Antiproliferative and metabolic effects of metformin in a preoperative window clinical trial for endometrial cancer

Melatonin May Increase Anticancer Potential of Pleiotropic Drugs

Melatonin (N-acetyl-5-methoxytryptamine) is not only a pineal hormone, but also an ubiquitary molecule present in plants and part of our diet. Numerous preclinical and some clinical reports pointed to its multiple beneficial effects including oncostatic properties, and as such, it has become one of the most aspiring goals in cancer prevention/therapy. A link between cancer and inflammation and/or metabolic disorders has been well established and the therapy of these conditions with so-called pleiotropic drugs, which include non-steroidal anti-inflammatory drugs, statins and peroral antidiabetics, modulates a cancer risk too. Adjuvant therapy with melatonin may improve the oncostatic potential of these drugs. Results from preclinical studies are limited though support this hypothesis, which, however, remains to be verified by further research.

Integrated Pharmacodynamic Analysis Identifies Two Metabolic Adaption Pathways to Metformin in Breast Cancer

Late-phase clinical trials investigating metformin as a cancer therapy are underway. However, there remains controversy as to the mode of action of metformin in tumors at clinical doses. We conducted a clinical study integrating measurement of markers of systemic metabolism, dynamic FDG-PET-CT, transcriptomics, and metabolomics at paired time points to profile the bioactivity of metformin in primary breast cancer. We show metformin reduces the levels of mitochondrial metabolites, activates multiple mitochondrial metabolic pathways, and increases 18-FDG flux in tumors. Two tumor groups are identified with distinct metabolic responses, an OXPHOS transcriptional response (OTR) group for which there is an increase in OXPHOS gene transcription and an FDG response group with increased 18-FDG uptake. Increase in proliferation, as measured by a validated proliferation signature, suggested that patients in the OTR group were resistant to metformin treatment. We conclude that mitochondrial response to metformin in primary breast cancer may define anti-tumor effect.

Metformin inhibits ovarian cancer growth and migration in vitro and in vivo by enhancing cisplatin cytotoxicity

The purpose of the current study was to investigate whether metformin can enhance the anti-cancer effect of cisplatin on epithelial ovarian cancer in vitro and in vivo. CCK-8 assays were performed to detect cell viability, and flow cytometry was performed to measure cell apoptosis rates. Transwell assays were used to detect the migration and invasion ability of ovarian cancer cells. Western blotting and qRT-PCR were performed to detect protein expression. Xenograft mouse models were constructed to clarify the treatment response in vivo. Metformin alone or cisplatin alone dose-dependently inhibited SKOV3 and Hey cell proliferation. The combination of these two drugs exerted a stronger inhibitory effect with a higher apoptosis rate than administration of either drug alone. Transwell assay results revealed that metformin promoted the inhibitory effect of cisplatin on ovarian cancer cell metastasis. Metformin and cisplatin co-treatment significantly inhibited N-cadherin and MMP-9 expression. The Western blotting results revealed that metformin and cisplatin co-treatment inhibited TGFβ1 expression and Smad2 and Smad3 phosphorylation. The in vivo study results were consistent with results from the in vitro study. Data from our study suggest that metformin enhanced the anti-tumour effect of cisplatin on epithelial ovarian cancer in vitro and in vivo, which provides more evidence supporting the use of metformin to treat epithelial ovarian cancer.

Pleiotropic Effects of Metformin on Cancer

Metformin (MTF) is a natural compound derived from the legume Galega officinalis. It is the first line antidiabetic drug for type 2 diabetes (T2D) treatment. One of its main antidiabetic effects results from the reduction of hepatic glucose release. First scientific evidence for the anticancer effects of MTF was found in animal research, published in 2001, and some years later a retrospective observational study provided evidence that linked MTF to reduced cancer risk in T2D patients. Its pleiotropic anticancer effects were studied in numerous in vitro and in vivo studies at the molecular and cellular level. Although the majority of these studies demonstrated that MTF is associated with certain anticancer properties, clinical studies and trials provided a mixed view on its beneficial anticancer effects. This review emphasizes the pleiotropic effects of MTF and recent progress made in MTF applications in basic, preclinical, and clinical cancer research.

Metformin as a Therapeutic Target in Endometrial Cancers

Endometrial cancer is the most common gynecologic malignancy in developed countries. Its increasing incidence is thought to be related in part to the rise of metabolic syndrome, which has been shown to be a risk factor for the development of hyperestrogenic and hyperinsulinemic states. This has consequently lead to an increase in other hormone-responsive cancers as well e.g., breast and ovarian cancer. The correlation between obesity, hyperglycemia, and endometrial cancer has highlighted the important role of metabolism in cancer establishment and persistence. Tumor-mediated reprogramming of the microenvironment and macroenvironment can range from induction of cytokines and growth factors to stimulation of surrounding stromal cells to produce energy-rich catabolites, fueling the growth, and survival of cancer cells. Such mechanisms raise the prospect of the metabolic microenvironment itself as a viable target for treatment of malignancies. Metformin is a biguanide drug that is a first-line treatment for type 2 diabetes that has beneficial effects on various markers of the metabolic syndrome. Many studies suggest that metformin shows potential as an adjuvant treatment for uterine and other cancers. Here, we review the evidence for metformin as a treatment for cancers of the endometrium. We discuss the available clinical data and the molecular mechanisms by which it may exert its effects, with a focus on how it may alter the tumor microenvironment. The pleiotropic effects of metformin on cellular energy production and usage as well as intercellular and hormone-based interactions make it a promising candidate for reprogramming of the cancer ecosystem. This, along with other treatments aimed at targeting tumor metabolic pathways, may lead to novel treatment strategies for endometrial cancer.

Metformin as an Anticancer Agent

Metformin has been a frontline therapy for type 2 diabetes (T2D) for many years. Its effectiveness in T2D treatment is mostly attributed to its suppression of hepatic gluconeogenesis; however, the mechanistic aspects of metformin action remain elusive. In addition to its glucose-lowering effect, metformin possesses other pleiotropic health-promoting effects that include reduced cancer risk and tumorigenesis. Metformin inhibits the electron transport chain (ETC) and ATP synthesis; however, recent data reveal that metformin regulates AMP-activated protein kinase (AMPK) and the mechanistic target of rapamycin complex 1 (mTORC1) by multiple, mutually nonexclusive mechanisms that do not necessarily depend on the inhibition of ETC and the cellular ATP level. In this review, we discuss recent advances in elucidating the molecular mechanisms that are relevant for metformin use in cancer treatment.

Management Strategies for Recurrent Endometrial Cancer

INTRODUCTION

Endometrial cancer is the most common gynecologic malignancy in the developed world, and its incidence is increasing. Mortality from this cancer has not improved in recent decades and is primarily driven by high-grade carcinomas that are more likely to present at an advanced stage and ultimately are more likely to recur. The prognosis for recurrent endometrial cancer is poor, especially for the 50% of these women that present with extrapelvic disease recurrence. As a standard of care, recurrent disease has been treated with platinum-based chemotherapy; however, new therapies are emerging as we identify drivers of proliferation and metastasis at the cellular and molecular levels. Areas Covered: We review currently available data for the management of recurrent endometrial cancer, with a focus on systemic treatment of recurrent disease. We discuss the available evidence for first-line, second-line, and subsequent systemic therapy and discuss emerging therapeutic targets including their biologic plausibility and early clinical data. Expert Commentary: Endometrial cancer, though prevalent, remains underfunded and understudied. Recurrent and metastatic disease remains difficult to treat, and prospective randomized data are limited. Our ability to reduce mortality due to this cancer is dependent on identifying new and effective therapeutic strategies for recurrent disease.

Expression of miR-106 in endometrial carcinoma RL95-2 cells and effect on proliferation and invasion of cancer cells

Expression of miR-106 in endometrial carcinoma RL95-2 cell line and its effect on proliferation and invasion of cancer cells was investigated. miR-106 expression vector was constructed and transiently transfected into in vitro cultured RL95-2 cells of human endometrial carcinoma. Cells were divided into three groups including blank control cells (MOCK group), miR-106 transfection group (miR-106 group) and negative control group (siNC group). Reverse-transcription quantitative PCR (RT-qPCR) was used to detect the expression of miR-106. Proliferation and in vitro migration of RL95-2 cells were detected by MTT and scratch assay, and cell apoptosis was detected by flow cytometry. Compared with MOCK and siNC group, cell apoptosis rate was significantly decreased but cell proliferation rate was significantly increased in miR-106 group (p<0.05). In addition, cell migration and invasion ability was significantly increased in miR-106 group (p<0.05). Overexpression of miR-106 can promote proliferation and inhibit apoptosis of endometrial cancer RL95-2 cells, and miR-106 may serve as a new target for the treatment of endometrial cancer in the future.

A Predictor of Tumor Recurrence in Patients With Endometrial Carcinoma After Complete Resection of the Tumor: The Role of Pretreatment Apparent Diffusion Coefficient

Objectives

The aim of this study was to assess the prognostic and incremental value of pretreatment apparent diffusion coefficient (ADC) values of tumors for the prediction of tumor recurrence after complete resection of the tumor in patients with endometrial cancer.

Methods

This study enrolled 210 patients with stages IA to IIIC endometrial cancer who had undergone complete resection of the tumor and pretreatment magnetic resonance imaging. The minimum and mean ADC values (ADCmin, ADCmean) of tumors and normalized ADC (nADCmin, nADCmean) were calculated from magnetic resonance imaging. The primary outcome was recurrence-free survival (RFS). Receiver operating characteristic analysis was performed to compare the diagnostic performance of ADC values of 4 types. The Kaplan-Meier method, log-rank tests, and Cox regression were used to explore associations between recurrence and the ADC values with adjustment for clinicopathological factors.

Results

In receiver operating characteristic curve analysis, the areas under the curve were significant for ADCmean and nADCmean predicting tumor recurrence but were not significant for ADCmin and nADCmin. Regarding univariate analysis, ADCmean and nADCmean were significantly associated with increased risk of recurrence. Multivariate analysis showed that ADCmean and nADCmean remained independently associated with shorter RFS. In the high-risk group, the RFS of patients with lower ADC values (ADCmean and nADCmean) was significantly shorter than that of patients in the higher ADC value group.

Conclusions

Pretreatment tumor ADCmean and nADCmean were important imaging biomarkers for predicting recurrence in patients after complete resection of the tumor. They might improve existing risk stratification.

Effects of Metformin on Cellular Proliferation and Steroid Hormone Receptors in Patient-Derived, Low-Grade Endometrial Cancer Cell Lines

Endometrial cancer (EC) is the most common gynecologic malignancy and is the result of disruption of the balance between estrogen-stimulated growth and progesterone-induced growth modulation. Metformin has been shown to inhibit EC proliferation; however, its role in early-stage EC and its effects on steroid hormone receptors have not been adequately explored. Our aim was to examine the effects of metformin on cellular proliferation in patient-derived, low-grade EC cell lines and to determine whether it directly modulates steroid hormone receptor expression. Two novel EC cell lines were produced (EM2 and 3) from endometrial tumor tissue obtained from women undergoing surgery. Cellular proliferation was determined by the 3-(4,5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide assay, and in both cell lines, metformin decreased cell proliferation in a dose-dependent (10-200 µmol/L) manner and induced apoptosis as measured by cleaved PARP. Furthermore, metformin abrogated the effects of E2 on cell proliferation. Using quantitative real-time polymerase chain reaction and Western immunoblotting, metformin significantly decreased estrogen receptor (ER) α messenger RNA abundance but did not consistently affect the expression of progesterone receptor. Estrogen receptor α protein levels significantly decreased across all metformin doses tested, which resulted in a significant decrease in the expression of the ER targets genes Keratin-19 and Wnt-1 inducible signaling pathway 2. In addition, metformin increased phosphorylation of AMPK in a dose-dependent manner (10-200 µmol/L) indicating an effect on mammalian target of rapamycin (mTOR) signaling. Our data suggest that metformin therapy represents a potential fertility-sparing option for women with early-stage EC, given its capacity to inhibit EC cell proliferation, ERα expression, and the mTOR cell proliferation pathway.

Metformin is associated with reduced cell proliferation in human endometrial cancer by inbibiting PI3K/AKT/mTOR signaling

Metformin recently gained traction as potential anti-endometrial cancer agent for its new applications. However, the underlying mechanisms of the anti-cancer effect of metformin in the endometrial cancer have not yet been fully elucidated. Sixty-five patients diagnosed as endometrial carcinoma were grouped into (n = 33) and non-treatment mixed (n = 32) for analysis. Thirty healthy donors were recruited as controls. We attempt to investigate the effect of metformin on Ki-67, PI3K, p-AKT, p-S6K1, and p-4EBP1 staining in human endometrial cancer by immunohistochemical staining. We found that increased Ki-67 expression in women with endometrial cancer, which were reversed by conventional anti-diabetic doses of metformin in present work. In parallel, the reduced PI3K, p-AKT, p-S6K1, and p-4EBP1 staining induced by metformin appeared to play an important role for the anti-proliferative effects of metformin in endometrial cancer patients. Metformin significantly decreased proliferation in human endometrial cancer may by inhibiting PI3K/AKT/mTOR signaling. Our present results add to the growing body of evidence supporting metformin as a potential anti-cancer agent in endometrial cancer.

Effect of metformin use on the risk and prognosis of endometrial cancer: a systematic review and meta-analysis

BACKGROUND

Previous studies have suggested that metformin may be useful for preventing and treating endometrial cancer (EC), while the results have been inconsistent. This systematic review and meta-analysis aimed to investigate the association between metformin use and risk and prognosis of patients with EC.

METHODS

PubMed, Embase, and the Cochrane Library databases were searched for observational studies evaluating the effect of metformin on EC prevention or treatment. The odds ratio (OR) was used for analyzing risks, and the hazard ratio (HR) was used for analyzing survival outcomes. A random-effects model was used for data analysis.

RESULTS

Seven studies reported data on EC risk. The pooled results suggested that metformin was not significantly associated with a lower risk of EC [OR = 1.05, 95% confidence interval (CI) 0.82-1.35, P = 0.70]. For patients with diabetes, metformin showed no advantage in reducing the EC risk compared with other interventions (OR = 0.99, 95% CI 0.78-1.26, P = 0.95). Further, seven studies were included for survival analysis. The pooled data showed that metformin could significantly improve the overall survival of patients with EC (HR = 0.61, 95% CI 0.48-0.77, P < 0.05) and reduce the risk of EC recurrence (OR = 0.50, 95% CI 0.28-0.92, P < 0.05) Finally, we noted metformin was associated with significantly improving the overall survival of EC patients among diabetes (HR = 0.47; 95%CI 0.33-0.67, P < 0.05).

CONCLUSIONS

This meta-analysis did not prove that metformin was beneficial for preventing EC. However, metformin could prolong the overall survival of patients with EC and reduce their risk of cancer relapse.

Moving forward with actionable therapeutic targets and opportunities in endometrial cancer: A NCI clinical trials planning meeting report

The incidence of endometrial cancer (EC) in the U.S. has been rising, from an estimated annual incidence of 49,560 in 2013 to 61,380 in 2017. Meanwhile, the SEER-based relative survival of women with EC in the U.S. has remained flat [82.3% from 1987 to 1989, 82.8% from 2007 to 2013] and our recent increased understanding of EC biology and subtypes has not been translated into therapeutic advances. The U.S. National Cancer Institute (NCI) therefore convened a Uterine Clinical Trials Planning Meeting in January 2016 to initiate and accelerate design of molecularly-targeted EC trials. Prior to the meeting a group of experts in this field summarized available data, emphasizing data on human samples, to identify potentially actionable alterations in EC, and the results of their work has been separately published. The Clinical Trials Meeting planners focused on discussion of (1) novel trial designs, including window-of opportunity trials and appropriate control groups for randomized trials, (2) targets specific to serous carcinoma and promises and pitfalls of separate trials for women with tumors of this histology (3) specific recommendations for future randomized trials.

On metabolic reprogramming and tumor biology: A comprehensive survey of metabolism in breast cancer

Altered metabolism in tumor cells has been a focus of cancer research for as long as a century but has remained controversial and vague due to an inhomogeneous overall picture. Accumulating genomic, metabolomic, and lastly panomic data as well as bioenergetics studies of the past few years enable a more comprehensive, systems-biologic approach promoting deeper insight into tumor biology and challenging hitherto existing models of cancer bioenergetics. Presenting a compendium on breast cancer-specific metabolome analyses performed thus far, we review and compile currently known aspects of breast cancer biology into a comprehensive network, elucidating previously dissonant issues of cancer metabolism. As such, some of the aspects critically discussed in this review include the dynamic interplay or metabolic coupling between cancer (stem) cells and cancer-associated fibroblasts, the intratumoral and intertumoral heterogeneity and plasticity of cancer cell metabolism, the existence of distinct metabolic tumor compartments in need of separate yet simultaneous therapeutic targeting, the reliance of cancer cells on oxidative metabolism and mitochondrial power, and the role of pro-inflammatory, pro-tumorigenic stromal conditioning. Comprising complex breast cancer signaling networks as well as combined metabolomic and genomic data, we address metabolic consequences of mutations in tumor suppressor genes and evaluate their contribution to breast cancer predisposition in a germline setting, reasoning for distinct personalized preventive and therapeutic measures. The review closes with a discussion on central root mechanisms of tumor cell metabolism and rate-limiting steps thereof, introducing essential strategies for therapeutic targeting.

The expanding role of metformin in cancer: an update on antitumor mechanisms and clinical development

Metformin has been used for nearly a century to treat type 2 diabetes mellitus. Epidemiologic studies first identified the association between metformin and reduced risk of several cancers. The anticancer mechanisms of metformin involve both indirect or insulin-dependent pathways and direct or insulin-independent pathways. Preclinical studies have demonstrated metformin's broad anticancer activity across a spectrum of malignancies. Prospective clinical trials involving metformin in the chemoprevention and treatment of cancer now number in the hundreds. We provide an update on the anticancer mechanisms of metformin and review the results thus far available from prospective clinical trials investigating metformin's efficacy in cancer.

Moving forward with actionable therapeutic targets and opportunities in endometrial cancer: NCI clinical trials planning meeting report on identifying key genes and molecular pathways for targeted endometrial cancer trials

The incidence and mortality rates from endometrial cancer are increasing. There have been no new drugs approved for the treatment of endometrial cancer in decades. The National Cancer Institute, Gynecologic Cancer Steering Committee identified the integration of molecular and/or histologic stratification into endometrial cancer management as a top strategic priority. Based on this, they convened a group of experts to review the molecular data in this disease. Here we report on the actionable opportunities and therapeutic directions identified for incorporation into future clinical trials.

Applications of Metabolomics in Cancer Studies

Since the start of metabolomics as a field of research, the number of studies related to cancer has grown to such an extent that cancer metabolomics now represents its own discipline. In this chapter, the applications of metabolomics in cancer studies are explored. Different approaches and analytical platforms can be employed for the analysis of samples depending on the goal of the study and the aspects of the cancer metabolome being investigated. Analyses have concerned a range of cancers including lung, colorectal, bladder, breast, gastric, oesophageal and thyroid, amongst others. Developments in these strategies and methodologies that have been applied are discussed, in addition to exemplifying the use of cancer metabolomics in the discovery of biomarkers and in the assessment of therapy (both pharmaceutical and nutraceutical). Finally, the application of cancer metabolomics in personalised medicine is presented.

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.

Repurposing metformin for the prevention of cancer and cancer recurrence

Multiple epidemiological studies have documented an association between metformin, used for treatment of type 2 diabetes, and reduced cancer incidence and mortality. Cell line models may not accurately reflect the effects of metformin in the clinical setting. Moreover, findings from animal model studies have been inconsistent, whilst those from more recent epidemiological studies have tempered the overall effect size. The purpose of this review is to examine metformin's chemopreventive potential by outlining relevant mechanisms of action, the most recent epidemiologic evidence, and recently completed and ongoing clinical trials. Although repurposing drugs with excellent safety profiles is an appealing strategy for cancer prevention and treatment in the adjuvant setting, there is no substitute for well-executed, large randomised clinical trials to define efficacy and determine the populations that are most likely to benefit from an intervention. Thus, enthusiasm remains for understanding the role of metformin in cancer through ongoing clinical research.

Effects of metformin on endometrial cancer: Systematic review and meta-analysis

BACKGROUND

Endometrial cancer is one of the most common gynecological cancers, which is frequently preceded by atypical endometrial hyperplasia, a premalignant lesion. Metformin, an antidiabetic drug, has emerged as a new adjunctive strategy for different cancer types, including endometrial cancer. This systematic review and meta-analysis aimed to evaluate the effects of metformin in atypical endometrial hyperplasia and endometrial cancer patients.

METHODS

The search was conducted on January 2017 and the articles were collected in Cochrane, LILACS, PubMed, Scopus and Web of Science. A grey literature search was undertaken using Google SCHOLAR, ProQuest and Open Grey. Nineteen studies were included, which contained information about the following outcomes: reversal of atypical endometrial hyperplasia, cellular proliferation biomarkers expression and overall survival in metformin-users compared to non-users.

RESULTS

Metformin was associated with reversion of atypical endometrial hyperplasia to a normal endometrial, and with decreased cell proliferation biomarkers staining, from 51.94% (CI=36.23% to 67.46%) to 34.47% (CI=18.55% to 52.43%). However, there is a high heterogeneity among studies. Metformin-users endometrial cancer patients had a higher overall survival compared to non-metformin users and non-diabetic patients (HR=0.82; CI: 0.70-0.95; p=0.09, I²=40%).

CONCLUSION

Regardless the high heterogeneity of the analyzed studies, the present review suggests that adjunct metformin treatment may assist in the reversal of atypical endometrial hyperplasia to normal endometrial histology, in the reduction of cell proliferation biomarkers implicated in tumor progression, and in the improvement of overall survival in endometrial cancer. Further work on prospective controlled trials designed to address the effects of adjunct metformin on clinical outcomes is necessary for definite conclusions.

Metformin and breast cancer stage at diagnosis: a population-based study

PURPOSE

The objective of the present study was to use a large, population-based cohort to examine the association between metformin and breast cancer stage at diagnosis while accounting for mammography differences.

METHODS

We used data from Ontario administrative health databases to identify women 68 years of age or older with diabetes and invasive breast cancer diagnosed from 1 January 2007 to 31 December 2012. Adjusted logistic regression models were used to compare breast cancer stage at diagnosis (stages i and ii vs. iii and iv) between the women exposed and not exposed to metformin. We also examined the association between metformin use and estrogen receptor status, tumour size, and lymph node status in the subset of women for whom those data were available.

RESULTS

We identified 3125 women with diabetes and breast cancer; 1519 (48.6%) had been exposed to metformin before their cancer diagnosis. Median age at breast cancer diagnosis was 76 years (interquartile range: 72-82 years), and mean duration of diabetes was 8.8 ± 5.9 years. In multivariable analyses, metformin exposure was not associated with an earlier stage of breast cancer (odds ratio: 0.98; 95% confidence interval: 0.81 to 1.19). In secondary analyses, metformin exposure was not associated with estrogen receptor-positive breast cancer, tumours larger than 2 cm, or positive lymph nodes.

CONCLUSIONS

This population-based study did not show an association between metformin use and breast cancer stage or tumour characteristics at diagnosis. Our study considered older women with long-standing diabetes, and therefore further studies in younger patients could be warranted.

Ki-67 in endometrial cancer: scoring optimization and prognostic relevance for window studies

Ki-67, a marker of cellular proliferation, is increasingly being used in pre-surgical window studies in endometrial cancer as a primary outcome measure. Unlike in breast cancer, however, there are no guidelines standardizing its measurement and its clinical relevance as a response biomarker is undetermined. It is, therefore, imperative that Ki-67 scoring protocols are optimized and its association with patient survival rigorously evaluated, in order to be able to clinically interpret the results of these studies. Using the International Ki-67 in Breast Cancer Working Group guidelines as a basis, whole slide, hot spot and invasive edge scoring protocols were evaluated using endometrial biopsies and hysterectomy specimens from 179 women. Whole sections and tissue microarrays, manual and semi-automated scoring using Definiens Developer software were additionally compared. Ki-67 scores were related to clinicopathological variables and cancer-specific survival in uni- and multivariate analysis. Against criteria of time efficiency, intra- and inter-observer variability and consistency, semi-automated hot spot scoring was the preferred method. Ki-67 scores positively correlated with grade, stage and depth of myometrial invasion (P-values all <0.03). By univariate analysis, higher Ki-67 scores were associated with a significant reduction in cancer-specific survival (P≤0.05); however, this effect was substantially attenuated in the multivariate model. In conclusion, hot spot scoring of whole sections using Definiens is an optimal method to quantify Ki-67 in endometrial cancer window study specimens. Measured this way, it is a clinically relevant marker, though further work is required to determine whether reductions in Ki-67 in neoadjuvant intervention studies translate into improved patient outcome.

Receptor for advanced glycation end as drug targets in diabetes-induced skin lesion

The involvement of the receptor for advanced glycation end (RAGE) in different diseases has been reviewed in great detail, previously, but the effects of diabetic drugs on RAGE-induced skin lesion during long course diabetes remains poorly understood. In the present study, we have shown that RAGE was overexpressed in both diabetic rats and human keratinocytes (HaCaT cells). Cell cycle arrest and apoptosis as well as alternations of relative protein levels were also found in diabetic rats and HaCaT cells with overexpression of RAGE that were rectified by metformin (Met) treatment. Moreover, overexpression of RAGE was also found to induce secretions of TNF-α, IL-1β, IL-6, ICAM-1 and COX-2 in HaCaT cells, and Met treatment corrected these inflammatory factor secretions. In addition, treatment with Met markedly reduced RAGE overexpression-induced p38 and NF-κB activation. Taken together, the findings of the present study have demonstrated, for the first time that Met protects HaCaT cells against diabetes-induced injuries and inflammatory responses through inhibiting activated RAGE.

Pancreatic cancer actionable genes in precision medicine and personalized surgery

Pancreatic ductal adenocarcinoma (PDAC) is a deadly cancer with an overall 5-year survival rate less than 5% due to the poor early diagnosis and lack of effective therapeutic options. The most effective therapy remains surgery, however post-operative survival could be enhanced with effective adjuvant therapy. The massive information gained from Omics techniques on PDAC at the beginning of the 21st century is a remarkable accomplishment. However, the information gained from the omics data, including next generation sequencing data, has yet to successfully affect care of patients suffering with PDAC. Therefore, we propose the development of an actionable genomic platform that matches a patient's PDAC clinically actionable genes with potential targeted adjuvant therapies. Using this platform, PDX1 has been identified as a potential actionable gene for PDAC, therefore, RNAi therapy, gene therapy and small inhibitory drugs, all targeting PDX1, serve as potential targeted adjuvant therapies. Preclinical studies support the hypothesis that identification of PDAC actionable genes could permit translation of a patient's genomic information into precision targeted adjuvant therapy for PDAC.

Prospective evaluation of abnormal glucose metabolism and insulin resistance in patients with atypical endometrial hyperplasia and endometrial cancer

PURPOSE

Obesity and diabetes (DM) are known to increase the risk of endometrial cancer (EC). However, little is known about the prevalence of abnormal glucose metabolism and insulin resistance (IR) in EC patients. We aimed to evaluate the prevalence of abnormal glucose metabolism and IR in EC patients.

METHODS

We prospectively enrolled atypical endometrial hyperplasia (AEH) and EC patients who had received planned treatment at Chiba University Hospital, Japan. All patients, except those with a confirmed diagnosis of DM, underwent the 75-g oral glucose tolerance test (OGTT) before treatment. We evaluated the prevalence of obesity, defined as body mass index (BMI) ≥25, IR, abnormal glucose metabolism, and the associations between these three factors and the clinical characteristics of AEH and EC patients.

RESULTS

We enrolled 279 patients from April 2009 to March 2015. Of these, 56 had a confirmed diagnosis of DM. Abnormal OGTT results, including impaired fasting glucose (n = 7), impaired glucose tolerance (n = 69), and newly identified DM (n = 33), were noted in 109 patients. Obesity, IR, and abnormal glucose metabolism were observed in 49.8, 51.6, and 59.1% of patients, respectively. Abnormal glucose metabolism was significantly associated with age (P < 0.001), body mass index (P = 0.004), and IR status (P < 0.001) in multivariate analysis.

CONCLUSION

Abnormal glucose metabolism, IR, and obesity were highly prevalent in patients with AEH and EC. These results indicate that physicians should consider a patient's metabolic status in the postoperative management of AEH and EC patients.

A story of metformin-butyrate synergism to control various pathological conditions as a consequence of gut microbiome modification: Genesis of a wonder drug?

The most widely prescribed oral anti-diabetic agent today in the world today is a member of the biguanide class of drugs called metformin. Apart from its use in diabetes, it is currently being investigated for its potential use in many diseases such as cancer, cardiovascular diseases, Alzheimer's disease, obesity, comorbidities of diabetes such as retinopathy, nephropathy to name a few. Numerous in-vitro and in-vivo studies as well as clinical trials have been and are being conducted with a vast amount of literature being published every day. Numerous mechanisms for this drug have been proposed, but they have been unable to explain all the actions observed clinically. It is of interest that insulin has a stimulatory effect on cellular growth. Metformin sensitizes the insulin action but believed to be beneficial in cancer. Like -wise metformin is shown to have beneficial effects in opposite sets of pathological scenario looking from insulin sensitization point of view. This requires a comprehensive review of the disease conditions which are claimed to be affected by metformin therapy. Such a comprehensive review is presently lacking. In this review, we begin by examining the history of metformin before it became the most popular anti-diabetic medication today followed by a review of its relevant molecular mechanisms and important clinical trials in all areas where metformin has been studied and investigated till today. We also review novel mechanistic insight in metformin action in relation to microbiome and elaborate implications of such aspect in various disease states. Finally, we highlight the quandaries and suggest potential solutions which will help the researchers and physicians to channel their research and put this drug to better use.

Prospective evaluation of the molecular effects of metformin on the endometrium in women with newly diagnosed endometrial cancer: A window of opportunity study

OBJECTIVE

Metformin reduces cancer incidence and improves overall survival in diabetic patients. In preclinical studies, metformin decreases endometrial cancer (EC) cell growth by activation of AMPK/mTOR inhibition. We sought to determine the effects of metformin on serum/tumor biomarkers in women with EC.

METHODS

In this prospective trial, newly diagnosed EC patients underwent pre-treatment blood draw/endometrial biopsy, were administered oral metformin 850mg daily for ≥7days, and underwent post-treatment blood draw/definitive surgery. Pre- and post- serum analyses were performed. Tumor samples were evaluated for changes in AMPK, PI3K/AKT pathway, proliferation, and apoptosis by immunohistochemistry.

RESULTS

Twenty patients completed the trial. Median age and BMI were 57years (range: 27-67) and 34.5kg/m2 (range: 21.9-50.0). Median duration of metformin was 9.5days (range: 7-24). A majority of women had endometrioid adenocarcinomas (90%) and were early stage (85%). After metformin, there were significant decreases in serum IGF-1 (p=0.046), omentin (p=0.007), insulin (p=0.012), C-peptide (p=0.018), and leptin (p=0.0035). Compared to baseline, post-treatment tissue showed decreased phospho-AKT in 18/20 patients (90%, p=0.0002), decreased phospho-S6rp in 14/20 patients (70%, p=0.057), and decreased phospho-p44/42MAPK in 15/18 patients (83.3%, p=0.0038). There was no difference in Ki67, phospho-ACC, or caspase 3. Changes did not correlate with BMI, grade, or KRAS mutation.

CONCLUSION

In this prospective window of opportunity study, we demonstrated that relevant serum and molecular changes occur in patients with newly diagnosed EC after a short course of metformin. Ongoing clinical trials will help determine the appropriate role for metformin in the treatment of women with EC.

Syrosingopine sensitizes cancer cells to killing by metformin

We report that the anticancer activity of the widely used diabetic drug metformin is strongly potentiated by syrosingopine. Synthetic lethality elicited by combining the two drugs is synergistic and specific to transformed cells. This effect is unrelated to syrosingopine's known role as an inhibitor of the vesicular monoamine transporters. Syrosingopine binds to the glycolytic enzyme α-enolase in vitro, and the expression of the γ-enolase isoform correlates with nonresponsiveness to the drug combination. Syrosingopine sensitized cancer cells to metformin and its more potent derivative phenformin far below the individual toxic threshold of each compound. Thus, combining syrosingopine and codrugs is a promising therapeutic strategy for clinical application for the treatment of cancer.

Targeting Cancer Metabolism: Dietary and Pharmacologic Interventions

Most tumors display oncogene-driven reprogramming of several metabolic pathways, which are crucial to sustain their growth and proliferation. In recent years, both dietary and pharmacologic approaches that target deregulated tumor metabolism are beginning to be considered for clinical applications. Dietary interventions exploit the ability of nutrient-restricted conditions to exert broad biological effects, protecting normal cells, organs, and systems, while sensitizing a wide variety of cancer cells to cytotoxic therapies. On the other hand, drugs targeting enzymes or metabolites of crucial metabolic pathways can be highly specific and effective, but must be matched with a responsive tumor, which might rapidly adapt. In this review, we illustrate how dietary and pharmacologic therapies differ in their effect on tumor growth, proliferation, and metabolism and discuss the available preclinical and clinical evidence in favor of or against each of them. We also indicate, when appropriate, how to optimize future investigations on metabolic therapies on the basis of tumor- and patient-related characteristics.

SIGNIFICANCE

To our knowledge, this is the first review article that comprehensively analyzes the preclinical and preliminary clinical experimental foundations of both dietary and pharmacologic metabolic interventions in cancer therapy. Among several promising therapies, we propose treatment personalization on the basis of tumor genetics, tumor metabolism, and patient systemic metabolism.Cancer Discov; 6(12); 1315-33. ©2016 AACR.

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.

Metformin displays in vitro and in vivo antitumor effect against osteosarcoma

Purpose

Patients with unresectable, relapsed, or refractory osteosarcoma need a novel therapeutic agent. Metformin is a biguanide derivative used in the treatment of type II diabetes, and is recently gaining attention in cancer research.

Methods

We evaluated the effect of metformin against human osteosarcoma. Four osteosarcoma cell lines (KHOS/NP, HOS, MG-63, U-2 OS) were treated with metformin and cell proliferation was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cell cycle progression and apoptosis were evaluated using flow cytometric analysis, and migration and wound healing assay were performed. Fourteen female Balb/c-nude mice received KHOS/NP cell grafts in their thigh, and were allowed access to metformin containing water (2 mg/mL) ad libitum. Tumor volume was measured every 3–4 days for a period of 4 weeks.

Results

Metformin had a significant antiproliferative effect on human osteosarcoma cells. In particular, metformin inhibited the proliferation and migration of KHOS/NP cells by activation of AMP-activated protein kinase and consequent inhibition of the mammalian target of rapamycin pathway. It also inhibited the proliferation of cisplatin-resistant KHOS/NP clone cells. Analysis of KHOS/NP xenograft Balb/c-nude models indicated that metformin displayed potent in vivo antitumor effects.

Conclusion

Further studies are necessary to explore metformin's therapeutic potential and the possibilities for its use as an adjuvant agent for osteosarcoma.

Monitoring cancer prognosis, diagnosis and treatment efficacy using metabolomics and lipidomics

INTRODUCTION

Cellular metabolism is altered during cancer initiation and progression, which allows cancer cells to increase anabolic synthesis, avoid apoptosis and adapt to low nutrient and oxygen availability. The metabolic nature of cancer enables patient cancer status to be monitored by metabolomics and lipidomics. Additionally, monitoring metabolic status of patients or biological models can be used to greater understand the action of anticancer therapeutics.

OBJECTIVES

Discuss how metabolomics and lipidomics can be used to (i) identify metabolic biomarkers of cancer and (ii) understand the mechanism-of-action of anticancer therapies. Discuss considerations that can maximize the clinical value of metabolic cancer biomarkers including case-control, prognostic and longitudinal study designs.

METHODS

A literature search of the current relevant primary research was performed.

RESULTS

Metabolomics and lipidomics can identify metabolic signatures that associate with cancer diagnosis, prognosis and disease progression. Discriminatory metabolites were most commonly linked to lipid or energy metabolism. Case-control studies outnumbered prognostic and longitudinal approaches. Prognostic studies were able to correlate metabolic features with future cancer risk, whereas longitudinal studies were most effective for studying cancer progression. Metabolomics and lipidomics can help to understand the mechanism-of-action of anticancer therapeutics and mechanisms of drug resistance.

CONCLUSION

Metabolomics and lipidomics can be used to identify biomarkers associated with cancer and to better understand anticancer therapies.

The prognostic role of metformin in patients with endometrial cancer: a retrospective study

OBJECTIVE

Metformin has recently been discussed to possess anticancer activities and to positively affect the risk of developing cancer. We performed the present study to investigate the association of metformin and survival in patients with endometrial cancer.

STUDY DESIGN

Within the present study we retrospectively reviewed the records of 465 consecutive patients with endometrial cancer. Drug intake of metformin was correlated with clinico-pathological parameters and the patients' survival. Chi-square test, Kruskal Wallis test, the product limit method of Kaplan and Meier, and multivariable Cox regression models were used to assess associations between metformin and clinico-pathological parameters and survival, as appropriate.

RESULTS

Eighty-seven (18.7%) patients suffered from diabetes and of these 46 (52.8%) used metformin at the time of diagnosis. When analysing all patients, metformin did not affect the patients' survival. However, within the subgroup of overweight patients metformin was associated with a prolongation of overall survival (p=0.04). Within this subgroup, diabetic patients who did not use metformin had a 2.3 times higher risk for death (95%CI 1.1-4.7; p=0.02) compared to non-diabetic patients and diabetic patients using metformin. Metformin was not associated with prolonged recurrence-free or cancer-specific survival, irrespective of the patients' body mass index (p=0.08 and p=0.4, respectively).

CONCLUSION

The results of our study might suggest a beneficial effect of metformin on overall survival in overweight diabetic patients with endometrial cancer. However, the question, if metformin can reduce the risk to die from endometrial cancer or improves all cause mortality only still remains open and needs further investigation.

Repurposing metformin for cancer treatment: current clinical studies

In recent years, several studies have presented evidence suggesting a potential role for metformin in anti-cancer therapy. Preclinical studies have demonstrated several anticancer molecular mechanisms of metformin including mTOR inhibition, cytotoxic effects, and immunomodulation. Epidemiologic data have demonstrated decreased cancer incidence and mortality in patients taking metformin. Several clinical trials, focused on evaluation of metformin as an anti-cancer agent are presently underway. Data published from a small number of completed trials has put forth intriguing results. Clinical trials in pre-surgical endometrial cancer patients exhibited a significant decrease in Ki67 with metformin monotherapy. Another interesting observation was made in patients with breast cancer, wherein a trend towards improvement in cancer proliferation markers was noted in patients without insulin resistance. Data on survival outcomes with the use of metformin as an anti-cancer agent is awaited. This manuscript will critically review the role of metformin as a potential cancer treatment.

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.

Metformin Induces Cell Cycle Arrest, Reduced Proliferation, Wound Healing Impairment In Vivo and Is Associated to Clinical Outcomes in Diabetic Foot Ulcer Patients

Background

Several epidemiological studies in diabetic patients have demonstrated a protective effect of metformin to the development of several types of cancer. The underlying mechanisms of such phenomenon is related to the effect of metformin on cell proliferation among which, mTOR, AMPK and other targets have been identified. However, little is known about the role that metformin treatment have on other cell types such as keratinocytes and whether exposure to metformin of these cells might have serious repercussions in wound healing delay and in the development of complications in diabetic patients with foot ulcers or in their exacerbation.

Material and Methods

HaCaT Cells were exposed to various concentrations of metformin and cell viability was evaluated by a Resazurin assay; Proliferation was also evaluated with a colony formation assay and with CFSE dilution assay by flow cytometry. Cell cycle was also evaluated by flow cytometry by PI staining. An animal model of wound healing was used to evaluate the effect of metformin in wound closure. Also, an analysis of patients receiving metformin treatment was performed to determine the effect of metformin treatment on the outcome and wound area. Statistical analysis was performed on SPSS v. 18 and GraphPad software v.5.

Results

Metformin treatment significantly reduces cell proliferation; colony formation and alterations of the cell cycle are observed also in the metformin treated cells, particularly in the S phase. There is a significant increase in the area of the wound of the metformin treated animals at different time points (P<0.05). There is also a significant increase in the size and wound area of the patients with diabetic foot ulcers at the time of hospitalization. A protective effect of metformin was observed for amputation, probably associated with the anti inflammatory effects reported of metformin.

Conclusions

Metformin treatment reduces cell proliferation and reduces wound healing in an animal model and affects clinical outcomes in diabetic foot ulcer patients. Chronic use of this drug should be further investigated to provide evidence of their security in association with DFU.

Measuring the biological effect of presurgical metformin treatment in endometrial cancer

Background:

Preclinical studies in endometrial cancer (EC) show that metformin reduces cellular proliferation by PI3K-AKT-mTOR inhibition. We tested the hypothesis that short-term presurgical metformin reduces cellular proliferation in atypical endometrial hyperplasia (AEH) and endometrioid EC, and assessed the feasibility of using phosphorylated PI3K-AKT-mTOR proteins as tissue end points.

Methods:

Women with AEH or EC received metformin 850 mg twice a day or no drug in the presurgical window between diagnosis and hysterectomy. Before and after the window, tissue samples were obtained; serum markers of insulin resistance (e.g. homeostasis model of assessment of insulin resistance index) were determined; and anthropometrics measured (e.g. BMI). Cell proliferation (Ki-67) and PI3K-AKT-mTOR phosphostatus were assessed by immunohistochemistry and scored blinded to treatment.

Results:

Twenty-eight metformin-treated and 12 untreated patients, well matched for age and BMI, completed the study. Metformin treatment (median 20 days, range 7–34) was associated with a 17.2% reduction in tumour Ki-67 (95% CI −27.4, −7.0, P=0.002), in a dose-dependent manner. Tumour PI3K-AKT-mTOR protein phosphostatus varied but the effects were not significant after adjusting for changes in controls.

Conclusions:

Short-term metformin was associated with reduced Ki-67 expression in EC. Changes in tumour PI3K-AKT-mTOR protein phosphostatus were seen in both groups. Future studies should address the variability attributed to different sampling techniques including devascularisation of the uterus at hysterectomy.

Phase II study of medroxyprogesterone acetate plus metformin as a fertility-sparing treatment for atypical endometrial hyperplasia and endometrial cancer

BACKGROUND

Metformin, widely used in the treatment of type 2 diabetes mellitus, reduces the risk of cancer and relapse after treatment. Fertility-sparing treatment for endometrial cancer (EC) with progestin is associated with a high chance of disease regression, and the high relapse rate continues to be a problem. We assessed the efficacy of metformin in preventing recurrence after medroxyprogesterone acetate (MPA) as fertility-sparing treatment for atypical endometrial hyperplasia (AEH) and EC.

PATIENTS AND METHODS

This phase II study enrolled 17 patients with AEH and 19 patients with EC limited to the endometrium (age, 20-40 years). MPA (400 mg/day) and metformin (750-2250 mg/day) were administered for 24-36 weeks to achieve a complete response (CR). Metformin was administered until conception, even after MPA discontinuation. The primary end point was relapse-free survival (RFS) after remission. We analyzed all efficacy end points in the full analysis set.

RESULTS

The body mass index was ≥25 kg/m(2) in 27 patients (mean, 31 kg/m(2); range, 19-51 kg/m(2)), and the homeostasis model assessment for insulin resistance index was ≥2.5 in 24 patients (mean, 4.7; range, 0.7-21). Two patients showed progression at 12 weeks [6%; 95% confidence interval (CI) 2-18]. At 36 weeks, 29 (81%; 95% CI 65-90) patients achieved CR, and 5 (14%; 95% CI 6-29) patients achieved partial response. During a median follow-up of 38 months (range, 9-66 months) after remission, relapse was confirmed in three of the patients who had achieved CR (relapse rate, 10%). The 3-year estimated RFS rate was 89%. No patients experienced severe toxicity.

CONCLUSIONS

Metformin inhibited disease relapse after MPA therapy. The combination of metformin and MPA in EC treatment should be studied further.

TRIAL REGISTRATION NUMBER

UMIN 000002210.

Regulation of Androgen Receptor Expression Alters AMPK Phosphorylation in the Endometrium: In Vivo and In Vitro Studies in Women with Polycystic Ovary Syndrome

The failure of reproductive success in polycystic ovary syndrome (PCOS) patients could be in part due to endometrial dysfunction. However, no studies have investigated any causality between androgen, androgen receptor (AR) expression, and adenosine monophosphate activated protein kinase (AMPK) activation in the endometrium under physiological and pathological conditions. In the present study, we show that 1) endometrial AR expression levels fluctuate in non-PCOS and PCOS patients during the menstrual cycle; 2) the menstrual phase-dependent alteration of p-AMPKα expression occurs in non-PCOS patients but not in PCOS patients; 3) AR expression is higher in PCOS patients than non-PCOS patients during hyperplasia while AMPKα activation (indicated by the ratio of p-AMPKα to AMPKα); and 4) co-localization of AR and Ki-67 in epithelial cell nuclei is observed in endometrial hyperplasia. Importantly, using in vitro human tissue culture and an in vivo 5α-dihydrotestosterone-treated rat model, we show that the action of androgen on AMPKα activation is likely mediated through nuclear AR, especially in epithelial cells. Collectively, we present evidence that AR expression and AMPKα activation depend on menstrual cycle phase and the presence of PCOS, and the data suggest that AR-mediated regulation of AMPKα activation might play a role in the development of endometrial hyperplasia.

Development, Maintenance, and Reversal of Multiple Drug Resistance: At the Crossroads of TFPI1, ABC Transporters, and HIF1

Early detection and improved therapies for many cancers are enhancing survival rates. Although many cytotoxic therapies are approved for aggressive or metastatic cancer; response rates are low and acquisition of de novo resistance is virtually universal. For decades; chemotherapeutic treatments for cancer have included anthracyclines such as Doxorubicin (DOX); and its use in aggressive tumors appears to remain a viable option; but drug resistance arises against DOX; as for all other classes of compounds. Our recent work suggests the anticoagulant protein Tissue Factor Pathway Inhibitor 1α (TFPI1α) plays a role in driving the development of multiple drug resistance (MDR); but not maintenance; of the MDR state. Other factors; such as the ABC transporter drug efflux pumps MDR-1/P-gp (ABCB1) and BCRP (ABCG2); are required for MDR maintenance; as well as development. The patient population struggling with therapeutic resistance specifically requires novel treatment options to resensitize these tumor cells to therapy. In this review we discuss the development, maintenance, and reversal of MDR as three distinct phases of cancer biology. Possible means to exploit these stages to reverse MDR will be explored. Early molecular detection of MDR cancers before clinical failure has the potential to offer new approaches to fighting MDR cancer.

Metformin Increases Sensitivity of Pancreatic Cancer Cells to Gemcitabine by Reducing CD133+ Cell Populations and Suppressing ERK/P70S6K Signaling

The prognosis of pancreatic cancer remains dismal, with little advance in chemotherapy because of its high frequency of chemoresistance. Metformin is widely used to treat type II diabetes, and was shown recently to inhibit pancreatic cancer stem cell proliferation. In the present study, we investigated the role of metformin in chemoresistance of pancreatic cancer cells to gemcitabine, and its possible cellular and molecular mechanisms. Metformin increases sensitivity of pancreatic cancer cells to gemcitabine. The mechanism involves, at least in part, the inhibition of CD133⁺ cells proliferation and suppression of P70S6K signaling activation via inhibition of ERK phosphorylation. Studies of primary tumor samples revealed a relationship between P70S6K signaling activation and the malignancy of pancreatic cancer. Analysis of clinical data revealed a trend of the benefit of metformin for pancreatic cancer patients with diabetes. The results suggested that metformin has a potential clinical use in overcoming chemoresistance of pancreatic cancer.

Repurposing old drugs to chemoprevention: the case of metformin

Multiple epidemiologic studies have documented an association between the anti-diabetic agent metformin and reduced cancer incidence and mortality. However, this effect has not been consistently demonstrated in animal models or more recent epidemiological studies. The purpose of this paper is to examine metformin's chemopreventive potential by reviewing relevant mechanisms of action, preclinical evidence of efficacy, updated epidemiologic evidence after correction for potential biases and confounders, and recently completed and ongoing clinical trials. Although repurposing drugs with well described mechanisms of action and safety profiles is an appealing strategy for cancer prevention, there is no substitute for well executed late phase clinical trials to define efficacy and populations that are most likely to benefit from an intervention.

Metformin in breast cancer - an evolving mystery

Metformin, a diabetes drug with well-established side effect and safety profiles, has been widely studied for its anti-tumor activities in a number of cancers, including breast cancer. But its mechanism of action in the clinical arena remains elusive. In a window of opportunity trial of metformin in non-diabetic breast cancer patients, Dowling and colleagues examined both the direct actions of the drug on cancer cells (as mediated by AMP kinase), as well as its indirect actions (as mediated by circulating insulin). The data suggest that short-term administration of metformin in this setting has anti-tumor effects significantly involving the indirect, insulin-dependent pathway. The role of the direct pathway remains to be determined. This study represents an important step forward in establishing one of several possible mechanisms for metformin, information that will be useful in determining candidate biomarkers to evaluate in large clinical trials of metformin, such as the ongoing NCIC CTG MA.32 trial of adjuvant metformin. The potential significance of these data for metformin in the treatment of breast cancer is discussed here.

Dissecting the Dual Role of AMPK in Cancer: From Experimental to Human Studies

The precise role of 5'AMP-activated kinase (AMPK) in cancer and its potential as a therapeutic target is controversial. Although it is well established that activation of this energy sensor inhibits the main anabolic processes that sustain cancer cell proliferation and growth, AMPK activation can confer on cancer cells the plasticity to survive under metabolic stress such as hypoxia and glucose deprivation, which are commonly observed in fast growing tumors. Thus, AMPK is referred to as both a "conditional" tumor suppressor and "contextual" oncogene. To add a further layer of complexity, AMPK activation in human cancer tissues and its correlation with tumor aggressiveness and progression appears to vary in different contexts. The current review discusses the different faces of this metabolic regulator, the therapeutic implications of its modulation, and provides an overview of the most relevant data available on AMPK activation and AMPK-activating drugs in human studies.