부산대학교 도서관

Increased mammographic density (MD) is a strong and independent risk factor for breast cancer. Lifetime oestrogenic exposure is associated with increased MD, however androgenic effects on MD have not been widely investigated. We studied the effect of 17β-oestradiol (E2) alone or in combination with an androgen receptor (AR) agonist (5α-dihydrotestosterone [DHT]) or a selective AR modulator (Enobosarm), in modulating MD as measured via single-sided Portable NMR in a patient-derived explant (PDE) model of normal human mammary tissue. We observed an upward trend in explants treated with E2 alone in 3/6 cases, an effect which appeared to be somewhat influenced by menopausal status. Co-treatment of E2 with the AR agonists DHT or Enobosarm however effected a downward trend in regards to MD. E2 significantly upregulated the ER regulated genes (ERGs) CELSR2and AR, and the AR regulated genes SEC14L2and GRPC5A, whereas E2 in combination with AR agonist Enobosarm downregulated ERGs SERPINA3, ATP6V1B1, TFF1and PR regulated gene RANK. Only GREB1and CLIC6were upregulated by E2 anddownregulated by the combination of E2 with Enobosarm. DHT + E2 exhibited no significant difference in expression of ER, AR or PR genes examined, compared with the effect of E2 alone. A negative trend was observed between ER protein levels and MD increase in PDEs. Since ER protein gets degraded upon hormone activation, this observation supports active ER signalling in the promotion of MD. Collectively, these findings supports the utility of single-sided Portable NMR for the measurement of MD in explanted human mammary tissue to detect MD change in response to exogenous hormone treatments. A mechanism through which activation of AR may reduce MD as a potential mechanism for reducing breast cancer risk associated to high MD is discussed.