Multi-omic Analysis of Uterine Leiomyomas in Self-Described Black and White Women: Molecular Insights into Health Disparities

Background Black women are at an increased risk to develop uterine leiomyomas (ULMs) and to experience worse disease prognosis compared to White women. Epidemiological and molecular factors have been identified as underlying these disparities, but there remains a paucity of deep, multi-omic analysis investigating molecular differences in ULMs from Black and White patients. Objective To identify molecular alterations within ULM tissues correlating with patient race by multi-omic analyses of ULMs collected from cohorts of Black and White women. Study Design We performed multi-omic analysis of ULMs from Black (42) and White (47) women undergoing hysterectomy for symptomatic uterine leiomyomata. Our analysis also included application of orthogonal methods to evaluate fibroid biomechanical properties, such as second harmonic generation microscopy, uniaxial compression testing, as well as sheer wave ultrasonography analyses. Results We found a greater proportion of mediator complex subunit 12 (MED12) mutant ULMs from Black women (>35% increase, Mann Whitney U p = 7E-4). MED12 mutant tumors exhibited elevated abundance of extracellular matrix proteins, including several collagen isoforms, involved in regulation of the core matrisome. Histological analysis of tissue fibrosis using trichrome staining and secondary harmonic generation microscopy confirmed that MED12 mutant tumors are more fibrotic than MED12 wildtype tumors. Using Sheer Wave ultrasonography in a prospectively collected cohort, Black patients had fibroids that were firmer when compared to White patients, even when similar in size. These analyses also uncovered expression quantitative trait loci (eQTL) associated with altered allele frequencies in African and European populations that correlated with differential abundance of several proteins in ULM that are independent of MED12 mutational status, including multiple eQTL mapping to tetratricopeptide repeat protein 38. Conclusions Our study shows that Black women have a higher prevalence of ULMs harboring mutations in MED12 and that this mutational status correlates with increased tissue fibrosis in comparison with wildtype ULMs. Our study provides insights into molecular alterations underlying racial disparities in ULMs and improves our understanding of the molecular etiology underlying ULM development within these populations.