies and cancer risk

AIMS

This review is aimed at highlighting the potential mitogenic/tumour growth-promoting or antimitogenic/tumour growth-inhibiting effects of the main antihyperglycaemic drug classes.

METHODS

We review and discuss the most current studies evaluating the association between antidiabetic medications used in clinical practice and malignancies as described so far.

RESULTS

Metformin seems to be the only antidiabetic drug to exert protective effects both on monotherapy and also when combined with other oral antidiabetic drugs or insulins in several site-specific cancers. In contrast, several other drug classes may increase cancer risk. Some reason for concern remains regarding sulphonylureas and also the incretin-based therapies regarding pancreas and thyroid cancers and the sodium glucose cotransporter-2 inhibitors as well as pioglitazone regarding bladder cancer. The majority of meta-analyses suggest that there is no evidence for a causal relationship between insulin glargine and elevated cancer risk, although the studies have been controversially discussed. For α-glucosidase inhibitors and glinides, neutral or only few data upon cancer risk exist.

CONCLUSION

Although the molecular mechanisms are not fully understood, a potential risk of mitogenicity and tumour growth promotion cannot be excluded in case of several antidiabetic drug classes. However, more large-scale, randomized, well-designed clinical studies with especially long follow-up time periods are needed to get reliable answers to these safety issues.

The tyrphostin NT157 suppresses insulin receptor substrates and augments therapeutic response of prostate cancer

Insulin-like growth factor (IGF) signaling is associated with castrate-resistant prostate cancer (CRPC) progression. Insulin receptor substrates 1 and 2 (IRS1/2) mediate mitogenic and antiapoptotic signaling from IGF1 receptor (IGF1R), insulin receptor, and other oncoproteins. This study demonstrates that IRS1/2 expression is increased in prostate cancer, and persists in CRPC. Furthermore, this study assesses the anticancer activity of NT157, a small molecule tyrphostin targeting IRS proteins, using androgen-responsive (LNCaP) and -independent (PC3) prostate cancer cells in vitro and in vivo. NT157 treatment resulted in dose-dependent inhibition of IGF1R activation, suppression of IRS protein expression, inhibition of IGF1-induced AKT activation, but increased ERK activation in NT157-treated cells in vitro. These effects were correlated with decreased proliferation and increasing apoptosis of LNCaP cells and increasing G2-M arrest in PC3 cells. NT157 also suppressed androgen-responsive growth, delayed CRPC progression of LNCaP xenografts, and suppressed PC3 tumor growth alone and in combination with docetaxel. This study reports the first preclinical proof-of-principle data that this novel small molecule tyrosine kinase inhibitor suppresses IRS1/2 expression, delays CRPC progression, and suppresses growth of CRPC tumors in vitro and in vivo. Demonstration that IRS expression can be increased in response to a variety of stressors that may lead to resistance or reduced effect of the therapies indicate that NT157-mediated IRS1/2 downregulation is a novel therapeutic approach for management of advanced prostate cancer.

Increased expression of IRS-1 is associated with lymph node metastasis in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a head and neck malignant tumor rare throughout most of the world but common in Southeast Asia, especially in Southern China, which is with characteristics of early cervical lymph node metastasis and high incidence rate of distant metastasis. Insulin receptor substrate 1 (IRS-1) is a signaling adapter protein that is encoded by the IRS-1 gene in humans, plays an important role in the development, progression, invasion and metastasis of tumors. The aim of the present study was to investigate the association between the expression of IRS-1 protein and clinicopathological characteristics in NPC by immunohistochemistry. The results showed that the expression level of IRS-1 was significant higher in NPC than that in the control nasopharyngeal epithelia (P = 0.042). The positive percentage of IRS-1 expression in NPC with lymph node metastasis was also significantly higher than those without lymph node metastasis (P = 0.008). Positive expression of IRS-1 was proved to be the independent predicted factor for lymph node metastasis of NPC (P = 0.025) regardless of age, gender, histological type and clinical stages by multivariate logistic regression analysis. In addition, results showed higher sensitivity and agreement rate of IRS-1 for predicting lymph node metastasis of NPC patients. Taken together, high expression of IRS-1 might be closely correlated with lymph node metastasis in NPC and positive expression of IRS-1 could be used as an independent biomarker for predicting lymph node metastasis of NPC.

IGF1R inhibition in mammary epithelia promotes canonical Wnt signaling and Wnt1-driven tumors

Triple-negative breast cancer (TNBC) is an aggressive disease subtype that, unlike other subtypes, lacks an effective targeted therapy. Inhibitors of the insulin-like growth factor receptor (IGF1R) have been considered for use in treating TNBC. Here, we provide genetic evidence that IGF1R inhibition promotes development of Wnt1-mediated murine mammary tumors that offer a model of TNBC. We found that in a double transgenic mouse model carrying activated Wnt1 and mutant Igf1r, a reduction in IGF1R signaling reduced tumor latency and promoted more aggressive phenotypes. These tumors displayed a squamous phenotype with increased expression of keratins 5/6 and β-catenin. Notably, cell lineage analyses revealed an increase in basal (CD29(hi)/CD24(+)) and luminal (CD24(+)/CD61+/CD29(lo)) progenitor cell populations, along with increased Nanog expression and decreased Elf5 expression. In these doubly transgenic mice, lung metastases developed with characteristics of the primary tumors, unlike MMTV-Wnt1 mice. Mechanistic investigations showed that pharmacologic inhibition of the IGF1R in vitro was sufficient to increase the tumorsphere-forming efficiency ofMMTV-Wnt1 tumor cells. Tumors from doubly transgenic mice also exhibited an increase in the expression ratio of the IGF-II-sensitive, A isoform of the insulin receptor versus the IR-B isoform, which when stimulated in vitro resulted in enhanced expression of β-catenin. Overall, our results revealed that in Wnt-driven tumors, an attenuation of IGF1R signaling accelerates tumorigenesis and promotes more aggressive phenotypes with potential implications for understanding TNBC pathobiology and treatment.

Reduced insulin-like growth factor I receptor and altered insulin receptor isoform mRNAs in normal mucosa predict colorectal adenoma risk

BACKGROUND

Hyperinsulinemia resulting from obesity and insulin resistance is associated with increased risk of many cancers, but the biology underlying this risk is unclear. We hypothesized that increased mRNA levels of the insulin-like growth factor I receptor (IGFIR) versus the insulin receptor (IR) or elevated ratio of IR-A:IR-B isoforms in normal rectal mucosa would predict adenoma risk, particularly in individuals with high body mass index (BMI) or plasma insulin.

METHODS

Biopsies from normal rectal mucosa were obtained from consenting patients undergoing routine colonoscopy at University of North Carolina Hospitals (Chapel Hill, NC). Subjects with colorectal adenomas were classified as cases (n = 100) and were matched to adenoma-free controls (n = 98) based on age, sex, and BMI. IGFIR and IR mRNA levels were assessed by qRT-PCR, and IR-A:IR-B mRNA ratios by standard PCR. Plasma insulin and crypt apoptosis were measured by ELISA and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), respectively. Logistic regression models examined relationships between receptor mRNAs, BMI, plasma insulin, and adenoma risk.

RESULTS

Unexpectedly, cases were significantly more likely to have lower IGFIR mRNA levels than controls. No overall differences in total IR mRNA or IR-A:IR-B ratios were observed between cases and controls. Interestingly, in patients with high plasma insulin, increased IR-A:IR-B ratio was associated with increased likelihood of having adenomas.

CONCLUSIONS

Our work shows novel findings that reduced IGFIR mRNA and, during high plasma insulin, increased IR-A:IR-B ratios in normal rectal mucosa are associated with colorectal adenoma risk.

IMPACT

Our work provides evidence supporting a link between IGFIR and IR isoform expression levels and colorectal adenoma risk.

Obesity and cancer pathogenesis

Overweight and obesity have reached pandemic levels on a worldwide basis and are associated with increased risk and worse prognosis for many but not all malignancies. Pathophysiologic processes that affect this association are reviewed, with a focus on the relationship between type 2 diabetes mellitus and cancer, lessons learned from the use of murine models to study the association, the impact of obesity on pancreatic cancer, the effects of dietary fats and cholesterol on cancer promotion, and the mechanisms by which the intestinal microbiome affects obesity and cancer.

Insulin receptor (IR) and insulin-like growth factor receptor 1 (IGF-1R) signaling systems: novel treatment strategies for cancer

Insulin and insulin-like growth factor (IGF) signaling system, commonly known for fine-tuning numerous biological processes, has lately made its mark as a much sought-after therapeutic targets for diabetes and cancer. These receptors make an attractive anticancer target owing to their overexpression in variety of cancer especially in prostate and breast cancer. Inhibitors of IGF signaling were subjected to clinical cancer trials with the main objective to confirm the effectiveness of these receptors as a therapeutic target. However, the results that these trials produced proved to be disappointing as the role played by the cross talk between IGF and insulin receptor (IR) signaling pathways at the receptor level or at downstream signaling level became more lucid. Therapeutic strategy for IGF-1R and IR inhibition mainly encompasses three main approaches namely receptor blockade with monoclonal antibodies, tyrosine kinase inhibition (ATP antagonist and non-ATP antagonist), and ligand neutralization via monoclonal antibodies targeted to ligand or recombinant IGF-binding proteins. Other drug-discovery approaches are employed to target IGF-1R, and IR includes antisense oligonucleotides and recombinant IGF-binding proteins. However, therapies with monoclonal antibodies and tyrosine kinase inhibition targeting the IGF-1R are not evidenced to be satisfactory as expected. Factors that are duly held responsible for the unsuccessfulness of these therapies include (a) the existence of the IR isoform A overexpressed on a variety of cancers, enhancing the mitogenic signals to the nucleus leading to the endorsement of cell growth, (b) IGF-1R and IR that form hybrid receptors sensitive to the stimulation of all three IGF axis ligands, and (c) IGF-1R and IR that also have the potential to form hybrid receptors with other tyrosine kinase to potentiate the cellular transformation, tumorigenesis, and tumor vascularization. This mini review is a concerted effort to explore and fathom the well-recognized roles of the IRA signaling system in human cancer phenotype and the main strategies that have been so far evaluated to target the IR and IGF-1R.

Insulin receptor isoform switching in intestinal stem cells, progenitors, differentiated lineages and tumors: evidence that IR-B limits proliferation

Despite evidence for the impact of insulin on intestinal epithelial physiology and pathophysiology, the expression patterns, roles, and regulation of insulin receptor (IR) and IR isoforms in the intestinal epithelium are not well characterized. IR-A is thought to mediate the proliferative effects of insulin or insulin growth factors (IGFs) in fetal or cancer cells. IR-B is considered to be the metabolic receptor for insulin in specialized tissues. This study used a novel Sox9-EGFP reporter mouse that permits isolation of intestinal epithelial stem cells (IESCs), progenitors, enteroendocrine cells and differentiated lineages, the Apc(Min/+) mouse model of precancerous adenoma and normal human intestinal and colorectal cancer (CRC) cell lines. We tested the hypothesis that there is differential expression of IR-A or IR-B in stem and tumor cells versus differentiated intestinal epithelial cells (IECs) and that IR-B impacts cell proliferation. Our findings provide evidence that IR-B expression is significantly lower in highly proliferative IESCs and progenitor cells versus post-mitotic, differentiated IECs and in subconfluent and undifferentiated versus differentiated Caco-2 cells. IR-B is also reduced in Apc(Min/+) tumors and highly tumorigenic CRC cells. These differences in IR-B were accompanied by altered levels of mRNAs encoding muscleblind-like 2 (MBNL2), a known regulator of IR alternative splicing. Forced IR-B expression in subconfluent and undifferentiated Caco-2 cells reduced proliferation and increased biomarkers of differentiation. Our findings indicate that the impact of insulin on different cell types in the intestinal epithelium might differ depending on relative IR-B IR-A expression levels and provide new evidence for the roles of IR-B to limit proliferation of CRC cells.

New players for advanced prostate cancer and the rationalisation of insulin-sensitising medication

Obesity and type 2 diabetes are recognised risk factors for the development of some cancers and, increasingly, predict more aggressive disease, treatment failure, and cancer-specific mortality. Many factors may contribute to this clinical observation. Hyperinsulinaemia, dyslipidaemia, hypoxia, ER stress, and inflammation associated with expanded adipose tissue are thought to be among the main culprits driving malignant growth and cancer advancement. This observation has led to the proposal of the potential utility of "old players" for the treatment of type 2 diabetes and metabolic syndrome as new cancer adjuvant therapeutics. Androgen-regulated pathways drive proliferation, differentiation, and survival of benign and malignant prostate tissue. Androgen deprivation therapy (ADT) exploits this dependence to systemically treat advanced prostate cancer resulting in anticancer response and improvement of cancer symptoms. However, the initial therapeutic response from ADT eventually progresses to castrate resistant prostate cancer (CRPC) which is currently incurable. ADT rapidly induces hyperinsulinaemia which is associated with more rapid treatment failure. We discuss current observations of cancer in the context of obesity, diabetes, and insulin-lowering medication. We provide an update on current treatments for advanced prostate cancer and discuss whether metabolic dysfunction, developed during ADT, provides a unique therapeutic window for rapid translation of insulin-sensitising medication as combination therapy with antiandrogen targeting agents for the management of advanced prostate cancer.