Increased expression of aromatase cytochrome P450 enzyme is associated with prolactinoma invasiveness in post-menopausal women

Objectives To investigate the expression levels of aromatase cytochrome P450 enzyme (P450AROM) and related molecules-estrogen receptor-beta (ER-beta), Ki-67, and p53-in prolactinoma tumor tissue from pre- and post-menopausal women, and to determine the associations of tumor invasiveness with expression levels of these genes. Methods This study recruited 90 patients with prolactinoma who underwent adenoidectomy between 2012 and 2017. Information was collected regarding clinical characteristics, hormones, laboratory tests, and magnetic resonance imaging-assessed tumor invasiveness. Expression levels of P450AROM, ER-beta, Ki-67, and p53 were examined by immunohistochemistry in prolactinoma tissues. Results Increased P450AROM expression was found in invasive prolactinoma tissues in post-menopausal women, compared with its expression in non-invasive prolactinoma tissues. ER-beta level was significantly higher in patients resistant to treatment with bromocriptine, a dopamine agonist. However, there were no differences in rate of resistance to treatment (8.2% vs. 3.4%) or expression levels of P450AROM, Ki-67, p53, and ER-beta between pre- and post-menopausal patients. Conclusions Our results demonstrated that increased P450AROM expression in prolactinoma of post-menopausal women was positively associated with invasiveness. Moreover, ER-beta level was higher in both pre- and post-menopausal patients who were resistant to dopamine agonist treatment.