MED12 mutation activates the tryptophan/kynurenine/AHR pathway to promote growth of uterine leiomyomas
Azna Zuberi, Yongchao Huang, Ariel J. Dotts, Helen Wei, John S. Coon V, Shimeng Liu, Takashi Iizuka, Olivia Wu, Olivia Sotos, Priyanka Saini, Debabrata Chakravarti, Thomas G. Boyer, Yang Dai, Serdar E. Bulun, Ping Yin
Azna Zuberi, Yongchao Huang, Ariel J. Dotts, Helen Wei, John S. Coon V, Shimeng Liu, Takashi Iizuka, Olivia Wu, Olivia Sotos, Priyanka Saini, Debabrata Chakravarti, Thomas G. Boyer, Yang Dai, Serdar E. Bulun, Ping Yin
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Research Article Metabolism Reproductive biology

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

Abstract

Uterine leiomyomas cause heavy menstrual bleeding, anemia, and pregnancy loss in millions of women worldwide. Driver mutations in the transcriptional mediator complex subunit 12 (MED12) gene in uterine myometrial cells initiate 70% of leiomyomas that grow in a progesterone-dependent manner. We showed a distinct chromatin occupancy landscape of MED12 in mutant MED12 (mut-MED12) versus WT-MED12 leiomyomas. Integration of cistromic and transcriptomics data identified tryptophan 2,3-dioxygenase (TDO2) as the top mut-MED12 target gene that was significantly upregulated in mut-MED12 leiomyomas when compared with adjacent myometrium and WT-MED12 leiomyomas. TDO2 catalyzes the conversion of tryptophan to kynurenine, an aryl hydrocarbon receptor (AHR) ligand that we confirmed to be significantly elevated in mut-MED12 leiomyomas. Treatment of primary mut-MED12 leiomyoma cells with tryptophan or kynurenine stimulated AHR nuclear translocation, increased proliferation, inhibited apoptosis, and induced AHR-target gene expression, whereas blocking the TDO2/kynurenine/AHR pathway by siRNA or pharmacological treatment abolished these effects. Progesterone receptors regulated the expression of AHR and its target genes. In vivo, TDO2 expression positively correlated with the expression of genes crucial for leiomyoma growth. In summary, activation of the TDO2/kynurenine/AHR pathway selectively in mut-MED12 leiomyomas promoted tumor growth and may inform the future development of targeted treatments and precision medicine.

Authors

Azna Zuberi, Yongchao Huang, Ariel J. Dotts, Helen Wei, John S. Coon V, Shimeng Liu, Takashi Iizuka, Olivia Wu, Olivia Sotos, Priyanka Saini, Debabrata Chakravarti, Thomas G. Boyer, Yang Dai, Serdar E. Bulun, Ping Yin

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Figure 5

TDO2-mediated Trp metabolism activates the AHR pathway in LM cells.

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TDO2-mediated Trp metabolism activates the AHR pathway in LM cells. (A) ...
(A) AHR nuclear localization (red) was assessed by immunostaining LM cells treated with 200 μM Kyn for 24 hours. Scale bars: 200 μm. DAPI was used for nuclear staining. ImageJ was used to quantify the nuclear mean fluorescence intensity of AHR. (B) ChIP-qPCR assay of AHR binding to the enhancer regions of CYP1A1 and CYP1B1 genes in LM cells treated with Kyn (200 μM) for 90 minutes (n = 5). (C) qPCR of mRNA levels of CYP1A1 and CYP1B1 in LM cells treated with Kyn (200 μM) for 24 hours (n = 4). (D and E) Effects of AHR siRNA (D; n = 5) or AHR antagonist (E; CH223191, 10 μM, n = 7–8) on Kyn-induced CYP1A1 and CYP1B1 gene expression. Ctrl, control; si, siRNA. (F and G) Effects of TDO2 inhibitor (F; 680C91, 10 μM, n = 4) or TDO2 siRNA (G; n = 3) on Trp-induced CYP1A1 and CYP1B1 expression. *P < 0.05, **P < 0.01, ***P < 0.005, ****P < 0.0001 by paired t test (A, C, and G), 1-way (E and F), or 2-way (B and D) ANOVA with Tukey’s multiple-comparison test.