Abnormal gene expression in uterine leiomyomas.

Uterine leiomyomas, benign tumors of myometrial origin, are the most common neoplasms of the uterus and occur in 20-30% of women over 30 years of age. Despite their high prevalence, little is known about the pathophysiology of these tumors. Recently, several studies have compared leiomyoma gene expression with that of normal myometrium. In general, the major differences in leiomyoma and myometrial gene expression are found for estrogen-regulated genes, which have elevated expression in myometrium during pregnancy. The tumors appear to maintain high sensitivity to estrogen during the estrogen-dominated follicular phase of the menstrual cycle, unlike normal myometrium. The abnormal gene expression of leiomyomas suggests that they are tumors of dysregulated differentiation and resemble the myometrium of pregnancy in several aspects.