Immediately before parturition the cervix undergoes striking changes in structure (ripening) that facilitate dilatation and effacement. Cervical ripening shares many features in common with inflammation-associated tissue remodeling, making it a valuable process to explore with respect to the biochemical events in extracellular matrix restructuring. Cervical ripening can be pharmacologically induced with prostaglandin E2 (PGE2). Among the biochemical changes in the cervix at parturition is a marked increase in the hyaluronic acid (HA) content. HA and HA-binding proteins have been implicated in tissue hydration, release of collagenase, and leukocyte migration, but their roles in cervical ripening have not been explored. In the present study we examined the ability of PGE2 to induce expression of the HA-binding protein, tumor necrosis factor-stimulated gene (TSG)-6, in human cervical smooth muscle cells (hCSMCs) and compared the PGE2 response to that of tumor necrosis factor-α (TNF-α), an established inducer of TSG-6. TNF-α stimulated TSG-6 mRNA accumulation in a dose- and time-dependent manner, with the maximal response observed at 10 ng/ml after 6 hours of incubation. PGE2 stimulated TSG-6 mRNA expression, but the magnitude of response was substantially less than that produced by TNF-α, and it was maximal only after 24 hours of incubation. Quantitative real-time polymerase chain reaction was performed to assess the induction of TSG-6 mRNA and nascent transcripts at 24 hours of treatment. Induction of TSG-6 mRNA and nascent transcripts in response to 10 μmol/L of PGE2 was 5.7-fold and 6.3-fold greater than control values, respectively, whereas TNF-α (10 ng/ml) induced TSG-6 mRNA and nascent transcripts by 80-fold and 134-fold, respectively. TNF-α and PGE2 stimulated secretion of TSG-6 into the culture medium as detected by Western blotting. The effects of PGE2 on secretion of TSG-6 were delayed compared to TNF-α. A 1.3-kb fragment of the human TSG-6 proximal promoter drove luciferase expression in transfected hCSMCs. PGE2 increased TSG-6 promoter activity 1.75-fold. Paradoxically, TNF-α reduced TSG-6 promoter activity by 50%. We conclude that hCSMCs express the hyaladherin TSG-6; that TSG-6 expression in these cells is regulated by PGE2 as well as proinflammatory cytokines; responses of hCSMCs to TNF-α and PGE2 are distinct in terms of magnitude and the time course; and PGE2 and TNF-α exert different effects on the TSG-6 proximal promoter.
ASJC Scopus subject areas
- Pathology and Forensic Medicine