5α-Pregnane-3β,6α-diol-20-one is a mitogenic metabolite of progesterone, and it can be produced in starved androgen-responsive prostate cancer cells.
Progesterone is converted to 5α-pregnane-3β,6α-diol-20-one in human fibroblasts[1]. Pregnenolone and progesterone are avidly metabolized to 5α-pregnan-3β,6α-diol-20-one in the C4.2 cell line, with nearly complete conversions at 24 h and 18 h, respectively. Preferential 5α-pregnan-3β,6α-diol-20-one formation from early steroid precursors is independent of CYP17A1 but rather relies on 3β-HSD activity[2].
[1]. Zhang J, et al. Progesterone metabolism in human fibroblasts is independent of P-glycoprotein levels and Niemann-Pick type C disease. J Steroid Biochem Mol Biol. 1999 Sep-Oct;70(4-6):123-31. [2]. de Mello Martins AGG, et al. CYP17A1-independent production of the neurosteroid-derived 5α-pregnan-3β,6α-diol-20-one in androgen-responsive prostate cancer cell lines under serum starvation and inhibition by Abiraterone. J Steroid Biochem Mol Biol. 2017 Nov;174:183-191.