Abstract 2150: Genetic alterations in the major pathways in human osteosarcoma and their clinical significance

Abstract

Abstract Background Osteosarcoma (OS) is a genetically unstable malignancy that most frequently occurs in children and young adults. It has high incidence of metastasis and recurrence after treatment. The lack of progress in clinical management of this devastating disease prompts us to take a systems approach to profile key genetic alterations at the level of gene copy number aberration on a genome-wide scale and to interrogate the pathways that are critical for the hallmarks of OS. Our goal is to gain insight into potentially novel targets for therapeutics. Methods We conducted a high-density genome-wide array comparative genomic hybridization (aCGH) profiling with genomic DNA isolated from 10 fresh osteosarcoma tissues obtained from the Tumor Tissue Bank of the Tianjin Medical University Cancer Institute and Hospital (GSE19180). In addition, we downloaded aCGH data of an independent investigation from the GEO database (GSE9654). The patterns of the two independent aCGH data showed marked similarities. The pooled aCGH data were subjected to Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis to identify altered pathways. Protein expression of specific genes was examined by immunohistochemistry (IHC) on 58 archival formalin fixed, paraffin embedded (FFPE) tissues and correlated with clinical follow-up information. Results Genome-wide aCGH analysis revealed that 1p35-1p35, 1q23.1-1q21.1, 6p22.1-6p21.31, and 19p13.11-p13.2 were significantly amplified, whereas 5q12.3-5q13.2, 5q14.3-5q22.2, and 13q13.2-13p14.3 were significantly deleted. These regions included 1,162 genes with amplifications and 146 genes with deletions. Pathway analysis showed that a number of cancer related pathways were significantly altered. These pathways included VEGF, cell adhesion, adherins junction, non-homologous end-joining, hedgehog signaling, and Wnt signaling pathways. Among the VEGF pathway genes, 13 genes including VEGFA itself were amplified. Detailed analysis showed that VEGFA protein expression (74.1%) was associated with microvascular density (MVD) (20.81±2.04 per mm2) and was an independent predictor for metastasis and/or recurrence (p=0.01). The aCGH analysis also led to the discovery that the tumor suppressor gene WWOX was deleted in 30% of OS. IHC analysis showed that loss of WWOX protein expression was even more frequent (61.8%), suggesting deletion of WWOX gene and ablated expression might be an important early event in OS pathogenesis. In addition, we found that the APEX1 gene was amplified in 60% in OS and the abundant expression of APEX1 protein (64.9%) was an independent predictor for the local recurrence and/or metastasis (p=0.04). Conclusions The systematic analysis of the genetic alterations has revealed involvement of multiple pathways in the pathogenesis and progression of OS suggesting that multi-pronged combinational therapy is needed for effective therapeutics. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2150.