Administration of βHCG leads to dose-dependent changes of gene expression signature of endometriotic stromal cells

Preliminary studies have shown that systemic β-human chorionic gonadotrophin (βHCG) therapy alleviates endometriosis-related chronic pelvic pain. The underlying mechanism, however, is completely unknown. This study has investigated the dose-dependent alterations in the overall gene expression profile of endometriosis-derived stromal cells under increasing concentrations of βHCG by using the Affymetrix GeneChip U133 Set. It has been previously shown that βHCG concentrations of 0.1 U/ml and higher lead to a significant and dose-dependent increase in the expression of 68 genes. This study reports on a cluster analysis which identified three clusters of genes with a comparable expression pattern in response to increasing concentrations of βHCG. Most of the up-regulated genes encoded proteins that are involved in cell adhesion, intercellular communication, extracellular matrix remodelling, apoptosis and inflammation. Stromal monocultures from eight patients, treated with and without 50 U/ml of βHCG, were then incubated and real-time polymerase chain reaction for the highly up-regulated genes PAI2, DUSP6, PLAU and MMP1 performed in order to validate the cDNA array findings in patients with endometriosis. Taken together, this study shows that βHCG induces dose-dependent characteristic response clusters in the gene expression profile of stromal cells obtained from endometriotic lesions which could explain the differential biological responses of βHCG in endometriosis.