Project description:Why some tumors remain indolent and others progress to clinical relevance remains a major unanswered question in cancer biology. Interferon signaling in nascent tumors, mediated by STAT1, is a critical step through which the surveilling immune system can recognize and destroy developing tumors. Herein, we have identified an interaction between the progesterone receptor (PR) and STAT1 in breast cancer cells. This interaction inhibited efficient interferon-induced STAT1 phosphorylation, as we observed a decrease in phospho-STAT1 in response to interferon treatment in PR-positive breast cancer cell lines. This phenotype was further potentiated in the presence of PR ligand. In human breast cancer samples, PR-positive tumors exhibited lower levels of phospho-STAT1 as compared to their PR-negative counterparts, indicating that this phenotype translates to human tumors. Breast cancer cells lacking PR exhibited higher levels of interferon-stimulated gene (ISG) RNA, the transcriptional endpoint of interferon activation, indicating that unliganded PR alone could decrease transcription of ISGs. Moreover, the absence of PR led to increased recruitment of STAT1, STAT2 and IRF9 (key transcription factors necessary for ISG transcription) to ISG promoters. These data indicate that PR, both in the presence and absence of ligand, attenuates interferon-induced STAT1 signaling, culminating in significantly abrogated activation of genes transcribed in response to interferons. PR-positive tumors may use downregulation of STAT1-mediated interferon signaling to escape immune surveillance, leading to the development of clinically relevant tumors. Selective immune evasion of PR-positive tumors may be one explanation as to why over 65% of breast cancers are PR-positive at the time of diagnosis.
Project description:The goal of this study is to analyse whether ER-/PR+ breast tumors could be transcriptionally different from ER+/PR+ and/or from triple negative breast tumors
Project description:Major roadblocks to developing effective progesterone receptor (PR)-targeted therapies in breast cancer include the lack of highly-specific PR modulators, a poor understanding of the pro- or anti-tumorigenic networks for PR isoforms and ligands, and an incomplete understanding of the cross talk between PR and estrogen receptor (ER) signaling. Through genomic analyses of xenografts treated with various clinically-relevant ER and PR-targeting drugs, we describe how the activation or inhibition of PR dictates distinct ER and PR chromatin binding and differentially reprograms estrogen signaling, resulting in the segregation of transcriptomes into separate PR agonist and antagonist-mediated groups. These findings address an ongoing controversy regarding the clinical utility of PR agonists and antagonists, alone or in combination with tamoxifen, for breast cancer management. Genomic analyses of the two PR isoforms, PRA and PRB, indicate that these isoforms bind distinct genomic sites and interact with different sets of co-regulators to differentially modulate gene expression as well as pro- or anti-tumorigenic phenotypes. Of the two isoforms, PRA inhibited gene expression and ER chromatin binding significantly more than PRB. Of note, the two isoforms reprogrammed estrogen activity to be either pro or anti-tumorigenic. In concordance to the in-vitro observations, differential gene expression was observed in PRA and PRB-rich patient tumors and importantly, PRA-rich gene signatures had poorer survival outcomes. In support of antiprogestin responsiveness of PRA-rich tumors, gene signatures associated with PR antagonists, but not PR agonists, predicted better survival outcomes. This differential of better patient survival associated with PR antagonists versus PR agonists treatments was further reflected in the higher anti-tumor activity of combination therapies of tamoxifen with PR antagonists and modulators. Knowledge of various determinants of PR action and their interactions with estrogen signaling to differentially modulate breast cancer biology should serve as a guide to the development of biomarkers for patient selection and translation of PR-targeted therapies to the clinic.
Project description:Major roadblocks to developing effective progesterone receptor (PR)-targeted therapies in breast cancer include the lack of highly-specific PR modulators, a poor understanding of the pro- or anti-tumorigenic networks for PR isoforms and ligands, and an incomplete understanding of the cross talk between PR and estrogen receptor (ER) signaling. Through genomic analyses of xenografts treated with various clinically-relevant ER and PR-targeting drugs, we describe how the activation or inhibition of PR differentially reprograms estrogen signaling, resulting in the segregation of transcriptomes into separate PR agonist and antagonist-mediated groups. These findings address an ongoing controversy regarding the clinical utility of PR agonists and antagonists, alone or in combination with tamoxifen, for breast cancer management. Additionally, the two PR isoforms PRA and PRB, bind distinct genomic sites and interact with different sets of co-regulators to differentially modulate estrogen signaling to be either pro- or anti-tumorigenic. Of the two isoforms, PRA inhibited gene expression and ER chromatin binding significantly more than PRB. Differential gene expression was observed in PRA and PRB-rich patient tumors and importantly, PRA-rich gene signatures had poorer survival outcomes. In support of antiprogestin responsiveness of PRA-rich tumors, gene signatures associated with PR antagonists, but not PR agonists, predicted better survival outcomes. This better patient survival associated with PR antagonists versus PR agonists treatments was further reflected in the higher anti-tumor activity of combination therapies of tamoxifen with PR antagonists and modulators. The study suggests that distinguishing common effects observed due to concomitant interaction of another receptor with its ligand (agonist or antagonist) from unique isoform and ligand-specific effects will guide the development of biomarkers for patient selection and translation of PR-targeted therapies to the clinic.
Project description:The ability of neural stem cells (NSCs) to switch between quiescence and proliferation is crucial for brain development and homeostasis. Increasing evidence suggest that variants of histone lysine methyltransferases including KMT5A are associated with neurodevelopmental disorders. However, the function of KMT5A/Pr-set7/SETD8 in the central nervous system is not well established. Here, we show that Drosophila Pr-Set7 is a novel regulator of NSC reactivation. Loss-of-function of pr-set7 causes a delay in NSC reactivation and loss of H4K20 monomethylation in the brain. Through NSC-specific in vivo profiling, we demonstrate that Pr-set7 binds to the promoter region of cyclin dependent kinase 1 (cdk1) and Wnt pathway transcriptional co-activator earthbound1/jerky (ebd1). Further validation indicates that Pr-set7 is required for the expression of cdk1 and ebd1 in the brain. Similar to Pr-set7, Cdk1 and Ebd1 promote NSC reactivation. Moreover, Cdk1 upregulates the Ebd1 levels in NSCs, while Ebd1 appears to downregulate Cdk1 expression, suggesting a negative feedback regulation. Finally, overexpression of Cdk1 and Ebd1 significantly suppressed NSC reactivation defects observed in pr-set7-depleted brains. Therefore, Pr-set7, the sole H4K20 methyltransferase, promotes NSC reactivation through regulating Wnt signaling and cell-cycle progression. Given the conservation of Pr-set7, our findings may contribute to the understanding of mammalian KMT5A/PR-SET7/SETD8 in NSC proliferation and associated neurodevelopmental disorders.
Project description:Hormone receptor (HR) positive breast cancer, defined by expression of estrogen (ER) and/or progesterone (PR) receptor expression, is the most commonly diagnosed type of breast cancer. PR alters the transcriptional landscape to support tumor growth in concert with or independent of ER. Understanding the mechanisms regulating PR function are critical to developing new strategies to treat HR+ breast cancer. O-GlcNAc is a post-translational modification responsible for nutrient sensing that fine tunes protein function. We have previously reported O-GlcNAcylation on PR. Although PR is heavily post translationally modified, primarily through phosphorylation, specific sites of O-GlcNAcylation on PR, and how they regulate PR action, have not been investigated. Using established PR-expressing breast cancer cell lines, we mapped the sites of O-GlcNAcylation on PR. RNA-sequencing revealed site-specific O-GlcNAcylation of PR is critical for ligand-independent suppression of interferon signaling, a regulatory function of PR previously studied in our lab. Furthermore, O-GlcNAcylation of PR enhances PR-driven tumor growth in vivo. We have delineated one mechanism regulating PR function in breast cancer that impacts tumor growth, and provided additional insight into the mechanism through which PR attenuates interferon signaling.
Project description:Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) patients with the C9orf72 mutation show predominantly cytoplasmic aggregates of poly-GR and poly-PR proteins that are acutely toxic in various model systems. To identify the molecular mediators of neurotoxicity of poly-GR/PR, we analyzed their interactomes in primary neurons. GFP-(GR)149 and (PR)175-GFP preferentially interacted with RNA-binding proteins, including stress granule-associated and nucleolar proteins, as well as ribosomes. Overexpression of the poly-GR/PR interactors Staufen 1/2 (STAU1/2) and YBX1 led to cytoplasmic aggregation of poly-GR/PR into large stress granule-like inclusions, while the poly-GR/PR interactor nucleophosmin (NPM1) recruited poly-GR into the nucleolus. In addition, poly-PR expression reduced ribosome levels and translation, which is consistent with the widespread reduction of synaptic proteins detected by proteomics. Surprisingly, only GFP-(GR)53, but not GFP-(GR)149, localized to the nucleolus and reduced ribosome levels and translation in neurons, suggesting impaired ribosome biogenesis is driving the acute toxicity commonly observed in vitro. In C9orf72 patient brains, we detected co-aggregation of poly-GR/PR inclusions with ribosomes, but not stress granules. Partial sequestration of ribosomes may chronically impair protein synthesis and contribute to C9orf72 ALS/FTD pathogenesis.
Project description:An intronic GGGGCC repeat expansion in C9orf72 is a common genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia. The repeats are transcribed in both sense and antisense directions to generate distinct dipeptide repeat proteins, of which poly(GA), poly(GR) and poly(PR) have been implicated in contributing to neurodegeneration. Poly(PR) binding to RNA may contribute to toxicity, but analysis of poly(PR)-RNA binding on a transcriptome-wide scale has not yet been carried out. We therefore performed crosslinking and immunoprecipitation (CLIP) analysis in human cells to identify the RNA binding sites of poly(PR). We found that poly(PR) binds to nearly 600 RNAs, with the sequence GAAGA enriched at the binding sites. In vitro experiments showed that poly(GAAGA) RNA binds poly(PR) with higher affinity than control RNA and induces phase-separation of poly(PR) into condensates. These data indicate that poly(PR) preferentially binds to poly(GAAGA)-containing RNAs, which may have physiological consequences.