title: Apolipoprotein D (APOD) is a putative biomarker of androgen receptor function in androgen insensitivity syndrome.
abstract: Androgen insensitivity syndrome (AIS) is the most common cause of disorders of sex development usually caused by mutations in the androgen receptor (AR) gene. AIS is characterized by a poor genotype-phenotype correlation, and many patients with clinically presumed AIS do not seem to have mutations in the AR gene. We therefore aimed at identifying a biomarker enabling the assessment of the cellular function of the AR as a transcriptional activator. In the first step, we used complementary DNA (cDNA) microarrays for a genome-wide screen for androgen-regulated genes in two normal male primary scrotal skin fibroblast strains compared to two labia majora fibroblast strains from 46,XY females with complete AIS (CAIS). Apolipoprotein D (APOD) and two further transcripts were significantly upregulated by dihydrotestosterone (DHT) in scrotum fibroblasts, while CAIS labia majora cells were unresponsive. Microarray data were well correlated with quantitative real-time polymerase chain reaction (qRT-PCR; R = 0.93). Subsequently, we used qRT-PCR in independent new cell cultures and confirmed the significant DHT-dependent upregulation of APOD in five normal scrotum strains [13.5 +/- 8.2 (SD)-fold] compared with three CAIS strains (1.2 +/- 0.7-fold, p = 0.028; t test) and six partial androgen insensitivity syndrome strains (2 +/- 1.3-fold, p = 0.034; t test). Moreover, two different 17ss-hydroxysteroid dehydrogenase III deficiency labia majora strains showed APOD induction in the range of normal scrotum (9.96 +/- 1.4-fold), supporting AR specificity. Therefore, qRT-PCR of APOD messenger RNA transcription in primary cultures of labioscrotal skin fibroblasts is a promising tool for assessing AR function, potentially allowing a function-based diagnostic evaluation of AIS in the future.
authors.affiliation: Department of Pediatrics, University-Hospital Schleswig-Holstein, Christian Albrechts University of Kiel, Germany. appari@pediatrics.uni-kiel.de
authors.forename: Mahesh
authors.initials: M
authors.lastname: Appari
authors.forename: Ralf
authors.initials: R
authors.lastname: Werner
authors.forename: Lutz
authors.initials: L
authors.lastname: Wünsch
authors.forename: Gunnar
authors.initials: G
authors.lastname: Cario
authors.forename: Janos
authors.initials: J
authors.lastname: Demeter
authors.forename: Olaf
authors.initials: O
authors.lastname: Hiort
authors.forename: Felix
authors.initials: F
authors.lastname: Riepe
authors.forename: James D
authors.initials: JD
authors.lastname: Brooks
authors.forename: Paul-Martin
authors.initials: PM
authors.lastname: Holterhus