IGF-I in epithelial ovarian cancer and its role in disease progression

Diabetes and ovarian cancer: risk factors, molecular mechanisms and impact on prognosis

BACKGROUND AND AIM

Diabetes mellitus has been linked to a lower rate of cancer survival and an increase in the incidence of most malignancies. Investigations showed that diabetes might affect ovarian cancer (OC) prognosis and survival. Based on the current information, this study intends to review the risk factors, molecular pathways, and impact of diabetes on OC.

METHODS

The data was derived from online databases, including Web of Science, PubMed, and Scopus. The inclusion criteria were original studies, which included the risk factors, molecular mechanisms, and impact of diabetes on OC. The effect of different antidiabetic drugs was also discussed in this manuscript. All of the clinical, in vivo, and in vitro studies were included in the present study.

RESULTS

The diagnosis of diabetes mellitus negatively affects the survival and prognosis in OC cases. The epidemiologic data shows that the risk of OC increases in patients with diabetes mellitus compared to the healthy population. Insulin-like growth factors family was raised in diabetic patients, which target several mechanisms, including targeting oxidative stress, angiogenesis, and tumor markers. Antidiabetic drugs such as metformin, sitagliptin, and rosiglitazone have a promising effect on elongation of survival and enhancement of prognosis in OC patients.

CONCLUSIONS

Diabetes mellitus is a significant risk factor for OC in women, and it negatively impacts survival and prognosis. Molecular mechanisms such as IGF family, oxidative stress, and inflammatory cytokines have been identified to explain this relationship. Antidiabetic drugs like metformin, sitagliptin, and rosiglitazone have shown promise in improving survival and prognosis of OC patients.

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.

Oversupply of Limiting Cell Resources and the Evolution of Cancer Cells: A Review

Cancer prevention is superior to cancer treatment—indeed, understanding and controlling cancer risk is a key question in the fields of applied ecology and evolutionary oncology. Ecological cancer risk models offer the dual benefit of being generalizable across cancer types, and unveiling common mechanisms underlying cancer development and spread. Understanding the biological mechanisms of cancer risk may also guide the design of interventions to prevent cancer. Ecological considerations are central to many of these mechanisms; as one example, the ecologically-based hypothesis of metabolic cancer suppression posits that restricted vascular supply of limiting resources to somatic tissues normally suppresses the evolution of somatic cells toward cancer. Here we present a critical review of published evidence relevant to this hypothesis, and we conclude that there is substantial evidence that cancer risk does increase with an abnormal excess of limiting cell resources, including both dietary macronutrients as well as certain micronutrients.

IGF1R Axis Inhibition Restores Dendritic Cell Antitumor Response in Ovarian Cancer

Epithelial ovarian cancer (EOC) is the most lethal gynecological malignancy. The insulin-like growth factor (IGF) system plays a key role in regulating growth and invasiveness in several malignancies, including ovarian cancer. IGF1R targeting showed antiproliferative activity of EOC cells. However, clinical studies failed to show significant benefit. EOC cells suppress antitumor immune responses by inducing dendritic cell (DC) dysfunction. The IGF1 axis can regulate DC maturation. The current study evaluated involvement of the IGF1 axis in DC differentiation in EOC. Studies were conducted on EOC and on a human monocyte cell line. Tissue microarray analysis (TMA) was performed on 36 paraffin blocks from EOC patients. Expression of IGF1R, p53, Ki67, BRCA1, and DC markers was evaluated using immunohistochemistry. Co-culture of EOC cells with DC pretreated with IGF1R inhibitor blocked cancer cell migration. TMA demonstrated higher rate of IGF1R protein expression in patients with advanced (76.9%) as compared to early (40%) EOC. A negative correlation between IGF1R protein expression and the CD1c marker was found. These findings provide evidence that IGF1R axis inhibition could be a therapeutic strategy for ovarian cancer by restoring DC-mediated antitumor immunity.

Sialyl Lewisx-P-selectin cascade mediates tumor-mesothelial adhesion in ascitic fluid shear flow

Organ-specific colonization suggests that specific cell–cell recognition is essential. Yet, very little is known about this particular interaction. Moreover, tumor cell lodgement requires binding under shear stress, but not static, conditions. Here, we successfully isolate the metastatic populations of cancer stem/tumor-initiating cells (M-CSCs). We show that the M-CSCs tether more and roll slower than the non-metastatic (NM)-CSCs, thus resulting in the preferential binding to the peritoneal mesothelium under ascitic fluid shear stress. Mechanistically, this interaction is mediated by P-selectin expressed by the peritoneal mesothelium. Insulin-like growth factor receptor-1 carrying an uncommon non-sulfated sialyl-Lewis^x (sLe^x) epitope serves as a distinct P-selectin binding determinant. Several glycosyltransferases, particularly α1,3-fucosyltransferase with rate-limiting activity for sLe^x synthesis, are highly expressed in M-CSCs. Tumor xenografts and clinical samples corroborate the relevance of these findings. These data advance our understanding on the molecular regulation of peritoneal metastasis and support the therapeutic potential of targeting the sLe^x-P-selectin cascade.

Tumor cell in the peritoneum are often exposed to shear forces generated by ascitic flow during metastasis. Here, the authors show that metastatic cancer stem cells tether more and roll slower than the non-metastatic counterparts, and that sialyl-Lewis^x -P-selectin axis mediates peritoneal metastasis.

Biologic Mechanisms Linked to Prognosis in Ovarian Cancer that May Be Affected by Aging

The increase of both life expectancy of the Western industrialized population and cancer incidence with aging is expected to result in a rapid expansion of the elderly cancer population, including patients with epithelial ovarian cancer (EOC). Although the survival of patients with EOC has generally improved over the past three decades, this progress has yet to provide benefits for elderly patients. Compared with young age, advanced age has been reported as an adverse prognostic factor influencing EOC. However, contradicting results have been obtained, and the mechanisms underlying this observation are poorly defined. Few papers have been published on the underlying biological mechanisms that might explain this prognosis trend. We provide an extensive review of mechanisms that have been linked to EOC prognosis and/or aging in the published literature and might underlie this relationship in humans.

The role of mTOR in ovarian Neoplasms, polycystic ovary syndrome, and ovarian aging

The mammalian target of rapamycin, mTOR, is a serine-threonine protein kinase downstream of the phosphatidylinositol 3-kinase (PI3K)-AKT axis. The pathway can regulate cell growth, proliferation, and survival by activating ribosomal kinases. Recent studies have implicated the mTOR signaling pathway in ovarian neoplasms, polycystic ovary syndrome (PCOS) and premature ovarian failure (POF). Preclinical investigations have demonstrated that the PI3K/AKT/mTOR pathway is frequently activated in the control of various ovarian functions. mTOR allows cancer cells to escape the normal biochemical system and regulates the balance between apoptosis and survival. Some recent studies have suggested that involvement of the mTOR signaling system is an important pathophysiological basis of PCOS. Overexpression of the mTOR pathway can impair the interaction of cumulus cells, lead to insulin resistance, and affect the growth of follicles directly. The roles of mTOR signaling in follicular development have been extensively studied in recent years; abnormalities in this process lead to a series of pathologies such as POF and infertility. To improve understanding of the role of the mTOR signaling pathway in the pathogenesis and development of ovarian diseases, here we review the roles of mTOR signaling in such diseases and discuss the corresponding therapeutic strategies that target this pathway. Clin. Anat. 31:891-898, 2018. © 2018 Wiley Periodicals, Inc.

Young Adult Cancer: Influence of the Obesity Pandemic

OBJECTIVE

The purpose of this article is to review the association of the obesity pandemic with appearance of cancers in young adults under age 50 and to define potential mechanisms by which obesity may accelerate the development of malignancy.

METHODS

A comprehensive narrative review was performed to integrate preclinical, clinical, and epidemiologic evidence describing the association of obesity with cancer in young adults based on a search of PubMed and Google databases.

RESULTS

Results from more than 100 publications are summarized. Although they differ in age groups analyzed and incidence of obesity, sufficient data exists to suggest an influence of the obesity pandemic on the increase of cancer among young adults.

CONCLUSIONS

Cancer in young adults is occurring with increasing frequency. Overweight and obesity have become major public health issues reaching pandemic proportions. Excess weight is associated with increased cancer risk, morbidity, and mortality. Multiple murine models indicate that obesity not only increases cancer incidence but also accelerates its development. Thus, the possibility exists that overweight and obesity may be contributing to the appearance of specific malignancies at younger ages. This prospect, in association with the worldwide expansion of obesity, suggests an impending explosive increase in obesity-associated cancers in young adults.

Paraoxonase 2 overexpression inhibits tumor development in a mouse model of ovarian cancer

Ovarian cancer (OC) is most lethal malignancy among all gynecological cancer. Large bodies of evidences suggest that mitochondrial-derived ROS play a critical role in the development and progression of OC. Paraoxonase 2 (PON2) is a membrane-associated lactonase with anti-oxidant properties. PON2 deficiency aggravates mitochondrial ROS formation, systemic inflammation, and atherosclerosis. The role of PON2 in cancer development remains unknown. In this report, in human, we identified that PON2 expression is higher in early stages (but not in late stages) of OC when compared to normal tissue. Using a mouse xenograft model of OC, we demonstrate that overexpression of PON2 prevents tumor formation. Mechanistically, PON2 decreases OC cell proliferation by inhibiting insulin like growth factor-1 (IGF-1) expression and signaling. Intriguingly, PON2 reduces c-Jun-mediated transcriptional activation of IGF-1 gene by decreasing mitochondrial superoxide generation. In addition, PON2 impairs insulin like growth factor-1 receptor (IGF-1R) signaling in OC cells by altering cholesterol homeostasis, which resulted in reduced caveolin-1/IGF-1R interaction and IGF-1R phosphorylation. Taken together, we report for the first time that PON2 acts as a tumor suppressor in the early stage of OC by reducing IGF-1 production and its signaling, indicating PON2 activation might be a fruitful strategy to inhibit early stage ovarian tumor.

Phenformin has anti-tumorigenic effects in human ovarian cancer cells and in an orthotopic mouse model of serous ovarian cancer

Obesity and diabetes have been associated with increased risk and worse outcomes in ovarian cancer (OC). The biguanide metformin is used in the treatment of type 2 diabetes and is also believed to have anti-tumorigenic benefits. Metformin is highly hydrophilic and requires organic cation transporters (OCTs) for entry into human cells. Phenformin, another biguanide, was taken off the market due to an increased risk of lactic acidosis over metformin. However, phenformin is not reliant on transporters for cell entry; and thus, may have increased potency as both an anti-diabetic and anti-tumorigenic agent than metformin. Thus, our goal was to evaluate the effect of phenformin on established OC cell lines, primary cultures of human OC cells and in an orthotopic mouse model of high grade serous OC. In three OC cell lines, phenformin significantly inhibited cellular proliferation, induced cell cycle G1 arrest and apoptosis, caused cellular stress, inhibited adhesion and invasion, and activation of AMPK and inhibition of the mTOR pathway. Phenformin also exerted anti-proliferative effects in seven primary cell cultures of human OC. Lastly, phenformin inhibited tumor growth in an orthotopic mouse model of serous OC, coincident with decreased Ki-67 staining and phosphorylated-S6 expression and increased expression of caspase 3 and phosphorylated-AMPK. Our findings demonstrate that phenformin has anti-tumorigenic effects in OC as previously demonstrated by metformin but it is yet to be determined if it is superior to metformin for the potential treatment of this disease.

Genetic variants as ovarian cancer first-line treatment hallmarks: A systematic review and meta-analysis

BACKGROUND

The potential predictive value of genetic polymorphisms in ovarian cancer first-line treatment is inconsistently reported. We aimed to review ovarian cancer pharmacogenetic studies to update and summarize the available data and to provide directions for further research.

METHODS

A systematic review followed by a meta-analysis was conducted on cohort studies assessing the involvement of genetic polymorphisms in ovarian cancer first-line treatment response retrieved through a MEDLINE database search by November 2016. Studies were pooled and summary estimates and 95% confidence intervals (CI) were calculated using random or fixed-effects models as appropriate.

RESULTS

One hundred and forty-two studies gathering 106871 patients were included. Combined data suggested that GSTM1-null genotype patients have a lower risk of death compared to GSTM1-wt carriers, specifically in advanced stages (hazard ratio (HR), 0.68; 95% CI, 0.48-0.97) and when submitted to platinum-based chemotherapy (aHR, 0.61; 95% CI, 0.39-0.94). ERCC1 rs11615 and rs3212886 might have also a significant impact in treatment outcome (aHR, 0.67; 95% CI, 0.51-0.89; aHR, 1.28; 95% CI, 1.01-1.63, respectively). Moreover, ERCC2 rs13181 and rs1799793 showed a distinct ethnic behavior (Asians: aHR, 1.41; 95% CI, 0.80-2.49; aHR, 1.07; 95% CI, 0.62-1.86; Caucasians: aHR, 0.10; 95% CI, 0.01-0.96; aHR, 0.18; 95% CI, 0.05-0.68, respectively).

CONCLUSION(S)

The definition of integrative predictive models should encompass genetic information, especially regarding GSTM1 homozygous deletion. Justifying additional pharmacogenetic investigation are variants in ERCC1 and ERCC2, which highlight the DNA Repair ability to ovarian cancer prognosis. Further knowledge could aid to understand platinum-treatment failure and to tailor chemotherapy strategies.

Increased efficacy of metformin corresponds to differential metabolic effects in the ovarian tumors from obese versus lean mice

Obesity is a significant risk factor for ovarian cancer (OC) and associated with worse outcomes for this disease. We assessed the anti-tumorigenic effects of metformin in human OC cell lines and a genetically engineered mouse model of high grade serous OC under obese and lean conditions. Metformin potently inhibited growth in a dose-dependent manner in all four human OC cell lines through AMPK/mTOR pathways. Treatment with metformin resulted in G1 arrest, induction of apoptosis, reduction of invasion and decreased hTERT expression. In the K18-gT₁₂₁^+/-; p53^fl/fl; Brca1^fl/fl (KpB) mouse model, metformin inhibited tumor growth in both lean and obese mice. However, in the obese mice, metformin decreased tumor growth by 60%, whereas tumor growth was only decreased by 32% in the lean mice (p=0.003) compared to vehicle-treated mice. The ovarian tumors from obese mice had evidence of impaired mitochondrial complex 2 function and energy supplied by omega fatty acid oxidation rather than glycolysis as compared to lean mice, as assessed by metabolomic profiling. The improved efficacy of metformin in obesity corresponded with inhibition of mitochondrial complex 1 and fatty acid oxidation, and stimulation of glycolysis in only the OCs of obese versus lean mice. In conclusion, metformin had anti-tumorigenic effects in OC cell lines and the KpB OC pre-clinical mouse model, with increased efficacy in obese versus lean mice. Detected metabolic changes may underlie why ovarian tumors in obese mice have heightened susceptibility to metformin.

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 Prognostic 97 Chemoresponse Gene Signature in Ovarian Cancer

Patient diagnosis and care would be significantly improved by understanding the mechanisms underlying platinum and taxane resistance in ovarian cancer. Here, we aim to establish a gene signature that can identify molecular pathways/transcription factors involved in ovarian cancer progression, poor clinical outcome, and chemotherapy resistance. To validate the robustness of the gene signature, a meta-analysis approach was applied to 1,020 patients from 7 datasets. A 97-gene signature was identified as an independent predictor of patient survival in association with other clinicopathological factors in univariate [hazard ratio (HR): 3.0, 95% Confidence Interval (CI) 1.66–5.44, p = 2.7E-4] and multivariate [HR: 2.88, 95% CI 1.57–5.2, p = 0.001] analyses. Subset analyses demonstrated that the signature could predict patients who would attain complete or partial remission or no-response to first-line chemotherapy. Pathway analyses revealed that the signature was regulated by HIF1α and TP53 and included nine HIF1α-regulated genes, which were highly expressed in non-responders and partial remission patients than in complete remission patients. We present the 97-gene signature as an accurate prognostic predictor of overall survival and chemoresponse. Our signature also provides information on potential candidate target genes for future treatment efforts in ovarian cancer.

The Crosstalk between Ovarian Cancer Stem Cell Niche and the Tumor Microenvironment

Ovarian cancer is one of the most important causes of cancer-related death among women in the world. Despite advances in ovarian cancer treatment, 70–80% of women who initially respond to therapy eventually relapse and die. There is evidence that a small population of cells within the tumors called cancer stem cells (CSCs) could be responsible for treatment failure due to their enhanced chemoresistance and tumorigenicity. These cells reside in a niche that maintains the principal properties of CSCs. These properties are associated with the capacity of CSCs to interact with different cells of the tumor microenvironment including mesenchymal stem cells, endothelial cells, immune cells, and fibroblasts, promoting cancer progression. This interaction can be mediated by cytokines, growth factors, lipids, and/or extracellular vesicles released in the CSC niche. In this review, we will discuss how the interaction between ovarian CSCs and the tumor microenvironment can contribute to the maintenance of the CSC niche and consequently to tumor progression in ovarian cancer.

Active targeting co-delivery system based on hollow mesoporous silica nanoparticles for antitumor therapy in ovarian cancer stem-like cells

The combination of nanocarriers and chemotherapy drugs can release the chemotherapy drugs to the tumor tissue, which can enhance the antitumor effect and reduce the adverse reactions at the same time. In this study, a co-delivery system based on hollow mesoporous silica nanoparticles (HMSN) was developed and characterized. We also investigated the in vitro effect of this system on CD117+CD44+A2780 cell line. HMSN was selected as the nanocarrier, with -COOH modified on the surface and doxorubicin (DOX), NVP-AEW 541 (NVP) loaded inside. IGF‑1R was chosen as the drug target, apoptosis rate and expression of cyclin B1, Bax, Bcl-xl, p-Akt were used to evaluate the antitumor effect of HMSN‑COOH@DOX fluorescence NVP. The HMSN co-delivery system was successfully synthesized with encapsulation efficiency of 37% (DOX) and 44% (NVP), and high PH-sensitive property was observed. The apoptosis rate of CD117+CD44+A2780 ovarian cancer stem-like cells treated by HMSN co-delivery system were almost 3 times higher than those of the free drugs group. The expression of Bax was significantly increased while Bcl-xl, and p-Akt reduced (P≤0.05). These data indicate that the co-delivery system demonstrated a high efficiency in promoting apoptosis in ovarian cancer stem-like cells by targeting IGF‑1R, but further study is still needed.

C-reactive protein and insulin-like growth factor-1 in differential diagnosis of ascites

BACKGROUND AND AIM

Insulin-like growth factor-1 (IGF-1) and C-reactive protein (CRP) are produced mainly by the liver; the output of these markers in response to inflammatory processes may be affected in patients with hepatic dysfunction. This may explain the differences in IGF-1 and CRP values in patients with non-portal and portal hypertension ascites. We aimed to evaluate serum and ascitic fluid IGF-1 and CRP as diagnostic markers in the differential diagnosis of benign and malignant ascites.

METHODS

In this prospective study, 398 consecutive patients with ascites were included. Serum and ascitic fluid levels of IGF-1 and CRP were measured using an enzyme-linked immunosorbent assay.

RESULTS

Patients were divided into group 1, due to benign ascites (n = 324), and group 2, due to malignant ascites (n = 74). Serum and ascitic IGF-1 were significantly increased in malignant ascites than benign ascites group [305 ± 65.7 ng/mL vs 95 ± 53.8 ng/mL; P < 0.001 and 288 ± 54.7 ng/mL vs 83.2 ± 36.7 ng/mL; P < 0.001], respectively. Serum and ascitic CRP were significantly higher in malignant ascites than benign ascites patients [12.8 ± 6.3 mg/mL vs 6.1 ± 4.9 mg/mL; P < 0.001 and 5.1 ± 2.2 mg/mL vs 1.6 ± 1.3 mg/mL; P < 0.001], respectively. At a cutoff value of 309.4 ng/mL and 7.8 mg/mL, serum IGF-1 and CRP had (95.1%, 81%) sensitivity and (88.6%, 75.5%) specificity for detecting malignant ascites [area under the curve: 0.932, 0.845], respectively. At a cutoff value of 291.6 ng/mL and 2.6 mg/mL, ascitic IGF-1 and CRP had (94.6%, 84%) sensitivity and (83.2%, 80.3%) specificity for detecting malignant ascites (area under the curve: 0.911, 0.893) correspondingly.

CONCLUSION

Elevated serum and ascitic fluid IGF-1 and CRP levels were associated with malignant ascites.

Meta-dimensional data integration identifies critical pathways for susceptibility, tumorigenesis and progression of endometrial cancer

Endometrial Cancer (EC) is one of the most common female cancers. Genome-wide association studies (GWAS) have been investigated to identify genetic polymorphisms that are predictive of EC risks. Here we utilized a meta-dimensional integrative approach to seek genetically susceptible pathways that may be associated with tumorigenesis and progression of EC. We analyzed GWAS data obtained from Connecticut Endometrial Cancer Study (CECS) and identified the top 20 EC susceptible pathways. To further verify the significance of top 20 EC susceptible pathways, we conducted pathway-level multi-omics analyses using EC exome-Seq, RNA-Seq and survival data, all based on The Cancer Genome Atlas (TCGA) samples. We measured the overall consistent rankings of these pathways in all four data types. Some well-studied pathways, such as p53 signaling and cell cycle pathways, show consistently high rankings across different analyses. Additionally, other cell signaling pathways (e.g. IGF-1/mTOR, rac-1 and IL-5 pathway), genetic information processing pathway (e.g. homologous recombination) and metabolism pathway (e.g. sphingolipid metabolism) are also highly associated with EC risks, diagnosis and prognosis. In conclusion, the meta-dimensional integration of EC cohorts has suggested some common pathways that may be associated from predisposition, tumorigenesis to progression.

Targeted therapy in ovarian cancer

Among female-specific cancers worldwide, ovarian cancer is the leading cause of death from gynecologic malignancy in the western world. Despite radical surgery and initial high response rates to first-line chemotherapy, up to 70% of patients experience relapses with a median progression-free survival of 12-18 months. There remains an urgent need for novel targeted therapies to improve clinical outcomes in ovarian cancer. This review aims to assess current understanding of targeted therapy in ovarian cancer and evaluate the evidence for targeting growth-dependent mechanisms involved in its pathogenesis. Of the many targeted therapies currently under evaluation, the most promising strategies developed thus far are antiangiogenic agents and PARP inhibitors.

Associations of Serum Isoflavone, Adiponectin and Insulin Levels with Risk for Epithelial Ovarian Cancer: Results of a Case-control Study

BACKGROUND

The aim of this study was to examine the association of serum isoflavones, adiponectin, and insulin levels with ovarian cancer risk.

MATERIALS AND METHODS

We gathered cases with histologically confirmed epithelial ovarian cancer at Sapporo Medical University Hospital from October 2010 to September 2012. Potential controls were recruited from female inpatients without any history of cancer or diabetes mellitus in different wards of the same hospital over the same period of time. Serum isoflavones, adiponectin, and insulin levels were measured in order to estimate associations with ovarian cancer risk in a case-control study. Data from 71 cases and 80 controls were analyzed with a logistic regression model adjusting for known risk factors.

RESULTS

A significant reduction in ovarian cancer risk was observed for the high tertile of serum daidzein level versus the low (Ptrend<0.001). A significant reduction in ovarian cancer risk was also observed for the high tertile of serum glycitein level versus the low (Ptrend=0.005). Furthermore, a significant reduction in ovarian cancer risk was observed for the high tertile of serum adiponectin level versus the low (Ptrend=0.004). Conversely, serum insulin level showed significantly elevated risk for ovarian cancer with the high tertile versus the low Ptrend<0.001).

CONCLUSIONS

Decreased serum isoflavones levels, such as those for daidzein and glycitein, decreased serum adiponectin levels, and increased serum insulin levels could be shown to be associated with elevated risk of ovarian cancer.

EphA4-deleted microenvironment regulates cancer development and leukemoid reaction of the isografted 4T1 murine breast cancer via reduction of an IGF1 signal

EphA4 belongs to the largest family of receptor tyrosine kinases (RTKs). Although EphA4 is highly expressed in the central nervous system, EphA4 has also been implicated in cancer progression. Most of the studies focus on the expression and function in tumor cells. It is unknown whether EphA4‐deleted microenvironment affects tumor progression. Some of cancers in animals and humans, such as 4T1 cancer cells, are known to produce a large amount of granulocyte colony‐stimulating factors (G‐CSF/Csf3) which can stimulate myeloproliferation, such as myeloid‐derived suppressor cells (MDSCs) leading to a poor recipient prognosis. We isografted 4T1 breast cancer cells into both EphA4‐knockout and control wild‐type female littermate mice. The results showed that the EphA4‐deleted host could inhibit primary tumor growth and tumor metastasis mainly by decreasing the amount of IGF1 synthesis in the circulation and locally tissues. The EphA4‐deleted microenvironment and delayed tumor development reduced the production of G‐CSF resulting in the decrease of splenomegaly and leukemoid reaction including MDSCs, which in turn inhibit the tumor progression. This inhibition can be reversed by supplying the mice with IGF1. However, an excess of IGF1 supply over demand to the control mice could not further accelerate the tumor growth and metastasis. A better understanding and re‐evaluation of the main role of IGF1 in regulating tumor progression could further enhance our cognition of the tumor development niche. Our findings demonstrated that EphA4‐deleted microenvironment impairs tumor‐supporting conditions. Conclusion: Host EphA4 expression regulates cancer development mainly via EphA4‐mediated IGF1 synthesis signal. Thus, targeting this signaling pathway may provide a potential therapeutic option for cancer treatment.

Quantitative analysis of insulin-like growth factor 2 receptor and insulin-like growth factor binding proteins to identify control mechanisms for insulin-like growth factor 1 receptor phosphorylation

Background

The insulin-like growth factor (IGF) system impacts cellular development by regulating proliferation, differentiation, and apoptosis, and is an attractive therapeutic target in cancer. The IGF system is complex, with two ligands (IGF1, IGF2), two receptors (IGF1R, IGF2R), and at least six high affinity IGF-binding proteins (IGFBPs) that regulate IGF ligand bioavailability. While the individual components of the IGF system are well studied, the question of how these different components integrate as a system to regulate cell behavior is less clear.

Results

To analyze the relative importance of different mechanisms that control IGF network activity, we developed a mass-action kinetic model incorporating cell surface binding, phosphorylation, and intracellular trafficking events. The model was calibrated and validated using experimental data collected from OVCAR5, an immortalized ovarian cancer cell line. We then performed model analysis to examine the ability of IGF2R or IGFBPs to counteract phosphorylation of IGF1R, a critical step for IGF network activation. This analysis suggested that IGF2R levels would need to be 320-fold greater than IGF1R in order to decrease pIGF1R by 25 %, while IGFBP levels would need to be 390-fold greater. Analysis of The Cancer Genome Atlas (TCGA) data set suggested that this level of overexpression is unlikely for IGF2R in ovarian, breast, and colon cancer. In contrast, IGFBPs can likely reach these levels, suggesting that IGFBPs are the more critical regulator of IGF1R network activity. Levels of phosphorylated IGF1R were insensitive to changes in parameters regulating the IGF2R arm of the network.

Conclusions

Using a mass-action kinetic model, we determined that IGF2R plays a minor role in regulating the activity of IGF1R under a variety of conditions and that due to their high expression levels, IGFBPs are the dominant mechanism to regulating IGF network activation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12918-016-0263-6) contains supplementary material, which is available to authorized users.

High-grade serous ovarian cancer cell lines exhibit heterogeneous responses to growth factor stimulation

Background

The factors driving the onset and progression of ovarian cancer are not well understood. Recent reports have identified cell lines that are representative of the genomic pattern of high-grade serous ovarian cancer (HGSOC), in which greater than 90 % of tumors have a mutation in TP53. However, many of these representative cell lines have not been widely used so it is unclear if these cell lines capture the variability that is characteristic of the disease.

Methods

We investigated six TP53-mutant HGSOC cell lines (Caov3, Caov4, OV90, OVCA432, OVCAR3, and OVCAR4) for migration, MMP2 expression, proliferation, and VEGF secretion, behaviors that play critical roles in tumor progression. In addition to comparing baseline variation between the cell lines, we determined how these behaviors changed in response to four growth factors implicated in ovarian cancer progression: HB-EGF, NRG1β, IGF1, and HGF.

Results

Baseline levels of each behavior varied across the cell lines and this variation was comparable to that seen in tumors. All four growth factors impacted cell proliferation or VEGF secretion, and HB-EGF, NRG1β, and HGF impacted wound closure or MMP2 expression in at least two cell lines. Growth factor-induced responses demonstrated substantial heterogeneity, with cell lines sensitive to all four growth factors, a subset of the growth factors, or none of the growth factors, depending on the response of interest. Principal component analysis demonstrated that the data clustered together based on cell line rather than growth factor identity, suggesting that response is dependent on intrinsic qualities of the tumor cell rather than the growth factor.

Conclusions

Significant variation was seen among the cell lines, consistent with the heterogeneity of HGSOC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12935-015-0263-4) contains supplementary material, which is available to authorized users.

Suppression of Homologous Recombination by insulin-like growth factor-1 inhibition sensitizes cancer cells to PARP inhibitors

Background

Impairment of homologous recombination (HR) is found in close to 50 % of ovarian and breast cancer. Tumors with BRCA1 mutations show increased expression of the Insulin-like growth factor type 1 receptor (IGF-1R). We previously have shown that inhibition of IGF-1R results in growth inhibition and apoptosis of ovarian tumor cells. In the current study, we aimed to investigate the correlation between HR and sensitivity to IGF-1R inhibition. Further, we hypothesized that IGF-1R inhibition might sensitize HR proficient cancers to Poly ADP ribose polymerase (PARP) inhibitors.

Methods

Using ovarian and breast cancer cellular models with known BRCA1 status, we evaluated their HR functionality by RAD51 foci formation assay. The 50 % lethal concentration (LC50) of Insulin-like growth factor type 1 receptor kinase inhibitor (IGF-1Rki) in these cells was assessed, and western immunoblotting was performed to determine the expression of proteins involved in the IGF-1R pathway. Moreover, IGF-1R inhibitors were added on HR proficient cell lines to assess mRNA and protein expression of RAD51 by qPCR and western blot. Also, we explored the interaction between RAD51 and Insulin receptor substance 1 (IRS-1) by immunoprecipitation. Next, combination effect of IGF-1R and PARP inhibitors was evaluated by clonogenic assay.

Results

Cells with mutated/methylated BRCA1 showed an impaired HR function, and had an overactivation of the IGF-1R pathway. These cells were more sensitive to IGF-1R inhibition compared to HR proficient cells. In addition, the IGF-IR inhibitor reduced RAD51 expression at mRNA and protein levels in HR proficient cells, and sensitized these cells to PARP inhibitor.

Conclusion

Targeting IGF-1R might lead to improved personalized therapeutic approaches in cancer patients with HR deficiency. Targeting both PARP and IGF-1R might increase the clinical efficacy in HR deficient patients and increase the population of patients who may benefit from PARP inhibitors.

Early pregnancy IGF-I and placental GH and risk of epithelial ovarian cancer: A nested case-control study

Insulin-like growth factor-I (IGF-I) signaling may promote ovarian tumor development by exerting mitotic, antiapoptotic and proangiogenic effects. During pregnancy, maternal production of IGF-I is regulated by placental growth hormone (GH). Parity is an established protective factor for ovarian cancer, however, no prior study has evaluated placental GH and IGF-I in pregnancy and epithelial ovarian cancer (EOC). Prior prospective studies on the association between IGF-I and EOC in nonpregnant populations were inconclusive and did not address associations in subtypes of EOC. Among members of the Finnish Maternity Cohort and the Northern Sweden Maternity Cohort, we identified 1,045 EOC cases, diagnosed after recruitment (1975-2008) and before March 2011 and 2,658 individually matched controls. Placental GH and IGF-I were measured in serum from the last pregnancy before EOC diagnosis or selection as control. We used conditional logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for tertiles and a doubling of hormone concentrations. Higher IGF-I was associated with a nonsignificant decrease in risk for invasive [ORT3 vs. T1 : 0.79 (0.62-1.02); ptrend  = 0.07] and endometrioid tumors [ORT3 vs. T1 : 0.55 (0.28-1.07); ptrend  = 0.07]. The protective association between higher IGF-I levels and risk of invasive EOC was stronger in analyses limited to women aged <55 years at diagnosis [ORT3 vs. T1 : 0.74 (0.57-0.96); ptrend  = 0.03]. Our study provides the first data on placental GH and IGF-I in pregnancy and EOC risk overall and by subtype. Our data suggest higher IGF-I levels in pregnancy may be associated with lower risk of invasive and endometrioid EOC.

Metformin and gynecologic cancers

IMPORTANCE

The obese population in the United States is reaching epic proportions, and obesity is linked to an increased risk for several cancers including gynecologic cancers. Obesity is not only a risk factor but also a marker of poor prognosis. It is crucial to develop novel treatment strategies to target this population. Metformin is a biguanide drug, typically used for diabetes treatment, currently being studied to evaluate its role in the treatment and prevention of gynecologic cancers.

OBJECTIVE

The aim of this study was to review the underlying biologic mechanisms of metformin's antitumorigenic effects. We assessed the epidemiologic and preclinical data that support the use of metformin in patients with endometrial and ovarian cancer. Finally, we reviewed current clinical trials that incorporate metformin as a prevention or treatment strategy for gynecologic cancers.

EVIDENCE ACQUISITION

A thorough search of PubMed for all current literature was performed. All preclinical, clinical, and epidemiologic reviews were evaluated across all cancers, with a focus on gynecologic cancer.

RESULTS

The preclinical, epidemiologic, and clinical data evaluated in this review are strongly supportive of the use of metformin for the prevention and treatment of gynecologic cancer. On the basis of these data, centers are currently enrolling for clinical trials using metformin in patients diagnosed with gynecologic malignancies.

CONCLUSIONS AND RELEVANCE

The data supporting the use of metformin in the prevention and treatment of cancers are building, including that of endometrial and ovarian cancer. The association between obesity, insulin resistance, as well as increased risk and poor outcomes in endometrial and ovarian cancer patients makes metformin an attractive agent for the prevention and treatment of these diseases.

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.

Insulin-like growth factor-1 mRNA isoforms and insulin-like growth factor-1 receptor mRNA expression in chronic hepatitis C

AIM: To evaluate the expression of different insulin-like growth factor (IGF)-1 mRNA isoforms and IGF-1 receptor (IGF-1R) mRNA in hepatitis C virus (HCV)-infected livers.

METHODS: Thirty-four liver biopsy specimens from chronic hepatitis C (CH-C) patients were obtained before anti-viral therapy. Inflammatory activity (grading) and advancement of fibrosis (staging) were evaluated using a modified point scale of METAVIR. The samples were analyzed using quantitative real-time PCR technique. From fragments of liver biopsies and control liver that were divided and ground in liquid nitrogen, RNA was isolated using RNeasy Fibrous Tissue Mini Kit according to the manufacturer’s instruction. Expression levels of IGF-1 mRNA isoforms (IGF-1A, IGF-1B, IGF-1C, P1, and P2) and IGF-1R mRNA were determined through normalization of copy numbers in samples as related to reference genes: glyceraldehyde-3-phosphate dehydrogenase and hydroxymethylbilane synthase. Results on liver expression of the IGF-1 mRNA isoforms and IGF-1R transcript were compared to histological alterations in liver biopsies and with selected clinical data in the patients. Statistical analysis was performed using Statistica PL v. 9 software.

RESULTS: The study showed differences in quantitative expression of IGF-1 mRNA variants in HCV-infected livers, as compared to the control. Higher relative expression of total IGF-1 mRNA and of IGF-1 mRNAs isoforms (P1, A, and C) in HCV-infected livers as compared to the control were detected. Within both groups, expression of the IGF-1A mRNA isoform significantly prevailed over expressions of B and C isoforms. Expression of P1 mRNA was higher than that of P2 only in CH-C. Very high positive correlations were detected between reciprocal expressions of IGF-1 mRNA isoforms P1 and P2 (r = 0.876). Expression of P1 and P2 mRNA correlated with IGF-1A mRNA (r = 0.891; r = 0.821, respectively), with IGF-1B mRNA (r = 0.854; r = 0.813, respectively), and with IGF-1C mRNA (r = 0.839; r = 0.741, respectively). Expression of IGF-1A mRNA significantly correlated with isoform B and C mRNA (r = 0.956; r = 0.869, respectively), and B with C isoforms (r = 0.868) (P < 0.05 in all cases). Lower expression of IGF-1A and B transcripts was noted in the more advanced liver grading (G2) as compared to G1. Multiple negative correlations were detected between expression of various IGF-1 transcripts and clinical data (e.g., alpha fetoprotein, HCV RNA, steatosis, grading, and staging). Expression of IGF-1R mRNA manifested positive correlation with grading and HCV-RNA.

CONCLUSION: Differences in quantitative expression of IGF-1 mRNA isoforms in HCV-infected livers, as compared to the control, suggest that HCV may induce alteration of IGF-1 splicing profile.

A novel neutralizing antibody targeting pregnancy-associated plasma protein-a inhibits ovarian cancer growth and ascites accumulation in patient mouse tumorgrafts

The majority of ovarian cancer patients acquire resistance to standard platinum chemotherapy and novel therapies to reduce tumor burden and ascites accumulation are needed. Pregnancy-associated plasma protein-A (PAPP-A) plays a key role in promoting insulin-like growth factor (IGF) pathway activity, which directly correlates to ovarian cancer cell transformation, growth, and invasiveness. Herein, we evaluate PAPP-A expression in tumors and ascites of women with ovarian cancer, and determine the antitumor efficacy of a neutralizing monoclonal PAPP-A antibody (mAb-PA) in ovarian cancer using primary patient ovarian tumorgrafts ("Ovatars"). PAPP-A mRNA expression in patient ovarian tumors correlated with poor outcome and was validated as a prognostic surrogate in Ovatar tumors. Following confirmation of mAb-PA bioavailability and target efficacy in vivo, the antitumor efficacy of mAb-PA in multiple Ovatar tumor models was examined and the response was found to depend on PAPP-A expression. Strikingly, the addition of mAb-PA to standard platinum chemotherapy effectively sensitized platinum-resistant Ovatar tumors. PAPP-A protein in ascites was also assessed in a large cohort of patients and very high levels were evident across the entire sample set. Therefore, we evaluated targeted PAPP-A inhibition as a novel approach to managing ovarian ascites, and found that mAb-PA inhibited the development, attenuated the progression, and induced the regression of Ovatar ascites. Together, these data indicate PAPP-A as a potential palliative and adjunct therapeutic target for women with ovarian cancer.

Impact of isoflurane on malignant capability of ovarian cancer in vitro

BACKGROUND

Metastatic recurrence of ovarian cancer is the foremost cause of postoperative mortality. With recent research indicating that inhalation of anaesthetics may influence cancer cell behaviour, this study investigated the effects of isoflurane on the expression of tumorigenic markers and proliferative capacity in ovarian cancer cells.

METHODS

Ovarian cancer (SK-OV3) cells were cultured and then exposed to 2% isoflurane for 2 h. The expression of markers involved in cell proliferation, angiogenesis, and migration were assessed up to 24 h after treatment using immunofluorescence staining, western blotting, and flow cytometry. The effects of isoflurane on in vitro angiogenesis and migration were also determined.

RESULTS

Isoflurane exposure significantly increased insulin-like growth factor (IGF)-1 and IGF-1R expression, cell cycle progression, and cell proliferation in SK-OV3 cells. Increased expression of the angiogenic markers vascular endothelial growth factor (VEGF) by 56% (P<0.05) and angiopoietin-1 by 62% (P<0.05) was also observed 24 h after isoflurane exposure together with an enhanced in vitro angiogenesis. Cell migration was significantly increased after exposure to isoflurane together with increased production of both matrix metalloproteinases 2 and 9 (both P<0.05) by almost five-fold relative to control. These effects were abolished when IGF-1R signalling was blocked either by neutralizing antibody or by small interfering RNA.

CONCLUSIONS

Our data indicate that isoflurane increases the malignant potential of ovarian cancer cells through the up-regulation of markers associated with the cell cycle, proliferation, and angiogenesis. This study warrants further investigations.

Estrogen signaling crosstalk: Implications for endocrine resistance in ovarian cancer

Resistance to anti-estrogen therapies is a prominent challenge in the treatment of ovarian cancer. Tumors develop endocrine resistance by acquiring adaptations that help them rely on alternative oncogenic signaling cascades, which crosstalk with estrogen signaling pathways. An understanding of estrogen signaling crosstalk with these growth promoting cascades is essential in order to maximize efficacy of anti-estrogen treatments in ovarian cancer. Herein, we provide an overview of estrogen signaling in ovarian cancer and discuss the major challenges associated with anti-estrogen therapies. We also review what is currently known about how genomic and non-genomic estrogen signaling pathways crosstalk with several major oncogenic signaling cascades. The insights provided here illustrate existing strategies for targeting endocrine resistant ovarian tumors and may help identify new strategies to improve the treatment of this disease.

Analysis of the quantitative balance between insulin-like growth factor (IGF)-1 ligand, receptor, and binding protein levels to predict cell sensitivity and therapeutic efficacy

Background

The insulin-like growth factor (IGF) system impacts cell proliferation and is highly activated in ovarian cancer. While an attractive therapeutic target, the IGF system is complex with two receptors (IGF1R, IGF2R), two ligands (IGF1, IGF2), and at least six high affinity IGF-binding proteins (IGFBPs) that regulate the bioavailability of IGF ligands. We hypothesized that a quantitative balance between these different network components regulated cell response.

Results

OVCAR5, an immortalized ovarian cancer cell line, were found to be sensitive to IGF1, with the dose of IGF1 (i.e., the total mass of IGF1 available) a more reliable predictor of cell response than ligand concentration. The applied dose of IGF1 was depleted by both cell-secreted IGFBPs and endocytic trafficking, with IGFBPs sequestering up to 90% of the available ligand. To explore how different variables (i.e., IGF1, IGFBPs, and IGF1R levels) impacted cell response, a mass-action steady-state model was developed. Examination of the model revealed that the level of IGF1-IGF1R complexes per cell was directly proportional to the extent of proliferation induced by IGF1. Model analysis suggested, and experimental results confirmed, that IGFBPs present during IGF1 treatment significantly decreased IGF1-mediated proliferation. We utilized this model to assess the efficacy of IGF1 and IGF1R antibodies against different network compositions and determined that IGF1R antibodies were more globally effective due to the receptor-limited state of the network.

Conclusions

Changes that affect IGF1R occupancy have predictable effects on IGF1-induced proliferation and our model captured these effects. Analysis of this model suggests that IGF1R antibodies will be more effective than IGF1 antibodies, although the difference was minimal in conditions with low levels of IGF1 and IGFBPs. Examining how different components of the IGF system influence cell response will be critical to improve our understanding of the IGF signaling network in ovarian cancer.

Circulating IGF system and treatment outcome in epithelial ovarian cancer

Aggressive epithelial ovarian cancers (EOCs) frequently progress and become fatal, even when cytoreduction surgery plus platinum-based chemotherapy are performed. Thus, the early detection of high-risk subgroups is important in order to provide opportunities for better treatment outcomes, using alternative therapeutic strategies. This study aimed to explore the expression of circulating IGF system components and their relationship with treatment outcome in EOC. We included 228 patients with a median follow-up time of 44 months at two tertiary centers. There were 68 cancer deaths and 108 cases of cancer progression in the cohort. Preoperative serum levels of total IGF1, IGF2, IGF-binding protein 2 (IGFBP2), and IGFBP3 were analyzed using an ELISA and were then converted into an IGF1:IGFBP3 molar ratio. The risks of mortality and progression were estimated using Cox regression models in univariate and multivariate analyses. Our results showed that high IGF1, IGF2, and IGFBP3 levels were significantly associated with an early cancer stage, non-serous histology, and optimal cytoreduction. High IGFBP2 levels were associated with an advanced stage and serous histology. Overall and progression-free survival durations were significantly better among patients with high IGF1 (P=0.003 and P=0.001), IGF2 (P=0.003 and P=0.02), or IGFBP3 levels (P=0.02 and P=0.008). In multivariate analysis, serum IGFBP2 levels were significantly associated with increased risk of mortality (hazard ratio=1.84, 95% CI: 1.07-3.18, P=0.03), indicating that IGFBP2 could be used as an early predictor of EOC-related mortality. The combination of elevated IGFBP2 and reduced IGF1 levels at diagnosis could further facilitate the identification of a patient subgroup with the worst prognosis.

Antisense oligonucleotide suppression of human IGF-1R inhibits the growth and survival of in vitro cultured epithelial ovarian cancer cells

Background

Preclinical evaluation of the anti-neoplastic activity of antisense oligonucleotide (AS) suppression of human insulin-like growth factor I receptor (IGF-IR) in human epithelial ovarian cancer (EOC).

Methods

Ovarian cancer cells from 36 patients with EOC were investigated under serum-free tissue culture conditions. IGF-I production was evaluated by standard ELISA. IGF-IR and phosphorylated IRS-1, AKT, and MAP kinase expression and protein levels were evaluated by immunohistochemistry and Western blotting. Cancer cell growth and proliferation assays were performed in triplicates using MTT assay. Apoptosis was evaluated by TUNNEL assay.

Results

All ovarian cancer tissue samples tested produced IGF-I and expressed IGF-IR, supporting the existence of an autocrine loop. Treatment of primary ovarian cancer cell lines with an IGF-1R AS inhibited growth and proliferation and decreased clonogenicity in soft agar assay. AS treatment was demonstrated to inhibit the expression of IGF-1R and decrease the concentration of phosphorylated IRS-1, AKT, and MAP kinase signaling protein downstream of the IGF-IR. We also observed that the IGF-1R AS sensitized cancer cell lines to cisplatin in vitro through the PI3K pathway.

Conclusions

IGF-IR enhances the proliferation and tumorigenicity of human ovarian cancer cells and inhibition of IGF-IR by AS oligonucleotide treatment potentiates the activity of cisplatin in vitro. Therefore, IGF-1R is a potential molecular target in ovarian cancer.

Hospicells promote upregulation of the ATP-binding cassette genes by insulin-like growth factor-I via the JAK2/STAT3 signaling pathway in an ovarian cancer cell line

Interaction between tumor cells and their microenvironment has a crucial role in the development, progression and drug resistance of cancer. Our objective was to confirm the role of Hospicells, which are stromal cells from the cancer microenvironment, in drug resistance and tumor cell growth. We demonstrated that soluble factors secreted by Hospicells activate several genes and upregulate the JAK/STAT signaling pathway in ovarian cancer cell lines. Hospicells express all insulin-like growth factor (IGF) family as detected by gene array, RT-PCR, protein array and immunocytochemistry. While focusing attention on the microenvironment, we considered the role of IGF-I in proliferation and survival of ovarian cancer cells. Indeed, IGF-I is a major regulator of different stages of cancer development. We studied the effect of exogenously added IGF-I on the regulation of ATP-binding cassette (ABC) genes (MDR1, MRP1, MRP2, MRP3, MRP5 and BCRP) in the ovarian cancer cell line OVCAR3 and validated the results obtained using the IGF-IR antagonist picropodophyllin. IGF-I regulates the expression of ABC genes in OVCAR3 cells via the PI3-kinase, MEK and JAK2/STAT3 signaling pathways. The OVCAR3 cell line when co-cultured with Hospicells showed a marked degree of drug resistance. The drug resistance observed could be amplified with exogenous IGF-I. Addition of IGF-IR inhibitor, however, reduced the degree of resistance in these exposed cells. Cells that were treated with anticancer drugs and then exposed to IGF-I showed an increase in drug resistance and, thereby, an increase in cell survival. This observation indicates that drug resistance of OVCAR3 cells increases when there is synergy between OVCAR3 cells and Hospicells and it is amplified when IGF-I was exogenously added. In conclusion, inhibition of IGF-IR and targeting of the JAK2/STAT3 signaling pathway can be a target for ovarian cancer therapy.

Recent alcohol consumption and risk of incident ovarian carcinoma: a pooled analysis of 5,342 cases and 10,358 controls from the Ovarian Cancer Association Consortium

BACKGROUND

Studies evaluating the association between alcohol intake and ovarian carcinoma (OC) are inconsistent. Because OC and ovarian borderline tumor histologic types differ genetically, molecularly and clinically, large numbers are needed to estimate risk associations.

METHODS

We pooled data from 12 case-control studies in the Ovarian Cancer Association Consortium comprising 5,342 OC cases, 1,455 borderline tumors and 10,358 controls with quantitative information on recent alcohol intake to estimate odds ratios (OR) and 95% confidence intervals (CI) according to frequencies of average daily intakes of beer, wine, liquor and total alcohol.

RESULTS

Total alcohol intake was not associated with all OC: consumption of >3 drinks per day compared to none, OR=0.92, 95% CI=0.76-1.10, P trend=0.27. Among beverage types, a statistically non-significant decreased risk was observed among women who consumed >8 oz/d of wine compared to none (OR=0.83, 95% CI=0.68-1.01, P trend=0.08). This association was more apparent among women with clear cell OC (OR, 0.43; 95% CI, 0.22-0.83; P trend=0.02), although based on only 10 cases and not statistically different from the other histologic types (P value for statistical heterogeneity between histologic types = 0.09). Statistical heterogeneity of the alcohol- and wine-OC associations was seen among three European studies, but not among eight North American studies. No statistically significant associations were observed in separate analyses evaluating risk with borderline tumors of serous or mucinous histology. Smoking status did not significantly modify any of the associations.

CONCLUSIONS

We found no evidence that recent moderate alcohol drinking is associated with increased risk for overall OC, or that variation in risk is associated strongly with specific histologic types. Understanding modifiable causes of these elusive and deadly cancers remains a priority for the research community.

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.

Vegetarian diets and the incidence of cancer in a low-risk population

BACKGROUND

Cancer is the second leading cause of death in the United States. Dietary factors account for at least 30% of all cancers in Western countries. As people do not consume individual foods but rather combinations of them, the assessment of dietary patterns may offer valuable information when determining associations between diet and cancer risk.

METHODS

We examined the association between dietary patterns (non-vegetarians, lacto, pesco, vegan, and semi-vegetarian) and the overall cancer incidence among 69,120 participants of the Adventist Health Study-2. Cancer cases were identified by matching to cancer registries. Cox proportional hazard regression analysis was conducted to estimate hazard ratios, with "attained age" as the time variable.

RESULTS

A total of 2,939 incident cancer cases were identified. The multivariate HR of overall cancer risk among vegetarians compared with non-vegetarians was statistically significant [HR, 0.92; 95% confidence interval (CI), 0.85-0.99] for both genders combined. Also, a statistically significant association was found between vegetarian diet and cancers of the gastrointestinal tract (HR, 0.76; 95% CI, 0.63-0.90). When analyzing the association of specific vegetarian dietary patterns, vegan diets showed statistically significant protection for overall cancer incidence (HR, 0.84; 95% CI, 0.72-0.99) in both genders combined and for female-specific cancers (HR, 0.66; 95% CI, 0.47-0.92). Lacto-ovo-vegetarians appeared to be associated with decreased risk of cancers of the gastrointestinal system (HR, 0.75; 95% CI, 0.60-0.92).

CONCLUSION

Vegetarian diets seem to confer protection against cancer.

IMPACT

Vegan diet seems to confer lower risk for overall and female-specific cancer than other dietary patterns. The lacto-ovo-vegetarian diets seem to confer protection from cancers of the gastrointestinal tract.

The PI3K/Akt/mTOR signaling pathway mediates insulin-like growth factor 1-induced E-cadherin down-regulation and cell proliferation in ovarian cancer cells

Insulin-like growth factor 1 (IGF1) is produced by ovarian cancer cells and it has been suggested that it plays an important role in tumor progression. In this study, we report that IGF1 treatment down-regulated E-cadherin by up-regulating E-cadherin transcriptional repressors, Snail and Slug, in human ovarian cancer cells. The pharmacological inhibition of phosphatidylinositol-3-kinase (PI3K) and mammalian target of rapamycin (mTOR) suggests that PI3K/Akt/mTOR signaling is required for IGF1-induced E-cadherin down-regulation. Moreover, IGF1 up-regulated Snail and Slug expression via the PI3K/Akt/mTOR signaling pathway. Finally, IGF1-induced cell proliferation was abolished by inhibiting PI3K/Akt/mTOR signaling. This study demonstrates a novel mechanism in which IGF1 down-regulates E-cadherin expression through the activation of PI3K/Akt/mTOR signaling and the up-regulation of Snail and Slug in human ovarian cancer cells.

Insulin receptor and cancer

The widespread epidemic of obesity and type 2 diabetes has raised concern for the impact of these disorders as risk factors for cancer and has renewed the interest for studies regarding the involvement of hyperinsulinemia and insulin receptor (IR) in cancer progression. Overexpression of IR in cancer cells may explain their increased sensitivity to hyperinsulinemia. Moreover, IR isoform A (IR-A) together with autocrine production of its ligand IGF2 is emerging as an important mechanism of normal and cancer stem cell expansion and is a feature of several malignancies. De novo activation of the IR-A/IGF2 autocrine loop also represents a mechanism of resistance to anticancer therapies. Increasing knowledge of the IR role in cancer has important implications for cancer prevention, which should include control of insulin resistance and hyperinsulinemia in the population and meticulous evaluation of new antidiabetic drugs for their metabolic:mitogenic ratio. We are now aware that several anticancer treatments may induce or worsen insulin resistance that may limit therapy efficacy. Future anticancer therapies need to target the IR-A pathway in order to inhibit the tumor promoting effect of IR without impairing the metabolic effect of insulin.

Genetic variation in insulin-like growth factor 2 may play a role in ovarian cancer risk

The insulin-like growth factor (IGF) signaling axis plays an important role in cancer biology. We hypothesized that genetic variation in this pathway may influence risk of ovarian cancer. A three-center study of non-Hispanic whites including 1880 control women, 1135 women with invasive epithelial ovarian cancer and 321 women with borderline epithelial ovarian tumors was carried out to test the association between tag single-nucleotide polymorphisms (tSNPs) (n=58) in this pathway and risk of ovarian cancer. We found no association between variation in IGF1, IGFBP1 or IGFBP3 and risk of invasive disease, whereas five tSNPs in IGF2 were associated with risk of invasive epithelial ovarian cancer at P<0.05 and followed-up one of the associated SNPs. We conducted genotyping in 3216 additional non-Hispanic white cases and 5382 additional controls and were able to independently replicate our initial findings. In the combined set of studies, rs4320932 was associated with a 13% decreased risk of ovarian cancer per copy of the minor allele carried (95% confidence interval 0.81-0.93, P-trend=7.4 × 10(-5)). No heterogeneity of effect across study centers was observed (p(het)=0.25). IGF2 is emerging as an important gene for ovarian cancer; additional genotyping is warranted to further confirm these associations with IGF2 and to narrow down the region harboring the causal SNP.

P-cadherin cooperates with insulin-like growth factor-1 receptor to promote metastatic signaling of gonadotropin-releasing hormone in ovarian cancer via p120 catenin

Gonadotropin-releasing hormone (GnRH) is a potent prometastatic factor in ovarian cancer, but the intracellular signaling events are not well understood. The classical Gα(q)-phospholipase C signal transduction pathway known to operate in the pituitary is not involved in GnRH actions at non-pituitary targets. Here we showed that GnRH treatment of ovarian cancer cells led to a rapid and remarkable tyrosine phosphorylation of p120 catenin (p120(ctn)), which was mediated by P-cadherin. The use of P-cadherin small interfering RNA or neutralizing antibodies to inhibit P-cadherin expression and function resulted in diminished p120(ctn) activation, confirming that the effect was P-cadherin specific. On exploring how P-cadherin, which lacks intrinsic kinase activity, might regulate the activation of p120(ctn), we found that P-cadherin could induce the ligand-independent activation of insulin-like growth factor-1 receptor (IGF-1R). Inhibition of IGF-1R expression or its activity significantly inhibited GnRH-induced p120(ctn) activation, and the subsequent cell migration and invasion. In addition, we showed that IGF-1R regulation by P-cadherin was associated with complex formation between IGF-1R and P-cadherin, and this regulation was also observed to be in vivo correlated with metastasis. Furthermore, using a mouse model of ovarian cancer metastasis, GnRH receptor knockdown was shown to diminish peritoneal dissemination of tumors and ascites formation. These findings suggest for the first time that GnRH can initiate an outside-in p120(ctn) signal transduction through the cross-talk between P-cadherin and IGF-1R, thus providing a novel molecular mechanism by which GnRH may control the high level of aggressiveness and invasion and metastasis potential that are characteristic of ovarian cancer.

PTK6 regulates IGF-1-induced anchorage-independent survival

BACKGROUND

Proteins that are required for anchorage-independent survival of tumor cells represent attractive targets for therapeutic intervention since this property is believed to be critical for survival of tumor cells displaced from their natural niches. Anchorage-independent survival is induced by growth factor receptor hyperactivation in many cell types. We aimed to identify molecules that critically regulate IGF-1-induced anchorage-independent survival.

METHODS AND RESULTS

We conducted a high-throughput siRNA screen and identified PTK6 as a critical component of IGF-1 receptor (IGF-1R)-induced anchorage-independent survival of mammary epithelial cells. PTK6 downregulation induces apoptosis of breast and ovarian cancer cells deprived of matrix attachment, whereas its overexpression enhances survival. Reverse-phase protein arrays and subsequent analyses revealed that PTK6 forms a complex with IGF-1R and the adaptor protein IRS-1, and modulates anchorage-independent survival by regulating IGF-1R expression and phosphorylation. PTK6 is highly expressed not only in the previously reported Her2(+) breast cancer subtype, but also in high grade ER(+), Luminal B tumors and high expression is associated with adverse outcomes.

CONCLUSIONS

These findings highlight PTK6 as a critical regulator of anchorage-independent survival of breast and ovarian tumor cells via modulation of IGF-1 receptor signaling, thus supporting PTK6 as a potential therapeutic target for multiple tumor types. The combined genomic and proteomic approaches in this report provide an effective strategy for identifying oncogenes and their mechanism of action.

Anti-tumor effects of adenovirus containing human growth hormone sequences in a mouse model of human ovarian cancer

Women with ovarian cancer have a low survival rate and develop resistance to chemotherapy, so new approaches to treatment are needed. We unexpectedly found administration of a replication-deficient adenovirus containing human growth hormone sequences (AdXGH) was beneficial in a mouse model of human ovarian cancer. Intraperitoneal injections of AdXGH prolonged median survival from a mean of 31 ± 1.2 to 40 ± 1.4 days in immunodeficient SCID mice given SKOV3.ip1 human ovarian cancer cells in the peritoneal cavity. Adenovirus containing human prolactin or del32-71growth hormone sequences had no effect. Repeated injection of growth hormone or implantation of tablets with sustained growth hormone release did not increase survival. Control mice had overlapping tumors throughout the peritoneal cavity and liver and frequent lung metastases 24 days after tumor cell injection. Mice that received two injections of AdXGH had no lung metastases. Mice that received four injections had no lung or liver metastases and peritoneal fibrosis. They did not survive longer than mice that received two injections, but they had enlarged livers with hepatocellular changes, indicating that a limitation of increasing the dose is liver toxicity.