Targeting the insulin growth factor and the vascular endothelial growth factor pathways in ovarian cancer

Enhancing Immunotherapy in Ovarian Cancer: The Emerging Role of Metformin and Statins

Ovarian cancer metastization is accompanied by the development of malignant ascites, which are associated with poor prognosis. The acellular fraction of this ascitic fluid contains tumor-promoting soluble factors, bioactive lipids, cytokines, and extracellular vesicles, all of which communicate with the tumor cells within this peritoneal fluid. Metabolomic profiling of ovarian cancer ascites has revealed significant differences in the pathways of fatty acids, cholesterol, glucose, and insulin. The proteins involved in these pathways promote tumor growth, resistance to chemotherapy, and immune evasion. Unveiling the key role of this liquid tumor microenvironment is crucial for discovering more efficient treatment options. This review focuses on the cholesterol and insulin pathways in ovarian cancer, identifying statins and metformin as viable treatment options when combined with standard chemotherapy. These findings are supported by clinical trials showing improved overall survival with these combinations. Additionally, statins and metformin are associated with the reversal of T-cell exhaustion, positioning these drugs as potential combinatory strategies to improve immunotherapy outcomes in ovarian cancer patients.

New Strategy for Promoting Vascularization in Tumor Spheroids in a Microfluidic Assay

Previous studies have developed vascularized tumor spheroid models to demonstrate the impact of intravascular flow on tumor progression and treatment. However, these models have not been widely adopted so the vascularization of tumor spheroids in vitro is generally lower than vascularized tumor tissues in vivo. To improve the tumor vascularization level, a new strategy is introduced to form tumor spheroids by adding fibroblasts (FBs) sequentially to a pre-formed tumor spheroid and demonstrate this method with tumor cell lines from kidney, lung, and ovary cancer. Tumor spheroids made with the new strategy have higher FB densities on the periphery of the tumor spheroid, which tend to enhance vascularization. The vessels close to the tumor spheroid made with this new strategy are more perfusable than the ones made with other methods. Finally, chimeric antigen receptor (CAR) T cells are perfused under continuous flow into vascularized tumor spheroids to demonstrate immunotherapy evaluation using vascularized tumor-on-a-chip model. This new strategy for establishing tumor spheroids leads to increased vascularization in vitro, allowing for the examination of immune, endothelial, stromal, and tumor cell responses under static or flow conditions.

Efficacy evaluation of multi-immunotherapy in ovarian cancer: From bench to bed

Ovarian cancer, one of the most common gynecological malignancies, is characterized by high mortality and poor prognosis. Cytoreductive surgery and chemotherapy remain the mainstay of ovarian cancer treatment, and most women experience recurrence after standard care therapies. There is compelling evidence that ovarian cancer is an immunogenic tumor. For example, the accumulation of tumor-infiltrating lymphocytes is associated with increased survival, while increases in immunosuppressive regulatory T cells are correlated with poor clinical outcomes. Therefore, immunotherapies targeting components of the tumor microenvironment have been gradually integrated into the existing treatment options, including immune checkpoint blockade, adoptive cell therapy, and cancer vaccines. Immunotherapies have changed guidelines for maintenance treatment and established a new paradigm in ovarian cancer treatment. Despite single immunotherapies targeting DNA repair mechanisms, immune checkpoints, and angiogenesis bringing inspiring efficacy, only a subset of patients can benefit much from it. Thus, the multi-immunotherapy investigation remains an active area for ovarian cancer treatment. The current review provides an overview of various clinically oriented forms of multi-immunotherapy and explores potentially effective combinational therapies for ovarian cancer.

Effects of Intravitreal Aflibercept on the Systemic Insulin-like Growth Factor-I and Vascular Endothelial Growth Factor-A in Patients with Diabetic Retinopathy and Age-Related Macular Degeneration

Purpose

To analyze the effect of intravitreal aflibercept injections on systemic levels of insulin-like growth factor-1 and vascular endothelial growth factor-A in patients with diabetic retinopathy and age-related macular degeneration.

Methods

Vascular endothelial growth factor-A and insulin-like growth factor-1 levels were determined before and one week and four weeks after intravitreal injection of aflibercept (2.0 mg/50 μl) for 19 patients with age-related macular degeneration (mean age, 76 ± 11 years) and 18 patients with diabetic retinopathy (mean age, 64 ± 14 years). Twenty-two healthy individuals were enrolled as controls.

Results

A significant decline in systemic vascular endothelial growth factor-A level, from 43 (30–57) pg/ml at baseline to 8 (8–8) pg/ml (p < 0.001) at week one and 17 (8–25) pg/ml (p=0.0054) at week four, was observed in the age-related macular degeneration group. In the diabetic retinopathy group, vascular endothelial growth factor-A levels declined from 53 (35–117) pg/ml to 2 (1–5) pg/ml (p < 0.0001) one week after injection and 16 (13–22) pg/ml four weeks after injection (p=0.0327). At baseline, systemic insulin-like growth factor-1 concentration was higher in the diabetic retinopathy group (57 [37–99] pg/ml) than in the age-related macular degeneration group (35 [24–51] pg/ml) (p=0.0056). A subgroup analysis showed that patients in the proliferative diabetic retinopathy subgroup had significantly higher systemic insulin-like growth factor-1 concentrations (71 [44.7–243] pg/ml) than those in the nonproliferative diabetic retinopathy subgroup (43 [29–66] pg/ml) (p=0.0048).

Conclusions

The difference between the baseline systemic insulin-like growth factor-1 levels of the age-related macular degeneration and diabetic retinopathy groups and the higher insulin-like growth factor-1 levels in the proliferative diabetic retinopathy subgroup one week after aflibercept therapy suggest that insulin-like growth factor-1 may play a role in the pathomechanism of diabetic retinopathy.

Platinum-based chemotherapy and bevacizumab instigate the destruction of human ovarian cancers via different signaling pathways

The standard chemotherapy regimens of ovarian cancer are platinum-based chemotherapy (carboplatin and paclitaxel) and bevacizumab (BEV). However, the effects of BEV alone or combined with carboplatin and paclitaxel on mitochondrial dynamics, mitochondrial function, mitophagy, apoptosis, inflammation and vascular endothelial growth factor (VEGF) in human ovarian cancer mitochondria and cells have not yet been investigated. Therefore, we aimed to test the hypothesis that 1) platinum-based chemotherapy and BEV equally damage isolated mitochondria from human ovarian cancers, and ovarian cancer cells through inducing mitochondrial dynamics dysregulation, mitochondrial dysfunction, increased mitophagy and apoptosis, as well as altered inflammation and VEGF; and 2) combined therapies exert greater damage than monotherapy. Each isolated human ovarian cancer mitochondria (n = 16) or CaOV3 cells (n = 6) were treated with either platinum-based chemotherapy (carboplatin 10 μM and paclitaxel 5 μM), BEV (2 mg/mL) or combined platinum-based chemotherapy and BEV for 60 min or 24 h, respectively. Following the treatment, mitochondrial dynamics, mitochondrial function, mitophagy, apoptosis, cytotoxicity, inflammation and VEGF were determined. Platinum-based chemotherapy caused ovarian cancer mitochondria and cell damage through mitochondrial dysfunction, increased cell death with impairment of membrane integrity, and enhanced VEGF reduction, while BEV did not. BEV caused deterioration of ovarian cancer mitochondria and cells through mitochondrial-dependent apoptosis, but it had no effect on cell viability. Interestingly, combined platinum-based chemotherapy and BEV treatments had no addictive effects on all parameters except mitochondrial maximal respiration, when compared to monotherapy. Collectively, these findings suggest that platinum-based chemotherapy and BEV caused human ovarian cancer mitochondrial and cell damage through different mechanisms.

Pyrrole derivatives as potential anti-cancer therapeutics: synthesis, mechanisms of action, safety

Pyrrole derivatives (PDs) chloro-1-(4-chlorobenzyl)-4-((3-(trifluoromethyl)phenyl)amino)-1H-pyrrole-2,5-dione (MI-1) and 5-amino-4-(1,3-benzothyazol-2-yn)-1-(3-methoxyphenyl)-1,2-dihydro-3H-pyrrole-3-one (D1) were synthesised as inhibitors of several protein kinases including EGFR and VEGFR. The aim of the study was to reveal the exact mechanisms of PDs' action EGFR and VEGFR are involved in. We observed, that both PDs could bind with EGFR and VEGFR and form stable complexes. PDs entered into electrostatic interactions with polar groups of phospholipid heads in cell membrane, and the power of interaction depended on the nature of PD radical substituents (greater for MI-1 and smaller for D1). Partial intercalation of MI-1 into the membrane hydrophobic zone also occurred. PDs concentrations induced apoptosis in malignant cells but normal ones had different sensitivity to those. MI-1 and D1 acted like antioxidants in inflamed colonic tissue, as evidenced by reduce of lipid and protein peroxidation products (by 43-67%) and increase of superoxide dismutase activity (by 40 and 58%) with restoring these values to control ones. MI-1 restored reduced haemoglobin and normalised elevated platelets and monocytes in settings of colorectal cancer, whereas D1 normalised only platelets. Thus, MI-1 and D1 could be used as competitive inhibitors of EGFR and VEGFR and antioxidants, which might contribute to realisation of their anti-inflammatory, proapoptotic and antitumor activity.

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.

Aminopeptidase N (CD13) targeted MR and NIRF dual-modal imaging of ovarian tumor xenograft

The development of tumor-specific imaging nanoprobes with the potential to improve the accuracy of cancer diagnosis has become an area of intense research. Aminopeptidase N (CD13) predominantly expresses on the surface of ovarian tumor cells and can be specifically recognized by Asn-Gly-Arg (NGR) peptide. The applicability of CD13 as a target for specific ovarian tumor imaging, however, remains unexploited so far. In this study, Cy5.5-labeled, NGR-conjugated iron oxide nanoparticles (Cy5.5-NGR-Fe₃O₄ NPs) were prepared as an ovarian tumor specific bimodal imaging nanoprobe. It is demonstrated that the conjugation of NGR targeting moiety leads to a higher cellular uptake toward ES-2 cells, the human ovarian carcinoma cells that highly express CD13. Moreover, magnetic resonance imaging of ovarian tumor xenograft reveals that the Fe₃O₄-Cy5.5-NGR NPs results in a significant T₂* signal reduction in the tumor. Meanwhile, near infrared fluorescence imaging indicates a higher accumulation of Fe₃O₄-Cy5.5-NGR NPs in the tumor xenograft. Therefore, CD13 could be applied as a novel and efficient target for constructing ovarian tumor specific nanoprobes with improved accuracy for ovarian tumor diagnosis.

Phase 2 study evaluating intermittent and continuous linsitinib and weekly paclitaxel in patients with recurrent platinum resistant ovarian epithelial cancer

BACKGROUND

Linsitinib, an oral, dual inhibitor of insulin-like growth factor-1 receptor and insulin receptor, in combination with weekly paclitaxel, may improve clinical outcomes compared with paclitaxel alone in patients with refractory or platinum-resistant ovarian cancer.

PATIENTS AND METHODS

This open-label phase 1/2 clinical trial (NCT00889382) randomized patients with refractory or platinum-resistant ovarian cancer (1:1:1) to receive either oral intermittent linsitinib (600mg once daily on Days 1-3 per week) combined with paclitaxel (80mg/m² on Days 1, 8, and 15; Arm A) or continuous linsitinib (150mg twice daily) in combination with paclitaxel (Arm B), or paclitaxel alone (Arm C). Primary endpoint was progression-free survival (PFS); secondary endpoints included overall survival (OS), overall response rate (ORR), disease control rate (DCR), and safety/tolerability.

RESULTS

A total of 152 women were randomized to treatment (n=51 Arm A; n=51 Arm B, n=50 Arm C). In combination with paclitaxel, neither intermittent linsitinib (median PFS 2.8months; 95% confidence interval [CI]:2.5-4.4) nor continuous linsitinib (median PFS 4.2months; 95% CI:2.8-5.1) improved PFS over weekly paclitaxel alone (median PFS 5.6months; 95% CI:3.2-6.9). No improvement in ORR, DCR, or OS in either linsitinib dosing schedule was observed compared with paclitaxel alone. Adverse event (AE) rates, including all-grade and grade 3/4 treatment-related AEs, and treatment-related AEs leading to discontinuation, were higher among patients receiving intermittent linsitinib compared with the other treatment arms.

CONCLUSION

Addition of intermittent or continuous linsitinib with paclitaxel did not improve outcomes in patients with platinum-resistant/refractory ovarian cancer compared with paclitaxel alone.

The Role of the Insulin-Like Growth Factor 1 Pathway in Immune Tumor Microenvironment and Its Clinical Ramifications in Gynecologic Malignancies

Treatment of patients with gynecologic malignancies diagnosed at advanced stages remains a therapeutic challenge. Survival rates of these patients remain significantly low, despite surgery and chemotherapy. Advances in understanding the role of the immune system in the pathogenesis of cancer have led to the rapid evolution of immunotherapeutic approaches. Immunotherapeutic strategies, including targeting specific immune checkpoints, as well as dendritic cell (DC) immunotherapy are being investigated in several malignancies, including gynecological cancers. Another important approach in cancer therapy is to inhibit molecular pathways that are crucial for tumor growth and maintenance, such as the insulin-like growth factor-1 (IGF1) pathway. The IGF axis has been shown to play a significant role in carcinogenesis of several types of tissue, including ovarian cancer. Preclinical studies reported significant anti-proliferative activity of IGF1 receptor (IGF1R) inhibitors in gynecologic malignancies. However, recent clinical studies have shown variable response rates with advanced solid tumors. This study provides an overview on current immunotherapy strategies and on IGF-targeted therapy for gynecologic malignancies. We focus on the involvement of IGF1R signaling in DCs and present our preliminary results which imply that the IGF axis contributes to an immunosuppressive tumor microenvironment (TME). For the long term, we believe that restoring the TME function by IGF1R targeting in combination with immunotherapy can serve as a new clinical approach for gynecological cancers.

Gene expression levels of the insulin-like growth factor family in patients with AMD before and after ranibizumab intravitreal injections

Purpose

The present study focused on the assessment of the mRNA levels of the insulin-like growth factor (IGF) family in patients with the exudative form of age-related macular degeneration (AMD) before and after ranibizumab intravitreal injections.

Patients and methods

An analysis of the expression profile of the IGF family of genes in patients with AMD was carried out using the oligonucleotide microarray and quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) methods.

Results

In the peripheral blood mononuclear cells (PBMCs) obtained from AMD group receiving ranibizumab compared to the peripheral blood mononuclear cells from AMD group before ranibizumab treatment using oligonucleotide microarray technique, six statistically significant differentially expressed transcripts related to the IGF family were detected (unpaired t-test, p<0.05, fold change >1.5). Moreover, analysis using the real-time RT-qPCR technique revealed statistically significant differences in the IGF2 and IGF2R mRNA levels (Mann–Whitney U test, p<0.05) between the two groups that were studied. Statistical analyses of both oligonucleotide microarray and real-time RT-qPCR results demonstrated a significant decreased expression only for IGF2 mRNA.

Conclusion

Our results revealed a changed expression of IGF2 mRNA after ranibizumab treatment.

IGF system targeted therapy: Therapeutic opportunities for ovarian cancer

The insulin-like growth factor (IGF) system comprises multiple growth factor receptors, including insulin-like growth factor 1 receptor (IGF-1R), insulin receptor (IR) -A and -B. These receptors are activated upon binding to their respective growth factor ligands, IGF-I, IGF-II and insulin, and play an important role in development, maintenance, progression, survival and chemotherapeutic response of ovarian cancer. In many pre-clinical studies anti-IGF-1R/IR targeted strategies proved effective in reducing growth of ovarian cancer models. In addition, anti-IGF-1R targeted strategies potentiated the efficacy of platinum based chemotherapy. Despite the vast amount of encouraging and promising pre-clinical data, anti-IGF-1R/IR targeted strategies lacked efficacy in the clinic. The question is whether targeting the IGF-1R/IR signaling pathway still holds therapeutic potential. In this review we address the complexity of the IGF-1R/IR signaling pathway, including receptor heterodimerization within and outside the IGF system and downstream signaling. Further, we discuss the implications of this complexity on current targeted strategies and indicate therapeutic opportunities for successful targeting of the IGF-1R/IR signaling pathway in ovarian cancer. Multiple-targeted approaches circumventing bidirectional receptor tyrosine kinase (RTK) compensation and prevention of system rewiring are expected to have more therapeutic potential.

The IGF1R/INSR Inhibitor BI 885578 Selectively Inhibits Growth of IGF2-Overexpressing Colorectal Cancer Tumors and Potentiates the Efficacy of Anti-VEGF Therapy

Clinical studies of pharmacologic agents targeting the insulin-like growth factor (IGF) pathway in unselected cancer patients have so far demonstrated modest efficacy outcomes, with objective responses being rare. As such, the identification of selection biomarkers for enrichment of potential responders represents a high priority for future trials of these agents. Several reports have described high IGF2 expression in a subset of colorectal cancers, with focal IGF2 amplification being responsible for some of these cases. We defined a novel cut-off value for IGF2 overexpression based on differential expression between colorectal tumors and normal tissue samples. Analysis of two independent colorectal cancer datasets revealed IGF2 to be overexpressed at a frequency of 13% to 22%. An in vitro screen of 34 colorectal cancer cell lines revealed IGF2 expression to significantly correlate with sensitivity to the IGF1R/INSR inhibitor BI 885578. Furthermore, autocrine IGF2 constitutively activated IGF1R and Akt phosphorylation, which was inhibited by BI 885578 treatment. BI 885578 significantly delayed the growth of IGF2-high colorectal cancer xenograft tumors in mice, while combination with a VEGF-A antibody increased efficacy and induced tumor regression. Besides colorectal cancer, IGF2 overexpression was detected in more than 10% of bladder carcinoma, hepatocellular carcinoma and non-small cell lung cancer patient samples. Meanwhile, IGF2-high non-colorectal cancer cells lines displayed constitutive IGF1R phosphorylation and were sensitive to BI 885578. Our findings suggest that IGF2 may represent an attractive patient selection biomarker for IGF pathway inhibitors and that combination with VEGF-targeting agents may further improve clinical outcomes. Mol Cancer Ther; 16(10); 2223-33. ©2017 AACR.

Targeting human vasohibin-2 by a neutralizing monoclonal antibody for anti-cancer treatment

There are two members of the vasohibin (VASH) family, VASH1 and VASH2. VASH1 is expressed mainly in endothelial cells to inhibit angiogenesis, whereas VASH2 is expressed mainly in cancer cells to stimulate tumor growth. The aim of the present study was to establish neutralizing monoclonal antibody (mAb) against human VASH2 and apply it as an anti‐cancer treatment. We previously raised mAb against several synthetic peptides of hVASH1, and found that one of them exhibited neutralizing activity against hVASH1. Because of the similarity in the amino acid sequences between VASH1 and VASH2, we hypothesized that they shared the bioactive center. When we mutated four amino acids within the region, the mutant VASH2 lost its pro‐angiogenic activity. Therefore, we raised mAb against a synthetic peptide overlapping the mutated amino acids of hVASH2, and isolated one clone (1760) that almost completely inhibited the stimulatory effect of hVASH2 on the migration of and tube formation by endothelial cells. When we used this clone 1760 antibody for cancer treatment, the peritoneal injection of it inhibited both tumor growth and angiogenesis in a mouse xenograft model of human cancer cells. In terms of anti‐tumor activity, 25 mg/kg of clone 1760 was equivalent to 5 mg/kg of bevacizmab. From these results, we propose the targeting of human VASH2 with neutralizing mAb as a new strategy for cancer treatment.

Nucleus accumbens-associated protein-1 promotes glycolysis and survival of hypoxic tumor cells via the HDAC4-HIF-1α axis

Nucleus accumbens-associated protein-1 (NAC1), a nuclear factor of the BTB/POZ gene family, has emerging roles in cancer. In this study, we identified the NAC1-HDAC4-HIF-1α axis as an important pathway in regulating glycolysis and hypoxic adaptation in tumor cells. We show that nuclear NAC1 binds to histone deacetylase type 4 (HDAC4), hindering phosphorylation of HDAC4 at Ser²⁴⁶ and preventing its nuclear export that leads to cytoplasmic degradation of the deacetylase. Accumulation of HDAC4 in the nuclei results in an attenuation of HIF-1α acetylation, enhancing the stabilization and transcriptional activity of HIF-1α and strengthening adaptive response of cells to hypoxia. We also show the role of NAC1 in promoting glycolysis in a mouse xenograft model, and demonstrate that knockdown of NAC1 expression can reinforce the antitumor efficacy of bevacizumab, an inhibitor of angiogenesis. Clinical implication of the NAC1-HDAC4-HIF-1α pathway is suggested by the results showing that expression levels of these proteins are significantly correlative in human tumor specimens and associated with the disease progression. This study not only reveals an important function of NAC1 in regulating glycolysis, but also identifies the NAC1-HDAC4-HIF-1α axis as a novel molecular pathway that promotes survival of hypoxic tumor cells.

Insulin-like growth factor axis targeting in cancer and tumour angiogenesis - the missing link

Numerous molecular players in the process of tumour angiogenesis have been shown to offer potential for therapeutic targeting. Initially denoted to be involved in malignant transformation and tumour progression, the insulin-like growth factor (IGF) signalling axis has been subject to therapeutic interference, albeit with limited clinical success. More recently, IGFs and their receptors have received attention for their contribution to tumour angiogenesis, which offers novel therapeutic opportunities. Here we review the contribution of this signalling axis to tumour angiogenesis, the mechanisms of resistance to therapy and the interplay with other pro-angiogenic pathways, to offer insight in the renewed interest in the application of IGF axis targeting agents in anti-cancer combination therapies.

The TGFβ pathway stimulates ovarian cancer cell proliferation by increasing IGF1R levels

In a search for new therapeutic targets for treating epithelial ovarian cancer, we analyzed the Transforming Growth Factor Beta (TGFβ) signaling pathway in these tumors. Using a TMA with patient samples we found high Smad2 phosphorylation in ovarian cancer tumoral cells, independently of tumor subtype (high-grade serous or endometrioid). To evaluate the impact of TGFβ receptor inhibition on tumoral growth, we used different models of human ovarian cancer orthotopically grown in nude mice (OVAs). Treatment with a TGFβRI&II dual inhibitor, LY2109761, caused a significant reduction in tumor size in all these models, affecting cell proliferation rate. We identified Insulin Growth Factor (IGF)1 receptor as the signal positively regulated by TGFβ implicated in ovarian tumor cell proliferation. Inhibition of IGF1R activity by treatment with a blocker antibody (IMC-A12) or with a tyrosine kinase inhibitor (linsitinib) inhibited ovarian tumoral growth in vivo. When IGF1R levels were decreased by shRNA treatment, LY2109761 lost its capacity to block tumoral ovarian cell proliferation. At the molecular level TGFβ induced mRNA IGF1R levels. Overall, our results suggest an important role for the TGFβ signaling pathway in ovarian tumor cell growth through the control of IGF1R signaling pathway. Moreover, it identifies anti-TGFβ inhibitors as being of potential use in new therapies for ovarian cancer patients as an alternative to IGF1R inhibition.

Clinical prospects of IGF-signaling system components study in ovarian cancer patients

Among various auto/paracrine growth-regulating signaling pathways an important role belongs to that of insulin-like growth factors (IGFs) and insulin. IGF-signaling system is actively involved in the regulation of both normal ovarian function and ovarian tumor growth. On the one hand, all members of this system are expressed in malignant ovarian epithelial cells, and the prognostic significance of this expression has been revealed for some of them in ovarian cancer patients in several studies. On the other hand, circulating IGFs/IGFBPs levels have not been undoubtedly associated with ovarian cancer risk or disease progression, but some of them can be regarded as supplementary serological ovarian cancer markers. An important route to the clinical application of IGF-signaling system studies in ovarian cancer is the growing possibility of using specific molecular targeted agents to suppress its growth-stimulating and other activities. However, the introduction of such agents to practical oncology has met serious problems, with the main difficulties resulting from the absence of reliable predictive molecular markers and metabolic side effects due to the tight connection between IGF-signaling and insulin-regulated processes. The prognostic and diagnostic values of various IGF system components and the current state of corresponding molecular targeted therapies development for ovarian cancer are reviewed.

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

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

Recent progress in genetics of aging, senescence and longevity: focusing on cancer-related genes

It is widely believed that aging results from the accumulation of molecular damage, including damage of DNA and mitochondria and accumulation of molecular garbage both inside and outside of the cell. Recently, this paradigm is being replaced by the “hyperfunction theory”, which postulates that aging is caused by activation of signal transduction pathways such as TOR (Target of Rapamycin). These pathways consist of different enzymes, mostly kinases, but also phosphatases, deacetylases, GTPases, and some other molecules that cause overactivation of normal cellular functions. Overactivation of these sensory signal transduction pathways can cause cellular senescence, age-related diseases, including cancer, and shorten life span. Here we review some of the numerous very recent publications on the role of signal transduction molecules in aging and age-related diseases. As was emphasized by the author of the “hyperfunction model”, many (or actually all) of them also play roles in cancer. So these “participants” in pro-aging signaling pathways are actually very well acquainted to cancer researchers. A cancer-related journal such as Oncotarget is the perfect place for publication of such experimental studies, reviews and perspectives, as it can bridge the gap between cancer and aging researchers.

The links between insulin resistance, diabetes, and cancer

The growing epidemic of obesity has resulted in a large increase in multiple related diseases. Recent evidence has strengthened the proposed synergistic relationship between obesity-related insulin resistance (IR) and/or diabetes mellitus (DM) and cancer. Within the past year, many studies have examined this relationship. Although the precise mechanisms and pathways are uncertain, it is becoming clear that hyperinsulinemia and possibly sustained hyperglycemia are important regulators of not only the development of cancer but also of treatment outcome. Further, clinical decision-making regarding the treatment of choice for DM will likely be impacted as we learn more about the non-metabolic effects of the available hyperglycemic agents. In our review, we endeavored to synthesize the recent literature and provide a concise view of the journey from macro-level clinical associations to specific mechanistic relationships being elucidated in cell lines and animal models.

The correlation of hematopoietic stem cells with cancer stem cells through the regulation of stromal cells in tumor microenvironment

Cancer stem cells are a small population of tumor cells that have many malignant features such as chemotherapy resistance, radiotherapy resistance, tumorigenicity and are responsible for tumor progression, disease recurrence and metastasis. Therefore, insight into the regulation of the biology of cancer stem cells is important to eradicate cancer. Recently, studies suggested that hematopoietic stem cells could incorporate into tumor stroma and differentiated into stromal cells and the cells derived from hematopoietic stem cells play an important role on tumor progress. Moreover, cancer cells competed with hematopoietic stem cells for occupancy of the hematopoietic stem cell niches to regulate bone metastasis and most cancer cells in bone marrow metastasis were cancer stem cells. Therefore, we hypothesize that cancer stem cells could promote hematopoietic stem cells incorporating into tumor microenvironment and resulting into transformation of hematopoietic stem cells to stromal cells, which could impact the biological behavior of cancer stem cells.

Targeting IGF-1 signaling pathways in gynecologic malignancies

INTRODUCTION

The signaling pathways of the insulin-like growth factors (IGF) have been implicated in the etiology of a number of epithelial neoplasms including prostate, breast, colon and more recently, gynecologic cancers. The insulin-like growth factor-1 receptor (IGF-1R) is expressed in most transformed cells, where it displays potent anti-apoptotic, cell-survival and potentially, transforming activities. IGF-1R expression and activation are typical hallmarks associated with tumor initiation and progression. Multiple approaches have been used to abrogate IGF-1R signaling for targeted cancer therapy including antibodies and small molecule tyrosine kinase inhibitors. These novel IGF-1R targeting agents have produced significant experimental and clinical results in many cancers and generated considerable optimism in the field of cancer therapy.

AREAS COVERED

The authors will review important research advances regarding the role of the IGF axis in cancer, particularly preclinical and clinical studies in cervical, uterine and ovarian cancers. The significance of tumor expression and circulating levels of the IGF pathway as well as targeting therapies of the IGF axis in the gynecologic cancers will be discussed.

EXPERT OPINION

Accumulating data confirm that the IGF-1R pathway has an important role in gynecologic cancers and in vivo and in vitro studies have shown a significant impact of IGF-1R targeted therapies in these malignancies, mainly ovarian and endometrial cancers. Currently, ongoing preclinical and clinical trials are evaluating the efficacy of IGF-1R targeting. A better understanding of the complex mechanisms underlying the regulation of the IGF system will improve the ability to develop effective treatment modalities for these malignancies.