Identification of novel androgen receptor target genes in prostate cancer
MOLECULAR CANCER
Authors: Jariwala, Unnati; Prescott, Jennifer; Jia, Li; Barski, Artem; Pregizer, Steve; Cogan, Jon P.; Arasheben, Armin; Tilley, Wayne D.; Scher, Howard I.; Gerald, William L.; Buchanan, Grant; Coetzee, Gerhard A.; Frenkel, Baruch
Abstract
Background: The androgen receptor (AR) plays critical roles in both androgen-dependent and castrate-resistant prostate cancer (PCa). However, little is known about AR target genes that mediate the receptor's roles in disease progression. Results: Using Chromatin Immunoprecipitation (ChIP) Display, we discovered 19 novel loci occupied by the AR in castrate resistant C4-2B PCa cells. Only four of the 19 AR-occupied regions were within 10-kb 5'-flanking regulatory sequences. Three were located up to 4-kb 3' of the nearest gene, eight were intragenic and four were in gene deserts. Whereas the AR occupied the same loci in C4-2B (castrate resistant) and LNCaP (androgen-dependent) PCa cells, differences between the two cell lines were observed in the response of nearby genes to androgens. Among the genes strongly stimulated by DHT in C4-2B cells-D-dopachrome tautomerase (DDT), Protein kinase C delta (PRKCD), Glutathione S-transferase theta 2 (GSTT2), Transient receptor potential cation channel subfamily V member 3 (TRPV3), and Pyrroline-5-carboxylate reductase 1 (PYCR1)-most were less strongly or hardly stimulated in LNCaP cells. Another AR target gene, ornithine aminotransferase (OAT), was AR-stimulated in a ligand-independent manner, since it was repressed by AR siRNA knockdown, but not stimulated by DHT. We also present evidence for in vivo AR-mediated regulation of several genes identified by ChIP Display. For example, PRKCD and PYCR1, which may contribute to PCa cell growth and survival, are expressed in PCa biopsies from primary tumors before and after ablation and in metastatic lesions in a manner consistent with AR-mediated stimulation. Conclusion: AR genomic occupancy is similar between LNCaP and C4-2B cells and is not biased towards 5' gene flanking sequences. The AR transcriptionally regulates less than half the genes nearby AR-occupied regions, usually but not always, in a ligand-dependent manner. Most are stimulated and a few are repressed. In general, response is stronger in C4-2B compared to LNCaP cells. Some of the genes near AR-occupied regions appear to be regulated by the AR in vivo as evidenced by their expression levels in prostate cancer tumors of various stages. Several AR target genes discovered in the present study, for example PRKCD and PYCRI, may open avenues in PCa research and aid the development of new approaches for disease management.
Genotype phenotype spectrum of PYCR1-related autosomal recessive cutis laxa
MOLECULAR GENETICS AND METABOLISM
Authors: Dimopoulou, Aikaterini; Fischer, Bjorn; Gardeitchik, Thatjana; Schroeter, Phillipe; Kayserili, Hullya; Schlack, Claire; Li, Yun; Brum, Jaime Moritz; Barisic, Ingeborg; Castori, Marco; Spaich, Christiane; Fletcher, Elaine; Mahayri, Zeina; Bhat, Meenakshi; Girisha, Katta M.; Lachlan, Katherine; Johnson, Diana; Phadke, Shubha; Gupta, Neerja; Simandlova, Martina; Kabra, Madhulika; David, Albert; Nijtmans, Leo; Chitayat, David; Tuysuz, Beyhan; Brancati, Francesco; Mundlos, Stefan; Van Maldergem, Lionel; Morava, Eva; Wollnik, Bernd; Kornak, Uwe
Abstract
Autosomal recessive cutis laxa type 2B (ARCL2B; OMIM # 612940) is a segmental progeroid disorder caused by mutations in PYCR1 encoding pyrroline-5-carboxylate reductase 1, which is part of the conserved proline de novo synthesis pathway. Here we describe 33 patients with PYCR1-related ARCL from 27 families with initial diagnoses varying between wrinkly skin syndrome, gerodermia osteodysplastica, De Barsy syndrome or more severe progeria syndromes. Given the difficult differential diagnosis of ARCL syndromes we performed a systematic comparison of clinical features of PYCR1-related ARCL. Intrauterine growth retardation, a characteristic triangular facial gestalt, psychomotor retardation, and hypotonia were the most relevant distinctive hallmarks of ARCL due to proline de novo synthesis defects. Corneal clouding or cataracts, athetoid movements, and finger contractures were rather rare features, but had a high predictive value. In our cohort we identified 20 different PYCR1 mutations of which seven were novel. Most of the mutations accumulated in exons 4 to 6. Missense alterations of highly conserved residues were most frequent followed by splice site changes and a single nonsense mutation. Analysis of genotype phenotype correlation revealed that patients with mutations in the first two exons had lower average clinical scores and absent or only mild intellectual disability. Structural analyses predicted interference with PYCR1 multimerization for a subset of missense mutations. These findings have implications for the clinics as well as the pathomechanism of PYCR1-related ARCL. (C) 2013 Elsevier Inc. All rights reserved.