Research article
Genomic expression and single-nucleotide polymorphism profiling discriminates chromophobe renal cell carcinoma and oncocytoma
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* Corresponding authors: Min-Han Tan tan.min.han@nccs.com.sg - Bin T Teh bin.teh@vai.org
1 Laboratory of Cancer Genetics, Van Andel Research Institute, 333 Bostwick Avenue NE, Grand Rapids, MI, 49503, USA
2 NCCS-VARI Translational Cancer Research Laboratory, National Cancer Centre Singapore, 11 Hospital Drive, 169610 Singapore
3 Department of Medical Oncology, National Cancer Centre Singapore, 11 Hospital Drive, 169610 Singapore
4 Department of Epidemiology and Public Health, National University of Singapore, 16 Medical Drive, 117597 Singapore
5 Department of Pathology, Singapore General Hospital, Outram Road, 169608 Singapore
6 Northwestern University Feinberg School of Medicine, 251 E. Huron, Chicago, IL, 60611, USA
7 Department of Urology, Iwate Medical University School of Medicine, 19-1, Uchimaru, Marioka, 020-8505 Japan
8 Laboratory of Computational Biology, Van Andel Research Institute, 333 Bostwick Avenue NE, Grand Rapids, MI, 49503, USA
9 Laboratory of Molecular Epidemiology, Van Andel Research Institute, 333 Bostwick Avenue NE, Grand Rapids, MI, 49503, USA
10 Laboratoire de Génétique, Hôpital Herriot, Batiment 7, Place d'Arsonval, 69437 Lyon Cedex 03, France
11 Laboratoire d’Anatomie Pathologique, Hôpital de Bicêtre, AP-HP, 78 rue du Général Leclerc, 94275 Le Kremlin-Bicêtre Cedex, France
12 Department of Biology and Pathology, Institut de Cancérologie Gustave Roussy, 39 rue Camile Desmoulins, 94805 Villejuif, France
13 Department of Urology, Hôpital Cochin, 27 rue du Faubourg Saint-Jacques, 75679 Paris Cedex 14, France
14 Service d'Urologie, Hôpital Necker, AP-HP, 149, rue de Sevres, 75743 Paris, France
15 Service d’Urologie, Hôpital de Bicêtre, AP-HP, 78 rue du Général Leclerc, 94275 Le Kremlin-Bicêtre, France
16 Service d'Anatomie Pathologique, Hôpital Saint Joseph, 185 rue Raymond Losserand, 75674 Paris Cedex, France
17 Laboratoire d'Anatomie Pathologique, Hôpital Cochin, 27 rue du Faubourg Saint-Jacques, 75679 Paris Cedex 14, France
18 Consultation d'Oncogénétique Spécialisée, Service d'Urologie, Hôpital de Bicêtre, 78 rue du General Leclerc, 94275 Le Kremlin-Bicêtre, France
19 Génétique Oncologique EPHE-INSERM U753 and Faculté de Médecine Paris-Sud, Le Kremlin-Bicêtre, and Institut de Cancérologie Gustave Roussy, 39 rue Camille Desmoulins, 94805 Villejuif, France
BMC Cancer 2010, 10:196 doi:10.1186/1471-2407-10-196
Published: 12 May 2010Abstract
Background
Chromophobe renal cell carcinoma (chRCC) and renal oncocytoma are two distinct but closely related entities with strong morphologic and genetic similarities. While chRCC is a malignant tumor, oncocytoma is usually regarded as a benign entity. The overlapping characteristics are best explained by a common cellular origin, and the biologic differences between chRCC and oncocytoma are therefore of considerable interest in terms of carcinogenesis, diagnosis and clinical management. Previous studies have been relatively limited in terms of examining the differences between oncocytoma and chromophobe RCC.
Methods
Gene expression profiling using the Affymetrix HGU133Plus2 platform was applied on chRCC (n = 15) and oncocytoma specimens (n = 15). Supervised analysis was applied to identify a discriminatory gene signature, as well as differentially expressed genes. High throughput single-nucleotide polymorphism (SNP) genotyping was performed on independent samples (n = 14) using Affymetrix GeneChip Mapping 100 K arrays to assess correlation between expression and gene copy number. Immunohistochemical validation was performed in an independent set of tumors.
Results
A novel 14 probe-set signature was developed to classify the tumors internally with 93% accuracy, and this was successfully validated on an external data-set with 94% accuracy. Pathway analysis highlighted clinically relevant dysregulated pathways of c-erbB2 and mammalian target of rapamycin (mTOR) signaling in chRCC, but no significant differences in p-AKT or extracellular HER2 expression was identified on immunohistochemistry. Loss of chromosome 1p, reflected in both cytogenetic and expression analysis, is common to both entities, implying this may be an early event in histogenesis. Multiple regional areas of cytogenetic alterations and corresponding expression biases differentiating the two entities were identified. Parafibromin, aquaporin 6, and synaptogyrin 3 were novel immunohistochemical markers effectively discriminating the two pathologic entities.
Conclusions
Gene expression profiles, high-throughput SNP genotyping, and pathway analysis effectively distinguish chRCC from oncocytoma. We have generated a novel transcript predictor that is able to discriminate between the two entities accurately, and which has been validated both in an internal and an independent data-set, implying generalizability. A cytogenetic alteration, loss of chromosome 1p, common to renal oncocytoma and chRCC has been identified, providing the opportunities for identifying novel tumor suppressor genes and we have identified a series of immunohistochemical markers that are clinically useful in discriminating chRCC and oncocytoma.