Metformin inhibits human breast cancer cell growth by promoting apoptosis via a ROS-independent pathway involving mitochondrial dysfunction: pivotal role of superoxide dismutase (SOD)

Metformin represses the carcinogenesis potentially induced by 50 Hz magnetic fields in aged mouse fibroblasts via inhibition of NF-kB

Aging is a risk factor for various human disorders, including cancer. Current literature advocates that the primary principles of aging depend on the endogenous stress-induced DNA damage caused by reactive oxygen species 50 Hz low-frequency magnetic field was suggested to induce DNA damage and chromosomal instability. NF-kB, activated by DNA damage, is upregulated in age-related cancers and inhibition of NF-kB results in aging-related delayed pathologies. Metformin (Met), an NF-kB inhibitor, significantly reduces both NF-kB activation and expression in aging and cancer. This in vitro study, therefore, was set out to assess the effects of 5mT MF in 50 Hz frequency and Met treatment on the viability and proliferation of aged mouse NIH/3T3 fibroblasts and expression of RELA/p65, matrix metalloproteinases MMP2 and MMP9, and E-cadherin (CDH1) genes. The trypan blue exclusion assay was used to determine cell viability and the BrdU incorporation assay to determine cell proliferation. The MMP-2/9 protein analysis was carried out by immunocytochemistry, NF-kB activity by ELISA and the expressions of targeted genes by qRT-PCR methods. Four doses of Met (500 uM, 1 mM, 2 mM and 10 mM) suppressed both the proliferation and viability of fibroblasts exposed to the MF in a dose-dependent pattern, and the peak inhibition was recorded at the 10 mM dose. Met reduced the expression of NF-kB, and MMP2/9, elevated CDH1 expression and suppressed NF-kB activity. These findings suggest that Met treatment suppresses the carcinogenic potential of 50 Hz MFs in aged mouse fibroblasts, possibly through modulation of NF-kB activation and epithelial-mesenchymal transition modulation.

Therapeutic Potential of Terpenoids in Cancer Treatment: Targeting Mitochondrial Pathways

BACKGROUND

In recent decades, natural compounds have been considered a significant source of new antitumor medicines due to their unique advantages. Several in vitro and in vivo studies have focused on the effect of terpenoids on apoptosis mediated by mitochondria in malignant cells.

RECENT FINDINGS

In this review article, we focused on six extensively studied terpenoids, including sesquiterpenes (dihydroartemisinin and parthenolide), diterpenes (oridonin and triptolide), and triterpenes (betulinic acid and oleanolic acid), and their efficacy in targeting mitochondria to induce cell death. Terpenoid-induced mitochondria-related cell death includes apoptosis, pyroptosis, necroptosis, ferroptosis, autophagy, and necrosis caused by mitochondrial permeability transition. Apoptosis and autophagy interact in meaningful ways. In addition, in view of several disadvantages of terpenoids, such as low stability and bioavailability, advances in research on combination chemotherapy and chemical modification were surveyed.

CONCLUSION

This article deepens our understanding of the association between terpenoids and mitochondrial cell death, presenting a hypothetical basis for the use of terpenoids in anticancer management.

Role of MicroRNA in linking diabetic retinal neurodegeneration and vascular degeneration

Diabetic retinopathy is the major cause of blindness in diabetic patients, with limited treatment options that do not always restore optimal vision. Retinal nerve degeneration and vascular degeneration are two primary pathological processes of diabetic retinopathy. The retinal nervous system and vascular cells have a close coupling relationship. The connection between neurodegeneration and vascular degeneration is not yet fully understood. Recent studies have found that microRNA plays a role in regulating diabetic retinal neurovascular degeneration and can help delay the progression of the disease. This article will review how microRNA acts as a bridge connecting diabetic retinal neurodegeneration and vascular degeneration, focusing on the mechanisms of apoptosis, oxidative stress, inflammation, and endothelial factors. The aim is to identify valuable targets for new research and clinical treatment of diabetic retinopathy.

Research progress on the role of reactive oxygen species in the initiation, development and treatment of breast cancer

According to international cancer data, breast cancer (BC) is the leading type of cancer in women. Although significant progress has been made in treating BC, metastasis and drug resistance continue to be the primary causes of mortality for many patients. Reactive oxygen species (ROS) play a dual role in vivo: normal levels can maintain the body's normal physiological function; however, high levels of ROS below the toxicity threshold can lead to mtDNA damage, activation of proto-oncogenes, and inhibition of tumor suppressor genes, which are important causes of BC. Differences in the production and regulation of ROS in different BC subtypes have important implications for the development and treatment of BC. ROS can also serve as an important intracellular signal transduction factor by affecting the antioxidant system, activating MAPK and PI3K/AKT, and other signal pathways to regulate cell cycle and change the relationship between cells and the activity of metalloproteinases, which significantly impacts the metastasis of BC. Hypoxia in the BC microenvironment increases ROS production levels, thereby inducing the expression of hypoxia inducible factor-1α (HIF-1α) and forming "ROS- HIF-1α-ROS" cycle that exacerbates BC development. Many anti-BC therapies generate sufficient toxic ROS to promote cancer cell apoptosis, but because the basal level of ROS in BC cells exceeds that of normal cells, this leads to up-regulation of the antioxidant system, drug efflux, and apoptosis inhibition, rendering BC cells resistant to the drug. ROS crosstalks with tumor vessels and stromal cells in the microenvironment, increasing invasiveness and drug resistance in BC.

Metformin: From Diabetes to Cancer-Unveiling Molecular Mechanisms and Therapeutic Strategies

Metformin, a widely used anti-diabetic drug, has garnered attention for its potential in cancer management, particularly in breast and colorectal cancer. It is established that metformin reduces mitochondrial respiration, but its specific molecular targets within mitochondria vary. Proposed mechanisms include inhibiting mitochondrial respiratory chain Complex I and/or Complex IV, and mitochondrial glycerophosphate dehydrogenase, among others. These actions lead to cellular energy deficits, redox state changes, and several molecular changes that reduce hyperglycemia in type 2 diabetic patients. Clinical evidence supports metformin's role in cancer prevention in type 2 diabetes mellitus patients. Moreover, in these patients with breast and colorectal cancer, metformin consumption leads to an improvement in survival outcomes and prognosis. The synergistic effects of metformin with chemotherapy and immunotherapy highlights its potential as an adjunctive therapy for breast and colorectal cancer. However, nuanced findings underscore the need for further research and stratification by molecular subtype, particularly for breast cancer. This comprehensive review integrates metformin-related findings from epidemiological, clinical, and preclinical studies in breast and colorectal cancer. Here, we discuss current research addressed to define metformin's bioavailability and efficacy, exploring novel metformin-based compounds and drug delivery systems, including derivatives targeting mitochondria, combination therapies, and novel nanoformulations, showing enhanced anticancer effects.

Differential Effect of 4H-Benzo[d] [1, 3]oxazines on the Proliferation of Breast Cancer Cell Lines

BACKGROUND

A family of 4H-benzo[d][1,3]oxazines were obtained from a group of N-(2-alkynyl)aryl benzamides precursors via gold(I) catalysed chemoselective 6-exo-dig C-O cyclization.

METHOD

The precursors and oxazines obtained were studied in breast cancer cell lines MCF-7, CAMA-1, HCC1954 and SKBR-3 with differential biological activity showing various degrees of inhibition with a notable effect for those that had an aryl substituted at C-2 of the molecules. 4H-benzo[d][1,3]oxazines showed an IC50 rating from 0.30 to 157.4 µM in MCF-7, 0.16 to 139 in CAMA-1, 0.09 to 93.08 in SKBR-3, and 0.51 to 157.2 in HCC1954 cells.

RESULTS

We observed that etoposide is similar to benzoxazines while taxol effect is more potent. Four cell lines responded to benzoxazines while SKBR-3 cell line responded to precursors and benzoxazines. Compounds 16, 24, 25 and 26 have the potent effect in cell proliferation inhibition in the 4 cell lines tested and correlated with oxidant activity suggesting a possible mechanism by ROS generation.

CONCLUSION

These compounds represent possible drug candidates for the treatment of breast cancer. However, further trials are needed to elucidate its full effect on cellular and molecular features of cancer.

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.

Mechanisms of Regulation of the Expression of miRNAs and lncRNAs by Metformin in Ovarian Cancer

Ovarian cancer (OC) is one of the most lethal gynecological malignancies. The use of biological compounds such as non-coding RNAs (ncRNAs) is being considered as a therapeutic option to improve or complement current treatments since the deregulation of ncRNAs has been implicated in the pathogenesis and progression of OC. Old drugs with antitumoral properties have also been studied in the context of cancer, although their antitumor mechanisms are not fully clear. For instance, the antidiabetic drug metformin has shown pleiotropic effects in several in vitro models of cancer, including OC. Interestingly, metformin has been reported to regulate ncRNAs, which could explain its diverse effects on tumor cells. In this review, we discuss the mechanism of epigenetic regulation described for metformin, with a focus on the evidence of metformin-dependent microRNA (miRNAs) and long non-coding RNA (lncRNAs) regulation in OC.

Cyclometalated ruthenium (II) complexes induced HeLa cell apoptosis through intracellular reductive injury

The main challenge of cancer chemotherapy is the resistance of tumor cells to oxidative damage. Herein, we proposed a novel antitumor strategy: cyclic metal‑ruthenium (Ru) complexes mediate reductive damage to kill tumor cells. We designed and synthesized Ru(II) complexes with β-carboline as ligands: [Ru (phen)2(NO2-Ph-βC)](PF6) (RuβC-7) and [Ru(phen)2(1-Ph-βC)](PF6) (RuβC-8). In vitro experimental results showed that RuβC-7 and RuβC-8 can inhibit cell proliferation, promote mitochondrial abnormalities, and induce DNA damage. Interestingly, RuβC-7 with SOD activity could reduce intracellular reactive oxygen species (ROS) levels, while RuβC-8 has the opposite effect. Accordingly, this study identified the reductive damage mechanism of tumor apoptosis, and may provide a new ideas for the design of novel metal complexes.

Oxidative brain and cerebellum injury in diabetes and prostate cancer model: Protective effect of metformin

The body can host the spread of prostate cancer cells. Metastases from prostate cancer are more frequently seen in the brain, liver, lungs, and lymph nodes. A well-known antidiabetic drug, metformin, is also known to have antitumor effects. Our study focuses on the evaluation of potential metformin protective effects on brain and cerebellum damage in streptozotocin (STZ)-induced diabetic and Dunning prostate cancer models. In this investigation, six groups of male Copenhagen rats were created: control, diabetic (D), cancer (C), diabetic + cancer (DC), cancer + metformin, and diabetic + cancer + metformin. The brain and cerebellum tissues of the rats were taken after sacrifice. Oxidative stress markers including reduced glutathione level, lipid peroxidation, glutathione reductase, glutathione peroxidase, glutathione-S-transferase, catalase, superoxide dismutase activities, reactive oxygen species, total oxidant and total antioxidant status, lactate dehydrogenase, xanthine oxidase, acetylcholinesterase activities, protein carbonyl contents, nitric oxide and OH-proline levels, sodium potassium ATPase, carbonic anhydrase, and glucose-6-phosphate dehydrogenase activities; glycoprotein levels including hexose, hexosamine, fucose, and sialic acid levels; and histone deacetylase activity as a cancer marker were determined. Oxidative stress markers were impaired and glycoprotein levels and histone deacetylase activity were increased in the D, C, and DC groups. Metformin therapy reversed these effects. Metformin was found to protect the brain and cerebellum of STZ-induced diabetic rats with Dunning prostate cancer from harm caused by MAT-Lylu metastatic cells.

Functional Materials for Subcellular Targeting Strategies in Cancer Therapy: Progress and Prospects

Neoadjuvant and adjuvant therapies have made significant progress in cancer treatment. However, tumor adjuvant therapy still faces challenges due to the intrinsic heterogeneity of cancer, genomic instability, and the formation of an immunosuppressive tumor microenvironment. Functional materials possess unique biological properties such as long circulation times, tumor-specific targeting, and immunomodulation. The combination of functional materials with natural substances and nanotechnology has led to the development of smart biomaterials with multiple functions, high biocompatibilities, and negligible immunogenicities, which can be used for precise cancer treatment. Recently, subcellular structure-targeting functional materials have received particular attention in various biomedical applications including the diagnosis, sensing, and imaging of tumors and drug delivery. Subcellular organelle-targeting materials can precisely accumulate therapeutic agents in organelles, considerably reduce the threshold dosages of therapeutic agents, and minimize drug-related side effects. This review provides a systematic and comprehensive overview of the research progress in subcellular organelle-targeted cancer therapy based on functional nanomaterials. Moreover, it explains the challenges and prospects of subcellular organelle-targeting functional materials in precision oncology. The review will serve as an excellent cutting-edge guide for researchers in the field of subcellular organelle-targeted cancer therapy.

Effect of metformin use on the risk and prognosis of ovarian cancer: an updated systematic review and meta-analysis

INTRODUCTION

Emerging evidence suggests that metformin has a potential antitumor effect both in vitro and in vivo. Increasing epidemiological studies indicate that diabetic patients receiving metformin therapy have lower incidences of cancer and have better survival rates. However, there are limited and inconsistent studies available about the effect of metformin therapy on ovarian cancer (OC). Thus, we conducted this meta-analysis to study the effect of metformin therapy on OC. Meanwhile, we systematically reviewed relevant studies to provide a framework for future research.

EVIDENCE ACQUISITION

We conducted a systematic literature search on PubMed, Web of Science, Springerlink, CNKI, VIP, SinoMed, and Wanfang up to the period of October 2018. A random-effects meta-analysis model was used to derive pooled effect estimates.

EVIDENCE SYNTHESIS

A total of 13 studies were retrieved of which 5 studies explained the prevention and 8 studies explained the treatment for OC. Our pooled results showed that metformin has a potential preventive effect on OC in diabetic women (pooled odds ratio [OR] 0.62, 95% confidence interval [95% CI] 0.34, 1.11; P<0.001). In addition, metformin can also significantly prolong progression-free survival (PFS) (pooled hazard ratio [HR] 0.49, 95% CI 0.34, 0.70; P=0.002), and overall survival (OS) (HR 0.71, 95%CI 0.61, 0.82; P<0.001) in patients with OC, regardless of whether they had diabetes.

CONCLUSIONS

The use of metformin can potentially reduce the risk of OC among diabetics, and it also can significantly improve PFS and OS in patients with OC. A further large clinical investigation would be needed to adopt our finding in practice, however, our systematic review provides an insight for future study designs.

Deciphering the role of MitomiRs in cancer: A comprehensive review

MicroRNAs (miRNAs) are short non-coding RNAs that regulate many metabolic and signal transduction pathways. The role of miRNAs, usually found in the cytoplasm, in regulating gene expression and cancer progression has been extensively studied in the last few decades. However, very recently, miRNAs were found to localize in the mitochondria. MiRNAs that specifically localize in the mitochondria and the cytoplasmic miRNAs associated with mitochondria that directly or indirectly modulate specific mitochondrial functions are termed as "mitomiRs". Although it is not clear about the origin of mitomiRs that are situated within mitochondria (nuclear or mitochondrial origin), it is evident that they have specific functions in modulating gene expression and regulating important mitochondrial metabolic pathways. Through this review, we aim to delineate the mechanisms by which mitomiRs alter mitochondrial metabolic pathways and influence the initiation and progression of cancer. We further discuss the functions of particular mitomiRs, which have been widely studied in the context of mitochondrial metabolism and oncogenic signaling pathways. Based on the current knowledge, we can conclude that mitomiRs contribute significantly to mitochondrial function and metabolic regulation, and that dysregulation of mitomiRs can aid the proliferation of cancer cells. Therefore, the less explored area of mitomiRs' biology can be an important topic of research investigation in the future for targeting cancer cells.

Identification of CYP3A4 inhibitors as potential anti-cancer agents using pharmacoinformatics approach

Biguanide derivatives exhibit a wide variety of therapeutic applications, including anti-cancer effects. Metformin is an effective anti-cancer agent against breast cancer, lung cancer, and prostate cancer. In the crystal structure (PDB ID: 5G5J), it was found that metformin is found in the active site of CYP3A4, and the associated anti-cancer effect was explored. Taking clues from this work, pharmacoinformatics research has been carried out on a series of known and virtual biguanide, guanylthiourea (GTU), and nitreone derivatives. This exercise led to the identification of more than 100 species that exhibit greater binding affinity toward CYP3A4 in comparison to that of metformin. Selected six molecules were subjected to molecular dynamics simulations, and the results are presented in this work.

Metformin enhances anti-cancer properties of resveratrol in MCF-7 breast cancer cells via induction of apoptosis, autophagy and alteration in cell cycle distribution

Breast cancer is the fifth leading cause of death, worldwide affecting both genders. Accumulating evidence suggests that metformin, an oral hypoglycemic agent used in the management of type 2 diabetes, exerts anti-tumor effects in many cancers, including the breast cancer. Resveratrol, a natural product found abundantly in many fruits, exhibits marked cytotoxic and pro-oxidant effects. This study was designed to investigate the effect of metformin in combination with resveratrol and cisplatin in MCF-7 cells. Study groups were as follows: untreated control group, single treatment groups (metformin, resveratrol, and cisplatin), double treatment groups (metformin + resveratrol, metformin + cisplatin, and cisplatin + resveratrol) and triple treatment groups (metformin + resveratrol + cisplatin). Our results indicated that metformin inhibits proliferation of MCF-7 cells, an effect that was associated with ROS production and G0/G1 cell cycle arrest, but not apoptosis. Moreover, resveratrol suppressed the proliferation of MCF-7 cells by induction of apoptosis as well as cell cycle arrest. Notably, a significant inhibitory effect in the co-treatment of metformin, resveratrol, and cisplatin was observed which was attributed to induction of autophagy-mediated cell death and apoptosis along cell cycle arrest. In conclusion, our results advocate the anti-cancer properties of metformin and resveratrol on MCF-7 cell s via induction of cell cycle arrest. Additionally, synergistic anti-cancer effects of metformin in a triple combination with cisplatin and resveratrol was attributed to induction of autophagy-mediated cell death and apoptosis along cell cycle arrest. Based on our findings it is proposed that patients may benefit from addition of a drug with a safe profile to conventional anticancer therapies.

Mito-TEMPO, a Mitochondria-Targeted Antioxidant, Improves Cognitive Dysfunction due to Hypoglycemia: an Association with Reduced Pericyte Loss and Blood-Brain Barrier Leakage

Hypoglycemia is associated with cognitive dysfunction, but the exact mechanisms have not been elucidated. Our previous study found that severe hypoglycemia could lead to cognitive dysfunction in a type 1 diabetes (T1D) mouse model. Thus, the aim of this study was to further investigate whether the mechanism of severe hypoglycemia leading to cognitive dysfunction is related to oxidative stress-mediated pericyte loss and blood-brain barrier (BBB) leakage. A streptozotocin T1D model (150 mg/kg, one-time intraperitoneal injection), using male C57BL/6J mice, was used to induce hypoglycemia. Brain tissue was extracted to examine for neuronal damage, permeability of BBB was investigated through Evans blue staining and electron microscopy, reactive oxygen species and adenosine triphosphate in brain tissue were assayed, and the functional changes of pericytes were determined. Cognitive function was tested using Morris water maze. Also, an in vitro glucose deprivation model was constructed. The results showed that BBB leakage after hypoglycemia is associated with excessive activation of oxidative stress and mitochondrial dysfunction due to glucose deprivation/reperfusion. Interventions using the mitochondria-targeted antioxidant Mito-TEMPO in both in vivo and in vitro models reduced mitochondrial oxidative stress, decreased pericyte loss and apoptosis, and attenuated BBB leakage and neuronal damage, ultimately leading to improved cognitive function.

Apigenin in cancer therapy: Prevention of genomic instability and anticancer mechanisms

The incidence of cancer has been growing worldwide. Better survival rates following the administration of novel drugs and new combination therapies may concomitantly cause concern regarding the long-term adverse effects of cancer therapy, for example, second primary malignancies. Moreover, overcoming tumour resistance to anticancer agents has been long considered as a critical challenge in cancer research. Some low toxic adjuvants such as herb-derived molecules may be of interest for chemoprevention and overcoming the resistance of malignancies to cancer therapy. Apigenin is a plant-derived molecule with attractive properties for chemoprevention, for instance, promising anti-tumour effects, which may make it a desirable adjuvant to reduce genomic instability and the risks of second malignancies among normal tissues. Moreover, it may improve the efficiency of anticancer modalities. This paper aims to review various effects of apigenin in both normal tissues and malignancies. In addition, we explain how apigenin may have the ability to protect usual cells against the genotoxic repercussions following radiotherapy and chemotherapy. Furthermore, the inhibitory effects of apigenin on tumours will be discussed.

Chronic exposure to realistic concentrations of metformin prompts a neurotoxic response in Danio rerio adults

Metformin (MET) is among the most consumed drugs around the world, and thus, it is considered the uppermost drug in mass discharged into water settings. Nonetheless, data about the deleterious consequences of MET on water organisms are still scarce and require further investigation. Herein, we aimed to establish whether or not chronic exposure to MET (1, 20, and 40 μg/L) may alter the swimming behavior and induce neurotoxicity in Danio rerio adults. After 4 months of exposure, MET-exposed fish exhibited less swimming activity when compared to control fish. Moreover, compared with the control group, MET significantly inhibited the activity of AChE and induced oxidative damage in the brain of fish. Concerning gene expression, MET significantly upregulated the expression of Nrf1, Nrf2, BAX, p53, BACE1, APP, PSEN1, and downregulated CASP3 and CASP9. Although MET did not overexpress the CASP3 gene, we saw a meaningful rise in the activity of this enzyme in the blood of fish exposed to MET compared to the control group, which we then confirmed by a high number of apoptotic cells in the TUNEL assay. Our findings demonstrate that chronic exposure to MET may impair fish swimming behavior, making them more vulnerable to predators.

Redox balance and autophagy regulation in cancer progression and their therapeutic perspective

Cellular ROS production participates in various cellular functions but its accumulation decides the cell fate. Malignant cells have higher levels of ROS and active antioxidant machinery, a characteristic hallmark of cancer with an outcome of activation of stress-induced pathways like autophagy. Autophagy is an intracellular catabolic process that produces alternative raw materials to meet the energy demand of cells and is influenced by the cellular redox state thus playing a definite role in cancer cell fate. Since damaged mitochondria are the main source of ROS in the cell, however, cancer cells remove them by upregulating the process of mitophagy which is known to play a decisive role in tumorigenesis and tumor progression. Chemotherapy exploits cell machinery which results in the accumulation of toxic levels of ROS in cells resulting in cell death by activating either of the pathways like apoptosis, necrosis, ferroptosis or autophagy in them. So understanding these redox and autophagy regulations offers a promising method to design and develop new cancer therapies that can be very effective and durable for years. This review will give a summary of the current therapeutic molecules targeting redox regulation and autophagy for the treatment of cancer. Further, it will highlight various challenges in developing anticancer agents due to autophagy and ROS regulation in the cell and insights into the development of future therapies.

Inhibition of Autophagy Promotes the Anti-Tumor Effect of Metformin in Oral Squamous Cell Carcinoma

Oral Squamous Cell Carcinoma (OSCC) is the most common malignant tumor in the head and neck. Due to its high malignancy and easy recurrence, the five-year survival rate is only 50–60%. Currently, commonly used chemotherapy drugs for OSCC include cisplatin, paclitaxel, and fluorouracil, which are highly cytotoxic and cause drug resistance in patients. Therefore, a safe and effective treatment strategy for OSCC is urgent. To address this issue, our study investigated the anti-tumor activity of metformin (the first-line diabetes drug) in OSCC. We found that metformin could inhibit OSCC cell proliferation by promoting apoptosis and blocking the cell cycle in G1 phase. Additionally, we also found that metformin could induce protective autophagy of OSCC cells. After inhibiting autophagy with hydroxychloroquine (HCQ), the metformin-induced apoptosis was enhanced. In vitro, metformin inhibited the growth of subcutaneous xenograft tumor in nude mice and HCQ enhanced this effect of metformin. Therefore, metformin combined with HCQ may become a safe and effective treatment strategy for OSCC.

Mitochondrial miRNAs (MitomiRs): Their potential roles in breast and other cancers

Breast cancer is the most common cancer in women worldwide. MicroRNAs (miRNAs) are non-coding RNAs that are involved in the post-transcriptional regulation of gene expression. Although miRNAs mainly act in the cytoplasm, they can be found in the mitochondrial compartment of the cell. These miRNAs called "MitomiR", they can change mitochondrial functions by regulating proteins at the mitochondrial level and cause cancer. In this review, we have aimed to explain miRNA biogenesis, transport pathways to mitochondria, and summarize mitomiRs that have been shown to play an important role in mitochondrial function, especially in the initiation and progression of breast cancer.

Exploring the Mechanism of Adjuvant Treatment of Glioblastoma Using Temozolomide and Metformin

Glioblastoma is the most frequent and lethal primary central nervous system tumor in adults, accounting for around 15% of intracranial neoplasms and 40–50% of all primary malignant brain tumors, with an annual incidence of 3–6 cases per 100,000 population. Despite maximum treatment, patients only have a median survival time of 15 months. Metformin is a biguanide drug utilized as the first-line medication in treating type 2 diabetes. Recently, researchers have noticed that metformin can contribute to antineoplastic activity. The objective of this study is to investigate the mechanism of metformin as a potential adjuvant treatment drug in glioblastoma. Glioblastoma cell lines U87MG, LNZ308, and LN229 were treated with metformin, and several cellular functions and metabolic states were evaluated. First, the proliferation capability was investigated using the MTS assay and BrdU assay, while cell apoptosis was evaluated using the annexin V assay. Next, a wound-healing assay and mesenchymal biomarkers (N-cadherin, vimentin, and Twist) were used to detect the cell migration ability and epithelial–mesenchymal transition (EMT) status of tumor cells. Gene set enrichment analysis (GSEA) was applied to the transcriptome of the metformin-treated glioblastoma cell line. Then, DCFH-DA and MitoSOX Red dyes were used to quantify reactive oxygen species (ROS) in the cytosol and mitochondria. JC-1 dye and Western blotting analysis were used to evaluate mitochondrial membrane potential and biogenesis. In addition, the combinatory effect of temozolomide (TMZ) with metformin treatment was assessed by combination index analysis. Metformin could decrease cell viability, proliferation, and migration, increase cell apoptosis, and disrupt EMT in all three glioblastoma cell lines. The GSEA study highlighted increased ROS and hypoxia in the metformin-treated glioblastoma cells. Metformin increased ROS production, impaired mitochondrial membrane potential, and reduced mitochondrial biogenesis. The combined treatment of metformin and TMZ had U87 as synergistic, LNZ308 as antagonistic, and LN229 as additive. Metformin alone or combined with TMZ could suppress mitochondrial transcription factor A, Twist, and O⁶-methylguanine-DNA methyltransferase (MGMT) proteins in TMZ-resistant LN229 cells. In conclusion, our study showed that metformin decreased metabolic activity, proliferation, migration, mitochondrial biogenesis, and mitochondrial membrane potential and increased apoptosis and ROS in some glioblastoma cells. The sensitivity of the TMZ-resistant glioblastoma cell line to metformin might be mediated via the suppression of mitochondrial biogenesis, EMT, and MGMT expression. Our work provides new insights into the choice of adjuvant agents in TMZ-resistant GBM therapy.

The role of MicroRNA networks in tissue-specific direct and indirect effects of metformin and its application

Metformin is a first-line oral antidiabetic agent that results in clear benefits in relation to glucose metabolism and diabetes-related complications. The specific regulatory details and mechanisms underlying these benefits are still unclear and require further investigation. There is recent mounting evidence that metformin has pleiotropic effects on the target tissue development in metabolic organs, including adipose tissue, the gastrointestinal tract and the liver. The mechanism of actions of metformin are divided into direct effects on target tissues and indirect effects via non-targeted tissues. MicroRNAs (miRNAs) are a class of endogenous, noncoding, negative gene regulators that have emerged as important regulators of a number of diseases, including type 2 diabetes mellitus (T2DM). Metformin is involved in many aspects of miRNA regulation, and metformin treatment in T2DM should be associated with other miRNA targets. A large number of miRNAs regulation by metformin in target tissues with either direct or indirect effects has gradually been revealed in the context of numerous diseases and has gradually received increasing attention. This paper thoroughly reviews the current knowledge about the role of miRNA networks in the tissue-specific direct and indirect effects of metformin. Furthermore, this knowledge provides a novel theoretical basis and suggests therapeutic targets for the clinical treatment of metformin and miRNA regulators in the prevention and treatment of cancer, cardiovascular disorders, diabetes and its complications.

Chronic exposure to environmentally relevant concentrations of guanylurea induces neurotoxicity of Danio rerio adults

Recent studies have shown guanylurea (GUA) alters the growth and development of fish, induces oxidative stress, and disrupts the levels and expression of several genes, metabolites, and proteins related to the overall fitness of fish. Nonetheless, up to date, no study has assessed the potential neurotoxic effects that GUA may induce in non-target organisms. To fill the current knowledge gaps about the effects of this metabolite in the central nervous system of fish, we aimed to determine whether or not environmentally relevant concentrations of this metabolite may disrupt the behavior, redox status, AChE activity in Danio rerio adults. In addition, we also meant to assess if 25, 50, and 200 μg/L of GUA can alter the expression of several antioxidant defenses-, apoptosis-, AMPK pathway-, and neuronal communication-related genes in the brain of fish exposed for four months to GUA. Our results demonstrated that chronic exposure to GUA altered the swimming behavior of D. rerio, as fish remained more time frozen and traveled less distance in the tank compared to the control group. Moreover, this metabolite significantly increased the levels of oxidative damage biomarkers and inhibited the activity of acetylcholinesterase of fish in a concentration-dependent manner. Concerning gene expression, environmentally relevant concentrations of GUA downregulated the expression GRID2IP, PCDH17, and PCDH19, but upregulated Nrf1, Nrf2, p53, BAX, CASP3, PRKAA1, PRKAA2, and APP in fish after four months of exposure. Collectively, we can conclude that GUA may alter the homeostasis of several essential brain biomarkers, generating anxiety-like behavior in fish.

Metformin exerts an antitumoral effect on papillary thyroid cancer cells through altered cell energy metabolism and sensitized by BACH1 depletion

PURPOSE

Aberrant cell energy metabolism is one of the features of thyroid carcinogenesis. Metformin may reduce the risk of cancer, and BACH1 was reported to affect the sensitivity of cancer cells to metformin. The aims of this study were to investigate whether metformin exerts antitumor effects in PTC cells and explore the role of BACH1 depletion on the sensitivity of PTC cells to metformin.

METHODS

The viability and proliferation of PTC cell lines were analyzed with MTT and colony forming assay. Energy utilization and mitochondrial respiration were measured using Seahorse XF instruments and Mitochondrial complex-1 activity assay.

RESULTS

Our results showed the anti-proliferative and pro-apoptotic effects of metformin in PTC cells. Furthermore, metformin changed the pattern of cell energy metabolism in PTC cells, which manifested as inhibition of mitochondrial respiration, and the combination of BACH1 depletion with metformin magnified the effect of metformin alone.

CONCLUSIONS

In conclusion, metformin exerts an antitumoral effect on PTC cells both in vitro and in xenograft mouse models. A possible mechanism is through inhibiting glucose metabolism and mitochondrial respiration process. Knocking down BACH1 caused the switching of energy metabolism and sensitized PTC cells to metformin, which eventually enhanced the anti-tumor effect of metformin.

Microarray analysis of breast cancer gene expression profiling in response to 2-deoxyglucose, metformin, and glucose starvation

BACKGROUND

Breast cancer (BC) is the most frequently diagnosed cancer in women. Altering glucose metabolism and its effects on cancer progression and treatment resistance is an emerging interest in BC research. For instance, combining chemotherapy with glucose-lowering drugs (2-deoxyglucose (2-DG), metformin (MET)) or glucose starvation (GS) has shown better outcomes than with chemotherapy alone. However, the genes and molecular mechanisms that govern the action of these glucose deprivation conditions have not been fully elucidated. Here, we investigated the differentially expressed genes in MCF-7 and MDA-MB-231 BC cell lines upon treatment with glucose-lowering drugs (2-DG, MET) and GS using microarray analysis to study the difference in biological functions between the glucose challenges and their effect on the vulnerability of BC cells.

METHODS

MDA-MB-231 and MCF-7 cells were treated with 20 mM MET or 4 mM 2-DG for 48 h. GS was performed by gradually decreasing the glucose concentration in the culture medium to 0 g/L, in which the cells remained with fetal bovine serum for one week. Expression profiling was carried out using Affymetrix Human Clariom S microarrays. Differentially expressed genes were obtained from the Transcriptome Analysis Console and enriched using DAVID and R packages.

RESULTS

Our results showed that MDA-MB-231 cells were more responsive to glucose deprivation than MCF-7 cells. Endoplasmic reticulum stress response and cell cycle inhibition were detected after all three glucose deprivations in MDA-MB-231 cells and only under the metformin and GS conditions in MCF-7 cells. Induction of apoptosis and inhibition of DNA replication were observed with all three treatments in MDA-MB-231 cells and metformin-treated MCF-7 cells. Upregulation of cellular response to reactive oxygen species and inhibition of DNA repair mechanisms resulted after metformin and GS administration in MDA-MB-231 cell lines and metformin-treated MCF-7 cells. Autophagy was induced after 2-DG treatment in MDA-MB-231 cells and after metformin in MCF-7 cells. Finally, inhibition of DNA methylation were observed only with GS in MDA-MB-231 cells.

CONCLUSION

The procedure used to process cancer cells and analyze their expression data distinguishes our study from others. GS had the greatest effect on breast cancer cells compared to 2-DG and MET. Combining MET and GS could restrain both cell lines, making them more vulnerable to conventional chemotherapy.

A functional screen with metformin identifies microRNAs that regulate metabolism in colorectal cancer cells

Metformin inhibits oxidative phosphorylation and can be used to dissect metabolic pathways in colorectal cancer (CRC) cells. CRC cell proliferation is inhibited by metformin in a dose dependent manner. MicroRNAs that regulate metabolism could be identified by their ability to alter the effect of metformin on CRC cell proliferation. An unbiased high throughput functional screen of a synthetic micoRNA (miRNA) library was used to identify miRNAs that impact the metformin response in CRC cells. Experimental validation of selected hits identified miRNAs that sensitize CRC cells to metformin through modulation of proliferation, apoptosis, cell-cycle and direct metabolic disruption. Among eight metformin sensitizing miRNAs identified by functional screening, miR-676-3p had both pro-apoptotic and cell cycle arrest activity in combination with metformin, whereas other miRNAs (miR-18b-5p, miR-145-3p miR-376b-5p, and miR-718) resulted primarily in cell cycle arrest when combined with metformin. Investigation of the combined effect of miRNAs and metformin on CRC cell metabolism showed that miR-18b-5p, miR-145-3p, miR-376b-5p, miR-676-3p and miR-718 affected glycolysis only, while miR-1181 only regulated CRC respiration. MicroRNAs can sensitize CRC cells to the anti-proliferative effects of metformin. Identifying relevant miRNA targets may enable the design of innovative therapeutic strategies.

Demystifying the Relationship Between Metformin, AMPK, and Doxorubicin Cardiotoxicity

Doxorubicin (DOX) is an extremely effective and wide-spectrum anticancer drug, but its long-term use can lead to heart failure, which presents a serious problem to millions of cancer survivors who have been treated with DOX. Thus, identifying agents that can reduce DOX cardiotoxicity and concurrently enhance its antitumor efficacy would be of great clinical value. In this respect, the classical antidiabetic drug metformin (MET) has stood out, appearing to have both antitumor and cardioprotective properties. MET is proposed to achieve these beneficial effects through the activation of AMP-activated protein kinase (AMPK), an essential regulator of mitochondrial homeostasis and energy metabolism. AMPK itself has been shown to protect the heart and modulate tumor growth under certain conditions. However, the role and mechanism of the hypothesized MET-AMPK axis in DOX cardiotoxicity and antitumor efficacy remain to be firmly established by in vivo studies using tumor-bearing animal models and large-scale prospective clinical trials. This review summarizes currently available literature for or against a role of AMPK in MET-mediated protection against DOX cardiotoxicity. It also highlights the emerging evidence suggesting distinct roles of the AMPK subunit isoforms in mediating the functions of unique AMPK holoenzymes composed of different combinations of isoforms. Moreover, the review provides a perspective regarding future studies that may help fully elucidate the relationship between MET, AMPK and DOX cardiotoxicity.

Magnolol-loaded Cholesteryl Biguanide Conjugate Hydrochloride Nanoparticles for Triple-negative Breast Cancer Therapy

The potential of combination therapy using nanoparticle delivery systems in improving triple-negative breast cancer treatment efficacy remains to be explored. Here, we report a novel nanoparticle system using a cholesterol biguanide conjugate hydrochloride (CBH) as both a drug and carrier to load magnolol (MAG). Poly(ethylene glycol)-poly(lactic-co-glycolic acid) (mPEG-PLGA) and aminoethyl anisamide-poly(ethylene glycol)-poly(lactic-co-glycolic acid) (AEAA-PEG-PLGA) were added to form nanoparticles. Nanoparticles accumulated most in tumor tissues when the weight ratio of AEAA-PEG-PLGA to mPEG-PLGA was 4:1. MAG and CBH exerted a synergistic inhibitory effect on 4T1 cells. An in vitro study showed that nanoparticles displayed the highest tumor cell uptake rate, highest apoptosis rate, and strongest inhibitory effect on tumor cell migration and monoclonal formation. CBH might promote nanoparticle uptake by cells and lysosomal escape. After intravenous administration to mice with 4T1 breast tumors in situ, the nanoparticles inhibited tumor growth without obvious toxicity. Western blot results showed that nanoparticles altered the levels of p53, p-AKT, and p-AMPK in the tumor tissue. Moreover, cell apoptosis was found in the same area of H&E-stained and TUNEL-stained tumors treated with the nanoparticles. Collectively, this nanoparticle system provides a novel combination drug delivery strategy for treating triple-negative breast cancer.

MicroRNAs: Important Players in Breast Cancer Angiogenesis and Therapeutic Targets

The high incidence of breast cancer (BC) is linked to metastasis, facilitated by tumor angiogenesis. MicroRNAs (miRNAs or miRs) are small non-coding RNA molecules that have an essential role in gene expression and are significantly linked to the tumor development and angiogenesis process in different types of cancer, including BC. There's increasing evidence showed that various miRNAs play a significant role in disease processes; specifically, they are observed and over-expressed in a wide range of diseases linked to the angiogenesis process. However, more studies are required to reach the best findings and identify the link among miRNA expression, angiogenic pathways, and immune response-related genes to find new therapeutic targets. Here, we summarized the recent updates on miRNA signatures and their cellular targets in the development of breast tumor angiogenetic and discussed the strategies associated with miRNA-based therapeutic targets as anti-angiogenic response.

Metformin may induce ferroptosis by inhibiting autophagy via lncRNA H19 in breast cancer

Autophagy and ferroptosis have been major foci of biomedical research in recent years. Elucidation of their intrinsic molecular relationships is important for cancer prevention and treatment. Metformin can directly inhibit tumorigenesis, although the mechanism responsible for this is not fully understood. Here, we demonstrate that metformin and lncRNA‐H19 can regulate both autophagy and ferroptosis. Autophagy inducers and H19 can reverse the production of lipid reactive oxygen species and the inhibition of autophagy induced by metformin. The present study suggests that metformin may induce ferroptosis by inhibiting autophagy via H19, and this discovery may facilitate the development of novel therapies for the treatment of breast cancer.

Ozone induces BEL7402 cell apoptosis by increasing reactive oxygen species production and activating JNK

Background

Oxidative stress is an important factor in the modulation of both tumorigenesis and anticancer responses. Ozone (O₃) is a strong oxidant that causes redox reactions and exerts anticancer effects in various types of cancer cells. However, the pathways involved in O₃-induced cell death are not well understood.

Methods

In vitro human hepatocellular carcinoma (HCC) BEL7402 cells were treated with various O₃ concentrations to evaluate O₃ cytotoxicity by Cell Counting Kit-8 (CCK-8) assay and flow cytometry. The regulatory mechanisms were analyzed by western blot analysis. In vivo, an HCC model was established to evaluate the inhibition of HCC with O₃ treatment.

Results

In vitro cells treated with O₃ exhibited a round and small morphology with nuclear shrinkage and fragmentation. The CCK-8 assay confirmed the potent cytotoxic activity of O₃ against BEL7402 cells (IC₅₀ value of 5 µg/mL). Acridine orange/ethidium bromide (AO/EB) staining revealed apoptosis of BEL7402 cells after O₃ treatment. Flow cytometry analysis showed that S phase cell cycle arrest and apoptosis increased with O₃ exposure. In addition, O3 exposure reduced the mitochondrial membrane potential (ΔΨm) and induced reactive oxygen species (ROS) accumulation. Western blot analysis showed that O₃ exposure reduced B-cell lymphoma 2 (BCL-2) expression and increased cleaved poly ADP-ribose polymerase (PARP), cytochrome C (Cyt-C), caspase-3, caspase-9, and p-JNK expression. In vivo, treatment with intratumor injection O₃ (20 µg/mL) inhibited HCC growth.

Conclusions

Overall, our findings showed that O₃ induces BEL7402 cell apoptosis via the intrinsic mitochondria-dependent pathway. Therefore, O₃ has therapeutic potential for HCC.

Metformin attenuates the epithelial-mesenchymal transition of lens epithelial cells through the AMPK/TGF-β/Smad2/3 signalling pathway

Posterior capsule opacification (PCO) is a common ocular fibrosis disease related to the epithelial-mesenchymal transition (EMT) of human lens epithelial cells (HLECs). However, safe and effective drugs that prevent or treat PCO are lacking. Metformin (Mtf) has been used to treat fibrosis-related diseases affecting many organs and tissues, but its effect on ocular fibrosis-related diseases is unclear. We investigated whether Mtf can inhibit EMT and fibrosis in HLECs to prevent and treat PCO and elucidated the potential molecular mechanism. Here, we established an HLEC model of TGF-β-induced EMT and found that 400 μM Mtf inhibited vertical and lateral migration and EMT-related gene and protein expression in HLECs. Smad2/3 are downstream molecules of TGF-β that enter the nucleus to regulate EMT-related gene expression during the occurrence and development of PCO. We revealed that Mtf suppressed TGF-β-induced Smad2/3 phosphorylation and nuclear translocation. Mtf induces AMP-activated protein kinase (AMPK) phosphorylation. In this study, we found that Mtf induced the activation of AMPK phosphorylation in HLECs. To further explore the mechanism of Mtf, we pretreated HLECs with Compound C (an AMPK inhibitor) to repeat the above experiments and found that Compound C abolished the inhibitory effect of Mtf on HLEC EMT and the TGF-β/Smad2/3 signalling pathway. Thus, Mtf targets AMPK phosphorylation to inhibit the TGF-β/Smad2/3 signalling pathway and prevent HLEC EMT. Notably, we first illustrated the AMPK/TGF-β/Smad2/3 signalling pathway in HLECs, which may provide a new therapeutic strategy for PCO.

Pitavastatin and metformin synergistically activate apoptosis and autophagy in pancreatic cancer cells

Pancreatic cancer is the seventh leading cause of cancer-related deaths globally. Metformin is the standard first-line of treatment for hyperglycemia in Type 2 diabetes, whereas pitavastatin is a cholesterol-lowering drug used to prevent cardiovascular diseases. Both these agents evidently exert anticancer effects on pancreatic cancer; however, it remains unclear whether cotreatment using them has additive or synergistic anticancer effects on pancreatic cancer. Thus, we herein used the ASPC-1 and PANC-1 cells and treated them with metformin and/or pitavastatin. We performed the cell viability assay, transwell migration assay, and cell cycle analysis using flow cytometry. Western blotting was used to determine protein levels. We found that cotreatment with metformin (30 mM) and pitavastatin (10 μM) significantly reduced cell viability; caused G0/G1 cell cycle arrest; upregulated the expression levels of Bax, PCNA, cleaved PARP-1, cleaved caspase-3, LC3 II, and p27 ^Kip1 /p21^Cip1 ; and inhibited cell migration. The combination index value for cell viability indicated a synergistic interaction between metformin and pitavastatin. Moreover, cotreating the cells with metformin (30 mM) and pitavastatin (10 μM) could preserve mitochondrial function, activate AMPK, and inhibit PI3K/mTOR than treatment with metformin or pitavastatin alone. These findings clearly indicated that metformin plus pitavastatin had a synergistic anticancer effect on pancreatic cancer cells, potentially caused due to the activation of AMPK and inhibition of PI3K/mTOR signaling. Altogether, our results provide that use of metformin plus pitavastatin maybe serve as a chemotherapeutic agent for human pancreatic cancer in future.

MicroRNA-216b targets HK2 to potentiate autophagy and apoptosis of breast cancer cells via the mTOR signaling pathway

Patients suffering from breast cancer (BC) still have a poor response to treatments, even though early detection and improved therapy have contributed to a reduced mortality. Recent studies have been inspired on the association between microRNAs (miRs) and therapies of BC. The current study set out to investigate the role of miR-216b in BC, and further analyze the underlining mechanism. Firstly, hexokinase 2 (HK2) and miR-216b were characterized in BC tissues and cells by RT-qPCR and Western blot assay. In addition, the interaction between HK2 and miR-216b was analyzed using dual luciferase reporter assay. BC cells were further transfected with a series of miR-126b mimic or inhibitor, or siRNA targeting HK2, so as to analyze the regulatory mechanism of miR-216b, HK2 and mammalian target of rapamycin (mTOR) signaling pathway, and to further explore their regulation in BC cellular behaviors. The results demonstrated that HK2 was highly expressed and miR-216b was poorly expressed in BC cells and tissues. HK2 was also verified as a target of miR-216b with online databases and dual luciferase reporter assay. Functionally, miR-216b was found to be closely associated with BC progression via inactivating mTOR signaling pathway by targeting HK2. Moreover, cell viability, migration and invasion were reduced as a result of miR-216b upregulation or HK2 silencing, while autophagy, cell cycle arrest and apoptosis were induced. Taken together, our findings indicated that miR-216 down-regulates HK2 to inactivate the mTOR signaling pathway, thus inhibiting the progression of BC. Hence, this study highlighted a novel target for BC treatment.

Long non-coding RNA NEAT1 absorbs let-7 g-5p to induce epithelial-mesenchymal transition of colon cancer cells through upregulating BACH1

OBJECTIVE

Long noncoding RNAs (lncRNAs) are critical regulators in diverse human cancers. However, the role of lncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) in colon cancer remains to be further investigated. We aimed to verify the role of NEAT1/let-7 g-5p/BTB and CNC homology 1 (BACH1) axis in colon cancer development.

METHODS

Expression of NEAT1, let-7 g-5p and BACH1 in colon cancer tissues and cells was determined. The interactions between NEAT1 and let-7 g-5p, and between let-7 g-5p and BACH1 were assessed. The colon cancer cell lines were treated with plasmids or oligonucleotides to alter NEAT1, BACH1 and let-7 g-5p expression. Then, viability, migration, invasion, and apoptosis of colon cells were evaluated, and the cell growth in vivo was observed as well.

RESULTS

NEAT1 and BACH1 were upregulated while let-7 g-5p was downregulated in colon cancer tissues and cells. NEAT1/BACH1 silencing or let-7 g-5p elevation suppressed colon cancer cell growth in vivo and in vitro. The effects of silenced NEAT1 on colon cancer cells and xenografts were reversed by downregulating let-7 g-5p. Down-regulation of BACH1 reversed the effect of NEAT1 overexpression on colon cancer cells. NEAT1 directly bound to let-7 g-5p and let-7 g-5p targeted BACH1.

CONCLUSION

Downregulated NEAT1 elevated let-7 g-5p to suppress EMT of colon cancer cells through inhibiting BACH1. This research may contribute to treatment of colon cancer.

Anti-cancer effect of metformin on the metastasis and invasion of primary breast cancer cells through mediating NF-kB activity

Current evidence strongly suggests that aberrant activation of the nuclear factor kappa B (NF-kB) signaling cascade is connected to carcinogenesis. The matrix metalloproteinases (MMP) which are also the key agents for tumor metastasis may be potent candidates for tumor diagnosis in clinics. In this in vitro study, we hypothesized that metformin with an effective dose can inhibit tumor cell proliferation and metastasis by modulating the expressions of MMP-2 and -9 and interfering with NF-kB signaling in primary breast cancer cells (PBCCs). 300 000 cells per ml were obtained from biopsies of breast tumors from five human donors. The cell viability and proliferation were tested. Immunocytochemistry was performed for MMP-2, MMP-9, and NF-kB, and enzyme-linked immunosorbent assay for NF-kB activity, quantitative real-time PCR for RELA/p65, IkBα, MMP-2, and MMP-9. Three different doses of metformin (5, 10, and 25 mM) (Met) reduced the viability and proliferation of PBCCs in a dose-dependent manner, maximum inhibition was observed at 25 mM Met. The expression of RELA/p65 was not affected by 25 mM Met. Nuclear immunoreactivity and activity of NF-kB reduced while cytoplasmic NF-kB (p65) elevated by 25 mM Met compared to non-treatment (P <  0.05). The expression and immunoreactivity of MMP-9 but not MMP-2 were decreased by 25 mM Met treatment, compared with the non-treatment (P <  0.05). Metformin may have an essential antitumor role in the invasion and metastasis pathways of PBCCs by downregulating the MMP-9 expression blocking both the activity and nuclear translocation of NF-kB.

Metabolic Classification and Intervention Opportunities for Tumor Energy Dysfunction

A comprehensive view of cell metabolism provides a new vision of cancer, conceptualized as tissue with cellular-altered metabolism and energetic dysfunction, which can shed light on pathophysiological mechanisms. Cancer is now considered a heterogeneous ecosystem, formed by tumor cells and the microenvironment, which is molecularly, phenotypically, and metabolically reprogrammable. A wealth of evidence confirms metabolic reprogramming activity as the minimum common denominator of cancer, grouping together a wide variety of aberrations that can affect any of the different metabolic pathways involved in cell physiology. This forms the basis for a new proposed classification of cancer according to the altered metabolic pathway(s) and degree of energy dysfunction. Enhanced understanding of the metabolic reprogramming pathways of fatty acids, amino acids, carbohydrates, hypoxia, and acidosis can bring about new therapeutic intervention possibilities from a metabolic perspective of cancer.

How metformin affects various malignancies by means of microRNAs: a brief review

Metformin known as the first-line orally prescribed drug for lowering blood glucose in type II diabetes (T2DM) has recently found various therapeutic applications including in cancer. Metformin has been studied for its influences in prevention and treatment of cancer through multiple mechanisms such as microRNA (miR) regulation. Alteration in the expression of miRs by metformin may play an important role in the treatment of various cancers. MiRs are single-stranded RNAs that are involved in gene regulation. By binding to the 3'UTR of target mRNAs, miRs influence protein levels. Irregularities in the expression of miRs that control the expression of oncogenes and tumor suppressor genes are associated with the onset and progression of cancer. Metformin may possess an effect on tumor prevention and progression by modifying miR expression and downstream pathways. Here, we summarize the effect of metformin on different types of cancer by regulating the expression of various miRs and the associated downstream molecules.

Liraglutide, a TFEB-Mediated Autophagy Agonist, Promotes the Viability of Random-Pattern Skin Flaps

Random skin flaps are commonly used in reconstruction surgery. However, distal necrosis of the skin flap remains a difficult problem in plastic surgery. Many studies have shown that activation of autophagy is an important means of maintaining cell homeostasis and can improve the survival rate of flaps. In the current study, we investigated whether liraglutide can promote the survival of random flaps by stimulating autophagy. Our results show that liraglutide can significantly improve flap viability, increase blood flow, and reduce tissue oedema. In addition, we demonstrated that liraglutide can stimulate angiogenesis and reduce pyroptosis and oxidative stress. Through immunohistochemistry analysis and Western blotting, we verified that liraglutide can enhance autophagy, while the 3-methylladenine- (3MA-) mediated inhibition of autophagy enhancement can significantly reduce the benefits of liraglutide described above. Mechanistically, we showed that the ability of liraglutide to enhance autophagy is mediated by the activation of transcription factor EB (TFEB) and its subsequent entry into the nucleus to activate autophagy genes, a phenomenon that may result from AMPK-MCOLN1-calcineurin signalling pathway activation. Taken together, our results show that liraglutide is an effective drug that can significantly improve the survival rate of random flaps by enhancing autophagy, inhibiting oxidative stress in tissues, reducing pyroptosis, and promoting angiogenesis, which may be due to the activation of TFEB via the AMPK-MCOLN1-calcineurin signalling pathway.

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.

Cyclovirobuxine D Induces Apoptosis and Mitochondrial Damage in Glioblastoma Cells Through ROS-Mediated Mitochondrial Translocation of Cofilin

Background

Cyclovirobuxine D (CVBD), a steroidal alkaloid, has multiple pharmacological activities, including anti-cancer activity. However, the anti-cancer effect of CVBD on glioblastoma (GBM) has seldom been investigated. This study explores the activity of CVBD in inducing apoptosis of GBM cells, and examines the related mechanism in depth.

Methods

GBM cell lines (T98G, U251) and normal human astrocytes (HA) were treated with CVBD. Cell viability was examined by CCK-8 assay, and cell proliferation was evaluated by cell colony formation counts. Apoptosis and mitochondrial superoxide were measured by flow cytometry. All protein expression levels were determined by Western blotting. JC-1 and CM-H₂DCFDA probes were used to evaluate the mitochondrial membrane potential (MMP) change and intracellular ROS generation, respectively. The cell ultrastructure was observed by transmission electron microscope (TEM). Colocalization of cofilin and mitochondria were determined by immunofluorescence assay.

Results

CVBD showed a greater anti-proliferation effect on the GBM cell lines, T98G and U251, than normal human astrocytes in dose- and time-dependent manners. CVBD induced apoptosis and mitochondrial damage in GBM cells. We found that CVBD led to mitochondrial translocation of cofilin. Knockdown of cofilin attenuated CVBD-induced apoptosis and mitochondrial damage. Additionally, the generation of ROS and mitochondrial superoxide was also induced by CVBD in a dose-dependent manner. N-acetyl-L-cysteine (NAC) and mitoquinone (MitoQ) pre-treatment reverted CVBD-induced apoptosis and mitochondrial damage. MitoQ pretreatment was able to block the mitochondrial translocation of cofilin caused by CVBD.

Conclusions

Our data revealed that CVBD induced apoptosis and mitochondrial damage in GBM cells. The underlying mechanism is related to mitochondrial translocation of cofilin caused by mitochondrial oxidant stress.

Betulinic Acid Restricts Human Bladder Cancer Cell Proliferation In Vitro by Inducing Caspase-Dependent Cell Death and Cell Cycle Arrest, and Decreasing Metastatic Potential

Betulinic acid (BA) is a naturally occurring pentacyclic triterpenoid and generally found in the bark of birch trees (Betula sp.). Although several studies have been reported that BA has diverse biological activities, including anti-tumor effects, the underlying anti-cancer mechanism in bladder cancer cells is still lacking. Therefore, this study aims to investigate the anti-proliferative effect of BA in human bladder cancer cell lines T-24, UMUC-3, and 5637, and identify the underlying mechanism. Our results showed that BA induced cell death in bladder cancer cells and that are accompanied by apoptosis, necrosis, and cell cycle arrest. Furthermore, BA decreased the expression of cell cycle regulators, such as cyclin B1, cyclin A, cyclin-dependent kinase (Cdk) 2, cell division cycle (Cdc) 2, and Cdc25c. In addition, BA-induced apoptosis was associated with mitochondrial dysfunction that is caused by loss of mitochondrial membrane potential, which led to the activation of mitochondrial-mediated intrinsic pathway. BA up-regulated the expression of Bcl-2-accociated X protein (Bax) and cleaved poly-ADP ribose polymerase (PARP), and subsequently activated caspase-3, -8, and -9. However, pre-treatment of pan-caspase inhibitor markedly suppressed BA-induced apoptosis. Meanwhile, BA did not affect the levels of intracellular reactive oxygen species (ROS), indicating BA-mediated apoptosis was ROS-independent. Furthermore, we found that BA suppressed the wound healing and invasion ability, and decreased the expression of Snail and Slug in T24 and 5637 cells, and matrix metalloproteinase (MMP)-9 in UMUC-3 cells. Taken together, this is the first study showing that BA suppresses the proliferation of human bladder cancer cells, which is due to induction of apoptosis, necrosis, and cell cycle arrest, and decrease of migration and invasion. Furthermore, BA-induced apoptosis is regulated by caspase-dependent and ROS-independent pathways, and these results provide the underlying anti-proliferative molecular mechanism of BA in human bladder cancer cells.

Metformin exhibits antiproliferation activity in breast cancer via miR-483-3p/METTL3/m6A/p21 pathway

Evidence suggests that metformin might be a potential candidate for breast cancer treatment. Yet, its relevant molecular mechanisms remain to be fully investigated. We found that metformin could suppress the N6-methyladenosine (m6A) level in breast cancer cells significantly. The latter has an essential role in breast cancer progression and is newly considered as a therapeutic target. In this study, we measured the m6A level by m6A colorimetric analysis and dot blot assay. We then performed qRT-PCR, western blot, MeRIP, dual-luciferase reporter assay, and others to explore the m6A-dependent pathway associated with metformin. In vivo effect of metformin was investigated using a mouse tumorigenicity model. In addition, breast cancer and normal tissues were used to determine the role of METTL3 in breast cancer. Metformin could reduce the m6A level via decreasing METTL3 expression mediated by miR-483-3p in breast cancer. METTL3 is known to be able to promote breast cancer cell proliferation by regulating the p21 expression by an m6A-dependent manner. Metformin can take p21 as the main target to inhibit such effect. To specify, this study exhibited that metformin can inhibit breast cancer cell proliferation through the pathway miR-483-3p/METTL3/m6A/p21. Our findings suggest that METTL3 may be considered as a potential therapeutic target of metformin for breast cancer.

Effect of Metformin on Breast Density in Overweight/Obese Premenopausal Women

BACKGROUND

This study investigated the effects of metformin on breast density in overweight/obese premenopausal women.

METHODS

Overweight/obese premenopausal women (n=120) were randomly assigned to the metformin or placebo group, and all women received lifestyle interventions. The outcomes included weight, BMI, FPG, FIN, glucose, HOMA-IR, LDL-C, HDL-C, TG, TC, SBP, DBP, FSH, E, AD, and the BIRADS grade, and the incidence of breast cancer was assessed by pathological biopsy and BIRADS grade greater than 4.

RESULTS

In total, 120 overweight/obese women completed the 1-year trial. Seven patients had a BIRADS grade greater than 4, including 5 patients who were biopsy positive, in the control group, and 2 patients had a BIRADS grade greater than 4, including 1 patient who was biopsy positive, in the metformin group. Compared with those in the control group, the body weight, BMI, FIN, FPG, HOMA-IR, TC, BIRADS grade and positive pathological biopsy rate in the metformin group were significantly decreased (P<0.05), while AD was significantly increased (P<0.05). The correlation analysis indicated that the BIRADS grade was significantly correlated with weight, BMI, FPG, FIN, HOMA-IR, SBP, AD and the positive pathological biopsy rate, and the positive pathological biopsy rate was significantly correlated with weight, BMI, HOMA-IR, SBP, AD and BIRADS grade. The logistic regression analysis revealed that the BIRADS grade was significantly correlated with the positive pathological biopsy rate and AD and that the positive pathological biopsy rate was significantly correlated with the BIRADS grade.

CONCLUSION

As adjunctive therapy, the combination of lifestyle changes and metformin was found to be a safe strategy for improving related metabolic markers and increasing adiponectin. The BIRADS grade was significantly correlated with the positive pathological biopsy rate and AD, and the positive pathological biopsy rate was significantly correlated with the BIRADS grade.

Novel organo-osmium(ii) proteosynthesis inhibitors active against human ovarian cancer cells reduce gonad tumor growth inCaenorhabditis elegans

Novel Os(ii) arene complexes with a deprotonated ppy or ppy-CHO C^N ligand have been synthesized to selectively act on cancer cells as proteosynthesis inhibitorsin vitroand exert antitumor activityin vivoinC. elegansmodels.

Mechanisms of action of metformin and its regulatory effect on microRNAs related to angiogenesis

Angiogenesis is rapidly initiated in response to pathological conditions and is a key target for pharmaceutical intervention in various malignancies. Anti-angiogenic therapy has emerged as a potential and effective therapeutic strategy for treating cancer and cardiovascular-related diseases. Metformin, a first-line oral antidiabetic agent for type 2 diabetes mellitus (T2DM), not only reduces blood glucose levels and improves insulin sensitivity and exerts cardioprotective effects but also shows benefits against cancers, cardiovascular diseases, and other diverse diseases and regulates angiogenesis. MicroRNAs (miRNAs) are endogenous noncoding RNA molecules with a length of approximately 19-25 bases that are widely involved in controlling various human biological processes. A large number of miRNAs are involved in the regulation of cardiovascular cell function and angiogenesis, of which miR-21 not only regulates vascular cell proliferation, migration and apoptosis but also plays an important role in angiogenesis. The relationship between metformin and abnormal miRNA expression has gradually been revealed in the context of numerous diseases and has received increasing attention. This paper reviews the drug-target interactions and drug repositioning events of metformin that influences vascular cells and has benefits on angiogenesis-mediated effects. Furthermore, we use miR-21 as an example to explain the specific molecular mechanism underlying metformin-mediated regulation of the miRNA signaling pathway controlling angiogenesis and vascular protective effects. These findings may provide a new therapeutic target and theoretical basis for the clinical prevention and treatment of cardiovascular diseases.

Oxidative Stress and Cancer Development: Are Noncoding RNAs the Missing Links?

Significance: It is now clear that genetic changes underlie the basis of cancer, and alterations in functions of multiple genes are responsible for the process of tumorigenesis. Besides the classical genes that are usually implicated in cancer, the role of noncoding RNAs (ncRNAs) and reactive oxygen species (ROS) as independent entitites has also been investigated. Recent Advances: The microRNAs and long noncoding RNAs (lncRNAs), two main classes of ncRNAs, are known to regulate many aspects of tumor development. ROS, generated during oxidative stress and pathological conditions, are known to regulate every step of tumor development. Conversely, oxidative stress and ROS producing agents can suppress tumor development. The malignant cells normally produce high levels of ROS compared with normal cells. The interaction between ROS and ncRNAs regulates the expression of multiple genes and pathways implicated in cancer, suggesting a unique mechanistic relationship among ncRNA-ROS-cancer. The mechanistic relationship has been reported in hepatocellular carcinoma, glioma, and malignancies of blood, breast, colorectum, esophagus, kidney, lung, mouth, ovary, pancreas, prostate, and stomach. The ncRNA-ROS regulate several cancer-related cell signaling pathways, namely, protein kinase B (AKT), epidermal growth factor receptor (EGFR), forkhead box O3 (FOXO3), kelch-like ECH-associated protein 1 (Keap1), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), nuclear factor erythroid 2-related factor 2 (Nrf2), p53, phosphatase and tensin homologue (PTEN), and wingless-related integration site (Wnt)/glycogen synthase kinase-3 beta (GSK3β). Critical Issues: To date, most of the reports about ncRNA-oxidative stress-carcinogenesis relationships are based on cell lines. The mechanistic basis for this relationship has not been completely elucidated. Future Directions: Attempts should be made to explore the association of lncRNAs with ROS. The significance of the ncRNA-oxidative stress-carcinogenesis interplay should also be explored through studies in animal models.

Inhibition of JNK-Mediated Autophagy Promotes Proscillaridin A- Induced Apoptosis via ROS Generation, Intracellular Ca+2 Oscillation and Inhibiting STAT3 Signaling in Breast Cancer Cells

Breast cancer is the most heterogenous cancer type among women across the world. Despite concerted efforts, breast cancer management is still unsatisfactory. Interplay between apoptosis and autophagy is an imperative factor in categorizing therapeutics for cancer treatment. Proscillaridin A (PSD-A), a well-known cardiac glycoside used for cardiac arrest and arrythmias, has been unveiled in many cancer types but the underlying mechanism for apoptosis and autophagy in breast cancer is not fully understood. In our study, PSD-A restricted cell growth, inhibited STAT3 activation and induced apoptosis and autophagy in breast cancer cells via ROS generation and Ca⁺² oscillation. Pretreatment of NAC and BAPTA-AM restored PSD-A induced cellular events in breast cancer cells. PSD-A induced apoptosis via DNA fragmentation, caspase-cascade activation, PARP cleavage, mitochondrial dysfunction, Bax/Bcl-2 proteins modulation and ER chaperone GRP78 inhibition along with decreased phosphorylation of ERK1/2. Inhibition of STAT3 activation was found to be associated with decreased phosphorylation of SRC. Moreover, PSD-A induced events of autophagy i.e. conversion of LC3-I to LC3-II, and Atg3 expression via JNK activation and decreased mTOR and AKT phosphorylation. In this study, pretreatment of SP600125, a JNK inhibitor, reduced autophagy and enhanced STAT3 inhibition and apoptosis. Additionally, SB203580, a commercial p38 inhibitor, stimulated STAT3 activation and improved autophagic events rate in breast cancer cells, displaying the role of the MAPK signaling pathway in interplay between apoptosis and autophagy. Our data suggest that the rate of apoptotic cell death is improved by blocking JNK-induced autophagy in PSD-A treated MCF-7 and MDA-MB-231 breast cancer cells.