Is it still worth pursuing the repurposing of metformin as a cancer therapeutic?

Effects of the number of ethylene glycol units on the efficacy of novel complex I inhibitor 9bw

4'-Iodobiphenyl nonaethylene glycol ether (9bw) is a novel small molecule, composed of a biphenyl unit and 9 ethylene glycol (EG) units. Recently, we found that 9bw induces apoptosis in cancer cells by inhibiting mitochondrial respiratory complex I (CI) and accordingly reducing cellular ATP level. In addition, 9bw shows little effect on normal cells, suggesting that 9bw is a potential antitumor agent with few adverse effects. However, the exact molecular mechanisms by which 9bw acts on CI are still elusive. To clarify the molecular structure critical for 9bw's function, we tested the function of 9bw analogues on human oral squamous cell carcinoma lines HSC4 and Ca9-22. The analogues were 4-hydroxy-4'-iodobiphenyl (HIOP), I-BP-EG3, I-BP-EG6, and I-BP-EG12 containing 0, 3, 6, and 12 EG units, respectively. Our results demonstrated that I-BP-EG6 and I-BP-EG12 inhibited CI to a similar extent as 9bw, whereas I-BP3 and HIOP showed no effect on CI activity. These observations indicate that the number of EG units is crucial for the activity of 9bw and its analogues. As high-performance liquid chromatography (HPLC) analysis demonstrated that both HIOP and I-BP-EG3 could be incorporated into mitochondria abundantly, the number of EG units probably affects CI inhibitory function of 9bw and its analogues rather than their efficacy to enter cell and mitochondria.

A randomized phase II/III study of paclitaxel/carboplatin/metformin versus paclitaxel/carboplatin/placebo as initial therapy for measurable stage III or IVA, stage IVB, or recurrent endometrial cancer: An NRG oncology/GOG study

INTRODUCTION

We evaluated the efficacy of the addition of the anti-diabetic drug metformin to standard-of-care paclitaxel and carboplatin (PC) in patients with advanced and recurrent endometrial cancer (EC).

METHODS

In this phase II/III trial, EC patients with chemotherapy-naïve stage III/IVA (with measurable disease) and stage IVB or recurrent (with or without measurable disease) disease were randomly assigned to PC/metformin (850 mg BID) versus PC/placebo. Metformin or placebo was continued as maintenance therapy after completion of PC until disease progression. The primary endpoint of phase II was progression-free survival (PFS). The primary endpoint of phase III was overall survival (OS). Secondary endpoints were objective response, duration of response, and toxicity.

RESULTS

From 3/17/2014 to 12/22/2017, 448 patients were randomized to phase II/III studies, and the data were frozen for interim analysis. The phase II study deemed metformin worthy of further investigation in the phase III study. The interim phase III analysis stopped accrual for futility on 2/1/2018. The addition of metformin to PC had a slightly higher hazard of death compared to the PC regimen (HR = 1.088; 90% CI 0.803 to 1.475), which was sufficient to close the study early. The PFS had (HR = 0.814; 90% CI 0.635 to 1.043). At a median follow-up of 10 months and 121 deaths, median OS was not determined and 28 months, on PC/placebo and PC/metformin, respectively.

CONCLUSION

The hazard ratios for PFS and OS endpoints was not sufficiently decreased with the addition of metformin to PC to justify continuing the trial.

Metformin-induced E6/E7 inhibition prevents HPV-positive cancer progression through p53 reactivation

The human papillomavirus (HPV) is implicated in multiple lethal cancers, although it is more sensitive to certain therapies than HPV-negative cancers. Therefore, the development of more targeted therapeutic strategies is imperative. The HPV oncogenes E6/E7 are ideal targets for HPV-positive cancer, but there are no clinical strategies that have been proven to effectively target E6/E7. Notably, metformin significantly inhibits E6/E7 expression; however, the underlying mechanism and therapeutic potential remain unclear, limiting its clinical translation. Cell Counting Kit-8, ethynyl-2'-deoxyuridine, and terminal-deoxynucleotidyl transferase-mediated Nick end labeling assays were conducted to evaluate the effects of metformin on cell viability, proliferation, and apoptosis. Quantitative real-time PCR, western blotting, and immunofluorescence assays were performed to determine changes in E6/E7 and p53 expression levels following metformin treatment. Patient-derived organoids and in-vivo xenograft models were constructed to evaluate the anticancer activity of metformin against HPV-positive cancer. Our research demonstrated enhanced sensitivity of HPV-positive cancer cells to metformin. Mechanistic studies have revealed that metformin exerts anticancer effects by inhibiting E6/E7 expression, which is associated with p53 reactivation. Furthermore, we substantiated the anticancer potential of metformin in HPV-positive patient-derived organoids and in-vivo tumor models. Our study focused on the mechanism underlying the enhanced responsiveness of HPV-positive cancer to metformin, highlighting the clinical potential of metformin as a targeted therapeutic strategy for HPV-positive cancer.

Investigation of the synergistic effect of metformin and FX11 on PANC-1 cell lines

BACKGROUND

Pancreatic cancer is among the most aggressive and malignant tumors and is a leading cause of cancer-related mortality. It is characterized by its metabolic Warburg effect and glucose dependence. Aerobic glycolysis is a key feature of metabolic reprogramming in cancer cells. This study investigates the combined effect of metformin and FX11, hypothesizing that disrupting cancer cell energetics through complementary mechanisms may result in a synergistic therapeutic effect. The combination of metformin and FX11 affects the axis that regulates vital functions in cancer cells; thus, the uncontrolled growth of tumor cells, especially those that use a lactose-dependent energy pathway, can be controlled. Several in vitro experiments were conducted to evaluate this hypothesis. PANC-1 cell proliferation was assessed using an MTS assay, lactate levels were measured via an LDH assay, and apoptosis was determined using a flow cytometry-based PE-annexin V assay. The downstream effects of metformin and FX11 treatment were evaluated via western blot analysis.

RESULTS

The findings of this study revealed that metformin and FX11 significantly decreased the viability of PANC-1 cells when used in combination, and this effect was achieved by significantly affecting the energy mechanism of the cells through the AMPKα axis. Furthermore, the lactate levels in PANC1 cells co-treated with metformin and FX11 were significantly decreased, while the increased cellular stress led the cells to apoptosis.

CONCLUSIONS

Compared with metformin treatment alone, the combination treatment of metformin and FX11 stimulates cellular stress in pancreatic cancer and targets various energy processes that encourage cancer cells to undergo apoptosis. This study provides a novel therapeutic strategy for the treatment of pancreatic cancer.

Old drugs, new challenges: reassigning drugs for cancer therapies

The "War on Cancer" began with the National Cancer Act of 1971 and despite more than 50 years of effort and numerous successes, there still remains much more work to be done. The major challenge remains the complexity and intrinsic polygenicity of neoplastic diseases. Furthermore, the safety of the antitumor therapies still remains a concern given their often off-target effects. Although the amount of money invested in research and development required to introduce a novel FDA-approved drug has continuously increased, the likelihood for a new cancer drug's approval remains limited. One interesting alternative approach, however, is the idea of repurposing of old drugs, which is both faster and less costly than developing new drugs. Repurposed drugs have the potential to address the shortage of new drugs with the added benefit that the safety concerns are already established. That being said, their interactions with other new drugs in combination therapies, however, should be tested. In this review, we discuss the history of repurposed drugs, some successes and failures, as well as the multiple challenges and obstacles that need to be addressed in order to enhance repurposed drugs' potential for new cancer therapies.

Rethinking AMPK: A Reversible Switch Fortifying Cancer Cell Stress-Resilience

Stress adaptation is an evolutionarily conserved mechanism that promotes survival in the face of adverse conditions. AMP-activated protein kinase (AMPK) is a highly conserved energy-sensing kinase found in nearly all eukaryotic cells. It maintains energy homeostasis by promoting catabolism and inhibiting anabolism. In the context of cancer, the role of AMPK is controversial. It was initially touted as a tumor suppressor due to its association with Liver Kinase B1 (LKB1) (an upstream regulator and a known tumor suppressor) and ensuing growth-suppressive actions. However, emerging studies across a variety of cancer types unambiguously reveal AMPK's pro-survival and, thus, tumor-promoting activity, especially under cancer-associated stresses such as hypoxia, nutrient deprivation, oxidative stress, matrix detachment, and chemotherapy. In cancer cells, AMPK is activated in response to stress-induced increases in the levels of adenosine monophosphate (AMP), Ca2+, or reactive oxygen species (ROS). Upon activation, AMPK engages in metabolic rewiring and crosstalk with signaling molecules to mobilize resources toward survival while compromising proliferation. Here, we posit that AMPK is a non-genetic "reversible switch," allowing cancer cells' phenotype to switch to dormant, stem-like, and drug-resistant states, thereby enabling tumor cell survival, pathological progression, and therapy resistance. This review underscores the critical role of AMPK in driving cancer cell stress resilience and survival, advocating for the strategic use of AMPK inhibitors to improve cancer treatment outcomes.

Olaparib combined to metronomic cyclophosphamide and metformin in women with recurrent advanced/metastatic endometrial cancer: the ENDOLA phase I/II trial

Endometrial cancers are characterized by frequent alterations in the PI3K-AKT-mTor, IGF1 and DNA repair signaling pathways. Concomitant inhibition of these pathways was warranted. ENDOLA phase I/II trial (NCT02755844) was designed to assess the safety/efficacy of the triplet combination of the PARP inhibitor olaparib, metronomic cyclophosphamide (50 mg daily), and PI3K-AKT-mTor inhibitor metformin (1500 mg daily) in women with recurrent endometrial carcinomas. Olaparib dose-escalation (100-300 mg twice-a-day (bid)) was used to determine the recommended-phase II-trial-dose (RP2D, primary endpoint), followed by an expansion cohort to determine the non-progression rate at 10 weeks (NPR-10w, secondary endpoint). 31 patients were treated. Olaparib RP2D was defined as 300 mg bid. The tolerability was acceptable, and grade 3-4 adverse events (51% patients) were mainly hematological. The NPR-10w was 61.5%, and the median progression-free survival (mPFS) was 5.2 months. In a post-hoc analysis, when explored by molecular subtypes/alterations, longer PFS were observed in patients with tumors characterized by a non-specific-molecular-profile (NSMP, n = 4; mPFS, 9.1 months), and by both TP53 altered & high number of large genomic alterations (LGA ≥ 8)(n = 10, mPFS, 8.6 months)). The analyses about kinetics of circulating biomarkers and pharmacodynamic effects are not reported here. In total, the benefit/toxicity ratio of the all-oral olaparib/cyclophosphamide/metformin regimen was favorable in heavily pretreated patients with recurrent endometrial cancer.

Metformin inhibits the growth of SCLC cells by inducing autophagy and apoptosis via the suppression of EGFR and AKT signalling

Small cell lung cancer (SCLC) is a therapeutically challenging disease. Metformin, an effective agent for the treatment of type 2 diabetes, has been shown to have antitumour effects on many cancers, including non-small cell lung cancer (NSCLC) and breast cancer. Currently, the antitumour effects of metformin on SCLC and the underlying molecular mechanisms remain unclear. CCK-8, EdU, colony formation, flow cytometry, immunofluorescence, molecular docking, western blotting, nude mouse transplanted tumour model, and immunohistochemistry experiments were conducted to analyse gene functions and the underlying mechanism involved. In vitro experiments demonstrated that metformin inhibited the growth of SCLC cells (H446, H526, H446/DDP and H526/DDP), which was confirmed in xenograft mouse models in vivo. Additionally, metformin induced cell cycle arrest, apoptosis, and autophagy in these SCLC cells. The molecular docking results indicated that metformin has a certain binding affinity for EGFR. The western blotting results revealed that metformin decreased the expression of EGFR, p-EGFR, AKT, and p-AKT, which could be reversed by EGF and SC79. Moreover, metformin activated AMPK and inactivated mTOR, and compound C and SC79 increased the levels of p-mTOR. Metformin can not only enhance the antitumour effect of cisplatin but also alleviate the toxic effects of cisplatin on the organs of xenograft model animals. In summary, the current study revealed that metformin inhibits the growth of SCLC by inducing autophagy and apoptosis via suppression of the EGFR/AKT/AMPK/mTOR pathway. Metformin might be a promising candidate drug for combination therapy of SCLC.

Metabolic crossroads: unravelling immune cell dynamics in gastrointestinal cancer drug resistance

Metabolic reprogramming within the tumor microenvironment (TME) plays a critical role in driving drug resistance in gastrointestinal cancers (GI), particularly through the pathways of fatty acid oxidation and glycolysis. Cancer cells often rewire their metabolism to sustain growth and reshape the TME, creating conditions such as nutrient depletion, hypoxia, and acidity that impair antitumor immune responses. Immune cells within the TME also undergo metabolic alterations, frequently adopting immunosuppressive phenotypes that promote tumor progression and reduce the efficacy of therapies. The competition for essential nutrients, particularly glucose, between cancer and immune cells compromises the antitumor functions of effector immune cells, such as T cells. Additionally, metabolic by-products like lactate and kynurenine further suppress immune activity and promote immunosuppressive populations, including regulatory T cells and M2 macrophages. Targeting metabolic pathways such as fatty acid oxidation and glycolysis presents new opportunities to overcome drug resistance and improve therapeutic outcomes in GI cancers. Modulating these key pathways has the potential to reinvigorate exhausted immune cells, shift immunosuppressive cells toward antitumor phenotypes, and enhance the effectiveness of immunotherapies and other treatments. Future strategies will require continued research into TME metabolism, the development of novel metabolic inhibitors, and clinical trials evaluating combination therapies. Identifying and validating metabolic biomarkers will also be crucial for patient stratification and treatment monitoring. Insights into metabolic reprogramming in GI cancers may have broader implications across multiple cancer types, offering new avenues for improving cancer treatment.

Modification in Structures of Active Compounds in Anticancer Mitochondria-Targeted Therapy

Cancer is a multifaceted disease characterised by uncontrolled cellular proliferation and metastasis, resulting in significant global mortality. Current therapeutic strategies, including surgery, chemotherapy, and radiation therapy, face challenges such as systemic toxicity and tumour resistance. Recent advancements have shifted towards targeted therapies that act selectively on molecular structures within cancer cells, reducing off-target effects. Mitochondria have emerged as pivotal targets in this approach, given their roles in metabolic reprogramming, retrograde signalling, and oxidative stress, all of which drive the malignant phenotype. Targeting mitochondria offers a promising strategy to address these mechanisms at their origin. Synthetic derivatives of natural compounds hold particular promise in mitochondrial-targeted therapies. Innovations in drug design, including the use of conjugates and nanotechnology, focus on optimizing these compounds for mitochondrial specificity. Such advancements enhance therapeutic efficacy while minimizing systemic toxicity, presenting a significant step forward in modern anticancer strategies.

The future of metronomic chemotherapy: experimental and computational approaches of drug repurposing

Metronomic chemotherapy (MC), long-term continuous administration of anticancer drugs, is gaining attention as an alternative to the traditional maximum tolerated dose (MTD) chemotherapy. By combining MC with other treatments, the therapeutic efficacy is enhanced while minimizing toxicity. MC employs multiple mechanisms, making it a versatile approach against various cancers. However, drug resistance limits the long-term effectiveness of MC, necessitating ongoing development of anticancer drugs. Traditional drug discovery is lengthy and costly due to processes like target protein identification, virtual screening, lead optimization, and safety and efficacy evaluations. Drug repurposing (DR), which screens FDA-approved drugs for new uses, is emerging as a cost-effective alternative. Both experimental and computational methods, such as protein binding assays, in vitro cytotoxicity tests, structure-based screening, and several types of association analyses (Similarity-Based, Network-Based, and Target Gene), along with retrospective clinical analyses, are employed for virtual screening. This review covers the mechanisms of MC, its application in various cancers, DR strategies, examples of repurposed drugs, and the associated challenges and future directions.

Carbohydrate kinase inhibition: a promising strategy in cancer treatment

Carbohydrate kinases (CKs) are pivotal in various biological processes, including energy consumption, cell signaling, and biosynthesis. They are a group of enzymes that facilitate the phosphorylation of carbohydrates, playing a crucial role in cellular metabolism. These enzymes facilitate the transfer of a phosphate group from a high-energy donor like ATP to a specified location on a carbohydrate substrate. Dysregulated kinase activity drives tumor growth and progression. Inhibitors targeting these enzymes have been developed and used in cancer therapy. The CK family encompasses three major types: hexokinases, ribokinases, and phosphatidylinositol kinases, with inhibitors of paramount importance in cancer treatment. This review explores the role of CKs in cancer and its inhibitors, providing insights into improving existing inhibitors and designing new ones.

Dietary Restrictions and Cancer Prevention: State of the Art

Worldwide, almost 10 million cancer deaths occurred in 2022, a number that is expected to rise to 16.3 million by 2040. Primary prevention has long been acknowledged as a crucial approach to reducing cancer incidence. In fact, between 30 and 50 percent of all tumors are known to be preventable by eating a healthy diet, staying active, avoiding alcohol, smoking, and being overweight. Accordingly, many international organizations have created tumor prevention guidelines, which underlie the importance of following a diet that emphasizes eating plant-based foods while minimizing the consumption of red/processed meat, sugars, processed foods, and alcohol. However, further research is needed to define the relationship between the effect of specific diets or nutritional components on cancer prevention. Interestingly, reductions in food intake and dietetic restrictions can extend the lifespan of yeast, nematodes, flies, and rodents. Despite controversial results in humans, those approaches have the potential to ameliorate health via direct and indirect effects on specific signaling pathways involved in cancer onset. Here, we describe the latest knowledge on the cancer-preventive potential of dietary restrictions and the biochemical processes involved. Molecular, preclinical, and clinical studies evaluating the effects of different fasting strategies will also be reviewed.

Metformin for Treating Gestational Diabetes: What Have We Learned During the Last Two Decades? A Systematic Review

There has been accumulating evidence over the past two decades that metformin can be an effective treatment for gestational diabetes mellitus (GDM) in women whose diet and exercise fail to attain optimal glycemic control. The objective of this review was to comprehensively analyze all studies investigating the effectiveness of metformin compared to insulin and other drugs utilized for the treatment of GDM. After a comprehensive literature review based on PRISMA 2020, 35 studies were included after a selection process utilizing predetermined inclusion and exclusion criteria. A variety of short-term maternal and neonatal outcomes were assessed. Metformin is a highly efficient medication for attaining optimal control of blood sugar levels in women with GDM, resulting in a significant reduction in the amount of weight gained during pregnancy. Regarding additional maternal outcomes, such as pregnancy-induced hypertension and cesarean deliveries, some studies demonstrate a link between metformin and a reduced occurrence of both conditions. In contrast, others do not find an association. Regarding short-term neonatal outcomes, metformin does not exhibit any changes in gestational age at delivery. In contrast, metformin demonstrated substantial decreases in the likelihood of greater gestational birth weight and neonatal hospitalization when compared to other drugs. When compared primarily to insulin, metformin decreases the probability of several short-term outcomes related to pregnancy and newborns. Additional data are necessary for extended follow-up studies, including patients with GDM treated with metformin.

Enhancing Radiation Therapy Response in Prostate Cancer Through Metabolic Modulation by Mito-Lonidamine: A 1H and 31P Magnetic Resonance Spectroscopy Study

Radiation therapy (RT) is the cornerstone treatment for prostate cancer; however, it frequently induces gastrointestinal and genitourinary toxicities that substantially diminish the patients' quality of life. While many individuals experience transient side effects, a subset endures persistent, long-term complications. A promising strategy to mitigate these toxicities involves enhancing tumor radiosensitivity, potentially allowing for lower radiation doses. In this context, mito-lonidamine (Mito-LND), an antineoplastic agent targeting the mitochondrial electron transport chain's complexes I and II, emerges as a potential radiosensitizer. This study investigated Mito-LND's capacity to augment RT efficacy and reduce adverse effects through comprehensive in vitro and in vivo assessments using hormone-sensitive and hormone-refractory prostate cancer models. Employing a Seahorse analysis and 1H/31P magnetic resonance spectroscopy (MRS), we observed that Mito-LND selectively suppressed lactate production, decreased intracellular pH, and reduced bioenergetics and oxygen consumption levels within tumor cells. These findings suggest that Mito-LND remodels the tumor microenvironment by inducing acidification, metabolic de-energization, and enhanced oxygenation, thereby sensitizing tumors to RT. Our results underscore the potential of Mito-LND as a therapeutic adjunct in RT to improve patient outcomes and reduce radiation-associated toxicities in early-stage prostate cancer.

Associations between cardiometabolic comorbidities and mortality in adults with cancer: multinational cohort study

ABSTRACT

Objective

To examine separate and joint associations between pre-existing cardiometabolic comorbidities and all cause and cause specific mortality in adults with cancer.

Design

Multinational cohort study.

Setting

Seven European countries from the European Prospective Investigation into Cancer and Nutrition (EPIC) study, 1 January 1992 to 31 December 2013.

Participants

26 987 participants (54% women) who developed a first primary cancer. 2113 had a history of type 2 diabetes, 1529 had a history of cardiovascular disease, and 531 had a history of both, at the time of diagnosis of cancer.

Main outcome measures

Hazard ratios (95% confidence intervals, CIs) for associations between pre-existing cardiometabolic comorbidities and all cause and cause specific mortality in adults with cancer, estimated with multivariable Cox regression models. Associations were also estimated by groups of five year relative survival of cancer (survival ≤40%, 40-80%, and ≥80%) according to Surveillance, Epidemiology, and End Results (SEER) statistics, and for the most common site specific cancers.

Results

At the time of diagnosis of cancer, 84.5% (n=22 814) of participants had no history of a cardiometabolic disease, 7.8% (n=2113) had a history of type 2 diabetes, 5.7% (n=1529) had a history of cardiovascular disease, and 2.0% (n=531) had a history of both cardiovascular disease and type 2 diabetes. 12 782 deaths (10 492 cancer deaths) occurred over a mean follow-up period of 7.2 years. After multivariable adjustments, pre-existing comorbidities were positively associated with all cause mortality, with hazard ratios 1.25 (95% CI 1.17 to 1.34), 1.30 (1.21 to 1.39), and 1.60 (1.42 to 1.80) for participants with type 2 diabetes, cardiovascular disease, or both, respectively, compared with participants with no cardiometabolic comorbidity. Corresponding hazard ratios for cancer specific mortality were 1.13 (95% CI 1.05 to 1.22), 1.13 (1.04 to 1.23), and 1.33 (1.16 to 1.53), respectively. Associations for all cause mortality were stronger among participants with cancers with a five year relative survival ≥80%. In a subsample, duration of type 2 diabetes (Pinteraction=0.73) or cardiovascular disease (Pinteraction=0.24), categorised as <5 years or ≥5 years, did not modify associations between these comorbidities and all cause mortality.

Conclusions

In this study, cardiovascular disease or type 2 diabetes, or a combination of both, before a diagnosis of cancer, was associated with increased mortality (all cause mortality, and cancer and cardiovascular disease specific mortality). These findings support a direct role of cardiometabolic comorbidities on the prognosis of cancer.

Risk of Incident Cancer in Veterans with Diabetes Who Use Metformin Versus Sulfonylureas

Prior research suggests metformin has anti-cancer effects, yet data are limited. We examined the association between diabetes treatment (metformin versus sulfonylurea) and risk of incident diabetes-related and non- diabetes-related cancers in US veterans. This retrospective cohort study included US veterans, without cancer, aged ≥ 55 years, who were new users of metformin or sulfonylureas for diabetes between 2001 to 2012. Cox proportional hazards models, with propensity score-matched inverse probability of treatment weighting (IPTW) were constructed. A total of 88,713 veterans (mean age 68.6 ± 7.8 years; 97.7% male; 84.1% White, 12.6% Black, 3.3% other race) were followed for 4.2 ± 3.0 years. Among metformin users (n = 60,476), there were 858 incident diabetes-related cancers (crude incidence rate [IR; per 1,000 person-years] = 3.4) and 3,533 non-diabetes-related cancers (IR = 14.1). Among sulfonylurea users (n = 28,237), there were 675 incident diabetes-related cancers (IR = 5.5) and 2,316 non-diabetes-related cancers (IR = 18.9). After IPTW adjustment, metformin use was associated with a lower risk of incident diabetes-related cancer (hazard ratio [HR] = 0.66, 95% CI 0.58-0.75) compared to sulfonylurea use. There was no association between treatment group (metformin versus sulfonylurea) and non-diabetes-related cancer (HR = 0.96, 95% CI 0.89-1.02). Of diabetes-related cancers, metformin users had lower incidence of liver (HR = 0.39, 95% CI 0.28-0.53), colorectal (HR = 0.75, 95% CI 0.62-0.92), and esophageal cancers (HR = 0.54, 95% CI 0.36-0.81). Among US veterans, metformin users had lower incidence of diabetes-related cancer, particularly liver, colorectal, and esophageal cancers, as compared to sulfonylurea users. Use of metformin was not associated with non-diabetes-related cancer. Further studies are needed to understand how metformin use impacts cancer incidence in different patient populations.

Metformin targets mitochondrial complex I to lower blood glucose levels

Metformin is among the most prescribed antidiabetic drugs, but the primary molecular mechanism by which metformin lowers blood glucose levels is unknown. Previous studies have proposed numerous mechanisms by which acute metformin lowers blood glucose, including the inhibition of mitochondrial complex I of the electron transport chain (ETC). Here, we used transgenic mice that globally express the Saccharomyces cerevisiae internal alternative NADH dehydrogenase (NDI1) protein to determine whether the glucose-lowering effect of acute oral administration of metformin requires inhibition of mitochondrial complex I of the ETC in vivo. NDI1 is a yeast NADH dehydrogenase enzyme that complements the loss of mammalian mitochondrial complex I electron transport function and is insensitive to pharmacologic mitochondrial complex I inhibitors including metformin. We demonstrate that NDI1 expression attenuates metformin's ability to lower blood glucose levels under standard chow and high-fat diet conditions. Our results indicate that acute oral administration of metformin targets mitochondrial complex I to lower blood glucose.

Comprehensive review of drug resistance in mammalian cancer stem cells: implications for cancer therapy

Cancer remains a significant global challenge, and despite the numerous strategies developed to advance cancer therapy, an effective cure for metastatic cancer remains elusive. A major hurdle in treatment success is the ability of cancer cells, particularly cancer stem cells (CSCs), to resist therapy. These CSCs possess unique abilities, including self-renewal, differentiation, and repair, which drive tumor progression and chemotherapy resistance. The resilience of CSCs is linked to certain signaling pathways. Tumors with pathway-dependent CSCs often develop genetic resistance, whereas those with pathway-independent CSCs undergo epigenetic changes that affect gene regulation. CSCs can evade cytotoxic drugs, radiation, and apoptosis by increasing drug efflux transporter activity and activating survival mechanisms. Future research should prioritize the identification of new biomarkers and signaling molecules to better understand drug resistance. The use of cutting-edge approaches, such as bioinformatics, genomics, proteomics, and nanotechnology, offers potential solutions to this challenge. Key strategies include developing targeted therapies, employing nanocarriers for precise drug delivery, and focusing on CSC-targeted pathways such as the Wnt, Notch, and Hedgehog pathways. Additionally, investigating multitarget inhibitors, immunotherapy, and nanodrug delivery systems is critical for overcoming drug resistance in cancer cells.

Oncogenic HRAS Induces Metformin Resistance in Head and Neck Cancer by Promoting Glycolytic Metabolism

Metformin administration has recently emerged as a candidate strategy for the prevention of head and neck squamous cell carcinoma (HNSCC). However, the intricate relationship between genetic alterations in HNSCC and metformin sensitivity is still poorly understood, which prevents the stratification of patients, harboring oral premalignant lesions that may benefit from the chemopreventive activity of metformin. In this study, we investigate the impact of prevalent mutations in HNSCC on response to metformin. Notably, we found that the expression of oncogenic HRAS mutants confers resistance to metformin in isogenic HNSCC cell systems, and that HNSCC cells harboring endogenous HRAS mutations display limited sensitivity to metformin. Remarkably, we found that metformin fails to reduce activation of the mTOR pathway in HRAS oncogene-expressing HNSCC cells in vitro and in vivo, correlating with reduced tumor suppressive activity. Mechanistically, we found that this process depends on the ability of HRAS to enhance glycolytic metabolism, thereby suppressing the requirement for oxidative phosphorylation to maintain the cellular energetic balance. Overall, our study revealed that HNSCC cells with oncogenic HRAS mutations exhibit diminished metformin sensitivity, thus shedding light on a potential mechanism of treatment resistance. This finding may also help explain the limited clinical responses to metformin in cancers with RAS mutations. Ultimately, our study underscores the importance of understanding the impact of the genetic landscape in tailoring precision cancer-preventive approaches in the context of HNSCC and other cancers that are characterized by the presence of a defined premalignant state, and therefore, are amenable to cancer interception strategies. Prevention Relevance: Our findings highlight the challenges of using metformin for cancer prevention in RAS-mutant cancers, where elevated glycolysis may reduce drug efficacy. This underscores the need to explore metformin's potential in early, premalignant stages, before metabolic shifts render it less effective.

Implications of obesity and insulin resistance for the treatment of oestrogen receptor-positive breast cancer

Breast cancer is the most common cancer in women, and incidence rates are rising, it is thought in part, due to increasing levels of obesity. Endocrine therapy (ET) remains the cornerstone of systemic therapy for early and advanced oestrogen receptor-positive (ER + ) breast cancer, but despite treatment advances, it is becoming more evident that obesity and insulin resistance are associated with worse outcomes. Here, we describe the current understanding of the relationship between both obesity and diabetes and the prevalence and outcomes for ER+ breast cancer. We also discuss the mechanisms associated with resistance to ET and the relationship to treatment toxicity.

Drug Repurposing for Cancer Treatment: A Comprehensive Review

Cancer ranks among the primary contributors to global mortality. In 2022, the global incidence of new cancer cases reached about 20 million, while the number of cancer-related fatalities reached 9.7 million. In Saudi Arabia, there were 13,399 deaths caused by cancer and 28,113 newly diagnosed cases of cancer. Drug repurposing is a drug discovery strategy that has gained special attention and implementation to enhance the process of drug development due to its time- and money-saving effect. It involves repositioning existing medications to new clinical applications. Cancer treatment is a therapeutic area where drug repurposing has shown the most prominent impact. This review presents a compilation of medications that have been repurposed for the treatment of various types of cancers. It describes the initial therapeutic and pharmacological classes of the repurposed drugs and their new applications and mechanisms of action in cancer treatment. The review reports on drugs from various pharmacological classes that have been successfully repurposed for cancer treatment, including approved ones and those in clinical trials and preclinical development. It stratifies drugs based on their anticancer repurpose as multi-type, type-specific, and mechanism-directed, and according to their pharmacological classes. The review also reflects on the future potential that drug repurposing has in the clinical development of novel anticancer therapies.

An anti-neoplastic tale of metformin through its transport

Metformin is an attractive candidate drug among all the repurposed drugs for cancer. Extensive preclinical and clinical research has evaluated its efficacy in cancer therapy, revealing a mixed outcome in clinical settings. To fully exploit metformin's therapeutic potential, understanding cellular factors relevant to its transport and accumulation in cancer cells needs to be understood. This review highlights the relevance of metformin transporter status towards its anti-cancer potential. Metformin transporters are regulated at pre-transcriptional, transcriptional, and post-translational levels. Moreover, the tumour microenvironment can also influence metformin accumulation in cancer cells. Also, Metformin treatment can regulate its transporters by altering global DNA methylation, protein acetylation, and transcription factors. Importantly, metformin transporters not only influence chemotherapeutic drug toxicity but are also associated with the prognosis and survival of individuals having cancer. Strategic decisions based on the expression and regulation of metformin transporters holds promise for its therapeutic implications and relevance.

Shared genetics between breast cancer and predisposing diseases identifies novel breast cancer treatment candidates

BACKGROUND

Current effective breast cancer treatment options have severe side effects, highlighting a need for new therapies. Drug repurposing can accelerate improvements to care, as FDA-approved drugs have known safety and pharmacological profiles. Some drugs for other conditions, such as metformin, an antidiabetic, have been tested in clinical trials for repurposing for breast cancer. Here, we exploit the genetics of breast cancer and linked predisposing diseases to propose novel drug repurposing opportunities. We hypothesize that if a predisposing disease contributes to breast cancer pathology, identifying the pleiotropic genes related to the risk of cancer could prioritize drugs, among all drugs treating a predisposing disease. We aim to develop a method to not only prioritize drugs for repurposing, but also to highlight shared etiology explaining repurposing.

METHODS

We compile breast cancer's predisposing diseases from literature. For each predisposing disease, we use GWAS summary statistics data to identify genes in loci showing genetic correlation with breast cancer. Then, we use a network approach to link these shared genes to canonical pathways. Similarly, for all drugs treating the predisposing disease, we link their targets to pathways. In this manner, we are able to prioritize a list of drugs based on each predisposing disease, with each drug linked to a set of implicating pathways. Finally, we evaluate our recommendations against drugs currently under investigation for breast cancer.

RESULTS

We identify 84 loci harboring mutations with positively correlated effects between breast cancer and its predisposing diseases; these contain 194 identified shared genes. Out of the 112 drugs indicated for the predisposing diseases, 74 drugs can be linked to shared genes via pathways (candidate drugs for repurposing). Fifteen out of these candidate drugs are already in advanced clinical trial phases or approved for breast cancer (OR = 9.28, p = 7.99e-03, one-sided Fisher's exact test), highlighting the ability of our approach to identify likely successful candidate drugs for repurposing.

CONCLUSIONS

Our novel approach accelerates drug repurposing for breast cancer by leveraging shared genetics with its known predisposing diseases. The result provides 59 novel candidate drugs alongside biological insights supporting each recommendation.

Non-coding RNAs as potential targets in metformin therapy for cancer

Metformin, a widely used oral hypoglycemic drug, has emerged as a potential therapeutic agent for cancer treatment. While initially known for its role in managing diabetes, accumulating evidence suggests that metformin exhibits anticancer properties through various mechanisms. Several cellular or animal experiments have attempted to elucidate the role of non-coding RNA molecules, including microRNAs and long non-coding RNAs, in mediating the anticancer effects of metformin. The present review summarized the current understanding of the mechanisms by which non-coding RNAs modulate the response to metformin in cancer cells. The regulatory roles of non-coding RNAs, particularly miRNAs, in key cellular processes such as cell proliferation, cell death, angiogenesis, metabolism and epigenetics, and how metformin affects these processes are discussed. This review also highlights the role of lncRNAs in cancer types such as lung adenocarcinoma, breast cancer, and renal cancer, and points out the need for further exploration of the mechanisms by which metformin regulates lncRNAs. In addition, the present review explores the potential advantages of metformin-based therapies over direct delivery of ncRNAs, and this review highlights the mechanisms of non-coding RNA regulation when metformin is combined with other therapies. Overall, the present review provides insights into the molecular mechanisms underlying the anticancer effects of metformin mediated by non-coding RNAs, offering novel opportunities for the development of personalized treatment strategies in cancer patients.

Overview of the role of purinergic signaling and insights into its role in cancer therapy

Innovation of cancer therapy has received a dramatic acceleration over the last fifteen years thanks to the introduction of the novel immune checkpoint inhibitors (ICI). On the other hand, the conspicuous scientific knowledge accumulated in purinergic signaling since the early seventies is finally being transferred to the clinic. Several Phase I/II clinical trials are currently underway to investigate the effect of drugs interfering with purinergic signaling as stand-alone or combination therapy in cancer. This is supporting the novel concept of "purinergic immune checkpoint" (PIC) in cancer therapy. In the present review we will address a) the basic pharmacology and cell biology of the purinergic system; b) principles of its pathophysiology in human diseases; c) implications for cell death, cell proliferation and cancer; d) novel molecular tools to investigate nucleotide homeostasis in the extracellular environment; e) recent developments in the pharmacology of P1, P2 receptors and related ecto-enzymes; f) P1 and P2 ligands as novel diagnostic tools; g) current issues in PIC-based anti-cancer therapy. This review will provide an appraisal of the current status of purinergic signaling in cancer and will help identify future avenues of development.

Repurposing metabolic regulators: antidiabetic drugs as anticancer agents

Drug repurposing in cancer taps into the capabilities of existing drugs, initially designed for other ailments, as potential cancer treatments. It offers several advantages over traditional drug discovery, including reduced costs, reduced development timelines, and a lower risk of adverse effects. However, not all drug classes align seamlessly with a patient's condition or long-term usage. Hence, repurposing of chronically used drugs presents a more attractive option. On the other hand, metabolic reprogramming being an important hallmark of cancer paves the metabolic regulators as possible cancer therapeutics. This review emphasizes the importance and offers current insights into the repurposing of antidiabetic drugs, including metformin, sulfonylureas, sodium-glucose cotransporter 2 (SGLT2) inhibitors, dipeptidyl peptidase 4 (DPP-4) inhibitors, glucagon-like peptide-1 receptor agonists (GLP-1RAs), thiazolidinediones (TZD), and α-glucosidase inhibitors, against various types of cancers. Antidiabetic drugs, regulating metabolic pathways have gained considerable attention in cancer research. The literature reveals a complex relationship between antidiabetic drugs and cancer risk. Among the antidiabetic drugs, metformin may possess anti-cancer properties, potentially reducing cancer cell proliferation, inducing apoptosis, and enhancing cancer cell sensitivity to chemotherapy. However, other antidiabetic drugs have revealed heterogeneous responses. Sulfonylureas and TZDs have not demonstrated consistent anti-cancer activity, while SGLT2 inhibitors and DPP-4 inhibitors have shown some potential benefits. GLP-1RAs have raised concerns due to possible associations with an increased risk of certain cancers. This review highlights that further research is warranted to elucidate the mechanisms underlying the potential anti-cancer effects of these drugs and to establish their efficacy and safety in clinical settings.

Mechanistic Insights on Metformin and Arginine Implementation as Repurposed Drugs in Glioblastoma Treatment

As the most common and aggressive primary malignant brain tumor, glioblastoma is still lacking a satisfactory curative approach. The standard management consisting of gross total resection followed by radiotherapy and chemotherapy with temozolomide only prolongs patients' life moderately. In recent years, many therapeutics have failed to give a breakthrough in GBM treatment. In the search for new treatment solutions, we became interested in the repurposing of existing medicines, which have established safety profiles. We focused on the possible implementation of well-known drugs, metformin, and arginine. Metformin is widely used in diabetes treatment, but arginine is mainly a cardiovascular protective drug. We evaluated the effects of metformin and arginine on total DNA methylation, as well as the oxidative stress evoked by treatment with those agents. In glioblastoma cell lines, a decrease in 5-methylcytosine contents was observed with increasing drug concentration. When combined with temozolomide, both guanidines parallelly increased DNA methylation and decreased 8-oxo-deoxyguanosine contents. These effects can be explained by specific interactions of the guanidine group with m5CpG dinucleotide. We showed that metformin and arginine act on the epigenetic level, influencing the foreground and potent DNA regulatory mechanisms. Therefore, they can be used separately or in combination with temozolomide, in various stages of disease, depending on desired treatment effects.

Metformin use and risk of myeloproliferative neoplasms: a Danish population-based case-control study

ABSTRACT

Previous studies have suggested that metformin has beneficial effects beyond its glucose-lowering properties, particularly in terms of its potential as an antineoplastic and cancer-preventive agent. In this study, we aimed to investigate the association between metformin use and the risk of myeloproliferative neoplasms (MPN). We conducted a population-based case-control study using Danish registers. Cases with MPN diagnosed between 2010 and 2018 were identified, and metformin use before the MPN diagnosis was ascertained. We compared metformin use among cases with MPN and an age- and sex-matched control group from the Danish general population to estimate age- and sex-adjusted odds ratios (ORs) and fully adjusted ORs (aORs) for the association between metformin use and risk of MPN. The study population included 3816 cases and 19 080 controls. Overall, 7.0% of cases and 8.2% of controls were categorized as ever-users of metformin, resulting in an OR for MPN of 0.84 (95% confidence interval [CI], 0.73-0.96) and an aOR of 0.70 (95% CI, 0.61-0.81). Long-term metformin use (≥5 years) was more infrequent and comprised 1.1% of cases and 2.0% of controls, resulting in an OR of 0.57 (95% CI, 0.42-0.79) and an aOR of 0.45 (95% CI, 0.33-0.63). A dose-response relationship was observed when cumulative duration of treatment was analyzed, and this was consistent in stratified analyses of sex, age, and MPN subtypes. In conclusion, metformin use was associated with significantly lower odds of an MPN diagnosis, indicating its potential cancer-preventive effect. Given the retrospective design, causality cannot be inferred.

Intravenous injectable metformin-Cu(II)-EGCG coordination polymer nanoparticles for electrothermally enhanced dual-drug synergistic tumor therapy

Intravenous injectable metformin-Cu(II)-EGCG infinite coordination polymer nanoparticles (metformin-Cu(II)-EGCG ICP NPs) have been synthesized, and an efficient strategy for synergistic tumor therapy by utilizing these nanoparticles in conjunction with micro-electrothermal needles (MENs) was proposed. These nanoparticles display exceptional uniformity with a diameter of 117.5 ± 53.3 nm, exhibit an extraordinary drug loading capacity of 90% and allow for precise control over the drug ratio within the range of 1 : 1 to 1 : 20 while maintaining excellent thermal stability. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction were employed to determine their chemical structure and coordination state. The combination index (CI) value of the metformin-Cu(II)-EGCG ICP NPs was calculated to be 0.19, surpassing that of the two individual drugs and metformin mixed with EGCG (0.98). Importantly, upon intravenous injection, metformin in nanoparticles demonstrated exceptional stability in the bloodstream, while both drugs were rapidly released within the acidic tumor microenvironment. Animal experiments showcased an impressive tumor inhibition rate of 100% within a mere 20-day time frame after the synergistic therapy with a lower dosage (5.0 mg kg-1 of nanoparticles), coupled with a minimal tumor recurrence rate of only 18.75% over a 60-day observation period. These findings indicate the promising prospects of these nanoparticles in tumor treatment.

AMPK regulates phagophore-to-autophagosome maturation

Autophagy is an important metabolic pathway that can non-selectively recycle cellular material or lead to targeted degradation of protein aggregates or damaged organelles. Autophagosome formation starts with autophagy factors accumulating on lipid vesicles containing ATG9. These phagophores attach to donor membranes, expand via ATG2-mediated lipid transfer, capture cargo, and mature into autophagosomes, ultimately fusing with lysosomes for their degradation. Autophagy can be activated by nutrient stress, for example, by a reduction in the cellular levels of amino acids. In contrast, how autophagy is regulated by low cellular ATP levels via the AMP-activated protein kinase (AMPK), an important therapeutic target, is less clear. Using live-cell imaging and an automated image analysis pipeline, we systematically dissect how nutrient starvation regulates autophagosome biogenesis. We demonstrate that glucose starvation downregulates autophagosome maturation by AMPK-mediated inhibition of phagophore tethering to donor membrane. Our results clarify AMPKs regulatory role in autophagy and highlight its potential as a therapeutic target to reduce autophagy.

The combination therapy using tyrosine kinase receptors inhibitors and repurposed drugs to target patient-derived glioblastoma stem cells

The lesson from many studies investigating the efficacy of targeted therapy in glioblastoma (GBM) showed that a future perspective should be focused on combining multiple target treatments. Our research aimed to assess the efficacy of drug combinations against glioblastoma stem cells (GSCs). Patient-derived cells U3042, U3009, and U3039 were obtained from the Human Glioblastoma Cell Culture resource. Additionally, the study was conducted on a GBM commercial U251 cell line. Gene expression analysis related to receptor tyrosine kinases (RTKs), stem cell markers and genes associated with significant molecular targets was performed, and selected proteins encoded by these genes were assessed using the immunofluorescence and flow cytometry methods. The cytotoxicity studies were preceded by analyzing the expression of specific proteins that serve as targets for selected drugs. The cytotoxicity study using the MTS assay was conducted to evaluate the effects of selected drugs/candidates in monotherapy and combinations. The most cytotoxic compounds for U3042 cells were Disulfiram combined with Copper gluconate (DSF/Cu), Dacomitinib, and Foretinib with IC50 values of 52.37 nM, 4.38 µM, and 4.54 µM after 24 h incubation, respectively. Interactions were assessed using SynergyFinder Plus software. The analysis enabled the identification of the most effective drug combinations against patient-derived GSCs. Our findings indicate that the most promising drug combinations are Dacomitinib and Foretinib, Dacomitinib and DSF/Cu, and Foretinib and AZD3759. Since most tested combinations have not been previously examined against glioblastoma stem-like cells, these results can shed new light on designing the therapeutic approach to target the GSC population.

Role of renin angiotensin system inhibitors and metformin in Glioblastoma Therapy: a review

Glioblastoma multiforme (GBM) is a highly aggressive and incurable disease accounting for about 10,000 deaths in the USA each year. Despite the current treatment approach which includes surgery with chemotherapy and radiation therapy, there remains a high prevalence of recurrence. Notable improvements have been observed in persons receiving concurrent antihypertensive drugs such as renin angiotensin inhibitors (RAS) or the antidiabetic drug metformin with standard therapy. Anti-tumoral effects of RAS inhibitors and metformin have been observed in in vitro and in vivo studies. Although clinical trials have shown mixed results, the potential for the use of RAS inhibitors and metformin as adjuvant GBM therapy remains promising. Nevertheless, evidence suggest that these drugs exert multimodal antitumor actions; by particularly targeting several cancer hallmarks. In this review, we highlight the results of clinical studies using multidrug cocktails containing RAS inhibitors and or metformin added to standard therapy for GBM. In addition, we highlight the possible molecular mechanisms by which these repurposed drugs with an excellent safety profile might elicit their anti-tumoral effects. RAS inhibition elicits anti-inflammatory, anti-angiogenic, and immune sensitivity effects in GBM. However, metformin promotes anti-migratory, anti-proliferative and pro-apoptotic effects mainly through the activation of AMP-activated protein kinase. Also, we discussed metformin's potential in targeting both GBM cells as well as GBM associated-stem cells. Finally, we summarize a few drug interactions that may cause an additive or antagonistic effect that may lead to adverse effects and influence treatment outcome.

Metformin use correlated with lower risk of cardiometabolic diseases and related mortality among US cancer survivors: evidence from a nationally representative cohort study

BACKGROUND

In the USA, the prolonged effective survival of cancer population has brought significant attention to the rising risk of cardiometabolic morbidity and mortality in this population. This heightened risk underscores the urgent need for research into effective pharmacological interventions for cancer survivors. Notably, metformin, a well-known metabolic regulator with pleiotropic effects, has shown protective effects against cardiometabolic disorders in diabetic individuals. Despite these promising indications, evidence supporting its efficacy in improving cardiometabolic outcomes in cancer survivors remains scarce.

METHODS

A prospective cohort was established using a nationally representative sample of cancer survivors enrolled in the US National Health and Nutrition Examination Survey (NHANES), spanning 2003 to 2018. Outcomes were derived from patient interviews, physical examinations, and public-access linked mortality archives up to 2019. The Oxidative Balance Score was utilized to assess participants' levels of oxidative stress. To evaluate the correlations between metformin use and the risk of cardiometabolic diseases and related mortality, survival analysis of cardiometabolic mortality was performed by Cox proportional hazards model, and cross-sectional analysis of cardiometabolic diseases outcomes was performed using logistic regression models. Interaction analyses were conducted to explore the specific pharmacological mechanism of metformin.

RESULTS

Among 3995 cancer survivors (weighted population, 21,671,061, weighted mean [SE] age, 62.62 [0.33] years; 2119 [53.04%] females; 2727 [68.26%] Non-Hispanic White individuals), 448 reported metformin usage. During the follow-up period of up to 17 years (median, 6.42 years), there were 1233 recorded deaths, including 481 deaths from cardiometabolic causes. Multivariable models indicated that metformin use was associated with a lower risk of all-cause (hazard ratio [HR], 0.62; 95% confidence interval [CI], 0.47-0.81) and cardiometabolic (HR, 0.65; 95% CI, 0.44-0.97) mortality compared with metformin nonusers. Metformin use was also correlated with a lower risk of total cardiovascular disease (odds ratio [OR], 0.41; 95% CI, 0.28-0.59), stroke (OR, 0.44; 95% CI, 0.26-0.74), hypertension (OR, 0.27; 95% CI, 0.14-0.52), and coronary heart disease (OR, 0.41; 95% CI, 0.21-0.78). The observed inverse associations were consistent across subgroup analyses in four specific cancer populations identified as cardiometabolic high-risk groups. Interaction analyses suggested that metformin use as compared to non-use may counter-balance oxidative stress.

CONCLUSIONS

In this cohort study involving a nationally representative population of US cancer survivors, metformin use was significantly correlated with a lower risk of cardiometabolic diseases, all-cause mortality, and cardiometabolic mortality.

Hypoxia within the glioblastoma tumor microenvironment: a master saboteur of novel treatments

Glioblastoma (GBM) tumors are the most aggressive primary brain tumors in adults that, despite maximum treatment, carry a dismal prognosis. GBM tumors exhibit tissue hypoxia, which promotes tumor aggressiveness and maintenance of glioma stem cells and creates an overall immunosuppressive landscape. This article reviews how hypoxic conditions overlap with inflammatory responses, favoring the proliferation of immunosuppressive cells and inhibiting cytotoxic T cell development. Immunotherapies, including vaccines, immune checkpoint inhibitors, and CAR-T cell therapy, represent promising avenues for GBM treatment. However, challenges such as tumor heterogeneity, immunosuppressive TME, and BBB restrictiveness hinder their effectiveness. Strategies to address these challenges, including combination therapies and targeting hypoxia, are actively being explored to improve outcomes for GBM patients. Targeting hypoxia in combination with immunotherapy represents a potential strategy to enhance treatment efficacy.

The combined treatment with ketogenic diet and metformin slows tumor growth in two mouse models of triple negative breast cancer

Background

Many tumors contain hypoxic microenvironments caused by inefficient tumor vascularization. Hypoxic tumors have been shown to resist conventional cancer therapies. Hypoxic cancer cells rely on glucose to meet their energetic and anabolic needs to fuel uncontrolled proliferation and metastasis. This glucose dependency is linked to a metabolic shift in response to hypoxic conditions.

Methods

To leverage the glucose dependency of hypoxic tumor cells, we assessed the effects of a mild reduction in systemic glucose by controlling both dietary carbohydrates with a ketogenic diet and endogenous glucose production by using metformin on two mouse models of triple-negative breast cancer (TNBC).

Results

Here, we showed that animals with TNBC treated with the combination regimen of ketogenic diet and metformin (a) had their tumor burden lowered by two-thirds, (b) displayed 38% slower tumor growth, and (c) showed 36% longer latency, compared to the animals treated with a ketogenic diet or metformin alone. As a result, lowering systemic glucose by this combined dietary and pharmacologic approach improved overall survival in our mouse TNBC models by 31 days, approximately equivalent to 3 years of life extension in human terms.

Conclusion

This preclinical study demonstrates that reducing systemic glucose by combining a ketogenic diet and metformin significantly inhibits tumor proliferation and increases overall survival. Our findings suggest a possible treatment for a broad range of hypoxic and glycolytic tumor types that can augment existing treatment options to improve patient outcomes.

Shared genetics between breast cancer and predisposing diseases identifies novel breast cancer treatment candidates

Background

Current effective breast cancer treatment options have severe side effects, highlighting a need for new therapies. Drug repurposing can accelerate improvements to care, as FDA-approved drugs have known safety and pharmacological profiles. Some drugs for other conditions, such as metformin, an antidiabetic, have been tested in clinical trials for repurposing for breast cancer. Here, we exploit the genetics of breast cancer and linked predisposing diseases to propose novel drug repurposing. We hypothesize that if a predisposing disease contributes to breast cancer pathology, identifying the pleiotropic genes related to the risk of cancer could prioritize drug targets, among all drugs treating a predisposing disease. We aim to develop a method to not only prioritize drug repurposing, but also to highlight shared etiology explaining repurposing.

Methods

We compile breast cancer's predisposing diseases from literature. For each predisposing disease, we use GWAS summary statistics to identify genes in loci showing genetic correlation with breast cancer. Then, we use a network approach to link these shared genes to canonical pathways, and similarly for all drugs treating the predisposing disease, we link their targets to pathways. In this manner, we are able to prioritize a list of drugs based on each predisposing disease, with each drug linked to a set of implicating pathways. Finally, we evaluate our recommendations against drugs currently under investigation for breast cancer.

Results

We identify 84 loci harboring mutations with positively correlated effects between breast cancer and its predisposing diseases; these contain 194 identified shared genes. Out of the 112 drugs indicated for the predisposing diseases, 76 drugs can be linked to shared genes via pathways (candidate drugs for repurposing). Fifteen out of these candidate drugs are already in advanced clinical trial phases or approved for breast cancer (OR = 9.28, p = 7.99e-03, one-sided Fisher's exact test), highlighting the ability of our approach to identify likely successful candidate drugs for repurposing.

Conclusions

Our novel approach accelerates drug repurposing for breast cancer by leveraging shared genetics with its known risk factors. The result provides 59 novel candidate drugs alongside biological insights supporting each recommendation.

Recent advances in understanding the mechanisms in skeletal muscle of interaction between exercise and frontline antihyperglycemic drugs

Regular exercise and antihyperglycemic drugs are front-line treatments for type-2 diabetes and related metabolic disorders. Leading drugs are metformin, sodium-glucose cotransporter-2 inhibitors, and glucagon-like peptide 1 receptor agonists. Each class has strong individual efficacy to treat hyperglycemia, yet the combination with exercise can yield varied results, some of which include blunting of expected metabolic benefits. Skeletal muscle insulin resistance contributes to the development of type-2 diabetes while improvements in skeletal muscle insulin signaling are among key adaptations to exercise training. The current review identifies recent advances into the mechanisms, with an emphasis on skeletal muscle, of the interaction between exercise and these common antihyperglycemic drugs. The review is written toward researchers and thus highlights specific gaps in knowledge and considerations for future study directions.

A novel inhibitor of the mitochondrial respiratory complex I with uncoupling properties exerts potent antitumor activity

Cancer cells are highly dependent on bioenergetic processes to support their growth and survival. Disruption of metabolic pathways, particularly by targeting the mitochondrial electron transport chain complexes (ETC-I to V) has become an attractive therapeutic strategy. As a result, the search for clinically effective new respiratory chain inhibitors with minimized adverse effects is a major goal. Here, we characterize a new OXPHOS inhibitor compound called MS-L6, which behaves as an inhibitor of ETC-I, combining inhibition of NADH oxidation and uncoupling effect. MS-L6 is effective on both intact and sub-mitochondrial particles, indicating that its efficacy does not depend on its accumulation within the mitochondria. MS-L6 reduces ATP synthesis and induces a metabolic shift with increased glucose consumption and lactate production in cancer cell lines. MS-L6 either dose-dependently inhibits cell proliferation or induces cell death in a variety of cancer cell lines, including B-cell and T-cell lymphomas as well as pediatric sarcoma. Ectopic expression of Saccharomyces cerevisiae NADH dehydrogenase (NDI-1) partially restores the viability of B-lymphoma cells treated with MS-L6, demonstrating that the inhibition of NADH oxidation is functionally linked to its cytotoxic effect. Furthermore, MS-L6 administration induces robust inhibition of lymphoma tumor growth in two murine xenograft models without toxicity. Thus, our data present MS-L6 as an inhibitor of OXPHOS, with a dual mechanism of action on the respiratory chain and with potent antitumor properties in preclinical models, positioning it as the pioneering member of a promising drug class to be evaluated for cancer therapy. MS-L6 exerts dual mitochondrial effects: ETC-I inhibition and uncoupling of OXPHOS. In cancer cells, MS-L6 inhibited ETC-I at least 5 times more than in isolated rat hepatocytes. These mitochondrial effects lead to energy collapse in cancer cells, resulting in proliferation arrest and cell death. In contrast, hepatocytes which completely and rapidly inactivated this molecule, restored their energy status and survived exposure to MS-L6 without apparent toxicity.

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

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

Metabolic dysfunction-associated profiles and subsequent site-specific risk of obesity-related cancers among Chinese patients with diabetes: a retrospective cohort study

OBJECTIVES

To compare metabolic dysfunction-associated profiles between patients with diabetes who developed different obesity-related site-specific cancers and those who remained free of cancer during follow-up.

DESIGN

Retrospective cohort study.

SETTING

Public general outpatient clinics in Hong Kong.

PARTICIPANTS

Patients with diabetes without a history of malignancy (n=391 921).

PRIMARY OUTCOME MEASURES

The outcomes of interest were diagnosis of site-specific cancers (colon and rectum, liver, pancreas, bladder, kidney and stomach) during follow-up. Cox proportional hazards regression was applied to assess the associations between metabolic dysfunction and other clinical factors with each site-specific cancer.

RESULTS

Each 0.1 increase in waist-to-hip ratio was associated with an 11%-35% elevated risk of colorectal, bladder and liver cancers. Each 1% increase in glycated haemoglobin was linked to a 4%-9% higher risk of liver and pancreatic cancers. While low-density lipoprotein cholesterol and triglycerides were inversely associated with the risk of liver and pancreatic cancers, high-density lipoprotein cholesterol was negatively associated with pancreatic, gastric and kidney cancers, but positively associated with liver cancer. Furthermore, liver cirrhosis was linked to a 56% increased risk of pancreatic cancer. No significant association between hypertension and cancer risk was found.

CONCLUSIONS

Metabolic dysfunction-associated profiles contribute to different obesity-related cancer outcomes differentially among patients with diabetes. This study may provide evidence to help identify cancer prevention targets during routine diabetes care.

The Past and Future of Inflammation as a Target to Cancer Prevention

Inflammation is an essential defense mechanism in which innate immune cells are coordinately activated on encounter of harmful stimuli, including pathogens, tissue injury, and toxic compounds and metabolites to neutralize and eliminate the instigator and initiate healing and regeneration. Properly terminated inflammation is vital to health, but uncontrolled runaway inflammation that becomes chronic begets a variety of inflammatory and metabolic diseases and increases cancer risk. Making damaged tissues behave as "wounds that do not heal" and sustaining the production of growth factors whose physiologic function is tissue healing, chronic inflammation accelerates cancer emergence from premalignant lesions. In 1863, Rudolf Virchow, a leading German pathologist, suggested a possible association between inflammation and tumor formation, but it took another 140 years to fully elucidate and appreciate the tumorigenic role of inflammation. Key findings outlined molecular events in the inflammatory cascade that promote cancer onset and progression and enabled a better appreciation of when and where inflammation should be inhibited. These efforts triggered ongoing research work to discover and develop inflammation-reducing chemopreventive strategies for decreasing cancer risk and incidence.

Ianus Bifrons: The Two Faces of Metformin

The ancient Roman god Ianus was a mysterious divinity with two opposite faces, one looking at the past and the other looking to the future. Likewise, metformin is an "old" drug, with one side looking at the metabolic role and the other looking at the anti-proliferative mechanism; therefore, it represents a typical and ideal bridge between diabetes and cancer. Metformin (1,1-dimethylbiguanidine hydrochloride) is a drug that has long been in use for the treatment of type 2 diabetes mellitus, but recently evidence is growing about its potential use in other metabolic conditions and in proliferative-associated diseases. The aim of this paper is to retrace, from a historical perspective, the knowledge of this molecule, shedding light on the subcellular mechanisms of action involved in metabolism as well as cellular and tissue growth. The intra-tumoral pharmacodynamic effects of metformin and its possible role in the management of different neoplasms are evaluated and debated. The etymology of the name Ianus is probably from the Latin term ianua, which means door. How many new doors will this old drug be able to open?

Identification of glucose-independent and reversible metabolic pathways associated with anti-proliferative effect of metformin in liver cancer cells

INTRODUCTION

Despite the ability of cancer cells to survive glucose deprivation, most studies on anti-cancer effect of metformin explored its impact on glucose metabolism. No study ever examined whether its anti-cancer effect is reversible. Existing evidences warrant understanding of glucose-independent non-cytotoxic anti-proliferative effect of metformin to rationalize its role in liver cancer.

OBJECTIVES

Characterization of glucose-independent anti-proliferative metabolic effects of metformin as well as analysis of their reversibility in liver cancer cells.

METHODOLOGY

The dose-dependent effects of metformin on HepG2 cells were examined in presence and absence of glucose. The longitudinal evolution of metabolome was analyzed along with gene and protein expression as well as their correlations with and reversibility of cellular phenotype and metabolic signatures.

RESULTS

Metformin concentrations up to 2.5 mM were found to be anti-proliferative irrespective of presence of glucose without significant increase in cytotoxicity. Apart from mitochondrial impairment, derangement of fatty acid desaturation, one-carbon, glutathione, and polyamine metabolism were associated with metformin treatment irrespective of glucose supplementation. Depletion of pantothenic acid, downregulation of essential amino acid uptake and metabolism alongside purine salvage were identified as novel glucose-independent effects of metformin. These were significantly correlated with cMyc expression and reduction in proliferation. Rescue experiments established reversibility upon metformin withdrawal and tight association between proliferation, metabotype, and cMyc expression.

CONCLUSIONS

The derangement of multiple glucose-independent metabolic pathways, which are often upregulated in therapy-resistant cancer, and concomitant cMyc downregulation coordinately contribute to the anti-proliferative effect of metformin in liver cancer cells. These are reversible and may influence its therapeutic utility.

Metformin and Glucose Concentration as Limiting Factors in Retinal Pigment Epithelial Cell Viability and Proliferation

Metformin is a well-established drug for the treatment of type 2 diabetes; however, the mechanism of action has not been well described and many aspects of how it truly acts are still unknown. Moreover, regarding in vitro experiments, the glycaemic status when metformin is used is generally not considered, which, added to the suprapharmacological drug concentrations that are commonly employed in research, has resulted in gaps of its mechanism of action. The aim of this study was to determine how glucose and metformin concentrations influence cell culture. Considering that diabetic retinopathy is one of the most common complications of diabetes, a retinal pigment epithelial cell line was selected, and cell viability and proliferation rates were measured at different glucose and metformin concentrations. As expected, glucose concentration by itself positively influenced cell proliferation rates. When the metformin was considered, results were conditioned, as well, by metformin concentration. This conditioning resulted in cell death when high concentrations of metformin were used under physiological concentrations of glucose, while this did not happen when clinically relevant concentrations of metformin were used independently of glucose status. Our study shows the importance of in vitro cell growth conditions when drug effects such as metformin's are being analysed.

Metabolomics analysis reveals novel serum metabolite alterations in cancer cachexia

Background

Cachexia is a body wasting syndrome that significantly affects well-being and prognosis of cancer patients, without effective treatment. Serum metabolites take part in pathophysiological processes of cancer cachexia, but apart from altered levels of select serum metabolites, little is known on the global changes of the overall serum metabolome, which represents a functional readout of the whole-body metabolic state. Here, we aimed to comprehensively characterize serum metabolite alterations and analyze associated pathways in cachectic cancer patients to gain new insights that could help instruct strategies for novel interventions of greater clinical benefit.

Methods

Serum was sampled from 120 metastatic cancer patients (stage UICC IV). Patients were grouped as cachectic or non-cachectic according to the criteria for cancer cachexia agreed upon international consensus (main criterium: weight loss adjusted to body mass index). Samples were pooled by cachexia phenotype and assayed using non-targeted gas chromatography-mass spectrometry (GC-MS). Normalized metabolite levels were compared using t-test (p < 0.05, adjusted for false discovery rate) and partial least squares discriminant analysis (PLS-DA). Machine-learning models were applied to identify metabolite signatures for separating cachexia states. Significant metabolites underwent MetaboAnalyst 5.0 pathway analysis.

Results

Comparative analyses included 78 cachectic and 42 non-cachectic patients. Cachectic patients exhibited 19 annotable, significantly elevated (including glucose and fructose) or decreased (mostly amino acids) metabolites associating with aminoacyl-tRNA, glutathione and amino acid metabolism pathways. PLS-DA showed distinct clusters (accuracy: 85.6%), and machine-learning models identified metabolic signatures for separating cachectic states (accuracy: 83.2%; area under ROC: 88.0%). We newly identified altered blood levels of erythronic acid and glucuronic acid in human cancer cachexia, potentially linked to pentose-phosphate and detoxification pathways.

Conclusion

We found both known and yet unknown serum metabolite and metabolic pathway alterations in cachectic cancer patients that collectively support a whole-body metabolic state with impaired detoxification capability, altered glucose and fructose metabolism, and substrate supply for increased and/or distinct metabolic needs of cachexia-associated tumors. These findings together imply vulnerabilities, dependencies and targets for novel interventions that have potential to make a significant impact on future research in an important field of cancer patient care.

Efficacy of metformin and electrical pulses in breast cancer MDA-MB-231 cells

Aim

Triple-negative breast cancer (TNBC) is a very aggressive subset of breast cancer, with limited treatment options, due to the lack of three commonly targeted receptors, which merits the need for novel treatments for TNBC. Towards this need, the use of metformin (Met), the most widely used type-2 diabetes drug worldwide, was explored as a repurposed anticancer agent. Cancer being a metabolic disease, the modulation of two crucial metabolites, glucose, and reactive oxygen species (ROS), is studied in MDA-MB-231 TNBC cells, using Met in the presence of electrical pulses (EP) to enhance the drug efficacy.

Methods

MDA-MB-231, human TNBC cells were treated with Met in the presence of EP, with various concentrations Met of 1 mmol/L, 2.5 mmol/L, 5 mmol/L, and 10 mmol/L. EP of 500 V/cm, 800 V/cm, and 1,000 V/cm (with a pulse width of 100 µs at 1 s intervals) were applied to TNBC and the impact of these two treatments was studied. Various assays, including cell viability, microscopic inspection, glucose, ROS, and wound healing assay, were performed to characterize the response of the cells to the combination treatment.

Results

Combining 1,000 V/cm with 5 mmol/L Met yielded cell viability as low as 42.6% at 24 h. The glucose level was reduced by 5.60-fold and the ROS levels were increased by 9.56-fold compared to the control, leading to apoptotic cell death.

Conclusions

The results indicate the enhanced anticancer effect of Met in the presence of electric pulses. The cell growth is inhibited by suppressing glucose levels and elevated ROS. This shows a synergistic interplay between electroporation, Met, glucose, and ROS metabolic alterations. The results show promises for combinational therapy in TNBC patients.

Cancer Precision-Prevention trial of Metformin in adults with Li Fraumeni syndrome (MILI) undergoing yearly MRI surveillance: a randomised controlled trial protocol

BACKGROUND

Li-Fraumeni syndrome (LFS) is a rare autosomal dominant disease caused by inherited or de novo germline pathogenic variants in TP53. Individuals with LFS have a 70-100% lifetime risk of developing cancer. The current standard of care involves annual surveillance with whole-body and brain MRI (WB-MRI) and clinical review; however, there are no chemoprevention agents licensed for individuals with LFS. Preclinical studies in LFS murine models show that the anti-diabetic drug metformin is chemopreventive and, in a pilot intervention trial, short-term use of metformin was well-tolerated in adults with LFS. However, metformin's mechanism of anticancer activity in this context is unclear.

METHODS

Metformin in adults with Li-Fraumeni syndrome (MILI) is a Precision-Prevention phase II open-labelled unblinded randomised clinical trial in which 224 adults aged ≥ 16 years with LFS are randomised 1:1 to oral metformin (up to 2 mg daily) plus annual MRI surveillance or annual MRI surveillance alone for up to 5 years. The primary endpoint is to compare cumulative cancer-free survival up to 5 years (60 months) from randomisation between the intervention (metformin) and control (no metformin) arms. Secondary endpoints include a comparison of cumulative tumour-free survival at 5 years, overall survival at 5 years and clinical characteristics of emerging cancers between trial arms. Safety, toxicity and acceptability of metformin; impact of metformin on quality of life; and impact of baseline lifestyle risk factors on cancer incidence will be assessed. Exploratory end-points will evaluate the mechanism of action of metformin as a cancer preventative, identify biomarkers of response or carcinogenesis and assess WB-MRI performance as a diagnostic tool for detecting cancers in participants with LFS by assessing yield and diagnostic accuracy of WB-MRI.

DISCUSSION

Alongside a parallel MILI study being conducted by collaborators at the National Cancer Institute (NCI), MILI is the first prevention trial to be conducted in this high-risk group. The MILI study provides a unique opportunity to evaluate the efficacy of metformin as a chemopreventive alongside exploring its mechanism of anticancer action and the biological process of mutated P53-driven tumourigenesis.

TRIAL REGISTRATION

ISRCTN16699730. Registered on 28 November 2022. URL: https://www.isrctn.com/ EudraCT/CTIS number 2022-000165-41.

Stem Cell Theory of Cancer: Clinical Implications for Cellular Metabolism and Anti-Cancer Metabolomics

Although Otto Warburg may be right about the role of glycolysis versus OXPHOS in cancer metabolism, it remains unclear whether an altered metabolism is causative or correlative and is the main driver or a mere passenger in the pathogenesis of cancer. Currently, most of our successful treatments are designed to eliminate non-cancer stem cells (non-CSCs) such as differentiated cancer cells. When the treatments also happen to control CSCs or the stem-ness niche, it is often unintended, unexpected, or undetected for lack of a pertinent theory about the origin of cancer that clarifies whether cancer is a metabolic, genetic, or stem cell disease. Perhaps cellular context matters. After all, metabolic activity may be different in different cell types and their respective microenvironments-whether it is in a normal progenitor stem cell vs. progeny differentiated cell and whether it is in a malignant CSC vs. non-CSC. In this perspective, we re-examine different types of cellular metabolism, e.g., glycolytic vs. mitochondrial, of glucose, glutamine, arginine, and fatty acids in CSCs and non-CSCs. We revisit the Warburg effect, an obesity epidemic, the aspartame story, and a ketogenic diet. We propose that a pertinent scientific theory about the origin of cancer and of cancer metabolism influences the direction of cancer research as well as the design of drug versus therapy development in cancer care.