Common fibroid-associated genes are differentially expressed in phenotypically dissimilar cell populations isolated from within human fibroids and myometrium.

Uterine fibroids are a prevalent gynaecological condition in reproductive-aged women and are the commonest reason for hysterectomy. The cellular composition of clonal fibroids are heterogeneous, with phenotypically dissimilar cells that include smooth muscle cells (SMC), vascular SMC (VSMC) and fibroblasts. The aim of our study was to investigate genes that are commonly differentially expressed between fibroid and myometrial whole tissues in phenotypically different sub-populations of cells isolated from fibroid and myometrium. Genes to be investigated by fluorescence-activated cell sorting, quantitative real-time PCR and immunocytochemistry include transforming growth factor β (TGFB) and retinoic acid (RA) signalling families and steroid hormone receptors. We hypothesised that each cell population isolated from fibroid and myometrium would differ in the expression of fibroid-associated genes. We demonstrated that phenotypically different cellular constituents of uterine fibroids differentially express cellular RA-binding protein 2 (CRABP2), progesterone receptor B (PRB) and TGFB receptor 2 mRNA in fibroid-derived cells of VSMC and SMC phenotype. CRABP2 mRNA was also differentially expressed in fibroblasts and VSMC sub-populations from within clonal fibroid tumours. We conclude that differential regulation of RA, TGFB and PR pathway transcription occurs in fibroid-associated SMC and -fibroblasts and that investigation of paracrine interactions between different cell types within the fibroid microenvironment provides an important new paradigm for understanding the pathophysiology of this common disease.