Metformin inhibits the invasion of human hepatocellular carcinoma cells and enhances the chemosensitivity to sorafenib through a downregulation of the ERK/JNK-mediated NF-κB-dependent pathway that reduces uPA and MMP-9 expression

Modulatory effect of metformin and its transporters on immune infiltration in tumor microenvironment: a bioinformatic study with experimental validation

Metformin is a traditional antidiabetic drug for type 2 diabetes mellitus. However, it showed antitumor activity in many types of tumors, and it also has an influence on tumor metastasis in several types of tumors. It is transported through organic cationic transporters (OCTs), OCT1, OCT2, and OCT3, into the cells or into tumor microenvironment (TME). The complex interaction of metformin and its transporters on immune infiltration in TME of different types of tumors of The Cancer Genomic Atlas (TCGA) is not yet studied. The objective of this study is to identify the most suitable therapeutic target of tumors and immune infiltrates for metformin and its transporters in the TME. TIMER2.0, a bioinformatic tool, and other computational analysis were used to investigate this complex interaction; moreover, the identification of metformin target protein in TME is also investigated. The results revealed that the most suitable therapeutic target for metformin and OCTs among 32 types of TCGA data tumor types is Breast Invasive carcinoma (BRCA), and the most relevant immune infiltrate among 14 types of immune infiltrates that yields better prognosis and better therapeutical effect in TME is Macrophage M1. Furthermore, metformin showed a cytotoxic effect and an inhibitory effect on Urokinase Plasminogen Activator (uPA) gene expression in a concentration dependent fashion in MDA-MB-231 breast cancer cell line. This may suggest that metformin is a promising antitumor drug, stimulant for natural antitumor immune infiltrates, and inhibitor for metastasis in breast cancer.

Investigating the effect of metformin on chemobrain: Reports from cells to bedside

Chemobrain can be defined as the development of cognitive side effects following chemotherapy, which is increasingly reported in cancer survivor patients. Chemobrain leads to reduced patients' quality of life by causing different symptoms ranging from strokes and seizures to memory loss and mood disorders. Metformin, an antidiabetic drug, has been proposed as a potential treatment to improve the symptoms of chemotherapy-induced cognitive dysfunction. Several benefits of metformin on chemobrain have been suggested, including anti-inflammation, anti-oxidative stress, restoring impaired mitochondrial function, stabilizing apoptosis, ameliorating impairments to dendritic spine density, normalizing brain senescence protein levels, and attenuating reductions in cell viability, along with reversing learning and memory deficits. These benefits occur through various pathways of metformin, including adenosine monophosphate-activated protein kinase (AMPK), TAp73, and phosphatidylinositol 3-kinase/protein kinase B (Akt) pathways. In addition, metformin can exert neuroprotective effects and restore deficits in brain homeostasis caused by chemotherapy. Furthermore, activation of AMPK following metformin therapy promotes autophagy, stimulates energy production, and improves cell survival. Metformin's interaction with Tap73 and Akt pathways allows for regulated cell proliferation in adult neural precursor cells and cell growth, respectively. Although the negative effects on cerebral function induced by chemotherapeutics have been alleviated by metformin in several instances, further studies are required to confirm its beneficial effects. This research is essential as it addresses the pressing issue of chemobrain, which is on the rise alongside global increases in cancer. Exploring metformin's potential as a neuroprotective agent offers a promising avenue for mitigating these cognitive impairments and highlights the need for further studies to validate its therapeutic mechanisms. This review comprehensively summarises evidence from both in vitro and in vivo studies to demonstrate metformin's effects on cognitive function when co-administered with chemotherapy and identifies gaps in knowledge for further investigation.

Effects of Metformin on JNK Signaling Pathway and PD-L1 Expression in Triple Negative Breast Cancer

Background

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer. Metformin has been shown to have the potential to inhibit the proliferation of malignant cells. This study aimed to investigate the regulatory effect of metformin on the expression of programmed death protein ligand 1(PD-L1) and mechanisms in TNBC.

Methods

Mouse breast cancer cell line 4T1 was co-cultured with metformin, and the effect of metformin on cell proliferation was detected by MTT assay. The effect of metformin on the expression of JNK, RSK2 and CREB was detected by MAPK pathway protein chip. BALB/c mice were inoculated with 4T1 cells with knockdown/overexpression of C-Jun N-terminal kinase (JNK), and administered with metformin. The weight of tumor tissue was observed at the end of the experiment. The expression of PD-L1 in tumor cells was observed by immunofluorescence staining and the level of INF-γwas quantitatively determined by ELISA.

Results

Metformin inhibited the viability of 4T1 cells and increased the phosphorylation of JNK to reduce the phosphorylation of RSK2 and CREB. Metformin and JNK knockdown reduced the expression of PD-L1 in tumor cells, but there was no significant difference in the weight of tumor tissue. Metformin can reduce the level of INF-γ in tumor tissues, but JNK has no effect.

Conclusion

Metformin can inhibit the expression of PD-L1 in triple-negative breast cancer mice and improve the tumor microenvironment, but does not reduce the size of the tumor.

Mechanistic Insights about Sorafenib-, Valproic Acid- and Metformin-Induced Cell Death in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is among the main causes of death by cancer worldwide, representing about 80-90% of all liver cancers. Treatments available for advanced HCC include atezolizumab, bevacizumab, sorafenib, among others. Atezolizumab and bevacizumab are immunological options recently incorporated into first-line treatments, along with sorafenib, for which great treatment achievements have been reached. However, sorafenib resistance is developed in most patients, and therapeutical combinations targeting cancer hallmark mechanisms and intracellular signaling have been proposed. In this review, we compiled evidence of the mechanisms of cell death caused by sorafenib administered alone or in combination with valproic acid and metformin and discussed them from a molecular perspective.

The development and benefits of metformin in various diseases

Metformin has been used for the treatment of type II diabetes mellitus for decades due to its safety, low cost, and outstanding hypoglycemic effect clinically. The mechanisms underlying these benefits are complex and still not fully understood. Inhibition of mitochondrial respiratory-chain complex I is the most described downstream mechanism of metformin, leading to reduced ATP production and activation of AMP-activated protein kinase (AMPK). Meanwhile, many novel targets of metformin have been gradually discovered. In recent years, multiple pre-clinical and clinical studies are committed to extend the indications of metformin in addition to diabetes. Herein, we summarized the benefits of metformin in four types of diseases, including metabolic associated diseases, cancer, aging and age-related diseases, neurological disorders. We comprehensively discussed the pharmacokinetic properties and the mechanisms of action, treatment strategies, the clinical application, the potential risk of metformin in various diseases. This review provides a brief summary of the benefits and concerns of metformin, aiming to interest scientists to consider and explore the common and specific mechanisms and guiding for the further research. Although there have been countless studies of metformin, longitudinal research in each field is still much warranted.

Animal Models of Hepatocellular Carcinoma: Current Applications in Clinical Research

In the last decade, relevant advances have occurred in the treatment of hepatocellular carcinoma (HCC), with novel drugs entering the clinical practice, among which tyrosine kinase inhibitors (TKIs) such as lenvatinib, cabozantinib and regorafenib, and immune checkpoint inhibitors (ICPIs) either alone or in combination with VEGF inhibitors. Clinical trials have driven the introduction of such novel molecules into the clinics but, at present, no biomarker drives the choice of first-line options, which relies only upon clinical and imaging assessment. Remarkably, clinical and imaging-based evaluations do not consider the huge heterogeneity of HCC and do not allow to realize the potential of personalized treatments. Preclinical research still does not inform the design of clinical trials, even though many animal models mimicking specific subgroups of HCC are available and might provide relevant information. Although animal models directly informing the clinical practice, such as patients-derived xenografts, are not used to help the choice of treatment in advanced HCC, however, the preclinical research can count on a wide range of valuable models. Here we will review some HCC models which might turn informative for specific questions in defined patient subgroups, and we will describe recent preclinical studies for the mechanistic evaluation of immunotherapy-based treatment approaches. To this aim, we will mainly focus on two issues: (i) HCC models informative on NAFLD-NASH HCC and (ii) HCC models helping to elucidate mechanisms underneath immunotherapy. We have chosen these two settings since they represent, respectively, the most rapidly arising cause of chronic liver disease (CLD) and HCC in western countries and the most promising therapeutic option for advanced HCC.

Metformin Inducing the Change of Functional and Exhausted Phenotypic Tumor-Infiltrated Lymphocytes and the Correlation with JNK Signal Pathway in Triple-Negative Breast Cancer

BACKGROUND

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer. Metformin has been shown to have the potential to inhibit the proliferation of malignant cells. This study aimed to investigate the regulatory effect of metformin on phenotypic tumor-infiltrated lymphocytes (TILs) and mechanisms in TNBC.

METHODS

Microarray analysis was performed on 4T1 cells post metformin treatment. BALB/c mice were inoculated with 4T1 cells with knockdown/overexpression of C-Jun N-terminal kinase (JNK), and administered with metformin. Phenotypic TILs in the tumor microenvironment (TME) were visualized by immunofluorescence staining.

RESULTS

Metformin inhibited 4T1 cell proliferation and increased expression of JNK by 21% in vitro. In vivo, Metformin increased cell counts of CD4+ and CD8+TILs by 100% and 85%, respectively, and the increase of TILs was associated with JNK pathway. Cell counts of CD4+/PD-1+ and CD8+/PD-1+TILs were reduced by 64% and 58%, respectively, post metformin treatment, but the reduction of exhausted TILs was not associated with JNK pathway. Metformin induced a 11% and 20% reduction of IL-6 and TNF-α level in the TNBC model.

CONCLUSION

Our study demonstrated that metformin increased the functional phenotype of TILs and associated with JNK pathway, and suppressed the exhausted phenotype of TILs independently to JNK pathway in TNBC microenvironment. Further studies are needed to explore the basic mechanism of action of the drug. Metformin has potentially enhanced efficacy when used in combination with immunotherapy against TNBC.

Metformin Enhances the Anti-Cancer Efficacy of Sorafenib via Suppressing MAPK/ERK/Stat3 Axis in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) incidence, as well as related mortality, has been steadily increasing in the USA and across the globe, partly due to the lack of effective therapeutic options for advanced HCC. Though sorafenib is considered standard-of-care for advanced HCC, it only improves median survival by a few months when compared to placebo. Sorafenib is also associated with several unpleasant side effects that often lead to early abatement of therapy. Here, we investigate whether a combination regimen including low-dose sorafenib and a non-toxic dose of anti-diabetic drug metformin can achieve effective inhibition of HCC. Indeed, combining metformin with low-dose sorafenib inhibited growth, proliferation, migration, and invasion potential of HCC cells. We observed a 5.3- and 1.9-fold increase in sub-G1 population in the combination treatment compared to sorafenib alone. We found that the combination of metformin enhanced the efficacy of sorafenib and inhibited the MAPK/ERK/Stat3 axis. Our in vivo studies corroborated the in vitro findings, and mice harboring HepG2-derived tumors showed effective tumor reduction upon treatment with low-dose sorafenib and metformin combination. This work sheds light on a therapeutic strategy aiming to augment sorafenib efficacy or dose-de-escalation that may prove beneficial in circumventing sorafenib resistance as well as minimizing related side effects.

Metformin inhibits the development and metastasis of colorectal cancer

Metformin is a commonly used drug for the treatment of diabetes. Accumulating evidence suggests that it exerts anti-cancer effects in many cancers, including colorectal cancer. However, the underlying molecular mechanisms of colorectal cancer metastasis remain unclear. Colorectal cancer cell lines were treated with metformin, and cell proliferation, invasion, and migration were analyzed in vitro. The relationship between metformin and the AMPK-mTOR axis was assessed by Western blot analysis and transfection with small interfering RNA. A colorectal cancer xenograft mouse model was used to observe the effects of metformin on liver metastasis. Immunohistochemical analysis was performed on liver metastatic tumors. In in vitro experiments, metformin significantly inhibited the proliferation, migration, and invasion only in HCT116 and SW837 cells, but not in HCT8 and Lovo cells. Only in HCT116 and SW837, a change in AMPK-mTOR expression was observed in a dose-dependent manner. In colorectal cancer xenograft mice, the liver metastatic rate (10% vs. 50%, p = 0.05) and the number of liver metastatic nodules (0.1/body vs. 1.2/body, p = 0.04) were significantly lower in the metformin group. Tumor proliferation and EMT were decreased and apoptosis was promoted only in metastatic liver tumors of mice treated with metformin. The molecular mechanism of the anti-cancer effects of metformin involves repression of mTOR pathways via AMPK activation. Moreover, the differences in metformin sensitivity depend on the response of the AMPK-mTOR pathway to metformin. Our study provides a theoretical basis for the anti-metastatic treatment of colorectal cancer using metformin.

CAF-derived exosomes transmitted Gremlin-1 promotes cancer progression and decreases the sensitivity of hepatoma cells to sorafenib

Hepatocellular carcinoma (HCC) is one of the most lethal malignancies worldwide because of metastasis. An increasing number of studies have reported that cancer-associated fibroblasts (CAFs) have emerged as the largest component of the stroma and play a critical role in tumor-promoting processes. However, the effects of CAFs on cancer progression and the sensitivity of hepatoma cells to sorafenib are not well characterized. Here, we identified the proteome of CAF-derived exosomes, and unveiled that exosomal Gremlin-1 derived from CAFs contributes to epithelial-mesenchymal transition (EMT) of hepatoma cells and the decrease of the sorafenib sensitivity through regulating Wnt/β-catenin and BMP signaling pathways. Compared to control subjects, the level of plasma exosomal Gremlin-1 was significantly increased in HCC patients. Further studies indicated that plasma exosomal Gremlin-1 may predict sorafenib response in HCC patients. Collectively, our findings uncover CAFs-derived Gremlin-1-rich exosomes promote EMT and decrease the sensitivity of hepatoma cells to sorafenib by Wnt/β-catenin and BMP signaling.

Resveratrol Decreases the Invasion Potential of Gastric Cancer Cells

The cancer-preventive agent Resveratrol (RSV) [3,5,4′-trihydroxytrans-stilbene] is a widely recognized antioxidant molecule with antitumoral potential against several types of cancers, including prostate, hepatic, breast, skin, colorectal, and pancreatic. Herein, we studied the effect of RSV on the cell viability and invasion potential of gastric cancer cells. AGS and MKN45 cells were treated with different doses of RSV (0–200 μM) for 24 h. Cell viability was determined using the Sulphorhodamine B dye (SRB) assay. For invasion assays, gastric cells were pre-treated with RSV (5–25 μM) for 24 h and then seeded in a Transwell chamber with coating Matrigel. The results obtained showed that RSV inhibited invasion potential in both cell lines. Moreover, to elucidate the mechanism implicated in this process, we analyzed the effects of RSV on SOD, heparanase, and NF-κB transcriptional activity. The results indicated that RSV increased SOD activity in a dose-dependent manner. Conversely, RSV significantly reduced the DNA-binding activity of NF-κB and the enzymatic activity of heparanase in similar conditions, which was determined using ELISA-like assays. In summary, these results show that RSV increases SOD activity but decreases NF-kB transcriptional activity and heparanase enzymatic activity, which correlates with the attenuation of invasion potential in gastric cancer cells. To our knowledge, no previous study has described the effect of RSV on heparanase activity. This article proposes that heparanase could be a key effector in the invasive events occurring during gastric cancer metastasis.

Matrix Metalloproteinases in Chemoresistance: Regulatory Roles, Molecular Interactions, and Potential Inhibitors

Cancer is one of the major causes of death worldwide. Its treatments usually fail when the tumor has become malignant and metastasized. Metastasis is a key source of cancer recurrence, which often leads to resistance towards chemotherapeutic agents. Hence, most cancer-related deaths are linked to the occurrence of chemoresistance. Although chemoresistance can emerge through a multitude of mechanisms, chemoresistance and metastasis share a similar pathway, which is an epithelial-to-mesenchymal transition (EMT). Matrix metalloproteinases (MMPs), a class of zinc and calcium-chelated enzymes, are found to be key players in driving cancer migration and metastasis through EMT induction. The aim of this review is to discuss the regulatory roles and associated molecular mechanisms of specific MMPs in regulating chemoresistance, particularly EMT initiation and resistance to apoptosis. A brief presentation on their potential diagnostic and prognostic values was also deciphered. It also aimed to describe existing MMP inhibitors and the potential of utilizing other strategies to inhibit MMPs to reduce chemoresistance, such as upstream inhibition of MMP expressions and MMP-responsive nanomaterials to deliver drugs as well as epigenetic regulations. Hence, manipulation of MMP expression can be a powerful tool to aid in treating patients with chemo-resistant cancers. However, much still needs to be done to bring the solution from bench to bedside.

Transcriptome Analysis of Liver Cancer Cell Huh-7 Treated With Metformin

Metformin is a kind of widely used antidiabetic drug that regulates glucose homeostasis by inhibiting liver glucose production and increasing muscle glucose uptake. Recently, some studies showed that metformin exhibits anticancer properties in a variety of cancers. Although several antitumor mechanisms have been proposed for metformin action, its mode of action in human liver cancer remains not elucidated. In our study, we investigated the underlying molecular mechanisms of metformin's antitumor effect on Huh-7 cells of hepatocellular carcinoma (HCC) in vitro. RNA sequencing was performed to explore the effect of metformin on the transcriptome of Huh-7 cells. The results revealed that 4,518 genes (with log2 fold change > 1 or < −1, adjusted p-value < 0.05) were differentially expressed in Huh-7 cells with treatment of 25-mM metformin compared with 0-mM metformin, including 1,812 upregulated and 2,706 downregulated genes. Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses identified 54 classical pathways that were significantly enriched, and 16 pathways are closely associated with cancer, such as cell cycle, DNA replication, extracellular matrix–receptor interaction, and so on. We selected 11 differentially expressed genes, which are closely associated with HCC, to validate their differential expressions through a quantitative real-time reverse transcription-polymerase chain reaction. The result exhibited that the genes of fatty acid synthase, mini-chromosome maintenance complex components 6 and 5, myristoylated alanine-rich C-kinase substrate, fatty acid desaturase 2, C-X-C motif chemokine ligand 1, bone morphogenetic protein 4, S-phase kinase-associated protein 2, kininogen 1, and proliferating cell nuclear antigen were downregulated, and Dual-specificity phosphatase-1 is significantly upregulated in Huh-7 cells with treatment of 25-mM metformin. These differentially expressed genes and pathways might play a crucial part in the antitumor effect of metformin and might be potential targets of metformin treating HCC. Further investigations are required to evaluate the metformin mechanisms of anticancer action in vivo.

SPINKs in Tumors: Potential Therapeutic Targets

The serine protease inhibitor Kazal type (SPINK) family includes SPINK1-14 and is the largest branch in the serine protease inhibitor family. SPINKs play an important role in pancreatic physiology and disease, sperm maturation and capacitation, Nager syndrome, inflammation and the skin barrier. Evidence shows that the unregulated expression of SPINK1, 2, 4, 5, 6, 7, and 13 is closely related to human tumors. Different SPINKs exhibit various regulatory modes in different tumors and can be used as tumor prognostic markers. This article reviews the role of SPINK1, 2, 4, 5, 6, 7, and 13 in different human cancer processes and helps to identify new cancer treatment targets.

Melatonin combined with sorafenib synergistically inhibit the invasive ability through targeting metastasis-associated protein 2 expression in human renal cancer cells

Objectives:

Materials and Methods:

Results:

Conclusion:

Compound Danshen Dripping Pill inhibits high altitude-induced hypoxic damage by suppressing oxidative stress and inflammatory responses

CONTEXT

Previous studies indicate that compound Danshen Dripping Pill (CDDP) improves the adaptation to high-altitude exposure. However, its mechanism of action is not clear.

OBJECTIVE

To explore the protective effect of CDDP on hypobaric hypoxia (HH) and its possible mechanism.

MATERIALS AND METHODS

A meta-analysis of 1051 human volunteers was performed to evaluate the effectiveness of CDDP at high altitudes. Male Sprague-Dawley rats were randomized into 5 groups (n = 6): control at normal pressure, model, CDDP-170 mg/kg, CDDP-340 mg/kg and acetazolamide groups. HH was simulated at an altitude of 5500 m for 24 h. Animal blood was collected for arterial blood-gas analysis and cytokines detection and their organs were harvested for pathological examination. Expression levels of AQP1, NF-κB and Nrf2 were determined by immunohistochemical staining.

RESULTS

The meta-analysis data indicated that the ratio between the combined RR of the total effective rate and the 95% CI was 0.23 (0.06, 0.91), the SMD and 95% CI of SO₂ was 0.37 (0.12, 0.62). Pre-treatment of CDDP protected rats from HH-induced pulmonary edoema and heart injury, left-shifted oxygen-dissociation curve and decreased P50 (30.25 ± 3.72 vs. 37.23 ± 4.30). Mechanistically, CDDP alleviated HH-reinforced ROS by improving SOD and GPX1 while inhibiting pro-inflammatory cytokines and NF-κB expression. CDDP also decreased HH-evoked D-dimer, erythrocyte aggregation and blood hemorheology, promoting AQP1 and Nrf2 expression.

DISCUSSION AND CONCLUSIONS

Pre-treatment with CDDP could prevent HH-induced tissue damage, oxidative stress and inflammatory response. Suppressed NF-κB and up-regulated Nrf2 might play significant roles in the mechanism of CDDP.

Anti-angiogenesis and anti-metastasis effects of Polyphyllin VII on Hepatocellular carcinoma cells in vitro and in vivo

Background

Polyphyllin VII (PP7), a steroidal saponin from P. polyphylla has been found to exert strong anticancer activity. Little is known about the anti-angiogenesis and anti-metastasis properties of PP7. In this study, the anti-angiogenic and anti-metastatic effects of PP7 on HCC and the molecular mechanisms were evaluated.

Methods

Effect of PP7 on angiogenesis was assessed by tube formation assay and applied a transgenic Tg(fli1:EGFP) zebrafish model. Effects of PP7 on tumor metastasis and invasion were examined in cell migration and invasion assay, zebrafish tumor xenograft models and lung metastasis mouse models. The protein levels were examined by Western blotting.

Results

PP7 significantly decreased the tube formation of human umbilical vein endothelial cells, the number and length of ISVs and SIVs of transgenic zebrafish, and the metastasis and invasion of cancer cells in vitro and in vivo. The anti-angiogenic and anti-metastatic effects of PP7 in HepG2 cells were attributable, at least partially, to downregulated NF-κB/MMP-9/VEGF signaling pathway.

Conclusion

This study demonstrates that PP7 possesses strong anti-angiogenesis and anti-metastasis activities, suggesting that PP7 could be a potential candidate agent for HCC treatment.

Metformin enhances the cytotoxic effect of nilotinib and overcomes nilotinib resistance in chronic myeloid leukemia cells

BACKGROUND/AIMS

Nilotinib is used for treating patients with imatinib-sensitive or -resistant chronic myeloid leukemia (CML); however, nilotinib-resistant cases have been observed in recent years. In addition, a considerable number of patients receiving nilotinib developed diabetes. Metformin is a front-line drug for the treatment of type 2 diabetes, and several studies have shown that diabetes patients treated with metformin have reduced incidence of cancer. This study aimed to define the effect of metformin on CML cells to determine whether metformin overcomes nilotinib resistance, and to identify novel targets for the treatment of nilotinib resistance.

METHODS

We observed the effects of metformin and nilotinib on K562 and KU812 human CML cell lines. Nilotinib-resistant CML cell lines were generated by exposing cells to gradually increasing doses of nilotinib. Then, we investigated the driving force that makes resistance to nilotinib and the effect of metformin on the driving force.

RESULTS

Sub-toxic doses of metformin enhanced nilotinib efficacy by reducing Bcl-xL expression, which induces apoptosis in CML cells. Next, we generated nilotinib-resistant K562 and KU812 cell lines that overexpressed the c-Jun N-terminal kinase (JNK) gene. JNK silencing by a JNK inhibitor restored sensitivity to nilotinib. Furthermore, metformin was effective in decreasing phosphorylated JNK levels, restoring nilotinib sensitivity. Combined treatment with nilotinib and metformin was more effective than combined treatment with nilotinib and a JNK inhibitor in terms of cell proliferation inhibition.

CONCLUSION

This study suggested that combination therapy with metformin and nilotinib may have clinical benefits of enhancing antileukemia efficacy and overcoming resistance to nilotinib.

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.>.

A Systematic Review of the Pharmacology, Toxicology and Pharmacokinetics of Matrine

Matrine (MT) is a naturally occurring alkaloid and an bioactive component of Chinese herbs, such as Sophora flavescens and Radix Sophorae tonkinensis. Emerging evidence suggests that MT possesses anti-cancer, anti-inflammatory, anti-oxidant, antiviral, antimicrobial, anti-fibrotic, anti-allergic, antinociceptive, hepatoprotective, cardioprotective, and neuroprotective properties. These pharmacological properties form the foundation for its application in the treatment of various diseases, such as multiple types of cancers, hepatitis, skin diseases, allergic asthma, diabetic cardiomyopathy, pain, Alzheimer's disease (AD), Parkinson's disease (PD), and central nervous system (CNS) inflammation. However, an increasing number of published studies indicate that MT has serious adverse effects, the most obvious being liver toxicity and neurotoxicity, which are major factors limiting its clinical use. Pharmacokinetic studies have shown that MT has low oral bioavailability and short half-life in vivo. This review summarizes the latest advances in research on the pharmacology, toxicology, and pharmacokinetics of MT, with a focus on its biological properties and mechanism of action. The review provides insight into the future of research on traditional Chinese medicine.

Metformin Inhibited Proliferation and Metastasis of Colorectal Cancer and presented a Synergistic Effect on 5-FU

The purpose of this study was to investigate the effect of metformin or the combination of metformin and 5-FU on the growth and metastasis of colorectal cancer (CRC). For the in vitro experiments, HCT 116 and SW1463 cell lines were treated with metformin or the combination of metformin and 5-FU. Cell proliferation and invasion were analyzed by CCK-8, colony formation, and transwell assay, respectively. For the in vivo experiments, the CRC xenograft nude mice model was used to observe the effects of metformin or combined with 5-FU on tumor growth and metastasis. Metformin significantly inhibited the proliferation and invasion of HCT116 and SW1463 cells in vitro, which showed synergetic effects to 5-FU. In CRC xenograft nude mice, metformin alone and metformin combined with 5-FU treatment significantly inhibited tumor cell proliferation and tumor metastasis. In summary, metformin played an inhibitory role in the proliferation and metastasis of CRC and had a synergistic effect with 5-FU. Metformin may be a potentially effective anti-metastatic drug or an anticancer adjuvant agent for treating CRC.

Tetrahydrocurcumin mitigates acute hypobaric hypoxia-induced cerebral oedema and inflammation through the NF-κB/VEGF/MMP-9 pathway

High-altitude cerebral oedema (HACE) is a potentially fatal manifestation of high-altitude sickness and is caused partly by inflammation and the blood-brain barrier disruption. Tetrahydrocurcumin (THC) has been reported to exert effective antioxidative and anti-inflammatory effects; This study sought to elucidate the underlying mechanism of THC in mitigating HACE using a mouse model. Our results revealed that prophylactic administration of THC (40 mg/kg) for 3 days significantly alleviated the increase in brain water content (BWC), interleukin-1β (IL-1β) and TNF-α levels caused by acute hypobaric hypoxia (AHH). Additionally, superoxide dismutase (SOD) activity was increased by THC to enhance the ability to resist hypoxia. Histological and ultrastructural analysis of the cerebrum revealed that THC administration mitigated AHH-induced pericellular oedema and reduced the perivascular space, resulting in the simultaneous remission of oedema and protection of mitochondria in the cerebrum. In vitro, astrocytes exposed to hypoxia (4% O₂ ) for 24 hr exhibited and increase in IL-1β expression followed by an increase in vascular endothelial growth factor (VEGF) levels. Furthermore, THC administration remarkably downregulated VEGF, matrix metallopeptidase-9 (MMP-9), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) expression, both in vivo and in vitro. Our data highlight the potential prophylactic activity of THC in HACE, it effectively mitigates AHH-induced cerebral oedema and inflammation is associated with the inhibition of the NF-κB/ VEGF/MMP-9 pathways.

Thrombospondin-1: A Key Protein That Induces Fibrosis in Diabetic Complications

Fibrosis accompanies most common pathophysiological features of diabetes complications in different organs. It is characterized by an excessive accumulation of extracellular matrix (ECM) components, the response to which contributes to inevitable organ injury. The extracellular protein thrombospondin-1 (TSP-1), a kind of extracellular glycoprotein, is upregulated by the increased activity of some transcription factors and results in fibrosis by activating multiple pathways in diabetes. The results of studies from our team and other colleagues indicate that TSP-1 is associated with the pathological process leading to diabetic complications and is considered to be the most important factor in fibrosis. This review summarizes the molecular mechanism of increased TSP-1 induced by hyperglycemia and the role of TSP-1 in fibrosis during the development of diabetes complications.

Context-Dependent Role of NF-κB Signaling in Primary Liver Cancer-from Tumor Development to Therapeutic Implications

Chronic inflammatory cell death is a major risk factor for the development of diverse cancers including liver cancer. Herein, disruption of the hepatic microenvironment as well as the immune cell composition are major determinants of malignant transformation and progression in hepatocellular carcinomas (HCC). Considerable research efforts have focused on the identification of predisposing factors that promote induction of an oncogenic field effect within the inflammatory liver microenvironment. Among the most prominent factors involved in this so-called inflammation-fibrosis-cancer axis is the NF-κB pathway. The dominant role of this pathway for malignant transformation and progression in HCC is well documented. Pathway activation is significantly linked to poor prognostic traits as well as stemness characteristics, which places modulation of NF-κB signaling in the focus of therapeutic interventions. However, it is well recognized that the mechanistic importance of the pathway for HCC is highly context and cell type dependent. While constitutive pathway activation in an inflammatory etiological background can significantly promote HCC development and progression, absence of NF-κB signaling in differentiated liver cells also significantly enhances liver cancer development. Thus, therapeutic targeting of NF-κB as well as associated family members may not only exert beneficial effects but also negatively impact viability of healthy hepatocytes and/or cholangiocytes, respectively. The review presented here aims to decipher the complexity and paradoxical functions of NF-κB signaling in primary liver and non-parenchymal cells, as well as the induced molecular alterations that drive HCC development and progression with a particular focus on (immune-) therapeutic interventions.

Metformin promotes survivin degradation through AMPK/PKA/GSK-3β-axis in non-small cell lung cancer

Metformin, a first-line antidiabetic drug, has been reported with anticancer activities in many types of cancer. However, its molecular mechanisms remain largely unknown. As a member of inhibitor of apoptosis proteins, survivin plays an important role in the regulation of cell death. In the present study, we investigated the role of survivin in metformin-induced anticancer activity in non-small cell lung cancer in vitro. Metformin mainly induced apoptotic cell death in A549 and H460 cell lines. It remarkably suppressed the expression of survivin, decreased the stability of this protein, then promoted its proteasomal degradation. Moreover, metformin greatly suppressed protein kinase A (PKA) activity and induced its downstream glycogen synthase kinase 3β (GSK-3β) activation. PKA activators, both 8-Br-cAMP and forskolin, significantly increased the expression of survivin. Consistently both GSK-3β inhibitor LiCl and siRNA restored the expression of survivin in lung cancer cells. Furthermore, metformin induced adenosine 5'-monophosphate-activated protein kinase (AMPK) activation. Suppression of the activity of AMPK with Compound C reversed the degradation of survivin induced by metformin, and meanwhile, restored the activity of PKA and GSK-3β. These results suggest that metformin kills lung cancer cells through AMPK/PKA/GSK-3β-axis-mediated survivin degradation, providing novel insights into the anticancer effects of metformin.

The Role of AMP-Activated Protein Kinase as a Potential Target of Treatment of Hepatocellular Carcinoma

Background: Hepatocellular carcinoma (HCC) is the fifth most frequent cancer worldwide with a very high recurrence rate and very dismal prognosis. Diagnosis and treatment in HCC remain difficult, and the identification of new therapeutic targets is necessary for a better outcome of HCC treatment. AMP-Activated Protein Kinase (AMPK) is an essential intracellular energy sensor that plays multiple roles in cellular physiology and the pathological development of chronic diseases. Recent studies have highlighted the important regulation of AMPK in HCC. This review aims to comprehensively and critically summarize the role of AMPK in HCC. Methods: Original studies were retrieved from NCBI database with keywords including AMPK and HCC, which were analyzed with extensive reading. Results: Dysregulation of the kinase activity and expression of AMPK was observed in HCC, which was correlated with survival of the patients. Loss of AMPK in HCC cells may proceed cell cycle progression, proliferation, survival, migration, and invasion through different oncogenic molecules and pathways. Conclusions: We identified several AMPK activators which may possess potential anti-HCC function, and discussed the clinical perspective on the use of AMPK activators for HCC therapy.

Metformin triggers the intrinsic apoptotic response in human AGS gastric adenocarcinoma cells by activating AMPK and suppressing mTOR/AKT signaling

Metformin is commonly used to treat patients with type 2 diabetes and is associated with a decreased risk of cancer. Previous studies have demonstrated that metformin can act alone or in synergy with certain anticancer agents to achieve anti-neoplastic effects on various types of tumors via adenosine monophosphate-activated protein kinase (AMPK) signaling. However, the role of metformin in AMPK-mediated apoptosis of human gastric cancer cells is poorly understood. In the current study, metformin exhibited a potent anti-proliferative effect and induced apoptotic characteristics in human AGS gastric adenocarcinoma cells, as demonstrated by MTT assay, morphological observation method, terminal deoxynucleotidyl transferase dUTP nick end labeling and caspase-3/7 assay kits. Western blot analysis demonstrated that treatment with metformin increased the phosphorylation of AMPK, and decreased the phosphorylation of AKT, mTOR and p70S6k. Compound C (an AMPK inhibitor) suppressed AMPK phosphorylation and significantly abrogated the effects of metformin on AGS cell viability. Metformin also reduced the phosphorylation of mitogen-activated protein kinases (ERK, JNK and p38). Additionally, metformin significantly increased the cellular ROS level and included loss of mitochondrial membrane potential (ΔΨm). Metformin altered apoptosis-associated signaling to downregulate the BAD phosphorylation and Bcl-2, pro-caspase-9, pro-caspase-3 and pro-caspase-7 expression, and to upregulate BAD, cytochrome c, and Apaf-1 proteins levels in AGS cells. Furthermore, z-VAD-fmk (a pan-caspase inhibitor) was used to assess mitochondria-mediated caspase-dependent apoptosis in metformin-treated AGS cells. The findings demonstrated that metformin induced AMPK-mediated apoptosis, making it appealing for development as a novel anticancer drug for the treating gastric cancer.

Metformin induces apoptotic cytotoxicity depending on AMPK/PKA/GSK-3β-mediated c-FLIPL degradation in non-small cell lung cancer

Background

Metformin, a first-line antidiabetic drug, has recently been reported with anticancer activities in various cancers; however, the underlying mechanisms remain elusive. The aim of the present study was to investigate the role of cellular FADD-like IL-1β-converting enzyme (FLICE)-inhibitory protein large (c-FLIP_L) in metformin-induced anticancer activity in non-small cell lung cancer (NSCLC) in vitro.

Materials and methods

Cell viability was measured by MTT assay. Quantitative real-time PCR was carried out to detect the level of mRNA of related genes. The expression of related proteins was detected by Western blot. siRNA was used to silence the expression of targeted proteins.

Results

Metformin significantly suppressed proliferation of both A549 and H460 cells in a dose-dependent manner. Mechanistic studies suggested that metformin killed NSCLC cells by inducing apoptotic cell death. Moreover, metformin greatly inhibited c-FLIP_L expression and then promoted its degradation. Furthermore, metformin significantly activated Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) and its downstream glycogen synthase kinase 3beta (GSK-3β), block the expression of AMPK, and GSK-3β with siRNA partially reversed metformin-induced cytotoxicity and restored the expression of c-FLIP_L in lung cancer cells. Metformin also suppressed the activity of AMPK downstream protein kinase A (PKA), PKA activators, both 8-Br-cAMP and forskolin, greatly increased c-FLIP_L expression in NSCLC cells.

Conclusion

This study provided evidence that metformin killed NSCLC cells through AMPK/PKA/GSK-3β axis-mediated c-FLIP_L degradation.

Metformin delays AKT/c-Met-driven hepatocarcinogenesis by regulating signaling pathways for de novo lipogenesis and ATP generation

Hepatocellular carcinoma (HCC) is a lethal malignancy with few effective options for therapeutic treatment in its advanced stages. Metformin, a first-line oral agent used in the treatment of type 2 diabetes, exhibits efficacy in metabolic reprogramming fueling changes in cell growth and proliferation for multiple cancer types, including HCC. However, the molecular mechanism by which metformin delays hepatocarcinogenesis in individuals with hepatic steatosis remains rare. Here, we investigate the preventive efficacy of metformin in a rapid AKT/c-Met-triggered HCC mouse model featuring excessive levels of steatosis. Hematoxylin and eosin staining, Oil Red O staining and immunoblotting were applied for mechanistic investigations. Pharmacological and biochemical strategies were employed to illuminate molecular evidence for HCC cell lines. The results show that metformin obstructs the malignant transformation of hepatocytes in AKT/c-Met mice. Mechanistically, metformin reduces the expression of phospho-ERK (Thr202/Tyr204) and two forms of proto-oncogenes, Cyclin D1 and c-Myc, in AKT/c-Met mice. Moreover, metformin ameliorates FASN-mediated aberrant lipogenesis and HK2/PKM2-driven ATP generation in vivo. Furthermore, metformin represses the expression of FASN and HK-2 by targeting c-Myc in an AMPK-dependent manner in vitro. In addition, metformin is effective at inhibiting PKM2 expression in the presence of an AMPK inhibitor compound C, suggesting that its functioning in PKM2 is AMPK-independent. Our study experimentally validates a novel molecular mechanism by which metformin alleviates enhanced lipogenesis and high energy metabolism during hepatocarcinogenesis, indicating that metformin may serve as an agent for the prevention of HCC in patients with nonalcoholic fatty liver diseases.

Synergistic antimetastatic effect of cotreatment with licochalcone A and sorafenib on human hepatocellular carcinoma cells through the inactivation of MKK4/JNK and uPA expression

To improve the clinical outcome of tumor chemotherapy, more effective combination treatments against tumor metastasis and recurrence are required. Licochalcone A (LicA) is the root of Glycyrrhiza inflata and has been reported to possess anti-inflammatory, antimicrobial, and antitumor effects. Sorafenib (Sor), a multikinase inhibitor, is used to treat patients with solid tumors such as advanced hepatocellular carcinoma (HCC). However, the synergistic effects of LicA and Sor on the metastasis of human HCC cells have not been reported. We found that LicA and Sor did not have cytotoxic effects or arrest growth in human SK-Hep-1 and Huh-7 cells. In addition, treatment with LicA or Sor alone inhibited migration and invasion in human SK-Hep-1 and Huh-7 HCC cells. Furthermore, cotreatment with LicA and Sor synergistically inhibited the migration and invasion of HCC cells and significantly inhibited uPA protein expression. Notably, cotreatment of LicA and Sor synergistically and significantly downregulated MKK4-JNK expression. Through tail vein injection in nude mice, the aforementioned cotreatment synergistically suppressed SK-Hep-1 cell-mediated lung metastasis. These findings first revealed the synergistic effects of LicA and Sor cotreatment against human HCC cells, further suggesting that beneficial effects on tumor regression could be confirmed through prospective clinical trials.

Novel application of metformin combined with targeted drugs on anticancer treatment

The success of targeted drug therapies for treating cancer patients has attracted broad attention both in the academic community and social society. However, rapidly developed acquired resistance is becoming a newly recognized major challenge to the continuing efficiency of these therapies. Metformin is a well‐known natural compound with low toxicity derived from the plant French lilac. Our previous work has highlighted research progress of the combination of clinically applied chemotherapies and metformin by different mechanisms. We have also launched a study to combine metformin with the small molecule targeted drug gefitinib to treat bladder cancer using intravesical administration. Thus, in this minireview, we summarize recent achievements combining metformin with various targeted therapies. This work directs the potential clinical future by selecting available cancer patients and providing precise medicine by the combination of metformin and targeted drugs to overcome resistance and enhance therapeutic efficacies.

Metformin and blood cancers

Type 2 diabetes mellitus and cancer are correlated with changes in insulin signaling, a pathway that is frequently upregulated in neoplastic tissue but impaired in tissues that are classically targeted by insulin in type 2 diabetes mellitus. Many antidiabetes treatments, particularly metformin, enhance insulin signaling, but this pathway can be inhibited by specific cancer treatments. The modulation of cancer growth by metformin and of insulin sensitivity by anticancer drugs is so common that this phenomenon is being studied in hundreds of clinical trials on cancer. Many meta-analyses have consistently shown a moderate but direct effect of body mass index on the incidence of multiple myeloma and lymphoma and the elevated risk of leukemia in adults. Moreover, new epidemiological and preclinical studies indicate metformin as a therapeutic agent in patients with leukemia, lymphomas, and multiple myeloma. In this article, we review current findings on the anticancer activities of metformin and the underlying mechanisms from preclinical and ongoing studies in hematologic malignancies.

Metformin induces miR-378 to downregulate the CDK1, leading to suppression of cell proliferation in hepatocellular carcinoma

Metformin is one of the extensively and most commonly used oral antihyperglycemic agents, but it has been shown to exert antineoplastic effects in many cancer cells. Recent studies have confirmed that metformin has an antitumor effect on hepatocellular carcinoma (HCC). However, the molecular mechanism underlying this effect needs to be further studied.

MATERIALS AND METHODS

CDK1 and miR-378 expression was analyzed by western blotting and real-time PCR assays. We confirmed the association between miR-378 and CDK1 by dual luciferase reporter assay. The role of the miR-378/CDK1 pathway in proliferation, cell cycle and apoptosis was examined in vitro. The effect of miR-378 on HCC tumor growth was evaluated in nude xenograft mouse model.

RESULTS

Our study found that metformin significantly inhibited the HCC cell proliferation via inducing G2/M arrest. At the same time, metformin efficiently decreased CDK1 expression and elevated miR-378 level. Moreover, the upregulation of miR-378 also repressed HCC cell proliferation by causing G2/M arrest and inhibited tumor growth. Additionally, we demonstrated that miR-378 directly targeted CDK1 3'UTR and downregulated CDK1 mRNA and protein levels. Furthermore, metformin treatment could not decrease CDK1 expression, suppress HCC cell proliferation, and induce G2/M cell cycle arrest.

DISCUSSION

Metformin-suppressed HCC cell proliferation was dependent on the inhibitory effect of miR-378 on CDK1 expression. Taken together, we concluded that metformin inhibited HCC cell proliferation via modulating miR-378/CDK1 axis.

CONCLUSION

Collectively, the current results provide the first evidence, to our knowledge, that miR-378/CDK1 axis is involved in metformin modulating the proliferation of HCC cells, which suggests a novel molecular mechanism underlying the thera peutic effect of metformin on HCC.

Combination of BEZ235 and Metformin Has Synergistic Effect on Cell Viability in Colorectal Cancer Cells

Patients with type II diabetes mellitus are more susceptible to colorectal cancer (CRC) incidence than non-diabetics. The anti-diabetic drug metformin is most commonly prescribed for the treatment of this disease and has recently shown antitumor effect in preclinical studies. The aberrant mutational activation in the components of RAS/RAF/MEK/ERK and PI3K/AKT/mTOR signaling pathway is very frequently observed in CRC. We previously reported that metformin inhibits the phosphorylation of ERK and BEZ235, a dual inhibitor of PI3K and mTOR, has anti-tumor activity against HCT15 CRC cells harboring mutations of KRAS and PIK3CA. Therefore, we hypothesized that simultaneous inhibition of two pathways by combining metformin with BEZ235 could be more effective in the suppression of proliferation than single agent treatment in HCT15 CRC cells. Here, we investigated the combinatory effect of metformin and BEZ235 on the cell survival in HCT15 CRC cells. Our study shows that both of the two signaling pathways can be blocked by this combinational strategy: metformin suppressed both pathways by inhibiting the phosphorylation of ERK, 4E-BP1 and S6, and BEZ235 suppressed PI3K/AKT/ mTOR pathway by reducing the phosphorylation of 4E-BP1 and S6. This combination treatment synergistically reduced cell viability. The combination index (CI) values ranged from 0.44 to 0.88, indicating synergism for the combination. These results offer a preclinical rationale for the potential therapeutic option for the treatment of CRC.

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.

Effect of hypoglycemic agents on survival outcomes of lung cancer patients with diabetes mellitus: A meta-analysis

BACKGROUND

To assess the association between hypoglycemic agents and prognosis of lung cancer patients with diabetes.

METHODS

A comprehensive literature search was performed in PubMed, Web of Science, Embase, and Cochrane Library until May 2017. The search yielded 2593 unique citations, of which 18 articles met inclusion criteria. The hazard ratios (HRs) and 95% confidence intervals (95% CIs) were calculated by a fixed-effects or random-effects model.

RESULTS

The pooled HRs favoring metformin users were 0.77 for overall survival (OS) (n = 15, 95% CI: 0.68-0.86) and 0.50 for disease-free survival (n = 5, 95% CI: 0.39-0.64). One study assessed the relationship between metformin and cancer-specific survival (CSS), reporting no significant results. No significant association between insulin and OS (n = 2, HR: 0.95, 95% CI: 0.79-1.13) or CSS (n = 2, HR: 1.03, 95% CI: 0.76-1.41) was noted. One study evaluated association of sulfonylureas with lung cancer survival and reported no clinical benefit (HR: 1.10, 95% CI: 0.87-1.40). One study reported no association of thiazolidinediones with lung cancer survival (HR: 1.04, 95% CI: 0.65-1.66).

CONCLUSIONS

This meta-analysis demonstrated that metformin exposure might improve survival outcomes in lung cancer patients with diabetes.

Metformin enhances the radiosensitivity of human liver cancer cells to γ-rays and carbon ion beams

The purpose of this study was to investigate the effect of metformin on the responses of hepatocellular carcinoma (HCC) cells to γ-rays (low-linear energy transfer (LET) radiation) and carbon-ion beams (high-LET radiation). HCC cells were pretreated with metformin and exposed to a single dose of γ-rays or carbon ion beams. Metformin treatment increased radiation-induced clonogenic cell death, DNA damage, and apoptosis. Carbon ion beams combined with metformin were more effective than carbon ion beams or γ-rays alone at inducing subG1 and decreasing G2/M arrest, reducing the expression of vimentin, enhancing phospho-AMPK expression, and suppressing phospho-mTOR and phospho-Akt. Thus, metformin effectively enhanced the therapeutic effect of radiation with a wide range of LET, in particular carbon ion beams and it may be useful for increasing the clinical efficacy of carbon ion beams.

BMP4 promotes oxaliplatin resistance by an induction of epithelial-mesenchymal transition via MEK1/ERK/ELK1 signaling in hepatocellular carcinoma

BACKGROUND

Bone morphogenetic protein-4 (BMP4) is a key regulator of epithelial-mesenchymal transition (EMT), which is crucial for cancer cells to acquire chemoresistance. The effects of BMP4 on OXA sensitivity in HCC need to be elucidated.

METHODS

Functional analysis of BMP4 on EMT-regulated OXA sensitivity was performed in human HCC specimens, in the HCC cell lines HepG2 and HCCLM3, and in a subcutaneous tumor model receiving OXA treatment. The downstream signaling targets of BMP4 in HCC were profiled and confirmed.

RESULTS

BMP4 expression was significantly increased in HCC tissue, and was correlated with tumor de-differentiation and unfavorable prognosis. BMP4 promoted HCC EMT and was correlated with OXA resistance. Blocking of BMP4 reversed EMT and increased OXA chemosensitivity in vitro and in vivo. ELK1, a transcription factor involved in EMT, was an important mediator of BMP4-induced OXA resistance in HCC. Blocking of MEK/ERK/ELK1 attenuated BMP4-induced EMT and enhanced OXA sensitivity.

CONCLUSIONS

BMP4 induces EMT and OXA chemoresistance via MEK/ERK/ELK1 signaling pathway in HCC. BMP4 may be a valuable therapeutic target for HCC patients receiving OXA-based chemotherapy.

The major Boswellia serrata active 3-acetyl-11-keto-β-boswellic acid strengthens interleukin-1α upregulation of matrix metalloproteinase-9 via JNK MAP kinase activation

BACKGROUND

Boswellia serrata gum resin has attracted pharmacological interest as an alternative antinflammatory.

PURPOSE

We studied the application of an ethanolic extract of the resin and its main active 3-O-acetyl-11-keto-β-boswellic acid (AKBA) against inflammatory degeneration of skin extracellular matrix.

STUDY DESIGN

We compared the effects of the extract and AKBA on the activity of MMP-2 and MMP-9 (72-kDa and 92-kDa type IV collagenases) in HaCaT keratinocytes exposed to interleukin-1α (IL-1α) as a skin inflammation model.

METHODS

MMP activity in cell conditioned medium was assayed by gelatin zymography, while NF-kB and MAP kinase activations were evaluated by Western blotting.

RESULTS

IL-1α (10 ng/ml) upregulated MMP-9 but not MMP-2 in HaCaT cells. The extract, used at 2.3, 4.6 and 9.3 µg/ml, had no effect, but in combination with IL-1α showed MMP-9 inhibition at the lowest dose and increased upregulation at the highest one. AKBA alone, at the same concentrations (corresponding to 5, 10, and 20 µM), did not stimulate MMP-9, but together with IL-1α induced an increased upregulation at the lowest dose that progressively disappeared at higher doses. WB analysis showed that IL-1α induced phosphorylation of NF-κB p65, while AKBA abolished this effect at 20 µM, but conversely increased it at 5 µM. Screening of MAP kinase phosphorylation showed a combined activation of IL-1α/AKBA on JNK, while the JNK inhibitor SP600125 abolished MMP-9 upregulation induced by IL-1α/AKBA.

CONCLUSION

The enhancing effect of IL-1α/AKBA on MMP-9 at low AKBA concentration seems to involve the activation of JNK-mediated NF-κB pathway. Conversely, the extract inhibits the IL-1α effect at low doses, but not at higher ones, where AKBA and possibly other β-boswellic acids reach concentrations that potentiate the effect of IL-1α. The extract at low doses could protect the skin against degenerative processes of extracellular matrix, while keto-β-boswellic acids seem unsuitable for this purpose.

Imbalanced immune responses involving inflammatory molecules and immune-related pathways in the lung of acute and subchronic arsenic-exposed mice

Inorganic arsenic has been claimed to increase the risk of pulmonary diseases through ingestion, as opposed to inhalation, which makes it a unique and intriguing environmental toxicant. However, the immunotoxic effects of lung, one of the targets of arsenic exposure, have not been extensively investigated in vivo. In the present study, we first confirmed that 2.5, 5 and 10mg/kg NaAsO₂ orally for 24h dose-dependently triggered the infiltration of neutrophils, lymphocytes and macrophages in BALF. Not only the transcription activity, but also the secretion of proinflammatory cytokines IL-1β, IL-6 and TNF-α were consistently raised in the lung and BALF of acute arsenic-exposed mice. Acute oral administration of NaAsO₂ also raised pulmonary MPO activity and mRNA levels of chemokine Mip-2 and Mcp-1. Meanwhile, obvious histopathological damages with inflammatory cells infiltration and erythrocyte aggregation around the capillaries were verified in the lung of mice drank arsenic-rich water freely for 3 months. Furthermore, we affirmed notable disturbance of CD4⁺ T-cell differentiation in the lung of acute arsenic-exposed mice, as demonstrated by up-regulated mRNA levels of regulator Gata3 and cytokine Il-4 of Th2, enhanced Foxp3 and Il-10 of Treg, down-regulated T-bet and Ifn-γ of Th1, as well as lessened Ror-γt and Il-23 of Th17. However, impressive elevation of cytokine Ifn-γ and Il-23, as well as moderate enhancement of Il-4 and Il-10 were found in the lung by subchronic arsenic administration. Finally, our present study demonstrated that both a single and sustained arsenic exposure prominently increased the expression of immune-related p38, JNK, ERK1/2 and NF-κB proteins in the lung tissue. While disrupting the pulmonary redox homeostasis by increasing MDA levels, exhausting GSH and impaired enzyme activities of CAT and GSH-Px, antioxidant regulator NRF2 and its downstream targets HO-1 and GSTO1/2 were also up-regulated by both acute and subchronic arsenic treatment. Conclusively, our present study demonstrated both acute and subchronic oral administration of arsenic triggers multiple pulmonary immune responses involving inflammatory molecules and T-cell differentiation, which might be closely associated with the imbalanced redox status and activation of immune-related MAPKs, NF-κB and anti-inflammatory NRF2 pathways.

β-mangostin suppresses human hepatocellular carcinoma cell invasion through inhibition of MMP-2 and MMP-9 expression and activating the ERK and JNK pathways

β-mangostin is a dietary xanthone that has been reported to have the anticancer properties in some human cancer cell types. However, the antimetastatic effect and molecular mechanism of β-mangostin action in human hepatocellular carcinoma (HCC) cells remain unknown. In this study, we found that β-mangostin did not induce cytotoxicity in human HCC cells (SK-Hep-1, Huh-7 and HA22T/VGH cells). β-mangostin could inhibit migration and invasion of human HCC cells. Meanwhile, β-mangostin significantly decreased the protein activities and expression of matrix metalloproteinase (MMP)-2 and MMP-9 via increasing the activation of MEK1/2, ERK1/2, MEK4 and JNK1/2 signaling pathways. Furthermore, using specific inhibitor for ERK1/2 (PD98059) and JNK1/2 (JNKII) significantly restored the expression of MMP-2/-9 and invasion by β-mangostin treatment in Huh-7 cells. In addition, β-mangostin effectively restored the protein levels and transcription activity of MMP-2 and MMP-9 in siERK or siJNK-transfected Huh-7 cells, concomitantly with promotion on cell migration and invasion. Taken together, these findings are the first to demonstrate the antimetastatic activity of β-mangostin against human HCC cells, which may act as a promising therapeutic agent for the treatment of HCC.

Suppressive effects on cell proliferation and motility in gastric cancer SGC-7901 cells by introducing ulinastatin in vitro

Ulinastatin (UTI) is a kind of urinary trypsin inhibitor regulating broad-spectrum proteases and is used widely in the treatment of inflammatory diseases. Some evidence has suggested that UTI has antitumor functions in human carcinomas, but its function in gastric cancer (GC) has not been discussed extensively. In this study, we investigated the effects of UTI on GC SGC-7901 cells in vitro by preincubating cells with the UTI. The expression of the related molecules, urokinase-type plasminogen activator (uPA), was investigated at both the mRNA and the protein stages. Activation of uPA was analyzed and the phosphorylation of ERK1/2 downstream uPA was detected. According to the results, UTI downregulated uPA expression and significantly suppressed the activation of uPA and the phosphorylation of ERK1/2. Furthermore, the SGC-7901 cells treated by UTI showed a significant decrease in cell proliferation and impairment of invasion and migration. However, no significant influence was observed on cell apoptosis. By ectopically expressing uPA in SGC-7901 cells, suppression effects of UTI were rescued. We suggest that UTI suppresses GC cell proliferation, motility, and at least partly conducted through uPA. Although the effects of UTI in GC cells need to be validated further, UTI represents a strong therapeutic strategy that is worth following up in GC treatment.

Metformin incombination with curcumin inhibits the growth, metastasis, and angiogenesis of hepatocellular carcinoma in vitro and in vivo

Hepatocellular carcinoma (HCC) has poor prognosis due to the advanced disease stages by the time it is diagnosed, high recurrence rates and metastasis. In the present study, we investigated the effects of metformin (a safe anti-diabetic drug) and curcumin (a turmeric polyphenol extracted from rhizome of Curcuma longa Linn.) on proliferation, apoptosis, invasion, metastasis, and angiogenesis of HCC in vitro and in vivo. It was found that co-treatment of metformin and curcumin could not only induce tumor cells into apoptosis through activating the mitochondria pathways, but also suppress the invasion, metastasis of HCC cells and angiogenesis of HUVECs. These effects were associated with downregulation of the expression of MMP2/9, VEGF, and VEGFR-2, up-regulation of PTEN, P53 and suppression of PI3K/Akt/mTOR/NF-κB and EGFR/STAT3 signaling. Co-administration of metformin and curcumin significantly inhibited HCC tumor growth than administration with metformin or curcumin alone in a xenograft mouse model. Thus, metformin and curcumin in combination showed a better anti-tumor effects in hepatoma cells than either metformin or curcumin presence alone and might represent an effective therapeutic strategy for HCC treatment.

Metformin ameliorates BSCB disruption by inhibiting neutrophil infiltration and MMP-9 expression but not direct TJ proteins expression regulation

Blood-spinal cord barrier (BSCB) disruption is a major process for the secondary injury of spinal cord injury (SCI) and is considered to be a therapeutic target for SCI. Previously, we demonstrated that metformin could improve functional recovery after SCI; however, the effect of metformin on BSCB is still unknown. In this study, we found that metformin could prevent the loss of tight junction (TJ) proteins at day 3 after SCI in vivo, but in vitro there was no significant difference of these proteins between control and metformin treatment in endothelial cells. This indicated that metformin-induced BSCB protection might not be mediated by up-regulating TJ proteins directly, but by inhibiting TJ proteins degradation. Thus, we investigated the role of metformin on MMP-9 and neutrophils infiltration. Neutrophils infiltration is the major source of the enhanced MMP-9 in SCI. Our results showed that metformin decreased MMP-9 production and blocked neutrophils infiltration at day 1 after injury, which might be related to ICAM-1 down-regulation. Also, our in vitro study showed that metformin inhibited TNF-α-induced MMP-9 up-regulation in neutrophils, which might be mediated via an AMPK-dependent pathway. Together, it illustrated that metformin prevented the breakdown of BSCB by inhibiting neutrophils infiltration and MMP-9 production, but not by up-regulating TJ proteins expression. Our study may help to better understand the working mechanism of metformin on SCI.

Inhibition of MMP-2 Expression Enhances the Antitumor Effect of Sorafenib in Hepatocellular Carcinoma by Suppressing the PI3K/AKT/mTOR Pathway

Sorafenib has been globally approved as the standard treatment for patients with advanced hepatocellular carcinoma (HCC). However, the response rate of HCC patients to sorafenib is limited because of tumor recurrence and metastasis. Therefore, seeking combined therapeutic strategies with sorafenib is necessary to improve the antitumor efficiency. Here we demonstrated that expression of MMP-2 is positively correlated with the migration ability of HCC cells. Cells with a higher MMP-2 expression (SK-HEP-1 cells) were less sensitive to sorafenib than those with lower MMP-2 expression (HepG2 cells). Cotreatment of cells with SB-3CT and sorafenib more strongly inhibited migration ability than with sorafenib treatment alone in both HCC cells with high and low expression of MMP-2. In vivo cell metastasis experiments confirmed the synergistic effects of sorafenib and SB-3CT in reducing lung metastasis of SK-HEP-1 cells. Mechanistically, we showed that the synergistic antitumor effect may be attributed to inhibition of the PI3K/AKT/mTOR signaling pathway, but not the RAF/MEK/ERK signaling pathway. With these results taken together, the current study demonstrates that inhibiting MMP-2 expression can enhance the antitumor effect of sorafenib in HCC cells with a high MMP-2 expression, which may provide a novel strategy to improve therapeutic efficiency in HCC.

Metformin promotes apoptosis in hepatocellular carcinoma through the CEBPD-induced autophagy pathway

Metformin, as an AMP-activated protein kinase (AMPK) activator, can activate autophagy. A study showed that metformin decreased the risk of hepatocellular carcinoma (HCC) in diabetic patients. However, the detailed mechanism in the metformin-mediated anticancer effect remains an open question. Transcription factor CCAAT/enhancer-binding protein delta (CEBPD) has been suggested to serve as a tumor suppressor and is responsive to multiple anticancer drugs in HCC. In this study, we found that CEBPD and autophagy are involved in metformin-induced cell apoptosis in Huh7 cells. The underlying mechanisms in this process included a reduction in Src-mediated CEBPD protein degradation and an increase in CEBPD-regulated LC3B and ATG3 gene transcription under metformin treatment. We also found that AMPK is involved in metformin-induced CEBPD expression. Combined treatment with metformin and rapamycin can enhance autophagic cell death through the AMPK-dependent and AMPK-independent pathway, respectively. Taken together, we provide a new insight and therapeutic approach by targeting autophagy in the treatment of HCC.

Prostaglandin E2 stimulates urokinase-type plasminogen activator receptor via EP2 receptor-dependent signaling pathways in human AGS gastric cancer cells

Aberrant expression of urokinase-type plasminogen activator receptor (uPAR) has been observed in human gastric cancers. Prostaglandin E2 (PGE2 ), whose biosynthesis is catalyzed by cyclooxygenase-2 (COX-2), is implicated in cancer metastasis; however, the cellular and molecular mechanisms of PGE2 -driven uPAR expression are yet to be elucidated in human gastric cancer AGS cells. In this study, we showed that PGE2 induces uPAR expression in concentration- and time-dependent manners. Furthermore, using antagonists and siRNA, we found that among the four subtypes of PGE2 receptors, EP2 receptors are involved in PGE2 -induced uPAR expression. PGE2 induced the activation of Src, epidermal growth factor receptor (EGFR), c-Jun NH2 -terminal kinase (JNK), extracellular signal-regulated kinase (Erk), and p38 mitogen activated protein kinase (p38 MAPK). Specific inhibitor and mutagenesis studies showed that Src, EGFR, JNK1/2, and Erk1/2 are involved in PGE2 -induced uPAR expression. PGE2 induces EP2-dependent phosphorylation of Src, while the activation of Src-dependent EGFR leads to the phosphorylation of JNK1/2 and Erk1/2. Deletion and site-directed mutagenesis studies demonstrated the involvement of transcription factor activator protein (AP)-1 and nuclear factor-kappa B (NF-κB) in PGE2 -induced uPAR expression. EGFR-dependent MAPKs (JNK1/2 and Erk1/2) function as the upstream signaling molecules in the activation of AP-1 and NF-κB, respectively. AGS cells pre-treated with PGE2 showed remarkably enhanced invasiveness, which was partially abrogated by uPAR-neutralizing antibodies. To the best of our knowledge, this is the first report that PGE2 -induced uPAR expression, which stimulates invasiveness of human gastric cancer AGS cells, is mediated by the EP2 receptor-dependent Src/EGFR/JNK1/2, Erk1/2/AP-1, and Src/EGFR/JNK1/2, Erk1/2/NF-κB cascades. © 2016 Wiley Periodicals, Inc.

Receptor tyrosine kinase inhibition by regorafenib/sorafenib inhibits growth and invasion of meningioma cells

Systemic chemotherapeutic treatment for unresectable and/or aggressive meningiomas is still unsatisfying. PDGF receptor (PDGFR)-mediated activation of mitogenic signalling has been shown to be active in meningiomas. Therefore, we evaluate in vitro and in vivo the effects of inhibiting PDGFR using the clinically well-characterised tyrosine kinase inhibitors sorafenib or regorafenib in meningioma models. IOMM-Lee meningioma cells were used to assess cytotoxic effects, inhibition of proliferation, induction of apoptosis, as well as inhibition of migration and motility by sorafenib and regorafenib. Using an orthotopic mouse xenograft model, growth inhibition as monitored by magnetic resonance imaging, and overall survival of sorafenib- or regorafenib-treated mice compared with control animals was determined. Treatment of malignant IOMM-Lee cells resulted in significantly reduced cell survival and induction of apoptosis following regorafenib and sorafenib treatment. Western blots showed that both drugs target phosphorylation of p44/42 ERK via downregulation of the PDGFR. Both drugs additionally showed significant inhibition of cell motility and invasion. In vivo, mice with orthotopic meningioma xenografts showed a reduced volume (n.s.) of signal enhancement in MRI (mainly tumour) following sorafenib and regorafenib treatment. This was translated in a significantly increased overall survival time (p ≤ 0.05) for regorafenib-treated mice. Analyses of in vivo-grown tumours demonstrated again reduced PDGFR expression and expression/phosphorylation of p44/42. Sorafenib and regorafenib show antitumour activity in vitro and in vivo by targeting PDGFR and p44/42 ERK signalling.