Metformin and gynecologic cancers

The Roles of Tricellular Tight Junction Protein Angulin-1/Lipolysis-Stimulated Lipoprotein Receptor (LSR) in Endometriosis and Endometrioid-Endometrial Carcinoma

Tight junction proteins play roles beyond permeability barriers functions and control cell proliferation and differentiation. The relation between tight junctions and the signal transduction pathways affects cell growth, invasion and migration. Abnormality of tight junction proteins closely contributes to epithelial mesenchymal transition (EMT) and malignancy of various cancers. Angulin-1/lipolysis-stimulated lipoprotein receptor (LSR) forms tricellular contacts that has a barrier function. Downregulation of angulin-1/LSR correlates with the malignancy in various cancers, including endometrioid-endometrial carcinoma (EEC). These alterations have been shown to link to not only multiple signaling pathways such as Hippo/YAP, HDAC, AMPK, but also cell metabolism in ECC cell line Sawano. Moreover, loss of angulin-1/LSR upregulates claudin-1, and loss of apoptosis stimulating p53 protein 2 (ASPP2) downregulates angulin-1/LSR. Angulin-1/LSR and ASPP2 concentrate at both midbody and centrosome in cytokinesis. In EEC tissues, angulin-1/LSR and ASPP2 are reduced and claudin-2 is overexpressed during malignancy, while in the tissues of endometriosis changes in localization of angulin-1/LSR and claudin-2 are seen. This review highlights how downregulation of angulin-1/LSR promotes development of endometriosis and EEC and discusses about the roles of angulin-1/LSR and its related proteins, including claudins and ASPP2.

TOM40 Inhibits Ovarian Cancer Cell Growth by Modulating Mitochondrial Function Including Intracellular ATP and ROS Levels

TOM40 is a channel-forming subunit of translocase, which is essential for the movement of proteins into the mitochondria. We found that TOM40 was highly expressed in epithelial ovarian cancer (EOC) cells at both the transcriptional and translational levels; its expression increased significantly during the transformation from normal ovarian epithelial cells to EOC (p < 0.001), and TOM40 expression negatively correlated with disease-free survival (Hazard ratio = 1.79, 95% Confidence inerval 1.16–2.78, p = 0.009). TOM40 knockdown decreased proliferation in several EOC cell lines and reduced tumor burden in an in vivo xenograft mouse model. TOM40 expression positively correlated with intracellular adenosine triphosphate (ATP) levels. The low ATP and high reactive oxygen species (ROS) levels increased the activity of AMP-activated protein kinase (AMPK) in TOM40 knockdown EOC cells. However, AMPK activity did not correlate with declined cell growth in TOM40 knockdown EOC cells. We found that metformin, first-line therapy for type 2 diabetes, effectively inhibited the growth of EOC cell lines in an AMPK-independent manner by inhibiting mitochondria complex I. In conclusion, TOM40 positively correlated with mitochondrial activities, and its association enhances the proliferation of ovarian cancer. Also, metformin is an effective therapeutic option in TOM40 overexpressed ovarian cancer than normal ovarian epithelium.

Metformin Promotes Anti-tumor Biomarkers in Human Endometrial Cancer Cells

Metformin (MET) is increasingly implicated in reducing the incidence of multiple cancer types in patients with diabetes. However, similar effects of MET in non-diabetic women with endometrial cancer (EC) remain unknown. In a pilot study, obese non-diabetic women diagnosed with type 1, grade 1/2 EC, and consenting to participate were randomly assigned to receive MET or no MET (control (CON)) during the pre-surgical window between diagnosis and hysterectomy. Endometrial tumors obtained at surgery (MET, n = 4; CON, n = 4) were analyzed for proliferation (Ki67), apoptosis (TUNEL), and nuclear expression of ERα, PGR, PTEN, and KLF9 proteins in tumor glandular epithelial (GE) and stromal (ST) cells. The percentages of immunopositive cells for PGR and for KLF9 in GE and for PTEN in ST were higher while those for ERα in GE but not ST were lower, in tumors of MET vs. CON patients. The numbers of Ki67- and TUNEL-positive cells in tumor GE and ST did not differ between groups. In human Ishikawa endometrial cancer cells, MET treatment (60 μM) decreased cell numbers and elicited distinct temporal changes in ESR1, KLF9, PGR, PGR-B, KLF4, DKK1, and other tumor biomarker mRNA levels. In the context of reduced KLF9 expression (by siRNA targeting), MET rapidly amplified PGR, PGR-B, and KLF4 transcript levels. Our findings suggest that MET acts directly in EC cells to modify steroid receptor expression and signaling network and may constitute a preventative strategy against EC in high-risk non-diabetic women.

Phenformin as an Anticancer Agent: Challenges and Prospects

Currently, there is increasing evidence linking diabetes mellitus (especially type 2 diabetes mellitus) with carcinogenesis through various biological processes, such as fat-induced chronic inflammation, hyperglycemia, hyperinsulinemia, and angiogenesis. Chemotherapeutic agents are used in the treatment of cancer, but in most cases, patients develop resistance. Phenformin, an oral biguanide drug used to treat type 2 diabetes mellitus, was removed from the market due to a high risk of fatal lactic acidosis. However, it has been shown that phenformin is, with other biguanides, an authentic tumor disruptor, not only by the production of hypoglycemia due to caloric restriction through AMP-activated protein kinase with energy detection (AMPK) but also as a blocker of the mTOR regulatory complex. Moreover, the addition of phenformin eliminates resistance to antiangiogenic tyrosine kinase inhibitors (TKI), which prevent the uncontrolled metabolism of glucose in tumor cells. In this review, we evidence the great potential of phenformin as an anticancer agent. We thoroughly review its mechanism of action and clinical trial assays, specially focusing on current challenges and future perspectives of this promising drug.

No. 344-Opportunistic Salpingectomy and Other Methods of Risk Reduction for Ovarian/Fallopian Tube/Peritoneal Cancer in the General Population

OBJECTIVE

This guideline reviews the potential benefits of opportunistic salpingectomy to prevent the development of high grade serous cancers (HGSC) of the ovary/fallopian tube/peritoneum based on current evidence supporting the fallopian tube origin of disease.

INTENDED USERS

Gynaecologists, obstetricians, family doctors, registered nurses, nurse practitioners, residents, and health care providers.

TARGET POPULATION

Adult women (18 and older): OPTIONS: Women considering hysterectomy who wish to retain their ovaries in situ have traditionally also retained their fallopian tubes. In addition, women undergoing permanent surgical sterilization have usually undergone tubal ligation using various methods rather than undergoing surgical removal of the entire fallopian tube.

EVIDENCE

For the sections "Evidence Supporting the Hypothesis That HGSC Originates in the Fallopian Tube" and "Current Literature on the Effects and Safety of Opportunistic Salpingectomy," relevant studies were searched in PubMed, Medline, and the Cochrane Systematic Reviews using the following terms, either alone or in combination, with the search limited to English language materials: "high grade serous cancers ovary," "fallopian tube," "peritoneum," "opportunistic salpingectomy," "epithelial ovarian cancers," "origin," "tubal carcinoma in situ," "BRCA mutation," "prophylactic salpingectomy," "inflammation," "clear cell," and "endometrioid." The initial search was performed in March 2015 with a final literature search in March 2016. Relevant evidence was selected for inclusion in the following order: meta-analyses, systematic reviews, guidelines, randomized controlled trials, prospective cohort studies, observational studies, non-systematic reviews, case series, and reports. The total number of studies identified was 458, and 56 studies were included in this review. For the section "Other Factors Influencing the Risk of Developing "Ovarian" Cancers" a general Medline search was carried out using the terms "ovarian neoplasm" and "prevention." The search included papers published from December 2005 to March 2016. Meta-analyses were preferentially selected except where no such review was found. Additional searches for each subheading were also conducted (e.g., "ovarian neoplasm" and "tubal ligation.") Additional significant articles were identified through cross-referencing the identified reviews. For the search for "ovarian neoplasm" and "prevention," 10 meta-analyses were identified. For the search for "ovarian neoplasm" and "tubal ligation," an additional 4 meta-analyses were identified.

VALIDATION METHODS

The content and recommendations were drafted and agreed on by the principal authors. The Executive and Board of the Society of Gynecologic Oncology of Canada reviewed the content and submitted comments for consideration, and the Board of the SOGC approved the final draft for publication. The quality of evidence was rated using the criteria described in the Grading of Recommendations Assessment, Development and Evaluation methodology framework (Table 1). The interpretation of strong and weak recommendations is described in Table 2. The summary of findings is available on request.

BENEFITS, HARMS, AND/OR COSTS

The addition of opportunistic salpingectomy to a planned hysterectomy or permanent sterilization did not increase rates of hospital readmission (OR 0.91, 95% CI 0.75 to 1.10 and OR 0.8, 95% CI 0.56 to 1.21, respectively) or blood transfusions (OR 0.86, 95% CI 0.67 to 1.10 and OR 0.75, 95% CI 0.32 to 1.73, respectively) but did increase the overall operating time (by 16 minutes and 10 minutes, respectively) in a retrospective review of 43 931 women. The risk of repeat surgery for tubal pathology among women with retained fallopian tubes after hysterectomy was at least doubled (OR 2.13, 95% CI 1.88 to 2.42 in a population-based study of 170 000 women). If general gynaecologists were to consider removal of fallopian tubes at the time of every hysterectomy and sterilization procedure with referral of all patients with HGSC for hereditary cancer counselling and genetic testing, experts project a potential reduction in the rate of HGSC by 40% over the next 20 years.

GUIDELINE UPDATE

Evidence will be reviewed 5 years after publication to decide whether all or part of the guideline should be updated. However, if important new evidence is published prior to the 5-year cycle, the review process may be accelerated for a more rapid update of some recommendations.

SPONSORS

This guideline was developed with resources funded by the Society of Gynecologic Oncology of Canada and SOGC.

SUMMARY STATEMENTS

RECOMMENDATIONS.

Risk-reducing medications for primary breast cancer: a network meta-analysis

BACKGROUND

Breast cancer is the most frequently occurring malignancy and the second cause of death for cancer in women. Cancer prevention agents (CPAs) are a promising approach to reduce the burden of breast cancer. Currently, two main types of CPAs are available: selective estrogen receptor modulators (SERMs, such as tamoxifen and raloxifene) and aromatase inhibitors (AIs, such as exemestane and anastrozole).

OBJECTIVES

To assess the efficacy and acceptability of single CPAs for the prevention of primary breast cancer, in unaffected women, at an above-average risk of developing breast cancer.Using a network meta-analysis, to rank single CPAs, based on their efficacy and acceptability (an endpoint that is defined as the inverse of CPA-related toxicity).

SEARCH METHODS

We searched the Cochrane Breast Cancer Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, World Health Organization's International Clinical Trials Registry Platform (WHO ICTRP), and ClinicalTrials.gov on 17 August 2018. We handsearched reference lists to identify additional relevant studies.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that enrolled women without a personal history of breast cancer but with an above-average risk of developing a tumor. Women had to be treated with a CPA and followed up to record the occurrence of breast cancer and adverse events.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and conducted risk of bias assessments of the included studies, and assessed the certainty of the evidence using GRADE. Outcome data included incidence of breast carcinoma (both invasive and in situ carcinoma) and adverse events (both overall and severe toxicity). We performed a conventional meta-analysis (for direct comparisons of a single CPA with placebo or a different CPA) and network meta-analysis (for indirect comparisons).

MAIN RESULTS

We included six studies enrolling 50,927 women randomized to receive one CPA (SERMs: tamoxifen or raloxifene, or AIs: exemestane or anastrozole) or placebo. Three studies compared tamoxifen and placebo, two studies compared AIs (exemestane or anastrozole) versus placebo, and one study compared tamoxifen versus raloxifene. The risk of bias was low for all RCTs.For the tamoxifen versus placebo comparison, tamoxifen likely resulted in a lower risk of developing breast cancer compared to placebo (risk ratio (RR) 0.68, 95% confidence interval (CI) 0.62 to 0.76; 3 studies, 22,832 women; moderate-certainty evidence). In terms of adverse events, tamoxifen likely increased the risk of severe toxicity compared to placebo (RR 1.28, 95% CI 1.12 to 1.47; 2 studies, 20,361 women; moderate-certainty evidence). In particular, women randomized to receive tamoxifen experienced a higher incidence of both endometrial carcinoma (RR 2.26, 95% CI 1.52 to 3.38; high-certainty evidence) and thromboembolism (RR 2.10, 95% CI 1.14 to 3.89; high-certainty evidence) compared to women who received placebo.For the AIs versus placebo comparison, AIs (exemestane or anastrozole) reduced the risk of breast cancer by 53% (RR 0.47, 95% CI 0.35 to 0.63; 2 studies, 8424 women; high-certainty evidence). In terms of adverse events, AIs increased the risk of severe toxicity by 18% (RR 1.18, 95% CI 1.09 to 1.28; 2 studies, 8352 women; high-certainty evidence). These differences were sustained especially by endocrine (e.g. hot flashes), gastrointestinal (e.g. diarrhea), and musculoskeletal (e.g. arthralgia) adverse events, while there were no differences in endometrial cancer or thromboembolism rates between AIs and placebo.For the tamoxifen versus raloxifene comparison, raloxifene probably performed worse than tamoxifen in terms of breast cancer incidence reduction (RR 1.25, 95% CI 1.09 to 1.43; 1 study, 19,490 women; moderate-certainty evidence), but its use was associated with lower toxicity rates (RR 0.87, 95% CI 0.80 to 0.95; 1 study, 19,490 women; moderate-certainty evidence), particularly relating to incidence of endometrial cancer and thromboembolism.An indirect comparison of treatment effects allowed us to compare the SERMs and AIs in this review. In terms of efficacy, AIs (exemestane or anastrozole) may have reduced breast cancer incidence slightly compared to tamoxifen (RR 0.67, 95% CI 0.46 to 0.98; 5 RCTs, 31,256 women); however, the certainty of evidence was low. A lack of model convergence did not allow us to analyze toxicity data.

AUTHORS' CONCLUSIONS

For women with an above-average risk of developing breast cancer, CPAs can reduce the incidence of this disease. AIs appear to be more effective than SERMs (tamoxifen) in reducing the risk of developing breast cancer. AIs are not associated with an increased risk of endometrial cancer and thromboembolic events. However, long-term data on toxicities from tamoxifen are available while the follow-up toxicity data on unaffected women taking AIs is relatively short. Additional data from direct comparisons are needed to fully address the issues of breast cancer prevention by risk-reducing medications, with special regards to acceptability (i.e. the benefit/harm ratio).

Targeted Multiplex Gene Expression Profiling to Measure High-Fat Diet and Metformin Effects on Fetal Gene Expression in a Mouse Model

BACKGROUND

Maternal obesity and excessive gestational weight gain (GWG) are associated with delivery of a large-for-gestational-age infant. We used a high-fat diet (HFD) mouse model to separate the effect of maternal obesity from excessive GWG on fetal growth. Our objective was to identify fetal gene expression changes in an HFD and control diet (CD) mouse model with and without metformin exposure.

STUDY DESIGN

Normal weight timed-pregnant (Female Friend virus B) strain mice were allocated on day e0.5 to receive HFD or CD and either plain water or metformin (2.5 mg/mL in drinking water). Dams were euthanized on day e17.5 and fetal livers harvested and frozen at -80°C. RNA was extracted and hybridized to a customized 96-gene Nanostring panel focused on angiogenesis, inflammation, and growth gene expression. Fetal liver gene expression was compared between metformin and plain water groups using analysis of variance. Significant differences in gene expression, defined by a false discovery controlled q value <0.01, were then analyzed using Ingenuity pathway analysis (IPA).

RESULTS

In HFD-fed dams, compared to controls, the metformin-treated group had significantly lower fetal weight and 39 differentially expressed liver genes; 15 (38%) were in the growth/angiogenesis gene expression network. IPA predicted that fetal liver gene upregulation associated with metformin exposure is a result of metformin inhibition of the common upstream regulator, phosphatase and tensin homolog ( PTEN).

CONCLUSIONS

Metformin-exposed fetuses from dams fed HFD and CD have significant gene expression differences in genes specific to growth and angiogenesis pathways in the fetal liver. Diet alone did not alter fetal liver gene expression.

The roles of tricellular tight junction protein lipolysis-stimulated lipoprotein receptor in malignancy of human endometrial cancer cells

Lipolysis-stimulated lipoprotein receptor (LSR) has been identified as a novel molecular constituent of tricellular contacts that have a barrier function for the cellular sheet. LSR recruits tricellulin (TRIC), which is the first molecular component of tricellular tight junctions. Knockdown of LSR increases cell motility and invasion of certain cancer cells. However, the behavior and the roles of LSR in endometrial cancer remain unknown. In the present study, we investigated the behavior and roles of LSR in normal and endometrial cancer cells in vivo and in vitro. In endometriosis and endometrial cancer, LSR was observed not only in the subapical region but also throughout the lateral region as well as in normal endometrial epithelial cells in the secretory phase, and LSR in the cancer was reduced in correlation with the malignancy. Knockdown of LSR by the siRNA in cells of the endometrial cancer cell line Sawano, induced cell migration, invasion and proliferation, while TRIC relocalized from the tricellular region to the bicellular region at the membrane. In Sawano cells and normal HEEs, a decrease of LSR induced by leptin and an increase of LSR induced by adiponectin and the drugs for type 2 diabetes metformin and berberine were observed via distinct signaling pathways including JAK2/STAT. In Sawano cells, metformin and berberine prevented cell migration and invasion induced by downregulation of LSR by the siRNA and leptin treatment. The dissection of the mechanism in the downregulation of endometrial LSR during obesity is important in developing new diagnostic and therapy for endometrial cancer.

Endometrial cancer evolution: new molecular-biologic types and hormonal-metabolic shifts

The question hidden in the title of this manuscript (whether the topic develops or remains constant) is important for all areas of science. It is also a serious problem for endometrial cancer (EC) study. In recent times the incidence of EC gradually increases in parallel with obesity epidemics. The main point of this review was evaluation of changes in EC area in last few decades, which are not only seen in tumor incidence, but also in its biology, hormonal-metabolic characteristics of patients and in the ratio of risk and anti-risk factors. One can hope that data accumulated recently and summarized here under the notion of EC evolution will find its use for advancement of EC prevention and treatment.

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.

Missed therapeutic and prevention opportunities in women with BRCA-mutated epithelial ovarian cancer and their families due to low referral rates for genetic counseling and BRCA testing: A review of the literature

Answer questions and earn CME/CNE Fifteen percent of women with epithelial ovarian cancer have inherited mutations in the BRCA breast cancer susceptibility genes. Knowledge of her BRCA status has value both for the woman and for her family. A therapeutic benefit exists for the woman with cancer, because a new family of oral drugs, the poly ADP-ribose polymerase (PARP) inhibitors, has recently been approved, and these drugs have the greatest efficacy in women who carry the mutation. For her family, there is the potential to prevent ovarian cancer in those carrying the mutation by using risk-reducing surgery. Such surgery significantly reduces the chance of developing this, for the most part, incurable cancer. Despite these potential benefits, referral rates for genetic counseling and subsequent BRCA testing are low, ranging from 10% to 30%, indicating that these therapeutic and prevention opportunities are being missed. The authors have reviewed the relevant available literature. Topics discussed are BRCA and its relation to ovarian cancer, the rates of referral for genetic counseling/BRCA testing, reasons for these low rates, potential strategies to improve on those rates, lack of effectiveness of current screening strategies, the pros and cons of risk-reducing surgery, other prevention options, and the role and value of PARP inhibitors. CA Cancer J Clin 2017;67:493-506. © 2017 American Cancer Society.

Cause-specific mortality in endometrioid endometrial cancer patients with type 2 diabetes using metformin or other types of antidiabetic medication

AIM

To obtain further evidence of the association between metformin or other types of antidiabetic medication (ADM) and mortality from endometrial cancer (EC) and other causes of death in patients with endometrioid EC and type 2 diabetes (T2D).

MATERIALS AND METHODS

A retrospective cohort of women with existing T2D and diagnosed with endometrioid EC from 1998 to 2011, obtained from a nationwide diabetes database (FinDM), were included in the study. Cumulative mortality from EC and that from other causes was described by using the Aalen-Johansen estimator. Cause-specific mortality rates were analyzed by using Cox models, and adjusted hazard ratios (HRs) with 95% confidence intervals (95% CIs) were estimated in relation to the use of different forms of ADM during the three-year period preceding EC diagnosis.

RESULTS

From the FinDM cohort we identified 1215 women diagnosed with endometrioid EC, of whom 19% were metformin users, 12% were users of other types of oral antidiabetic medication, 25% used other types of oral antidiabetic medication plus metformin, 26% used insulin and 14% had no antidiabetic medication. Mortality from EC was not found to be different in women using metformin (HR 0.89, 95% Cl 0.52-1.54) but mortality from other causes was lower (HR 0.52, 95% Cl 0.31-0.88) compared with women using other types of oral ADM.

CONCLUSIONS

Our findings are inconclusive as to the possible effect of metformin on the prognosis of endometrioid EC in women with T2D. However, use of metformin may reduce mortality from other causes.

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.

Metformin use and survival outcomes in endometrial cancer: a systematic review and meta-analysis

Previous studies have evaluated the effects of metformin use on survival outcomes in endometrial cancer, but their results are inconsistent. We conducted a systematic review and meta-analysis to provide a quantitative assessment of the drug's effects based on available evidence. We searched PubMed, Embase, and the Cochrane Central Register of Controlled Trials to identify relevant studies that evaluated the association between metformin use on survival outcomes in endometrial cancer. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated to evaluate the association of metformin use with overall survival and with progression-free survival using a fixed-effects model. A total of nine studies involving 2,016 patients with endometrial cancer were identified. In a meta-analysis of eight studies involving 1,594 individuals, metformin use was associated with significant improvements in overall survival (HR, 0.51; 95% CI, 0.41 to 0.64). Metformin users similarly showed improved progression-free survival in a meta-analysis of two studies involving 632 individuals (HR, 0.63; 95% CI, 0.46 to 0.87). In conclusion, endometrial cancer patients who use metformin show improved overall survival and progression-free survival. Further studies are required to confirm the full potential effects of metformin use on survival outcomes in endometrial cancer.

N o 344-Salpingectomie opportuniste et autres méthodes pour réduire le risque de cancer de l'ovaire, de la trompe de Fallope et du péritoine dans la population générale

OBJECTIF

La présente directive clinique examine les avantages potentiels de la salpingectomie opportuniste pour prévenir le développement du cancer séreux de grade élevé de l'ovaire, de la trompe de Fallope et du péritoine à la lumière de données probantes actuelles selon lesquelles ce type de cancer prendrait naissance dans la trompe de Fallope.

UTILISATEURS CIBLES

Gynécologues, obstétriciens, médecins de famille, infirmières autorisées, infirmières praticiennes, résidents et fournisseurs de soins de santé.

POPULATION CIBLE

Femmes adultes (18 ans et plus) : OPTIONS: Les femmes envisageant une hystérectomie et souhaitant conserver leurs ovaires conservent généralement aussi leurs trompes de Fallope. De plus, celles qui subissent une chirurgie de stérilisation permanente subissent habituellement aussi une ligature des trompes selon des méthodes variées plutôt qu'un retrait chirurgical complet des trompes. RéSULTATS: Les sections « Données probantes appuyant l'hypothèse selon laquelle les CSGE prendraient naissance dans la trompe de Fallope » et « Articles récents sur les répercussions et la sûreté de la salpingectomie opportuniste » reposent sur des études pertinentes rédigées en anglais, qui ont été repérées dans PubMed, Medline et la Cochrane Database of Systematic Reviews à l'aide des termes suivants, seuls ou combinés : high grade serous cancers ovary, fallopian tube, peritoneum, opportunistic salpingectomy, epithelial ovarian cancers, origin, tubal carcinoma in situ, BRCA mutation, prophylactic salpingectomy, inflammation, clear cell et endometrioid. La recherche initiale a été menée en mars 2015, et une dernière recherche a été effectuée en mars 2016. Dans l'ordre, les données probantes pertinentes ont été tirées de méta-analyses, de revues de la littérature, de directives, d'essais cliniques randomisés, d'études de cohorte prospectives, d'études d'observation, de revues non systématiques, d'études de série de cas ainsi que de rapports. Au total, 458 études ont été repérées, et 56 ont été retenues pour la présente directive. Pour la section « Autres facteurs influant sur le risque de développer un cancer de ″l'ovaire″ », une recherche générale a été effectuée dans Medline à partir des termes ovarian neoplasm et prevention. Ont été inclus dans cette recherche des articles rédigés entre décembre 2005 et mars 2016. Les méta-analyses ont été privilégiées lorsque possible. Des recherches supplémentaires ont également été menées pour chaque sous-descripteurs (p. ex., ovarian neoplasm et tubal ligation). D'autres articles pertinents ont été ciblés au moyen d'une vérification des références des revues de la littérature retenues. Les termes ovarian neoplasm et prevention ont permis de repérer 10 méta-analyses; les termes ovarian neoplasm et tubal ligation, 4 méta-analyses. MéTHODES DE VALIDATION: Le contenu et les recommandations ont été rédigés et acceptés par les auteurs principaux. La direction et le conseil de la Société de gynéco-oncologie du Canada ont examiné le contenu et soumis des commentaires, puis le Conseil d'administration de la SOGC a approuvé la version finale avant publication. La qualité des données probantes a été évaluée à partir des critères de l'approche GRADE (Grading of Recommendations Assessment, Development and Evaluation) (tableau 1). L'interprétation des recommandations solides et conditionnelles est décrite dans le tableau 2. Le résumé des conclusions peut être fourni sur demande. AVANTAGES, INCONVéNIENTS ET COûTS: L'ajout d'une salpingectomie opportuniste à une hystérectomie ou à une procédure de stérilisation permanente prévue n'a pas entraîné une augmentation des taux de réadmission à l'hôpital (RC : 0,91; IC à 95 % : 0,75-1, 10 et RC : 0,8; IC à 95 % : 0,56-1,21, respectivement) ou de transfusion sanguine (RC : 0,86; IC à 95 % : 0,67-1,10 et RC : 0,75; IC à 95 % : 0,32-1,73, respectivement), mais il a entraîné une hausse de la durée des opérations (de 16 minutes et de 10 minutes, respectivement) selon une étude rétrospective portant sur 43 931 femmes. Le risque de subir des interventions répétées pour une pathologie tubaire chez les femmes ayant conservé leurs trompes de Fallope après une hystérectomie était au moins deux fois plus élevé (RC : 2,13; IC à 95 % : 1,88-2,42, selon une étude fondée sur une population de 170 000 femmes). Selon des experts, si les gynécologues généralistes envisageaient systématiquement de retirer les trompes de Fallope lors d'une hystérectomie ou d'une procédure de stérilisation et d'aiguiller toutes les patientes aux prises avec un CSGE vers une consultation en oncologie génétique et un dépistage génétique, le taux de CSGE pourrait diminuer de 40 % au cours des 20 prochaines années. MISE à JOUR DE DIRECTIVES CLINIQUES: Une revue des données probantes sera menée cinq ans après la publication de la présente directive clinique afin de déterminer si une mise à jour complète ou partielle s'impose. Cependant, si de nouvelles données probantes importantes sont publiées avant la fin du cycle de cinq ans, le processus pourrait être accéléré afin que certaines recommandations soient mises à jour rapidement.

PARRAINS

La présente directive clinique a été élaborée à l'aide de ressources financées par la Société de gynéco-oncologie du Canada et la SOGC. DéCLARATIONS SOMMAIRES: RECOMMANDATIONS.

A SEER-Medicare analysis of the impact of metformin on overall survival in ovarian cancer

OBJECTIVE

Determine whether metformin use is associated with improved survival in patients with ovarian, fallopian tube or primary peritoneal cancer.

METHODS

All patients with a diagnosis of first epithelial ovarian cancer from 2007 to 2011 in the combined SEER-Medicare database were identified from the SEER registry primary site codes. Comorbidities, procedures and cancer treatment ICD-9 and HCPCS codes were used to search the Medicare claims files. Medication use was determined with National Drug Codes using the Medicare Part D event files. The primary outcome, overall survival, was assessed between metformin users and non-users using a Cox Proportional Hazards survival model. To control for confounding, metformin users were matched to non-metformin users using propensity scores. Effect of dosage on survival was assessed using discrete time survival analysis with pooled logistic regression (PLR).

RESULTS

There were 2291 cases that met our inclusion criteria. Of these, 180 (7.9%) had been on metformin. The median age was 73years, with the majority of the population being White (83.5%) and treated with primary surgery (74.1%). Metformin use was not associated with overall survival in the entire cohort (HR 0.96, 95% CI 0.75-1.23) or in the matched sample cohort (HR 0.88, 95% CI 0.66-1.17). However, exploratory regression with time-varying coefficients suggests a protective metformin effect for women alive after 30months follow-up (HR=0.37, 95% 0.16-0.87).

CONCLUSION

No statistically significant association was observed between metformin use and overall survival in a matched cohort of 360 ovarian cancer patients. However, exploratory modeling suggests metformin use may be protective in a certain subgroup of patients.

Efficacy of metformin for advanced-stage endometrial cancer: A case report

The paradigm of obesity, diabetes mellitus and insulin resistance possibly plays a critical role in the pathogenesis of endometrial cancer (EC). Impaired glucose tolerance and insulin resistance may play a direct or facilitating role in the neoplastic transformation of the endometrium, whereas antidiabetic therapy, particularly with metformin, has been suggested to inhibit EC progression. We herein present the case of a patient with EC who received metformin monotherapy due to complications after undergoing surgery. At 45 months after the introduction of metformin treatment, the patient had no complaints and continued receiving metformin without signs of tumor recurrence. As metformin is widely used among diabetic patients and in ongoing clinical trials in cancer patients, the aforementioned results deserve further clinical investigation.

Obesity and Cancer Mechanisms: Cancer Metabolism

Obesity is a risk factor for cancer development and is associated with poor prognosis in multiple tumor types. The positive energy balance linked with obesity induces a variety of systemic changes including altered levels of insulin, insulin-like growth factor-1, leptin, adiponectin, steroid hormones, and cytokines. Each of these factors alters the nutritional milieu and has the potential to create an environment that favors tumor initiation and progression. Although the complete ramifications of obesity as it relates to cancer are still unclear, there is convincing evidence that reducing the magnitude of the systemic hormonal and inflammatory changes has significant clinical benefits. This review will examine the changes that occur in the obese state and review the biologic mechanisms that connect these changes to increased cancer risk. Understanding the metabolic changes that occur in obese individuals may also help to elucidate more effective treatment options for these patients when they develop cancer. Moving forward, targeted clinical trials examining the effects of behavioral modifications such as reduced carbohydrate intake, caloric restriction, structured exercise, and/or pharmacologic interventions such as the use of metformin, in obese populations may help to reduce their cancer risk.

NT1014, a novel biguanide, inhibits ovarian cancer growth in vitro and in vivo

BACKGROUND

NT1014 is a novel biguanide and AMPK activator with a high affinity for the organic cation-specific transporters, OCT1 and OCT3. We sought to determine the anti-tumorigenic effects of NT1014 in human ovarian cancer cell lines as well as in a genetically engineered mouse model of high-grade serous ovarian cancer.

METHODS

The effects of NT1014 and metformin on cell proliferation were assessed by MTT assay using the human ovarian cancer cell lines, SKOV3 and IGROV1, as well as in primary cultures. In addition, the impact of NT1014 on cell cycle progression, apoptosis, cellular stress, adhesion, invasion, glycolysis, and AMPK activation/mTOR pathway inhibition was also explored. The effects of NT1014 treatment in vivo was evaluated using the K18 - gT121^+/-; p53^fl/fl; Brca1^fl/fl (KpB) mouse model of high-grade serous ovarian cancer.

RESULTS

NT1014 significantly inhibited cell proliferation in both ovarian cancer cell lines as well as in primary cultures. In addition, NT1014 activated AMPK, inhibited downstream targets of the mTOR pathway, induced G1 cell cycle arrest/apoptosis/cellular stress, altered glycolysis, and reduced invasion/adhesion. Similar to its anti-tumorigenic effects in vitro, NT1014 decreased ovarian cancer growth in the KpB mouse model of ovarian cancer. NT1014 appeared to be more potent than metformin in both our in vitro and in vivo studies.

CONCLUSIONS

NT1014 inhibited ovarian cancer cell growth in vitro and in vivo, with greater efficacy than the traditional biguanide, metformin. These results support further development of NT1014 as a useful therapeutic approach for the treatment of ovarian cancer.

Metformin use and gynecological cancers: A novel treatment option emerging from drug repositioning

Metformin exerts antitumor effects mainly through AMP-activated protein kinase [AMPK] activation and phosphatidylinositol 3-kinase [PI3K]-Akt-mammalian target of rapamycin [mTOR] inhibition. This drug leads to activation of the cellular energy-sensing liver kinase B1 [LKB1]/AMPK pathway. LKB1 is implicated as a tumor suppressor gene in molecular pathogenesis of different malignancies. AMPK is a serine/threonine protein kinase that acts as an ultra-sensitive cellular energy sensor maintaining the energy balance within the cell. AMPK activation inhibits mRNA translation and proliferation in cancer cells via down-regulation of PI3K/Akt/mTOR pathway. Moreover, metformin decreases the production of insulin, insulin-like growth factor, inflammatory cytokines and vascular endothelial growth factor, and therefore it exerts anti-mitotic, anti-inflammatory and anti-angiogenetic effects. Recent in vitro and experimental data suggest that metformin electively targets cancer stem cells, and acts together with chemotherapy to block tumor growth in different cancers. Several epidemiological studies and meta-analysis have shown that metformin use is associated with decreased cancer risk and/or reduced cancer mortality for different malignancies. The present review analyzes the recent biological and clinical data suggesting a possible growth-static effect of metformin also in gynecological cancers. The large majority of available clinical data on the anti-cancer potential of metformin are based on observational studies. Therefore long-term phase II-III clinical trials are strongly warranted to further investigate metformin activity in gynecological cancers.

Association of Metformin Use with Outcomes in Advanced Endometrial Cancer Treated with Chemotherapy

There is increasing evidence that metformin, a commonly used treatment for diabetes, might have the potential to be repurposed as an economical and safe cancer therapeutic. The aim of this study was to determine whether stage III-IV or recurrent endometrial cancer patients who are using metformin during treatment with chemotherapy have improved survival. To test this we analyzed a retrospective cohort of subjects at two independent institutions who received chemotherapy for stage III-IV or recurrent endometrial cancer from 1992 to 2011. Diagnosis of diabetes, metformin use, demographics, endometrial cancer clinico-pathologic parameters, and survival duration were abstracted. The primary outcome was overall survival. The final cohort included 349 patients, 31 (8.9%) had diabetes and used metformin, 28 (8.0%) had diabetes but did not use metformin, and 291 (83.4%) did not have diabetes. The results demonstrate that the median overall survival was 45.6 months for patients with diabetes who used metformin compared to 12.5 months for patients with diabetes who did not use metformin and 28.5 months for patients without diabetes (log-rank test comparing the three groups P = 0.006). In a model adjusted for confounders, the difference in survival between the three groups remained statistically significant (P = 0.023). The improvement in survival among metformin users was not explained by better baseline health status or more aggressive use of chemotherapy. Overall, the findings in this retrospective cohort of endometrial cancer patients with stage III-IV or recurrent disease treated with chemotherapy indicate that patients with diabetes who were concurrently treated with metformin survived longer than patients with diabetes who did not use metformin.

The Impact of Diabetes on Gynecologic Cancer: Current Status and Future Directions

Diabetes mellitus has reached epidemic proportions in both the United States and worldwide with most authorities reporting a doubling in the prevalence of diabetes over the last 20-30 years. While this epidemic is closely tied to obesity, diabetes mellitus presents potential clinical challenges over and above that observed with obesity alone. From a women's health care prospective, this rise in diabetes may impact a woman's health across her lifespan. More specifically, diabetes impacts not only pregnancy as well as well as other medical conditions, but increases the risk for the development of various malignancies. From a gynecologic cancer standpoint, diabetes is most closely associated with endometrial adenocarcinomas, although increasing attention is being placed upon diabetes and ovarian cancer. Attention is also being placed on the potential role of metformin and its impact on outcomes in diabetics with cancer, as well as a potential preventative and/or adjunctive therapy for gynecologic cancer.

Repurposing of phentolamine as a potential anticancer agent against human castration-resistant prostate cancer: A central role on microtubule stabilization and mitochondrial apoptosis pathway

BACKGROUND

Drug repurposing of phentolamine, an α-adrenoceptor antagonist, as an anticancer agent has been studied in human castration-resistant prostate cancer (CRPC).

METHODS

Cell proliferation was examined by sulforhodamine B and CFSE staining assays. Cell cycle progression and mitochondrial membrane potential (ΔΨm) were detected by flow cytometric analysis. Protein expression was detected by Western blotting. Effect on tubulin/microtubule was determined using confocal immunofluorescence microscopic examination, microtubule assembly detection, tubulin turbidity assay, and binding assay. Several assessments were used to characterize apoptotic signaling pathways and combinatory effect.

RESULTS

Phentolamine induced anti-proliferative effect in PC-3 and DU-145, two CRPC cell lines, and P-glycoprotein (P-gp) overexpressing cells. This effect was not significantly reduced in paclitaxel-resistant cells. Rhodamine 123 efflux assay showed that phentolamine was not a P-gp substrate. Phentolamine induced mitotic arrest of the cell cycle and formation of hyperdiploid cells, followed by an increase of apoptosis. Mitotic arrest was confirmed by cyclin B1 up-regulation, Cdk1 activation, and a dramatic increase of mitotic protein phosphorylation. Both in vitro and cellular identification demonstrated that phentolamine, similar to paclitaxel, induced tubulin polymerization and formation of multiple nuclei. Besides, it did not compete with paclitaxel binding on tubulin. Phentolamine induced the phosphorylation and degradation of Bcl-2 and Bcl-xL, two anti-apoptotic Bcl-2 family members, and the loss of ΔΨm indicating the induction of mitochondrial damage. It ultimately induced the activation of caspase-9, -8, and -3 and apoptotic cell death. Moreover, combination treatment with phentolamine and paclitaxel caused a synergistic apoptosis.

CONCLUSIONS

The data suggest that phentolamine is a potential anticancer agent. In contrast to a wide variety of microtubule disrupting agents, phentolamine induces microtubule assembly, leading to mitotic arrest of the cell cycle which "in turn" induces subsequent mitochondrial damage and activation of related apoptotic signaling pathways in CRPC cells. Furthermore, combination between phentolamine and paclitaxel induces a synergistic apoptotic cell death. Phentolamine has a simple chemical structure and is not a P-gp substrate. Optimization of phentolamine structure may also be a potential approach for further development.