Maduramicin induces cardiotoxicity via Rac1 signaling-independent methuosis in H9c2 cells

Repurposing methuosis-inducing anticancer drugs for anthelmintic therapy

Drug-resistant parasitic nematodes pose a grave threat to plants, animals, and humans. An innovative paradigm for treating parasitic nematodes is emphasized in this opinion. This approach relies on repurposing methuosis (a death characterized by accumulation of large vacuoles) inducing anticancer drugs as anthelmintics. We review drugs/chemicals that have shown to kill nematodes or cancerous cells by inducing multiple vacuoles that eventually coalesce and rupture. This perspective additionally offers a succinct summary on Structure-Activity Relationship (SAR) of methuosis-inducing small molecules. This strategy holds promise for the development of broad-spectrum anthelmintics, shedding light on shared molecular mechanisms between cancer and nematodes in response to these inducers, thereby potentially transforming both therapeutic domains.

Cellular Regulation of Macropinocytosis

Interest in macropinocytosis has risen in recent years owing to its function in tumorigenesis, immune reaction, and viral infection. Cancer cells utilize macropinocytosis to acquire nutrients to support their uncontrolled proliferation and energy consumption. Macropinocytosis, a highly dynamic endocytic and vesicular process, is regulated by a series of cellular signaling pathways. The activation of small GTPases in conjunction with phosphoinositide signaling pivotally regulates the process of macropinocytosis. In this review, we summarize important findings about the regulation of macropinocytosis and provide information to increase our understanding of the regulatory mechanism underlying it.

Progress in the discovery and development of small molecule methuosis inducers

Current cancer chemotherapies rely mainly on the induction of apoptosis of tumor cells, while drug resistance arising from conventional chemicals has always been a big challenge. In recent years, more and more new types of cell deaths including methuosis have been extensively investigated and recognized as potential alternative targets for future cancer treatment. Methuosis is usually caused by excessive accumulation of macropinosomes owing to ectopic activation of macropinocytosis, which can be triggered by external stimuli such as chemical agents. Increasing reports demonstrate that many small molecule compounds could specifically induce methuosis in tumor cells while showing little or no effect on normal cells. This finding raises the possibility of targeting tumor cell methuosis as an effective strategy for the prevention of cancer. Based on fast-growing studies lately, we herein provide a comprehensive overview on the overall research progress of small molecule methuosis inducers. Promisingly, previous efforts and experiences will facilitate the development of next-generation anticancer therapies.

V-ATPase V0 subunit activation mediates maduramicin-induced methuosis through blocking endolysosomal trafficking in vitro and in vivo

Methuosis, a novel cell death phenotype, is characterized by accumulation of cytoplasmic vacuolization upon external stimulus. Methuosis plays a critical role in maduramicin-induced cardiotoxicity despite the underlying mechanism is largely unknown. Herein, we aimed to investigate the origin and intracellular trafficking of cytoplasmic vacuoles, as well as the molecular mechanism of methuosis caused by maduramicin (1 μg/mL) in myocardial cells. H9c2 cells and broiler chicken were used and were exposed to maduramicin at doses of 1 μg/mL in vitro and 5 ppm-30 ppm in vivo. Morphological observation and dextran-Alexa Fluor 488 tracer experiment showed that endosomal compartments swelling and excessive macropinocytosis contributed to madurdamcin-induced methuosis. Cell counting kit-8 assay and morphology indicated pharmacological inhibition of macropinocytosis largely prevent H9c2 cells from maduramicin-triggered methuosis. In addition, late endosomal marker Rab7 and lysosomal associated membrane protein 1 (LAMP1) increased in a time-dependent manner after maduramicin treatment, and the recycling endosome marker Rab11 and ADP-ribosylation factor 6 (Arf6) were decreased by maduramicin. Vacuolar-H⁺-ATPase (V-ATPase) was activated by maduramicin, and pharmacological inhibition and genetic knockdown V0 subunit of V-ATPase restore endosomal-lysosomal trafficking and prevent H9c2 cells methuosis. Animal experiment showed that severe cardiac injury included the increase of creatine kinase (CK) and creatine kinase-MB (CK-MB), and vacuolar degeneration resembled methuosis in vivo after maduramicin treatment. Taken together, these findings demonstrate that targeting the inhibition of V-ATPase V0 subunit will prevent myocardial cells methuosis by restoring endosomal-lysosomal trafficking.

Effects of bepridil on early cardiac development of zebrafish

Bepridil is a commonly used medication for arrhythmia and heart failure. It primarily exerts hemodynamic effects by inhibiting Na⁺/K⁺ movement and regulating the Na⁺/Ca²⁺ exchange. In comparison to other Ca²⁺ inhibitors, bepridil has a long half-life and a complex pharmacology. Additionally, it is widely used in antiviral research and the treatment of various diseases. However, the toxicity of this compound and its other possible effects on embryonic development are unknown. In this study, we investigated the toxicity of bepridil on rat myocardial H9c2 cells. After treatment with bepridil, the cells became overloaded with Ca²⁺ and entered a state of cytoplasmic vacuolization and nuclear abnormality. Bepridil treatment resulted in several morphological abnormalities in zebrafish embryo models, including pericardium enlargement, yolk sac swelling, and growth stunting. The hemodynamic effects on fetal development resulted in abnormal cardiovascular circulation and myocardial weakness. After inhibiting the Ca²⁺ transmembrane, the liver of zebrafish larvae also displayed an ectopic and deficient spatial location. Additionally, the results of the RNA-seq analysis revealed the detailed gene expression profiles and metabolic responses to bepridil treatment in zebrafish embryonic development. Taken together, our study provides an important evaluation of antiarrhythmic agents for clinical use in prenatal heart patients.

Repurposing maduramicin as a novel anticancer and anti-metastasis agent for triple-negative breast cancer as enhanced by nanoemulsion

Triple-negative breast cancer (TNBC) is featured by aggression and metastasis and remains an unmet medical challenge due to high death rate. We aimed to repurpose maduramicin (MAD) as an effective drug against TNBC, and develop a nanoemulsion system to enhance anticancer efficacy of MAD. MDA-MB-231 and 4 T1 cells were used as in vitro model, and cell viability was determined by performing cell counting kit-8 and a colony-formation assay. Furthermore, MAD loaded nanoemulsion (MAD-NEs) was manufactured and characterized by a series of tests. The anticancer and anti-metastasis mechanism of MAD-NEs were assessed by performing cell cycle, apoptosis, wound-healing, transwell assay and Western blotting assays. Herein, MAD was firstly demonstrated to be an effective agent to suppress growth of TNBC cells. Subsequently, the optimized MAD-NEs were shown to have stability and high encapsulation efficiency, and could arrested cells in G0/G1 phase and induced apoptosis in TNBC cells. More importantly, MAD-NEs significantly impeded the metastasis of tumor cells, which was further demonstrated by the significant altered expression of epithelial-mesenchymal transition and extracellular matrix markers in vitro and in vivo. Moreover, compared to MAD, MAD-NEs exhibited higher efficacy in shrinking breast tumor size and repressing liver and lung metastasis in vivo, and showed excellent biocompatibility in tumor-bearing mice. The successfully prepared MAD-NEs are expected to be harnessed to suppress tumor growth, invasion and metastasis in the battle against malignant TNBC.

Proanthocyanidin oligomers extract from hawthorn mediates cell cycle arrest, apoptosis, and lysosome vacuolation on HCT116 cells

In this study, Hawthorn oligomic procyanidins extracts (HPOE) were evaluated for their anticancer activity on colorectal cancer. Our results showed that HPOE arrested HCT116 cells cycle at G2/M phase through P53-Cyclin B pathway and promoted apoptosis partly via mitochondrial (Caspase 9-Caspase 3) and death receptor (Caspase 8-Caspase 3) pathways. Meanwhile, it was found that HPOE aggravated HCT116 cells death through lysosomal vacuolation, which was verified by inhibitor/activator of P53-ILC3 signaling pathway. Taken together, HPOE exerted anticancer effects which lays the foundation for the development of functional foods for clinical colon cancer patients.