Metformin as an antitumor agent in cancer prevention and treatment

Metformin's anticancer odyssey: Revealing multifaceted mechanisms across diverse neoplastic terrains- a critical review

Metformin, initially prescribed as an oral hypoglycemic medication for type 2 diabetes, has recently gained attention for its potential anticancer effects. Its history dates to 1918, when guanidine, a component of the traditional European herb Galega officinalis, was found to reduce glycemia. This review precisely examines the mechanisms underlying Metformin's anticancer effects across various neoplastic conditions. This investigation explores the complex interactions between metformin and major signaling pathways associated with carcinogenesis, including AMP-activated protein kinase (AMPK), mTOR, and insulin-like growth factor (IGF) pathways. The review emphasizes Metformin's diverse effects on angiogenesis, inflammation, apoptosis, and cellular metabolism in cancer cells. Additionally, new data on metformin's capacity to alter the tumor microenvironment and enhance immune surveillance systems against cancer are examined. The review underscores Metformin's potential for repurposing in oncology, emphasizing its clinical relevance as an adjuvant therapy for various cancers. The review provides insightful information about the complex anticancer mechanisms of metformin by combining data from preclinical and clinical studies. These findings not only broaden our knowledge of the effects of metformin but also open new avenues for oncology research and treatment developments.

Exploring the role and application of mitochondria in radiation therapy

Mitochondria are pivotal in cellular energy metabolism, the oxidative stress response and apoptosis. Recent research has focused on harnessing their functions to enhance the efficacy of radiation therapy (RT). This review focuses on the critical functions and applications of mitochondria in radiation therapy, including the targeting of mitochondrial metabolism and the modulation of mitochondria-mediated cell death and immune responses. While these strategies have demonstrated considerable potential in preclinical studies to improve radiotherapy outcomes, challenges remain, such as optimizing drug delivery systems, ensuring safety and overcoming resistance to therapy.

Metformin: new applications for an old drug

Metformin is a biguanide, evolved as one of the most widely used medicines. The applications of this component include but are not limited to reducing blood glucose, weight loss, and polycystic ovary syndrome. Studies about other probable indications have emerged, indicating that this agent can also be utilized for other purposes. In this review, applications of metformin are noticed based on the current evidence. Metformin commonly is used as an off-label drug in non-alcoholic fatty liver disease (NAFLD), but it worsens inflammation and should not be used for this purpose, according to the latest research. Metformin decreased the risk of death in patients with liver cirrhosis. It is an effective agent in the prevention and improvement of survival in patients suffering hepatocellular carcinoma. There is evidence of the beneficial effects of metformin in colorectal cancer, early-stage prostate cancer, breast cancer, urothelial cancer, blood cancer, melanoma, and bone cancer, suggesting metformin as a potent anti-tumor agent. Metformin shows neuroprotective effects and provides a potential therapeutic benefit for mild cognitive impairment and Alzheimer's disease (AD). It also has been shown to improve mental function and reduce the incidence of dementia. Another condition that metformin has been shown to slow the progression of is Duchenne muscular dystrophy. Regarding infectious diseases, tuberculosis (TB) and coronavirus disease (COVID-19) are among the conditions suggested to be affected by metformin. The beneficial effects of metformin in cardiovascular diseases were also reported in the literature. Concerning renal function, studies showed that daily oral administration of metformin could ameliorate kidney fibrosis and normalize kidney structure and function. This study reviewed the clinical and preclinical evidence about the possible benefits of metformin based on recent studies. Numerous questions like whether these probable indications of metformin can be observed in non-diabetics, need to be described by future basic experiments and clinical studies.

Treat more than heat-New therapeutic implications of Cimicifuga racemosa through AMPK-dependent metabolic effects

BACKGROUND

Cimicifuga racemosa extracts (CRE) have obtained a "well-established use status" in the treatment of postmenopausal (i.e., climacteric) complaints, which predominantly include vasomotor symptoms such as hot flushes and sweating, as well as nervousness, irritability, and metabolic changes. Although characteristic postmenopausal complaints are known for a very long time and the beneficial effects of CRE on climacteric symptoms are well accepted, both the pathophysiology of postmenopausal symptoms and the mechanism of action of CREs are not yet fully understood. In particular, current hypotheses suggest that changes in the α-adrenergic and serotonergic signaling pathways secondary to estrogen depletion are responsible for the development of hot flushes.

PURPOSE

Some of the symptoms associated with menopause cannot be explained by these hypotheses. Therefore, we attempted to extend our classic understanding of menopause by integrating of partly age-related metabolic impairments.

METHODS

A comprehensive literature survey was performed using the PubMed database for articles published through September 2021. The following search terms were used: (cimicifuga OR AMPK) AND (hot flush* OR hot flash* OR menopaus* OR osteoporos* OR cancer OR antioxida* OR cardiovasc*). No limits were set with respect to language, and the references cited in the articles retrieved were used to identify additional publications.

RESULTS

We found that menopause is a manifestation of the general aging process, with specific metabolic changes that aggravate menopausal symptoms, which are accelerated by estrogen depletion and associated neurotransmitter dysregulation. Cimicifuga extracts with their metabolic effects mitigate climacteric symptoms but may also modulate the aging process itself. Central to these effects are effects of CRE on the metabolic key regulator, the AMP-activated protein kinase (AMPK).

CONCLUSIONS

As an extension of this effect dimension, other off-label indications may appear attractive in the sense of repurposing of this herbal treatment.

Beneficial Effects of Metformin on the Central Nervous System, with a Focus on Epilepsy and Lafora Disease

Metformin is a drug in the family of biguanide compounds that is widely used in the treatment of type 2 diabetes (T2D). Interestingly, the therapeutic potential of metformin expands its prescribed use as an anti-diabetic drug. In this sense, it has been described that metformin administration has beneficial effects on different neurological conditions. In this work, we review the beneficial effects of this drug as a neuroprotective agent in different neurological diseases, with a special focus on epileptic disorders and Lafora disease, a particular type of progressive myoclonus epilepsy. In addition, we review the different proposed mechanisms of action of metformin to understand its function at the neurological level.

Glucose and fatty acid metabolism involved in the protective effect of metformin against ulipristal-induced endometrial changes in rats

Ulipristal acetate (UPA) is effective in the treatment of uterine fibroids. However, its clinical use is hampered by the development of pathologic progesterone receptor modulator-associated endometrial changes (PAECs). The current study was designed to test the hypothesis that UPA-induced PAECs are associated with deranged expression of some metabolic genes. In addition, metformin can mitigate UPA-induced PAECs through modulating the expression of these genes. In the present study, twenty-eight female non-pregnant, nulligravid Wistar rats were treated with UPA (0.1 mg/kg/day, intragastric) and/or metformin (50 mg/kg/day, intragastric) for 8 weeks. Our results demonstrated that co-treatment with metformin significantly reduced UPA-induced PAECs. In addition, co-treatment with metformin and UPA was associated with significant increase in the Bax and significant reduction in Bcl-2, PCNA, Cyclin-D1and ER-α as compared to treatment with UPA alone. Furthermore, treatment with UPA alone was associated with deranged expression of 3-phosphoglycerate dehydrogenase (3-PHGDH), glucose-6-phosphate dehydrogenase (G6PD), transketolase (TKT), fatty acid synthase (FAS) and CD36. Most importantly, co-treatment with metformin markedly reduced UPA-induced altered expression of these metabolic genes in endometrial tissues. In conclusion, UPA-induced PAECs are associated with altered expression of genes involved in cell proliferation, apoptosis, estrogen receptor, glucose metabolism and lipid metabolism. Co-treatment with metformin abrogated UPA-induced PAECs most likely through the modulation of the expression of these genes.

Melatonin and Metformin Failed to Modify the Effect of Dacarbazine in Melanoma

LESSONS LEARNED

Melatonin did not increase the efficacy of systemic chemotherapy in melanoma. Metformin did not increase the efficacy of systemic chemotherapy in melanoma.

BACKGROUND

Current data support the possibility of antitumor activity of melatonin and metformin.

METHODS

From March 2014 to December 2016, 57 patients with disseminated melanoma received dacarbazine (DTIC) 1,000 mg/m² on day 1 of a 28-day cycle, either as monotherapy (first group) or in combination with melatonin 3 mg p.o. daily (second group) or metformin 850 mg two times a day p.o. daily (third group) as the first-line of chemotherapy. The primary endpoint was objective response rate (ORR). Secondary endpoints were time to progression (TTP), overall survival (OS), immunologic biomarkers, and quality of life.

RESULTS

ORR was 7% and did not differ among the treatment groups. Median TTP was 57, 57, and 47 days, respectively, in the first, second, and third groups (р = .362). Median OS was 236, 422, and 419 days, respectively (p = .712). Two patients from the combinations groups showed delayed response to therapy. The increase of CD3⁺ CD4⁺ HLA-DR⁺ lymphocytes (p = .003), CD3⁺ CD8⁺ HLA-DR⁺ (p = .045), CD3⁺ CD8⁺ lymphocytes (p = .012), CD4⁺ CD25^high CD127^low lymphocytes (p = .029), and overall quantity of lymphocytes (p = .021) was observed in patients with clinical benefit.

CONCLUSION

No benefit was found in either combination over DTIC monotherapy. Delayed responses in melatonin and metformin combination groups were registered. The increase of lymphocyte subpopulations responsible for antitumor immune response demonstrates the immune system's potential involvement in clinical activity.

A review on the cardioprotective mechanisms of metformin against doxorubicin

Doxorubicin (DOX) is an antineoplastic agent obtained from Streptomyces peucetius. It is utilized in treating different kinds of cancers, such as leukemia, lymphoma, and lung, and breast cancers. The main side effect of DOX is cardiotoxicity. Metformin (MET) is an antihyperglycemic drug used for type 2 diabetes treatment. It is proposed that MET has a protective effect against DOX cardiotoxicity. Our review demonstrated that MET has several possible mechanisms of action, which can prevent or at least reduce DOX cardiotoxicity including a decrease of free radical generation and oxidative stress, 5' adenosine monophosphate-activated protein kinase activation, and ferritin heavy chain expression in cardiomyocytes cells. The combination of MET and DOX has been shown to enhance the anticancer activity of DOX by a number of authors. The literature reviewed in the present report supports the hypothesis that MET can reduce the cardiotoxicity that often occurs with DOX treatment.

Intersections and Clinical Translations of Diabetes Mellitus with Cancer Promotion, Progression and Prognosis

The association between cancer and dysglycemia has been well documented. It is underappreciated, however, that sustained dysglycemia could potentially be a catalyst toward a pro-cancer physiologic milieu and/or increase the burden of cancer. Hyperglycemia, hyperinsulinemia and energy metabolism at large impact a cascade of growth pathways, epi/genetic modifications, and mitochondrial changes that could feasibly link to tumor processes. Oxidative stress is a recurring motif in cell dysfunction: in diabetes, oxidative stress and reactive oxygen species (ROS) feature prominently in the damage and demise of pancreatic beta cells, as well as cell damage contributing to diabetes-related complications. Oxidative stress may be one intersection at which metabolic and oncogenic processes cross paths with deleterious results in the development of precancer, cancer, and cancer progression. This would augur for tight glucose control. Regrettably, some medical societies have recently relaxed hemoglobin A1c targets. A framework for the hyperglycemic state is presented that helps account and translate the full scope of effects of dysglycemia to ultimately improve clinical best practices.

Metformin Induces Apoptosis and Inhibits Proliferation through the AMP-Activated Protein Kinase and Insulin-like Growth Factor 1 Receptor Pathways in the Bile Duct Cancer Cells

Background/Aims: Metformin has been found to have antineoplastic activity in some cancer cells. This study was performed to determine whether metformin inhibits the proliferation of bile duct cancer cells by inducing apoptosis and its effects on the expression of gene-related proteins involved in cancer growth.

Methods: Human extrahepatic bile duct cancer cells (SNU-245 and SNU-1196) were cultured. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays were performed to determine the effect of metformin on the cell proliferation. Apoptosis was measured by a cell death detection enzyme-linked immunosorbent assay and a caspase-3 activity assay. Expression levels of various proteins, with or without specific small interfering ribonucleic acid-induced gene disruption, were measured by Western blot analysis. The migratory activity of the cancer cells was evaluated by wound healing assay.

Results: Metformin suppressed cell proliferation in bile duct cancer cells by inducing apoptosis. Metformin inhibited mammalian target of rapamycin (mTOR) by activation of tuberous sclerosis complex 2 (TSC-2) through phosphorylation of adenosine monophosphate-activated protein kinase at threonine-172 (AMPK^Thr172). Hyperglycemia impaired metformin-induced AMPK^Thr172 activation and enhanced phosphorylation of AMPK at serine-485 (AMPK^Ser485). Metformin blocked the inhibitory effect of insulin-like growth factor 1 receptor (IGF-1R)/insulin receptor substrate 1 (IRS-1) pathway on TSC-2, and hyperglycemia impaired metformin-induced inhibition of IGF-1R/IRS-1 pathway and modulated the invasiveness of bile duct cancer cells; however, this effect was impaired by hyperglycemia.

Conclusions: Metformin has antineoplastic effects in bile duct cancer, and hyperglycemic environment interrupts the effect of metformin. In addition, AMPK and IGF-1R play a key role in the proliferation of bile duct cancer cells.

Repurposed Biguanide Drugs in Glioblastoma Exert Antiproliferative Effects via the Inhibition of Intracellular Chloride Channel 1 Activity

The lack of in-depth knowledge about the molecular determinants of glioblastoma (GBM) occurrence and progression, combined with few effective and BBB crossing-targeted compounds represents a major challenge for the discovery of novel and efficacious drugs for GBM. Among relevant molecular factors controlling the aggressive behavior of GBM, chloride intracellular channel 1 (CLIC1) represents an emerging prognostic and predictive biomarker, as well as a promising therapeutic target. CLIC1 is a metamorphic protein, co-existing as both soluble cytoplasmic and membrane-associated conformers, with the latter acting as chloride selective ion channel. CLIC1 is involved in several physiological cell functions and its abnormal expression triggers tumor development, favoring tumor cell proliferation, invasion, and metastasis. CLIC1 overexpression is associated with aggressive features of various human solid tumors, including GBM, in which its expression level is correlated with poor prognosis. Moreover, increasing evidence shows that modification of microglia ion channel activity, and CLIC1 in particular, contributes to the development of different neuropathological states and brain tumors. Intriguingly, CLIC1 is constitutively active within cancer stem cells (CSCs), while it seems less relevant for the survival of non-CSC GBM subpopulations and for normal cells. CSCs represent GBM development and progression driving force, being endowed with stem cell-like properties (self-renewal and differentiation), ability to survive therapies, to expand and differentiate, causing tumor recurrence. Downregulation of CLIC1 results in drastic inhibition of GBM CSC proliferation in vitro and in vivo, making the control of the activity this of channel a possible innovative pharmacological target. Recently, drugs belonging to the biguanide class (including metformin) were reported to selectively inhibit CLIC1 activity in CSCs, impairing their viability and invasiveness, but sparing normal stem cells, thus representing potential novel antitumor drugs with a safe toxicological profile. On these premises, we review the most recent insights into the biological role of CLIC1 as a potential selective pharmacological target in GBM. Moreover, we examine old and new drugs able to functionally target CLIC1 activity, discussing the challenges and potential development of CLIC1-targeted therapies.

Model-based in silico analysis of the PI3K/Akt pathway: the elucidation of cross-talk between diabetes and breast cancer

BACKGROUND

A positive association between diabetes and breast cancer has been identified by various epidemiological and clinical studies. However, the possible molecular interactions between the two heterogeneous diseases have not been fully determined yet. There are several underlying mechanisms which may increase the risk of breast cancer in diabetic patients.

INTRODUCTION

In this study, we focused on the role of O-GlcNAc transferase (OGT) enzyme in the regulation of phosphatidylinositol-3 kinase (PI3K) pathway through activation/deactivation of Akt protein. The efficiency of insulin signaling in adipocytes is reduced as a result of OGT overexpression which further attenuates Akt signaling; as a result, the efficiency of insulin signaling is reduced by downregulation of insulin-responsive genes. On the other hand, increased expression of OGT results in Akt activation in breast cancer cells, leading to enhanced cell proliferation and inhibition of the apoptosis. However, the interplay amongst these signaling pathways is still under investigation.

METHODS

In this study, we used Petri nets (PNs) to model and investigate the role of PI3K and OGT pathways, acting as key players in crosstalk between diabetes and breast cancer, resulting in progression of these chronic diseases. Moreover, in silico perturbation experiments were applied on the model to analyze the effects of anti-cancer agents (shRNA and BZX) and anti-diabetic drug (Metformin) on the system.

RESULTS

Our PN model reflects the alterations in protein expression and behavior and the correlation between breast cancer and diabetes. The analysis proposed two combination therapies to combat breast cancer progression in diabetic patients including combination of OGTmRNA silencing and OGT inhibitor (BZX) as first combination and BZX and Metformin as the second.

CONCLUSION

The PN model verified that alterations in O-GlcNAc signaling affect both insulin resistance and breast cancer. Moreover, the combination therapy for breast cancer patients consisting of anti-diabetic drugs such as Metformin along with OGT inhibitors, for example BZX, can produce better treatment regimens.

Metformin, a first-line drug for type 2 diabetes mellitus, disrupts the MALAT1/miR-142-3p sponge to decrease invasion and migration in cervical cancer cells

The molecular mechanisms underlying the anti-neoplastic properties of metformin, a first-line drug for type 2 diabetes, remain elusive. To explore the novel anti-neoplastic mechanisms of metformin, the transwell chamber and wound-healing assays were used to evaluate its effects on the migration and invasion of human cervical cancer cells. Real-time PCR and Western blotting were used to measure the gene and protein expression, respectively, of microRNA (miRNA) miR-142-3p, long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript-1 (MALAT1), and high-mobility group AT-hook 2 (HMGA2). The dual-luciferase reporter assay system was used to examine the direct interaction between miR-142-3p and lncRNA MALAT1 and HMGA2. Immunofluorescence was used to detect the protein expression of HMGA2. In addition, tumor xenografts in a nude mouse model were developed to evaluate the anti-tumor efficacy of metformin. We found that metformin could suppress cervical cancer migration and invasion. During the process of tumor metastasis, miR-142-3p was significantly upregulated, whereas lncRNA MATAL1 and HMGA2 were suppressed by metformin. The binding site that allow the direct interaction between miR-142-3p and MALAT1 were located in the 3' untranslated region (3' UTR) of lncRNA MATAL1 and HMGA2 at base pairs (bp) 4452-5255, while that between miR-142-3p and HMGA2 was located at bp 1562-2521 of HMGA2. Metformin markedly inhibited the growth and angiogenesis of SiHa xenografts in nude mice. In conclusion, this study provides evidence that metformin can prevent the MALAT1/miR-142-3p sponge from developing anti-neoplastic properties in human cervical cancer cells and cervical cancer cell xenografts in nude mice. Thus, our findings demonstrate the novel anti-tumor effects of metformin in cervical cancer.

Inhibition of the IGF signaling pathway reverses cisplatin resistance in ovarian cancer cells

Background

This study was aimed at investigating whether metformin can reverse the resistance of ovarian cancer cells to cisplatin and exploring the underlying mechanism.

Methods

Ovarian cancer cell proliferation in vitro was evaluated using a CCK-8 assay. The resistance index of platinum-resistant ovarian cancer cells was determined and cell cycle and apoptosis rate determined by annexin V/propidium iodide double-staining in CP70 cells. Western blotting was used to determine IGF1, IGF1R, AKT, p-IGF1, p-IGF1R, p-AKT, and MRP2 levels in cells treated with different concentrations of metformin and LY29400, an inhibitor of the insulin-like growth factor pathway. Changes in gene expression levels of MRP2, IGF1, IGF1R, and AKT were determined by fluorescence real-time quantitative PCR assay of CP70 cells treated with metformin. Tumors of human ovarian cancer cell lines CP70 and A2780 were established by subcutaneous transplantation of cells in nude mice and the effect of metformin on MRP2 expression and tumor inhibition assessed.

Results

The IC₅₀ value of cisplatin in CP70 cells decreased significantly as metformin concentration increased (P < 0.05). The cell cycle distribution in CP70 cells changed with metformin treatment; the percentage of cells in the G0/G1 phase, as well as the natural apoptosis rate was significantly increased with metformin treatment (P < 0.05). IGF1, IGF1R, AKT p-IGF1, p-IGF1R, and p-Akt protein expression was enhanced dose-dependently with metformin, and was also significantly changed by treatment of CP70 cells with 0 mM metformin +10 mM LY294002. Moreover, changes in the expression of MRP2, IGF1, IGF1R, and AKT was metformin-concentration dependent, and was significantly different from that in the untreated control group (P < 0.05). In nude mice, the tumor volumes of the cisplatin-treated groups were significantly less than in the control group, and was further suppressed by co-treatment with cisplatin and metformin (P < 0.05), indicating that these 2 drugs had a synergistic effect on tumor inhibition.

Conclusion

Metformin can improve the sensitivity of ovarian cancer CP70 cells to cisplatin in a concentration-dependent manner by activating the AKT signaling pathway, inhibiting the IGF1R signaling pathway, and reducing MRP2 expression.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3840-1) contains supplementary material, which is available to authorized users.

Impact of Diabetes on Outcomes of Sorafenib Therapy for Hepatocellular Carcinoma

BACKGROUND

Patients with diabetes are at increased risk of developing hepatocellular carcinoma (HCC) and have a poorer prognosis as compared to non-diabetics when HCC occurs. Diabetics with non-HCC cancers are at higher risk of toxicity related to systemic therapy, but data on HCC are lacking.

OBJECTIVE

The aim of this study was to evaluate safety and effectiveness of sorafenib in HCC patients according to the presence/absence of diabetes.

PATIENTS AND METHODS

From October 2008 to June 2014, 313 patients with HCC treated with sorafenib were enrolled. The patients were staged according to the BCLC system. Treatment response was evaluated according to the mRECIST criteria. The main evaluated outcomes were the overall survival and the safety in the two groups.

RESULTS

Patients were divided in two groups: 80 diabetics (DIAB) and 233 nondiabetics (nDIAB). The median treatment duration was 4 months in DIAB and 3 months in nDIAB. Main adverse events occurred with comparable frequency in both groups, with the exception of rash, that was more frequent among DIAB than in nDIAB: 27.5 % vs 17.6 % (P = .047). The median overall survival was 9 months in nDIAB and 10 months in DIAB group (P = .535). Median time-to-progression (TTP) was longer the in DIAB than the nDIAB group (P = .038).

CONCLUSIONS

Sorafenib was as safe as effective in DIAB and in nDIAB patients. The longer TTP observed among DIAB than in nDIAB patients might suggest a better anticancer effect of sorafenib in patients with diabetes.

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.

Metformin intake associates with better cognitive function in patients with Huntington's disease

Huntington's disease (HD) is an inherited, dominant neurodegenerative disorder caused by an abnormal expansion of CAG triplets in the huntingtin gene (htt). Despite extensive efforts to modify the progression of HD thus far only symptomatic treatment is available. Recent work suggests that treating invertebrate and mice HD models with metformin, a well-known AMPK activator which is used worldwide to treat type 2-diabetes, reduces mutant huntingtin from cells and alleviates many of the phenotypes associated to HD. Herein we report statistical analyses of a sample population of participants in the Enroll-HD database, a world-wide observational study on HD, to assess the effect of metformin intake in HD patients respect to cognitive status using linear models. This cross-sectional study shows for the first time that the use of metformin associates with better cognitive function in HD patients.

Epidemiology of ovarian cancer: a review

Ovarian cancer (OC) is the seventh most commonly diagnosed cancer among women in the world and the tenth most common in China. Epithelial OC is the most predominant pathologic subtype, with five major histotypes that differ in origination, pathogenesis, molecular alterations, risk factors, and prognosis. Genetic susceptibility is manifested by rare inherited mutations with high to moderate penetrance. Genome-wide association studies have additionally identified 29 common susceptibility alleles for OC, including 14 subtype-specific alleles. Several reproductive and hormonal factors may lower risk, including parity, oral contraceptive use, and lactation, while others such as older age at menopause and hormone replacement therapy confer increased risks. These associations differ by histotype, especially for mucinous OC, likely reflecting differences in etiology. Endometrioid and clear cell OC share a similar, unique pattern of associations with increased risks among women with endometriosis and decreased risks associated with tubal ligation. OC risks associated with other gynecological conditions and procedures, such as hysterectomy, pelvic inflammatory disease, and polycystic ovarian syndrome, are less clear. Other possible risk factors include environmental and lifestyle factors such as asbestos and talc powder exposures, and cigarette smoking. The epidemiology provides clues on etiology, primary prevention, early detection, and possibly even therapeutic strategies.

Epidemiology of ovarian cancer: a review

Ovarian cancer (OC) is the seventh most commonly diagnosed cancer among women in the world and the tenth most common in China. Epithelial OC is the most predominant pathologic subtype, with five major histotypes that differ in origination, pathogenesis, molecular alterations, risk factors, and prognosis. Genetic susceptibility is manifested by rare inherited mutations with high to moderate penetrance. Genome-wide association studies have additionally identified 29 common susceptibility alleles for OC, including 14 subtype-specific alleles. Several reproductive and hormonal factors may lower risk, including parity, oral contraceptive use, and lactation, while others such as older age at menopause and hormone replacement therapy confer increased risks. These associations differ by histotype, especially for mucinous OC, likely reflecting differences in etiology. Endometrioid and clear cell OC share a similar, unique pattern of associations with increased risks among women with endometriosis and decreased risks associated with tubal ligation. OC risks associated with other gynecological conditions and procedures, such as hysterectomy, pelvic inflammatory disease, and polycystic ovarian syndrome, are less clear. Other possible risk factors include environmental and lifestyle factors such as asbestos and talc powder exposures, and cigarette smoking. The epidemiology provides clues on etiology, primary prevention, early detection, and possibly even therapeutic strategies.

Review of antidiabetic fruits, vegetables, beverages, oils and spices commonly consumed in the diet

ETHNOPHARMACOLOGICAL RELEVANCE

Type 2 diabetes is the most common type of diabetes and its prevalence is rapidly increasing throughout the world. Modifications of lifestyle such as suitable diet and exercise programs along with pharmacotherapy and education of patients are beneficial therapies for patients with type 2 diabetes. The ethnopharmacological use of herbal medicines, many of them part of our diet as spices, vegetables and fruits, has been developed for the treatment of diabetes due to inexpensiveness, easy availability and few side effects.

AIM OF THE STUDY

Our aim is to present a review for researchers who are interested in the biologically active dietary plants traditionally utilized in the treatment of diabetes.

MATERIALS AND METHODS

Information was obtained from a literature search of electronic databases such as Google Scholar, Pubmed, Sci Finder and Cochrane. Common and scientific name of the fruits, vegetables, beverages, oils and spices and the words 'antidiabetic', 'hypoglycemic', 'anti-hyperglycemic', 'type 2 diabetes' were used as keywords for search.

RESULTS

Certain fruits and vegetables are functional foods and their consumption reduces the incidence of type 2 diabetes. Hypoglycemic effects of fruits and vegetables may be due to their inducing nature on pancreatic β-cells for insulin secretion, or bioactive compounds such as flavonoids, alkaloids and anthocyanins, which act as insulin-like molecules or insulin secretagogues.

CONCLUSION

This write-up covers hypoglycemic, anti-hyperglycemic and anti-diabetic activities of some dietary fruits, vegetables, beverages, oils and spices and their active hypoglycemic constituents. Including such plant species in the diet might improve management of type 2 diabetes.

Metformin and improved treatment outcomes in radiation therapy - A review

BACKGROUND

Metformin, a primary treatment for diabetes mellitus (DM) patients, is associated with improved outcomes for diabetic cancer patients fuelling further investigation on its mechanisms of action. The radiosensitising properties of metformin are increasingly reported in pre-clinical studies. This review discusses whether metformin should be offered to radiotherapy (RT) cancer patients as a means to improve their treatment outcomes.

MATERIALS AND METHODS

A database search was conducted for articles published with metformin as the main intervention between 2010 and 2016. Three groups of RT cancer patients were analysed: diabetic patients using metformin, diabetic patients not using metformin and non-diabetic patients not using metformin. Data on survival and recurrence metrics were extracted.

RESULTS

Thirteen studies were included. Conflicting evidence exists with regards to the impact of metformin administration on recurrence and survival outcomes following radiotherapy. Three studies reported improved tumour response determined by recurrence rates while five studies did not observe differences or metformin use was not the associated reason. One study revealed inconsistent tumour response results. Metformin was reported as improving survival outcomes in 2 studies and not improving outcomes in 5 studies. 4 studies showed indefinite results.

CONCLUSION

Although metformin may improve tumour response in the non-randomized, retrospective studies analysed, it may not necessarily confer survival benefits. Future prospective and randomised trials are required to translate the positive impact of metformin documented in pre-clinical and retrospective studies into improve management of RT cancer patients.

Epidemiology of ovarian cancer: a review

Ovarian cancer (OC) is the seventh most commonly diagnosed cancer among women in the world and the tenth most common in China. Epithelial OC is the most predominant pathologic subtype, with five major histotypes that differ in origination, pathogenesis, molecular alterations, risk factors, and prognosis. Genetic susceptibility is manifested by rare inherited mutations with high to moderate penetrance. Genome-wide association studies have additionally identified 29 common susceptibility alleles for OC, including 14 subtype-specific alleles. Several reproductive and hormonal factors may lower risk, including parity, oral contraceptive use, and lactation, while others such as older age at menopause and hormone replacement therapy confer increased risks. These associations differ by histotype, especially for mucinous OC, likely reflecting differences in etiology. Endometrioid and clear cell OC share a similar, unique pattern of associations with increased risks among women with endometriosis and decreased risks associated with tubal ligation. OC risks associated with other gynecological conditions and procedures, such as hysterectomy, pelvic inflammatory disease, and polycystic ovarian syndrome, are less clear. Other possible risk factors include environmental and lifestyle factors such as asbestos and talc powder exposures, and cigarette smoking. The epidemiology provides clues on etiology, primary prevention, early detection, and possibly even therapeutic strategies.

Diabetes Mellitus and Risk of Colorectal Cancer Mortality in Japan: the Japan Collaborative Cohort Study

Objective:

Our aim was to estimate whether diabetes mellitus (DM) may be associated with an increased risk of colorectal cancer (CRC) mortality in Japan.

Methods:

The Japan Collaborative Cohort (JACC) Study is a nationwide prospective study, initiated in 1988, which involves 110,585 subjects (age range: from 40 to 79 years; 46,395 males and 64,190 females). Our present analysis population comprised 96,081 (40,510 men and 55,571 women) who provided details on DM history. The questionnaire also included age, sex, weight, height, family history of CRC, smoking, drinking and exercise habits, and education. Cox proportional-hazard regression was used to estimate the hazard ratio (HR). We used SPSS 21 software to analyze all data.

Results:

Among the participants with DM, we followed up for 71,174 person-years and 640. deaths from CRC were confirmed; and, among the non-diabetic participants, 785 CRC deaths were identified during 1,499,324 person-years. After adjusting for multivariate confounding factors, such as age, sex, body mass index (BMI), family history of colorectal cancer, smoking habit, drinking habit, physical activity (sports and walking) and education, DM was associated with an increased risk of CRC death (HR 1.4, 95% confidence interval [CI] 1.0-2.0). Diabetic women, but not diabetic men, experienced increased mortality from CRC (HR 1.7, 95% CI 1.0-3.0).

Conclusion:

The risk of CRC mortality is significantly increased in both sexes and women with diabetes, but no significant increase was seen for diabetic men among Japanese.

Metformin Is Associated With Slightly Reduced Risk of Colorectal Cancer and Moderate Survival Benefits in Diabetes Mellitus: A Meta-Analysis

To systematically assess the effect of metformin on colorectal cancer (CRC) risk and mortality in type 2 diabetes mellitus (T2DM) patients. We conducted a systematic search of PubMed, Web of Science, and the Cochrane Library databases for relevant articles before August 2015. Two investigators identified and extracted data independently. We adopted adjusted estimates to calculate summary estimates with 95% confidence interval (CI) using either a fixed-effects or a random-effects model. Subgroup and sensitivity analyses were conducted to evaluate the robustness of the pooled results. The risk of publication bias was assessed by examining funnel plot asymmetry as well as Begg test and Egger test. Fifteen studies on CRC incidence and 6 studies on CRC survival were finally included in our meta-analysis. The pooled odds ratio (OR) of observational studies illustrated that a slight 10% reduction of CRC incidence was associated with metformin use (OR = 0.90, 95% CI: 0.85-0.96). Furthermore, the pooled hazard ratio (HR) revealed an improved survival outcome for metformin users in CRC patients compared to nonusers (HR = 0.68, 95% CI: 0.58-081). There was no publication bias across studies. Our meta-analysis demonstrated that metformin therapy could slightly reduce CRC incidence and moderately improve the survival outcomes in patients with T2DM. More prospective studies are warranted to certify this protective association.

Effect of metformin and adriamycin on transplantable tumor model

Adriamycin is a cytotoxic anthracycline antibiotic used in treatment of many types of cancer. Metformin is antidiabetic drug and is under investigation for treatment of cancer. The aim of this work was to study the effect of each of adriamycin and metformin alone and in combination on solid Ehrlich carcinoma (SEC) in mice. Eighty BALB/C mice were divided into four equal groups: SEC group, SEC+adriamycin, SEC+metformin, SEC+adriamycin+metformin. Tumor volume, survival rate, tissue catalase, tissue reduced glutathione, tissue malondialdehyde, tissue sphingosine kinase 1 activity, tissue caspase 3 activity and tissue tumor necrosis factor alpha were determined. A part of the tumor was examined for histopathological and immunohistochemical study. Adriamycin or metformin alone or in combination induced significant increase in the survival rate, tissue catalase, reduced glutathione and tissue caspase 3 activity with significant decrease in tumor volume, tissue malondialdehyde, tissue sphingosine kinase 1 activity and tumor necrosis factor alpha and alleviated the histopathological changes with significant increase in Trp53 expression and apoptotic index compared to SEC group. In conclusion, the combination of adriamycin and metformin had a better effect than each of these drugs alone against transplantable tumor model in mice.

Systematic review: Preventive and therapeutic applications of metformin in liver disease

Metformin, a biguanide derivative, is the most commonly prescribed medication in the treatment of type 2 diabetes mellitus. More recently, the use of metformin has shown potential as a preventive and therapeutic agent for a broad spectrum of conditions, including liver disease and hepatic malignancies. In this systematic review, we critically analyze the literature behind the potential use of metformin across the spectrum of liver disease and malignancies. The PubMed and Ovid MEDLINE databases were searched from 2000 to March 2015, using a combination of relevant text words and MeSH terms: metformin and mammalian target of rapamycin, hepatitis B virus (HBV), hepatitis B virus (HCV), non-alcoholic fatty liver disease (NAFLD), hepatocellular carcinoma (HCC) or cholangiocarcinoma. The search results were evaluated for pertinence to the issue of metformin in liver disease as well as for quality of study design. Metformin has a number of biochemical effects that would suggest a benefit in treating chronic liver diseases, particularly in the context of insulin resistance and inflammation. However, the literature thus far does not support any independent therapeutic role in NAFLD or HCV. Nonetheless, there is Level III evidence for a chemopreventive role in patients with diabetes and chronic liver disease, with decreased incidence of HCC and cholangiocarcinoma. The use of metformin seems to be safe in patients with cirrhosis, and provides a survival benefit. Once hepatic malignancies are already established, metformin does not offer any therapeutic potential. In conclusion, there is insufficient evidence to recommend use of metformin in the adjunctive treatment of chronic liver diseases, including NAFLD and HCV. However, there is good evidence for a chemopreventive role against HCC among patients with diabetes and chronic liver disease, and metformin should be continued in patients even with cirrhosis to provide this benefit.

Prevention of hepatocellular carcinoma by correction of metabolic abnormalities: Role of statins and metformin

Hepatocellular carcinoma is the third leading cause of cancer-related deaths in the world. It is associated with an important mortality rate and the incidence is increasing. Patients showing metabolic syndrome seem to have higher incidence and mortality rates from hepatocellular carcinoma than healthy subjects, especially those with type 2 diabetes mellitus and obesity. Thus, metformin and statins, both to treat features of metabolic syndrome, have been proposed to decrease the risk of hepatocellular carcinoma. Otherwise, liver cancer is the result of a complex process which impairs several signaling cascades, such as RAS/RAF/mitogen-activated protein kinase kinase (MEK)/extracellular-signal-regulated kinase (ERK), phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) and Wnt/β-catenin signaling. Metformin (through 5′-adenosine monophosphate-activated protein kinase pathway activation) and statins (through 3-hydroxy-3-methylglutaryl coenzyme A inhibition) show anti-tumoral properties modifying several steps of RAS/RAF/MEK/ERK, PI3K/AKT/mTOR and Wnt/β-catenin signaling cascades. On the other hand, metformin and statins have been found to reduce the risk of hepatocellular carcinoma up to 50% and 60%, respectively. Furthermore, both drugs have shown a dose-dependent protective effect. However, information about chemopreventive role of metformin and statins is mainly obtained of observational studies, which could not take into account some bias. In conclusion, given the rising of incidence of hepatocellular carcinoma and the important morbidity and mortality rates associated with this cancer, looking for chemopreventive strategies is an essential task. Randomized controlled trials are needed to determine the definite role of metformin and statins on the prevention of hepatocellular carcinoma.

Inhibition of phosphatidylinositol-3,4,5-trisphosphate binding to the AKT pleckstrin homology domain by 4-amino-1,2,5-oxadiazole derivatives

4-Amino-1,2,5-oxadiazole derivatives has been developed as an inhibitor of AKT pleckstrin homology domain.

Metformin displays anti-myeloma activity and synergistic effect with dexamethasone in in vitro and in vivo xenograft models

Epidemiologic studies and meta-analyses have suggested that patients with type 2 diabetes mellitus (T2DM) have a higher incidence of malignancies, including myeloma. Metformin is a widely prescribed antidiabetic drug. Recently, researchers have shown that metformin has direct anticancer activity against many tumor cell lines, mainly through activating AMP-activated protein kinase (AMPK) or reducing the blood insulin level. In the present study, we investigated whether metformin exerts an anti-myeloma effect in in vitro and in vivo xenograft models and explored the underlying mechanism. We found that metformin can inhibit proliferation of MM cells by inducing apoptosis and cell cycle arrest in the G0/G1 phase. Western blot showed that metformin activated caspase 3, caspase 9, PARP-1, Bak, and p21 and inactivated Mcl-1, HIAP-1, cyclin D1, CDK4, and CDK6. Metformin inhibited the expression of insulin growth factor-I receptor (IGF-IR), and phosphatidyl inositol 3-kinase (PI3K), protein kinase B (PKB/AKT) and the downstream mammalian target of rapamycin (mTOR). IGF-I blocked metformin-induced MM cell apoptosis and reactivation of the PI3K/AKT/mTOR signaling pathway. Metformin also demonstrated synergistic activity with dexamethasone but not bortezomib to eradicate MM cells in vitro and in vivo, especially in MM.1S cells. We conclude that metformin inhibits MM cell proliferation through the IGF-1R/PI3K/AKT/mTOR signaling pathway. Metformin and dexamethasone combination therapy may be an option for MM treatment.

Hyperglycemia as a risk factor for cancer progression

As the prevalence of diabetes mellitus is substantially increasing worldwide, associated diseases such as renal failure, cardiovascular diseases, fatty liver, and cancers have also increased. A number of cancers such as pancreatic, liver, breast, and female reproductive cancers have shown an increased prevalence and a higher mortality rate in diabetic patients compared to healthy subjects. Thus, this suggests an association between diabetes, especially type 2 diabetes and cancer incidence and progression. Recent studies have suggested that hyperinsulinemia, chronic inflammation and hyperglycemia, all frequently seen in diabetics, may lead to increased tumor growth; the underlying molecular mechanisms of this association are not fully understood. In particular, chronic hyperglycemic episodes could serve as a direct or indirect mediator of the increase in tumor cell growth. Here, we will discuss our current understanding how hyperglycemia and cancer risk may be linked, and what the implications are for the treatment of diabetic cancer patients.

In search of antiaging modalities: evaluation of mTOR- and ROS/DNA damage-signaling by cytometry

This review presents the evidence in support of the IGF-1/mTOR/S6K1 signaling as the primary factor contributing to aging and cellular senescence. Reviewed are also specific interactions between mTOR/S6K1 and ROS-DNA damage signaling pathways. Outlined are critical sites along these pathways, including autophagy, as targets for potential antiaging (gero-suppressive) and/or chemopreventive agents. Presented are applications of flow- and laser scanning- cytometry utilizing phospho-specific Abs, to monitor activation along these pathways in response to the reported antiaging drugs rapamycin, metformin, berberine, resveratrol, vitamin D3, 2-deoxyglucose, and acetylsalicylic acid. Specifically, effectiveness of these agents to attenuate the level of constitutive mTOR signaling was tested by cytometry and confirmed by Western blotting through measuring phosphorylation of the mTOR-downstream targets including ribosomal protein S6. The ratiometric analysis of phosphorylated to total protein along the mTOR pathway offers a useful parameter reporting the effects of gero-suppressive agents. In parallel, their ability to suppress the level of constitutive DNA damage signaling induced by endogenous ROS was measured. While the primary target of each of these agents may be different the data obtained on several human cancer cell lines, WI-38 fibroblasts and normal lymphocytes suggest common downstream mechanism in which the decline in mTOR/S6K1 signaling and translation rate is coupled with a reduction of oxidative phosphorylation and ROS that leads to decreased oxidative DNA damage. The combined assessment of constitutive γH2AX expression, mitochondrial activity (ROS, ΔΨm), and mTOR signaling provides an adequate gamut of cell responses to test effectiveness of gero-suppressive agents. Described is also an in vitro model of induction of cellular senescence by persistent replication stress, its quantitative analysis by laser scanning cytometry, and application to detect the property of the studied agents to attenuate the induction of senescence. Discussed is cytometric analysis of cell size and heterogeneity of size as a potential biomarker used to asses gero-suppressive agents and longevity.

Antidiabetic Drug Metformin Prevents Progression of Pancreatic Cancer by Targeting in Part Cancer Stem Cells and mTOR Signaling

Epidemiologic studies have shown that diabetes mellitus is associated positively with increased risk of pancreatic ductal adenocarcinoma (PDAC), and recent meta-analysis studies showed that metformin, reduces the risk of pancreatic cancer (PC). We tested the effects of metformin on pancreatic intraepithelial neoplasia (PanIN) and their progression to PDAC in p48Cre/+.LSL-KrasG12D/+ transgenic mice. Mice fed control diet showed 80% and 62% incidence of PDAC in males and females, respectively. Male mice showed 20% and 26%, and female mice showed 7% and 0% PDAC incidence with 1000- and 2000-ppm metformin treatments, respectively. Both doses of metformin decreased pancreatic tumor weights by 34% to 49% (P < 0.03-0.001). The drug treatment caused suppression of PanIN 3 (carcinoma in situ) lesions by 28% to 39% (P < .002) and significant inhibition of carcinoma spread in the pancreas. The pancreatic tissue and/or serum of mice fed metformin showed a significant inhibition of mammalian target of rapamycin (mTOR), extracellular signal-regulated kinases (ERK), phosphorylated extracellular signal-regulated kinases (pErk), and insulin-like growth factor 1 (IGF-1) with an increase in phosphorylated 5' adenosine monophosphate kinase (pAMPK), tuberous sclerosis complex 1 (TSC1, TSC2), C-protein and an autophagy related protein 2 (ATG2). The cancer stem cell (CSC) markers were significantly decreased (P < 0.04-0.0002) in the pancreatic tissue. These results suggest that biologic effects of metformin are mediated through decreased CSC markers cluster of differentiation 44 (CD44 and CD133), aldehyde dehydrogenase isoform 1 (ALDH1), and epithelial cell adhesion molecule (EPCAM) and modulation of the mTOR signaling pathway. Our preclinical data indicate that metformin has significant potential for use in clinical trials for PC chemoprevention.

Potential anti-aging agents suppress the level of constitutive mTOR- and DNA damage- signaling

Two different mechanisms are considered to be the primary cause of aging. Cumulative DNA damage caused by reactive oxygen species (ROS), the by-products of oxidative phosphorylation, is one of these mechanisms (ROS concept). Constitutive stimulation of mitogen- and nutrient-sensing mTOR/S6 signaling is the second mechanism (TOR concept). The flow- and laser scanning- cytometric methods were developed to measure the level of the constitutive DNA damage/ROS- as well as of mTOR/S6- signaling in individual cells. Specifically, persistent activation of ATM and expression of γH2AX in untreated cells appears to report constitutive DNA damage induced by endogenous ROS. The level of phosphorylation of Ser235/236-ribosomal protein (RP), of Ser2448-mTOR and of Ser65-4EBP1, informs on constitutive signaling along the mTOR/S6 pathway. Potential gero-suppressive agents rapamycin, metformin, 2-deoxyglucose, berberine, resveratrol, vitamin D3 and aspirin, all decreased the level of constitutive DNA damage signaling as seen by the reduced expression of γH2AX in proliferating A549, TK6, WI-38 cells and in mitogenically stimulated human lymphocytes. They all also decreased the level of intracellular ROS and mitochondrial trans-membrane potential ΔΨm, the marker of mitochondrial energizing as well as reduced phosphorylation of mTOR, RP-S6 and 4EBP1. The most effective was rapamycin. Although the primary target of each on these agents may be different the data are consistent with the downstream mechanism in which the decline in mTOR/S6K signaling and translation rate is coupled with a decrease in oxidative phosphorylation, (revealed by ΔΨm) that leads to reduction of ROS and oxidative DNA damage. The decreased rate of translation induced by these agents may slow down cells hypertrophy and alleviate other features of cell aging/senescence. Reduction of oxidative DNA damage may lower predisposition to neoplastic transformation which otherwise may result from errors in repair of DNA sites coding for oncogenes or tumor suppressor genes. The data suggest that combined assessment of constitutive γH2AX expression, mitochondrial activity (ROS, ΔΨm) and mTOR signaling provides an adequate gamut of cell responses to evaluate effectiveness of gero-suppressive agents.

Berberine suppresses gero-conversion from cell cycle arrest to senescence

Berberine (BRB), a natural alkaloid, has a long history of medicinal use in both Ayurvedic and old Chinese medicine. Recently, available as a dietary supplement, Berberine is reported to have application in treatment of variety diseases. Previously we observed that BRB inhibited mTOR/S6 signaling concurrently with reduction of the level of endogenous oxidants and constitutive DNA damage response. We currently tested whether Berberine can affect premature, stress-induced cellular senescence caused by mitoxantrone. The depth of senescence was quantitatively measured by morphometric parameters, senescence-associated β-galactosidase, induction of p21WAF1, replication stress (γH2AX expression), and mTOR signaling; the latter revealed by ribosomal S6 protein (rpS6) phosphorylation. All these markers of senescence were distinctly diminished, in a concentration-dependent manner, by Berberine. In view of the evidence that BRB localizes in mitochondria, inhibits respiratory electron chain and activates AMPK, the observed attenuation of the replication stress-induced cellular senescence most likely is mediated by AMPK that leads to inhibition of mTOR signaling. In support of this mechanism is the observation that rhodamine123, the cationic probe targeting mitochondrial electron chain, also suppressed rpS6 phosphorylation. The present findings reveal that: (a) in cells induced to senescence BRB exhibits gero-suppressive properties by means of mTOR/S6 inhibition; (b) in parallel, BRB reduces the level of constitutive DNA damage response, previously shown to report oxidative DNA damage by endogenous ROS; (c) there appears to a causal linkage between the (a) and (b) activities; (d) the in vitro model of premature stress-induced senescence can be used to assess effectiveness of potential gero-suppressive agents targeting mTOR/S6 and ROS signaling; (e) since most of the reported beneficial effects of BRB are in age-relate diseases, it is likely that gero-suppression is the primary activity of this traditional medicine.

Association between baseline body mass index and overall survival among patients over age 60 with acute myeloid leukemia

Acute myeloid leukemia (AML) is more common and more lethal among patients over the age of 60. Increased body mass index (BMI) has been associated with a higher incidence of various malignancies, including AML. We sought to determine whether patient BMI at the time of AML diagnosis is related to overall survival (OS) among elderly patients. We identified 97 patients with AML diagnosed after the age of 60 and treated with cytarabine-based induction chemotherapy. The median age was 68 years (range 60-87); 52% of patients were male, and our study population was predominantly white (89% of patients). The median OS for all patients was 316 days (95% CI 246-459). The hazard ratio for mortality was increased among patients with a BMI < 25 compared to BMI ≥ 30 (HR 2.14, P = 0.009, 95% CI 1.21-3.77), as well as with older age (HR 1.76, P = 0.015, 95% CI 1.12-2.79) and with secondary versus de novo disease (HR 1.95, P = 0.006, 95% CI 1.21-3.14). After multivariable analysis, we did not find a significant association between OS and other potential confounders such as coronary artery disease or diabetes among these patients. We conclude that increased BMI was independently associated with improved OS among older AML patients at our institution.

K‑ras gene mutation as a predictor of cancer cell responsiveness to metformin

An increasing number of studies support the use of metformin, a common antidiabetic drug, as a novel anticancer therapeutic. However, its mechanism of action has yet to be identified. In the current study, metformin was observed to effectively inhibit the growth of the K-ras mutant but not wild-type tumors in vivo. The antitumor effects of metformin were mediated by the induction of apoptosis and inhibition of proliferation in vivo. In addition, metformin induced apoptosis in the K-ras mutant tumors, A549 and PANC-1, but not in the K-ras wild-type tumor, A431, in vitro. Similarly, at lower concentrations, metformin inhibited cell proliferation in the K-ras mutant, but not in the K-ras wild-type tumor cells in vitro. These observations indicate that tumors with K-ras mutations are sensitive to metformin therapy. In addition, metformin significantly arrested K-ras mutant and wild-type tumor cells in G1 phase in vitro and metformin downregulated two important downstream effectors of the Ras signaling pathway in K-ras mutant tumors. Metformin was concluded to function as a potential K-ras-targeting agent that has potential for cancer therapy.

Metformin, at concentrations corresponding to the treatment of diabetes, potentiates the cytotoxic effects of carboplatin in cultures of ovarian cancer cells

The use of the type 2 diabetics drug metformin has been correlated with enhanced progression-free survival in ovarian cancer. The literature has speculated that this enhancement is due to the high concentration of metformin directly causing cancer cell death. However, this explanation does not fit with clinical data reporting that the women exposed to constant micromolar concentrations of metformin, as present in the treatment of diabetes, respond better to chemotherapy. Herein, our aim was to examine whether micromolar concentrations of metformin alone could bring about cancer cell death and whether micromolar metformin could increase the cytotoxic effect of commonly used chemotherapies in A2780 and SKOV3 cell lines and primary cultured cancer cells isolated from the peritoneal fluid of patients with advanced ovarian cancer. Our results in cell lines demonstrate that no significant loss of viability or change in cell cycle was observed with micromolar metformin alone; however, we observed cytotoxicity with micromolar metformin in combination with chemotherapy at concentrations where the chemotherapy alone produced no loss in viability. We demonstrate that previous exposure and maintenance of metformin in conjunction with carboplatin produces a synergistic enhancement in cytotoxicity of A2780 and SKOV3 cells (55% and 43%, respectively). Furthermore, in 5 (44%) of the 11 ovarian cancer primary cultures, micromolar metformin improved the cytotoxic response to carboplatin but not paclitaxel or doxorubicin. In conclusion, we present data that support the need for a clinical study to evaluate the adjuvant maintenance or prescription of currently approved doses of metformin during the chemotherapeutic treatment of ovarian cancer.

Unraveling the mystery of cancer metabolism in the genesis of tumor-initiating cells and development of cancer

Robust anaerobic metabolism plays a causative role in the origin of cancer cells; however, the oncogenic metabolic genes, factors, pathways, and networks in genesis of tumor-initiating cells (TICs) have not yet been systematically summarized. In addition, the mechanisms of oncogenic metabolism in the genesis of TICs are enigmatic. In this review, we discussed multiple cancer metabolism-related genes (MRGs) that are overexpressed in TICs and are responsible for inducing pluripotent stem cells. Moreover, we summarized that oncogenic metabolic genes and onco-metabolites induce metabolic reprogramming, which switches normal mitochondrial oxidative phosphorylation to cancer anaerobic metabolism, triggers epigenetic, genetic, and environmental alterations, drives the generation of TICs, and boosts the development of cancer. Importantly, cancer metabolism is controlled by positive and negative metabolic regulators. Positive oncogenic metabolic regulators, including key oncogenic metabolic genes, onco-metabolites, hypoxia, and an acidic environment, promote oncogenic metabolic reprogramming and anaerobic metabolism. However, dysfunction of negative metabolic regulators, including defects in p53, PTEN, and LKB1-AMPK-mTOR pathways, enhances cancer metabolism. Loss of the metabolic balance results in oncogenic metabolic reprogramming, genesis of TICs, and tumorigenesis. Collectively, this review provides new insight into the role and mechanism of these oncogenic metabolisms in the genesis of TICs and tumorigenesis. Accordingly, targeting key oncogenic genes, onco-metabolites, pathways, networks, and the acidic cancer microenvironment appears to be an attractive strategy for novel anti-tumor treatment.

Epithelial cell polarity: what flies can teach us about cancer

Epithelial cells are polarized along their apical-basal axis. Much of the cellular machinery that goes into establishing and maintaining epithelial cell polarity is evolutionarily conserved. Model organisms, including the fruit fly, Drosophila melanogaster, are thus particularly useful for the study of cell polarity. Work in Drosophila has identified several important components of the polarity machinery and has also established the surprising existence of a secondary cell polarity pathway required only under conditions of energetic stress. This work has important implications for the understanding of human cancer. Most cancers are epithelial in origin, and the loss of cell polarity is a critical step towards malignancy. Thus a better understanding of how polarity is established and maintained in epithelial cells will help us to understand the process of malignant transformation and may lead to improved therapies. In the present chapter we discuss the current understanding of how epithelial cell polarity is regulated and the known associations between polarity factors and cancer.

Pigment epithelium-derived factor increases in type 2 diabetes after treatment with metformin

OBJECTIVE

Pigment epithelium-derived factor (PEDF) has anti-angiogenic, immunomodulatory and anti-inflammatory properties. In addition to the significant role it plays in reducing diabetic complications, PEDF is now used in the treatment of certain cancers. It possibly plays a role in insulin resistance cases, too. However, whether metformin treatment has any significant effects on PEDF levels is not known. In this study, we investigated the regulation of PEDF in type 2 diabetes in relation to fat mass and insulin resistance before and after the use of metformin for treatment.

DESIGN

Prospective cohort study.

SUBJECTS

Thirty-six patients with newly diagnosed type 2 diabetes and 33 healthy individuals.

MEASUREMENTS

Baseline weight, waist circumference (WC), fasting (FPG) and postprandial (PPPG) glucose, insulin, HbA1c, HOMA, PEDF and total/truncal fat mass were determined both in the diabetic and control subjects. Procedures were repeated in the diabetic group after a 6-month metformin treatment.

RESULTS

Baseline FPG, PPPG, HbA1c, HOMA, weight, WC and truncal fat mass were higher in patients with diabetes whereas PEDF levels were found to be comparable with the controls. We completed the study with 31 of the 36 patients with diabetes we had selected for the study. We observed a decrease in the weight, WC, FPG, PPPG, HOMA, total and truncal fat mass of the patients while there was a significant rise in the PEDF levels (P = 0·002) after the metformin treatment. On the other hand, no significant correlation was observed between the change in PEDF levels and the clinical and laboratory findings.

CONCLUSION

Our study is the first to identify a metformin-related increase in PEDF levels in diabetes. The increase observed in PEDF levels after the metformin treatment does not seem to be related to the changes in insulin resistance, fat mass or glycemic control. Hence, our results suggest that further investigation is necessary to determine the direct effects of metformin on PEDF gene and protein expression in vitro.

Dietary intervention in acne: Attenuation of increased mTORC1 signaling promoted by Western diet

The purpose of this paper is to highlight the endocrine signaling of Western diet, a fundamental environmental factor involved in the pathogenesis of epidemic acne. Western nutrition is characterized by high calorie uptake, high glycemic load, high fat and meat intake, as well as increased consumption of insulin- and IGF-1-level elevating dairy proteins. Metabolic signals of Western diet are sensed by the nutrient-sensitive kinase, mammalian target of rapamycin complex 1 (mTORC1), which integrates signals of cellular energy, growth factors (insulin, IGF-1) and protein-derived signals, predominantly leucine, provided in high amounts by milk proteins and meat. mTORC1 activates SREBP, the master transcription factor of lipogenesis. Leucine stimulates mTORC1-SREBP signaling and leucine is directly converted by sebocytes into fatty acids and sterols for sebaceous lipid synthesis. Over-activated mTORC1 increases androgen hormone secretion and most likely amplifies androgen-driven mTORC1 signaling of sebaceous follicles. Testosterone directly activates mTORC1. Future research should investigate the effects of isotretinoin on sebocyte mTORC1 activity. It is conceivable that isotretinoin may downregulate mTORC1 in sebocytes by upregulation of nuclear levels of FoxO1. The role of Western diet in acne can only be fully appreciated when all stimulatory inputs for maximal mTORC1 activation, i.e., glucose, insulin, IGF-1 and leucine, are adequately considered. Epidemic acne has to be recognized as an mTORC1-driven disease of civilization like obesity, type 2 diabetes, cancer and neurodegenerative diseases. These new insights into Western diet-mediated mTORC1-hyperactivity provide a rational basis for dietary intervention in acne by attenuating mTORC1 signaling by reducing (1) total energy intake, (2) hyperglycemic carbohydrates, (3) insulinotropic dairy proteins and (4) leucine-rich meat and dairy proteins. The necessary dietary changes are opposed to the evolution of industrialized food and fast food distribution of Westernized countries. An attenuation of mTORC1 signaling is only possible by increasing the consumption of vegetables and fruit, the major components of vegan or Paleolithic diets. The dermatologist bears a tremendous responsibility for his young acne patients who should be advised to modify their dietary habits in order to reduce activating stimuli of mTORC1, not only to improve acne but to prevent the harmful and expensive march to other mTORC1-related chronic diseases later in life.

Metformin, an antidiabetic agent reduces growth of cutaneous squamous cell carcinoma by targeting mTOR signaling pathway

The biguanide metformin is widely used for the treatment of Type-II diabetes. Its antiproliferative and pro-apoptotic effects in various tumor cells suggest its potential candidacy for cancer chemoprevention. Herein, we report that metformin significantly inhibited human epidermoid A431 tumor xenograft growth in nu/nu mice, which was associated with a significant reduction in proliferative biomarkers PCNA and cyclins D1/B1. This tumor growth reduction was accompanied by the enhanced apoptotic cell death and an increase in Bax:Bcl2 ratio. The mechanism by which metformin manifests antitumor effects appears to be dependent on the inhibition of nuclear factor kappa B (NFkB) and mTOR signaling pathways. Decreased phosphorylation of NFkB inhibitory protein IKBα together with reduced enhancement of NFkB transcriptional target proteins, iNOS/COX-2 were observed. In addition, a decrease in the activation of ERK/p38-driven MAP kinase signaling was seen. Similarly, AKT signaling activation as assessed by the diminished phosphorylation at Ser473 with a concomitant decrease in mTOR signaling pathway was also noted as phosphorylation of mTOR regulatory proteins p70S6K and 4E-BP-1 was significantly reduced. Consistently, decreased phosphorylation of GSK3β, which is carried out by AKT kinases was also observed. These results suggest that metformin blocks SCC growth by dampening NFkB and mTOR signaling pathways.

AMPK in BCR-ABL expressing leukemias. Regulatory effects and therapeutic implications

The abnormal BCR-ABL oncoprotein is a constitutively active tyrosine kinase driving aberrant proliferation of transformed hematopoietic cells. BCR-ABL regulates activation of many mitogenic and pro-survival pathways, including the PI 3'K/AKT/mTOR pathway that controls various effectors and regulates initiation of mRNA translation in mammalian cells. Although tyrosine kinase inhibitors (TKIs) that target the ABL kinase domain have remarkable clinical activity and have dramatically changed the natural history of Ph+ leukemias, resistance to these agents also develops via a wide range of mechanisms. Efforts to target the PI3'K/AKT/mTOR signaling pathway using kinase inhibitors have been the focus of extensive ongoing investigations by several research groups. Here we review the effects of activation of the AMPK kinase, which regulates downstream targeting and inhibition of mTOR. The potential for future clinical-translational applications of AMPK activators such as AICAR, metformin and resveratrol for the treatment of chronic myelogenous leukemia (CML) and Ph+ acute lymphoblastic leukemia (ALL) are discussed.

Antidiabetic drug metformin suppresses endotoxin-induced uveitis in rats

PURPOSE

To investigate the therapeutic effects of metformin, a commonly used antidiabetic drug, in preventing endotoxin-induced uveitis (EIU) in rats.

METHODS

EIU in Lewis rats was developed by subcutaneous injection of lipopolysaccharide (LPS; 150 μg). Metformin (300 mg/kg body weight, intraperitoneally) or its carrier was injected either 12 hours before or 2 hours after LPS induction. Three and 24 hours after EIU, eyes were enucleated and aqueous humor (AqH) was collected. The MILLIPLEX-MAG Rat cytokine-chemokine magnetic bead array was used to determine inflammatory cytokines. The expression of Cox-2, phosphorylation of AMPK, and NF-κB (p65) were determined immunohistochemically. Primary human nonpigmented ciliary epithelial cells (HNPECs) were used to determine the in vitro efficacy of metformin.

RESULTS

Compared with controls, the EIU rat AqH had significantly increased number of infiltrating cells and increased levels of various cytokines and chemokines (TNF-α, MCP-1, IL-1β, MIP-1α, IL-6, Leptin, and IL-18) and metformin significantly prevented the increase. Metformin also prevented the expression of Cox-2 and phosphorylation of p65, and increased the activation of AMPK in the ciliary bodies and retinal tissues. Moreover, metformin prevented the expression of Cox-2, iNOS, and activation of NF-kB in the HNPECs and decreased the levels of NO and PGE2 in cell culture media.

CONCLUSIONS

Our results for the first time demonstrate a novel role of the antidiabetic drug, metformin, in suppressing uveitis in rats and suggest that this drug could be developed to prevent uveitis complications.

Association of thiazolidinediones with liver cancer and colorectal cancer in type 2 diabetes mellitus

The objective of this nationwide case-control study was to evaluate the risk of specific malignancy in diabetic patients who received thiazolidinediones (TZDs). A total of 606,583 type 2 diabetic patients, age 30 years and above, without a history of cancer were identified from the Taiwan National Health Insurance claims database during the period between January 1 2000 and December 31 2000. As of December 31 2007, patients with incident cancer of liver, colorectal, lung, and urinary bladder were included as cases and up to four age- and sex-matched controls were selected by risk-set sampling. Logistic regression models were applied to estimate the odds ratio (OR) and 95% confidence interval (CI) between TZDs and cancer incidence. A total of 10,741 liver cancer cases, 7,200 colorectal cancer cases, and 70,559 diabetic controls were included. A significantly lower risk of liver cancer incidence was found for any use of rosiglitazone (OR: 0.73, 95% CI: 0.65-0.81) or pioglitazone (OR: 0.83, 95% CI: 0.72-0.95), respectively. The protective effects were stronger for higher cumulative dosage and longer duration. For colorectal cancer, rosiglitazone, but not pioglitazone, was associated with a significantly reduced risk (OR: 0.86; 95% CI: 0.76-0.96). TZDs were not associated with lung and bladder cancer incidence, although a potential increased risk for bladder cancer with pioglitazone use ≥3 years could not be excluded (OR: 1.56; 95% CI: 0.51-4.74).

CONCLUSION

The use of pioglitazone and rosiglitazone is associated with a decreased liver cancer incidence in diabetic patients. The effects on occurrence of specific cancer types may be different for pioglitazone and rosiglitazone.

Metformin use is associated with better survival of diabetic patients with pancreatic cancer

PURPOSE

Accumulating evidence suggests that metformin has antitumor activity. The aim of this study was to determine whether metformin use has a survival benefit in patients with pancreatic cancer.

EXPERIMENTAL DESIGN

We conducted a retrospective study of patients with diabetes and pancreatic cancer treated at The University of Texas MD Anderson Cancer Center (Houston, TX). Information on diabetes history, including treatment modalities and clinical outcome of pancreatic cancer, was collected using personal interviews and medical record review. Survival analysis was carried out using a Kaplan-Meier plot, log-rank test, and Cox proportional hazards regression models.

RESULTS

Among the 302 patients identified, there were no significant differences in demographic or major clinical characteristics between the patients who had received metformin (n = 117) and those who had not (n = 185). The 2-year survival rate was 30.1% for the metformin group and 15.4% for the non-metformin group (P = 0.004; χ(2) test). The median overall survival time was 15.2 months for the metformin group, and 11.1 months for the non-metformin group (P = 0.004, log-rank test). Metformin users had a 32% lower risk of death; the HR (95% confidence interval) was 0.68 (0.52-0.89) in a univariate model (P = 0.004), 0.64 (0.48-0.86) after adjusting for other clinical predictors (P = 0.003), and 0.62 (0.44-0.87) after excluding insulin users (P = 0.006). Metformin use was significantly associated with longer survival in patients with nonmetastatic disease only.

CONCLUSIONS

Our finding that metformin use was associated with improved outcome of patients with diabetes and pancreatic cancer should be confirmed in independent studies. Future research should prospectively evaluate metformin as a supplemental therapy in this population.

Leucine signaling in the pathogenesis of type 2 diabetes and obesity

Epidemiological evidence points to increased dairy and meat consumption, staples of the Western diet, as major risk factors for the development of type 2 diabetes (T2D). This paper presents a new concept and comprehensive review of leucine-mediated cell signaling explaining the pathogenesis of T2D and obesity by leucine-induced over-stimulation of mammalian target of rapamycin complex 1 (mTORC1). mTORC1, a pivotal nutrient-sensitive kinase, promotes growth and cell proliferation in response to glucose, energy, growth factors and amino acids. Dairy proteins and meat stimulate insulin/insulin-like growth factor 1 signaling and provide high amounts of leucine, a primary and independent stimulator for mTORC1 activation. The downstream target of mTORC1, the kinase S6K1, induces insulin resistance by phosphorylation of insulin receptor substrate-1, thereby increasing the metabolic burden of β-cells. Moreover, leucine-mediated mTORC1-S6K1-signaling plays an important role in adipogenesis, thus increasing the risk of obesity-mediated insulin resistance. High consumption of leucine-rich proteins explains exaggerated mTORC1-dependent insulin secretion, increased β-cell growth and β-cell proliferation promoting an early onset of replicative β-cell senescence with subsequent β-cell apoptosis. Disturbances of β-cell mass regulation with increased β-cell proliferation and apoptosis as well as insulin resistance are hallmarks of T2D, which are all associated with hyperactivation of mTORC1. In contrast, the anti-diabetic drug metformin antagonizes leucine-mediated mTORC1 signaling. Plant-derived polyphenols and flavonoids are identified as natural inhibitors of mTORC1 and exert anti-diabetic and anti-obesity effects. Furthermore, bariatric surgery in obesity reduces increased plasma levels of leucine and other branched-chain amino acids. Attenuation of leucine-mediated mTORC1 signaling by defining appropriate upper limits of the daily intake of leucine-rich animal and dairy proteins may offer a great chance for the prevention of T2D and obesity, as well as other epidemic diseases of civilization with increased mTORC1 signaling, especially cancer and neurodegenerative diseases, which are frequently associated with T2D.