Transcriptome analysis of endometrial cancer identifies peroxisome proliferator-activated receptors as potential therapeutic targets Cathrine M. Holland, 1,2 Samir A. Saidi, 2 Amanda L. Evans, 1 Andrew M. Sharkey, 1 John A. Latimer, 2 Robin A.F. Crawford, 2 D. Stephen Charnock-Jones, 2 Cristin G. Print, 1 and Stephen K. Smith 1,2 Departments of 1 Pathology and 2 Obstetrics and Gynaecology, University of Cambridge, The Rosie Hospital, Cambridge, United Kingdom Abstract Endometrial cancer is the most common gynecologic ma- lignancy, frequently arising in association with obesity and diabetes mellitus. To identify gene pathways contributing to endometrial cancer development, we studied the trans- criptome of 20 endometrial cancers and 11 benign endo- metrial tissues using cDNA microarrays. Among the transcript changes identified in endometrial cancer were up-regulation of the nuclear hormone receptors peroxi- some proliferator-activated receptors (PPAR) A and ;, whereas retinoid X receptor B was down-regulated. To clarify the contribution of PPARA to endometrial carcino- genesis, we did experiments on cultured endometrial carcinoma cells expressing this transcript. Treatment with fenofibrate, an activating ligand for PPARA, significantly reduced proliferation and increased cell death, suggesting that altered expression of nuclear hormone receptors involved with fatty acid metabolism leads to deregulated cellular proliferation and apoptosis. These results support further investigation of members of the PPAR/retinoid X receptor pathway as novel therapeutic targets in endome- trial cancer. [Mol Cancer Ther 2004;3(8):993 – 1001] Introduction Endometrial carcinoma is the most common gynecologic malignancy and comprises 97% of all uterine cancers (1). There is a peak incidence between ages 55 and 65 years, with <5% of endometrial cancers occurring below age 40 years (2). The majority are of an endometrioid histologic subtype and display an association with obesity and diabetes mellitus (2). There is a pressing need to better understand the molecular basis for this disease, as 25% of women present with extrauterine disease with 5-year survival rates of f 31% and 10% for Federation Internationale des Gynaecologistes et Obstetristes stages 3 and 4 disease, respectively (2). An improved understanding of events at a molecular level is essential in the development of tar- geted therapy, with a view to improving survival and cure rates. There are increasing efforts to gain a more global view of the multiple, interrelated molecular changes that occur during tumorigenesis (3 – 6). The gene microarray is a high- throughput technology able to interrogate multiple genetic changes within tissues and cells (7 – 9). Consequently, there has been a marked increase in the use of microarrays to interrogate cancers at the genomic level. In addition to screening for candidate genes, microarrays may provide molecular diagnoses, thus avoiding some of the weak- nesses of conventional diagnostic techniques (4, 10). Despite the increasing use of microarray technology in cancer research, there have been difficulties obtaining meaningful biological information. The cost of genome- wide, commercially available arrays may prohibit large experimental samples, and there are multiple sources of variation in experimental results complicating data analysis and interpretation (11). Large-scale gene expression anal- yses of endometrial cancer have mostly been confined to small sample sets and cell lines (12, 13) and have employed genome-wide, commercially available microarray systems (12). Previous microarray studies in endometrial cancer have highlighted differences in the abundance of individ- ual genes between benign and malignant tissues (12, 13), although there has been little advance in the understanding of pathway-specific alterations that may contribute to endometrial tumorigenesis. Independent component anal- ysis (ICA) is a sophisticated statistical method that aims to identify patterns of coregulated genes rather than individ- ual transcript changes (14). We previously have applied high-density cDNA microarrays to determine gene tran- script abundance in epithelial ovarian cancer (14). Materials and Methods Tumor Samples and RNA Preparation Twenty frozen endometrial carcinoma tissues, three atypical complex hyperplasias, and eight postmenopausal benign endometrial control tissues (four atrophic and four Received 3/30/04; revised 5/4/04; accepted 5/14/04. Grant support: Medical Research Council Clinical Training Fellowship G84/5733 (C.M. Holland), Medical Research Council Program grant G9623012 (S.K. Smith and D.S. Charnock-Jones), and Raymond and Beverly Sackler Award (C.M. Holland). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Requests for reprints: Cathrine M. Holland, Department of Obstetrics and Gynaecology, University of Cambridge, The Rosie Hospital, Box 223, Level 2, Robinson Way, Cambridge CB2 2SW, United Kingdom. Phone: 44-1223-336874; Fax: 44-1223-215327. E-mail: cath.holland@obgyn.cam.ac.uk Copyright C 2004 American Association for Cancer Research. Molecular Cancer Therapeutics 993 Mol Cancer Ther 2004;3(8). August 2004