A 13-Steroid Serum Panel Based on LC-MS/MS: Use in Detection of Adrenocortical Carcinoma

BACKGROUND Adrenocortical carcinoma (ACC) is a rare malignancy, with an annual incidence of 1 or 2 cases per million. Biochemical diagnosis is challenging because up to two-thirds of the carcinomas are biochemically silent, resulting from de facto enzyme deficiencies in steroid hormone biosynthesis. Urine steroid profiling by GC-MS is an effective diagnostic test for ACC because of its capacity to detect and quantify the increased metabolites of steroid pathway synthetic intermediates. Corresponding serum assays for most steroid pathway intermediates are usually unavailable because of low demand or lack of immunoassay specificity. Serum steroid analysis by LC-MS/MS is increasingly replacing immunoassay, in particular for steroids most subject to cross-reaction. METHODS We developed an LC-MS/MS method for the measurement of serum androstenedione, corticosterone, cortisol, cortisone, 11-deoxycorticosterone, 11-deoxycortisol, 21-deoxycortisol, dehydroepiandrosterone sulfate, pregnenolone, 17-hydroxypregnenolone, progesterone, 17-hydroxyprogesterone, and testosterone. Assay value in discriminating ACC from other adrenal lesions (phaeochromocytoma/paraganglioma, cortisol-producing adenoma, and lesions demonstrating no hormonal excess) was then investigated. RESULTS In ACC cases, between 4 and 7 steroids were increased (median = 6), and in the non-ACC groups, up to 2 steroids were increased. 11-Deoxycortisol was markedly increased in all cases of ACC. All steroids except testosterone in males and corticosterone and cortisone in both sexes were of use in discriminating ACC from non-ACC adrenal lesions. CONCLUSIONS Serum steroid paneling by LC-MS/MS is useful for diagnosing ACC by combining the measurement of steroid hormones and their precursors in a single analysis.

Targeted Disruption of the kstD Gene Encoding a 3-Ketosteroid Δ1-Dehydrogenase Isoenzyme ofRhodococcus erythropolis Strain SQ1

ABSTRACT Microbial phytosterol degradation is accompanied by the formation of steroid pathway intermediates, which are potential precursors in the synthesis of bioactive steroids. Degradation of these steroid intermediates is initiated by Δ1-dehydrogenation of the steroid ring structure. Characterization of a 2.9-kb DNA fragment ofRhodococcus erythropolis SQ1 revealed an open reading frame (kstD) showing similarity with known 3-ketosteroid Δ1-dehydrogenase genes. Heterologous expression ofkstD yielded 3-ketosteroid Δ1-dehydrogenase (KSTD) activity under the control of the lac promoter inEscherichia coli. Targeted disruption of thekstD gene in R. erythropolis SQ1 was achieved, resulting in loss of more than 99% of the KSTD activity. However, growth on the steroid substrate 4-androstene-3,17-dione or 9α-hydroxy-4-androstene-3,17-dione was not abolished by thekstD gene disruption. Bioconversion of phytosterols was also not blocked at the level of Δ1-dehydrogenation in the kstD mutant strain, since no accumulation of steroid pathway intermediates was observed. Thus, inactivation ofkstD is not sufficient for inactivation of the Δ1-dehydrogenase activity. Native polyacrylamide gel electrophoresis of cell extracts stained for KSTD activity showed thatR. erythropolis SQ1 in fact harbors two activity bands, one of which is absent in the kstD mutant strain.