Hyperplastic ovarian stromal cells express genes associated to tumor progression: a case study

Abstract

The current study presents the analysis of stromal cells obtained from an hyperplastic left-ovary of a Holstein cow. Cultured hyperplastic stromal cells displayed a fibroblast-like morphology and ceased proliferation after the 8th passage. The non-cancerous nature of stromal cells was confirmed by in vitro cell proliferation and migration assays. Negligible amounts of E2 were detected in the spent media of cultured stromal cells, which suggests that stromal cells were non-estradiol synthesizing cells. As revealed in immunofluorescence and gene expression analysis, the hyperplastic stromal cells explicitly expressed vimentin in their cytoskeleton. Upon hematoxylin staining, a highly dense population of stromal cells was observed in the stromal tissue of the hyperplastic ovary. To explore genome-wide alterations, mRNA microarray analysis was performed using Affymetrix Bovine Gene 1.0ST Arrays compared to normal ovarian derived stromal cells. The microarray identified 1396 differentially expressed genes, of which 733 were up- and 663 down-regulated in hyperplastic stromal cells. Importantly, asporin (ASPN) and vascular cell adhesion molecule 1 (VCAM1) were among the highly up-regulated genes. Higher expression of ASPN was also confirmed by immunohistochemistry and RT-qPCR analysis. Ingenuity pathway analysis (IPA) identified about 98 significantly enriched (-log (p value ≥ 1.3) canonical pathways, importantly of which the “Sirutin Signaling Pathway” and “Mitochondrial Dysfunction” were highly activated while “Oxidative phosphorylation” was inhibited. Additionally, higher proportion of hyperplastic stromal cells in the S-phase of cell cycle, could be attributed to higher expression levels of cell proliferation genes such as CCND2 and CDK6.