Doxorubicin Inhibits Phosphatidylserine Decarboxylase and Modifies Mitochondrial Membrane Composition in HeLa Cells

Design of smart chemotherapy of doxorubicin hydrochloride using nanostructured lipid carriers and solid lipid nanoparticles for improved anticancer efficacy

Doxorubicin hydrochloride (DOX) is an anticancer agent used in cancer chemotherapy. The purpose of this study was to design nanostructured lipid carriers (NLCs) of DOX as smart chemotherapy to improve its photostability and anticancer efficacy. The characteristics of DOX and DOX-loaded NLCs were investigated using UV-Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, particle size, and zeta potential study. The cytotoxicity of DOX was evaluated against three cancer cell lines (HeLa, A549, and CT-26). The particle size and zeta potential were in the range 58.45-94.08 nm and -5.80 mV - -18.27 mV, respectively. The chemical interactions, particularly hydrogen bonding and van der Waals forces, between DOX and the main components of NLCs was confirmed by FTIR. NLCs showed the sustained release profile of DOX. The photostability results revealed that the NLC system improved the photostability of DOX. Cytotoxicity results using the three cell lines showed that all formulations improved the anticancer efficacy of free DOX, and the efficacy was dependent on cell type and particle size. These results suggest that DOX-loaded NLCs are promising chemotherapeutic agents for cancer treatment.

Doxorubicin and other anthracyclines in cancers: Activity, chemoresistance and its overcoming

Anthracyclines have been important and effective treatments against a number of cancers since their discovery. However, their use in therapy has been complicated by severe side effects and toxicity that occur during or after treatment, including cardiotoxicity. The mode of action of anthracyclines is complex, with several mechanisms proposed. It is possible that their high toxicity is due to the large set of processes involved in anthracycline action. The development of resistance is a major barrier to successful treatment when using anthracyclines. This resistance is based on a series of mechanisms that have been studied and addressed in recent years. This work provides an overview of the anthracyclines used in cancer therapy. It discusses their mechanisms of activity, toxicity, and chemoresistance, as well as the approaches used to improve their activity, decrease their toxicity, and overcome resistance.

Synthetic lethality in large-scale integrated metabolic and regulatory network models of human cells

Synthetic lethality (SL) is a promising concept in cancer research. A wide array of computational tools has been developed to predict and exploit synthetic lethality for the identification of tumour-specific vulnerabilities. Previously, we introduced the concept of genetic Minimal Cut Sets (gMCSs), a theoretical approach to SL developed for genome-scale metabolic networks. The major challenge in our gMCS framework is to go beyond metabolic networks and extend existing algorithms to more complex protein-protein interactions. In this article, we take a step further and incorporate linear regulatory pathways into our gMCS approach. Extensive algorithmic modifications to compute gMCSs in integrated metabolic and regulatory models are presented in detail. Our extended approach is applied to calculate gMCSs in integrated models of human cells. In particular, we integrate the most recent genome-scale metabolic network, Human1, with 3 different regulatory network databases: Omnipath, Dorothea and TRRUST. Based on the computed gMCSs and transcriptomic data, we discovered new essential genes and their associated synthetic lethal for different cancer cell lines. The performance of the different integrated models is assessed with available large-scale in-vitro gene silencing data. Finally, we discuss the most relevant gene essentiality predictions based on published literature in cancer research.

pH-Responsive Nano-transferosomes of Purpurin-18 Sodium Salt and Doxorubicin for Enhanced Anticancer Efficiency by Photodynamic and Chemo Combination Therapy

Cancer is a devastating disease and a major human health concern. Various combination treatments have been developed to combat cancer. To obtain superior cancer therapy, the objective of this study was to synthesize purpurin-18 sodium salt (P18Na) and design P18Na- and doxorubicin hydrochloride (DOX)-loaded nano-transferosomes as a combination of photodynamic therapy (PDT) and chemotherapy for cancer. The characteristics of P18Na- and DOX-loaded nano-transferosomes were assessed, and the pharmacological efficacy of P18Na and DOX was determined using the HeLa and A549 cell lines. The nanodrug delivery system characteristics of the product were found to range from 98.38 to 217.50 nm and -23.63 to -41.10 mV, respectively. Further, the release of P18Na and DOX from nano-transferosomes exhibited a sustained pH-responsive behavior and burst in physiological and acidic environments, respectively. Accordingly, the nano-transferosomes effectively delivered P18Na and DOX into cancer cells, with less leakage in the body, and exhibited pH-responsive release in cancer cells. A photo-cytotoxicity study to HeLa and A549 cell lines revealed a size-dependent anti-cancer effect. These results suggest that the combined nano-transferosomes of P18Na and DOX are effective in the combination of PDT and chemotherapy for cancer.

Doxorubicin inhibits phosphatidylserine decarboxylase and confers broad-spectrum antifungal activity

As phospholipids of cell membranes, phosphatidylethanolamine (PE) and phosphatidylserine (PS) play crucial roles in glycerophospholipid metabolism. Broadly, some phospholipid biosynthesis enzymes serve as potential fungicide targets. Therefore, revealing the functions and mechanism of PE biosynthesis in plant pathogens would provide potential targets for crop disease control. We performed analyses including phenotypic characterizations, lipidomics, enzyme activity, site-directed mutagenesis, and chemical inhibition assays to study the function of PS decarboxylase-encoding gene MoPSD2 in rice blast fungus Magnaporthe oryzae. The Mopsd2 mutant was defective in development, lipid metabolism, and plant infection. The PS level increased while PE decreased in Mopsd2, consistent with the enzyme activity. Furthermore, chemical doxorubicin inhibited the enzyme activity of MoPsd2 and showed antifungal activity against 10 phytopathogenic fungi including M. oryzae and reduced disease severity of two crop diseases in the field. Three predicted doxorubicin-interacting residues are important for MoPsd2 functions. Our study demonstrates that MoPsd2 is involved in de novo PE biosynthesis and contributes to the development and plant infection of M. oryzae and that doxorubicin shows broad-spectrum antifungal activity as a fungicide candidate. The study also implicates that bacterium Streptomyces peucetius, which biosynthesizes doxorubicin, could be potentially used as an eco-friendly biocontrol agent.

Mitochondrial dysfunction and chromatin changes with autophagy-mediated survival in doxorubicin resistant cancer cell lines

Acquired chemoresistance against doxorubicin remains an obstacle in long-term treatment. The comprehensive molecular mechanism underlying the acquirement of doxorubicin resistance has not been reported. The objective of the present study is to understand the survival strategies and investigate alternate treatments for doxorubicin-resistant cervical and liver cancer cells. In this study, doxorubicin-resistant sublines were established by continuous incremental exposure of the drug to parental cervical and liver cancer cells. The transcriptome data in drug-resistant model revealed downregulated energy production pathways like glycolysis, oxidative phosphorylation, and mTOR signalling. This resulted in slow proliferation and altered mitochondrial changes in doxorubicin-resistant cells. The altered metabolic state of the resistant cells was associated with hypo-acetylation of chromatin. Pre-treatment with HDACi sensitized the drug-resistant cells to doxorubicin by increased drug accumulation in the cells, thereby leading to apoptosis. Additionally, we demonstrated that autophagy gets activated in doxorubicin-resistant cervical and liver cancer cells. Autophagy acts as pro-survival mechanism in resistant cells, as inhibition of autophagy leads to cell death. In conclusion, the data highlights survival ability of resistant cells with mitochondrial dysfunction, altered chromatin state, and pro-survival autophagy. The study proposes targeting chromatin alteration with the combinatorial treatment of HDACi with doxorubicin or survival mechanism through autophagy inhibitor against doxorubicin-resistant cancer phenotype.

Dynamic covalent chemistry in live cells for organelle targeting and enhanced photodynamic action

Organelle-specific targeting enables increasing the therapeutic index of drugs and localizing probes for better visualization of cellular processes. Current targeting strategies require conjugation of a molecule of interest with organelle-targeting ligands. Here, we propose a concept of dynamic covalent targeting of organelles where the molecule is conjugated with its ligand directly inside live cells through a dynamic covalent bond. For this purpose, we prepared a series of organelle-targeting ligands with a hydrazide residue for reacting with dyes and drugs bearing a ketone group. We show that dynamic hydrazone bond can be formed between these hydrazide ligands and a ketone-functionalized Nile Red dye (NRK) in situ in model lipid membranes or nanoemulsion droplets. Fluorescence imaging in live cells reveals that the targeting hydrazide ligands can induce preferential localization of NRK dye and an anti-cancer drug doxorubicin in plasma membranes, mitochondria and lipid droplets. Thus, with help of the dynamic covalent targeting, it becomes possible to direct a given bioactive molecule to any desired organelle inside the cell without its initial functionalization by the targeting ligand. Localizing the same NRK dye in different organelles by the hydrazide ligands is found to affect drastically its photodynamic activity, with the most pronounced phototoxic effects in mitochondria and plasma membranes. The capacity of this approach to tune biological activity of molecules can improve efficacy of drugs and help to understand better their intracellular mechanisms.

Mitochondrial-Targeted Therapy for Doxorubicin-Induced Cardiotoxicity

Anthracyclines, such as doxorubicin, are effective chemotherapeutic agents for the treatment of cancer, but their clinical use is associated with severe and potentially life-threatening cardiotoxicity. Despite decades of research, treatment options remain limited. The mitochondria is commonly considered to be the main target of doxorubicin and mitochondrial dysfunction is the hallmark of doxorubicin-induced cardiotoxicity. Here, we review the pathogenic mechanisms of doxorubicin-induced cardiotoxicity and present an update on cardioprotective strategies for this disorder. Specifically, we focus on strategies that can protect the mitochondria and cover different therapeutic modalities encompassing small molecules, post-transcriptional regulators, and mitochondrial transfer. We also discuss the shortcomings of existing models of doxorubicin-induced cardiotoxicity and explore advances in the use of human pluripotent stem cell derived cardiomyocytes as a platform to facilitate the identification of novel treatments against this disorder.

Mitochondrial Tumor Suppressors-The Energetic Enemies of Tumor Progression

Tumor suppressors represent a critical line of defense against tumorigenesis. Their mechanisms of action and the pathways they are involved in provide important insights into cancer progression, vulnerabilities, and treatment options. Although nuclear and cytosolic tumor suppressors have been extensively investigated, relatively little is known about tumor suppressors localized within the mitochondria. However, recent research has begun to uncover the roles of these important proteins in suppressing tumorigenesis. Here, we review this newly developing field and summarize available information on mitochondrial tumor suppressors.

Metabolic Reprogramming in Health and Disease

This editorial aims to summarize the six scientific papers that contributed to this Special Issue.