Compressive Force Induces Differential Gene and Protein Expression in Uterine Fibroids.

Objective: To study how compressive forces influence fibroid and myometrial cells. Our work aimed to identify proteins and signaling pathways that are altered in fibroids in response to compressive forces.

Design: Laboratory-based SUBJECTS: Patient-matched fibroid and myometrial cells were isolated from 5 women undergoing hysterectomy or myomectomy for the treatment of uterine fibroids. Only samples from women who had not had hormonal modulation within three months of surgery were used for this study. An embedded spheroid model was developed to model the fibroid tissue and provide a cushion that would help with the distribution of compressive force.

Exposure: Weights, 0 or 6.4 mmHg, were added on top of an agarose cushion. Spheroids were cultured for seven days.

Main outcome measures: Histological evaluation, RNA-sequencing (n=5), and proteomics characterization (n=3). Paired multi-test t-tests were performed for statistical analysis. Differentially expressed genes (DEGs) were considered clinically relevant if the same genes were also significantly differentially expressed in at least one of the four existing fibroid and myometrium RNA-sequencing datasets.

Results: A total of 61 clinically relevant DEGs were identified between cell types that were only differentially expressed when the spheroids were under compression. This included EPHB1 which encodes ephrin signaling receptor EphB1; it was upregulated log2 fold-change of 2.81 in fibroid cells (q=5.35×10^-3). Compression led to the enrichment of genes involved in extracellular matrix (ECM) organization; however, the genes varied between the cell types. At the protein level, myometrial spheroids had alterations in proteins associated with uterine fibroids (q=1.00x10^-33). There were alterations in collagen abundance in fibroid spheroids, but not collagen 1 although the collagenase MMP-1 was significantly lower in fibroid spheroids. Enrichment analysis identified ECM-receptor interactions as enriched in compression-induced changes between the cell types.

Conclusions: Compressive forces must be considered to study some of the important differences between fibroids and myometrium, including ephrin signaling. Enrichment analysis of the proteins with different abundances suggests that compression may also be involved in fibroid tumor initiation.