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MED12 mutation activates the tryptophan/kynurenine/AHR pathway to promote growth of uterine leiomyomas

ABSTRACT: Uterine leiomyoma (LM) is the most common tumor in women. Estrogen and progesterone, via their receptors ERα and PR, play essential roles in LM growth. Mediator complex subunit 12 (MED12) mutations occur in 70% of all LM and are thought to drive tumor growth in a steroid hormone-dependent manner; however, the mechanisms remain unclear. Here, we performed ChIP-seq (ERα, PR, and MED12) and RNA-seq on LM expressing mutant MED12 (mut-MED12) or wild-type MED12 and matched myometrium. Mut-MED12 altered PR and chromatin interaction landscapes, with significant PR-binding site loss in proximal promoter regions in mut-MED12 LM. Integration of cistrome and transcriptome data identified tryptophan 2,3-dioxygenase (TDO2) as a PR and MED12 target gene, which was aberrantly upregulated in mut-MED12 LM. Kynurenine, the catabolic product of TDO2, was significantly elevated in mut-MED12 LM. Tryptophan or kynurenine treatment of primary LM cells activated the aryl hydrocarbon receptor (AHR) pathway, increased cell proliferation, and inhibited apoptosis; blocking the TDO2-kynurenine-AHR pathway by siRNA knockdown or pharmacologic inhibition abolished these effects. Mut-MED12 LM cells showed higher sensitivity to these treatments. These findings suggest that activation of the TDO2-kynurenine-AHR pathway in mut-MED12 LM induces tumor growth, and may inform the development of targeted treatments and precision medicine in LM.

ORGANISM(S): Homo sapiens

PROVIDER: GSE204968 | GEO | 2023/05/01

REPOSITORIES: GEO

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Project description:Understanding the mechanisms of host macrophage responses to M. tuberculosis (M.tb.) is essential for uncovering potential avenues of intervention to boost host resistance to infection. Macrophage transcriptome profiling revealed M.tb. infection strongly induced expression of several enzymes controlling tryptophan (Trp) catabolism. This included indole 2,3-dioxygenase 1 (IDO1) and tryptophan 2,3-dioxygenase (TDO2), which catalyze the rate-limiting step in the kynurenine pathway, producing ligands for the aryl hydrocarbon receptor (AHR). The AHR and heterodimeric partners AHR nuclear translocator (ARNT) and RELB are robustly expressed, and AHR and RELB levels further increased during infection. Infection enhanced AHR/ARNT and AHR/RELB DNA binding, and stimulated expression of AHR target genes, including that encoding the inflammatory cytokine IL1beta. AHR target gene expression was further enhanced by exogenous kynurenine, and exogenous Trp, kynurenine or synthetic agonist indirubin reduced mycobacterial viability. Comparative expression profiling revealed that AHR ablation diminished expression of numerous genes implicated in innate immune responses, including several cytokines. Notably, AHR depletion reduced expression of IL23A and IL12B transcripts, which encode subunits of interleukin 23 (IL23), a macrophage cytokine that stimulates production of IL22 by innate lymphoid cells. The AHR directly induced IL23A transcription in human and mouse macrophages through near-upstream enhancer regions. Taken together, these findings show that AHR signaling is strongly engaged in Mtb-infected macrophages, and has widespread effects on innate immune responses. Moreover, they reveal a cascade of AHR-driven innate immune signaling, as IL1B (IL-1β) and IL23 stimulate T cell subsets producing IL22, another direct target of AHR transactivation. Gene expression profiling of Mtb-infected THP-1 monocytic cells following siRNA-mediated Aryl hydrocarbon receptor (AHR) knockdown.

Project description:Intratumoral microglia and MΦ constitute up to 70% of the tumor mass of high-grade gliomas (HGG) with profound impact on hallmarks of malignancy such as angiogenesis and immunosuppression. The dynamics and functional states of intratumoral myeloid cells during tumor progression and the molecular mechanisms controlling them are poorly understood. Here we define homeostatic and antigen-presenting myeloid cellular states in experimental and human HGG by longitudinal single-cell RNA-sequencing and combined transcriptome and proteome profiling. During glioma progression, myeloid cells gradually shift from a homeostatic to a tumor-associated effector state. We show that these dynamics are under strict control by early changes in resident microglia and the tumor genotype: In gliomas with mutations in isocitrate dehydrogenase (IDH), a disease-defining driver mutation, differentiation of invaded myeloid cells was blocked resulting in an immature, immunosuppressive phenotype. In late-stage IDH-mutant gliomas, monocyte-derived MΦ drive a tolerogenic remodeling of the glioma microenvironment thus preventing T-cell response. We define the molecular mechanism responsible for the tumor genotype-dependent education of infiltrating MΦ to be causally related to an enzymatically enhanced tryptophan catabolism via TDO2, resulting in the production of kynurenine, an endogenous ligand of the aryl hydrocarbon receptor (AHR). TDO2 activation further induces an amino acid starvation response triggering the import of exogenous tryptophan by intratumoral MΦ via LAT1-CD98. We here provide evidence that paracrine R-2-HG and tryptophan are critically involved in the differentiation and activation of monocyte-derived MΦ and that the previously observed altered amino acid metabolism in IDHmut gliomas is also responsible for shaping an immunosuppressive tumor microenvironment through maintenance of this complex metabolic axis. We further show that this regulatory metabolic network is particularly active in infiltrating MΦ because of their distinct expression profile that constitutes an immune subset-specific metabolic vulnerability. Consequently, the immunosuppressive phenotype in IDH-mutant glioma models was reversed by pharmacological inhibition of LAT1-CD98 or AHR. Thus, we provide evidence for a tumor genotype-dependent, dynamic network of resident and recruited intratumoral myeloid cells that shape the immune microenvironment of IDH-mutant HGG through pleiotropic interaction with the tumor metabolome and identify tryptophan metabolism as a viable therapeutic target for the immunotherapy of IDH-mutant tumors.

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MED12 mutation activates the tryptophan/kynurenine/AHR pathway to promote growth of uterine leiomyomas

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