Fig. 1: De novo androgen biosynthesis through 3βHSD1 is independent of CYP17A1.

A Steroid biosynthesis and canonical requirement for the CYP17A1 enzyme to synthesize 19-carbon androgens. B Intracellular testosterone and DHT levels in charcoal-stripped serum-starved or serum-free starved C4-2 prostate cancer cells cultured for 5 days. From n = 3 biological intra-assay replicate samples. C Intracellular androgen levels in parental and HSD3B1 knockout (KO) C4-2 cells. Also shown are the metabolic consequences of blocking HSD3B1 (encoding 3βHSD1) on the steroid A/B ring for testosterone and DHT biosynthesis. From n = 3 biological intra-assay replicate samples. N.D. not detectable. D Chromatography of ¹³C₃-testosterone and the levels of intracellular ¹³C₃-testosterone in ethanol- or 15 µM ¹³C₃-cholesterol -treated wild-type or HSD3B1 KO C4-2 cells. Cell pellets were collected after 5 days. ¹³C₃-Testosterone was measured by LC-MS/MS. From n = 3 biological intra-assay replicate samples except n = 4 for control treated with ¹³C₃-cholesterol samples. The chromatogram displays detection of ¹³C₃-testosterone. E Intracellular androgens in C4-2 cells treated with ethanol (EtOH) or the CYP17A1 inhibitors, TAK700 or ASN001. From n = 3 biological intra-assay replicate samples. All steroid measurements were performed using LC-MS/MS and are presented as mean +/− SD. Source data are provided as a Source Data file.