Lipid raft-associated PI3K/Akt/SREBP1 signaling regulates coxsackievirus A16 (CA16) replication

Regulating Cholesterol in Tumorigenesis: A Novel Paradigm for Tumor Nanotherapeutics

During the past decade, "membrane lipid therapy", which involves the regulation of the structure and function of tumor cell plasma membranes, has emerged as a new strategy for cancer treatment. Cholesterol is an important component of the tumor plasma membrane and serves an essential role in tumor initiation and progression. This review elucidates the role of cholesterol in tumorigenesis (including tumor cell proliferation, invasion/metastasis, drug resistance, and immunosuppressive microenvironment) and elaborates on the potential therapeutic targets for tumor treatment by regulating cholesterol. More meaningfully, this review provides an overview of cholesterol-integrated membrane lipid nanotherapeutics for cancer therapy through cholesterol regulation. These strategies include cholesterol biosynthesis interference, cholesterol uptake disruption, cholesterol metabolism regulation, cholesterol depletion, and cholesterol-based combination treatments. In summary, this review demonstrates the tumor nanotherapeutics based on cholesterol regulation, which will provide a reference for the further development of "membrane lipid therapy" for tumors.

Repurposing Amphotericin B and Its Liposomal Formulation for the Treatment of Human Mpox

Mpox (monkeypox) is a zoonotic viral disease caused by the mpox virus (MPXV). Recently in 2022, a multi-country Mpox outbreak has determined great concern as the disease rapidly spreads. The majority of cases are being noticed in European regions and are unrelated to endemic travel or known contact with infected individuals. In this outbreak, close sexual contact appears to be important for MPXV transmission, and an increasing prevalence in people with multiple sexual partners and in men who have sex with men has been observed. Although Vaccinia virus (VACV)-based vaccines have been shown to induce a cross-reactive and protective immune response against MPXV, limited data support their efficacy against the 2022 Mpox outbreak. Furthermore, there are no specific antiviral drugs for Mpox. Host-cell lipid rafts are small, highly dynamic plasma-membrane microdomains enriched in cholesterol, glycosphingolipids and phospholipids that have emerged as crucial surface-entry platforms for several viruses. We previously demonstrated that the antifungal drug Amphotericin B (AmphB) inhibits fungal, bacterial and viral infection of host cells through its capacity to sequester host-cell cholesterol and disrupt lipid raft architecture. In this context, we discuss the hypothesis that AmphB could inhibit MPXV infection of host cells through disruption of lipid rafts and eventually through redistribution of receptors/co-receptors mediating virus entry, thus representing an alternative or additional therapeutic tool for human Mpox.

Viral modulation of lipid rafts and their potential as putative antiviral targets

Lipid rafts are ubiquitous in cells. They are identified as cholesterol and glycosphingolipid enriched microdomains on cellular membranes. They serve as platforms for cellular communications by functioning in signal transduction and membrane trafficking. Such structural organisation fulfils cellular needs for normal function, but at the same time increases vulnerability of cells to pathogen invasion. Viruses rely heavily on lipid rafts in basically every stage of the viral life cycle for successful infection. Various mechanisms of lipid rafts modification exploited by diverse viruses for attachment, internalisation, membrane fusion, genome replication, assembly and release have been brought to light. This review focuses on virus-raft interactions and how a wide range of viruses manipulate lipid rafts at distinct stages of infection. The importance of virus-raft interactions in viral infections has inspired researchers to discover and develop antivirals that target this interaction, such as statins, methyl-β-cyclodextrin, viperin, 25-hydroxycholesterol and even anti-malarial drugs. The therapeutic modulations of lipid rafts as potential antiviral intervention from in vitro and in vivo evidence are discussed herein.

Immunostimulatory oncolytic activity of coxsackievirus A11 in human malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive solid cancer with a poor prognosis, whereas coxsackievirus A11 (CVA11) is a potential oncolytic virus for cancer treatment. We here investigated the oncolytic activity of CVA11 with human MPM cell lines. CVA11 infection was cytotoxic in all six MPM cell lines examined and showed no or minimal cytotoxicity toward normal human normal cell lines. MPM cells with a higher surface level of intercellular adhesion molecule-1 (ICAM-1) expression tended to be more susceptible to CVA11-induced cytotoxicity, and a neutralizing antibody to ICAM-1 attenuated such cytotoxicity. CVA11 infection activated signaling by Akt and extracellular signal-regulated kinase (ERK) pathways, and inhibitors of such signaling also abrogated CVA11-mediated cytotoxicity. Furthermore, CVA11 infection-triggered multiple modes of tumor cell death including apoptosis, pyroptosis, and necroptosis, and such death was accompanied by the release or exposure of the proinflammatory cytokine interleukin-1β and damage-associated molecular patterns such as calreticulin, high-mobility group box-1, annexin A1, and heat shock protein 70, which are hallmarks of immunogenic cell death. Notably, in vivo treatment of human MPM xenografts with intratumoral CVA11 injection resulted in significant suppression of tumor growth in SCID mice, and all mice infected with CVA11 showed no significant change in body weight. Our findings collectively suggest that the oncolytic activity of CVA11 for MPM is dependent on ICAM-1 as a virus receptor, as well as on Akt and ERK signaling, and that oncolytic virotherapy with CVA11 is a promising treatment modality with immunostimulatory activity for human MPM.

ARID3A plays a key regulatory role in palmitic acid-stimulated milk fat synthesis in mouse mammary epithelial cells

Palmitic acid (PA) can stimulate milk fat synthesis in mammary gland, but the specific mechanism is still unclear. In our research, we aim to explore the role and corresponding mechanism of AT-rich interaction domain 3A (ARID3A) in milk fat synthesis stimulated by PA. We found that ARID3A protein level in mouse mammary gland tissues during lactation was much higher than that during puberty and involution. ARID3A knockdown and gene activation showed that ARID3A stimulated the synthesis of triglycerides and cholesterol in HC11 cells, secretion of free fatty acids from cells and lipid droplet formation in cells. ARID3A also promoted the expression and maturation of SREBP1 in HC11 cells. PA stimulated ARID3A protein expression and SREBP1 expression and maturation in a dose-dependent manner, and the PI3K specific inhibitor LY294002 blocked the stimulation of PA on ARID3A expression. ARID3A knockdown blocked the stimulation of PA on SREBP1 protein expression and maturation. We further showed that ARID3A was localized in the nucleus and PA stimulated this localization, and ARID3A knockdown blocked the stimulation of PA on the mRNA expression of SREBP1. To sum up, our data reveal that ARID3A is a key mediator for PA to promote SREBP1 mRNA expression and stimulate milk fat synthesis in mammary epithelial cells.

Mechanisms of induction of tumors by cholesterol and potential therapeutic prospects

Increasing evidence suggested that cholesterol is an important integrant of cell membranes, that plays a key role in tumor progression, immune dysregulation, and pathological changes in epigenetic mechanisms. Based on these theories, there is a growing interest on targeting cholesterol in the treatment of cancer. Here, we comprehensively reviewed the major function of cholesterol on oncogenicity, the therapeutic targets of cholesterol and its metabolites in cancer, and provide detailed insight into the essential roles of cholesterol in mediating immune and epigenetic mechanisms of the tumor microenvironment. It is also worth mentioning that the gut microbiome is an indispensable component of cancer mediation because of its role in cholesterol metabolism. Finally, we summarized recent studies on the potential targets of cholesterol and their metabolism, to provide more therapeutic interventions in oncology.

Porcine epidemic diarrhea virus E protein suppresses RIG-I signaling-mediated interferon-β production

Porcine epidemic diarrhea virus (PEDV) encodes many multifunctional proteins that inhibit host innate immune response during virus infection. As one of important structural proteins, PEDV E protein has been found to block the production of type I interferon (IFN) in virus life cycle, but little is known about this process that E protein subverts host innate immune. Thus, in this present study, we initiated the construction of eukaryotic expression vectors to express PEDV E protein. Subsequently, cellular localization analysis was performed and the results showed that the majority of PEDV E protein distributed at cytoplasm and localized in endoplasmic reticulum (ER). Over-expression of PEDV E protein significantly inhibited poly(I:C)-induced IFN-β and IFN-stimulated genes (ISGs) productions. We also found that PEDV E protein remarkably suppressed the protein expression of RIG-I signaling-associated molecules, but all their corresponding mRNA levels remained unaffected and unchanged. Furthermore, PEDV E protein obviously interfered with the translocation of IRF3 from cytoplasm to nucleus through direct interaction with IRF3, which is crucial for the IFN-β production induced by poly(I:C). Taken together, our results suggested that PEDV E protein acts as an IFN-β antagonist through suppression of the RIG-I-mediated signaling. This study will pave the way for the further investigation into the molecular mechanisms by which PEDV E protein evades host innate immune response.