17β-Estradiol promotes the synthesis and the secretion of annexin I in the CCRF-CEM human cell line

Abstract

Aims: Annexin I (ANXA1), a 37 kDa member of the annexin family of Ca²⁺-binding and phospholipidbinding proteins, is particularly abundant in various populations of peripheral blood leukocytes. Since this protein modulates the anti-inflammatory actions of the steroid hormones, the purpose of this study was to investigate the effects of the female sex steroid hormone, 17β-estradiol (E₂β), on the synthesis and secretion of ANXA1 in the human CCRF-CEM acute lymphoblastic leukemia cell line.Methods: Complementary reverse transcription-polymerase chain reaction and Western blot assays were performed to study the effect of E₂β on the expression of mRNA and protein ANXA1, respectively.Results and discussion: Treatment of CCRF-CEM cells with E₂β, for 30 min, stimulated the synthesis of ANXA1 mRNA molecules, and increased the cellular level of ANXA1 protein. Moreover, when the cells were incubated with E₂β, under the same experimental conditions, a significant increase in the amount of ANXA1 secreted from the cells was also detected. ICI 182,780, a selective inhibitor of the intracellular estrogen receptor, had no effect on the E₂β-stimulated expression and externalisation of ANXA1. Taken together, these results indicate that E₂β induces de novo synthesis of ANXA1 and stimulates its secretion in the CCRF-CEM cell line, apparently through a mechanism independent of the intracellular estrogen receptor.