Metformin potentiates the anticancer effects of cisplatin under normoxic conditions in vitro

Anti-Cancer and Radio-Sensitizing Properties of New Bimetallic (N-Heterocyclic Carbene)-Amine-Pt(II) Complexes

Bioactive NHC-transition metal complexes have shown promise as anti-cancer agents, but their potential use as radiosensitizers has been neglected so far. We disclose here a new series of bimetallic platinum(II) complexes displaying NHC-type bridging ligands, (bis-NHC)[trans-Pt(RNH₂)I₂]₂, that have been synthesized via a simple, two-step procedure. They display cytotoxicity in the micromolar range on cancerous cell lines, accumulate in cells, and bind to genomic DNA, by inducing DNA damages. Notably, these bimetallic complexes demonstrate significant radiosensitizing effects on both ovarian cells A2780 and nonsmall lung carcinoma cells H1299. Further investigations revealed that bimetallic species make irradiation-induced DNA damages more persistent by inhibiting repair mechanisms. Indeed, a higher and persistent accumulation of both γ-H2AX and 53BP1 foci post-irradiation was detected, in the presence of the NHC-Pt complexes. Overall, we provide the first in vitro evidence for the radiosensitizing properties of NHC-platinum complexes, which suggests their potential use in combined chemo-radio therapy protocols.

Metformin attenuates the production and proliferative effects of prolactin induced by medroxyprogesterone acetate during fertility-sparing treatment for endometrial cancer

Background

Progestin is used for fertility-sparing treatment in cases of endometrial cancer (EC). Progestin can induce hyperprolactinemia by increasing pituitary secretion and endometrial decidualization. However, progestin induces prolactin (PRL) secretion, which stimulates cell proliferation and deleteriously affects treatment. To date, the detrimental effect of PRL, the secretion of which is induced by medroxyprogesterone acetate (MPA) during fertility-sparing treatment, has not yet been fully elucidated. Therefore, we aimed to assess the effects of PRL on EC cells during combined treatment with progestin and metformin.

Methods

In total, 71 patients with EC/endometrial atypical hyperplasia who underwent fertility-sparing treatment at our institution from 2009–2019 were enrolled. Serum PRL levels were determined using enzyme immunoassays; mRNA levels in endometrial tissues were determined using quantitative reverse-transcription PCR. To evaluate MPA-induced decidualization, cancer-associated stromal cells were enzymatically released from surgically removed specimens of six patients with EC. To examine PRL-induced cell proliferation, the EC cell lines Ishikawa, HEC1B, and HEC265 were used. In vitro cell proliferation was evaluated using the WST assay; protein levels of signaling molecules were determined using western blotting.

Results

MPA administration significantly increased serum PRL levels at 3 and 6 months and upregulated IGFBP-1 and PRL mRNA expression in tissues at 3 months of fertility-sparing treatment. Metformin significantly reduced MPA-induced IGFBP-1 and PRL mRNA expression during fertility-sparing treatment and significantly inhibited the upregulation of IGFBP-1 and PRL mRNA and PRL levels due to decidualization induced by MPA and cAMP treatment in primary cultured EC stromal cells. In vitro, PRL increased cell proliferation and ERK1/2 phosphorylation levels, whereas metformin attenuated these increases.

Conclusions

MPA upregulated PRL levels in serum and endometrial tissues during fertility-sparing treatment. Metformin co-administration reduced PRL production and attenuated PRL-induced cell-proliferation activity. This study may provide valuable insights on the application of metformin to improve the outcomes of fertility-sparing treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09858-w.

Combined regimens of cisplatin and metformin in cancer therapy: A systematic review and meta-analysis

INTRODUCTION

Cancer cell resistance to chemotherapy agents is a challenging issue in treating patients with cancer. Findings suggest that a combination of drugs may have synergistic or additive effects. in the present study, we systematically reviewed the combined regimens of metformin with cisplatin in various treating cancers.

METHODS

A comprehensive systematic search was performed in PubMed, Scopus, Embase, and other relevant databases with the following keyword "metformin", "cisplatin", "combination", "using all their equivalents and similar terms. Pooled odds ratio (OR) and 95% confidence intervals of cell viability and tumor volume as primary outcomes were calculated using Der-Simonian and Laird method while random effects meta-analysis was used, taking into account clinical and statistical heterogeneity.

RESULTS

Overall, 44 studies were retrieved, Findings of the present meta-analysis showed that combined regimens of metformin plus cisplatin was significantly associated with decreased odds of tumor volume and cell viability for all cancers compared with cisplatin alone (pooled OR: 0.40; 95% CI: 0.27, 0.58) and (pooled OR: 0.49; 95% CI: 0.42, 0.58) respectively. The result was same for cell viability in lung cancer (pooled OR: 0.59; 95% CI: 0.49, 0.70). The tumor size reduction and the response rate were evident in the animal xenografts model.

CONCLUSION

Findings indicated that combining metformin with cisplatin is a practical therapeutic approach to increase treatment efficacy in the case of cell viability and tumor volume and minimize side effects. A combination of metformin with cisplatin could enhance treatment efficacy through synergistic inhibitory effects on the growth of cancer cells.

The effect of metformin on viability and mitochondrial status of tumor and non-tumor cell line

Introduction: Metformin is a drug of choice in the therapy of type II Diabetes mellitus. There is a growing evidence of metformin's antitumor activity, but the suggested mechanisms of such activity are still not fully elucidated. Aim: To investigate the effect of therapeutic doses of metformin on viability and mitochondrial status of human non-small cell lung carcinoma (NCI-H460) and human immortalized lung fibroblasts (MRC-5) cell lines. Material and methods: Acid phosphatase and Crystal Violet assays were used for the determination of NCI-H460 and MRC-5 cell viability after the treatment with metformin (10-60 µM) for 1-7 days. Mitochondrial membrane potential, production of reactive oxygen species and superoxide anion, as well as mitochondrial mass were measured using flow cytometry after the treatment of the cells for 3, 24 and 120 h, followed by staining with appropriate fluorochromes: JC-1, DHR, DHE and Mitotracker Red. Results: Metformin did not change the viability of both NCI-H460 and MRC-5 cells in all investigated time-points and all used concentrations. Depolarization of mitochondrial membrane was observed 3 h post-treatment in MRC-5 cells. Prolonged treatment (120 h) increased superoxide anion production and mitochondrial mass in NCI-H460 cells. No significant changes in production of reactive oxygen species were observed in both cells lines after short or extended exposure to metformin. Conclusion: : Therapeutic concentrations of metformin do not influence the viability of NCI-H460 and MRC-5 cells, but induce mitochondrial depolarization after short-term exposure in lung fibroblasts and increase production of superoxide anion and mitochondrial mass in lung carcinoma cells after prolonged treatment.

Perspectives of metformin use in endometrial cancer and other gynaecological malignancies

Insulin resistance and hyperinsulinemia play a key role in type 1 endometrial cancer pathogenesis. Most of these cancers develop on a background of overweight or type 2 diabetes mellitus (T2DM). One of the medications widely used in the treatment of T2DM is biguanide derivative, metformin, which exerts promising anticancer properties principally through activation of adenosine monophosphate kinase (AMPK) and inhibition of mammalian target of rapamycin (mTOR) pathways. Many epidemiological studies on diabetic patients show potential preventative role of metformin in endometrial cancer patients, but data regarding its therapeutic role is still limited. So far, most of attention has been paid to the concept of metformin use in fertility sparing treatment of early-stage cancer. Another investigated alternative is its application in patients with primary advanced or recurrent disease. In this review we present the latest data on clinical use of metformin in endometrial cancer patients and potential underlying mechanisms of its activity. Finally, we present some most important clinical information regarding metformin efficacy in other gynaecological malignancies, mainly breast and ovarian cancer.

Knockdown of LKB1 Sensitizes Endometrial Cancer Cells via AMPK Activation

Metformin is an anti-diabetic drug and has anticancer effects on various cancers. Several studies have suggested that metformin reduces cell proliferation and stimulates cell-cycle arrest and apoptosis. However, the definitive molecular mechanism of metformin in the pathophysiological signaling in endometrial tumorigenesis and metastasis is not clearly understood. In this study, we examined the effects of metformin on the cell viability and apoptosis of human cervical HeLa and endometrial HEC-1-A and KLE cancer cells. Metformin suppressed cell growth in a dose-dependent manner and dramatically evoked apoptosis in HeLa cervical cancer cells, while apoptotic cell death and growth inhibition were not observed in endometrial (HEC-1-A, KLE) cell lines. Accordingly, the p27 and p21 promoter activities were enhanced while Bcl-2 and IL-6 activities were significantly reduced by metformin treatment. Metformin diminished the phosphorylation of mTOR, p70S6K and 4E-BP1 by accelerating adenosine monophosphateactivated kinase (AMPK) in HeLa cancer cells, but it did not affect other cell lines. To determine why the anti-proliferative effects are observed only in HeLa cells, we examined the expression level of liver kinase B1 (LKB1) since metformin and LKB1 share the same signalling system, and we found that the LKB1 gene is not expressed only in HeLa cancer cells. Consistently, the overexpression of LKB1 in HeLa cancer cells prevented metformin-triggered apoptosis while LKB1 knockdown significantly increased apoptosis in HEC-1-A and KLE cancer cells. Taken together, these findings indicate an underlying biological/physiological molecular function specifically for metformin-triggered apoptosis dependent on the presence of the LKB1 gene in tumorigenesis.

Methoxyeugenol regulates the p53/p21 pathway and suppresses human endometrial cancer cell proliferation

ETHNOPHARMACOLOGICAL RELEVANCE

Plant-derived compounds are a reservoir of natural chemicals and can act as drug precursors or prototypes and pharmacological probes. Methoxyeugenol is a natural compound found in plant extracts, such as nutmeg (Myristica fragrans), and it presents anthelmintic, antimicrobial, anti-inflammatory activities. Recently, interest in the anticancer activity of plant extracts is increasing and the therapeutic activity of methoxyeugenol against cancer has not yet been explored.

AIM OF THE STUDY

The present study aimed to evaluate the cancer-suppressive role and the molecular signaling pathways of methoxyeugenol in human endometrial cancer (Ishikawa) cell line.

MATERIALS AND METHODS

Proliferation, viability, and cell toxicity were assessed by direct counting, MTT assay, and LDH enzyme release assay, respectively. Antiproliferative effect were evaluated by nuclear morphological changes along with the cellular mechanisms of apoptosis and senescence by flow cytometry. The underlying molecular and cellular mechanisms were investigated by RT-qPCR, reactive oxygen species (ROS) levels, mitochondrial dysfunction, and proliferative capacity.

RESULTS AND CONCLUSIONS

Methoxyeugenol treatment significantly inhibited the proliferation and viability of Ishikawa cells. Probably triggered by the higher ROS levels and mitochondrial dysfunction, the gene expression of p53 and p21 increased and the gene expression of CDK4/6 decreased in response to the methoxyeugenol treatment. The rise in nuclear size and acidic vesicular organelles corroborate with the initial senescence-inducing signals in Ishikawa cells treated with methoxyeugenol. The antiproliferative effect was not related to cytotoxicity and proved to effectively reduce the proliferative capacity of endometrial cancer cells even after treatment withdrawal. These results demonstrated that methoxyeugenol has a promising anticancer effect against endometrial cancer by rising ROS levels, triggering mitochondrial instability, and modulating cell signaling pathways leading to an inhibition of cell proliferation.

A Cohort Study of Exposure to Antihyperglycemic Therapy and Survival in Patients with Lung Cancer

We evaluated the effect of antihyperglycemic therapy on the survival of patients with lung cancer (LC). The analysis included patients with LC and concomitant type 2 diabetes. 15,929 patients were classified into five groups: metformin users, insulin users, metformin and insulin users, sulphonylurea users and non-diabetic group. A multivariate analysis showed that exposure to either metformin or to insulin was associated with a lower risk of LC-specific mortality, and this approached statistical significance (HR 0.82, 95% CI 0.72–92 for metformin and HR 0.65, 95% CI 0.44–95 for insulin). When deaths from all causes were considered, only metformin exposure was associated with a significantly lower risk of death (HR 0.82, 95% CI 0.73–0.92). Users of sulphonylurea were at a higher risk of LC-specific and overall mortality (HRs 1.19, 95% CI 0.99–1.43 and 1.22, 95% CI 1.03–1.45). Our study shows a positive effect of metformin on the survival of patients with LC. Moreover, our results show that exposure to insulin was associated with a lower risk of LC-specific mortality, but not with deaths from all causes. The study results suggested that users of sulphonylurea may be at a higher risk of LC-specific and overall mortality.

Hypoxia and hyperglycaemia determine why some endometrial tumours fail to respond to metformin

BACKGROUND

High expression of Ki67, a proliferation marker, is associated with reduced endometrial cancer-specific survival. Pre-surgical metformin reduces tumour Ki-67 expression in some women with endometrial cancer. Metformin's anti-cancer activity may relate to effects on cellular energy metabolism. Since tumour hypoxia and glucose availability are major cellular redox determinants, we evaluated their role in endometrial cancer response to metformin.

METHODS

Endometrial cancer biopsies from women treated with pre-surgical metformin were tested for the hypoxia markers, HIF-1α and CA-9. Endometrial cancer cell lines were treated with metformin in variable glucose concentrations in normoxia or hypoxia and cell viability, mitochondrial biogenesis, function and energy metabolism were assessed.

RESULTS

In women treated with metformin (n = 28), Ki-67 response was lower in hypoxic tumours. Metformin showed minimal cytostatic effects towards Ishikawa and HEC1A cells in conventional medium (25 mM glucose). In low glucose (5.5 mM), a dose-dependent cytostatic effect was observed in normoxia but attenuated in hypoxia. Tumours treated with metformin showed increased mitochondrial mass (n = 25), while in cultured cells metformin decreased mitochondrial function. Metformin targets mitochondrial respiration, however, in hypoxic, high glucose conditions, there was a switch to glycolytic metabolism and decreased metformin response.

CONCLUSIONS

Understanding the metabolic adaptations of endometrial tumours may identify patients likely to derive clinical benefit from metformin.

PCK1 negatively regulates cell cycle progression and hepatoma cell proliferation via the AMPK/p27Kip1 axis

Background

Altered glucose metabolism endows tumor cells with metabolic flexibility for biosynthesis requirements. Phosphoenolpyruvate carboxykinase 1 (PCK1), a key enzyme in the gluconeogenesis pathway, is downregulated in hepatocellular carcinoma (HCC) and predicts poor prognosis. Overexpression of PCK1 has been shown to suppress liver tumor growth, but the underlying mechanism remains unclear.

Methods

mRNA and protein expression patterns of PCK1, AMPK, pAMPK, and the CDK/Rb/E2F pathway were determined using qRT-PCR and western blotting. Cell proliferation ability and cell cycle were assessed by MTS assay and flow cytometric analysis. The effect of PCK1 on tumor growth was examined in xenograft implantation models.

Results

Both gain and loss-of-function experiments demonstrated that PCK1 deficiency promotes hepatoma cell proliferation through inactivation of AMPK, suppression of p27^Kip1 expression, and stimulation of the CDK/Rb/E2F pathway, thereby accelerating cell cycle transition from the G1 to S phase under glucose-starved conditions. Overexpression of PCK1 reduced cellular ATP levels and enhanced AMPK phosphorylation and p27^Kip1 expression but decreased Rb phosphorylation, leading to cell cycle arrest at G1. AMPK knockdown significantly reversed G1-phase arrest and growth inhibition of PCK1-expressing SK-Hep1 cells. In addition, the AMPK activator metformin remarkably suppressed the growth of PCK1-knockout PLC/PRF/5 cells and inhibited tumor growth in an orthotropic HCC mouse model.

Conclusion

This study revealed that PCK1 negatively regulates cell cycle progression and hepatoma cell proliferation via the AMPK/p27^Kip1 axis and supports a potential therapeutic and protective effect of metformin on HCC.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1029-y) contains supplementary material, which is available to authorized users.

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.

Linking type 2 diabetes and gynecological cancer: an introductory overview

Type 2 diabetes (T2D) is a chronic disease with a growing prevalence and a leading cause of death in many countries. Several epidemiological studies observed an association between T2D and increased risk of many types of cancer, such as gynecologic neoplasms (endometrial, cervical, ovarian and vulvar cancer). Insulin resistance, chronic inflammation and high free ovarian steroid hormones are considered the possible mechanisms behind this complex relationship. A higher risk of endometrial cancer was observed in T2D, even though this association largely attenuated after adjusting for obesity. A clear relationship between the incidence of cervical cancer (CC) and T2D has still not be determined; however T2D might have an impact on prognosis in patients with CC. To date, studies on the association between T2D and ovarian cancer (OC) are limited. The effect of pre-existing diabetes on cancer-specific mortality has been evaluated in several studies, with less clear results. Other epidemiological and experimental studies focused on the potential role of diabetes medications, mainly metformin, in cancer development in women. The correct understanding of the link between T2D and gynecologic cancer risk and mortality is currently imperative to possibly modify screening and diagnostic-therapeutic protocols in the future.

Metformin Increases E-cadherin in Tumors of Diabetic Patients With Endometrial Cancer and Suppresses Epithelial-Mesenchymal Transition in Endometrial Cancer Cell Lines

PURPOSE

Epithelial-mesenchymal transition (EMT) is a critical process for cancer metastasis and recurrence. Metformin, an effective oral antidiabetic drug, has been associated with decreased cancer risk and mortality. In this pilot study, we started to evaluate the effect of metformin on EMT in vivo and in vitro in endometrial cancer (EC).

METHODS

Endometrial cancer cell lines and freshly isolated EC tumor specimens were used to assess EMT after metformin treatment. Cell lines were subjected to wound healing and AlamarBlue assays to determine cell migration and cell proliferation; messenger RNA levels were measured by real-time reverse transcriptase (RT) quantitative polymerase chain reaction (PCR), and protein levels were measured by Western blots to detect EMT marker expression.

RESULTS

Protein expression and messenger RNA of E-cadherin was found to be increased (P = 0.02 and 0.04, respectively) in 30 EC tumor specimens of diabetic patients treated with metformin compared with 20 EC tumor specimens of diabetic patients treated with other antidiabetic agents. In vitro, metformin reduced cell migration at 5 mM for 48 hours, as determined by the wound healing assay in EC cell lines (Ishikawa, 45% reduction; HEC50, 40% reduction), whereas more than 90% of the cells remained viable on the AlamarBlue assay. Metformin reduced EMT in the cell lines and regulated the expression of the EMT-related epithelial markers, E-cadherin and Pan-keratin; the mesenchymal markers, N-cadherin, fibronectin, and vimentin; and the EMT drivers, Twist-1, snail-1, and ZEB-1.

CONCLUSIONS

Tumors of patients on metformin have increased E-cadherin expression, and metformin decreases EMT in EC cell lines in vitro, suggesting clinical biological relevance of metformin in women with EC.

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.

Redox-dependent modulation of metformin contributes to enhanced sensitivity of esophageal squamous cell carcinoma to cisplatin

Glutathione is the major intracellular anti-oxidant against reactive oxygen species and serves as a detoxification essential. The anti-diabetic drug metformin has been showed to exert anti-tumor activity via modulation of redox homeostasis. In this study, we provided evidence that metformin inhibits proliferation and induces apoptosis of esophageal squamous cancer cells. Importantly, we found that metformin acts as pro-oxidant via depletion of intracellular glutathione. Co-treatment with metformin reversed the elevated intracellular glutathione induced by cisplatin and therefore enhanced the sensitivity to cisplatin in vitro and in vivo. Taken together, our data indicate that combination of metformin with cisplatin may represent a novel therapeutic strategy for esophageal squamous cell carcinoma treatment.

Metformin targets multiple signaling pathways in cancer

Metformin, an inexpensive and well-tolerated oral agent commonly used in the first-line treatment of type 2 diabetes, has become the focus of intense research as a candidate anticancer agent. Here, we discuss the potential of metformin in cancer therapeutics, particularly its functions in multiple signaling pathways, including AMP-activated protein kinase, mammalian target of rapamycin, insulin-like growth factor, c-Jun N-terminal kinase/mitogen-activated protein kinase (p38 MAPK), human epidermal growth factor receptor-2, and nuclear factor kappaB pathways. In addition, cutting-edge targeting of cancer stem cells by metformin is summarized.

Metformin use and its effect on survival in diabetic patients with advanced non-small cell lung cancer

Background

Previous population-based studies have demonstrated an association between metformin use and improved survival among diabetic patients with cancer. We sought to analyze the effects of diabetes and its treatment in terms of the survival of patients with lung cancer.

Methods

Overall, 1106 patients with non-small cell lung cancer (94.3 % with stage IV disease) were included. The outcomes were compared between the patients with (n = 186) and without diabetes (n = 920). The characteristics associated with antidiabetic treatment and proper glycemic control (defined as a mean plasma glucose <130 mg/dL) were examined at diagnosis. The overall survivals (OSs) of the different patient populations were analyzed using Kaplan-Meier curves, and a multivariate Cox proportional hazard model was used to determine the influences of the patient and tumor characteristics on survival.

Results

The OS for the entire population was 18.3 months (95 % CI 16.1-20.4). There was no difference in the OSs of the diabetic and non-diabetic patients (18.5 vs 16.4 months, p = 0.62). The diabetic patients taking metformin exhibited a superior OS than did those on other antidiabetic treatments (25.6 vs 13.2 months, p = 0.017). Those with proper glycemic control had a better OS than did those without proper glycemic control and the non-diabetics (40.5 vs 13.2 and 18.5 months, respectively, p < 0.001). Both the use of metformin (HR 0.53, p < 0.0001 and HR 0.57, p = 0.017, respectively) and proper glycemic control (HR 0.49, p < 0.0001 and HR 0.40, p = 0.002, respectively) were significant protective factors in all and only diabetic patients, respectively.

Conclusions

The diabetic patients with proper glycemic control exhibited a better OS than did those without proper glycemic control and even exhibited a better OS than did the patients without diabetes mellitus. Metformin use was independently associated with a better OS.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2658-6) contains supplementary material, which is available to authorized users.

Finding New Tricks for Old Drugs: Tumoricidal Activity of Non-Traditional Antitumor Drugs

Chemotherapy, a traditional method, plays an important role in tumor therapy. Currently, common clinical antitumor drugs have several defects like poor efficacy, side effects, etc. Furthermore, developing new antitumor drugs takes a long time and requires many resources. Recent studies have found that oldies are newbies for the oncologist, such as flavonoid, metformin, aspirin, etc. These non-traditional antitumor drugs (NTADs) are widely used in management of non-cancer diseases, which gained FDA approval for treatment of patients. Increasingly, studies about antitumor action of NTADs have attracted many researchers' interests. A giant amount of studies showed a decrease in cancer incidence in NTAD-treated patients. Several reports outlined a direct inhibitory effect of NTADs on cancer cell growth and antitumoral actions. This review summarized the research progress on antitumor effects of ten NTADs. Retrospective and meta-analyses of trials also showed that these NTADs had preventive effects against cancer in vitro and in vivo. These drugs represent a promising option for cancer treatment, which have clear benefits including clinical safety, obvious curative effect, and saving medical and health resources. Judged from previous reports, future studies will yield valuable data about the profitable effects of these drugs. With a better understanding of its mechanisms of antitumor activity, NTADs may become available for combination with chemotherapy or targeted therapy in clinic.

Combinational strategies of metformin and chemotherapy in cancers

Chemotherapeutic regimens are the most common treatment to inhibit tumor growth, but there is great variability in clinical responses of cancer patients; cancer cells often develop resistance to chemotherapeutics which results in tumor recurrence and further progression. Metformin, an extensively prescribed and well-tolerated first-line therapeutic drug for type 2 diabetes mellitus, has recently been identified as a potential and attractive anticancer adjuvant drug combined with chemotherapeutic drugs to improve treatment efficacy and lower doses. In this review, we summarized the molecular mechanisms underlying anticancer effects of metformin, which included insulin- and AMPK-dependent effects, selectively targeting cancer stem cells, reversing multidrug resistance, inhibition of the tumor metastasis and described the antineoplastic effects of metformin combined with chemotherapeutic agents in digestive system cancers (colorectal, gastric, hepatic and pancreatic cancer), reproductive system cancers (ovarian and endometrial cancer), prostate cancer, breast cancer, lung cancer, etc. Moreover, the clinical trials regarding metformin in combination of chemotherapeutic drugs were presented and the clinical obstacle or limitation related to the potential role of metformin in cancer treatment was also discussed in this review.

5-fluorouracil resistant colon cancer cells are addicted to OXPHOS to survive and enhance stem-like traits

Despite marked tumor shrinkage after 5-FU treatment, the frequency of colon cancer relapse indicates that a fraction of tumor cells survives treatment causing tumor recurrence. The majority of cancer cells divert metabolites into anabolic pathways through Warburg behavior giving an advantage in terms of tumor growth. Here, we report that treatment of colon cancer cell with 5-FU selects for cells with mesenchymal stem-like properties that undergo a metabolic reprogramming resulting in addiction to OXPHOS to meet energy demands. 5-FU treatment-resistant cells show a de novo expression of pyruvate kinase M1 (PKM1) and repression of PKM2, correlating with repression of the pentose phosphate pathway, decrease in NADPH level and in antioxidant defenses, promoting PKM2 oxidation and acquisition of stem-like phenotype. Response to 5-FU in a xenotransplantation model of human colon cancer confirms activation of mitochondrial function. Combined treatment with 5-FU and a pharmacological inhibitor of OXPHOS abolished the spherogenic potential of colon cancer cells and diminished the expression of stem-like markers. These findings suggest that inhibition of OXPHOS in combination with 5-FU is a rational combination strategy to achieve durable treatment response in colon cancer.

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.