Endocrine Abstracts

Objectives: Vascular endothelial growth factor (VEGF) and its soluble receptor (sVEGFR-1) are key regulators in human ovarian angiogenesis. VEGF promotes blood vessel growth while sVEGFR-1 is a VEGF antagonist. A promising candidate in sVEGFR-1 regulation is TIMP-1 (tissue inhibitor of metalloproteinases 1), which is involved in extracellular matrix remodelling. The aim of our research is to determine if TIMP-1 influences sVEGFR-1 secretion in endothelial cells.

Methods: Pooled human endothelial cells were seeded in 24-multiwell plates. Twenty-four hours afterwards, TIMP-1 was downregulated in the cells by RNA interference using four TIMP-1 siRNAs (small interfering RNAs) and two unspecific siRNAs. After four days incubation, TIMP-1 and sVEGFR-1 concentrations were quantified in culture supernatant by enzyme-linked immunosorbent assay (ELISA). Control endothelial cells were used without additional treatment.

Results: As shown in ELISA assays, TIMP-1 concentration in the endothelial culture supernatant was significantly reduced between 65% and 78% by using the four TIMP-1 siRNAs when compared to untreated control cells. According to this, sVEGFR-1 concentration was also significantly decreased between 39% and 69% in the cell culture supernatant by using the specific siRNAs. Endothelial cells transfected with the unspecific siRNAs, however, showed similar TIMP-1 and sVEGFR-1 amounts like untreated controls.

Conclusion: The amount of soluble VEGF receptor 1 was significantly reduced in the TIMP-1 knockdown experiment. Therefore, sVEGFR-1 secretion in endothelial cells can be regulated by TIMP-1.