Value Identified through Transcriptome Analysis Novel Glioblastoma Markers with Diagnostic and Prognostic

Purpose: Current methods of classification of astrocytoma based on histopathologic methods are often subjective and less accurate. Althoughpatients with glioblastomahave graveprognosis, significant variability in patient outcome is observed. Therefore, the aim of this study was to identify glioblastoma diagnostic and prognostic markers throughmicroarray analysis. Experimental Design:We carried out transcriptome analysis of 25 diffusely infiltrating astrocytoma samples [WHO grade II diffuse astrocytoma, grade III anaplastic astrocytoma, and grade IV glioblastoma (GBM)] using cDNA microarrays containing 18,981genes. Several of the markers identified were also validated by real-time reverse transcription quantitative PCR and immunohistochemical analysis on an independent set of tumor samples (n = 100). Survival analysis was carried out for two markers on another independent set of retrospective cases (n = 51). Results: We identified several differentially regulated grade-specific genes. Independent validation by real-time reverse transcription quantitative PCR analysis found growth arrest and DNA-damage ^ inducible a (GADD45a) and follistatin-like1 (FSTL1) to be up-regulated inmost GBMs (both primary and secondary), whereas superoxide dismutase 2 and adipocyte enhancer binding protein 1were up-regulated in the majority of primary GBM. Further, identification of the grade-specific expression of GADD45a and FSTL1by immunohistochemical staining reinforced our findings. Analysis of retrospective GBM cases with known survival data revealed that cytoplasmic overexpression of GADD45a conferred better survival while the coexpression of FSTL1with p53 was associated with poor survival. Conclusions: Our study reveals that GADD45a and FSTLI are GBM-specific whereas superoxide dismutase 2 and adipocyte enhancer binding protein1are primary GBM-specific diagnostic markers.Whereas GADD45a overexpression confers a favorable prognosis, FSTL1 overexpression is a hallmark of poor prognosis in GBM patients. Diffuse-infiltrating astrocytomas include the following entities: (a) diffuse astrocytoma (DA; WHO grade II), (b) anaplastic astrocytoma (AA; WHO grade III), and (c) glioblastoma (GBM; WHO grade IV). AA and GBMs constitute malignant astrocytomas and are the most common intrinsic central nervous system neoplasms (1). The prognosis of patients with these tumors is dismal, and GBM, which is the most malignant phenotypic variant, has a mean survival of 10 to 12 months (2). Currently available treatment options are multimodal, which include surgery, radiotherapy, and chemotherapy. However, these have been shown to improve survival onlymarginally inGBMpatients. The development of GBM has been described to occur through at least two genetic pathways resulting in the formation of primary and secondary GBMs (3). Primary GBM represents the most frequently presenting variant occurring de novo without an evidence of a less malignant precursor. Imaging, Diagnosis, Prognosis Authors’: Affiliations: Departments of Molecular Reproduction, Development and Genetics, Microbiology andCell Biology, and Biochemistry, Indian Institute of Science; Manipal Hospital; Department of Neuropathology andNeurosurgery, National Institute ofMentalHealthandNeurosciences; Sri SatyaSai Institute ofHigherMedical Sciences; andJawaharlalNehruCentre forAdvancedScientificResearch,Bangalore, India Received11/5/07; revised 2/5/08; accepted 2/17/08. Grant support:CouncilofScientificandIndustrialResearch,GovernmentofIndiaunder the NewMillennium IndianTechnology Leadership Initiative program. K. Somasundaram is aWellcomeTrust International senior research fellow. Infrastructural support by funding from the Indian Council of Medical Research-Center forAdvanced Studies inMolecular Medicine, Department of Biotechnology, Department of Science andTechnology (Fund for Improvement of Science andTechnology Infrastructure), and University Grants Commision to the Departments of Microbiology and Cell Biology; Molecular Reproduction,DevelopmentandGenetics; andBiochemistry, Indian InstituteofScience. The costs of publication of this article were defrayed in part by the payment of page charges.This articlemust therefore be herebymarked advertisement in accordance with18U.S. C.Section1734solely toindicatethis fact. Note: Supplementary data for this article are available at Clinical Cancer Research Online (http://clincancerres.aacrjournals.org/). S.P. Reddy, R. Britto, and K. Vinnakota contributed equally to this work. Requests for reprints: Kumaravel Somasundaram and Paturu Kondaiah, Indian InstituteofScience,SirC.V. RamanRoad,Bangalore,Karnataka560-012, India.Phone: 91-80-23607171/91-80-22932688; Fax: 91-80-23602697; E-mail: skumar@ mcbl.iisc. ernet.inandpaturu@mrdg.iisc. ernet.in. F2008 American Association for Cancer Research. doi:10.1158/1078-0432.CCR-07-4821 www.aacrjournals. org Clin Cancer Res 2008;14(10) May15, 2008 2978 American Association for Cancer Research Copyright © 2008 on May 19, 2011 clincancerres.aacrjournals. org Downloaded from DOI:10.1158/1078-0432.CCR-07-4821