Metformin inhibits the proliferation of A431 cells by modulating the PI3K/Akt signaling pathway

Mechanism of Asperosaponin VI Related to EGFR/MMP9/AKT/PI3K Pathway in Treatment of Rheumtoid Arthritis

OBJECTIVE

To explore the mechanism of action of asperosaponin VI (AVI) in the treatment of rheumatoid arthritis (RA) and validate it in ex vivo experiments using network pharmacology and molecular docking methods.

METHODS

The predicted targets of AVI were obtained from PharmMaper, UniProt and SwissTarget Prediction platforms, the disease targets were collected from Online Mendelian Inheritance in Man, Therapeutic Target Database and GeneCards databases, the intersection targets of AVI and RA were obtained from Venny 2.1.0, and the protein-protein interaction (PPI) network was obtained from STRING database, which was analyzed by Cytoscape software and screened to obtain the core targets. Cytoscape software was used to analyze PPI network and screen the core targets. Based on the Database for Annotation, Visualization and Integrated Discovery database, Gene Ontology functional and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis were performed, and Cytoscape software was used to construct the "Disease-Pathway-Target-Drug" network, which was finally verified by molecular docking and animal experiments.

RESULTS

Network pharmacological studies showed that AVI was able to modulate 289 targets, with 102 targets for the potential treatment of RA, with the core pathway being the AKT/PI3K signaling pathway, and the core targets being the epidermal growth factor receptor (EGFR) and matrix metalloproteinase 9 (MMP9). Molecular docking results showed that AVI could produce strong binding with both of the 2 core targets. In vitro cellular experiments showed that AVI reduced nitric oxide, prostaglandin E2, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and IL-1 β levels (P<0.05) and inhibited cyclooxygenase-2, nitric oxide synthase, EGFR, MMP9, phosphorylated phosphoinositide 3-kinase (p-PI3K), and phosphorylated serine-threonine kinase (p-AKT) proteins (P<0.05). The results of in vivo studies showed that AVI improved RA score and foot swelling thickness and decreased TNF-α, IL-6, p-PI3K and p-AKT levels in RA rats (P<0.05).

CONCLUSION

AVI exerts anti-inflammatory and anti-RA effects which might be related to the EGFR/MMP9/AKT/PI3K pathway.

Monoolein-based nanodispersions for cutaneous co-delivery of methylene blue and metformin: Thermal and structural characterization and effects on the cutaneous barrier, skin penetration and cytotoxicity

This study evaluated the potential of monoolein (MO)-based nanodispersions to promote the cutaneous co-delivery of metformin (MET) and methylene blue (MB) for the treatment of non-melanoma skin cancer. MO-based nanodispersions were obtained using Kolliphor® P407 (KP) and/or sodium cholate (CH), and characterized concerning the structure, thermal stability, ability to disrupt the skin barrier, cutaneous permeation and retention of MB and MET. Additionally, the cytotoxic effect of MO nanodispersions-mediated combination therapy using MET and MB in A431 cells was evaluated. The nanodispersions exhibited nanometric size (<200 nm) and thermal and physical stability. Small angle X-ray scattering studies revealed multiple structures depending on composition. They were able to interact with stratum corneum lipid structure, increasing its fluidity. The effect of MO-nanodispersions on topical/transdermal delivery of MB and MET was composition-dependent. Nanodispersions with low MO content (5 %) and stabilized with KP and CH (0.05-0.10 %) were the most promising, enhancing the cutaneous delivery of MB and MET by 1.9 to 2.2-fold and 1.4 to 1.7-fold, respectively, compared to control. Cytotoxic studies revealed that the most promising MO nanodispersion-mediated combination therapy using MET and MB (1:1) reduced the IC₅₀ by 24-fold, compared to MB solution, and a further reduction (1.5-fold) was observed by MB photoactivation.

Regulatory Basis of Adipokines Leptin and Adiponectin in Epilepsy: from Signaling Pathways to Glucose Metabolism

Epilepsy is a common and severe neurological disorder in which impaired glucose metabolism leads to changes in neuronal excitability that slow or promote the development of epilepsy. Leptin and adiponectin are important mediators regulating glucose metabolism in the peripheral and central nervous systems. Many studies have reported a strong association between epilepsy and these two adipokines involved in multiple signaling cascades and glucose metabolism. Due to the complex regulatory mechanisms between them and various signal activation networks, their role in epilepsy involves many aspects, including the release of inflammatory mediators, oxidative damage, and neuronal apoptosis. This paper aims to summarize the signaling pathways involved in leptin and adiponectin and the regulation of glucose metabolism from the perspective of the pathogenesis of epilepsy. In particular, we discuss the dual effects of leptin in epilepsy and the relationship between antiepileptic drugs and changes in the levels of these two adipokines. Clinical practitioners may need to consider these factors in evaluating clinical drugs. Through this review, we can better understand the specific involvement of leptin and adiponectin in the pathogenesis of epilepsy, provide ideas for further exploration, and bring about practical significance for the treatment of epilepsy, especially for the development of personalized treatment according to individual metabolic characteristics.

A preliminary analysis of prognostic genes in advanced laryngeal squamous cell carcinoma patients with postoperative radiotherapy

Advanced laryngeal squamous cell carcinoma (LSCC) has a high mortality rate, and the prognosis is poor. However, the underlying molecular biological mechanisms bringing about the development and progression of advanced LSCC are not entirely clarified. This study aimed to find out the potential biomarkers to predict the prognosis in advanced LSCC patients who had undergone postoperative radiotherapy alone. The next-generation sequencing of RNA was performed to detect the mRNAs expression profiling in 10 advanced LSCC samples, comprised of 5 samples from LSCC patients with favorable outcome and 5 samples from paired patients with poor outcome. Then bioinformatics analysis including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway were used to find out functional core genes that were significantly different between the two groups. 1630 differentially expressed genes (DEGs) were confirmed to have significant differences between the two groups. 53 GO terms and 19 pathways which were closely related to the DEGs were identified. Finally, 52 intersection DEGs which were both related to the top three GO terms and pathways were identified. The expression of several core genes was confirmed with RT-qPCR in tissues from another 75 patients. RT-qPCR confirmed that the genes of c-JUN, LYN, PIK3R2, and TNFAIP3 were significantly differentially expressed between the two groups, which was in accordance with the RNA sequencing data. The DEGs identified above may be potential prognostic markers for advanced LSCC patients with postoperative radiotherapy, and may provide essential guidance for following-up.

Metformin Potentiates the Anticancer Effect of Everolimus on Cervical Cancer In Vitro and In Vivo

Simple Summary

Recent studies have shown that metformin combined with clinical chemotherapeutic drugs could cause decreased cell toxicity and attenuate tumor resistance in various types of cancer. The aim of the present study was to elucidate whether combined treatment with metformin and everolimus has a synergistic anticancer effect in human cervical cancer in vitro and in vivo. The results showed that this combined treatment synergistically inhibited the growth of human cervical cancer cell lines and xenografts in nude mice, and induced caspase-dependent apoptosis, promoting sub-G1- and G0/G1-phase arrest and enhancing mtROS production. Combined treatment also synergistically inactivated PI3K/AKT signaling and activated MAPKs signaling in cervical cancer. Our data suggested that metformin potentiates the anticancer effect of everolimus on cervical cancer, and combined treatment provides a novel therapeutic strategy for patients with cervical cancer.

Abstract

Cervical cancer is globally the fourth most common cancer in women. Metformin is a widely used drug for the treatment of type II diabetes and has been shown to possess important anticancer properties in cervical cancer. Everolimus is an mTOR inhibitor and is widely used to treat NETs, RCC, TSC, and breast cancers. The present study investigated the anticancer effects of metformin and everolimus in cervical cancer, when used alone or in combination. CaSki and C33A human cervical cancer cells were treated with different concentrations of everolimus alone or in combination with metformin. Cell viability was assessed using a CCK-8 assay. Cell apoptosis, cell-cycle, and mtROS analyses were conducted using flow cytometry. Target protein levels were analyzed by Western blotting. Related mechanisms were confirmed using appropriate inhibitors (z-VAD-fmk and BIRB796). The in vitro results were further confirmed in a xenograft tumor study. Both metformin and everolimus, when used alone, were moderately effective in inhibiting cell proliferation and inducing cell apoptosis of CaSki and C33A cells. When used in combination, these two drugs synergistically inhibited the growth of human cervical cancer cells and xenografts in nude mice, promoted sub-G1- and G0/G1-phase cell-cycle arrest, and enhanced mtROS production. The protein expressions of PI3K (p110α) and p-AKT were significantly downregulated, while P27, P21, p-p38, p-ERK, and p-JNK were upregulated following combined treatment. These results revealed that metformin potentiates the anticancer effect of everolimus on cervical cancer, and combination treatment with metformin and everolimus provides a novel therapeutic strategy for patients with cervical cancer.

Postnatal metformin treatment alters rat Sertoli cell proliferation and daily sperm production

BACKGROUND

The direct correlation between Sertoli cell number and sperm production capacity highlights the importance of deciphering external factors that modify Sertoli cell proliferation. A growing body of evidence in vitro suggests that metformin, the main pharmacological agent for type 2 diabetes treatment in children, exerts anti-proliferative effects on Sertoli cells.

OBJECTIVE

The aims of this study were to investigate the effect of metformin administration during postnatal period on Sertoli cell proliferation and on cell cycle regulators expression and to analyze the impact of this treatment on the sperm production capacity in adulthood.

MATERIALS AND METHODS

Sprague Dawley rat pups were randomly divided into two groups: MET (receiving daily 200 mg/kg metformin, from Pnd3 to Pnd7 inclusive) and control (receiving vehicle). BrdU incorporation was measured to assess proliferation. Gene expression analyses were performed in Sertoli cells isolated from animals of both groups. Daily sperm production and sperm parameters were measured in adult male rats (Pnd90) that received neonatal treatment.

RESULTS

MET group exhibited a significant decrease in BrdU incorporation in Sertoli cells. Concordantly, MET group showed a reduction in cyclin D1 and E2 expression and an increase in p21 expression in Sertoli cells. In addition, metformin-treated animals displayed lower values of daily sperm production on Pnd90.

DISCUSSION AND CONCLUSION

These results suggest that metformin treatment may lead to a decrease in Sertoli cell proliferation, a concomitant altered expression of cell cycle regulators and ultimately, a reduction in daily sperm production in adult animals.

The Effect of Astaxanthin and Metformin on Oxidative Stress in Granulosa Cells of BALB C Mouse Model of Polycystic Ovary Syndrome

Reactive oxygen species (ROS), involved in the pathogenesis of the polycystic ovary syndrome (PCOS), play a key role in the onset of apoptosis in follicles and granulosa cells (GCs). We aimed to investigate the antioxidant effects of AST and metformin separately and in combination on GCs using a PCOS mouse model. Forty-eight prepubertal female BALB C mice aged 25-30 days and weighing 12-14 g were studied. The PCOS model was created by subcutaneous injection of the dehydroepiandrosterone (DHEA) hormone in 8 mice of BALB C for 20 consecutive days. Apoptosis and the amount of ROS were evaluated in GCs of the ovaries via flow cytometry. The activity of AKT protein was measured by western blot, and the viability of GCs was investigated using spectrophotometry. Ovarian tissue sections were prepared, stained with H&E, and the morphology of the sections was examined. Statistical analysis was performed by SPSS v22.0 software using one-way ANOVA. We found that AST administration leads to a significant reduction in oxidative stress (P<0.01) and consequently a significant decrease in the rate of apoptosis (P<0.01). While the expression of AKT in the AST group revealed a significant increase (P<0.05), it decreased in the metformin group. However, it was still significantly higher than the control and PCOS groups. Ovulation was confirmed in both metformin and AST groups. Further studies are warranted to prove the efficacy of AST and to introduce it as a complementary therapeutic agent in PCOS.

FLT3 Inhibitors in Acute Myeloid Leukemia: Challenges and Recent Developments in Overcoming Resistance

Mutations in the FMS-like tyrosine kinase 3 (FLT3) gene are often present in newly diagnosed acute myeloid leukemia (AML) patients with an incidence rate of approximately 30%. Recently, many FLT3 inhibitors have been developed and exhibit positive preclinical and clinical effects against AML. However, patients develop resistance soon after undergoing FLT3 inhibitor treatment, resulting in short durable responses and poor clinical effects. This review will discuss the main mechanisms of resistance to clinical FLT3 inhibitors and summarize the emerging strategies that are utilized to overcome drug resistance. Basically, medicinal chemistry efforts to develop new small-molecule FLT3 inhibitors offer a direct solution to this problem. Other potential strategies include the combination of FLT3 inhibitors with other therapies and the development of multitarget inhibitors. It is hoped that this review will provide inspiring insights into the discovery of new AML therapies that can eventually overcome the resistance to current FLT3 inhibitors.

Changes in protein expression due to metformin treatment and hyperinsulinemia in a human endometrial cancer cell line

The incidence of endometrial cancer (EC) has increased over the past years and mainly affects women above the age of 45 years. Metabolic diseases such as obesity and type II diabetes mellitus as well as associated conditions like polycystic ovary syndrome (PCOS), insulin resistance and hyperinsulinemia lead to elevated levels of circulating estrogens. Increased estrogen concentrations, in turn, further trigger the proliferation of endometrial cells and thus promote EC development and progression, especially in the absence of progesterone as seen in postmenopausal women. Elevated blood glucose levels in diabetic patients further contribute to the risk of EC development. Metformin is an insulin-sensitizing biguanide drug, commonly used in the treatment of type II diabetes mellitus, especially in obese patients. Besides its effects on glucose metabolism, metformin displayed anti-cancer effects in various cancer types, including EC. Direct anti-cancer effects of metformin target signaling pathways that are involved in cellular growth and proliferation, e.g. the AKT/PKB/mTOR pathway. Further proteins and pathways have been suggested as potential targets, but the underlying mechanism of action of metformin's anti-cancer activity is still not completely understood. In the present study, the effects of metformin on protein expression were investigated in the human EC cell line HEC-1A using an affinity proteomic approach. Cells were treated with 0.5 mmol/L metformin over a period of 7 days and changes in the expression pattern of 1,300 different proteins were compared to the expression in untreated control cells as well as insulin-treated cells. Insulin treatment (100 ng/mL) was incorporated into the study in order to implement a model for insulin resistance and associated hyperinsulinemia, conditions that are often observed in obese and diabetic patients. Furthermore, the culture medium was supplemented with 10 nmol/L ß-estradiol (E2) during treatments to mimic increased estrogen levels, a common risk factor for EC development. Based on the most prominent and significant changes in expression, a set of 80 proteins was selected and subjected to a more detailed analysis. The data revealed that metformin and insulin targeted similar pathways in the present study and mostly acted on proteins related to proliferation, migration and tumor immune response. These pathways may be affected in a tumor-promoting as well as a tumor-suppressing way by either metformin treatment or insulin supplementation. The consequences for the cells resulting from the detected expression changes were discussed in detail for several proteins. The presented data helps identify potential targets affected by metformin treatment in EC and allows for a better understanding of the mechanism of action of the biguanide drug's anti-cancer activity. However, further investigations are necessary to confirm the observations and conclusions drawn from the presented data after metformin administration, especially for proteins that were regulated in a favorable way, i.e. AKT3, CCND2, CD63, CD81, GFAP, IL5, IL17A, IRF4, PI3, and VTCN1. Further proteins might be of interest, where metformin counteracted unfavorable effects that have been induced by hyperinsulinemia.

Developing an analytical method by HPLC for simultaneous quantification of methylene blue and metformin applied to in vitro skin permeation and retention studies

The aim of this study was to develop an HPLC method for simultaneous quantification of metformin (MET) and methylene blue (MB) in in vitro skin permeation/retention studies, in which retention was evaluated in the different layers of the skin [stratum corneum (SC) and the viable epidermis + dermis (VE + D)]. The method was validated considering the following parameters: specificity, linearity, quantitation limit (LOQ), recovery, precision and accuracy. Calibration curves were obtained using the following six matrices: methanol, water, methanolic extracts from the SC and VE + D spiked with the drugs and drugs extracted from the SC and VE + D. The precision, accuracy and LOQ of the method were evaluated in water and in VE + D and SC, applying the drug extraction process. The results show that the method is selective and linear for both drugs. The precision and accuracy values, independent of matrix and drug, were below the limit of 15%. The LOQ of MB was defined as 0.4 μg/ml in the VE + D and SC and 0.8 μg/ml in water. The LOQ of MET was defined as 0.8 μg/ml in the VE + D and SC and 0.4 μg/ml in the water. The recovery of the method was adequate, consistent and reproducible for the concentration range of 0.4-10 μg/ml for MB (73.3-92.1%) and 0.8-10.0 μg/mL for MET (72.4-94.4%). This method has a potential application in the development of formulation for skin delivery of MB and MET.

Antineoplastic Activity of an Old Natural Antidiabetic Biguanoid on the Human Thyroid Carcinoma Cell Line

BACKGROUND

In the last decades, metformin (Met), an herbal anti-diabetic medicine, has been proposed as an anti-cancer agent.

OBJECTIVE

Thyroid cancers are the most common malignancy of the endocrine system. Therefore, the current study was performed to assess the effects of Met on cell proliferation and activation of the Phosphoinositide 3-Kinase (PI3K)/Protein kinase B (AKT)/Forkhead Box O1 (FOXO1) signaling pathway in the Medullary Thyroid Carcinoma (MTC) cells. The effects of Met on the expression of REarranged during Transfection (RET) proto-oncogene were also investigated.

METHODS

MTC cell line (TT) was treated with 0, 2.5, 5, 10, 20, 30, 40, 50, and 60 mM concentrations of Met for 24, 48, and 72h. The viability and apoptosis of the treated cells were measured by the 3-(4,5-Dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) and Annexin V- Propidium Iodide (PI) assays. The expression level of PI3K, AKT, FOXO1, and RET genes was investigated by quantitative Real-Time Polymerase Chain Reaction (qRT-PCR), and phosphorylation of their proteins was determined by the Enzyme-Linked Immunosorbent Assay (ELISA).

RESULTS

Results showed that Met significantly decreased the viability of the MTC cells. Met also reduced the expression level of PI3K, AKT, and FOXO1 genes (P<0.05), whereas it elevated the expression level of RET proto-oncogene (P<0.05).

CONCLUSION

It seems that the Met has cytostatic effect on the TT cells. Our results showed that anti-tumoral effects of Met may be cell type-specific, and according to the induction of RET (as a proto-oncogene) and inhibition of FOXO1 (as a tumor suppressor gene), Met could not be an appropriate agent in treatment of MTC. The antineoplastic activity of Met has been confirmed against several malignancies in 'in vitro' and 'in vivo' studies. However, its molecular mechanisms in the treatment of different carcinomas particularly in thyroid cancers are not clearly understood and more studies are required to confirm its exact effect on the MTC.

Targeting AKT/mTOR in Oral Cancer: Mechanisms and Advances in Clinical Trials

Oral cancer (OC) is a devastating disease that takes the lives of lots of people globally every year. The current spectrum of treatment modalities does not meet the needs of the patients. The disease heterogeneity demands personalized medicine or targeted therapies. Therefore, there is an urgent need to identify potential targets for the treatment of OC. Abundant evidence has suggested that the components of the protein kinase B (AKT)/ mammalian target of rapamycin (mTOR) pathway are intrinsic factors for carcinogenesis. The AKT protein is central to the proliferation and survival of normal and cancer cells, and its downstream protein, mTOR, also plays an indispensable role in the cellular processes. The wide involvement of the AKT/mTOR pathway has been noted in oral squamous cell carcinoma (OSCC). This axis significantly regulates the various hallmarks of cancer, like proliferation, survival, angiogenesis, invasion, metastasis, autophagy, and epithelial-to-mesenchymal transition (EMT). Activated AKT/mTOR signaling is also associated with circadian signaling, chemoresistance and radio-resistance in OC cells. Several miRNAs, circRNAs and lncRNAs also modulate this pathway. The association of this axis with the process of tumorigenesis has culminated in the identification of its specific inhibitors for the prevention and treatment of OC. In this review, we discussed the significance of AKT/mTOR signaling in OC and its potential as a therapeutic target for the management of OC. This article also provided an update on several AKT/mTOR inhibitors that emerged as promising candidates for therapeutic interventions against OC/head and neck cancer (HNC) in clinical studies.

MUL1 E3 ligase regulates the antitumor effects of metformin in chemoresistant ovarian cancer cells via AKT degradation

Chemoresistance is one of most critical clinical problems encountered when treating patients with ovarian cancer, due to the fact that the disease is usually diagnosed at advanced stages. Metformin is used as a first‑line drug for the treatment of type 2 diabetes; however, drug repositioning studies have revealed its antitumor effects, mainly mediated through AMP‑activated protein kinase (AMPK) activation and AKT/mammalian target of rapamycin (mTOR) pathway inhibition in various types of cancer, including drug‑resistant cancer cells. The current study revealed that the novel antitumor mechanism of metformin is mediated by regulation of mitochondrial E3 ubiquitin protein ligase 1 (MUL1) expression that negatively regulates AKT. The results demonstrated that metformin decreased the expression of AKT protein levels via MUL1 E3 ligase. In addition, metformin increased both mRNA and protein levels of MUL1 and promoted degradation of AKT in a proteasome‑dependent manner. Silencing MUL1 expression suppressed the metformin‑mediated AKT degradation and its downstream effects. Cell cycle analysis and a clonogenic assay demonstrated that knockdown of MUL1 significantly diminished the antitumor effects of metformin. Together, these data indicate that MUL1 regulates metformin‑mediated AKT degradation and the antitumor effects of metformin in chemoresistant ovarian cancer cell lines.

A unified mitochondria mechanistic target of rapamycin acyl-coenzyme A dehydrogenase 10 signal relay modulation for metformin growth inhibition in human immortalized keratinocytes cells

Metformin exhibits antiproliferative and proapoptotic effects in a variety of diseases, characterized by malignant and nonmalignant hyperplastic cells; however, the underlying molecular mechanism of metformin in psoriasis has not been elucidated. In the current study, we found that after metformin treatment the proliferation of human immortalized keratinocytes (HaCaT) was significantly inhibited, while cell apoptosis was increased in a dose-dependent manner, accompanied with enhanced protein expression of acyl-coenzyme A dehydrogenase 10 (ACAD10). Furthermore, mechanism analysis revealed that ACAD10 expression is induced by downregulated activities of mechanistic target of rapamycin 1 (mTORC1) signaling rather than AMP-activated protein kinase signaling. The inactivation of mTORC1 by rapamycin pretreatment or rotenone-induced mitochondrial complex inhibition showed a similar effect because of the metformin treatment on the proliferation and apoptosis of HaCaT keratinocytes. Overexpression of mTORC1 almost reversed the antiproliferation and proapoptosis effects induced by metformin. This study showed that the metformin treatment inhibited HaCaT cells proliferation and promoted apoptosis by affecting the mitochondrial-mTORC1 signaling and elevated the ACAD10 expression. Hence, metformin can be used as a potential therapeutic agent for psoriasis.

Metformin attenuates hypoxia-induced resistance to cisplatin in the HepG2 cell line

Hepatoblastoma is the most commonly occurring liver tumor in children. Preoperative chemotherapy and surgery have improved treatment outcomes; however, further improvements are required in the treatment of advanced cases. Recently, the efficacy of transarterial chemoembolization (TACE) has garnered attention. TACE increases the local concentration of drugs by transcatheterically administering antitumor agents, and induces necrosis in the tumor by embolizing the feeding artery. However, studies have revealed that tumors exhibit resistance to anticancer drugs in hypoxic environments. Metformin is a drug used to treat type 2 diabetes; however, recent reports have indicated that it may also exhibit antitumor effects in various cancer cell lines. These effects are hypothesized to be mediated by the activation of adenosine monophosphate-activated protein kinase and reduction of mammalian target of rapamycin signaling, but these effects occur at high concentrations that are not suitable for use in a clinical setting. The potential efficacy of metformin at increased physiological concentrations has not been evaluated. The present study investigated the therapeutic effect of low concentrations of metformin in combination with cisplatin on liver cancer HepG2 cells in hypoxic conditions. HepG2 cells were treated with cisplatin alone, metformin alone, or a combination of these two drugs and cultured in normoxia or hypoxia. Treatment with either 5 µM cisplatin or 1 mM metformin alone did not significantly affect cell proliferation or apoptosis in hypoxic conditions. However, when 5 µM cisplatin was combined with 1 mM metformin, a significant inhibition of cell proliferation and induction of apoptosis was observed in hypoxic HepG2 cells. In conclusion, a low concentration of metformin attenuates hypoxia-induced resistance to cisplatin in HepG2 cells. Selective delivery of an effective dose of metformin to a hepatoblastoma tumor may be achievable and clinically useful with TACE.

Effects of metformin on the PI3K/AKT/FOXO1 pathway in anaplastic thyroid Cancer cell lines

Background

The PI3K/AKT/FOXO signaling pathway plays an important role in the survival, proliferation and apoptosis of tumor cells. The aim of the present study was to explore whether metformin could affect insulin-promoting cell growth by regulation of this pathway.

Material and methods

Anaplastic thyroid cancer cells were treated with 0–60 mM metformin for 24, 48 and 72 h. Cell viability, morphology, apoptosis and migration were investigated by MTT assay, microscopy observation, AnexinV-PI and the wound healing assay, respectively. Expression levels of PI3K, AKT and FOXO1 were detected by RT-qPCR, and proteins phosphorylated levels were determined by ELISA.

Results

Metformin decreased cell viability and migration in a significant time-and dose-dependent manner, and induced apoptosis and morphological changes in the cells. RT-qPCR results showed that expression levels of PI3K, AKT and FOXO1 was inhibited by metformin (P < 0.05). However, there was no significant change in the expression level of AKT following metformin treatment for C643 cell line (P > 0.05). ELISA results showed that metformin treatment had no significant effects on the phosphorylated levels of PI3K, AKT and FOXO1 (P > 0.05).

Conclusuion

The downregulation of FOXO1 was intensified by metformin, but no increase in cell viability was observed following FOXO1 downregulation by metformin. However, the exact molecular mechanism of metformin on inhibition of the PI3K/AKT pathway and subsequent decrease in cell viability remains unclear and further studies are required for its clarification.

Electronic supplementary material

The online version of this article (10.1007/s40199-018-0208-2) contains supplementary material, which is available to authorized users.

Metabolic changes associated with metformin potentiates Bcl-2 inhibitor, Venetoclax, and CDK9 inhibitor, BAY1143572 and reduces viability of lymphoma cells

Metformin exerts direct anti-tumor effects by activating AMP-activated protein kinase (AMPK), a major sensor of cellular metabolism in cancer cells. This, in turn, inhibits pro-survival mTOR signaling. Metformin has also been shown to disrupt complex 1 of the mitochondrial electron transport chain. Here, we explored the lymphoma specific anti-tumor effects of metformin using Daudi (Burkitt), SUDHL-4 (germinal center diffuse large B-cell lymphoma; GC DLBCL), Jeko-1 (Mantle-cell lymphoma; MCL) and KPUM-UH1 (double hit DLBCL) cell lines. We demonstrated that metformin as a single agent, especially at high concentrations produced significant reductions in viability and proliferation only in Daudi and SUDHL-4 cell lines with associated alterations in mitochondrial oxidative and glycolytic metabolism. As bcl-2 proteins, cyclin dependent kinases (CDK) and phosphoinositol-3- kinase (PI3K) also influence mitochondrial physiology and metabolism with clear relevance to the pathogenesis of lymphoma, we investigated the potentiating effects of metformin when combined with novel agents Venetoclax (bcl-2 inhibitor), BAY-1143572 (CDK9 inhibitor) and Idelalisib (p110δ- PI3K inhibitor). Co-treating KPUM-UH1 and SUDHL-4 cells with 10 mM of metformin resulted in 1.4 fold and 8.8 fold decreases, respectively, in IC-50 values of Venetoclax. By contrast, 3-fold and 10 fold reduction in IC-50 values of BAY-1143572 in Daudi and Jeko-1 cells respectively was seen in the presence of 10 mM of metformin. No change in IC-50 value for Idelalisib was observed across cell lines. These data suggest that although metformin is not a potent single agent, targeting cancer metabolism with similar but more effective drugs in novel combination with either bcl-2 or CDK9 inhibitors warrants further exploration.

MicroRNA-126 affects rheumatoid arthritis synovial fibroblast proliferation and apoptosis by targeting PIK3R2 and regulating PI3K-AKT signal pathway

Rheumatoid arthritis (RA) is a chronic autoimmune disease that causes inflammation and destruction of the joints as well as an increased risk of cardiovascular disease. RA synovial fibroblasts (RASFs) are involved in the progression of RA and release pro-inflammatory cytokines. On the other hand, microRNAs (miRs) may help control the inflammatory response of immune and non-immune cells. Therefore, our study used lentiviral expression vectors to test the effects of miR-126 overexpression on RASF proliferation and apoptosis. Luciferase experiments verified the targeting relationship between miR-126 and PIK3R2 gene. The co-transfection of anti-miR-126 and PIK3R2 siRNA to RASFs were used to identify whether PIK3R2 was directly involved in proliferation and apoptosis of miR-126-induced RASFs. Real-time polymerase chain reaction (PCR) was used to detect miR-126 and PIK3R2 expressions. MTT assay was used to detect cell proliferation. Flow cytometry was used to detect cell apoptosis and cell cycle. Western blotting was used to detect PIK3R2, PI3K, AKT and p-AKT proteins. After Lv-miR-126 infected RASFs, the relative expression of miR-126 was significantly enhanced. MiR-126 promoted RASF proliferation and inhibited apoptosis. Levels of PIK3R2 decreased while total PI3K and p-AKT levels increased in RASFs overexpressing miR-126. Co-transfection of anti-miR-126 and PIK3R2 siRNA also increased PI3K and p-AKT levels as well as RASF proliferation and reduced apoptosis, as compared to anti-miR-126 treatment alone. Finally, luciferase reporter assays showed that miR-126 targeted PIK3R2. Our data indicate that miR-126 overexpression in RASFs inhibits PIK3R2 expression and promotes proliferation while inhibiting apoptosis. This suggests inhibiting miR-126 may yield therapeutic benefits in the treatment of RA.

Anti-tumoral effects of exercise on hepatocellular carcinoma growth

Regular physical exercise has many beneficial effects, including antitumor properties, and is associated with a reduced risk of developing hepatocellular carcinoma (HCC). Less is known about the impact of exercise on HCC growth and progression. Here, we investigated the effects of exercise on HCC progression and assessed whether any beneficial effects would be evident under sorafenib treatment and could be mimicked by metformin. American Cancer Institute rats with orthotopic syngeneic HCC derived from Morris Hepatoma‐3924A cells were randomly assigned to exercise (Exe) and sedentary groups, or sorafenib±Exe groups or sorafenib±metformin groups. The Exe groups ran on a motorized treadmill for 60 minutes/day, 5 days/week for 4 weeks. Tumor viable area was decreased by exercise, while cell proliferation and vascular density were reduced. Exercise increased the expression of phosphatase and tensin homolog deleted from chromosome 10 and increased the phosphorylation of adenosine monophosphate‐activated protein kinase, while the phosphorylation of protein kinase B, S6 ribosomal protein, and signal transducer and activator of transcription 3 were decreased. Transcriptomic analysis suggested major effects of exercise were on nontumoral liver rather than tumor tissue. Exercise demonstrated similar effects when combined with sorafenib. Moreover, similar effects were observed in the group treated with sorafenib+metformin, revealing an exercise‐mimicking effect of metformin. Conclusion: Exercise attenuates HCC progression associated with alterations in key signaling pathways, cellular proliferation, tumor vascularization, and necrosis. These beneficial effects are maintained when combined with sorafenib and can be mimicked by metformin. (Hepatology Communications 2018;2:607‐620)

Metformin inhibits the migration and invasion of esophageal squamous cell carcinoma cells by downregulating the protein kinase B signaling pathway

Previous studies have suggested that metformin, a biguanide family member widely used as an oral antidiabetic drug, may inhibit proliferation and induce apoptosis in certain types of cancer cell. However, the molecular mechanisms underlying metformin-associated anticancer effects, and in particular antimetastatic effects, remain to be fully understood. The present study assessed the efficacy of metformin in inhibiting the migration and invasion of the esophageal carcinoma cell line EC109, and evaluated the effect of metformin on the protein kinase B (AKT) signaling pathway. EC109 cells were treated with 0, 5, 10 or 20 mM metformin during the logarithmic growth phase. A Transwell assay and western blot analysis revealed that metformin inhibited the migration and invasion of EC109 cells, nuclear factor-κB activation, matrix metallopeptidase 9 and N-cadherin expression in a phosphorylated-AKT dependent manner. These results suggested that metformin inhibits the migration and invasion of human esophageal carcinoma cells by suppressing AKT phosphorylation and regulating the expression of migration- and invasion-associated genes.

The co-treatment of metformin with flavone synergistically induces apoptosis through inhibition of PI3K/AKT pathway in breast cancer cells

Metformin, a widely used antidiabetic drug, exhibits anticancer effects which are mediated by the phosphatidylinositol 3-kinase (PI3K)/serine/threonine kinase (AKT) signaling pathway. However, its use in anticancer therapy combined with other natural products remains unclear. Flavone as the core structure of flavonoids has been demonstrated to induce cell apoptosis without causing serious side effect. Murine double minute X (MDMX) inhibits tumor suppressor gene p53 whose function is associated with the PI3K/AKT pathway. The results presented herein revealed that the combination of metformin and flavone significantly inhibited cell viability, and increased apoptosis of human breast cancer cells compared with metformin or flavone alone. The combination decreased the protein expression of MDMX, activated p53 through the PI3K/AKT signaling pathway, regulated p53 downstream target genes Bcl-2 apoptosis regulator, BCL2 associated X apoptosis regulator and cleaved caspase3, subsequently inducing apoptosis in MDA-MB-231 and MCF-7 breast cancer cells. These results indicated that dietary flavone may potentiate breast cancer cell apoptosis induced by metformin, and PI3K/AKT is involved in regulating MDMX/p53 signaling. This data suggests that dietary supplementary of flavone is a promising strategy for metformin mediated anticancer effects.

Autophagy inhibitor regulates apoptosis and proliferation of synovial fibroblasts through the inhibition of PI3K/AKT pathway in collagen-induced arthritis rat model

BACKGROUND AND OBJECTIVE

Mounting studies have illustrated an important role of autophagy in various diseases, but few studies have reported its contribution to rheumatoid arthritis (RA) and the underlying mechanism was largely unknown. This study aimed to investigate whether autophagy inhibitors could regulate apoptosis and proliferation through PI3K/AKT pathway in RA.

METHODS

RA animal model was established by collagen induction. General observations and degree of joint swelling were observed. Inflammatory response, cell survival related factors and apoptosis were also detected in synovial fibroblasts. In addition, cultured rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS) were subjected to TNF-α treatment in vitro, and TNF-α induced cell autophagy, synovial cell proliferation and apoptosis were detected. Moreover, cell cycle and cytokine secretion protein, along with the above parameters, were analyzed.

RESULTS

Results from the animal model showed that autophagy inhibitors attenuated inflammatory reaction and synovial hyperplasia, while promoted synovial fibroblasts apoptosis. Meanwhile, inhibition of autophagy promoted cell apoptosis and reversed cell proliferation in vitro, also blocked cell in the G2/M arrest and reduced the S phase cells. Furthermore, we observed that inhibition of PI3K/AKT pathway reversed TNF-α mediated autophagy and cytokine secretion.

CONCLUSION

autophagy inhibitors could mitigate inflammation response, inhibiting RA-FLS cell proliferation while promoting cell apoptosis by the PI3K/AKT pathway.

Inhibitory effect of Ginkgol C17:1 on the biological behavior of tumor cells

Ginkgol C17:1 is a bioactive compound derived from Ginkgo biloba. In the present study, the effect and possible mechanisms of action of Ginkgol C17:1 on the biological behaviors of tumor cells were investigated. Whilst cell proliferation was assessed using the MTT assay, the behaviors of cell migration and invasion were explored using Transwell and modified Transwell assays. The results revealed that Ginkgol C17:1 significantly inhibited the proliferation, migration and invasion of human tumor cells in a dose-dependent manner. Furthermore, due to their associations with the biological behaviors of tumor cells, the protein expression of matrix metalloproteinase (MMP)-7, Ras homolog gene family, member A (RhoA) and phosphorylated-protein kinase B (Akt) was analyzed by western blotting. The results showed that the expression of the aforementioned proteins was decreased markedly following Ginkgol C17:1 treatment. The results of the present study suggested that Ginkgol C17:1 suppresses the biological behaviors of tumor cells by inhibiting the activation of the mitogen-activated protein kinase/MMP, Rho/Rho-associated protein kinase and phosphatidylinositol 3-kinase/Akt signaling pathways.

The effect and mechanism of action of metformin on in vitro FaDu cell proliferation

Objective

To investigate the effect and mechanism of action of metformin on proliferation of a human hypopharyngeal carcinoma cell line (FaDu).

Methods

FaDu cells were treated with metformin (25–125 mmol/l). Cell proliferation was evaluated via CCK-8 assay. Real-time quantitative reverse transcription–polymerase chain reaction was used to evaluate microRNA (miR)-21-5p and PDCD4 (programmed cell death 4) expression. PDCD4 protein was quantified by Western blot.

Results

Metformin significantly inhibited FaDu cell proliferation in a dose- (25–100 mmol/l) and time-dependent manner (12 h–36 h), significantly downregulated miR-21-5p, and upregulated PDCD4 mRNA and protein expression.

Conclusions

Metformin significantly inhibited FaDu cell proliferation, possibly via downregulation of miR-21-5p and upregulation of PDCD4.

In-vitro Optimization of Nanoparticle-Cell Labeling Protocols for In-vivo Cell Tracking Applications

Recent advances in theranostic nanomedicine can promote stem cell and immune cell-based therapy. Gold nanoparticles (GNPs) have been shown to be promising agents for in-vivo cell-tracking in cell-based therapy applications. Yet a crucial challenge is to develop a reliable protocol for cell upload with, on the one hand, sufficient nanoparticles to achieve maximum visibility of cells, while on the other hand, assuring minimal effect of particles on cell function and viability. Previous studies have demonstrated that the physicochemical parameters of GNPs have a critical impact on their efficient uptake by cells. In the current study we have examined possible variations in GNP uptake, resulting from different incubation period and concentrations in different cell-lines. We have found that GNPs effectively labeled three different cell-lines - stem, immune and cancer cells, with minimal impairment to cell viability and functionality. We further found that uptake efficiency of GNPs into cells stabilized after a short period of time, while GNP concentration had a significant impact on cellular uptake, revealing cell-dependent differences. Our results suggest that while heeding the slight variations within cell lines, modifying the loading time and concentration of GNPs, can promote cell visibility in various nanoparticle-dependent in-vivo cell tracking and imaging applications.

Metformin synergistically sensitizes FLT3-ITD-positive acute myeloid leukemia to sorafenib by promoting mTOR-mediated apoptosis and autophagy

Mutations of Fms-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD), accounting for approximately 30% of patients with acute myeloid leukemia (AML), results in poor therapeutic efficacy and short survival. Sorafenib, an oral multikinase inhibitor, can inhibit FLT3 and improve clinical outcome of FLT3 mutated leukemia. Our current studies have shown that, the antidiabetic drug metformin also exerts anti-leukemic effect by activating p-AMPK and synergistically sensitizes FLT3 mutated AML to sorafenib. Both agents suppress cell proliferation in a dose-dependent manner and induce apoptosis via cell cycle arrest, but does not obviously modulate autophagy marker, light chain 3 (LC3). Mechanistically, in the presence of metformin, the anticancer potential of sorafenib, accompanying with increased LC3 levels, is found to be synergistically enhanced with the remarkably reduced protein expression of the mTOR/p70S6K/4EBP1 pathway, while not appreciably altering cell cycle. Overall, these results show metformin in aid of sorafenib may represent a promising and attractive strategy for the treatment of FLT3-ITD mutated AML.