BACKGROUND. A high throughput, high pressure liquid chromatographic (HPLC) method with triple quadrupole mass spectral detection (LC/MS/MS) was validated for the measurement of 5 endogenous androgens in human plasma and serum and applied to various in vivo and in vitro study samples to pursue a better understanding of the interrelationship of the androgen axis, intracrine metabolism, and castration-recurrent prostate cancer (CaP).
Methods: A Shimadzu HPLC system interfaced with a Sciex QTRAP 5500 mass spectrometer with electrospray ionization was used with in line column-switching. Samples were liquid/liquid extracted and chromatographed on a Luna C18(2) column at 60°C with a biphasic gradient using a 15-min run time.
Results: The method was validated for five androgens in human plasma and serum, and applied to four sets of samples. Plasma (n=188) and bone marrow aspirate (n=129) samples from patients with CaP, who received abiraterone acetate plus prednisone for up to 945 days(135 weeks), had undetectable androgens after 8 weeks of treatment. Plasma dehydroepiandrosterone(DHEA) concentrations were higher in African Americans than Caucasian Americans with newly diagnosed CaP. Analysis of prostate tumor tissue homogenates demonstrated reproducible testosterone (T) and dihydrotestosterone (DHT) concentrations with a minimal sample size of 1.0–2.0 mg of tissue. Finally, cell pellet and media samples from the LNCaP C4-2 cell line showed conversion of T to DHT.
Conclusion: The proposed LC/MS/MS method was validated for quantitation of five endogenous androgens in human plasma and serum, and effectively profiles androgens in clinical specimens and cell culture samples.