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

The effect of SP/NK1R on expression and activity of glutaredoxin and thioredoxin proteins in prostate cancer cells

Substance P (SP), an important neuropeptide, has a crucial role in the progression of several cancers, including prostate cancer, through interacting with the neurokinin-1 receptor (NK1R). Oxidative stress is also involved in the onset and progression of prostate cancer. However, no studies have been performed on the cross-talk between the SP/NK1R system and cellular redox balance in prostate cancer, and how it is involved in tumorogenesis. We aimed to investigate the effect of the SP/NK1R system and the blockage of NK1R with its specific antagonist (aprepitant) on the cellular redox status of the prostate cancer cell line (PC3 and LNCaP). We performed the resazurin assay to evaluate the toxicity of the aprepitant on the PC3 and LNCaP cell lines. The intracellular reactive oxygen species (ROS) level was measured after SP and aprepitant treatment. The alterations of expression and activity of two crucial cellular oxidoreductases, glutaredoxin, and thioredoxin were evaluated by qRT-PCR and commercial kits (ZellBio GmbH), respectively. Our results revealed that SP increased ROS production and decreased the expression and activity of glutaredoxin and thioredoxin. On the other hand, treatment of cells with aprepitant showed reverse results. In conclusion, we found that the SP/NK1R system could promote prostate cancer progression by inducing oxidative stress. In addition, the inhibition of NK1R by aprepitant modulated the effect of the SP/NK1R system on the cellular redox system. Aprepitant might therefore be introduced as a candidate for the treatment of prostate cancer; however, more studies are required to confirm the validation of this hypothesis.

Current findings on the antitumor effects of metformin on esophageal squamous cell carcinoma (Review)

Esophageal squamous cell carcinoma (ESCC) is an intractable type of cancer that requires novel therapeutic modalities, since the therapeutic outcomes are often inadequate, even in response to multidisciplinary treatment. The antitumor effect of metformin, an antidiabetic drug, has been reported in esophageal cancer; however, its effects are diverse. Since various multidisciplinary therapies are used in ESCC, the antitumor effect of metformin is expected to be synergistic in some treatment strategies. The present review summarizes the antitumor effects of metformin and discusses its use in combination with existing therapies. The present study reviewed relevant studies where the molecular targets of metformin (AMPK and inflammatory system signals) were described, followed by the classification and organization of its antitumor effects, and subsequently summarized the current research on its antitumor effects, especially in ESCC. A number of studies have reported that metformin prevents the development of ESCC and exerts its antitumor effects through various pathways. In addition, metformin has been shown to inhibit tumor growth, induce apoptosis, inhibit cancer cell invasion, migration and angiogenesis into the tumor, and decrease tumor malignancy, such as metastasis. Furthermore, it may modulate host tumor immunity in a tumor-suppressive manner and is expected to improve prognosis following treatment for ESCC. Notably, metformin may be beneficial in combination with chemotherapy, such as cisplatin, and radiation. By contrast, it has been shown to potentially induce resistance to 5-fluorouracil. Finally, the effects of metformin in combination with other therapies are discussed in the present study, and perspectives on the potential benefits of metformin for future ESCC treatment are presented. In conclusion, the present review may be useful in improving the understanding of the wide range of antitumor effects of metformin. Although some concerning points remain, using metformin in ESCC treatment could be promising. Notably, more knowledge needs to be accumulated regarding the effects of metformin on ESCC.

Effects of metformin on cancers in experimental and clinical studies: Focusing on autophagy and AMPK/mTOR signaling pathways

Metformin (MET) is a preferred drug for the treatment of type 2 diabetes mellitus. Recent studies show that apart from its blood glucose-lowering effects, it also inhibits the development of various tumours, by inducing autophagy. Various studies have confirmed the inhibitory effects of MET on cancer cell lines' propagation, migration, and invasion. The objective of the study was to comprehensively review the potential of MET as an anticancer agent, particularly focusing on its ability to induce autophagy and inhibit the development and progression of various tumors. The study aimed to explore the inhibitory effects of MET on cancer cell proliferation, migration, and invasion, and its impact on key signaling pathways such as adenosine monophosphate-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), and PI3K. This review noted that MET exerts its anticancer effects by regulating key signalling pathways such as phosphoinositide 3-kinase (PI3K), LC3-I and LC3-II, Beclin-1, p53, and the autophagy-related gene (ATG), inhibiting the mTOR protein, downregulating the expression of p62/SQSTM1, and blockage of the cell cycle at the G0/G1. Moreover, MET can stimulate autophagy through pathways associated with the 5' AMPK, thereby inhibiting he development and progression of various human cancers, including hepatocellular carcinoma, prostate cancer, pancreatic cancer, osteosarcoma, myeloma, and non-small cell lung cancer. In summary, this detailed review provides a framework for further investigations that may appraise the autophagy-induced anticancer potential of MET and its repurposing for cancer treatment.

Metformin in Esophageal Carcinoma: Exploring Molecular Mechanisms and Therapeutic Insights

Esophageal cancer (EC) remains a formidable malignancy with limited treatment options and high mortality rates, necessitating the exploration of innovative therapeutic avenues. Through a systematic analysis of a multitude of studies, we synthesize the diverse findings related to metformin's influence on EC. This review comprehensively elucidates the intricate metabolic pathways and molecular mechanisms through which metformin may exert its anti-cancer effects. Key focus areas include its impact on insulin signaling, AMP-activated protein kinase (AMPK) activation, and the mTOR pathway, which collectively contribute to its role in mitigating esophageal cancer progression. This review critically examines the body of clinical and preclinical evidence surrounding the potential role of metformin, a widely prescribed anti-diabetic medication, in EC management. Our examination extends to the modulation of inflammation, oxidative stress and angiogenesis, revealing metformin's potential as a metabolic intervention in esophageal cancer pathogenesis. By consolidating epidemiological and clinical data, we assess the evidence that supports metformin's candidacy as an adjuvant therapy for esophageal cancer. By summarizing clinical and preclinical findings, our review aims to enhance our understanding of metformin's role in EC management, potentially improving patient care and outcomes.

Metformin in therapeutic applications in human diseases: its mechanism of action and clinical study

Metformin, a biguanide drug, is the most commonly used first-line medication for type 2 diabetes mellites due to its outstanding glucose-lowering ability. After oral administration of 1 g, metformin peaked plasma concentration of approximately 20-30 μM in 3 h, and then it mainly accumulated in the gastrointestinal tract, liver and kidney. Substantial studies have indicated that metformin exerts its beneficial or deleterious effect by multiple mechanisms, apart from AMPK-dependent mechanism, also including several AMPK-independent mechanisms, such as restoring of redox balance, affecting mitochondrial function, modulating gut microbiome and regulating several other signals, such as FBP1, PP2A, FGF21, SIRT1 and mTOR. On the basis of these multiple mechanisms, researchers tried to repurpose this old drug and further explored the possible indications and adverse effects of metformin. Through investigating with clinical studies, researchers concluded that in addition to decreasing cardiovascular events and anti-obesity, metformin is also beneficial for neurodegenerative disease, polycystic ovary syndrome, aging, cancer and COVID-19, however, it also induces some adverse effects, such as gastrointestinal complaints, lactic acidosis, vitamin B12 deficiency, neurodegenerative disease and offspring impairment. Of note, the dose of metformin used in most studies is much higher than its clinically relevant dose, which may cast doubt on the actual effects of metformin on these disease in the clinic. This review summarizes these research developments on the mechanism of action and clinical evidence of metformin and discusses its therapeutic potential and clinical safety.

Targeting the SOX2/PARP1 complex to intervene in the growth of esophageal squamous cell carcinoma

Elevated SOX2 protein levels are closely correlated with the increased incidence of esophageal squamous cell carcinoma (ESCC). However, establishing effective target measures for ESCC treatments continue to be researched. It has been previously proposed that SOX2 represents a potential therapeutic target for ESCC. Here, we found that the enzyme Poly(ADP-Ribose) polymerase 1 (PARP1) enriched in ESCCs interact with SOX2. Inhibition of PARP1 with 3-aminobenzamide (3-ABA) or shRNA knockdown reduced the proliferation of ESCCs, accompanied by decreased protein levels of SOX2. RNA sequencing demonstrated that PARP1 inhibition affected multiple signaling pathways involved in cancer cell proliferation. Additionally, 3-ABA synergistically suppressed the growth of ESCC cells when combined with cisplatin, and metformin potentiated the suppressive effect of 3-ABA on ESCC cell growth. Together these findings suggest that targeting SOX2 binding partner PARP1 provides a possible avenue to treat patients with high levels of SOX2.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

The Chemosensitizing Role of Metformin in Anti-Cancer Therapy

Chemoresistance, which leads to the failure of chemotherapy and further tumor recurrence, presents the largest hurdle for the success of anti-cancer therapy. In recent years, metformin, a widely used first-line antidiabetic drug, has attracted increasing attention for its anti-cancer effects. A growing body of evidence indicates that metformin can sensitize tumor responses to different chemotherapeutic drugs, such as hormone modulating drugs, anti-metabolite drugs, antibiotics, and DNA-damaging drugs via selective targeting of Cancer Stem Cells (CSCs), improving the hypoxic microenvironment, and by suppressing tumor metastasis and inflammation. In addition, metformin may regulate metabolic programming, induce apoptosis, reverse Epithelial to Mesenchymal Transition (EMT), and Multidrug Resistance (MDR). In this review, we summarize the chemosensitization effects of metformin and focus primarily on its molecular mechanisms in enhancing the sensitivity of multiple chemotherapeutic drugs, through targeting of mTOR, ERK/P70S6K, NF-κB/HIF-1 α, and Mitogen- Activated Protein Kinase (MAPK) signaling pathways, as well as by down-regulating the expression of CSC genes and Pyruvate Kinase isoenzyme M2 (PKM2). Through a comprehensive understanding of the molecular mechanisms of chemosensitization provided in this review, the rationale for the use of metformin in clinical combination medications can be more systematically and thoroughly explored for wider adoption against numerous cancer types.>.

Metformin's Effects on Apoptosis of Esophageal Carcinoma Cells and Normal Esophageal Epithelial Cells: An In Vitro Comparative Study

The effect of metformin on human esophageal normal and carcinoma cells remains poorly understood. We aim to investigate the different antiproliferation effects and underlying distinct molecular mechanisms between these two types of cells. Human esophageal squamous cell carcinoma cell line, EC109, and normal esophageal epithelial cell line, HEEC, were used in the experiment. The cell survival rate was determined by cell counting kit-8 (CCK-8). Cell apoptosis was analyzed by flow cytometry. The mRNA and protein levels of signal transducer and activator of transcription 3 (Stat3) were detected by real-time quantitative PCR and western blot. Interleukin-6 (IL-6) was added to activate Stat3. The level of intracellular reactive oxygen species (ROS) was assessed by a DCFH-DA fluorescent probe. Metformin had more significant inhibitory effects on cell proliferation in EC109 cells than HEECs. Metformin induced apoptosis of EC109 cells in a dose-dependent manner instead of HEECs. The expression of Stat3 in both mRNA and protein levels was higher in EC109 cells than HEECs. Further study revealed that metformin may attenuate the phosphorylation of the Stat3 and the Bcl-2 expression, which was restored by IL-6 partly in EC109 cells but not HEECs. On the contrary, metformin increased the level of ROS in both the cell lines, but this intracellular ROS variation had no effect on apoptosis. Metformin has different functional roles on the apoptosis in esophageal carcinoma cells and normal esophageal cells. Therefore, the Stat3/Bcl-2 pathway-mediated apoptosis underlies the cell-type-specific drug sensitivity, suggesting metformin possesses a therapeutic activity and selectivity on esophageal cancer.

Role of p53 Family Proteins in Metformin Anti-Cancer Activities

Metformin has been used as therapy for type 2 diabetes for many years. Clinical and basic evidence as indicated that metformin has anti-cancer activities. It has been well-established that metformin activates AMP-activated protein kinase (AMPK), which in turn regulates energy homeostasis. However, the mechanistic aspects of metformin anti-cancer activity remain elusive. p53 family proteins, including p53, p63 and p73, have diverse biological functions, including regulation of cell growth, survival, development, senescence and aging. In this review, we highlight the evidence and mechanisms by which metformin inhibits cancer cell survival and tumor growth. We also aimed to discuss the role of p53 family proteins in metformin-mediated suppression of cancer growth and survival.

Heme Oxygenase-1 Inhibition Sensitizes Human Prostate Cancer Cells towards Glucose Deprivation and Metformin-Mediated Cell Death

High levels of heme oxygenase (HO)-1 have been frequently reported in different human cancers, playing a major role in drug resistance and regulation of cancer cell redox homeostasis. Metformin (MET), a drug widely used for type 2 diabetes, has recently gained interest for treating several cancers. Recent studies indicated that the anti-proliferative effects of metformin in cancer cells are highly dependent on glucose concentration. The present work was directed to determine whether use of a specific inhibitor of HO-1 activity, alone or in combination with metformin, affected metastatic prostate cancer cell viability under different concentrations of glucose. MTT assay and the xCELLigence system were used to evaluate cell viability and cell proliferation in DU145 human prostate cancer cells. Cell apoptosis and reactive oxygen species were analyzed by flow cytometry. The activity of HO-1 was inhibited using a selective imidazole-based inhibitor; genes associated with antioxidant systems and cell death were evaluated by qRT-PCR. Our study demonstrates that metformin suppressed prostate cancer growth in vitro and increased oxidative stress. Disrupting the antioxidant HO-1 activity, especially under low glucose concentration, could be an attractive approach to potentiate metformin antineoplastic effects and could provide a biochemical basis for developing HO-1-targeting drugs against solid tumors.

Melatonin suppresses thyroid cancer growth and overcomes radioresistance via inhibition of p65 phosphorylation and induction of ROS

Thyroid cancer is the most common endocrine carcinoma with increasing incidence worldwide and anaplastic subtypes are frequently associated with cancer related death. Radioresistance of thyroid cancer often leads to therapy failure and cancer-related death. In this study, we found that melatonin showed potent suppressive roles on NF-κB signaling via inhibition of p65 phosphorylation and generated redox stress in thyroid cancer including the anaplastic subtypes. Our data showed that melatonin significantly decreased cell viability, suppressed cell migration and induced apoptosis in thyroid cancer cell lines in vitro and impaired tumor growth in the subcutaneous mouse model in vivo. By contrast, irradiation of thyroid cancer cells resulted in elevated level of phosphorylated p65, which could be reversed by cotreatment with melatonin. Consequently, melatonin synergized with irradiation to induce cytotoxicity to thyroid cancer, especially in the undifferentiated subgroups. Taken together, our results suggest that melatonin may exert anti-tumor activities against thyroid carcinoma by inhibition of p65 phosphorylation and induction of reactive oxygen species. Radio-sensitization by melatonin may have clinical benefits in thyroid cancer.