Project description:While ERα+ breast cancer treatment is considered effective, resistance to endocrine therapy is common. Since in therapy-resistance tumors, ERα is still the main driver, alternative therapeutic strategies are needed to disrupt ERα transcriptional activity. In this work, we describe TRIM24 as a key player of the ERα transcriptional complex. TRIM24 interacts with ERα and other well-known ERα-cofactors to facilitate ERα chromatin interactions, and allows for maintenance of active histone marks including H3K23ac and H3K27ac. Consequently, genetic perturbation of TRIM24 abrogates ERα-driven transcriptional programs and reduces tumor cell proliferation capacity. Using a recently-developed PROTAC targeting TRIM24, ERα-driven transcriptional output and growth was blocked, effectively treating not only endocrine-responsive cell lines, but also drug resistant derivates thereof as well as cell line models bearing activating ESR1 point mutations. Finally, using human tumor-derived organoid models, we could show efficacy of TRIM24 PROTAC in the endocrine responsive and resistant setting, with no response in ERα-negative organoids. Overall, our study positions TRIM24 as a central component for integrity and activity of the ERα transcriptional complex, with PROTAC-mediated perturbation of TRIM24 as promising therapeutic avenue in the treatment of primary and endocrine resistance breast cancer.
Project description:While ERα+ breast cancer treatment is considered effective, resistance to endocrine therapy is common. Since ERα is still the main driver in most therapy-resistance tumors, alternative therapeutic strategies are needed to disrupt ERα transcriptional activity. In this work, we position TRIM24 as therapeutic target in endocrine resistance, in its role as key player of the ERα transcriptional complex. TRIM24 interacts with ERα and other well-known ERα-cofactors to facilitate ERα chromatin interactions, and allows for maintenance of active histone marks including H3K23ac and H3K27ac. Consequently, genetic perturbation of TRIM24 abrogates ERα-driven transcriptional programs and reduces tumor cell proliferation capacity. Using a recently-developed degrader targeting TRIM24, ERα-driven transcriptional output and growth was blocked, effectively treating not only endocrine-responsive cell lines, but also drug resistant derivates thereof as well as cell line models bearing activating ESR1 point mutations. Finally, using human tumor-derived organoid models, we could show efficacy of TRIM24 degrader in the endocrine responsive and resistant setting. Overall, our study positions TRIM24 as a central component for integrity and activity of the ERα transcriptional complex, with degradation-mediated perturbation of TRIM24 as promising therapeutic avenue in the treatment of primary and endocrine resistance breast cancer.
Project description:While ERα+ breast cancer treatment is considered effective, resistance to endocrine therapy is common. Since in therapy-resistance tumors, ERα is still the main driver, alternative therapeutic strategies are needed to disrupt ERα transcriptional activity. In this work, we describe TRIM24 as a key player of the ERα transcriptional complex. TRIM24 interacts with ERα and other well-known ERα-cofactors to facilitate ERα chromatin interactions, and allows for maintenance of active histone marks including H3K23ac and H3K27ac. Consequently, genetic perturbation of TRIM24 abrogates ERα-driven transcriptional programs and reduces tumor cell proliferation capacity. Using a recently-developed PROTAC targeting TRIM24, ERα-driven transcriptional output and growth was blocked, effectively treating not only endocrine-responsive cell lines, but also drug resistant derivates thereof as well as cell line models bearing activating ESR1 point mutations. Finally, using human tumor-derived organoid models, we could show efficacy of TRIM24 PROTAC in the endocrine responsive and resistant setting, with no response in ERα-negative organoids. Overall, our study positions TRIM24 as a central component for integrity and activity of the ERα transcriptional complex, with PROTAC-mediated perturbation of TRIM24 as promising therapeutic avenue in the treatment of primary and endocrine resistance breast cancer.
Project description:Conditional overexpression of histone reader Tripartite motif containing protein 24 (TRIM24) in mouse mammary epithelia (Trim24COE) drives spontaneous development of carcinosarcoma tumors, lacking ER, PR and HER2. Human carcinosarcomas or metaplastic breast cancers (MpBC) are a rare, chemorefractory subclass of triple-negative breast cancers (TNBC). Comparison of Trim24COE carcinosarcoma morphology, TRIM24 protein levels and a derived Trim24COE gene signature revealed strong correlation with human MpBC tumors and MpBC xenograft (PDX) models. Global and single-cell tumor profiling revealed Met as a direct oncogenic target of TRIM24, leading to aberrant PI3K/mTOR activation. Pharmacological inhibition of these pathways in primary Trim24COE tumor cells and TRIM24-PROTAC treatment of MpBC PDX tumorspheres revealed the therapeutic potential of targeting TRIM24. Altogether, global expression, single-cell immunophenotyping and mechanistic studies of tumors and MpBC PDX nominated TRIM24-activated c-MET/PI3K/mTOR pathways and TRIM24, which were validated as potential MpBC therapeutic targets.
Project description:Global profiling of tumor expression revealed increased RING-PHD-Bromodomain protein TRIM24 levels in numerous human cancers. Conditional over-expression of Trim24 was sufficient to drive murine mammary tumor development, 70% of which were ER, PR and HER2-negative carcinosarcomas with coexisting malignant epithelial and mesenchymal compartments, offering a unique model of human triple-negative, metaplastic breast cancer (MpBC). Both in vivo and in cellulo, TRIM24 induced EMT, repressing CDH1 and activating EMT factors. Whole exome sequencing of human MpBC tumors and Trim24-driven carcinosarcomas defined a TRIM24-like subclass of MpBC patients with worse overall and relapse-free survival. Among 40 MpBC patients, 43% had robust expression of TRIM24. These studies implicate TRIM24 as a potential biomarker and therapeutic target for a subset of MpBC.
Project description:Abstract Several endocrine therapy (ET) resistance mechanisms for ER-positive (ER+) breast cancer (BC) have been proposed, including acquired ESR1 (ERα gene) mutations. The two most common ESR1 mutations are Y537S and D538G, which give rise to a constitutively active receptor with reduced affinity for agonists and antagonists. The discovery of new effective therapies remains a significant challenge in treating mutated ER+ BC. In this context, Poly (ADP-ribose) polymerase-1 (PARP-1) has captured considerable interest as a target for therapeutic inhibitors in specific types of cancers. Here, we report that crosstalk between PARP-1 and ERα may represent a novel therapeutic approach for ER+ BC. We have demonstrated that the up-regulation of PARP-1 expression, stimulated by 17-β estradiol (E2), was blocked by treatment with fulvestrant (Ful), a potent ERα antagonist, or ESR1 siRNA in ER+ MCF7 and T47D BC cell models that express both wild type ERα and the Y537S mutation, indicating that ERα regulates the expression of PARP-1. In addition, ERα-mediated transcriptional activity depended on PARP-1 activity in these models, as confirmed by ERα target gene expression and ERE reporter gene analyses +/- niraparib (Nira). Notably, PARP-1 modulates the estrogen-dependent genomic binding of ERα and FoxA1, which play a crucial role in the proliferation of ER+ BC. We also showed that PARP-1 inhibition prevented proliferation and cell cycle activities of ERα WT and ERα Y537S cells upon ERα activation. In vivo, Nira and lasofoxifene (Laso), an ERα antagonist, significantly reduced primary tumor growth versus vehicle, both as single agents and in combination. Moreover, RNA-seq analyses demonstrated the downregulation of ERα signaling in the mammary glands of mice treated with Nira versus Vehicle. Our results provide novel insights into the molecular events through which PARP-1 may serve as a more comprehensive therapeutic approach to target ET BC resistance in women with advanced ER+ BC.