Project description:Breast cancer (BCa) remains the second leading cause of cancer-related mortalities in women, and acquired resistance to hormone therapies, such as tamoxifen, an estrogen receptor inhibitor, is a major hurdle in the treatment of luminal BCa. Another subtype, triple negative BCa (TNBC), is associated with aggressive disease and poor prognosis. The enhancer of zeste homolog 2 (EZH2), the methyltransferase component of the polycomb repressive complex 2 (PRC2), is overexpressed in BCa and has been implicated in tamoxifen resistance. In addition to its PRC2-dependent canonical transcription repressive role through catalyzing histone 3 lysine 27 trimethylation (H3K27me3), evidence suggests that EZH2 can function noncanonically, in a methyltransferase-independent manner, as a transcription activator through interacting with hormone receptors and oncogenic transcription factors. Unlike methyltransferase inhibitors, proteolysis targeting chimeras (PROTAC), which target EZH2 and interacting proteins for degradation, can suppress both activating and repressive functions of EZH2. Previous studies have suggested that PROTACs can be leveraged to inhibit TNBC cell growth. In this study, we expand our scope to test whether EZH2 targeted PROTACs can effectively inhibit luminal BCa cell growth. We find that EZH2-targeted PROTACs, MS177 and MS8815, effectively inhibited the growth luminal BCa cells, including those with acquired tamoxifen resistance, to a much greater degree when compared to methyltransferase inhibitors. Similarly, PROTACs uniquely reduced the expression of genes involved in cell cycle progression, including forkhead box M1 (FOXM1) target genes, in BCa cell lines. Likewise, promoter regions with EZH2 binding in the absence of H3K27me3 were enriched with FOXM1 target genes in both luminal BCa and TNBC cell lines, suggesting a regulatory mechanism independent of hormone receptor status. EZH2 PROTAC treatment reduced FOXM1 protein expression and increased its degradation. In clinical samples, EZH2 mRNA expression tightly correlated with FOXM1 and FOXM1 target genes. Together, this study suggests that EZH2 targeted PROTACs represent a promising avenue of research for the future treatment of BCa, including in the setting of tamoxifen resistance.
Project description:Breast cancer (BCa) remains the second leading cause of cancer-related mortalities in women, and acquired resistance to hormone therapies, such as tamoxifen, an estrogen receptor inhibitor, is a major hurdle in the treatment of luminal BCa. Another subtype, triple negative BCa (TNBC), is associated with aggressive disease and poor prognosis. The enhancer of zeste homolog 2 (EZH2), the methyltransferase component of the polycomb repressive complex 2 (PRC2), is overexpressed in BCa and has been implicated in tamoxifen resistance. In addition to its PRC2-dependent canonical transcription repressive role through catalyzing histone 3 lysine 27 trimethylation (H3K27me3), evidence suggests that EZH2 can function noncanonically, in a methyltransferase-independent manner, as a transcription activator through interacting with hormone receptors and oncogenic transcription factors. Unlike methyltransferase inhibitors, proteolysis targeting chimeras (PROTAC), which target EZH2 and interacting proteins for degradation, can suppress both activating and repressive functions of EZH2. Previous studies have suggested that PROTACs can be leveraged to inhibit TNBC cell growth. In this study, we expand our scope to test whether EZH2 targeted PROTACs can effectively inhibit luminal BCa cell growth. We find that EZH2-targeted PROTACs, MS177 and MS8815, effectively inhibited the growth luminal BCa cells, including those with acquired tamoxifen resistance, to a much greater degree when compared to methyltransferase inhibitors. Similarly, PROTACs uniquely reduced the expression of genes involved in cell cycle progression, including forkhead box M1 (FOXM1) target genes, in BCa cell lines. Likewise, promoter regions with EZH2 binding in the absence of H3K27me3 were enriched with FOXM1 target genes in both luminal BCa and TNBC cell lines, suggesting a regulatory mechanism independent of hormone receptor status. EZH2 PROTAC treatment reduced FOXM1 protein expression and increased its degradation. In clinical samples, EZH2 mRNA expression tightly correlated with FOXM1 and FOXM1 target genes. Together, this study suggests that EZH2 targeted PROTACs represent a promising avenue of research for the future treatment of BCa, including in the setting of tamoxifen resistance.
Project description:Mass spectrometry-based proteomics was employed to investigate proteolysis targeting chimeras (PROTACs), providing unbiased perspectives on binding, degradation selectivity, and the mechanisms related to efficacy and safety.
Project description:Methotrexate (MTX) is a potent inhibitor of dihydrofolate reductase (DHFR), where is it used as both an antineoplastic and an immunosuppressant. Mechanisms of MTX resistance in cancers include MTX polyglutamylation and upregulation of DHFR. A series of MTX-based PROteolysis TArgeting Chimeras (PROTACs) were designed to selectively degrade human DFHR. These on-target, cell-active PROTACs show proteosome- and E3 ligase-dependent DHFR degradation, selective degradation of DHFR by proteomics, and interpretable structure-activity relationships. Importantly, these PROTACs produced distinct, less-lethal phenotypes compared to MTX, indicating these compounds can complement conventional DFHR enzymatic inhibitors as tool compounds. This chemical probe set, composed of the PROTAC (Diruotrexate), its ester pro-drug (Diruotrexate-ester) and negative control analogs (Diruotrexate-IA1, -IA2), should serve as useful tools for studying one-carbon biochemistry.
Project description:Enhancing mitophagy, a naturally-occurring cellular process for elimination of damaged mitochondria, holds great promise for the intervention of many human diseases. Proteolysis-targeting chimeras (PROTACs) are heterobifunctional molecules that induce ubiquitination and subsequent proteasome-mediated degradation of a target protein through simultaneously binding to the target protein and an E3 ubiquitin ligase. However, the narrow cavity of the proteasome prevents the degradation of mitochondria. Here we show that the E3 ubiquitin ligase MAP3K1, when recruited to the outer mitochondria membrane (OMM) protein TSPO by our PROTAC-designed molecules (termed “mitophagy-enhancing chimeras”, or MECs), induced extensive K63 ubiquitination of TSPO and other OMM proteins, reminiscent of the PINK1-activated Parkin, without triggering proteasome-mediated degradation of TSPO. Aided by NBR1 and Nur77, this increased K63 ubiquitination of OMM proteins triggered mitophagy exclusively for damaged mitochondria, leading to improved mitochondria function and diminished cellular ROS. With the capability to enhance mitophagy at low nanomolar concentrations, MECs effectively inhibited NLRP3 inflammasome activation, abrogated acetaminophen-induced acute liver injury and mitigated high-fat diet-induced obesity in mice. Our work provided a proof-of-concept for developing unconventionally-acting PROTACs to achieve degradation of damaged mitochondria and possibly other organelles.
Project description:Data files associated with the manuscript titled "Development of MDM2-targeting PROTAC for Advancing Bone Regeneration," which is currently under review. This manuscript introduces MDM2-targeting PROTACs customized for application in bone regeneration. We developed MDM2-PROTACs (CL144) that demonstrated potent degradation efficiency and a strong inductive effect on biomineralization. Proteomics analysis was performed on human bone marrow-derived mesenchymal stem cells (hBMSCs) to investigate the degradation selectivity of the compound. Through proteomics database searches, we identified 6,388 proteins, including several differentially expressed proteins (DEPs), many of which are known to interact with MDM2 or play significant roles in the ubiquitin-proteasome system.
Project description:Spinal and bulbar muscular atrophy (SBMA) is a CAG/polyglutamine (polyQ) repeat expansion disorder in which the mutant androgen receptor (AR) protein triggers progressive degeneration of the neuromuscular system in men. As the misfolded polyQ AR is the proximal mediator of toxicity, therapeutic efforts have focused on targeting the mutant protein, but these prior efforts have met with limited success in SBMA patients. Here, we examine the efficacy of proteolysis targeting chimeras (PROTACs), small molecule AR degraders that rapidly and potently promote AR ubiquitination and degradation by the proteasome. We identify ARD-1676 as a PROTAC that clears polyQ AR in an over-expression system, in patient iPSC-derived induced motor neurons and skeletal muscle cells, and in a gene targeted mouse model of disease. Furthermore, we demonstrate that 24-hour treatment with ARD-1676 rescues transcriptional dysregulation in SBMA induced skeletal muscle cells. These data provide evidence of therapeutic efficacy and in vivo target engagement, establishing PROTACs as potential therapeutic agents for the treatment of SBMA.
Project description:Data files associated with the manuscript titled "Development of MDM2-targeting PROTAC for Advancing Bone Regeneration," which is currently under review. This manuscript introduces MDM2-targeting PROTACs specifically designed for applications in bone regeneration. We developed MDM2-PROTACs (CL144) that demonstrated potent degradation efficiency and a strong inductive effect on biomineralization. Proteomics analysis was conducted on HeLa cells overexpressing MDM2 to investigate the degradation selectivity of the compound. From the proteomics database search, we identified 8,353 proteins and observed the downregulation of several ubiquitin ligases and processing proteins, including USP29, USP48, RBX1, and ZNF598, in the HeLa cell experiment.