Screening Novel Molecular Targets of Metformin in Breast Cancer by Proteomic Approach

Metformin restrains ZIKV replication and alleviates virus-induced inflammatory responses in microglia

The re-emergence of Zika virus (ZIKV) remains a major public health threat that has raised worldwide attention. Accumulating evidence suggests that ZIKV can cause serious pathological changes to the human nervous system, including microcephaly in newborns. Recent studies suggest that metformin, an established treatment for diabetes may play a role in viral infection; however, little is known about the interactions between ZIKV infection and metformin administration. Using fluorescent ZIKV by flow cytometry and immunofluorescence imaging, we found that ZIKV can infect microglia in a dose-dependent manner. Metformin diminished ZIKV replication without the alteration of viral entry and phagocytosis. Our study demonstrated that metformin downregulated ZIKV-induced inflammatory response in microglia in a time- and dose-dependent manner. Our RNA-Seq and qRT-PCR analysis found that type I and III interferons (IFN), such as IFNα2, IFNβ1 and IFNλ3 were upregulated in ZIKV-infected cells by metformin treatment, accompanied with the downregulation of GBP4, OAS1, MX1 and ISG15. Together, our results suggest that metformin-mediated modulation in multiple pathways may attribute to restraining ZIKV infection in microglia, which may provide a potential tool to consider for use in unique clinical circumstances.

Characterization of protein cargo of Echinococcus granulosus extracellular vesicles in drug response and its influence on immune response

BACKGROUND

The Echinococcus granulosus sensu lato species complex causes cystic echinococcosis, a zoonotic disease of medical importance. Parasite-derived small extracellular vesicles (sEVs) are involved in the interaction with hosts intervening in signal transduction related to parasite proliferation and disease pathogenesis. Although the characteristics of sEVs from E. granulosus protoscoleces and their interaction with host dendritic cells (DCs) have been described, the effect of sEVs recovered during parasite pharmacological treatment on the immune response remains unexplored.

METHODS

Here, we isolated and characterized sEVs from control and drug-treated protoscoleces by ultracentrifugation, transmission electron microscopy, dynamic light scattering, and proteomic analysis. In addition, we evaluated the cytokine response profile induced in murine bone marrow-derived dendritic cells (BMDCs) by qPCR.

RESULTS

The isolated sEVs, with conventional size between 50 and 200 nm, regardless of drug treatment, showed more than 500 cargo proteins and, importantly, 20 known antigens and 70 potential antigenic proteins, and several integral-transmembrane and soluble proteins mainly associated with signal transduction, immunomodulation, scaffolding factors, extracellular matrix-anchoring, and lipid transport. The identity and abundance of proteins in the sEV-cargo from metformin- and albendazole sulfoxide (ABZSO)-treated parasites were determined by proteomic analysis, detecting 107 and eight exclusive proteins, respectively, which include proteins related to the mechanisms of drug action. We also determined that the interaction of murine BMDCs with sEVs derived from control parasites and those treated with ABZSO and metformin increased the expression of pro-inflammatory cytokines such as IL-12 compared to control cells. Additionally, protoscolex-derived vesicles from metformin treatments induced the production of IL-6, TNF-α, and IL-10. However, the expression of IL-23 and TGF-β was downregulated.

CONCLUSIONS

We demonstrated that sEV-cargo derived from drug-treated E. granulosus protoscoleces have immunomodulatory functions, as they enhance DC activation towards a type 1 pro-inflammatory profile against the parasite, and therefore support the proposal of a new approach for the prevention and treatment of secondary echinococcosis.

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.

Sera from women with different metabolic and menopause states differentially regulate cell viability and Akt activation in a breast cancer in-vitro model

Obesity is associated with an increased incidence and aggressiveness of breast cancer and is estimated to increment the development of this tumor by 50 to 86%. These associations are driven, in part, by changes in the serum molecules. Epidemiological studies have reported that Metformin reduces the incidence of obesity-associated cancer, probably by regulating the metabolic state. In this study, we evaluated in a breast cancer in-vitro model the activation of the IR-β/Akt/p70S6K pathway by exposure to human sera with different metabolic and hormonal characteristics. Furthermore, we evaluated the effect of brief Metformin treatment on sera of obese postmenopausal women and its impact on Akt and NF-κB activation. We demonstrated that MCF-7 cells represent a robust cellular model to differentiate Akt pathway activation influenced by the stimulation with sera from obese women, resulting in increased cell viability rates compared to cells stimulated with sera from normal-weight women. In particular, stimulation with sera from postmenopausal obese women showed an increase in the phosphorylation of IR-β and Akt proteins. These effects were reversed after exposure of MCF-7 cells to sera from postmenopausal obese women with insulin resistance with Metformin treatment. Whereas sera from women without insulin resistance affected NF-κB regulation. We further demonstrated that sera from post-Metformin obese women induced an increase in p38 phosphorylation, independent of insulin resistance. Our results suggest a possible mechanism in which obesity-mediated serum molecules could enhance the development of luminal A-breast cancer by increasing Akt activation. Further, we provided evidence that the phenomenon was reversed by Metformin treatment in a subgroup of women.

Adverse Effects of Metformin From Diabetes to COVID-19, Cancer, Neurodegenerative Diseases, and Aging: Is VDAC1 a Common Target?

Metformin has been used for treating diabetes mellitus since the late 1950s. In addition to its antihyperglycemic activity, it was shown to be a potential drug candidate for treating a range of other diseases that include various cancers, cardiovascular diseases, diabetic kidney disease, neurodegenerative diseases, renal diseases, obesity, inflammation, COVID-19 in diabetic patients, and aging. In this review, we focus on the important aspects of mitochondrial dysfunction in energy metabolism and cell death with their gatekeeper VDAC1 (voltage-dependent anion channel 1) as a possible metformin target, and summarize metformin's effects in several diseases and gut microbiota. We question how the same drug can act on diseases with opposite characteristics, such as increasing apoptotic cell death in cancer, while inhibiting it in neurodegenerative diseases. Interestingly, metformin's adverse effects in many diseases all show VDAC1 involvement, suggesting that it is a common factor in metformin-affecting diseases. The findings that metformin has an opposite effect on various diseases are consistent with the fact that VDAC1 controls cell life and death, supporting the idea that it is a target for metformin.

Metformin and primary bone cancer risk in Taiwanese patients with type 2 diabetes mellitus

BACKGROUND

The effect of metformin on primary bone cancer risk has not been researched. This retrospective cohort study investigated the risk of primary bone cancer between metformin initiators and non-metformin initiators in patients with type 2 diabetes mellitus.

METHODS

A total of 673,532 patients with newly diagnosed type 2 diabetes mellitus and had been prescribed antidiabetic drugs for 2 or more times during 1999-2009 were enrolled from Taiwan's National Health Insurance. Metformin initiators and non-metformin initiators were defined according to the prescriptions of antidiabetic drugs within the initial 12 months. The patients were then followed up until December 31, 2011 for the incidence of primary bone cancer. Cox regression incorporated with the inverse probability of treatment-weighting using propensity scores was used to estimate hazard ratios in intention-to-treat and per-protocol analyses.

RESULTS

In the intention-to-treat analysis, the respective incidence rates were 10.56 and 12.90 per 100,000 person-years in 453,532 metformin initiators and 220,000 non-metformin initiators and the hazard ratio for initiators versus non-initiators was 0.830 (95% confidence interval 0.686-1.004, P-value = 0.0551). In the per-protocol analysis, the incidence rates were 7.58 and 11.77 per 100,000 person-years, respectively, and the hazard ratio was 0.615 (95% confidence interval 0.468-0.808, P-value = 0.0005). Subgroup analyses with regards to sex and age (<60 and ≥60 years) showed that the significantly lower risk associated with metformin use was only observed in men aged ≥60 years in the per-protocol analysis.

CONCLUSIONS

A significantly lower risk of primary bone cancer can be observed in patients with type 2 diabetes mellitus who adhere to metformin treatment. This benefit can only be observed in men aged ≥60 years.

Biguanides: Species with versatile therapeutic applications

Biguanides are compounds in which two guanidine moieties are fused to form a highly conjugated system. Biguanides are highly basic and hence they are available as salts mostly hydrochloride salts, these cationic species have been found to exhibit many therapeutic properties. This review covers the research and development carried out on biguanides and accounts the various therapeutic applications of drugs containing biguanide group-such as antimalarial, antidiabetic, antiviral, anticancer, antibacterial, antifungal, anti-tubercular, antifilarial, anti-HIV, as well as other biological activities. The aim of this review is to compile all the medicinal chemistry applications of this class of compounds so as to pave way for the accelerated efforts in finding the drug action mechanisms associated with this class of compounds. Importance has been given to the organic chemistry of these biguanide derivatives also.

Still Living Better through Chemistry: An Update on Caloric Restriction and Caloric Restriction Mimetics as Tools to Promote Health and Lifespan

Caloric restriction (CR), the reduction of caloric intake without inducing malnutrition, is the most reproducible method of extending health and lifespan across numerous organisms, including humans. However, with nearly one-third of the world’s population overweight, it is obvious that caloric restriction approaches are difficult for individuals to achieve. Therefore, identifying compounds that mimic CR is desirable to promote longer, healthier lifespans without the rigors of restricting diet. Many compounds, such as rapamycin (and its derivatives), metformin, or other naturally occurring products in our diets (nutraceuticals), induce CR-like states in laboratory models. An alternative to CR is the removal of specific elements (such as individual amino acids) from the diet. Despite our increasing knowledge of the multitude of CR approaches and CR mimetics, the extent to which these strategies overlap mechanistically remains unclear. Here we provide an update of CR and CR mimetic research, summarizing mechanisms by which these strategies influence genome function required to treat age-related pathologies and identify the molecular fountain of youth.

Metformin partially reverses the inhibitory effect of co-culture with ER-/PR-/HER2+ breast cancer cells on biomarkers of monocyte antitumor activity

BACKGROUND

Immune activities of monocytes (MOs) can be altered within the microenvironment of solid malignancies, including breast cancer. Metformin (1,1-dimethylbiguanide hydrochloride, MET), has been shown to decrease tumor cell proliferation, but its effects have yet to be explored with respect to MOs (monocytes) activity during their crosstalk with breast cancer cells. Here, we investigated the effects of MET on overall phenotypic functional activities, including cellular immunometabolism and protective redox signaling based-biomarkers, intracellular free calcium ions (ifCa2+), phagocytosis and co-operative cytokines (IFN-γ and IL-10) of autologous MOs before and during their interplay with primary ER-/PR-/HER2+ breast cancer cells.

METHODS

Human primary breast cancer cells were either cultured alone or co-cultured with autologous MOs before treatment with MET.

RESULTS

MET downregulated breast cancer cell proliferation and phagocytosis, while having no significant effect on the ratio of phosphorylated Akt (p-Akt) to total Akt. Additionally, we observed that, in the absence of MET treatment, the levels of lactate dehydrogenase (LDH)-based cytotoxicity, catalase, ifCa2+, IL-10 and arginase activity were significantly reduced in co-cultures compared to levels in MOs cultured alone whereas levels of inducible nitric oxide synthase (iNOS) activity were significantly increased. In contrast, MET treatment reduced the effects measured in co-culture on the levels of LDH-based cytotoxicity, arginase activity, catalase, ifCa2+, and IFN-γ. MET also induced upregulation of both iNOS and arginase in MO cells, although the increase did not reach significant difference for iNOS activity. Moreover, MET induced a robust increase of superoxide dismutase (SOD) activity in MOs, but not in MOs co-cultured with breast cancer cells. Furthermore, MET markedly upregulated the levels of IFN-γ production and downregulated those of IL-10 in isolated MOs, while inducing a slight opposing up-regulation of IL-10 production in co-cultures.

CONCLUSIONS

Our results show that the biomarkers of phenotypic functional activities of MOs are modified after co-culturing with primary human breast cancer cells. Treatment of co-cultures with MET resulted in increased release of antitumor cytokine IFN-γ and ifCa2+, and increased cell necrosis during breast cancer cells-MOs crosstalk.

Combination of Curcumin and Metformin Inhibits Cell Growth and Induces Apoptosis without Affecting the Cell Cycle in LNCaP Prostate Cancer Cell Line

Side effects and chemotherapy resistance, demand new therapeutics with minimal side effects. Here, we investigated the combined effect of curcumin and metformin on the LNCaP prostate cancer cell line. LNCaP cells were treated with curcumin, metformin, and their combination at different concentrations. Cell viability was assessed by MTT assay and expression of Bax, Bcl-2, mTOR, hTERT, PUMA, p53 and p21 genes was analyzed by real-time PCR. Apoptosis and cell cycle were assessed by flow cytometry. Our results revealed that the viability of cells treated with curcumin, metformin, and their combination was significantly (P < 0.05) reduced with increasing the concentration and prolonging the treatment time. Meanwhile, the combination showed a synergistic effect within 48 h. In the curcumin treated group, the expression of Bcl-2 and hTERT genes diminished. In the metformin treated group, the expression of Bax and PUMA genes was enhanced while the expression of Bcl-2, hTERT, mTOR, and p53 genes declined. Although all treatments induced apoptosis, the combination of curcumin and metformin showed the maximum level of apoptosis, cytotoxicity, and expression of Bax gene. The combination of curcumin and metformin showed synergistic effects within 48 h. This combination could be a potential therapeutic candidate for prostate cancer to be further investigated.

Derlin-1 functions as a growth promoter in breast cancer

Breast cancer is one of the most common malignant tumors in women. Derlin-1 has been found to be overexpressed in several human cancers in addition to playing an important role in tumor processes; however, the expression patterns and functions of Derlin-1 in human breast cancer are not fully understood. In this study, we found that Derlin-1 overexpression was higher in breast cancer compared to normal samples through TCGA and GTEx database analyses. Kaplan-Meier plotter analysis showed that Derlin-1 was a predicting factor for patient prognosis. Derlin-1 expression was significantly up-regulated in breast cancer tissues (18/30, 60.00%) compared to corresponding paracancerous tissue (9/30, 30.00%, p < 0.05) as detected by immunohistochemistry, and the expression of Derlin-1 was correlated to pathological grading. siRNA interference of Derlin-1 inhibited cell proliferation, which is associated with the promotion of apoptosis and migration. Derlin-1 knockdown suppressed the protein levels of p-AKT and Cyclin D1 while up-regulating Caspase3 and Bax. GEPIA database analysis showed that MTDH and ATAD2 were downstream target genes, and the expression of MTDH and was suppressed in Derlin-1 knockdown cells. Taken together, our results demonstrated ATAD2 that Derlin-1 is overexpressed in breast cancer and promoted a malignant phenotype through the AKT signaling pathway.

Metformin overcomes resistance to cisplatin in triple-negative breast cancer (TNBC) cells by targeting RAD51

BACKGROUND

Chemotherapy is a standard therapeutic regimen to treat triple-negative breast cancer (TNBC); however, chemotherapy alone does not result in significant improvement and often leads to drug resistance in patients. In contrast, combination therapy has proven to be an effective strategy for TNBC treatment. Whether metformin enhances the anticancer effects of cisplatin and prevents cisplatin resistance in TNBC cells has not been reported.

METHODS

Cell viability, wounding healing, and invasion assays were performed on Hs 578T and MDA-MB-231 human TNBC cell lines to demonstrate the anticancer effects of combined cisplatin and metformin treatment compared to treatment with cisplatin alone. Western blotting and immunofluorescence were used to determine the expression of RAD51 and gamma-H2AX. In an in vivo 4T1 murine breast cancer model, a synergistic anticancer effect of metformin and cisplatin was observed.

RESULTS

Cisplatin combined with metformin decreased cell viability and metastatic effect more than cisplatin alone. Metformin suppressed cisplatin-mediated RAD51 upregulation by decreasing RAD51 protein stability and increasing its ubiquitination. In contrast, cisplatin increased RAD51 expression in an ERK-dependent manner. In addition, metformin also increased cisplatin-induced phosphorylation of γ-H2AX. Overexpression of RAD51 blocked the metformin-induced inhibition of cell migration and invasion, while RAD51 knockdown enhanced cisplatin activity. Moreover, the combination of metformin and cisplatin exhibited a synergistic anticancer effect in an orthotopic murine model of 4T1 breast cancer in vivo.

CONCLUSIONS

Metformin enhances anticancer effect of cisplatin by downregulating RAD51 expression, which represents a novel therapeutic target in TNBC management.

Personalized medicine in breast cancer: pharmacogenomics approaches

Abstract: Breast cancer is the fifth cause of cancer death among women worldwide and represents a global health concern due to the lack of effective therapeutic regimens that could be applied to all disease groups. Nowadays, strategies based on pharmacogenomics constitute novel approaches that minimize toxicity while maximizing drug efficacy; this being of high importance in the oncology setting. Besides, genetic profiling of malignant tumors can lead to the development of targeted therapies to be included in effective drug regimens. Advances in molecular diagnostics have revealed that breast cancer is a multifaceted disease, characterized by inter-tumoral and intra-tumoral heterogeneity and, unlike the past, molecular classifications based on the expression of individual biomarkers have led to devising novel therapeutic strategies that improve patient survival. In this review, we report and discuss the molecular classification of breast cancer subtypes, the heterogeneity resource, and the advantages and disadvantages of current drug regimens with consideration of pharmacogenomics in response and resistance to treatment.

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-induced apoptosis facilitates degradation of the cellular caspase 8 (FLICE)-like inhibitory protein through a caspase-dependent pathway in human renal cell carcinoma A498 cells

Renal cell carcinoma (RCC) is one of the most common types of cancer in adults. Previous studies have reported that the survival rate was significantly lower for renal cancer patients with diabetes than for those without diabetes. Metformin is a well-known anti-diabetic agent used for the treatment of type 2 diabetes mellitus (T2DM). It also inhibits cell proliferation and angiogenesis and is known to possess antitumor effects. However, the molecular mechanism for metformin-induced apoptosis in renal cell carcinoma is not understood. In the present study, treatment with metformin induced apoptosis in A498 cells in a dose-dependent manner. It was revealed that degradation of cellular caspase 8 (FLICE)-like inhibitory protein (c-FLIP) and activation of procaspase-8 were associated with metformin-mediated apoptosis. By contrast, treatment with metformin did not affect the mRNA level of c-FLIP_L in A498 cells. Treatment with benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (z-VAD-fmk, a pan-caspase inhibitor) almost completely blocked metformin-induced apoptosis and degradation of c-FLIP_L protein. However, N-acetyl-L-cysteine (NAC), a reactive oxygen species (ROS) scavenger, did not inhibit metformin-mediated apoptosis in A498 cells. Taken together, the results of the present study demonstrated that metformin-induced apoptosis involved degradation of the c-FLIP_L protein and activation of caspase-8 in human renal cell carcinoma A498 cells and suggested that metformin could be potentially used for the treatment of renal cancer.