The Expression of Estrogen Receptor Subtypes in Prolactinomas and Their Relationship to Tumor Biological Behavior

Dopamine agonists (DA) are a first-line therapy for prolactinomas (PA). However, nearly 10% of prolactinomas do not respond to DA therapy. A considerable number of studies have shown that estrogen plays an important role in the development of prolactinomas. However, the expression of estrogen receptors (ER) in prolactinomas has not been fully explored. Accordingly, we examined the levels of ESR1 and its subtypes Delta 5-Del-ESR1 and ESR2 mRNA in prolactinomas. In the present study, we found that ESR1 mRNA levels were significantly lower in women of childbearing age group compared to men (P<0.01) and post-menopausal women (P<0.05). In addition, ESR1 mRNA levels showed a significant positive correlation with the levels of prolactin (PRL). Moreover, ESR1 mRNA levels were significantly lower in noninvasive prolactinomas compared to invasive prolactinomas.