Altered expression of activin, cripto, and follistatin in the endometrium of women with endometrioma

OBJECTIVE: To evaluate the expression pattern of activin A, activin receptors, and activin modulators messenger RNA (mRNA) in the eutopic endometrium of patients with endometriosis at different phases of the menstrual cycle and to evaluate the mRNA expression of the same proteins in endometriomas during the menstrual cycle. DESIGN: Prospective study. SETTING: University hospital. PATIENT(S): Women with and without endometriosis. INTERVENTION(S): Samples of endometrial and endometriotic tissue from women with endometrioma (n=48), and endometrial samples from women without endometriosis (controls) (n=48). MAIN OUTCOME MEASURE(S): Quantification of activin A, activin B, activin receptor II, nodal, cripto, inhibin α, and follistatin expression by real-time reverse-transcriptase polymerase chain reaction (RT-PCR). RESULT(S): The eutopic endometrium of patients with endometriosis showed [1] higher activin A mRNA expression in the proliferative phase and a lack of late secretory phase peak, [2] a lack of endometrial cycle-related variations of cripto and inhibin α mRNA expression, and [3] an inverse expression pattern of follistatin mRNA. Endometriomas showed similar variations in the expression of activin-related protein mRNA during the menstrual cycle as eutopic endometrium. CONCLUSION(S): The disturbed expression of endometrial activin A, cripto (activin receptor antagonist), and follistatin (activin-binding protein) suggests a dysfunction of the activin pathway in endometriosis. Endometriomas showed similar changes of activin-related proteins during the menstrual cycle, which supports a common biology for eutopic and ectopic endometrium in endometriosis.