Diabetes, metformin and cancer risk in myotonic dystrophy type I

Association of glucose-lowering drug target and risk of gastrointestinal cancer: a mendelian randomization study

BACKGROUND & AIMS

Glucose-lowering drug is associated with various cancers, but the causality with gastrointestinal cancer risk is rarely reported. We aimed to explore the causality between them in this Mendelian randomization (MR) study.

METHODS

Two-sample MR, summary-data-based (SMR), mediation MR, and colocalization analyses was employed. Ten glucose-lowering drug targets (PPARG, DPP4, GLP1R, INSR, SLC5A2, ABCC8, KCNJ11, ETFDH, GPD2, PRKAB1) and seven types of gastrointestinal cancer (anal carcinoma, cardia cancer, gastric cancer, hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (ICC), pancreatic cancer, rectum cancer) were included. Patients with gastrointestinal cancers from six different large GWAS databases, including the UK Biobank and Finnish cohorts were incorporated, for discovery and external validation. Meta-analysis was employed to integrate the results from both discovery and validation cohorts, thereby ensuring the reliability of findings.

RESULTS

ABCC8/KCNJ11 were associated with pancreatic cancer risk in both two-sample MR (odds ratio (OR): 15.058, per standard deviation unit (SD) change of glucose-lowering durg target perturbation equivalent to 1 SD unit of HbA1c lowering; 95% confidence interval (95% CI): 3.824-59.295; P-value = 0.0001) and SMR (OR: 1.142; 95% CI: 1.013-1.287; P-value = 0.030) analyses. The mediation effect of body mass index (OR: 0.938; 95% CI: 0.884-0.995; proportion of mediation effect: 3.001%; P-value = 0.033) on ABCC8/KCNJ11 and pancreatic cancer was uncovered. Strong connections of DPP4 with anal carcinoma (OR: 0.123; 95% CI: 0.020-0.745; P-value = 0.023) and ICC (OR: 7.733; 95% CI: 1.743-34.310; P-value = 0.007) were detected. PPARG was associated with anal carcinoma (OR: 12.909; 95% CI: 3.217-51.795; P-value = 0.0003), HCC (OR: 36.507; 95% CI: 8.929-149.259; P-value < 0.0001), and pancreatic cancer (OR: 0.110; 95% CI: 0.071-0.172; P-value < 0.0001). SLC5A2 was connected with pancreatic cancer (OR: 8.096; 95% CI: 3.476-18.857; P-value < 0.0001). Weak evidence indicated the connections of GLP1R, GPD2, and PRKAB1 with anal carcinoma, cardia cancer, ICC, and rectum cancer. In addition, the corresponding results were consistently validated in both the validation cohorts and the integrated outcomes.

CONCLUSIONS

Some glucose-lowering drugs were associated with gastrointestinal cancer risk, which might provide new ideas for gastrointestinal cancer treatment.

Myotonic dystrophy type 1 in the COVID-19 era

INTRODUCTION

Myotonic dystrophy type 1 (DM1) is the most prevalent muscular dystrophy in adults. People with DM1 might represent a high-risk population for respiratory infections, including COVID-19. Our aim was to evaluate the characteristics of COVID-19 infection and vaccination rate in DM1 patients.

METHODS

This cross-sectional cohort study included 89 patients from the Serbian registry for myotonic dystrophies. Mean age at testing was 48.4 ± 10.4 years with 41 (46.1%) male patients. Mean duration of the disease was 24.0 ± 10.3 years.

RESULTS

COVID-19 infection was reported by 36 (40.4%) DM1 patients. Around 14% of patients had a more severe form of COVID-19 requiring hospitalization. The severity of COVID-19 was in accordance with the duration of DM1. A severe form of COVID-19 was reported in 20.8% of patients who were not vaccinated against SARS-CoV-2 and in none of the vaccinated ones. The majority of 89 tested patients (66.3%) were vaccinated against SARS-CoV-2. About half of them (54.2%) received three doses and 35.6% two doses of vaccine. Mild adverse events after vaccination were recorded in 20.3% of patients.

CONCLUSIONS

The percentage of DM1 patients who suffered from COVID-19 was like in general population, but with more severe forms in DM1, especially in patients with longer DM1 duration. The study indicated an overall favorable safety profile of COVID-19 vaccines among individuals with DM1 and its ability to protect them from severe COVID-19.

Use of Antihyperglycemic Drugs and Risk of Cancer in Patients with Diabetes

PURPOSE OF REVIEW

Diabetes is associated with an increased risk for several types of cancer. Therefore, use of antihyperglycemic medications to lower blood glucose may modify cancer risk. Here we review available data on the link between the most common classes of antihyperglycemic agents and cancer risk among patients with diabetes.

RECENT FINDINGS

A database search was conducted between February 2022 and June 2022 on PubMed and Embase for systematic reviews and meta-analyses investigating the association between antihyperglycemic agents and risk of cancer. Use of biguanides such as metformin is associated with 20-30% lower risk for all cancer incidence, and somewhat greater benefit for cancer-related mortality. Alpha-glucosidase inhibitors, e.g., acarbose, have not been consistently associated with cancer. Similarly, no consistent effects have been reported for thiazolidinediones, but the relationship with cancer seems to depend on the type of drug, dose, and duration of treatment. Exposure to various types of incretin-based therapies (glucagon-like peptide-1 agonists and dipeptidyl peptidase-4 inhibitors) has not been found to significantly modify cancer risk. Inhibitors of sodium glucose cotransporter-2 may raise risk for bladder cancer and reduce risk for gastrointestinal cancer. Use of insulin and insulin analogs is associated with a significant increase in total cancer risk by almost 50% compared to other antihyperglycemic drugs. Likewise, insulin secretagogues like sulfonylureas have generally been linked to greater risk for cancer by ~ 20%, although these associations may be agent-specific and dose-dependent. Current evidence suggests that the risk of cancer associated with the use of antihyperglycemic medications among patients with diabetes depends on the class of drug and type of agent, dosage, and duration of treatment. More research is needed to delineate the mechanisms by which these agents affect the process of carcinogenesis.

Pharmacological and exercise-induced activation of AMPK as emerging therapies for myotonic dystrophy type 1 patients

Myotonic dystrophy type 1 (DM1) is a multisystemic disorder with variable clinical features. Currently, there is no cure or effective treatment for DM1. The disease is caused by an expansion of CUG repeats in the 3' UTR of DMPK mRNAs. Mutant DMPK mRNAs accumulate in nuclei as RNA foci and trigger an imbalance in the level and localization of RNA-binding proteins causing the characteristic missplicing events that account for the varied DM1 symptoms, a disease mechanism referred to as RNA toxicity. In recent years, multiple signalling pathways have been identified as being aberrantly regulated in skeletal muscle in response to the CUG expansion, including AMPK, a sensor of energy status, as well as a master regulator of cellular energy homeostasis. Converging lines of evidence highlight the benefits of activating AMPK signalling pharmacologically on RNA toxicity, as well as on muscle histology and function, in preclinical DM1 models. Importantly, a clinical trial with metformin, an activator of AMPK, resulted in functional benefits in DM1 patients. In addition, exercise, a known AMPK activator, has shown promising effects on RNA toxicity and muscle function in DM1 mice. Finally, clinical trials involving moderate-intensity exercise also induced functional benefits for DM1 patients. Taken together, these studies clearly demonstrate the molecular, histological and functional benefits of AMPK activation and exercise-based interventions on the DM1 phenotype. Despite these advances, several key questions remain; in particular, the extent of the true implication of AMPK in the observed beneficial improvements, as well as how, mechanistically, activation of AMPK signalling improves the DM1 pathophysiology.

Targeting Myotonic Dystrophy Type 1 with Metformin

Myotonic dystrophy type 1 (DM1) is a multisystemic disorder of genetic origin. Progressive muscular weakness, atrophy and myotonia are its most prominent neuromuscular features, while additional clinical manifestations in multiple organs are also common. Overall, DM1 features resemble accelerated aging. There is currently no cure or specific treatment for myotonic dystrophy patients. However, in recent years a great effort has been made to identify potential new therapeutic strategies for DM1 patients. Metformin is a biguanide antidiabetic drug, with potential to delay aging at cellular and organismal levels. In DM1, different studies revealed that metformin rescues multiple phenotypes of the disease. This review provides an overview of recent findings describing metformin as a novel therapy to combat DM1 and their link with aging.

Hereditary gynecologic tumors and precision cancer medicine

Gynecologic cancers are more often caused by genetic factors than other cancers. Genetic testing has become a promising avenue for the prevention, prognosis, and treatment of cancers. This review describes molecular features of gynecologic tumors linked to hereditary syndromes, gives an overview of the current state of clinical management, and clarifies the role of gynecology in the treatment of hereditary tumors. Typical hereditary gynecologic tumors include hereditary breast and ovarian cancer, Lynch syndrome, Peutz-Jeghers syndrome, and Cowden syndrome. Multigene panel testing, which analyzes a preselected subset of genes for genetic variants, has recently become the first-choice test because it can provide more accurate risk assessment than a single test. Furthermore, comprehensive genomic cancer profiling enables personalized cancer treatment and aids in germline findings.

New developments in myotonic dystrophies from a multisystemic perspective

PURPOSE OF REVIEW

The multisystemic involvement of myotonic dystrophies (DMs) intricates disease monitoring, patients' care and trial design. This update of the multifaceted comorbidities observed in DMs aims to assist neurologists in the complex management of patients and to encourage further studies for still under-investigated aspects of the disease.

RECENT FINDINGS

We reviewed the most recent studies covering pathogenesis and clinical aspects of extra-muscular involvement in DM1 and DM2. The largest body of evidence regards the cardiac and respiratory features, for which experts' recommendations have been produced. Gastrointestinal symptoms emerge as one of the most prevalent complaints in DMs. The alteration of insulin signaling pathways, involved in gastrointestinal manifestations, carcinogenesis, muscle function, cognitive and endocrinological aspects, gain further relevance in the light of recent evidence of metformin efficacy in DM1. Still, too few studies are performed on large DM2 cohorts, so that current recommendations mainly rely on data gathered in DM1 that cannot be fully translated to DM2.

SUMMARY

Extra-muscular manifestations greatly contribute to the overall disease burden. A multidisciplinary approach is the key for the management of patients. Consensus-based recommendations for DM1 and DM2 allow high standards of care but further evidence are needed to implement these recommendations.

Myotonic dystrophy type 1 drug development: A pipeline toward the market

Myotonic dystrophy type 1 (DM1) is a multisystemic neuromuscular genetic disease with an estimated prevalence of approximately at least half a million individuals based on its vast ethnic variation. Building upon a well-known physiopathology and several proof-of-concept therapeutic approaches, herein we compile a comprehensive overview of the most recent drug development programs under preclinical and clinical evaluation. Specifically, close to two dozen drug developments, eight of which are already in clinical trials, explore a diversity of new chemical entities, drug repurposing, oligonucleotide, and gene therapy-based approaches. Of these, repurposing of tideglusib, mexiletine, or metformin appear to be therapies with the most potential to receive marketing authorization for DM1.

Cancer Biology and Prevention in Diabetes

The available evidence suggests a complex relationship between diabetes and cancer. Epidemiological data suggest a positive correlation, however, in certain types of cancer, a more complex picture emerges, such as in some site-specific cancers being specific to type I diabetes but not to type II diabetes. Reports share common and differential mechanisms which affect the relationship between diabetes and cancer. We discuss the use of antidiabetic drugs in a wide range of cancer therapy and cancer therapeutics in the development of hyperglycemia, especially antineoplastic drugs which often induce hyperglycemia by targeting insulin/IGF-1 signaling. Similarly, dipeptidyl peptidase 4 (DPP-4), a well-known target in type II diabetes mellitus, has differential effects on cancer types. Past studies suggest a protective role of DPP-4 inhibitors, but recent studies show that DPP-4 inhibition induces cancer metastasis. Moreover, molecular pathological mechanisms of cancer in diabetes are currently largely unclear. The cancer-causing mechanisms in diabetes have been shown to be complex, including excessive ROS-formation, destruction of essential biomolecules, chronic inflammation, and impaired healing phenomena, collectively leading to carcinogenesis in diabetic conditions. Diabetes-associated epithelial-to-mesenchymal transition (EMT) and endothelial-to-mesenchymal transition (EndMT) contribute to cancer-associated fibroblast (CAF) formation in tumors, allowing the epithelium and endothelium to enable tumor cell extravasation. In this review, we discuss the risk of cancer associated with anti-diabetic therapies, including DPP-4 inhibitors and SGLT2 inhibitors, and the role of catechol-o-methyltransferase (COMT), AMPK, and cell-specific glucocorticoid receptors in cancer biology. We explore possible mechanistic links between diabetes and cancer biology and discuss new therapeutic approaches.

Myotonic Dystrophy type 1 cells display impaired metabolism and mitochondrial dysfunction that are reversed by metformin

Myotonic dystrophy type 1 (DM1; MIM #160900) is an autosomal dominant disorder, clinically characterized by progressive muscular weakness and multisystem degeneration. The broad phenotypes observed in patients with DM1 resemble the appearance of a multisystem accelerated aging process. However, the molecular mechanisms underlying these phenotypes remain largely unknown. In this study, we characterized the impact of metabolism and mitochondria on fibroblasts and peripheral blood mononuclear cells (PBMCs) derived from patients with DM1 and healthy individuals. Our results revealed a decrease in oxidative phosphorylation system (OXPHOS) activity, oxygen consumption rate (OCR), ATP production, energy metabolism, and mitochondrial dynamics in DM1 fibroblasts, as well as increased accumulation of reactive oxygen species (ROS). PBMCs of DM1 patients also displayed reduced mitochondrial dynamics and energy metabolism. Moreover, treatment with metformin reversed the metabolic and mitochondrial defects as well as additional accelerated aging phenotypes, such as impaired proliferation, in DM1-derived fibroblasts. Our results identify impaired cell metabolism and mitochondrial dysfunction as important drivers of DM1 pathophysiology and, therefore, reveal the efficacy of metformin treatment in a pre-clinical setting.