Cyclin-dependent kinase 9 (CDK9) promotes transcriptional elongation through RNAPII pause release. We now report that CDK9 is also essential for maintaining gene silencing at heterochromatic loci. ...Through a live cell drug screen with genetic confirmation, we discovered that CDK9 inhibition reactivates epigenetically silenced genes in cancer, leading to restored tumor suppressor gene expression, cell differentiation, and activation of endogenous retrovirus genes. CDK9 inhibition dephosphorylates the SWI/SNF protein BRG1, which contributes to gene reactivation. By optimization through gene expression, we developed a highly selective CDK9 inhibitor (MC180295, IC50 = 5 nM) that has broad anti-cancer activity in vitro and is effective in in vivo cancer models. Additionally, CDK9 inhibition sensitizes to the immune checkpoint inhibitor α-PD-1 in vivo, making it an excellent target for epigenetic therapy of cancer.
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•CDK9 inhibition reactivates epigenetically silenced genes in multiple cancer cells•CDK9 binds to and phosphorylates BRG1, which contributes to gene silencing•We developed a novel potent and selective CDK9 inhibitor, MC180295•MC180295 shows promising anti-tumoral and immunosensitization activity
Inhibition of a kinase typically associated with transcription elongation complexes leads to reactivation of tumor suppressor genes and increases sensitivity to immunotherapy in cancer models.
Abstract
Neuroblastoma, the most common type of pediatric extracranial solid tumor, causes 10% of childhood cancer deaths. Despite intensive multimodal treatment, the outcomes of high-risk ...neuroblastoma remain poor. We urgently need to develop new therapies with safe long-term toxicity profiles for rapid testing in clinical trials. Drug repurposing is a promising approach to meet these needs. Here, we investigated disulfiram, a safe and successful chronic alcoholism treatment with known anticancer and epigenetic effects. Disulfiram efficiently induced cell cycle arrest and decreased the viability of six human neuroblastoma cell lines at half-maximal inhibitory concentrations up to 20 times lower than its peak clinical plasma level in patients treated for chronic alcoholism. Disulfiram shifted neuroblastoma transcriptome, decreasing MYCN levels and activating neuronal differentiation. Consistently, disulfiram significantly reduced the protein level of lysine acetyltransferase 2A (KAT2A), drastically reducing acetylation of its target residues on histone H3. To investigate disulfiram’s anticancer effects in an in vivo model of high-risk neuroblastoma, we developed a disulfiram-loaded emulsion to deliver the highly liposoluble drug. Treatment with the emulsion significantly delayed neuroblastoma progression in mice. These results identify KAT2A as a novel target of disulfiram, which directly impacts neuroblastoma epigenetics and is a promising candidate for repurposing to treat pediatric neuroblastoma.
DNA methylation is commonly thought of as a "molecular lock" that leads to permanent gene silencing. To investigate this notion, we tested 24 different histone deacetylase inhibitors (HDACi) on colon ...cancer cells that harbor a GFP locus stably integrated and silenced by a hypermethylated cytomegalovirus (CMV) promoter. We found that HDACi efficiently reactivated expression of GFP and many other endogenous genes silenced by DNA hypermethylation. After treatment, all promoters were marked with active chromatin, yet DNA hypermethylation did not change. Thus, DNA methylation could not prevent gene reactivation by drug-induced resetting of the chromatin state. In evaluating the relative contribution of DNA methylation and histone modifications to stable gene silencing, we followed expression levels of GFP and other genes silenced by DNA hypermethylation over time after treatment with HDACi or DNA-demethylating drugs. Reactivation of methylated loci by HDACi was detectable for only 2 weeks, whereas DNA-demethylating drugs induced permanent epigenetic reprogramming. Therefore, DNA methylation cannot be considered as a lock for gene expression but rather as a memory signal for long-term maintenance of gene silencing. These findings define chromatin as an important druggable target for cancer epigenetic therapy and suggest that removal of DNA methylation signals is required to achieve long-term gene reactivation.
Rituximab, the first monoclonal antibody approved for the treatment of lymphoma, eventually became one of the most popular and versatile drugs ever in terms of clinical application and revenue. Since ...its patent expiration, and consequently, the loss of exclusivity of the original biologic, its repurposing as an off‐label drug has increased dramatically, propelled by the development and commercialization of its many biosimilars. Currently, rituximab is prescribed worldwide to treat a vast range of autoimmune diseases mediated by B cells. Here, we present a comprehensive overview of rituximab repurposing in 115 autoimmune diseases across 17 medical specialties, sourced from over 1530 publications. Our work highlights the extent of its off‐label use and clinical benefits, underlining the success of rituximab repurposing for both common and orphan immune‐related diseases. We discuss the scientific mechanism associated with its clinical efficacy and provide additional indications for which rituximab could be investigated. Our study presents rituximab as a flagship example of drug repurposing owing to its central role in targeting cluster of differentiate 20 positive (CD20) B cells in 115 autoimmune diseases.
B cell functions include: (A) acting as antigen‐presenting cells (APCs) through B‐cell antigen receptors (BCRs), (B) interacting with T cells via the major histocompatibility complex class II (MHC II) and T‐cell receptors (TCRs), (C) producing autoantibodies, and (D) producing inflammatory cytokines. When aberrant, they employ these mechanisms against self, fostering autoimmunity. By depleting CD20+ B cells, rituximab rewires the immune system such that self‐proteins are no longer perceived as foreign, benefitting over a hundred autoimmune disorders in 17 medical disciplines.
Targeting epigenetic pathways is a promising approach for cancer therapy. Here, we report on the unexpected finding that targeting calcium signaling can reverse epigenetic silencing of tumor ...suppressor genes (TSG). In a screen for drugs that reactivate silenced gene expression in colon cancer cells, we found three classical epigenetic targeted drugs (DNA methylation and histone deacetylase inhibitors) and 11 other drugs that induced methylated and silenced CpG island promoters driving a reporter gene (GFP) as well as endogenous TSGs in multiple cancer cell lines. These newly identified drugs, most prominently cardiac glycosides, did not change DNA methylation locally or histone modifications globally. Instead, all 11 drugs altered calcium signaling and triggered calcium-calmodulin kinase (CamK) activity, leading to MeCP2 nuclear exclusion. Blocking CamK activity abolished gene reactivation and cancer cell killing by these drugs, showing that triggering calcium fluxes is an essential component of their epigenetic mechanism of action. Our data identify calcium signaling as a new pathway that can be targeted to reactivate TSGs in cancer.
Neurologic disorders, mainly Guillain-Barré syndrome and Parsonage–Turner syndrome (PTS), have been described in patients with hepatitis E virus (HEV) infection in industrialized and developing ...countries. We report a wider range of neurologic disorders in nonimmunocompromised patients with acute HEV infection. Data from 15 French immunocompetent patients with acute HEV infection and neurologic disorders were retrospectively recorded from January 2006 through June 2013. The disorders could be divided into 4 main entities: mononeuritis multiplex, PTS, meningoradiculitis, and acute demyelinating neuropathy. HEV infection was treated with ribavirin in 3 patients (for PTS or mononeuritis multiplex). One patient was treated with corticosteroids (for mononeuropathy multiplex), and 5 others received intravenous immunoglobulin (for PTS, meningoradiculitis, Guillain-Barré syndrome, or Miller Fisher syndrome). We conclude that pleiotropic neurologic disorders are seen in HEV-infected immunocompetent patients. Patients with acute neurologic manifestations and aminotransferase abnormalities should be screened for HEV infection.
Non-small cell lung carcinoma (NSCLC) is a leading cause of cancer-related death and represents a major health burden worldwide. Current therapies for NSCLC include chemotherapy, immunotherapy, and ...targeted molecular agents such as tyrosine kinase inhibitors and epigenetic drugs such as DNA methyltransferase inhibitors. However, survival rates remain low for patients with NSCLC, especially those with metastatic disease. A major cause for therapeutic failure is drug resistance, highlighting the need for novel therapies and combination strategies. Given that epigenetic modulators such as protein arginine methyltransferases (PRMTs) are frequently overexpressed in cancers, PRMT inhibitors are a promising class of cancer therapeutics. We screened a library of epigenetic and anticancer drugs to identify compounds that would synergize with MS023, a type I PRMT inhibitor, in decreasing the viability of methylthioadenosine phosphorylase (MTAP)-negative NSCLC cells.
Among 181 compounds, we identified PARP inhibitors (PARPi) as having a strong synergistic interaction with type I PRMT inhibition. The combination of MS023 and the PARP inhibitor BMN-673 (Talazoparib) demonstrated strong synergistic interaction at low nanomolar concentrations in MTAP-negative NSCLC cell lines A549, SK-LU-1 and HCC4006. The re-introduction of MTAP decreased the sensitivity of the combination therapy in A549. The combination therapy resulted in elevated γ-H2AX foci indicating increased DNA damage causing decreased cell viability. Lastly, the combination therapy was effective in PARPi resistant ovarian cancer cells, suggesting that type I PRMT inhibitors could mitigate PARPi resistance, thus potentially having an important clinical impact for cancer treatment.
These findings identify a novel cancer drug combination therapy, which is more potent than the separate single-agent therapies. Thus, combining PARP inhibitors and type I PRMT inhibitors represents a new therapeutic opportunity for MTAP-negative NSCLC and certain cancer cells resistant to PARP inhibitors.
Worker and queen bees are genetically indistinguishable. However, queen bees are fertile, larger and have a longer lifespan than their female worker counterparts. Differential feeding of larvae with ...royal jelly controls this caste switching. There is emerging evidence that the queen‐bee phenotype is driven by epigenetic mechanisms. In this study, we show that royal jelly—the secretion produced by the hypopharyngeal and mandibular glands of worker bees—has histone deacetylase inhibitor (HDACi) activity. A fatty acid, (E)‐10‐hydroxy‐2‐decenoic acid (10HDA), which accounts for up to 5% of royal jelly, harbours this HDACi activity. Furthermore, 10HDA can reactivate the expression of epigenetically silenced genes in mammalian cells. Thus, the epigenetic regulation of queen‐bee development is probably driven, in part, by HDACi activity in royal jelly.
Royal jelly, which is produced by worker bees to establish and maintain a queen bee phenotype, is shown to possess histone deacetylase inhibitor (HDACi) activity. Thus, the epigenetic regulation of queen bee development is likely driven, in part, by HDACi activity in royal jelly.
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