Impact of progesterone on cytokine-stimulated nuclear factor-kappaB signaling in HeLa cells

Abstract

Objective. A key event in the pathways leading to preterm labor may be the activation of nuclear factor-kappaB (NF-κB) in the fetal membranes and the cervix. Anti-inflammatory agents, such as the corticosteroids, inhibit the activation of NF-κB. We proposed to investigate the effects of progesterone pretreatment on cytokine-stimulated activation of NF-κB in HeLa cells, a human cervical epithelial cell line.

Methods. HeLa cells were pretreated with 10⁻⁷ M progesterone for 24 hours and exposed to 1 ng/mL interleukin-1β (IL-1β) for 1 hour. Nuclear and cytosolic extracts were subjected to Western blot analysis using anti-p65 and anti-inhibitory protein-κBα (anti-IκBα) antibodies. Densitometric data (n = 5) were compared using Kruskal–Wallis test.

Results. Pretreatment with progesterone interfered with IL-1β-induced IκBα degradation. However, progesterone pretreatment resulted in a significant decrease in NF-κB protein subunit p65 in the cytoplasm. Pretreatment with progesterone did not reduce the amount of nuclear p65 and did not interfere with nuclear translocation of p65.

Conclusion. Our observations suggest that any possible role played by progesterone in preterm labor prevention is not exerted through anti-inflammatory mechanisms of NF-κB down-regulation.

Keywords:

• Progesterone
• nuclear factor-kappaB
• preterm delivery
• inflammation