Project description:Chondrosarcomas are inherently resistant to chemotherapy and radiotherapy, pointing to an unmet need for new treatment options. Immune checkpoint inhibitors, which have shown remarkable promise in multiple solid cancer types, have limited efficacy in chondrosarcomas. Mutations in IDH1/2 genes, which result in progressive increases in DNA and histone methylation, are observed in 50% of conventional chondrosarcomas, suggesting that epigenetic dysregulation represents a potential barrier for tumor progression and target for therapeutic intervention. Here, we demonstrated that combined treatment of FDA-approved inhibitors of DNA methyltransferases (DNMTs) 5-aza-2'-deoxycytidine (5-aza), and histone deacetylases (HDACs) suberanilohydroxamic acid (SAHA) impaired the proliferation of chondrosarcoma cell lines in vitro and in xenograft studies. Transcriptomic analysis reveals that chondrosarcoma cells treated with 5-aza and SAHA markedly elevated the expression of IFN-stimulated genes including PD-L1, indicating that these epigenetic drugs induced a potent innate immune response. We demonstrated that 5-aza and SAHA resulted in both genomic and epigenomic instability, as shown by elevated DNA damage response and derepression of retrotransposons, respectively, which in turn activated pattern recognition receptors (PRRs) and the downstream IFN signaling pathways. Importantly, the cytotoxic effects of 5-aza and SAHA can be rescued by depletion of PRRs such as cGAS and MAVS, and potentiated by depletion of the RNA-editing enzyme ADAR1. Together, our results demonstrate preclinical activity of combined DNMT and HDAC inhibition against chondrosarcomas and suggest that targeted epigenetic therapies could represent a new therapeutic approach in the treatment of chondrosarcomas, and this is being tested in an ongoing clinical trial (NCT04340843).
Project description:In this study, our results demonstrated preclinical activity of combined DNMT and HDAC inhibition against chondrosarcomas and suggest that targeted epigenetic therapies could effectively augment the immune-reactivity of chondrosarcomas and may sensitize these immune-cold tumors to immune checkpoint blockade.
Project description:Sensing of microbial products by innate immune cells skew their transcriptional program to optimize anti-microbial defences. Chromatin remodeling by histone deacetylases (HDACs) plays a fundamental role in tailoring gene expression. HDAC inhibitors are among the most promising anti-cancer drugs and possess intrinsic anti-inflammatory properties. Yet, the influence of HDAC inhibition on innate immune responses to microbial infection is unknown. Here we show that HDAC inhibitors repress the expression of less than 10% of the genes expressed at baseline in BM-derived macrophages. In sharp contrast, HDAC inhibitors strongly interfere with transcriptome remodeling induced by LPS and Pam3CSK4, affecting the expression of 30-70% of genes modulated by microbial stimuli. Strikingly, HDAC inhibitors target the expression of numerous genes involved in anti-microbial host defences, encoding for microbial sensors, cytokines, chemokines, growth factors and their receptors, adhesion and signaling molecules, and molecules involved in antigen processing and presentation. At the molecular level, HDAC inhibitors do not impair mitogen-activated protein kinase, NF-kB, interferon-related factor signal and STAT1 transduction pathways, but inhibit NF-kB p65 recruitment to the promoter region of HDAC inhibitor-sensitive genes. HDAC inhibitors also inhibit the response of mouse and human DCs, splenocytes and whole blood to a broad range of microbial products and microorganisms. In agreement with these in vitro findings, HDAC inhibitors increase bacterial burden and sensitize mice to sub-lethal infection with Klebsiella pneumoniae and Candida albicans. Conversely, HDAC inhibitors confer protection in models of Pam3CSK4-induced fulminant toxic shock and severe sepsis following cecal ligation and puncture. Overall, these data substantiate the concept of immunomodulation by HDAC inhibitors, and suggest that these drugs could represent efficacious adjunctive therapy of severe sepsis. Mus musculus cells were grown in presence of LPS or LPS + TSA and pam or pam + TSA and hybrydised against a cRNA pool UMRR (from Mus musculus cells).
Project description:Treatment of established lines and primary ovarian cancer cultures with Src and MEK inhibitors, saracatinib and selumetinib, respectively, showed target kinase inhibition and synergistic induction of apoptosis and cell cycle arrest in vitro and tumor inhibition in xenografts.
Project description:MEK and BRD4 inhibitors induce cell death of subset of KRAS-mutant lung tumors in vitro and in vivo We performed microarray analysis of MEK and BRD4 inhibition alone and in combination 24 hours after treatment, prior to the induction of cell death, to analyze transcriptional changes that might be mechanistic drivers of the therapeutic effect
Project description:Modification by ubiquitin controls the stability of most cellular proteins, and deregulation contributes to a variety of human diseases such as cancer. Deubiquitinases (DUBs) remove ubiquitin from proteins, and the inhibition of DUBs has been recognized as a therapeutic strategy to induce degradation of specific proteins, a concept extendable to ‘undruggable’ targets such as transcription factors. However, this potential has remained untapped; specific small molecule inhibitors for DUBs are scarce and insights into mechanisms of action are limited. Ubiquitin specific protease (USP) 7 stabilises the oncogenic E3 ligase MDM2 that destabilises the tumour suppressor p53 and inhibition of USP7 results in MDM2 degradation and p53 re-activation in a variety of cancers. We here present two small molecule inhibitors, FT671 and FT827, that inhibit USP7 with nanomolar affinity and display exquisite specificity towards USP7 in vitro and in cells. USP7-inhibitor co-crystal structures reveal that both compounds target the auto-inhibited apo-form of USP7 and bind in proximity to the misaligned catalytic triad in a dynamic hydrophobic pocket that serves as the binding site for the ubiquitin C-terminus. The unique auto-inhibited conformation of apo USP7 differs from other USP DUBs, explaining compound selectivity. Consistent with USP7 target engagement in cells, FT671 destabilises MDM2, stabilises p53 and results in transcription of p53 target genes, induction of the tumour suppressor p21, and tumour growth inhibition in vivo.