Metabolic roles of AMPK and metformin in cancer cells

Mito-LND and (E)-Akt inhibitor-IV: novel compounds inducing endoplasmic reticulum stress and ROS accumulation against hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related mortality. Although multi-kinase inhibitors can prolong the overall survival of late-stage HCC patients, the emergence of drug resistance diminishes these benefits, ultimately resulting in treatment failure. Therefore, there is an urgent need for novel and effective drugs to impede the progression of liver cancer.

METHODS

This study employed a concentration gradient increment method to establish acquired sorafenib or regorafenib-resistant SNU-449 cells. Cell viability was assessed using the cell counting kit-8 assay. A library of 793 bioactive small molecules related to metabolism screened compounds targeting both parental and drug-resistant cells. The screened compounds will be added to both the HCC parental cells and the drug-resistant cells, followed by a comprehensive assessment. Intracellular adenosine triphosphate (ATP) levels were quantified using kits. Flow cytometry was applied to assess cell apoptosis and reactive oxygen species (ROS). Real-time quantitative PCR studied relative gene expression, and western blot analysis assessed protein expression changes in HCC parental and drug-resistant cells. A xenograft model in vivo evaluated Mito-LND and (E)-Akt inhibitor-IV effects on liver tumors, with hematoxylin and eosin staining for tissue structure and immunohistochemistry staining for endoplasmic reticulum stress protein expression.

RESULTS

From the compound library, we screened out two novel compounds, Mito-LND and (E)-Akt inhibitor-IV, which could potently kill both parental cells and drug-resistant cells. Mito-LND could significantly suppress proliferation and induce apoptosis in HCC parental and drug-resistant cells by upregulating glycolytic intermediates and downregulating those of the tricarboxylic acid (TCA) cycle, thereby decreasing ATP production and increasing ROS. (E)-Akt inhibitor-IV achieved comparable results by reducing glycolytic intermediates, increasing TCA cycle intermediates, and decreasing ATP synthesis and ROS levels. Both compounds trigger apoptosis in HCC cells through the interplay of the AMPK/MAPK pathway and the endoplasmic reticulum stress response. In vivo assays also showed that these two compounds could significantly inhibit the growth of HCC cells and induce endoplasmic reticulum stress.

CONCLUSION

Through high throughput screening, we identified that Mito-LND and (E)-Akt inhibitor-IV are two novel compounds against both parental and drug-resistant HCC cells, which could offer new strategies for HCC patients.

Role of Autophagy and AMPK in Cancer Stem Cells: Therapeutic Opportunities and Obstacles in Cancer

Cancer stem cells represent a resilient subset within the tumor microenvironment capable of differentiation, regeneration, and resistance to chemotherapeutic agents, often using dormancy as a shield. Their unique properties, including drug resistance and metastatic potential, pose challenges for effective targeting. These cells exploit certain metabolic processes for their maintenance and survival. One of these processes is autophagy, which generally helps in energy homeostasis but when hijacked by CSCs can help maintain their stemness. Thus, it is often referred as an Achilles heel in CSCs, as certain cancers tend to depend on autophagy for survival. Autophagy, while crucial for maintaining stemness in cancer stem cells (CSCs), can also serve as a vulnerability in certain contexts, making it a complex target for therapy. Regulators of autophagy like AMPK (5' adenosine monophosphate-activated protein kinase) also play a crucial role in maintaining CSCs stemness by helping CSCs in metabolic reprogramming in harsh environments. The purpose of this review is to elucidate the interplay between autophagy and AMPK in CSCs, highlighting the challenges in targeting autophagy and discussing therapeutic strategies to overcome these limitations. This review focuses on previous research on autophagy and its regulators in cancer biology, particularly in CSCs, addresses the remaining unanswered questions, and potential targets for therapy are also brought to attention.

Shear Stress-Induced AMP-Activated Protein Kinase Modulation in Endothelial Cells: Its Role in Metabolic Adaptions and Cardiovascular Disease

Endothelial cells (ECs) line the inner surface of all blood vessels and form a barrier that facilitates the controlled transfer of nutrients and oxygen from the circulatory system to surrounding tissues. Exposed to both laminar and turbulent blood flow, ECs are continuously subject to differential mechanical stimulation. It has been well established that the shear stress associated with laminar flow (LF) is atheroprotective, while shear stress in areas with turbulent flow (TF) correlates with EC dysfunction. Moreover, ECs show metabolic adaptions to physiological changes, such as metabolic shifts from quiescence to a proliferative state during angiogenesis. The AMP-activated protein kinase (AMPK) is at the center of these phenomena. AMPK has a central role as a metabolic sensor in several cell types. Moreover, in ECs, AMPK is mechanosensitive, linking mechanosensation with metabolic adaptions. Finally, recent studies indicate that AMPK dysregulation is at the center of cardiovascular disease (CVD) and that pharmacological targeting of AMPK is a promising and novel strategy to treat CVDs such as atherosclerosis or ischemic injury. In this review, we summarize the current knowledge relevant to this topic, with a focus on shear stress-induced AMPK modulation and its consequences for vascular health and disease.

Autophagy inhibition potentiates energy restriction-induced cell death in hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) significantly contributes to cancer-related mortality due to the limited response of HCC to current anticancer therapies, thereby necessitating more effective treatment approaches. Energy restriction mimetic agents (ERMAs) have emerged as potential therapies in targeting the Warburg effect, a unique metabolic process in cancer cells. However, ERMAs exhibit limited efficacy when used as monotherapy. Additionally, ERMAs have been found to induce autophagy in cancer cells. The role of autophagy in cancer survival remains a subject of debate. Thus, it is crucial to ascertain whether ERMA-induced autophagy is a mechanism for cell survival or cell death in HCC. Our study aims to investigate the effect of autophagy inhibition on the survival of HCC cells treated with ERMAs while also examining the potential of combining an autophagy inhibitor such as spautin-1 with ERMAs to enhance HCC cell death. Our results suggest a cytoprotective role for ERMA-induced autophagy in HCC cells, as combining the autophagy inhibitor spautin-1 with ERMAs effectively suppressed ERMA-induced autophagy and synergistically enhanced their antitumor activity. The treatment combination promoted HCC death through apoptosis, cell cycle arrest, and inhibition of AKT and ERK activation, which are known to play a key role in cellular proliferation. Collectively, our findings highlight a potential strategy to combat HCC by combining energy restriction with autophagy inhibition.

Interferon-stimulated gene TDRD7 interacts with AMPK and inhibits its activation to suppress viral replication and pathogenesis

IMPORTANCE

Virus infection triggers induction of interferon (IFN)-stimulated genes (ISGs), which ironically inhibit viruses themselves. We identified Tudor domain-containing 7 (TDRD7) as a novel antiviral ISG, which inhibits viral replication by interfering with autophagy pathway. Here, we present a molecular basis for autophagy inhibitory function of TDRD7. TDRD7 interacted with adenosine monophosphate (AMP)-activated protein kinase (AMPK), the kinase that initiates autophagy, to inhibit its activation. We identified domains required for the interaction; deleting AMPK-interacting domain blocked antiAMPK and antiviral activities of TDRD7. We used primary cells and mice to evaluate the TDRD7-AMPK antiviral pathway. TDRD7-deficient primary mouse cells exhibited enhanced AMPK activation and viral replication. Finally, TDRD7 knockout mice showed increased susceptibility to respiratory virus infection. Therefore, our study revealed a new antiviral pathway of IFN and its contribution to host response. Our results have therapeutic potential; a TDRD7-derived peptide may be an effective AMPK inhibitor with application as antiviral agent.

Phase I / II trial of metformin as a chemo-radiosensitizer in a head and neck cancer patient population

OBJECTIVES

Retrospective studies have shown that head and neck squamous cell carcinoma (HNSCC) patients taking metformin demonstrate superior survival compared to their counterparts. We sought to determine whether metformin combined with chemoradiation would improve HNSCC patient survival compared to historical controls.

MATERIALS AND METHODS

We conducted a Phase I/II prospective, single arm clinical trial in patients with newly diagnosed HNSCC (NCT02949700). Patients received platinum-based chemoradiation in combination with orally dosed metformin at one of 2 doses- 850 mg BID or 1500 mg BID administered during radiation, with a 2-week lead-in phase. Toxicity, disease response and survival metrics were ascertained throughout the study period.

RESULTS

A total of 25 patients were evaluable for toxicity and survival; 9 failed to reach the predetermined 70% compliance with the study drug. No dose limiting toxicities were identified in the Phase I component and there were no grade 4 adverse events likely related to metformin throughout the study. The primary outcome for the Phase II component was met with a response rate of 96%. Three-year overall survival was ∼70% in the per protocol p16 + cohort and 0% in the per protocol p16- cohort. Survival among participants with a ≥70% metformin compliance to <70% metformin compliance demonstrated a trend towards improvement in the ≥70% compliance cohort, though this did not reach significance.

CONCLUSION

Metformin is well tolerated during concurrent chemoradiation for HNSCC. Its effectiveness as a chemo-radiosensitizer remains unclear and will require further study with randomized controlled clinical trials in this patient population.

Will metformin use lead to a decreased risk of thyroid cancer? A systematic review and meta-analyses

BACKGROUND

It has been reported that metformin use may reduce the risk of thyroid cancer, but existing studies have generated inconsistent results. The purpose of this study was to investigate such association between metformin use and the risk of thyroid cancer.

METHODS

Studies of metformin use for the risk of thyroid cancer were searched in Web of Science, PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, China Biomedical Database, Wanfang Data, and Chinese Scientific Journals Database (VIP) from the establishment date to December 2022. Newcastle-Ottawa scale is adopted for assessing the methodological quality of included studies, and the inter-study heterogeneity was assessed by using the I-squared statistic. Combined odds ratios (ORs) with the corresponding 95% confidence intervals (CIs) were calculated through either fixed-effects or random-effects model according to the heterogeneity. Besides, subgroup analyses, sensitivity analyses and test for publication bias were conducted.

RESULTS

Five studies involving 1,713,528 participants were enrolled in the qualitative and quantitative synthesis. The result of the meta-analyses showed that metformin use was associated with a statistically significant lower risk of thyroid cancer (pooled OR = 0.68, 95% CI = 0.50-0.91, P = 0.011). Moreover, in the subgroup analysis, we found that the use of metformin may also aid in the prevention of thyroid cancer in Eastern population (pooled OR = 0.55, 95% CI = 0.35-0.88, P = 0.012) rather than Western population (pooled OR = 0.89, 95% CI = 0.52-1.54, P = 0.685). Sensitivity analysis suggested the results of this meta-analyses were relatively stable. No publication bias was detected.

CONCLUSION

Metformin use is beneficial for reducing the risk of thyroid cancer. For further investigation, more well-designed studies are still needed to elucidate the association between metformin use and the risk of thyroid cancer.

Repurposing drugs targeting metabolic diseases for cancer therapeutics

Hurdles in the identification of new drugs for cancer treatment have made drug repurposing an increasingly appealing alternative. The approach involves the use of old drugs for new therapeutic purposes. It is cost-effective and facilitates rapid clinical translation. Given that cancer is also considered a metabolic disease, drugs for metabolic disorders are being actively repurposed for cancer therapeutics. In this review, we discuss the repurposing of such drugs approved for two major metabolic diseases, diabetes and cardiovascular disease (CVD), which have shown potential as anti-cancer treatment. We also highlight the current understanding of the cancer signaling pathways that these drugs target.

Utilizing metformin to prevent metabolic syndrome due to androgen deprivation therapy (ADT): a randomized phase II study of metformin in non-diabetic men initiating ADT for advanced prostate cancer

BACKGROUND

Androgen deprivation therapy (ADT) can lead to metabolic syndrome (MS) and is implicated in ADT-resistance. Metformin showed antineoplastic activity through mTOR inhibition secondary AMPK-activation.

MATERIALS AND METHODS

To investigate whether metformin mitigated ADT-related MS, we conducted a randomized double-blind phase II trial of metformin 500 mg TID or placebo in non-diabetic patients with biochemically-relapsed or advanced PC due for ADT. Fasting serum glucose, insulin, PSA, metformin, weight and waist circumference (WC) were measured at baseline, week 12 and 28. The primary endpoint was a group of MS metrics. Secondary endpoints include PSA response, safety, serum metformin concentrations and analysis of downstream an mTOR target, phospho-S6-kinase.

RESULTS

36 men were randomized to either metformin or placebo. Mean age was 68.4. Mean weight, WC and insulin levels increased in both arms. At week 12 and 28, no statistical differences in weight, WC or insulin were observed in either arm. No significant difference in percentage of patients with PSA <0.2 at week 28 between metformin (45.5%) vs. placebo (46.7%). Analysis in the metformin-arm showed variable down-regulation of phospho-S6 kinase.

CONCLUSIONS

In our small study, metformin added to ADT did not show a reduced risk of ADT-related MS or differences in PSA response.

Inhibition of pyruvate carboxylase reverses metformin resistance by activating AMPK in pancreatic cancer

AIMS

Pyruvate carboxylase (PC) plays a key role in cancer cell metabolic reprogramming. Whether metabolic reprogramming and PC are related in PDAC is unclear. Here, the effect of PC expression on PDAC tumorigenesis and metabolic reprogramming were evaluated.

MATERIALS AND METHODS

PC protein expression in PDAC and precancerous tissues was measured through immunohistochemistry. The maximum standardized uptake (SUVmax) of ¹⁸F-fluoro-2-deoxy-2-d-glucose (¹⁸F-FDG) in PDAC patient PET/CT scans before surgical resection was retrospectively determined. Stable PC-knockdown and PC-overexpressing cells were established using lentiviruses, and PDAC progression was assessed in vivo and in vitro. Lactate content, ¹⁸F-FDG cell uptake rate, mitochondrial oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) were measured in cells. RNA sequencing revealed and qPCR verified differentially expressed genes (DEGs) after PC knockdown. The signaling pathways involved were determined by Western blotting.

KEY FINDINGS

PC was significantly upregulated in PDAC tissues vs. precancerous tissues. A high SUVmax correlated with PC upregulation. PC knockdown significantly inhibited PDAC progression. Lactate content, SUVmax, and ECAR significantly decreased after PC knockdown. Peroxisome proliferator-activated receptor gamma coactivator-one alpha (PGC-1α) was upregulated after PC knockdown; and PGC1a expression promoted AMPK phosphorylation to activate mitochondrial metabolism. Metformin significantly inhibited mitochondrial respiration after PC knockdown, further activated AMPK and downstream carnitine palmitoyltransferase 1A (CPT1A)-regulated fatty acid oxidation (FAO), and inhibited PDAC cells progression.

SIGNIFICANCE

PDAC cell uptake of FDG was positively correlated with PC expression. PC promotes PDAC glycolysis, and reducing PC expression can increase PGC1a expression, activate AMPK, and restore metformin sensitivity.

The role of AMPK in cancer metabolism and its impact on the immunomodulation of the tumor microenvironment

Adenosine monophosphate-activated protein kinase (AMPK) is a key metabolic sensor that is pivotal for the maintenance of cellular energy homeostasis. AMPK contributes to diverse metabolic and physiological effects besides its fundamental role in glucose and lipid metabolism. Aberrancy in AMPK signaling is one of the determining factors which lead to the development of chronic diseases such as obesity, inflammation, diabetes, and cancer. The activation of AMPK and its downstream signaling cascades orchestrate dynamic changes in the tumor cellular bioenergetics. It is well documented that AMPK possesses a suppressor role in the context of tumor development and progression by modulating the inflammatory and metabolic pathways. In addition, AMPK plays a central role in potentiating the phenotypic and functional reprogramming of various classes of immune cells which reside in the tumor microenvironment (TME). Furthermore, AMPK-mediated inflammatory responses facilitate the recruitment of certain types of immune cells to the TME, which impedes the development, progression, and metastasis of cancer. Thus, AMPK appears to play an important role in the regulation of anti-tumor immune response by regulating the metabolic plasticity of various immune cells. AMPK effectuates the metabolic modulation of anti-tumor immunity via nutrient regulation in the TME and by virtue of its molecular crosstalk with major immune checkpoints. Several studies including that from our lab emphasize on the role of AMPK in regulating the anticancer effects of several phytochemicals, which are potential anticancer drug candidates. The scope of this review encompasses the significance of the AMPK signaling in cancer metabolism and its influence on the key drivers of immune responses within the TME, with a special emphasis on the potential use of phytochemicals to target AMPK and combat cancer by modulating the tumor metabolism.

Cancer of the Liver and its Relationship with Diabetes mellitus

A high increase witnessed in type II diabetes mellitus (T2DM) globally has increasingly posed a serious threat to global increases in liver cancer with the association between diabetes mellitus type II and the survival rate in liver cancer patients showing unstable findings. An increase in the development and progression of chronic liver disease from diabetes mellitus patients may be connected to cancer of the liver with several links such as Hepatitis B and C virus and heavy consumption of alcohol. The link between T2DM patients and liver cancer is centered on non-alcoholic fatty liver disease (NAFLD) which could be a serious threat globally if not clinically addressed. Several reports identified metformin treatment as linked to a lower risk of liver cancer prognosis while insulin treatment or sulphonylureas posed a serious threat. Mechanistically, the biological linkage between diabetes type II mellitus and liver cancer are still complex to understand with only the existence of a relationship between NAFLD and high level of energy intake and diabetes mellitus induces hepatic damage, increased liver weight thereby causes multiple pro-inflammatory cytokines that lead to the development of liver cancer. Therefore, this review gives an account of the pathophysiological importance of liver cancer position with T2DM, with the role of NAFLD as an important factor that bridges them.

Influence of antidiabetic drugs on glucose metabolism and immune response in patients with metastatic pancreatic ductal adenocarcinoma receiving gemcitabine plus nab-paclitaxel as first-line treatment

BACKGROUND

Association between pancreatic ductal adenocarcinoma (PDAC) and type 2 diabetes mellitus (DM2) has long been evaluated. Indeed, DM2 can be both an epiphenomenon of PDAC and a risk factor. The present study aimed to investigate the correlation between overall survival (OS) and antidiabetic drugs in patients with metastatic pancreatic ductal adenocarcinoma and DM2.

METHOD

Data from 232 patients were collected retrospectively from 2014 to 2021. 174 from AOU Cagliari Medical Oncology and 58 from AOU Ancona Medical Oncology. All patients received gemcitabine plus nab-paclitaxel first-line chemotherapy. We aimed to evaluate the correlation between DM2, anti-diabetic medications and overall survival. Survival distribution was assessed by Kaplan-Meier curves.

RESULTS

Median age was 68±9, 127 (55%) were male. 138/232 (59%) patients were not affected by DM2, 94/232 (41%) were affected by DM2. 57 were insulin-treated and 37 were metformin-treated. DM2 treated patients showed an higher median overall survival (26 vs 12 months, p = 0,0002). Among DM2 patients insulin-treated and metformin-treated showed an mOS of 21 months and 33 months, respectively.

CONCLUSIONS

Results showed a correlation between treated DM2 and higher mOS in patients with mPDAC. Limitations due to retrospective data collection must be considered. Further studies in this setting are needed.

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.

The role of pyroptosis and its crosstalk with immune therapy in breast cancer

Pyroptosis is a brand-new category of programmed cell death (PCD) that is brought on by multitudinous inflammasomes, which can recognize several stimuli to pilot the cleavage of and activate inflammatory cytokines like IL-18 and IL-1β is believed to have dual effects on the development of multiple cancers including breast cancer. However, pyroptosis has different effects on cancers depending on the type of tissues and their distinct heredity. Recently, the association between pyroptosis and breast cancer has received more and more attention, and it is thought that inducing pyroptosis could be used as a cancer treatment option. In addition, a great deal of evidence accumulating over the past decades has evinced the crosstalk between pyroptosis and tumor immunological therapy. Thus, a comprehensive summary combining the function of pyroptosis in breast cancer and antitumor immunity is imperative. We portray the prevalent knowledge of the multidimensional roles of pyroptosis in cancer and summarize the pyroptosis in breast cancer principally. Moreover, we elucidate the influence of inflammasomes and pyroptosis-produced cytokines on the tumor microenvironment (TME) of breast cancer. Taken together, we aim to provide a clue to harness pyroptosis rationally and apply it to augment immunotherapy efficiency for breast cancer.

Metformin in Differentiated Thyroid Cancer: Molecular Pathways and Its Clinical Implications

Metformin is a synthetic biguanide that improves insulin sensitivity and reduces hepatic gluconeogenesis. Aside being the first-line therapy for Type 2 Diabetes (T2D), many pleiotropic effects have been discovered in recent years, such as its capacity to reduce cancer risk and tumorigenesis. Although widely studied, the effect of metformin on thyroid cancer remains controversial. Potential mechanisms for its growth inhibitory effects have been elucidated in various preclinical studies that involved pathways related to adenosine mono-phosphate-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), mitochondrial glycerophosphate dehydrogenase (mGPDH), and the nuclear factor κB (NF-κB). Hyperinsulinemia increases cell glucose uptake and oxidative stress, and promotes thyroid cell growth, leading to hyperproliferation, carcinogenesis, and the development of malignant tumors. Furthermore, it has also been related to thyroid nodules size in nodular disease, as well as tumoral size in patients with thyroid cancer. Several clinical studies concluded that metformin might have an important role as an adjuvant therapy to reduce the growth of benign and malignant thyroid neoplasms. This suggests that metformin might be useful for patients with differentiated or poorly differentiated thyroid cancer and metabolic diseases such as insulin resistance or diabetes.

Pharmacological Effects of Panduratin A on Renal Cyst Development in In Vitro and In Vivo Models of Polycystic Kidney Disease

Renal cyst expansion in polycystic kidney disease (PKD) involves abnormalities in both cyst-lining-cell proliferation and fluid accumulation. Suppression of these processes may retard the progression of PKD. Evidence suggests that the activation of 5' AMP-activated protein kinase (AMPK) inhibits cystic fibrosis transmembrane conductance regulator (CFTR)-mediated chloride secretion, leading to reduced progression of PKD. Here we investigated the pharmacological effects of panduratin A, a bioactive compound known as an AMPK activator, on CFTR-mediated chloride secretion and renal cyst development using in vitro and animal models of PKD. We demonstrated that AMPK was activated in immortalized normal renal cells and autosomal dominant polycystic kidney disease (ADPKD) cells following treatment with panduratin A. Treatment with panduratin A reduced the number of renal cyst colonies corresponding with a decrease in cell proliferation and phosphorylated p70/S6K, a downstream target of mTOR signaling. Additionally, panduratin A slowed cyst expansion via inhibition of the protein expression and transport function of CFTR. In heterozygous Han:Sprague-Dawley (Cy/+) rats, an animal model of PKD, intraperitoneal administration of panduratin A (25 mg/kg BW) for 5 weeks significantly decreased the kidney weight per body weight ratios and the cystic index. Panduratin A also reduced collagen deposition in renal tissue. Intraperitoneal administration of panduratin A caused abdominal bleeding and reduced body weight. However, 25 mg/kg BW of panduratin A via oral administration in the PCK rats, another non-orthologous PKD model, showed a significant decrease in the cystic index without severe adverse effects, indicating that the route of administration is critical in preventing adverse effects while still slowing disease progression. These findings reveal that panduratin A might hold therapeutic properties for the treatment of PKD.

Discovery and repurposing of artemisinin

Malaria is an ancient infectious disease that threatens millions of lives globally even today. The discovery of artemisinin, inspired by traditional Chinese medicine (TCM), has brought in a paradigm shift and been recognized as the “best hope for the treatment of malaria” by World Health Organization. With its high potency and low toxicity, the wide use of artemisinin effectively treats the otherwise drug-resistant parasites and helps many countries, including China, to eventually eradicate malaria. Here, we will first review the initial discovery of artemisinin, an extraordinary journey that was in stark contrast with many drugs in western medicine. We will then discuss how artemisinin and its derivatives could be repurposed to treat cancer, inflammation, immunoregulation-related diseases, and COVID-19. Finally, we will discuss the implications of the “artemisinin story” and how that can better guide the development of TCM today. We believe that artemisinin is just a starting point and TCM will play an even bigger role in healthcare in the 21st century.

Pyroptosis and Its Regulation in Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DbCM) is a prevalent disease, characterized by contractile dysfunction and left ventricular hypertrophy. Patients with DbCM have high morbidity and mortality worldwide. Recent studies have identified that pyroptosis, a kind of cell death, could be induced by hyperglycemia involved in the formation of DbCM. This review summarizes the regulatory mechanisms of pyroptosis in DbCM, including NOD-like receptor3, AIM2 inflammasome, long non-coding RNAs, microRNAs, circular RNA, autophagy, and some drugs.

Dual anticancer role of metformin: an old drug regulating AMPK dependent/independent pathways in metabolic, oncogenic/tumorsuppresing and immunity context

Metformin has been known to treat type 2 diabetes for decades and is widely prescribed antidiabetic drug. Recently, its anticancer potential has also been discovered. Moreover, metformin has low cost thus it has attained profound research interest. Comprehensing the complexity of the molecular regulatory networks in cancer provides a mode for advancement of research in cancer development and treatment. Metformin targets many pathways that play an important role in cancer cell survival outcome. Here, we described anticancer activity of metformin on the AMPK dependent/independent mechanisms regulating metabolism, oncogene/tumor suppressor signaling pathways together with the issue of clinical studies. We also provided brief overwiev about recently described metformin's role in cancer immunity. Insight in these complex molecular networks, will simplify application of metformin in clinical trials and contribute to improvement of anti-cancer therapy.

Metformin and Dichloroacetate Suppress Proliferation of Liver Cancer Cells by Inhibiting mTOR Complex 1

The Warburg effect is important for cancer cell proliferation. This phenomenon can be flexible by interaction between glycolysis and mitochondrial oxidation for energy production. We aimed to investigate the anticancer effects of the pyruvate dehydrogenase kinase inhibitor, dichloroacetate (DCA) and the mitochondrial respiratory complex I inhibitor metformin in liver cancer cells. The anticancer effect of DCA and/or metformin on HepG2, PLC/PRF5 human liver cancer cell lines, MH-134 murine hepatoma cell lines, and primary normal hepatocytes using MTT assay. Inhibition of lactate/ATP production and intracellular reactive oxygen species generation by DCA and metformin was investigated. Inhibition of PI3K/Akt/mTOR complex I was evaluated to see whether it occurred through AMPK signaling. Anticancer effects of a combination treatment of DCA and metformin were evaluated in HCC murine model. The results showed that metformin and DCA effectively induced apoptosis in liver cancer cells. A combination treatment of metformin and DCA did not affect viability of primary normal hepatocytes. Metformin upregulated glycolysis in liver cancer cells, thereby increasing sensitivity to the DCA treatment. Metformin and DCA inhibited mTOR complex I signaling through upregulated AMPK-independent REDD1. In addition, metformin and DCA increased reactive oxygen species levels in liver cancer cells, which induced apoptosis. A combination treatment of metformin and DCA significantly suppressed the tumor growth of liver cancer cells using in vivo xenograft model. Taken together, the combined treatment of metformin and DCA suppressed the growth of liver cancer cells. This strategy may be effective for patients with advanced liver cancer.

Repurposing metformin for the treatment of gastrointestinal cancer

Diabetes mellitus type 2 and cancer share many risk factors. The pleiotropic insulin-dependent and insulin-independent effects of metformin might inhibit pathways that are frequently amplified in neoplastic tissue. Particularly, modulation of inflammation, metabolism, and cell cycle arrest are potential therapeutic cancer targets utilized by metformin to boost the anti-cancer effects of chemotherapy. Studies in vitro and in vivo models have demonstrated the potential of metformin as a chemo- and radiosensitizer, besides its chemopreventive and direct therapeutic activity in digestive system (DS) tumors. Hence, these aspects have been considered in many cancer clinical trials. Case-control and cohort studies and associated meta-analyses have evaluated DS cancer risk and metformin usage, especially in colorectal cancer, pancreatic cancer, and hepatocellular carcinoma. Most clinical studies have demonstrated the protective role of metformin in the risk for DS cancers and survival rates. On the other hand, the ability of metformin to enhance the actions of chemotherapy for gastric and biliary cancers is yet to be investigated. This article reviews the current findings on the anti-cancer mechanisms of metformin and its apparatus from pre-clinical and ongoing studies in DS malignancies.

AMPK activation by ASP4132 inhibits non-small cell lung cancer cell growth

Activation of adenosine monophosphate-activated protein kinase (AMPK) is able to produce significant anti-non-small cell lung cancer (NSCLC) cell activity. ASP4132 is an orally active and highly effective AMPK activator. The current study tested its activity against NSCLC cells. In primary NSCLC cells and established cell lines (A549 and NCI-H1944) ASP4132 potently inhibited cell growth, proliferation and cell cycle progression as well as cell migration and invasion. Robust apoptosis activation was detected in ASP4132-treated NSCLC cells. Furthermore, ASP4132 treatment in NSCLC cells induced programmed necrosis, causing mitochondrial p53-cyclophilin D (CyPD)-adenine nucleotide translocase 1 (ANT1) association, mitochondrial depolarization and medium lactate dehydrogenase release. In NSCLC cells ASP4132 activated AMPK signaling, induced AMPKα1-ACC phosphorylation and increased AMPK activity. Furthermore, AMPK downstream events, including mTORC1 inhibition, receptor tyrosine kinases (PDGFRα and EGFR) degradation, Akt inhibition and autophagy induction, were detected in ASP4132-treated NSCLC cells. Importantly, AMPK inactivation by AMPKα1 shRNA, knockout (using CRISPR/Cas9 strategy) or dominant negative mutation (T172A) almost reversed ASP4132-induced anti-NSCLC cell activity. Conversely, a constitutively active AMPKα1 (T172D) mimicked and abolished ASP4132-induced actions in NSCLC cells. In vivo, oral administration of a single dose of ASP4132 largely inhibited NSCLC xenograft growth in SCID mice. AMPK activation, mTORC1 inhibition and EGFR-PDGFRα degradation as well as Akt inhibition and autophagy induction were detected in ASP4132-treated NSCLC xenograft tumor tissues. Together, activation of AMPK by ASP4132 potently inhibits NSCLC cell growth in vitro and in vivo.

Metabolic Aspects of Anthracycline Cardiotoxicity

OPINION STATEMENT

Heart failure (HF) is increasingly recognized as the major complication of chemotherapy regimens. Despite the development of modern targeted therapies such as monoclonal antibodies, doxorubicin (DOXO), one of the most cardiotoxic anticancer agents, still remains the treatment of choice for several solid and hematological tumors. The insurgence of cardiotoxicity represents the major limitation to the clinical use of this potent anticancer drug. At the molecular level, cardiac side effects of DOXO have been associated to mitochondrial dysfunction, DNA damage, impairment of iron metabolism, apoptosis, and autophagy dysregulation. On these bases, the antioxidant and iron chelator molecule, dexrazoxane, currently represents the unique FDA-approved cardioprotectant for patients treated with anthracyclines.A less explored area of research concerns the impact of DOXO on cardiac metabolism. Recent metabolomic studies highlight the possibility that cardiac metabolic alterations may critically contribute to the development of DOXO cardiotoxicity. Among these, the impairment of oxidative phosphorylation and the persistent activation of glycolysis, which are commonly observed in response to DOXO treatment, may undermine the ability of cardiomyocytes to meet the energy demand, eventually leading to energetic failure. Moreover, increasing evidence links DOXO cardiotoxicity to imbalanced insulin signaling and to cardiac insulin resistance. Although anti-diabetic drugs, such as empagliflozin and metformin, have shown interesting cardioprotective effects in vitro and in vivo in different models of heart failure, their mechanism of action is unclear, and their use for the treatment of DOXO cardiotoxicity is still unexplored.This review article aims at summarizing current evidence of the metabolic derangements induced by DOXO and at providing speculations on how key players of cardiac metabolism could be pharmacologically targeted to prevent or cure DOXO cardiomyopathy.

Genome-Scale CRISPR-Cas9 Transcriptional Activation Screening in Metformin Resistance Related Gene of Prostate Cancer

Metformin is a classic type II diabetes drug which possesses anti-tumor properties for various cancers. However, different cancers do not respond to metformin with the same effectiveness or acquire resistance. Thus, searching for vulnerabilities of metformin-resistant prostate cancer is a promising strategy to improve the therapeutic efficiency of the drug. A genome-scale CRISPR-Cas9 activation library search targeting 23,430 genes was conducted to identify the genes that confer resistance to metformin in prostate cancer cells. Candidate genes were selected by total reads of sgRNA and sgRNA diversity, and then a CCK8 assay was used to verify their resistance to metformin. Interestingly, we discovered that the activation of ECE1, ABCA12, BPY2, EEF1A1, RAD9A, and NIPSNAP1 contributed to in vitro resistance to metformin in DU145 and PC3 cell lines. Notably, a high level of RAD9A, with poor prognosis in PCa, was the most significant gene in the CCK8 assay. Furthermore, we discerned the tumor immune microenvironment with RAD9A expression by CIBERSORT. These results suggested that a high level of RAD9A may upregulate regulatory T cells to counterbalance metformin in the tumor immune microenvironment.

Improvement Effect of Metformin on Female and Male Reproduction in Endocrine Pathologies and Its Mechanisms

Metformin (MF), a first-line drug to treat type 2 diabetes mellitus (T2DM), alone and in combination with other drugs, restores the ovarian function in women with polycystic ovary syndrome (PCOS) and improves fetal development, pregnancy outcomes and offspring health in gestational diabetes mellitus (GDM) and T2DM. MF treatment is demonstrated to improve the efficiency of in vitro fertilization and is considered a supplementary drug in assisted reproductive technologies. MF administration shows positive effect on steroidogenesis and spermatogenesis in men with metabolic disorders, thus MF treatment indicates prospective use for improvement of male reproductive functions and fertility. MF lacks teratogenic effects and has positive health effect in newborns. The review is focused on use of MF therapy for restoration of female and male reproductive functions and improvement of pregnancy outcomes in metabolic and endocrine disorders. The mechanisms of MF action are discussed, including normalization of metabolic and hormonal status in PCOS, GDM, T2DM and metabolic syndrome and restoration of functional activity and hormonal regulation of the gonadal axis.

Metformin induces apoptosis and inhibits migration by activating the AMPK/p53 axis and suppressing PI3K/AKT signaling in human cervical cancer cells

Human cervical cancer is the fourth most common malignancy among women worldwide, and it is expected to result in 460,000 deaths per year by 2040. Moreover, patients with cervical cancer often display drug resistance and severe side effects; therefore, the development of effective novel chemotherapeutic agents is important. In the present study, the effects of metformin, a first-line therapeutic drug for type 2 diabetes mellitus, were evaluated in cervical cancer. Compared with the control group, metformin significantly inhibited cell viability and migration, and induced apoptosis and cell cycle arrest in human cervical cancer cell lines (CaSki and HeLa). Following metformin treatment, the protein expression levels of p-AMP-activated protein kinase (p-AMPK), which promotes cell death, and the tumor suppressor protein p-p53 were remarkably upregulated in CaSki and C33A cells compared with the control group. Furthermore, compared with the control group, metformin significantly suppressed the PI3K/AKT signaling pathway in CaSki, C33A and HeLa cells. Compound C (an AMPK inhibitor) significantly reversed the effects of metformin on CaSki, C33A and HeLa cell viability, and AMPK and p53 phosphorylation. The results of the present study suggested that metformin induced AMPK-mediated apoptosis, thus metformin may serve as a chemotherapeutic agent for human cervical cancer.

The disubstituted adamantyl derivative LW1564 inhibits the growth of cancer cells by targeting mitochondrial respiration and reducing hypoxia-inducible factor (HIF)-1α accumulation

Targeting cancer metabolism has emerged as an important cancer therapeutic strategy. Here, we describe the synthesis and biological evaluation of a novel class of hypoxia-inducible factor (HIF)-1α inhibitors, disubstituted adamantyl derivatives. One such compound, LW1564, significantly suppressed HIF-1α accumulation and inhibited the growth of various cancer cell lines, including HepG2, A549, and HCT116. Measurements of the oxygen consumption rate (OCR) and ATP production rate revealed that LW1564 suppressed mitochondrial respiration, thereby increasing the intracellular oxygen concentration to stimulate HIF-1α degradation. LW1564 also significantly decreased overall ATP levels by inhibiting mitochondrial electron transport chain (ETC) complex I and downregulated mammalian target of rapamycin (mTOR) signaling by increasing the AMP/ATP ratio, which increased AMP-activated protein kinase (AMPK) phosphorylation. Consequently, LW1564 promoted the phosphorylation of acetyl-CoA carboxylase, which inhibited lipid synthesis. In addition, LW1564 significantly inhibited tumor growth in a HepG2 mouse xenograft model. Taken together, the results indicate that LW1564 inhibits the growth of cancer cells by targeting mitochondrial ETC complex I and impairing cancer cell metabolism. We, therefore, suggest that LW1564 may be a potent therapeutic agent for a subset of cancers that rely on oxidative phosphorylation for ATP generation.

A drug that curbs the accumulation of a critical protein involved in the oxygen-sensing machinery of cells could offer a potent new therapeutic for treating cancer. Inhyub Kim, University of Science and Technology, Daejeon, South Korea, and colleagues describe a compound called LW1564 that suppresses metabolism within mitochondria, the energy factories of the cell. Less energy production means less oxygen consumption and therefore oxygen molecules build up inside the cell, which in turn stimulates the degradation of HIF-1α, a master regulator of oxygen balance. Many tumors rely on HIF-1α for their aberrant biological characteristics, and without this protein they tend to show reduced growth. The authors demonstrated that LW1564 could limit HIF-1α accumulation and inhibit the proliferation of various cancer cell lines. The drug also inhibited tumor growth in a mouse model of liver cancer.

Metformin Suppresses Cancer Stem Cells through AMPK Activation and Inhibition of Protein Prenylation of the Mevalonate Pathway in Colorectal Cancer

Simple Summary

Tumor suppressing effect of metformin has been reported, and one of mechanism of this effect is suppression of cancer stem cells (CSCs). However, detailed mechanism of metformin-induced CSC-inhibitory effect has not been known. We demonstrated that the CSC-suppressive effect of metformin was associated with AMPK activation/mTOR inhibition and repression of protein prenylation through suppression of mevalonate pathway in colorectal cancer. Further studies would be needed to investigate cross-reactions with other mechanisms of the antitumor effect of metformin, and clinical impact of metformin should be considered as chemopreventive or adjunctive treatment for colorectal tumor.

Abstract

Metformin is a well-known AMPK (AMP-activated protein kinase) activator that suppresses cancer stem cells (CSCs) in some cancers. However, the mechanisms of the CSC-suppressing effects of metformin are not yet well understood. In this study, we investigated the CSC-suppressive effect of metformin via the mevalonate (MVA) pathway in colorectal cancer (CRC). Two colorectal cancer cell lines, HT29 and DLD-1 cells, were treated with metformin, mevalonate, or a combination of the two. We measured CSC populations by flow cytometric analysis (CD44+/CD133+) and by tumor spheroid growth. The expression of p-AMPK, mTORC1 (pS6), and key enzymes (HMGCR, FDPS, GGPS1, and SQLE) of the MVA pathway was also analyzed. We investigated the effects of metformin and/or mevalonate in xenograft mice using HT29 cells; immunohistochemical staining for CSC markers and key enzymes of the MVA pathway in tumor xenografts was performed. In both HT29 and DLD-1 cells, the CSC population was significantly decreased following treatment with metformin, AMPK activator (AICAR), HMG-CoA reductase inhibitor (simvastatin), or mTOR inhibitor (rapamycin), and was increased by mevalonate. The CSC-suppressing effect of these drugs was attenuated by mevalonate. The results of tumor spheroid growth matched those of the CSC population experiments. Metformin treatment increased p-AMPK and decreased mTOR (pS6) expression; these effects were reversed by addition of mevalonate. The expression of key MVA pathway enzymes was significantly increased in tumor spheroid culture, and by addition of mevalonate, and decreased upon treatment with metformin, AICAR, or rapamycin. In xenograft experiments, tumor growth and CSC populations were significantly reduced by metformin, and this inhibitory effect of metformin was abrogated by combined treatment with mevalonate. Furthermore, in the MVA pathway, CSC populations were reduced by inhibition of protein prenylation with a farnesyl transferase inhibitor (FTI-277) or a geranylgeranyl transferase inhibitor (GGTI-298), but not by inhibition of cholesterol synthesis with a squalene synthase inhibitor (YM-53601). In conclusion, the CSC-suppressive effect of metformin was associated with AMPK activation and repression of protein prenylation through MVA pathway suppression in colorectal cancer.

Cancer Stem Cells as a Potential Target to Overcome Multidrug Resistance

Multidrug resistance (MDR), which is a significant impediment to the success of cancer chemotherapy, is attributable to various defensive mechanisms in cancer. Initially, overexpression of ATP-binding cassette (ABC) transporters such as P-glycoprotein (P-gp) was considered the most important mechanism for drug resistance; hence, many investigators for a long time focused on the development of specific ABC transporter inhibitors. However, to date their efforts have failed to develop a clinically applicable drug, leaving only a number of problems. The concept of cancer stem cells (CSCs) has provided new directions for both cancer and MDR research. MDR is known to be one of the most important features of CSCs and thus plays a crucial role in cancer recurrence and exacerbation. Therefore, in recent years, research targeting CSCs has been increasing rapidly in search of an effective cancer treatment. Here, we review the drugs that have been studied and developed to overcome MDR and CSCs, and discuss the limitations and future perspectives.

Metformin protects against ischaemic myocardial injury by alleviating autophagy-ROS-NLRP3-mediated inflammatory response in macrophages

Myocardial ischaemia is usually accompanied by inflammatory response which plays a critical role in the myocardial healing and scar formation, while persistent inflammatory response contributes greatly to the myocardial remodeling and consequent heart failure. Metformin (Met), a widely used hypoglycemic drug, has increasingly been shown to exert remarkable cardioprotective effect on ischaemic myocardial injury such as acute myocardial infarction (AMI). However, the underlying mechanisms are still far from being fully understood. In this study, a mouse model of AMI was established through ligating the left anterior descending coronary artery (LAD), 100 mg/kg Met was given immediately after operation once daily for 3 days. It was demonstrated that Met effectively improved the cardiac haemodynamics (LVSP, LVEDP, +dp/dt, -dp/dt), diminished the infarct size, alleviated the disarrangement of myocardial cells and reduced the infiltration of inflammatory cells (macrophages, neutrophils and lymphocytes) in the heart of AMI mice. Mechanistically, Met decreased the expression of NLRP3 and enhanced the accumulation of LC3 puncta in F4/80-positive macrophages in the heart of AMI mice. Single cell suspension of cardiac macrophages was prepared from AMI mice and exhibited increased NLRP3 mRNA and protein expression. In contrast, Met decreased the expression of NLRP3 and p62, whereas increased the ratio of LC3II/LC3I. Additionally, both conditioned medium from H9c2 cardiomyocytes exposed to hydrogen peroxide (H9c2-H₂O₂-CM) and combination of mtDNA and ATP (mtDNA-ATP) increased the expression of NLRP3 and cleaved caspase-1 (p10) as well as intracellular ROS production in RAW264.7 macrophages, which were abrogated by Met treatment. Strikingly, chloroquine (CQ), 3-methyladenine (3-MA) and knockdown of autophagy-related gene (Atg5) abrogated the inhibitory effects of Met on H9c2-H₂O₂-CM and mtDNA-ATP-induced NLRP3 expression, release of IL-1β and IL-18 as well as ROS production in RAW264.7 macrophages. Collectively, these findings suggest that Met protects against ischaemic myocardial injury through alleviating autophagy-ROS-NLRP3 axis-mediated inflammatory response in macrophages.

Insulin Resistance in Osteoarthritis: Similar Mechanisms to Type 2 Diabetes Mellitus

Osteoarthritis (OA) and type 2 diabetes mellitus (T2D) are two of the most widespread chronic diseases. OA and T2D have common epidemiologic traits, are considered heterogenic multifactorial pathologies that develop through the interaction of genetic and environmental factors, and have common risk factors. In addition, both of these diseases often manifest in a single patient. Despite differences in clinical manifestations, both diseases are characterized by disturbances in cellular metabolism and by an insulin-resistant state primarily associated with the production and utilization of energy. However, currently, the primary cause of OA development and progression is not clear. In addition, although OA is manifested as a joint disease, evidence has accumulated that it affects the whole body. As pathological insulin resistance is viewed as a driving force of T2D development, now, we present evidence that the molecular and cellular metabolic disturbances associated with OA are linked to an insulin-resistant state similar to T2D. Moreover, the alterations in cellular energy requirements associated with insulin resistance could affect many metabolic changes in the body that eventually result in pathology and could serve as a unified mechanism that also functions in many metabolic diseases. However, these issues have not been comprehensively described. Therefore, here, we discuss the basic molecular mechanisms underlying the pathological processes associated with the development of insulin resistance; the major inducers, regulators, and metabolic consequences of insulin resistance; and instruments for controlling insulin resistance as a new approach to therapy.

Metformin activates AMPK/SIRT1/NF-κB pathway and induces mitochondrial dysfunction to drive caspase3/GSDME-mediated cancer cell pyroptosis

Pyroptosis is a form of programmed cell death initiated by inflammasomes and is critical for immunity. SIRT1, a NAD+-dependent deacetylase, plays multiple roles in inflammatory response and immunity. Metformin can activate SIRT1 to participate in different biological processes and exert its anticancer effects. However, the mechanism by which metformin activates SIRT1 to drive cancer cell pyroptosis has not been reported. In this study, we treated cancer cells with metformin for diverse periods of time (0-24 h) and found that cell viability was decreased obviously. Interestingly, pyroptosis occurred when cancer cells were treated with metformin for the indicated time (4, 8 and 12 h), which was elucidated by the cell swelling and bubbles blowing in the membrane. Metformin also increased the release of lactate dehydrogenase (LDH, an indication of pyroptotic cell cytotoxicity) remarkably. The underlying mechanisms were that metformin enhanced AMPK/SIRT1 pathway and further increased NF-κB p65 expression to stimulate Bax activation and cytochrome c release, triggering caspase3 cleavage of GSDME, which is a characteristic pyroptotic marker. Depletion of SIRT1 inhibited metformin-induced these protein expression, revealing that metformin promotes AMPK/SIRT1/NF-κB signaling to drive cancer cell pyroptosis. Meantime, metformin induced mitochondrial dysfunction to trigger activation of caspase3 and generation of GSDME-N. Moreover, mitochondrial dysfunction activated AMPK/SIRT1 pathway to cause pyroptotic death upon metformin treatment. This research firstly reveals that metformin as a sensitizer amplifies AMPK/SIRT1/NF-κB signaling to induce caspase3/GSDME-mediated cancer cell pyroptosis. Induction of cellular pyroptosis by metformin is considered as a novel therapeutic option against various cancers.

Moderation of mitochondrial respiration mitigates metabolic syndrome of aging

Deregulation of mitochondrial dynamics leads to the accumulation of oxidative stress and unhealthy mitochondria; consequently, this accumulation contributes to premature aging and alterations in mitochondria linked to metabolic complications. We postulate that restrained mitochondrial ATP synthesis might alleviate age-associated disorders and extend healthspan in mammals. Herein, we prepared a previously discovered mitochondrial complex IV moderate inhibitor in drinking water and orally administered to standard-diet-fed, wild-type C57BL/6J mice every day for up to 16 mo. No manifestation of any apparent toxicity or deleterious effect on studied mouse models was observed. The impacts of an added inhibitor on a variety of mitochondrial functions were analyzed, such as respiratory activity, mitochondrial bioenergetics, and biogenesis, and a few age-associated comorbidities, including reactive oxygen species (ROS) production, glucose abnormalities, and obesity in mice. It was found that mitochondrial quality, dynamics, and oxidative metabolism were greatly improved, resulting in lean mice with a specific reduction in visceral fat plus superb energy and glucose homeostasis during their aging period compared to the control group. These results strongly suggest that a mild interference in ATP synthesis through moderation of mitochondrial activity could effectively up-regulate mitogenesis, reduce ROS production, and preserve mitochondrial integrity, thereby impeding the onset of metabolic syndrome. We conclude that this inhibitory intervention in mitochondrial respiration rectified the age-related physiological breakdown in mice by protecting mitochondrial function and markedly mitigated certain undesired primary outcomes of metabolic syndrome, such as obesity and type 2 diabetes. This intervention warrants further research on the treatment of metabolic syndrome of aging in humans.

Glutaminase-1 (GLS1) inhibition limits metastatic progression in osteosarcoma

BACKGROUND

Osteosarcoma (OS) is a malignant bone tumor that often develops during the period of rapid growth associated with adolescence. Despite successful primary tumor control accompanied by adjuvant chemotherapy, death from pulmonary metastases occurs in approximately 30% of patients within 5 years. As overall survival in patients remains unchanged over the last 30 years, urgent needs for novel therapeutic strategies exist. Cancer metastasis is characterized by complex molecular events which result from alterations in gene and protein expression/function. Recent studies suggest that metabolic adaptations, or "metabolic reprogramming," may similarly contribute to cancer metastasis. The goal of this study was to specifically interrogate the metabolic vulnerabilities of highly metastatic OS cell lines in a series of in vitro and in vivo experiments, in order to identify a tractable metabolically targeted therapeutic strategy for patients.

METHODS

Nutrient deprivation and drug treatment experiments were performed in MG63.3, 143B, and K7M2 OS cell lines to identify the impact of glutaminase-1 (GLS1) inhibition and metformin treatment on cell proliferation. We functionally validated the impact of drug treatment with extracellular flux analysis, nuclear magnetic resonance (NMR) spectroscopy, and mass spectrometry. 13C-glucose and 13C-glutamine tracing was employed to identify specific contributions of these nutrients to the global metabolic profiles generated with GLS1 inhibition and metformin treatment in vivo.

RESULTS

Highly metastatic OS cell lines require glutamine for proliferation, and exposure to CB-839, in combination with metformin, induces both primary tumor growth inhibition and a distinct reduction in metastatic outgrowth in vivo. Further, combination-treated OS cells showed a reduction in cellular mitochondrial respiration, while NMR confirmed the pharmacodynamic effects of glutaminase inhibition in tumor tissues. We observed global decreases in glycolysis and tricarboxylic acid (TCA) cycle functionality, alongside an increase in fatty acid oxidation and pyrimidine catabolism.

CONCLUSIONS

This data suggests combination-treated cells cannot compensate for metformin-induced electron transport chain inhibition by upregulating glutaminolysis to generate TCA cycle intermediates required for cell proliferation, translating into significant reductions in tumor growth and metastatic progression. This therapeutic approach could be considered for future clinical development for OS patients presenting with or at high risk of developing metastasis.

New drugs are not enough‑drug repositioning in oncology: An update

Drug repositioning refers to the concept of discovering novel clinical benefits of drugs that are already known for use treating other diseases. The advantages of this are that several important drug characteristics are already established (including efficacy, pharmacokinetics, pharmacodynamics and toxicity), making the process of research for a putative drug quicker and less costly. Drug repositioning in oncology has received extensive focus. The present review summarizes the most prominent examples of drug repositioning for the treatment of cancer, taking into consideration their primary use, proposed anticancer mechanisms and current development status.

From old to new - Repurposing drugs to target mitochondrial energy metabolism in cancer

Although we have entered the era of personalized medicine and tailored therapies, drugs that target a large variety of cancers regardless of individual patient differences would be a major advance nonetheless. This review article summarizes current concepts and therapeutic opportunities in the area of targeting aerobic mitochondrial energy metabolism in cancer. Old drugs previously used for diseases other than cancer, such as antibiotics and antidiabetics, have the potential to inhibit the growth of various tumor entities. Many drugs are reported to influence mitochondrial metabolism. However, here we consider only those drugs which predominantly inhibit oxidative phosphorylation.

Dopamine agonist resistant prolactinomas: any alternative medical treatment?

Consensus guidelines recommend dopamine agonists (DAs) as the mainstay treatment for prolactinomas. In most patients, DAs achieve tumor shrinkage and normoprolactinemia at well tolerated doses. However, primary or, less often, secondary resistance to DAs may be also encountered representing challenging clinical scenarios. This is particularly true for aggressive prolactinomas in which surgery and radiotherapy may not achieve tumor control. In these cases, alternative medical treatments have been considered but data on their efficacy should be interpreted within the constraints of publication bias and of lack of relevant clinical trials. The limited reports on somatostatin analogues have shown conflicting results, but cases with optimal outcomes have been documented. Data on estrogen modulators and metformin are scarce and their usefulness remains to be evaluated. In many aggressive lactotroph tumors, temozolomide has demonstrated optimal outcomes, whereas for other cytotoxic agents, tyrosine kinase inhibitors and for inhibitors of mammalian target of rapamycin (mTOR), higher quality evidence is needed. Finally, promising preliminary results from in vitro and animal reports need to be further assessed and, if appropriate, translated in human studies.

Combination of Metformin and Gefitinib as First-Line Therapy for Nondiabetic Advanced NSCLC Patients with EGFR Mutations: A Randomized, Double-Blind Phase II Trial

PURPOSE

Preclinical and retrospective studies suggested a role for metformin in sensitizing patients who have diabetes with non-small cell lung cancer (NSCLC) to EGFR tyrosine kinase inhibitors (TKIs). We therefore examined its effects in combination with gefitinib in patients without diabetes harboring EGFR mutations (EGFRm).

PATIENTS AND METHODS

A total of 224 patients without diabetes with treatment-naïve stage IIIB-IV EGFRm NSCLC were randomly assigned in a 1:1 ratio to receive gefitinib plus either metformin or placebo. The primary endpoint was progression-free survival (PFS) rate at 1 year and secondary endpoints included overall survival (OS), PFS, objective response rate (ORR), and safety. Serum levels of IL6 were also examined in an exploratory analysis.

RESULTS

The median duration of follow-up was 19.15 months. The estimated 1-year PFS rates were 41.2% [95% confidence interval (CI), 30.0-52.2] with gefitinib plus metformin and 42.9% (95% CI, 32.6-52.7) with gefitinib plus placebo (P = 0.6268). Median PFS (10.3 months vs. 11.4 months) and median OS (22.0 months vs. 27.5 months) were numerically lower in the metformin group, while ORRs were similar between the two arms (66% vs. 66.7%). No significant treatment group differences were detected across all subgroups with respect to PFS, including those with elevated levels of IL6. Metformin combined with gefitinib resulted in a remarkably higher incidence of diarrhea compared with the control arm (78.38% vs. 43.24%).

CONCLUSIONS

Our study showed that addition of metformin resulted in nonsignificantly worse outcomes and increased toxicity and hence does not support its concurrent use with first-line EGFR-TKI therapy in patients without diabetes with EGFRm NSCLC.

The role of an anti-diabetic drug metformin in the treatment of endocrine tumors

Incidence of endocrine cancers is rising every year. Over the last decade, evidence has accumulated that demonstrates the anti-cancer effects of an anti-diabetic drug, metformin, in endocrine malignancies. We performed a literature review utilizing the PubMed, Medline and clinicaltrials.gov databases using the keyword 'metformin' plus the following terms: 'thyroid cancer', 'thyroid nodules', 'parathyroid', 'hyperparathyroidism', 'adrenal adenoma', 'Cushing syndrome', 'hyperaldosteronism', 'adrenocortical cancer', 'neuroendocrine tumor (NET)', 'pancreatic NET (pNET)', 'carcinoid', 'pituitary adenoma', 'pituitary neuroendocrine tumor (PitNET)', 'prolactinoma', 'pheochromocytoma/paraganglioma'. We found 37 studies describing the preclinical and clinical role of metformin in endocrine tumors. The available epidemiological data show an association between exposure of metformin and lower incidence of thyroid cancer and pNETs in diabetic patients. Metformin treatment has been associated with better response to cancer therapy in thyroid cancer and pNETs. Preclinical evidence suggests that the primary direct mechanisms of metformin action include inhibition of mitochondrial oxidative phosphorylation via inhibition of both mitochondrial complex I and mitochondrial glycerophosphate dehydrogenase, leading to metabolic stress. Decreased ATP production leads to an activation of a cellular energy sensor, AMPK, and subsequent downregulation of mTOR signaling pathway, which is associated with decreased cellular proliferation. We also describe several AMPK-independent mechanisms of metformin action, as well as the indirect mechanisms targeting insulin resistance. Overall, repositioning of metformin has emerged as a promising strategy for adjuvant therapy of endocrine tumors. The mechanisms of synergy between metformin and other anti-cancer agents need to be elucidated further to guide well-designed prospective trials on combination therapies in endocrine malignancies.

The effect of metformin on biomarkers associated with breast cancer outcomes: a systematic review, meta-analysis, and dose-response of randomized clinical trials

PURPOSE

Breast cancer is a leading cause of cancer mortality in developed countries. We performed a meta-analysis of randomized clinical trials to investigate the effect of metformin on biomarkers associated with breast cancer outcomes and to explore the dose-response relationship.

METHODS

A systematic search was performed from onset of the database to January 2019 in MEDLINE/PubMed, SCOPUS, and Cochrane library to identify randomized clinical trials investigating the impact of metformin on insulin, glucose, CRP, leptin, body mass indices (BMI), cholesterol, Ki-67, and Homeostatic Model Assessment for Insulin-Resistance (HOMA-IR). Effect sizes were expressed as weighted mean difference (WMD) and 95% confidence intervals (CI) using a random-effects models.

RESULTS

Nine studies providing 1,363 participants were included in the meta-analysis. Pooled results showed a significant reduction in insulin (WMD: - 0.99 U/ml, 95% CI - 1.66, - 0.33), glucose (WMD: - 1.78 ml/dl, 95% CI - 2.96, - 0.60), CRP (WMD: - 0.60 mg/l, 95% CI - 0.88, - 0.33), HOMA-IR (WMD: - 0.45, 95% CI - 0.77, - 0.11), leptin (WMD: - 2.44 ng/ml, 95% CI - 3.28, - 1.61), BMI (WMD: - 0.55 kg/m², 95% CI - 1.00, - 0.11), and Ki-67 (WMD: - 4.06, 95% CI - 7.59, - 0.54). Results of the subgroup analyses showed that insulin, glucose, and BMI decreased more significantly when the duration of administering metformin intervention was above 4 weeks. We did not observe non-linear changes in the dose-response relationship between metformin and biomarkers as outcomes.

CONCLUSIONS

Breast cancer patients receiving metformin as treatment for diabetes showed significant reduction in levels of insulin, fasting glucose, CRP, HOMA, leptin, BMI, and Ki-67.

Targeting autophagy enhances the anticancer effect of artemisinin and its derivatives

Artemisinin and its derivatives, with their outstanding clinical efficacy and safety, represent the most effective and impactful antimalarial drugs. Apart from its antimalarial effect, artemisinin has also been shown to exhibit selective anticancer properties against multiple cancer types both in vitro and in vivo. Specifically, our previous studies highlighted the therapeutic effects of artemisinin on autophagy regulation. Autophagy is a well-conserved degradative process that recycles cytoplasmic contents and organelles in lysosomes to maintain cellular homeostasis. The deregulation of autophagy is often observed in cancer cells, where it contributes to tumor adaptation to nutrient-deficient tumor microenvironments. This review discusses recent advances in the anticancer properties of artemisinin and its derivatives via their regulation of autophagy, mitophagy, and ferritinophagy. In particular, we will discuss the mechanisms of artemisinin activation in cancer and novel findings regarding the role of artemisinin in regulating autophagy, which involves changes in multiple signaling pathways. More importantly, with increasing failure rates and the high cost of the development of novel anticancer drugs, the strategy of repurposing traditional therapeutic Chinese medicinal agents such as artemisinin to treat cancer provides a more attractive alternative. We believe that the topics covered here will be important in demonstrating the potential of artemisinin and its derivatives as safe and potent anticancer agents.

Metformin Inhibits the NLRP3 Inflammasome via AMPK/mTOR-dependent Effects in Diabetic Cardiomyopathy

Metformin is a widely used antidiabetic drug for type 2 diabetes that can play a cardioprotective role through multiple pathways. It is a recognized agonist of AMP-activated protein kinase (AMPK) that blocks mitochondrial complex I. The NLRP3 inflammasome has been demonstrated to be activated in diabetic cardiomyopathy (DCM). However, the role of metformin in regulating the NLRP3 signaling pathway in DCM remains unclear. It has been reported that AMPK can inhibit NLRP3 by activating autophagy. The aim of this study was to investigate whether metformin can inhibit the NLRP3 inflammasome by activating the AMPK/mTOR pathway in DCM. In this study, streptozotocin-induced C57BL/6 mice and high glucose-treated primary cardiomyocytes from neonatal mice were treated with metformin or an AMPK inhibitor compound C. Echocardiography, hematoxylin-eosin and Masson staining showed that the function and morphology of the diabetic hearts were improved after metformin treatment, whereas these parameters deteriorated after intervention with an AMPK inhibitor. Immunohistochemical staining, immunofluorescence staining and western blot assays indicated that the expression levels of mTOR, NLRP3, caspase-1, IL-1β and GSDMD-N were decreased in the diabetic model treated with metformin and were reversed after the administration of an AMPK inhibitor in vivo and in vitro. Mechanistically, our results demonstrated that metformin can activate AMPK, thus improving autophagy via inhibiting the mTOR pathway and alleviating pyroptosis in DCM. Thus, we provide novel information for the treatment of DCM.

Global phosphoproteomic analysis reveals ARMC10 as an AMPK substrate that regulates mitochondrial dynamics

AMP-activated protein kinase (AMPK) is a key regulator of cellular energy homeostasis. Although AMPK has been studied extensively in cellular processes, understanding of its substrates and downstream functional network, and their contributions to cell fate and disease development, remains incomplete. To elucidate the AMPK-dependent signaling pathways, we performed global quantitative phosphoproteomic analysis using wild-type and AMPKα1/α2-double knockout cells and discovered 160 AMPK-dependent phosphorylation sites. Further analysis using an AMPK consensus phosphorylation motif indicated that 32 of these sites are likely direct AMPK phosphorylation sites. We validated one uncharacterized protein, ARMC10, and demonstrated that the S45 site of ARMC10 can be phosphorylated by AMPK both in vitro and in vivo. Moreover, ARMC10 overexpression was sufficient to promote mitochondrial fission, whereas ARMC10 knockout prevented AMPK-mediated mitochondrial fission. These results demonstrate that ARMC10 is an effector of AMPK that participates in dynamic regulation of mitochondrial fission and fusion.

AMPK is regulates cellular energy and has been extensively studied, although our knowledge of downstream substrates is incomplete. Here, Chen et al. perform global quantitative analysis for AMPK-dependent sites and validate one hit, ARMC10, as a direct AMPK effector of mitochondrial dynamics.

The Effects of Metformin and Weight Loss on Biomarkers Associated With Breast Cancer Outcomes

Background

This study investigated the effects of metformin and weight loss on biomarkers associated with breast cancer prognosis.

Methods

Overweight/obese postmenopausal breast cancer survivors (n = 333) were randomly assigned to metformin vs placebo and to a weight loss intervention vs control (ie, usual care). The 2 × 2 factorial design allows a single randomized trial to investigate the effect of two factors and interactions between them. Outcomes were changes in fasting insulin, glucose, C-reactive protein (CRP), estradiol, testosterone, and sex-hormone binding globulin (SHBG). The trial was powered for a main effects analysis of metformin vs placebo and weight loss vs control. All tests of statistical significance were two-sided.

Results

A total of 313 women (94.0%) completed the six-month trial. High prescription adherence (ie, ≥80% of pills taken) ranged from 65.9% of participants in the metformin group to 81.3% of those in the placebo group (P < .002). Mean percent weight loss was statistically significantly higher in the weight loss group (-5.5%, 95% confidence interval [CI] = -6.3% to -4.8%) compared with the control group (-2.7%, 95% CI = -3.5% to -1.9%). Statistically significant group differences (ie, percent change in metformin group minus placebo group) were -7.9% (95% CI = -15.0% to -0.8%) for insulin, -10.0% (95% CI = -18.5% to -1.5%) for estradiol, -9.5% (95% CI = -15.2% to -3.8%) for testosterone, and 7.5% (95% CI = 2.4% to 12.6%) for SHBG. Statistically significant group differences (ie, percent change in weight loss group minus placebo group) were -12.5% (95% CI = -19.6% to -5.3%) for insulin and 5.3% (95% CI = 0.2% to 10.4%) for SHBG.

Conclusions

As adjuvant therapy, weight loss and metformin were found to be a safe combination strategy that modestly lowered estrogen levels and advantageously affected other biomarkers thought to be on the pathway for reducing breast cancer recurrence and mortality.

What the oncologist can learn from diabetes studies: Epidemiology, prevention, management, cure

Notwithstanding massive efforts and investment in improving cancer therapy, the limited progress made in reducing overall mortality has mostly been achieved through early diagnosis. Mortality rates for cardiovascular disease are in decline, a success attributable in large part to an active prevention approach coupled with identification of risk factors and biomarkers. Promising natural and synthetic molecules including numerous flavonoids have the potential to be used in diabetes care and in prevention of cardiovascular pathologies. These concepts should also be applied to cancer, the incidence of which continues to increase. In cancer chemoprevention low toxicity drugs or dietary constituents are used to prevent or delay onset of malignancy. Evidence is accumulating that cancer chemoprevention is a valuable weapon against human cancer. For example, doubling of fruit and fiber intake is associated with reduction of colorectal cancer whereas fat food consumption appears to increase malignant progression of certain tumors. Breast, colorectal and prostate cancer are the most suitable cancers for dietary prevention and scientists have strong data in these cancers at basic, translational, clinical and epidemiological levels, due to experimental evidence and the large EPIC study. Physical activity is also crucial. Yet, cancer chemoprevention research in oncology is largely underrepresented and lags far behind the efforts dedicated to therapy; it is important to close this gap. Few European phase III clinical trials are ongoing and systematic development of novel agents for cancer prevention is rare in Europe.

How do cancer cells replenish their fuel supply?

BACKGROUND

Multiple genetic changes, availability of cellular nutrients and metabolic alterations play a pivotal role in oncogenesis AIMS: We focus on cancer cell's metabolic properties, and we outline the cross talks between cellular oncogenic growth pathways in cancer metabolism. The review also provides a synopsis of the relevant cancer drugs targeting metabolic activities that are at various stages of clinical development.

METHODS

We review literature published within the last decade to include select articles that have highlighted energy metabolism crucial to the development of cancer phenotypes.

RESULTS

Cancer cells maintain their potent metabolism and keep a balanced redox status by enhancing glycolysis and autophagy and rerouting Krebs cycle intermediates and products of β-oxydation.

CONCLUSIONS

The processes underlying cancer pathogenesis are extremely complex and remain elusive. The new field of systems biology provides a mathematical framework in which these homeostatic dysregulation principles may be examined for better understanding of cancer phenotypes. Knowledge of key players in cancer-related metabolic reprograming may pave the way for new therapeutic metabolism-targeted drugs and ultimately improve patient care.