Mediator kinase inhibition drives myometrial stem cell differentiation and the uterine fibroid phenotype through super-enhancer reprogramming

Area of Science:

• Reproductive biology
• Cancer biology
• Molecular medicine

Background:

• Uterine fibroids (UFs) are common gynecological tumors originating from myometrial stem cells (MM SCs).
• MED12 gene mutations are primary drivers of UF development, disrupting Mediator complex kinase activity.
• The precise mechanism by which Mediator kinase disruption leads to MM SC transformation into UF stem cells is not fully understood.

Purpose of the Study:

• To investigate the role of CDK8/19 kinase activity in MM SC differentiation.
• To elucidate how inhibiting CDK8/19 impacts molecular pathways relevant to UF formation.
• To explore the transcriptomic and epigenomic changes associated with CDK8/19 inhibition in MM SCs.

Main Methods:

• Pharmacologic inhibition of CDK8/19 in MM SCs.
• Analysis of myogenic differentiation pathways.
• Assessment of molecular phenotypes, including oncogenic growth and extracellular matrix (ECM) production.
• Transcriptomic and epigenomic profiling to identify molecular alterations.

Main Results:

• CDK8/19 inhibition in MM SCs removed a differentiation barrier, promoting an altered pathway.
• This altered pathway exhibited molecular phenotypes characteristic of UFs, such as increased oncogenic growth and ECM production.
• Transcriptomic changes, including epigenomic alterations and super-enhancer reprogramming, were observed, recapitulating those in MED12-mutant UFs.

Conclusions:

• CDK8/19 plays a critical role in regulating MM SC differentiation and preventing transformation.
• Inhibition of CDK8/19 can induce UF-like molecular characteristics in MM SCs.
• These findings offer novel insights into the biological mechanisms underlying UF development and potential therapeutic targets.