The expression of estrogen receptor isoforms alpha, beta and insulin-like growth factor-I in uterine leiomyoma.

BACKGROUND

A prospective study focusing on leiomyoma was conducted to investigate the expression of estrogen receptor-alpha (ER alpha), estrogen receptor-beta (ER beta) and insulin-like growth factor-I (IGF-I) to elucidate their roles in the pathogenesis of leiomyoma.

METHODS

Twenty-one leiomyomal and six paired myometrial tissues were included in the study. The levels of ER alpha, ER beta and IGF-I mRNAs in leiomyoma and adjacent myometrium were analyzed by quantitative reverse transcription-polymerase chain reaction.

RESULTS

All tissues showed a higher ER alpha expression level. The correlation between ER alpha mRNA and IGF-I mRNA levels was significantly positive (r = 0.527, p = 0.014). The correlation between ER beta mRNA and IGF-I mRNA levels was also positive, but not statistically significant. In six paired leiomyoma and myometrium samples, the levels of ER alpha and ER beta mRNA exhibited no difference, and IGF-I mRNA levels were elevated in leiomyoma compared with paired myometrium (p < 0.05).

CONCLUSIONS

The expression of IGF-I mRNA increases in leiomyoma and ER alpha mRNA is positively correlated with IGF-I mRNA, which implies that estrogen upregulates the gene encoding IGF-I through ER alpha in leiomyoma; ER beta may also be involved in the IGF-I signaling pathway in leiomyoma.