Dual actions of progesterone on uterine leiomyoma correlate with the ratio of progesterone receptor A:B

Abstract

Background. It has been suggested that progesterone down-regulated the levels of insulin-like growth factor-I (IGF-I). The present study was conducted to elucidate whether progesterone affects IGF-I mRNA through progesterone receptor B(PRB) mRNA in leiomyoma.Methods. Semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) was used to measure the level of progesterone receptor A (PRA), PRB, and IGF-I mRNA in 21 patients with uterine leiomyoma, and six pairs of matching leiomyomas and adjacent myometria were obtained in the secretory phase.Result. The ratios of PRA/PRB mRNA were positively correlated with the IGF-I mRNA levels in leiomyoma from women in the secretory phase (r = 0.732, p = 0.002 < 0.01), whereas the correlation between the level of PRB and IGF-I mRNA in leiomyomas was negative (r = −0.573, p = 0.025 < 0.05). The levels of PRA, PRB, and IGF-I mRNA were significantly higher in leiomyomas than in adjacent myometria.Conclusion. The progesterone may down-regulate IGF-I expression through PRB, and PRA appears to inhibit this function of progesterone by inhibiting the transcription of PRB; thus, the action of progesterone on leiomyoma growth may depend on different ratios of PRA and PRB.