The anti-diabetic drug metformin inhibits vascular endothelial growth factor expression via the mammalian target of rapamycin complex 1/hypoxia-inducible factor-1α signaling pathway in ELT-3 cells

Metformin in gynecological disorders: pathogenic insights and therapeutic implications

Metformin, the most widely used anti-diabetic drug, has been demonstrated to exert various effects, including antioxidant, anti-inflammatory, anti-tumor, and cardioprotective properties. Due to its affordability and low toxicity profile, metformin is increasingly used to prevent or treat a wide range of gynecological disorders, as evidenced by epidemiological studies, clinical trials, and animal and in vitro studies. Trial findings for non-cancer conditions such as endometriosis, premature ovarian failure (POF), and uterine fibroids remain controversial and insufficient. However, most current clinical trials for polycystic ovarian syndrome (PCOS) and gynecological malignancies are ongoing phase II-III trials. The pharmacological effects of metformin have been shown to target the insulin-like growth factor (IGF), AMP-activated protein kinase (AMPK), phosphatidylinositol 3-kinase (PI3K)/AKT, MAPK, NF-κB, and other signal transduction pathways, highlighting its potential in the treatment of gynecological disorders. In this review, we discuss the biological impacts of metformin and the mechanisms of action pertinent to the treatment of different gynecological disorders.

Neratinib and metformin: A novel therapeutic approach against HER2-Positive Breast Cancer

BACKGROUND

HER2-positive breast cancer (BC) is highly aggressive with a poor prognosis. It is driven by HER2 oncoprotein activation/crosstalk with other receptors like EGFR/(HER1), HER3, and HER4, in addition to IGF-1R, making these receptors ideal therapeutic targets as they are expressed/overexpressed in this subtype. We postulated that targeting HER2 and IGF-1R together is a promising therapy for HER2-positive BC. Thus, we explored the outcome of a novel combination treatment using neratinib, a pan-HER inhibitor, and metformin, an IGF-1R inhibitor, on HER2-positive BC cells.

METHODS

In this investigation, we used cellular and molecular biology techniques in addition to an angiogenesis model and tissue microarray analysis.

RESULTS

Our data revealed that this combination therapy significantly reduced cell viability compared to individual treatments and exhibited a synergistic effect in HER2-positive BC cells. Moreover, the combination disrupted cell cycle progression and inhibited colony formation, and invasion of HER2-positive BC cells; this is accompanied by the deregulation of HER1-3 and IGF-1R expression patterns, in addition to Caspase-3, BCL2, Fascin, and Vimentin. Moreover, key regulator molecular pathways, including, ERK1/2, AKT, p38 MAPK, and mTOR, were significantly downregulated upon treatment with neratinib and metformin combination. Additionally, our data pointed out that neratinib and metformin combination inhibited angiogenesis, in-ovo, an important biological event in cancer progression. Finally, using a cohort of 55 HER2-positive BC samples, we revealed that HER2 and IGF-1R are co-expressed in most of the cases.

CONCLUSIONS

These findings suggest that neratinib and metformin combination can present a promising strategy for targeting multiple pathways in HER2-positive BC.

Metformin and the PI3K/AKT signaling pathway: implications for cancer, cardiovascular, and central nervous system diseases

Recent findings have brought our understanding of diseases at the molecular level, highlighting upstream intracellular pathways as potential therapeutic targets. The PI3K/AKT pathway, a key regulator of cellular responses to environmental changes, is frequently altered in various diseases, making it a promising target for intervention. Metformin is the most known anti-diabetic agent that is known due to its effects on cancer, inflammatory-related diseases, oxidative stress, and other human diseases. It is clearly understood that metformin modulates the activity of the PI3K/AKT pathway leading to a wide variety of outcomes. This interaction has been well-studied in various diseases. Therefore, this review aims to examine PI3K/AKT-modulating properties of metformin in cancer, cardiovascular, and central nervous system diseases. Our findings indicate that metformin is effective in treating cancer and CNS diseases, and plays a role in both the prevention and treatment of cardiovascular diseases. These insights support the potential of metformin in comprehensive strategies for disease management.

Progestin-based pharmacotherapy in fertility preservation in early endometrial cancer

Endometrial cancer is a common tumor of the female reproductive system. In recent years, as the age of onset of the disease has gradually become younger, this has caused distress to some young patients with reproductive needs, and the active search for methods of preserving reproductive function has gradually attracted attention. In this paper, we will systematize the current status of progestin-based pharmacotherapy in combination with other drug therapies in the conservative management of early-stage endometrial cancer. With the expectation of providing a reference for the treatment of early stage endometrial cancer patients in China and for the in-depth development of related research in this field.

Findings on Age at Onset of Cancer in Diabetic and Non-diabetic Populations

Background Diabetes mellitus and cancer are two associated chronic diseases. Despite being a widely researched topic, the underlying mechanisms of this association remain unclear. One of the poorly explored topics regarding diabetes and cancer is the relation between the age of cancer onset and diabetes mellitus status; therefore, this research exposes the difference in the age of cancer diagnosis in both groups. Methods We conducted a retrospective study by reviewing the clinical files on a secondary care hospital's database. Files from first-time consultations of patients over 18 diagnosed using a histopathological report were included. The present study aimed to determine whether there is a difference in age at the onset of cancer in diabetic and non-diabetic individuals. Moreover, we calculated the average BMI at the onset for both populations. Results Our study included 8,741 patients; 1,551 (17.8%) were diabetic, and 7,190 (82.2%) were non-diabetic. From 28 types of cancer, 27 showed a difference in the age at the onset of cancer when diabetic and non-diabetic subjects were compared. This difference is significant as it suggests a potential link between diabetes and cancer, which could have implications for early detection and prevention strategies. Out of the 27 types, 17 showed statistical significance with p-values ranging from 0.048 to <0.0001 considering a 95% CI. Among those, the most significant types of cancer were breast, cervical, lung, ovarian, rectal, thyroid, and sarcoma, reporting p-values <0.0001. The mean age at onset of cancer in diabetic and non-diabetic populations was 62.7 years (SD ± 3.9) and 55.3 years (SD ± 7.9), respectively, showing a difference of 7.4 years in both groups. The BMI was statistically significant in patients with breast (p = 0.006), endometrial (p = 0.007), head and neck (p=0.014), and thyroid (p = 0.022) cancer types. Conclusion  The data offer a critical view of the relationship between cancer and diabetes. Since virtually no one has produced a similar report, there is a broad field for researching the causal factors implicated in the pathway of diabetic and non-diabetic individuals who develop cancer. Research regarding metformin, diabetic neuropathy, and other possible causes must be addressed to determine whether they are involved in this process.

The Anti-Diabetic Drug Metformin Suppresses Pathological Retinal Angiogenesis via Blocking the mTORC1 Signaling Pathway in Mice (Metformin Suppresses Pathological Angiogenesis)

PURPOSE

Metformin, a biguanide antihyperglycemic drug, can exert various beneficial effects in addition to its glucose-lowering effect. The effects of metformin are mainly mediated by AMP-activated protein kinase (AMPK)-dependent pathway. AMPK activation interferes with the action of the mammalian target of rapamycin complex 1 (mTORC1), and blockade of mTORC1 pathway suppresses pathological retinal angiogenesis. Therefore, in this study, we examined the effects of metformin on pathological angiogenesis and mTORC1 activity in the retinas of mice with oxygen-induced retinopathy (OIR).

METHODS

OIR was induced by exposing the mice to 80% oxygen from postnatal day (P) 7 to P10. The OIR mice were treated with metformin, rapamycin (an inhibitor of mTORC1), or the vehicle from P10 to P12 or P14. The formation of neovascular tufts, revascularization in the central avascular areas, expression of vascular endothelial growth factor (VEGF) and VEGF receptor (VEGFR) 2, and phosphorylated ribosomal protein S6 (pS6), a downstream indicator of mTORC1 activity, were evaluated at P10, P13, or P15.

RESULTS

Neovascular tufts and vascular growth in the central avascular areas were observed in the retinas of P15 OIR mice. The formation of neovascular tufts, but not the revascularization in the central avascular areas, was attenuated by metformin administration from P10 to P14. Metformin had no significant inhibitory effect on the expression of VEGF and VEGFR2, but it reduced the pS6 immunoreactivity in vascular cells at the sites of angiogenesis. Rapamycin completely blocked the phosphorylation of ribosomal protein S6 and markedly reduced the formation of neovascular tufts.

CONCLUSIONS

These results suggest that metformin partially suppresses the formation of neovascular tufts on the retinal surface by blocking the mTORC1 signaling pathway. Metformin may exert beneficial effects against the progression of ocular diseases in which abnormal angiogenesis is associated with the pathogenesis.

Metformin: A Potential Treatment for Acne, Hidradenitis Suppurativa and Rosacea

Metformin is a widely used drug for treatment of diabetes mellitus, due to its safety and efficacy. In addition to its role as an antidiabetic drug, numerous beneficial effects of metformin have enabled its use in various diseases. Considering the anti-androgenic, anti-angiogenic, anti-fibrotic and antioxidant properties of metformin, it may have the potential to improve chronic inflammatory skin diseases. However, further evidence is needed to confirm the efficacy of metformin in dermatological conditions, This review focuses on exploring the therapeutic targets of metformin in acne vulgaris, hidradenitis suppurativa and rosacea, by studying their pathogeneses.

Metformin-induced AMPK activation promotes cisplatin resistance through PINK1/Parkin dependent mitophagy in gastric cancer

Gastric cancer (GC) is one of the most common tumors worldwide, and cisplatin is a standard chemotherapeutic reagent for GC treatment. However, chemoresistance is an inherent challenge which limits its application and effectiveness in clinic. This study aims to investigate the mechanism of metformin-induced cisplatin resistance in GC. Intriguingly, the upregulation of mitophagy markers, mitochondrial fission, autophagy and mitophagosome were observed in SGC-7901/DDP cells compared to those in the SGC-7901 cells. Treatment with metformin significantly increased mitochondrial fission and mitophagy in both AGS and SGC-7901 cells, resulting in decreased ATP production, which unexpectedly protected GC cells against the cytotoxicity of cisplatin. In contrast, application of Chloroquine and 3-methyladenine, two inhibitors of autophagy, significantly alleviated the protective effect of metformin on SGC-7901 and AGS cells against cytotoxicity of cisplatin. Moreover, metformin also stimulated the phosphorylation of AMPK (Thr172) and increased the expression of mitophagy markers including Parkin and PINK1 in the AMPK signaling-dependent manner. Consistently, the cell viability and cell apoptosis assay showed that metformin-induced cisplatin resistance was prevented by knockdown of AMPKα1. Taken together, all data in this study indicate that metformin induced AMPK activation and PINK1/Parkin dependent mitophagy, which may contribute to the progression of cisplatin resistance in GC.

Diabetes Mellitus Promotes the Development of Atherosclerosis: The Role of NLRP3

Atherosclerosis is one of the main complications of diabetes mellitus, involving a variety of pathogenic factors. Endothelial dysfunction, inflammation, and oxidative stress are hallmarks of diabetes mellitus and atherosclerosis. Although the ability of diabetes to promote atherosclerosis has been demonstrated, a deeper understanding of the underlying biological mechanisms is critical to identifying new targets. NLRP3 plays an important role in both diabetes and atherosclerosis. While the diversity of its activation modes is one of the underlying causes of complex effects in the progression of diabetes and atherosclerosis, it also provides many new insights for targeted interventions in metabolic diseases.

Black cohosh efficacy and safety for menopausal symptoms. The Spanish Menopause Society statement

OBJECTIVE

The increasing interest in Western countries regarding phytotherapy use to treat menopause-related symptoms has led the Spanish Menopause Society (AEEM) to update its position statement performed in 2009 on the role of black cohosh (Cimicifuga racemosa) for the treatment of menopausal symptoms.

MATERIAL AND METHODS

A panel of experts from both clinical and research backgrounds were assembled to investigate the best available evidence. Selected studies were obtained by an electronic search, including the Internet search engines MEDLINE-Pubmed (1997-December 2021) and the Cochrane Controlled Trials Register.

RESULTS

Most of the well-designed studies published in recent years have been conducted with the isopropanolic extract of black cohosh/C. racemosa. The most common dose is 40 mg/day capable of achieving a significant reduction in hot flushes (particularly in women with intense hot flushes) and an improvement in mood. Used at the recommended doses, C. racemose produces no significant adverse reactions.

CONCLUSION

Black cohosh is an effective and safe treatment option for the relieving of vasomotor symptoms. Finally, further clinical trials with sufficient patient enrollment and longer study follow-up are needed.

Antiproliferative effects of metformin in cellular models of pheochromocytoma

Pheochromocytomas (PCCs) are rare neuroendocrine tumors derived from adrenal medulla chromaffin cells. Malignancy and recurrence are rare but demand effective treatment. Metformin exerts antiproliferative effects in several cancer cell lines. We thus evaluated the effects of metformin on cell viability and proliferation, cellular respiration and AMPK-AKT-mTOR-HIFA proliferation pathway on a rat PCC cell line (PC12-Adh). We then addressed metformin's effects on the AMPK-AKT-mTOR-HIFA pathway on two human primary cultures: one from a VHL-mutant PCC and other from a sporadic PCC. Metformin (20 mM) inhibited PC12-Adh cell proliferation, and decreased oxygen consumption, ATP production and proton leak, in addition to loss of mitochondrial membrane potential. Further, metformin induced AMPK phosphorylation and impaired AMPK-PI3k-AKT-mTOR pathway activation. The mTOR pathway was also inhibited in human VHL-related PCC cells, however, in an AMPK-independent manner. Metformin-induced decrease of HIF1A levels was likely mediated by proteasomal degradation. Altogether our results suggest that metformin impairs PCC cellular proliferation.

Dual Blockade of Lactate/GPR81 and PD-1/PD-L1 Pathways Enhances the Anti-Tumor Effects of Metformin

Metformin is a widely used antidiabetic drug for cancer prevention and treatment. However, the overproduction of lactic acid and its inefficiency in cancer therapy limit its application. Here, we demonstrate the synergistic effects of the lactate/GPR81 blockade (3-hydroxy-butyrate, 3-OBA) and metformin on inhibiting cancer cells growth in vitro. Simultaneously, this combination could inhibit glycolysis and OXPHOS metabolism, as well as inhibiting tumor growth and reducing serum lactate levels in tumor-bearing mice. Interestingly, we observed that this combination could enhance the functions of Jurkat cells in vitro and CD8+ T cells in vivo. In addition, considering that 3-OBA could recover the inhibitory effects of metformin on PD-1 expression, we further determined the dual blockade effects of PD-1/PD-L1 and lactate/GPR81 on the antitumor activity of metformin. Our results suggested that this dual blockade strategy could remarkably enhance the anti-tumor effects of metformin, or even lead to tumor regression. In conclusion, our study has proposed a novel and robust strategy for a future application of metformin in cancer treatment.

The role of AMPK/mTOR signaling pathway in anticancer activity of metformin

Metformin (MTF) is a widely used drug for the treatment of diabetes mellitus type 2 (DM2) and frequently used as an adjuvant therapy for polycystic ovarian syndrome, metabolic syndrome, and in some cases also tuberculosis. Its protective effect on the cardiovascular system has also been described. Recently, MTF was subjected to various analyzes and studies that showed its beneficial effects in cancer treatment such as reducing cancer cell proliferation, reducing tumor growth, inducing apoptosis, reducing cancer risk in diabetic patients, or reducing likelihood of relapse. One of the MTF's mechanisms of action is the activation of adenosine-monophosphate-activated protein kinase (AMPK). Several studies have shown that AMPK/mammalian target of rapamycin (mTOR) pathway has anticancer effect in vivo and in vitro. The aim of this review is to present the anticancer activity of MTF highlighting the importance of the AMPK/mTOR pathway in the cancer process.

Association of Metformin With Volumetric Tumor Growth of Sporadic Vestibular Schwannomas

OBJECTIVE

Recent research demonstrates a potential association between metformin use and reduced sporadic vestibular schwannoma (VS) growth in patients undergoing conservative observation. The current study was designed to elucidate the effect of metformin on tumor growth in sporadic VS using volumetric analyses.

STUDY DESIGN

Retrospective cohort.

SETTING

Tertiary referral center.

PATIENTS

Patients with sporadic VS who elected initial conservative treatment with at least two serial magnetic resonance imaging (MRI) scans were included.

INTERVENTIONS

Metformin use among patients with observed sporadic VS.

MAIN OUTCOME MEASURES

Tumor growth, defined as an increase in volume of at least 20% from the initial MRI.

RESULTS

A total of 361 patients were evaluated. Thirty-four patients (9%) had a diagnosis of diabetes at baseline. Nineteen patients (5%) were taking metformin at the time of the initial MRI. Metformin use was not significantly associated with a reduced risk of volumetric tumor growth in a univariable analysis in all patients undergoing observation for VS (hazard ratio [HR] 0.75; 95% confidence intervals [CI] 0.40-1.42; p = 0.38) or within the diabetic subset (HR 0.79; 95% CI 0.34-1.83; p = 0.58). Additionally, diabetes status, insulin dependence, hemoglobin A1c value, and metformin dose were not significantly associated with volumetric tumor growth.

CONCLUSION

Despite promising initial results in several previous studies, our data suggest that metformin use does not significantly reduce the risk of volumetric tumor growth in sporadic VS.

Hypoxia and hypoxia-inducible factors promote the development of neointimal hyperplasia in arteriovenous fistula

KEY POINTS

Patients with end-stage renal failure need arteriovenous fistulas (AVF) to undergo dialysis. However, AVFs present a high rate of failure as a result of excessive venous thickness. Excessive venous thickness may be a consequence of surgical dissection and change in oxygen concentration within the venous wall. We show that venous cells adapt their metabolism and growth depending on oxygen concentration, and drugs targeting the hypoxic response pathway modulate this response in vitro. We used the same drugs on a mouse model of AVF and show that direct or indirect inhibition of the hypoxia-inducible factors (HIFs) help decrease excessive venous thickness. Hypoxia and HIFs can be targets of therapeutic drugs to prevent excessive venous thickness in patients undergoing AVF surgical creation.

ABSTRACT

Because the oxygen concentration changes in the venous wall, surrounding tissue and the blood during surgical creation of arteriovenous fistula (AVF), we hypothesized that hypoxia could contribute to AVF failure as a result of neointimal hyperplasia. We postulated that modulation of the hypoxia-inducible factors (HIF) with pharmacological compounds could promote AVF maturation. Fibroblasts [normal human fibroblasts (NHF)], smooth muscle cells [human umbilical vein smooth muscle cells (HUVSMC)] and endothelial cells [human umbilical vein endothelial cells (HUVEC)], representing the three layers of the venous wall, were tested in vitro for proliferation, cell death, metabolism, reactive oxygen species production and migration after silencing of HIF1/2-α or after treatment with deferioxamine (DFO), everolimus (Eve), metformin (Met), N-acetyl-l-cysteine (NAC) and topoisomerase I (TOPO), which modulate HIF-α stability or activity. Compounds that were considered to most probably modify intimal hyperplasia were applied locally to the vessels in a mouse model of aortocaval fistula. We showed, in vitro, that NHF and HUVSMC can adapt their metabolism and thus their growth depending on oxygen concentration, whereas HUVEC appears to be less flexible. siHIF1/2α, DFO, Eve, Met, NAC and TOPO can modulate metabolism and proliferation depending on the cell type and the oxygen concentration. In vivo, siHIF1/2α, Eve and TOPO decreased neointimal hyperplasia by 32%-50%, 7 days after treatment. Within the vascular wall, hypoxia and HIF-1/2 mediate early failure of AVF. Local delivery of drugs targeting HIF-1/2 could inhibit neointimal hyperplasia in a mouse model of AVF. Such compounds may be delivered during the surgical procedure for AVF creation to prevent early AVF failure.

Targeting Hypoxia Sensitizes TNBC to Cisplatin and Promotes Inhibition of Both Bulk and Cancer Stem Cells

Development of targeted therapies for triple-negative breast cancer (TNBC) is an unmet medical need. Cisplatin has demonstrated its promising potential for the treatment of TNBC in clinical trials; however, cisplatin treatment is associated with hypoxia that, in turn, promotes cancer stem cell (CSC) enrichment and drug resistance. Therapeutic approaches to attenuate this may lead to increased cisplatin efficacy in the clinic for the treatment of TNBC. In this report we analyzed clinical datasets of TNBC and found that TNBC patients possessed higher levels of EGFR and hypoxia gene expression. A similar expression pattern was also observed in cisplatin-resistant ovarian cancer cells. We, thus, developed a new therapeutic approach to inhibit EGFR and hypoxia by combination treatment with metformin and gefitinib that sensitized TNBC cells to cisplatin and led to the inhibition of both CD44+/CD24− and ALDH+ CSCs. We demonstrated a similar inhibition efficacy on organotypic cultures of TNBC patient samples ex vivo. Since these drugs have already been used frequently in the clinic; this study illustrates a novel, clinically translatable therapeutic approach to treat patients with TNBC.

Mitochondrial Dysfunction Inhibits Hypoxia-Induced HIF-1α Stabilization and Expression of Its Downstream Targets

mtDNA variations often result in bioenergetic dysfunction inducing a metabolic switch toward glycolysis resulting in an unbalanced pH homeostasis. In hypoxic cells, expression of the tumor-associated carbonic anhydrase IX (CAIX) is enhanced to maintain cellular pH homeostasis. We hypothesized that cells with a dysfunctional oxidative phosphorylation machinery display elevated CAIX expression levels. Increased glycolysis was observed for cytoplasmic 143B mutant hybrid (m.3243A>G, >94.5%) cells (p < 0.05) and 143B mitochondrial DNA (mtDNA) depleted cells (p < 0.05). Upon hypoxia (0.2%, 16 h), genetic or pharmacological oxidative phosphorylation (OXPHOS) inhibition resulted in decreased CAIX (p < 0.05), vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1-alpha (HIF-1α) expression levels. Reactive oxygen species (ROS) and prolyl-hydroxylase 2 (PHD2) levels could not explain these observations. In vivo, tumor take (>500 mm³) took longer for mutant hybrid xenografts, but growth rates were comparable with control tumors upon establishment. Previously, it has been shown that HIF-1α is responsible for tumor establishment. In agreement, we found that HIF-1α expression levels and the pimonidazole-positive hypoxic fraction were reduced for the mutant hybrid xenografts. Our results demonstrate that OXPHOS dysfunction leads to a decreased HIF-1α stabilization and subsequently to a reduced expression of its downstream targets and hypoxic fraction in vivo. In contrast, hypoxia-inducible factor 2-alpha (HIF-2α) expression levels in these xenografts were enhanced. Inhibition of mitochondrial function is therefore an interesting approach to increase therapeutic efficacy in hypoxic tumors.

Pigment epithelium derived factor as a novel multi-target treatment for uterine fibroids

RESEARCH QUESTION

Does recombinant pigment epithelium derived factor (PEDF) have potential in treating uterine fibroids?

DESIGN

In-vitro models that used human leiomyoma and Eker rat uterine leiomyoma (ELT-3) cell lines. The ELT-3 cell line was used to examine cellular targets after adding recombinant PEDF to the culture media. Athymic nude female mice were used as an in-vivo model. They were injected with ELT-3 cells to induce ectopic fibroid lesions, then treated with recombinant PEDF.

RESULTS

RNA expression of PEDF and its receptors was found in both leiomyoma cell lines, as well as the expression of PEDF receptors. Addition of recombinant PEDF to the culture medium of leiomyoma cell lines activated ERK in a time-dependent manner, induced down-regulation of vascular endothelial growth factor mRNA and protein, as well as the mRNAs of oestrogen receptors alpha and beta and inhibited cellular proliferation. Treatment of mice-bearing fibroids with recombinant PEDF reduced fibroid growth rate and resulted in smaller tumours.

CONCLUSIONS

This study suggests that recombinant PEDF is a putative novel potent physiological treatment for uterine fibroids. It targets several cornerstones of fibroid pathobiology in parallel, including vascular endothelial growth factor and oestrogen receptors, which are needed for vascularization, and restricts fibroid growth and final size in an animal model.

Evaluation of Angiogenesis Process after Metformin and LY294002 Treatment in Mammary Tumor

BACKGROUND

The angiogenesis process is regulated by many factors, such as Hypoxia-Inducible Factor-1 (HIF-1) and Vascular Endothelial Growth Factor (VEGF). Metformin has demonstrated its ability to inhibit cell growth and the LY294002 is the major inhibitor of PI3K/AKT/mTOR pathway that has antiangiogenic properties.

METHODS

Canine mammary tumor cell lines CMT-U229 and CF41 were treated with metformin and LY294002. Cell viability, protein and gene expression of VEGF and HIF-1 were determined in vitro. For the in vivo study, CF41 cells were inoculated in female athymic nude mice treated with either metformin or LY294002. The microvessel density by immunohistochemistry for CD31 as well as the gene and protein expression of HIF-1 and VEGF were evaluated.

RESULTS

The treatment with metformin and LY294002 was able to reduce the cellular viability after 24 hours. The protein and gene expression of HIF-1 and VEGF decreased after treatment with metformin and LY294002. In the in vivo study, there was a decrease in tumor size, protein and gene expression of HIF-1 and VEGFA, in addition to the decreasing of CD31 expression after all treatments.

CONCLUSION

Our results demonstrate the effectiveness of metformin and LY294002 in controlling the angiogenesis process in mammary tumors by VEGF and HIF-1, the most important angiogenic markers.

Diabetes and its Potential Impact on Head and Neck Oncogenesis

In recent years, the incidence of diabetes mellitus and cancer has increased sharply; indeed, these have become the two most important diseases threatening health and survival. Head and neck (HN) tumors are the sixth most common malignancies in humans. Numerous studies have shown that there are many common risk factors for diabetes mellitus and HN squamous cell carcinoma, including advanced age, poor diet and lifestyle, and environmental factors. However, the mechanism linking the two diseases has not been identified. A number of studies have shown that diabetes affects the development, metastasis, and prognosis of HN cancer, potentially through the associated hyperglycemia, hyperinsulinemia and insulin resistance, or chronic inflammation. More recent studies show that metformin, the first-line drug for the treatment of type 2 diabetes, can significantly reduce the risk of HN tumor development and reduce mortality in diabetic patients. Here, we review recent progress in the study of the relationship between diabetes mellitus and HN carcinogenesis, and its potential mechanisms, in order to provide a scientific basis for the early diagnosis and effective treatment of these diseases.

Metformin use is associated with a lower risk of uterine leiomyoma in female type 2 diabetes patients

BACKGROUND

Whether metformin may reduce the risk of uterine leiomyoma in type 2 diabetes patients has not been investigated. This retrospective cohort study compared the risk of uterine leiomyoma in ever versus never users of metformin.

METHODS

Female patients with new-onset type 2 diabetes during 1999-2005 were enrolled from the reimbursement database of Taiwan's National Health Insurance and followed up from 1 January 2006 until 31 December 2011. Analyses were conducted in a propensity score (PS) matched-pair cohort of 10,998 ever users and 10,998 never users of metformin. Hazard ratios were estimated by Cox regression incorporated with the inverse probability of treatment weighting using the PS.

RESULTS

A total of 321 never users and 162 ever users developed uterine leiomyoma during follow up, with respective incidence of 704.65 and 329.82 per 100,000 person-years. The overall hazard ratio was 0.467 (95% confidence interval: 0.387-0.564). The hazard ratios for the first (<23.3 months), second (23.3-53.1 months), and third (>53.1 months) tertiles of cumulative duration were 0.881 (0.685-1.132), 0.485 (0.367-0.642), and 0.198 (0.134-0.291), respectively; and were 0.751 (0.576-0.980), 0.477 (0.360-0.632), and 0.277 (0.198-0.386), respectively, for the first (<655,000 mg), second 655,000-1,725,500 mg), and third (>1,725,500) tertiles of cumulative dose. Sensitivity analyses after excluding users of sulfonylurea, users of estrogen, users of insulin, users of incretin-based therapies during follow up, patients with irregular drug refills, patients who discontinued the use of metformin, patients who received metformin prescription less than four times, or redefining uterine leiomyoma by using 'diagnostic code' plus 'procedure codes' consistently supported a lower risk of uterine leiomyoma in ever users of metformin.

CONCLUSION

Metformin use is associated with a lower risk of uterine leiomyoma.

Systemic therapy for the treatment of endometrial cancer

Introduction: Endometrial cancer (EC) is one of the most frequent gynecological cancers worldwide. The gold standard treatment of EC is most certainly surgery and may very well be the only therapy in the early stages of disease. To improve outcomes in non-early EC, adjuvant therapy is often employed but this is not standardized. Adjuvant options can include radiotherapy, chemotherapy or a combination of both. Adjuvant chemotherapy could be indicated in high-risk stage I and II or advanced stage EC. Several clinical trials are ongoing in an attempt to define the optimal adjuvant treatment. Furthermore, chemotherapy is the front-line therapy in advanced unresectable, metastatic or recurrent endometrial cancer. Areas covered: Herein, the authors review the first-line chemotherapy for the treatment of endometrial cancer and provide their expert perspectives on these therapies. Expert opinion: Chemotherapy is fundamental in advanced/recurrent EC. Further evidence is needed to characterize the role of adjuvant chemotherapy. Future studies should consider genomic and molecular heterogeneities to identify even more efficient tailored therapies.

Incident cancer risk in dipeptidyl peptidase-4 inhibitor-treated patients with type 2 diabetes mellitus

Objective

It is known that patients with diabetes are susceptible to cancer development due to long-standing diabetic conditions. This study aimed to investigate new-onset cancer risk associated with dipeptidyl peptidase-4 (DPP-4) inhibitors as compared to metformin, the first-line antidiabetic agent with promising anticancer activity, in patients with type 2 diabetes mellitus (T2DM).

Methods

A retrospective cohort study of adult T2DM patients was performed at a tertiary care hospital in Korea. Patients who received comparison therapies during 2008–2017 were propensity score (PS)-matched in a 1:1 ratio either to the DPP-4 inhibitors group or to the metformin group in accordance with their primary antidiabetic therapy.

Results

A total of 1538 patients (769 in each group) were found eligible for study entry. Although the rate of newly diagnosed malignancy, irrespective of specific sites or types, was numerically less frequent in the DPP-4 inhibitors group, the difference in overall cancer risk between groups was not statistically significant (HR=1.00, 95% CI=0.56–1.80, P=0.998). The PS-matched patients were further stratified by relevant patient factors and diabetes severity. No signal of increased risk of malignant complications among DPP-4 inhibitor-receiving diabetic patients was detected in any of the individual strata, nor in the subgroup patients where insulin-exposed patients were excluded from study analyses in consideration of its carcinogenic properties. Patient death or incident pancreatitis events were seldom encountered in both treatment groups; hence such risks were assessed as negligible with the use of either antidiabetic therapy.

Conclusion

This PS-matched cohort study demonstrated no elevated risk of malignant complications with DPP-4 inhibitor treatment relative to metformin treatment among T2DM patients, irrespective of patient sex, age, comorbid conditions, and diabetes severity status. Similar results were confirmed in the subgroup analyses where a potential confounding effect due to the between-group disparity in insulin co-therapy was eliminated by excluding insulin-exposed patients from risk assessments.

Metformin and Breast Cancer: Molecular Targets

Metformin has been the first-line drug for the treatment of type II diabetes mellitus for decades, being presently the most widely prescribed antihyperglycemic drug. Retrospective studies associate the use of metformin with a reduction in cancer incidence and cancer-related death. However, despite extensive research about the molecular effects of metformin in cancer cells, its mode of action remains controversial. The major molecular targets of metformin include complex I of the mitochondrial electron transport chain, adenosine monophosphate (AMP)-activated protein kinase (AMPK), and mechanistic target of rapamycin complex 1 (mTORC1), but AMPK-independent effects of metformin have also been described. Breast cancer is one of the leading causes of cancer-related morbidity and mortality among women worldwide. Several studies have reinforced a link between breast cancer risk and diabetes. Moreover, metformin significantly reduces breast cancer risk, compared to patients who are not using metformin and is independent of diabetes status. In this review, we summarize the current molecular evidence to elucidate metformin's mode of action against breast cancer cells.

Pleiotropic Effects of Metformin on Cancer

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

Metformin in cancer

Metformin is a lipophilic biguanide which inhibits hepatic gluconeogenesis and improves peripheral utilization of glucose. It is the first line pharmacotherapy for glucose control in patients with Type 2 diabetes due to its safety, efficacy and tolerability. Metformin exhibits pleotropic effects, which may have beneficial effects on a variety of tissues independent of glucose control. A potential anti-tumourigenic effect of metformin may be mediated by its role in activating AMP-kinase, which in turn inhibits mammalian target of rapamycin (mTOR). Non-AMPK dependent protective pathways may include reduction of insulin, insulin-like growth factor-1, leptin, inflammatory pathways and potentiation of adiponectin, all of which may have a role in tumourigenesis. A role in inhibiting cancer stem cells is also postulated. A number of large scale observational and cohort studies suggest metformin is associated with a reduced risk of a number of cancers, although the data is not conclusive. Recent randomised studies reporting use of metformin in treatment of cancer have revealed mixed results, and the results of much larger randomised trials of metformin as an adjuvant therapy in breast and colorectal cancers are awaited.

Metformin attenuates motility, contraction, and fibrogenic response of hepatic stellate cells in vivo and in vitro by activating AMP-activated protein kinase

AIM

To investigate the effect of metformin on activated hepatic stellate cells (HSCs) and the possible signaling pathways involved.

METHODS

A fibrotic mouse model was generated by intraperitoneal injection of carbon tetrachloride (CCl₄) and subsequent treatment with or without metformin. The level of fibrosis was detected by hematoxylin-eosin staining, Sirius Red staining, and immunohistochemistry. The HSC cell line LX-2 was used for in vitro studies. The effect of metformin on cell proliferation (CCK8 assay), motility (scratch test and Transwell assay), contraction (collagen gel contraction assay), extracellular matrix (ECM) secretion (Western blot), and angiogenesis (ELISA and tube formation assay) was investigated. We also analyzed the possible signaling pathways involved by Western blot analysis.

RESULTS

Mice developed marked liver fibrosis after intraperitoneal injection with CCl₄ for 6 wk. Metformin decreased the activation of HSCs, reduced the deposition of ECM, and inhibited angiogenesis in CCl₄-treated mice. Platelet-derived growth factor (PDGF) promoted the fibrogenic response of HSCs in vitro, while metformin inhibited the activation, proliferation, migration, and contraction of HSCs, and reduced the secretion of ECM. Metformin decreased the expression of vascular endothelial growth factor (VEGF) in HSCs through inhibition of hypoxia inducible factor (HIF)-1α in both PDGF-BB treatment and hypoxic conditions, and it down-regulated VEGF secretion by HSCs and inhibited HSC-based angiogenesis in hypoxic conditions in vitro. The inhibitory effects of metformin on activated HSCs were mediated by inhibiting the Akt/mammalian target of rapamycin (mTOR) and extracellular signal-regulated kinase (ERK) pathways via the activation of adenosine monophosphate-activated protein kinase (AMPK).

CONCLUSION

Metformin attenuates the fibrogenic response of HSCs in vivo and in vitro, and may therefore be useful for the treatment of chronic liver diseases.

Molecular targets of dietary phytochemicals for possible prevention and therapy of uterine fibroids: Focus on fibrosis

Uterine fibroids (myomas or leiomyomas) are common benign tumors of reproductive aged women. Fibroids are clinically apparent in 20-50% of women, and cause abnormal uterine bleeding, abdominal pain and discomfort, pregnancy complications and infertility. Unfortunately, limited numbers of medical treatment are available but no effective preventive strategies exist. Moreover, the benefits of medical treatments are tempered by lack of efficacy or serious adverse side effects. Fibrosis has recently been recognized as a key pathological event in leiomyoma development and growth. It is defined by the excessive deposition of extracellular matrix (ECM). ECM plays important role in making bulk structure of leiomyoma, and ECM-rich rigid structure is believed to be a cause of abnormal bleeding and pelvic pain/pressure. Dietary phytochemicals are known to regulate fibrotic process in different biological systems, and being considered as potential tool to manage human health. At present, very few dietary phytochemicals have been studied in uterine leiomyoma, and they are mostly known for their antiproliferative effects. Therefore, in this review, our aim was to introduce some dietary phytochemicals that could target fibrotic processes in leiomyoma. Thus, this review could serve as useful resource to develop antifibrotic drugs for possible prevention and treatment of uterine fibroids.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Blocking epithelial-to-mesenchymal transition in glioblastoma with a sextet of repurposed drugs: the EIS regimen

This paper outlines a treatment protocol to run alongside of standard current treatment of glioblastoma- resection, temozolomide and radiation. The epithelial to mesenchymal transition (EMT) inhibiting sextet, EIS Regimen, uses the ancillary attributes of six older medicines to impede EMT during glioblastoma. EMT is an actively motile, therapy-resisting, low proliferation, transient state that is an integral feature of cancers’ lethality generally and of glioblastoma specifically. It is believed to be during the EMT state that glioblastoma’s centrifugal migration occurs. EMT is also a feature of untreated glioblastoma but is enhanced by chemotherapy, by radiation and by surgical trauma. EIS Regimen uses the antifungal drug itraconazole to block Hedgehog signaling, the antidiabetes drug metformin to block AMP kinase (AMPK), the analgesic drug naproxen to block Rac1, the anti-fibrosis drug pirfenidone to block transforming growth factor-beta (TGF-beta), the psychiatric drug quetiapine to block receptor activator NFkB ligand (RANKL) and the antibiotic rifampin to block Wnt- all by their previously established ancillary attributes. All these systems have been identified as triggers of EMT and worthy targets to inhibit. The EIS Regimen drugs have a good safety profile when used individually. They are not expected to have any new side effects when combined. Further studies of the EIS Regimen are needed.

Suppression of hypoxia-induced excessive angiogenesis by metformin via elevating tumor blood perfusion

The anti-diabetic metformin has been demonstrated to be effective in suppression of tumor progression via multiple mechanisms, in which angiogenic inhibition is involved. Hypoxia is a common feather of malignant tumor and promotes angiogenesis via induction of pro-angiogenic factors. However, the effect of metformin on tumor hypoxia and the association with angiogenic inhibition are still unclear. In the current study, we investigated the effects of metformin on both tumor blood perfusion and hypoxia-induced excessive angiogenesis. In the tumor region adjacent to necrosis, aberrantly excessive angiogenesis resulted from hypoperfusion-induced intense hypoxia and greatly contributed to the high average levels of both microvessel density and vascular branch density. Metformin administration increased the percentage of lectin-perfused vessels and reduced hypoxyprobe-positive area. This metformin-induced amelioration of hypoxia was accompanied by a significant reduction in expressions of both HIF-1α and angiogenesis-associated factors (AAFs). Consequently, inhibited excessive angiogenesis in hypoxic peri-necrotic region was observed in metformin-treated tumor. Further stable knockdown of HIF-1α abrogated hypoxia-induced AAFs in vitro and reduced both microvessel density and area of fitc-conjugated dextran that leaked outside the vascular lumen. Taken together, metformin ameliorated tumor hypoxia and restrained HIF-1α-induced expressions of AAFs through elevating tumor blood perfusion, thus suppressing the excessive tumor angiogenesis.

A case of liver hemangioma with markedly reduced tumor size after metformin treatment: a case report

A 52-year-old man with a 9-year history of hepatic hemangioma was treated with the anti-diabetic drug metformin, resulting in complete remission of the tumor. In 2006, a hemangioma with diameter of 20 × 25 mm was detected incidentally in the liver. The results of imaging studies including ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI) were all compatible with that of hepatic hemangioma. The patient consequently underwent imaging annually from 2006 to 2015. The tumor size increased slightly, to 30 × 35 mm in 2012; however, the general tumor characteristics in imaging were not changed. Beginning May 2012, metformin (750 mg/day) was administered because of an increase in blood sugar and hemoglobin A1c levels. After the start of metformin treatment, the tumor size on US gradually decreased. Finally, in October 2015, the tumor was no longer detected. Dynamic CT study also demonstrated markedly reduced tumor size, with a decrease of 2-3 mm in diameter. These results indicate that metformin treatment strongly suppressed cell proliferation in liver hemangioma. The anti-angiogenic effect of metformin was indicated as a possible cause of the reduction in tumor size.

Metformin modulates apoptosis and cell signaling of human podocytes under high glucose conditions

Diabetic nephropathy, which is associated with loss of human (h) podocytes (PC), is a major complication in diabetes mellitus. High-glucose modulates AMP-activated protein kinase (AMPK) signaling and cell apoptosis. Metformin has been demonstrated to reduce apoptosis and albuminuria in type 2 diabetes. Here, we examined the effect of metformin on cell apoptosis and on pro-/anti-apoptotic signaling in hPC. Expression analyses were done by real-time polymerase chain reaction and western blotting. Moreover, a functional apoptosis assay was performed in hPC. Determination of kinase activation by phosphorylation was done via immunodetection analyses and digital quantification. We found that hPC express organic cation transporter 1 which is the major uptake transporter of metformin. High-glucose reduced AMPK phosphorylation and induced mammalian target of rapamycin (mTOR) activation in podocytes, which was abolished and reversed by pre-treatment with metformin. Furthermore, metformin reduced high-glucose-induced podocytes apoptosis in a concentration-dependent manner. In summary, metformin exhibits an anti-apoptotic impact on podocytes under high-glucose conditions via activation of AMPK and inhibition of mTOR signaling. These data support a beneficial effect of metformin in diabetic nephropathy.