{"doi":"10.1002/ctm2.1672","title":"Synergistic inhibition of progesterone receptor‐A/B signalling by simvastatin and mifepristone in human uterine leiomyomas","abstract":"Dear Editor, We examined the interaction between simvastatin (SIM) and the progesterone pathway for the treatment of fibroids using human tissue and explored cellular mechanisms by which SIM, a hydroxymethylglutaryl-CoA reductase inhibitor, and mifepristone (MIF), a progesterone receptor (PR) antagonist, act synergistically to inhibit fibroid growth. Using patient-derived primary leiomyoma cells, immortalized fibroid (human immortalized leiomyoma [HuLM]) cells, and fibroids taken from a xenograft mouse model and patient-derived surgical specimens in an ongoing phase II randomized controlled trial (RCT) of SIM versus placebo, we investigated mechanistic effects of SIM on PR expression, fibroid cell proliferation, and downstream signalling. Leiomyomas (fibroids) are common benign smooth muscle tumours of the uterus that participate in signalling pathways related to extracellular matrix (ECM) remodelling and cell proliferation.1 Leiomyoma cells express PRs whose stimulation increases cellular proliferation.2, 3 SIM inhibits fibroid growth by impeding proliferation pathways and disrupting mechanotransduction, the cellular sensing of and response to contractile stress.4 However, it remains unknown whether SIM acts on these pathways in a PR-dependent fashion. To explore whether SIM affects the progesterone system in human leiomyomas in vivo, we immunohistochemically stained pPR-A/B from patients with leiomyomas enrolled in an ongoing RCT of placebo versus SIM (Figure 1A). We observed suppression of pPR-A/B expression in all four subjects treated with SIM (Figure 1B,C). We next determined whether SIM affects leiomyoma proliferation via a progesterone-dependent mechanism. We treated primary uterine leiomyoma cells with 100 nM progesterone (P4) and SIM alone or in combination. Using the MTT proliferation assay, we observed significantly elevated proliferation at 48 h compared to vehicle control, with diminished proliferation by 48 h, consistent with prior work5, 6 (Figure S1A). We treated primary leiomyoma cells with increasing doses of SIM and observed a dose-dependent decrease in proliferating cell nuclear antigen (PCNA) protein expression, (cellular proliferation marker) (Figure S1B). We performed a patient-derived xenograft leiomyoma mouse model study of SIM treatment to observe the effects of SIM on PR expression in xenografted mice.7, 8 Treatment with SIM led to decreased PR expression in vivo (Figure 2A). We corroborated these data with immunofluorescence in human primary leiomyoma cells, noting a similar pattern (Figure 2B). We quantified the expression of PRs A and B (PR-A/PR-B) using this paradigm, observing a dose-dependent decrease in total and phosphorylated PR-A/PR-B with increasing SIM concentrations (Figure 2C,D). To investigate the downstream signalling of SIM on primary leiomyoma cells, we performed Western blots for key proliferation-related proteins in SIM-treated cells. We observed a dose-dependent decrease in pERK1/2/ERK1/2, pJNK1/2/JNK1/2, pAKT/AKT and pmTOR1/mTOR1 with increasing SIM doses (Figure 3A–D). We noted decreased PGMCR1, a PR interacting partner, with increasing concentrations of SIM (Figure 3E). SIM downregulated PR in leiomyoma cells in a dose-dependent fashion using a luciferase reporter assay (Figure 3F). Leiomyoma cells interact with their surrounding ECM.4, 9 Specifically, they overexpress Integrin β1 and participate in mechanotransduction signalling.9 SIM decreases the expression of integrin β1 and downstream signalling via focal adhesion kinase (FAK), leading to increased cellular contractility and increased ECM stiffness in primary leiomyoma cells.4 To determine whether SIM affects the leiomyoma mechanotransduction not only at the level of intracellular FAK but also via extracellular proteins, we measured levels of proteins important in ECM and mechanotransduction dynamics in primary leiomyoma cells treated with SIM. Consistently, we found that SIM dose-dependently downregulated collagen 1A, v","journal":"Clinical and Translational Medicine","year":2024,"id":496946,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":0,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9577,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2024-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":477478,"name":"Gregory W. Kirschen","orcid":"0000-0003-1371-8137","position":1,"is_corresponding":false},{"id":498106,"name":"Mariko Miyashita‐Ishiwata","orcid":"0000-0001-8586-7073","position":2,"is_corresponding":false},{"id":397356,"name":"Malak El Sabeh","orcid":"0000-0002-7556-2900","position":3,"is_corresponding":false},{"id":405226,"name":"Mostafa A. Borahay","orcid":"0000-0002-0554-132X","position":4,"is_corresponding":false},{"id":391203,"name":"Sadia Afrin","orcid":"0000-0001-5063-9900","position":0,"is_corresponding":true}],"reference_count":9,"raw_metadata":null,"created_at":"2026-07-19T02:09:30.779495Z","pmid":"38649749","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}