title: Abundance of DLK1, differential expression of CYP11B1, CYP21A2 and MC2R, and lack of INSL3 distinguish testicular adrenal rest tumours from Leydig cell tumours.
abstract: OBJECTIVE
  Testicular adrenal rest tumours (TARTs) are a common finding in patients with congenital adrenal hyperplasia (CAH). These tumours constitute a diagnostic and management conundrum and may lead to infertility. TART cells share many functional and morphological similarities with Leydig cells (LCs), and masses consisting of such cells are occasionally misclassified as malignant testicular tumours, which may lead to erroneous orchiectomy in these patients.
  
  
  METHODS
  In this study, we aimed to investigate the potential of LC developmental markers and adrenal steroidogenic markers in the differential diagnosis of TARTs and malignant LC tumours (LCTs).
  
  
  METHODS
  We investigated mRNA and protein expression of testicular steroidogenic enzymes; CYP11A1 and HSD3B1/2, markers of adrenal steroidogenesis; CYP11B1, CYP21A2 and ACTH receptor/melanocortin 2 receptor (MC2R), and markers of LC maturation; and delta-like 1 homolog (DLK1) and insulin-like 3 (INSL3) in testicular biopsies with TART, orchiectomy specimens with LCTs and samples from human fetal adrenals.
  
  
  RESULTS
  Expression of testicular steroidogenic enzymes was observed in all specimens. All investigated adrenal steroidogenic markers were expressed in TART, and weak reactions for CYP11B1 and MC2R were observed at the protein level in LTCs. TART and fetal adrenals had identical expression profiles. DLK1 was highly expressed and INSL3 not detectable in TART, whereas INSL3 was highly expressed in LCTs.
  
  
  CONCLUSIONS
  The similar expression profiles in TART and fetal adrenals as well as the presence of classical markers of adrenal steroidogenesis lend support to the hypothesis that TART develops from a displaced adrenal cell type. Malignant LCTs seem to have lost DLK1 expression and do not resemble immature LCs. The different expression pattern of DLK1, INSL3 and most adrenocortical markers adds to the elucidation of the histogenesis of testicular interstitial tumours and may facilitate histopathological diagnosis.
authors.affiliation: Department of Growth and Reproductionand International Center for Research and Research Training in Endocrine Disrupting Effects on Male Reproduction & Child Health (EDMaRC), Copenhagen University Hospital, Section 5064, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen Ø, Denmark gretelottrup@gmail.com Ewa.Rajpert-De.Meyts@regionh.dk.
authors.forename: Grete
authors.initials: G
authors.lastname: Lottrup
authors.affiliation: Department of Growth and Reproductionand International Center for Research and Research Training in Endocrine Disrupting Effects on Male Reproduction & Child Health (EDMaRC), Copenhagen University Hospital, Section 5064, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen Ø, Denmark.
authors.forename: John E
authors.initials: JE
authors.lastname: Nielsen
authors.affiliation: Department of Growth and Reproductionand International Center for Research and Research Training in Endocrine Disrupting Effects on Male Reproduction & Child Health (EDMaRC), Copenhagen University Hospital, Section 5064, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen Ø, Denmark.
authors.forename: Niels E
authors.initials: NE
authors.lastname: Skakkebæk
authors.affiliation: Department of Growth and Reproductionand International Center for Research and Research Training in Endocrine Disrupting Effects on Male Reproduction & Child Health (EDMaRC), Copenhagen University Hospital, Section 5064, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen Ø, Denmark.
authors.forename: Anders
authors.initials: A
authors.lastname: Juul
authors.affiliation: Department of Growth and Reproductionand International Center for Research and Research Training in Endocrine Disrupting Effects on Male Reproduction & Child Health (EDMaRC), Copenhagen University Hospital, Section 5064, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen Ø, Denmark gretelottrup@gmail.com Ewa.Rajpert-De.Meyts@regionh.dk.
authors.forename: Ewa
authors.initials: E
authors.lastname: Rajpert-De Meyts
mesh_terms: D000314:Adrenal Rest Tumor / Q000175:diagnosis* / Q000235:genetics* / Q000378:metabolism; D000328:Adult; D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism; D002135:Calcium-Binding Proteins; D003937:Diagnosis, Differential; D005260:Female; D005333:Fetus / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007328:Insulin / Q000235:genetics / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D007984:Leydig Cell Tumor / Q000175:diagnosis* / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D044103:Receptor, Melanocortin, Type 2 / Q000235:genetics / Q000378:metabolism; D013252:Steroid 11-beta-Hydroxylase / Q000235:genetics / Q000378:metabolism; D013255:Steroid 21-Hydroxylase / Q000235:genetics / Q000378:metabolism; D013736:Testicular Neoplasms / Q000175:diagnosis* / Q000235:genetics* / Q000378:metabolism; D059467:Transcriptome
chemical_list: D014408:Biomarkers, Tumor; D002135:Calcium-Binding Proteins; C512941:DLK1 protein, human; D007328:Insulin; D036341:Intercellular Signaling Peptides and Proteins; C084797:Leydig insulin-like protein; D008565:Membrane Proteins; D011506:Proteins; D044103:Receptor, Melanocortin, Type 2; C531510:CYP21A2 protein, human; D013255:Steroid 21-Hydroxylase; D013252:Steroid 11-beta-Hydroxylase