Differential Gene Expression in Fibroid Progenitor Cells: New Perspectives on Old Pathways

Presentation Number: SUN-0033
Date of Presentation: June 22nd, 2014

Molly Bennette Moravek*1, Ping Yin1, Masanori Ono1, Matthew T Dyson2 and Serdar Ekrem Bulun1
1Northwestern University, Chicago, IL, 2Northwestern University

Abstract

Recently, a small population of uterine fibroid cells with progenitor cell properties was found to be necessary for ovarian steroid-dependent growth of fibroids. Our lab discovered a novel way of isolating these progenitor cells using cell surface markers CD34 and CD49b, which avoids the pitfalls of the side population technique for isolating stem cells, and has revealed 3 populations of fibroid cells:  CD34+/CD49b+ (progenitor), CD34+/CD49- (intermediate), and CD34-/CD49b- (differentiated).  In order to determine differential gene expression between these cell populations and identify critical gene pathways that may explain the pathogenesis of uterine fibroids, fibroid tissue was collected from 8 premenopausal African American subjects at the time of surgery and cells sorted by flow cytometry based on CD34 and CD49b expression.  RNA was isolated and microarray performed using the Illumina Human HT-12 Expression BeadChip. Gene expression was analyzed using multiple t-tests, with differential expression defined as fold change >1.5 and false discovery rate <5%.  Functional pathway analysis using Kyoto Encyclopedia of Genes and Genomes indicated genes involved in inflammation, apoptosis, wound healing, TGF-β signaling, and extracellular matrix receptor interaction were highly differentially expressed in CD34+/CD49b+ cells. Gene expression profiling revealed that the three cell populations were molecularly distinct, with over 1000 genes differentially expressed between them. Genes involved in the TGF-β and IGF pathways, two pathways implicated in uterine fibroid pathogenesis, were differentially expressed between the different populations, validated by PCR.  TGF-β3 was upregulated in CD34+/CD49- cells, whereas TGF-β1 was upregulated in CD34-/CD49- cells.  Interestingly, the TGF-β receptors were upregulated in the CD34+/CD49+ cells.  Similarly, IGF-I and –II were upregulated in CD34+/CD49- cells, but most of the IGF binding proteins were upregulated in CD34+/CD49+ cells.  Additionally, estrogen and progesterone receptor (ER and PR) genes were downregulated in CD34+/CD49b+ cells. These results suggest that the CD34+/CD49b+ fibroid progenitor cells have a molecular signature unique from CD34+/CD49- and CD34-/CD49b- cells.  Interestingly, ligands, receptors, and binding proteins from the TGF-β and IGF signaling pathways showed differential expression in different cell types.  This information, combined with the lack of ER and PR, suggests paracrine interaction between the cell populations necessary for hormone-dependent fibroid growth. Further evaluation of these interactions may lead to the development of new treatment options. Treatments targeting fibroid progenitor cells and interactions with surrounding cells could not only treat current fibroids, but also prevent the growth of new tumors.

 

Nothing to Disclose: MBM, PY, MO, MTD, SEB