Project description:MDM2 inhibitor remarkably induced biomineralization in hDPSCs but it remained the problem that p53 activation is insufficient due to MDM2-p53 autoregulatory feedback loop. To overcome the limitation of the MDM2 inhibitors, we applied proteolysis targeting chimera (PROTAC), a technology that degrades a protein of interest (POI) by intracellular ubiquitin-proteasome system. Hence, we propose a strategy to induce hard tissue regeneration by MDM2-targeting PROTAC technology. We selected Nutlin-3 of POI ligand among various MDM2 inhibitors based on the screening process, and the selected CRBN of E3 ligase ligand. The MDM2-PROTAC synthesis platform was designed by each ligand combination. By performing the degradation test for selected compounds, we evaluated the characteristics of the developed MDM2 PROTAC such as the maximal degradation concentration (DCmax), the half of maximal degradation concentration (DC50), and half-lifetime. To investigate gene expression profiling of MDM2-targeting small molecules, we conducted RNA-sequencing under MDM2 PROTAC and Nutlin-3 (POI ligand) treated conditions. We not only confirmed a robust effect on biomineralization by MDM2-targeting small molecules but also demonstrated the potent osteogenic differentiation ability of MDM2 PROTAC when compared to an MDM2 inhibitor. MDM2-PROTAC significantly increased mRNA levels of osteogenic differentiation marker genes. Also, the significant bone generation effect of MDM2 PROTAC was validated in an ovariectomy (OVX)-induced osteoporosis animal model. Through these results, it is expected that a new therapeutic modality for hard tissue regeneration will be possible, and the application range of the PROTAC system can be expanded.
Project description:PTK6 PROTAC treatment of T47D breast cancer cells were analyzed with mass spectrometry for determining PTK6 PROTAC specificity and global proteomic changes.
Project description:The RAF family kinases function in the RAS-ERK pathway to transmit signals from activated RAS to the downstream kinases MEK and ERK. This pathway regulates cell proliferation, differentiation, and survival enabling mutations in RAS and RAF to act as potent drivers of human cancers. Drugs targeting the prevalent oncogenic mutant BRAFV600E have shown great efficacy in the clinic but long-term effectiveness is limited by resistance mechanisms that often exploit the dimerization-dependent process by which RAF kinases are activated. Here, we investigated a proteolysis targeting chimera (PROTAC) approach to BRAF inhibition. The most effective PROTAC termed P4B displayed superior specificity and inhibitory properties relative to non-PROTAC controls in BRAFV600E cell lines. In addition, P4B displayed utility in two cell lines harboring alternate BRAF mutations that impart resistance to conventional BRAF inhibitors. This work provides a rationale for optimizing the drug-like properties of P4B to enable proof of concept studies in vivo.
Project description:Proteolysis targeting chimeras (PROTACs) are bifunctional molecules that induce selective protein degradation by linking an E3 ubiquitin ligase enzyme to a target protein. This approach allows scope for targeting “undruggable” proteins and several PROTACs have reached the stage of clinical candidates. However, the roles of cellular transmembrane transporters in PROTAC uptake and efflux remain underexplored. Here, we utilized transporter-focused genetic screens to identify the ATP binding cassette transporter ABCC1/MRP1 as a key PROTAC resistance factor. Unlike the previously identified inducible PROTAC exporter ABCB1/MDR1, ABCC1 is highly expressed among cancers of various origins and constitutively restricts PROTAC bioavailability. Moreover, in a genome-wide PROTAC resistance screen, we identified candidates involved in processes such as ubiquitination, mTOR signaling and apoptosis as genetic factors involved in PROTAC resistance. In summary, our findings reveal ABCC1 as a crucial constitutively active efflux pump limiting PROTAC efficacy in various cancer cells, offering insights for overcoming drug resistance.
Project description:Native mass spectrometry enabled direct confirmation of PROTAC-mediated targeting of BCL-xL, while auxiliary activation methods dissected the disassembly of the ternary complexes, offering mechanistic insights.
Project description:Androgen receptor (AR) signaling remains a key driver of castration-resistant prostate cancer, with AR splice variants like AR-V7 mediating resistance to second-generation antiandrogens. Targeting the AR N-terminal domain (NTD) offers a strategy to bypass ligand-binding domain-mediated resistance. We developed a VHL-based (ITRI-90) and a CRBN-based (ITRI-148) PROTAC degrader capable of targeting AR and AR-V7 via NTD. These compounds demonstrate potent antitumor activity towards castration-resistant and enzalutamide resistant xenograft models. Transcriptomic analyses confirm robust suppression of AR and AR-V7 target genes by ITRI-148 in VCaP cells. The transcriptomic effects of these AR-NTD degraders in enzalutamide-resistant C4-2B/MDVR cells closely mirror that of AR knockdown.
Project description:Bromodomain extraterminal protein (BETP) inhibitors transcriptionally repress oncoproteins which undermines the growth and survival of AML cells. However, BETi treatment causes accumulation of BETPs, associated with reversible binding and incomplete inhibition of BRD4, which potentially compromises the activity of BETi in AML cells. Unlike BETi, BET-PROTAC (proteolysis-targeting chimera) ARV-825 recruits and utilize an E3-ubiquitin ligase to effectively degrade BETPs in AML cells. BET-PROTACs induce more apoptosis than BETi of mtRUNX1 AML cells. BET-PROTAC treatment induced more perturbations in the mRNA and protein expressions than BETi. It was noted that treatment with BETi or BET-PROTAC caused significant and sustained depletion of RUNX1 in AML cells. We also determined the effects of global depletion of RUNX1 in mtRUNX1 expressing AML OCI-AML5 cells. We observed an overlap in the signature of RUNX1 knockdown by shRNA with that of OTX015 and ARV-825 in OCI-AML5 cells.
Project description:The role of signal transducer and activator of transcription protein 3 (STAT3) in AKI remains controversial. Our study demonstrated an upregulation of total STAT3 protein in AKI mouse models induced by cecal ligation and puncture (CLP) or ischemia-reperfusion (I/R), correlating with patient biopsy results. This increase may be attributed to histone H3K27 acetylation. STAT3 knockout in renal tubular epithelial cells significantly reduced AKI injury and inflammation in mice. Mechanistically, STAT3 induces the transcription of tripartite motif-containing protein 21 (TRIM21), triggering a cascade that activates gasdermin D (GSDMD), resulting in pyroptosis. Administration of the novel proteolysis-targeting chimera (PROTAC) compound E034, which selectively targets STAT3 for ubiquitination and degradation, significantly alleviated renal injury in a low-dose, single-dose regimen, underscoring its substantial therapeutic potential with infrequent dosing requirements. In the context of renal injury, PROTAC emerges as a promising modality by specifically targeting the STAT3/TRIM21/GSDMD axis, which our study has identified as a potential therapeutic target, thereby potentially endowing novel and clinically significant therapeutic strategies.