Ping Yin

Therapeutic targeting of the tryptophan-kynurenine-aryl hydrocarbon receptor pathway with apigenin in MED12-mutant leiomyoma cells

Approximately 77.4% of uterine leiomyomas carry MED12 gene mutations (mut-MED12), which are specifically associated with strikingly upregulated expression and activity of the tryptophan 2,3-dioxygenase (TDO2) enzyme, leading to increased conversion of tryptophan to kynureine. Kynurenine increases leiomyoma cell survival by activating the aryl hydrocarbon receptor (AHR). We used a leiomyoma-relevant model, in which a MED12 Gly44 mutation was knocked in by CRISPR in a human uterine myometrial smooth muscle (UtSM) cell line, in addition to primary leiomyoma cells from 26 patients to ascertain the mechanisms responsible for therapeutic effects of apigenin, a natural compound. Apigenin treatment significantly decreased cell viability, inhibited cell cycle progression, and induced apoptosis preferentially in mut-MED12 versus wild-type primary leiomyoma and UtSM cells. Apigenin not only blocked AHR action but also decreased TDO2 expression and kynurenine production, preferentially in mut-MED12 cells. Apigenin did not alter TDO2 enzyme activity. TNF and IL-1β, cytokines upregulated in leiomyoma, strikingly induced TDO2 expression levels via activating the NF-κB and JNK pathways, which were abolished by apigenin. Apigenin or a TDO2 inhibitor decreased UtSM cell viability induced by TNF/IL-1β. We provide proof-of-principle evidence that apigenin is a potential therapeutic agent for mut-MED12 leiomyomas.

Stearoyl–coenzyme A desaturase enhances cell survival in human uterine leiomyoma

Stearoyl-CoA desaturase (SCD1) is an enzyme that catalyzes the conversion of saturated delta-9 fatty acids to monounsaturated fatty acids. SCD1 is highly expressed in various cancers and facilitates cancer cell survival, tumor growth, and metastasis. This study aimed to assess SCD1 expression and function in uterine leiomyoma and matched myometrial tissue and evaluate the impact of SCD1 inhibition on leiomyoma cell viability and apoptosis. Gene set enrichment analysis was performed to determine whether lipid metabolism pathways are dysregulated in leiomyoma. To assess the function of SCD1, primary leiomyoma and myometrial cells, as well as a CRISPR-engineered leiomyoma-relevant MED12 mutant human uterine smooth muscle (UtSM) cell line, were treated with SCD1 small interfering RNA or a small molecule inhibitor of SCD1, CAY10566. Cell viability and apoptosis assays, real-time quantitative polymerase chain reaction, and immunoblot analyses were performed to evaluate cell function in response to treatment. Leiomyoma and myometrial tissues were obtained from premenopausal individuals designated female at birth (n = 30) undergoing myomectomy or hysterectomy. SCD1 inhibition by small interfering RNA and CAY10566 treatment. Messenger RNA (mRNA) and protein levels and cell viability and apoptosis. Gene set enrichment analysis revealed that the cholesterol homeostasis pathway was significantly different in leiomyoma vs. adjacent myometrial tissues. Among the genes in this pathway, SCD1 mRNA levels were found to be significantly higher in leiomyoma than in matched myometrium. SCD1 inhibition by small interfering RNA or CAY10566 decreased antiapoptotic BCL2 mRNA and protein levels and cell viability in primary leiomyoma but not myometrial cells. SCD1 protein levels were significantly higher in the mutant MED12 UtSM cell line than in the wild-type MED12 UtSM cell line. CAY10566 treatment specifically decreased cell viability and increased apoptosis in mutant MED12 UtSM cells, with increased protein levels of cleaved caspase 3, cleaved PARP, and DDIT3 in mutant MED12 UtSM but not in wild-type MED12 UtSM cells. SCD1, an enzyme involved in lipid homeostasis, may play an important role in promoting leiomyoma growth and represents a novel target for the treatment of leiomyoma.