27-Hydroxycholesterol (25(R)-27-hydroxy Cholesterol) is a selective modulator of estrogen receptor and an agonist of the liver X receptor.

27-Hydroxycholesterol activates estrogen receptors, adversely impacting prostate cancer cell lines by significantly enhancing cell proliferation in LNCaP and PC3 cells. This proliferation can be mitigated by estrogen receptor inhibitors [1]. As an endogenous selective estrogen receptor modulator, 27-Hydroxycholesterol exhibits substantial partial agonist activity across various cellular models, notably increasing gene transcription and cell proliferation in breast cancer contexts [2]. Produced from cholesterol by the enzyme CYP27A1, it plays a vital role in regulating intracellular cholesterol equilibrium. Its pro-tumorigenic effects can be diminished by either statins or directly inhibiting CYP27A1 [3]. Furthermore, 27-Hydroxycholesterol's conversion from cholesterol is crucial for LXR activation when faced with cholesterol excess [4].