Abstract 4310: Gene expression analysis of axial and appendicular osteosarcoma in the canine model

Abstract

Abstract Spontaneously occurring canine osteosarcoma (OSA) is considered an excellent model of the human disease. Canine axial and appendicular osteosarcoma appear histopathologically identical. The clinical course of the two forms, however, seems to diverge. Following surgery, the axial form may be associated with a lower metastatic rate and longer survival than the appendicular form. Identifying gene expression profiles associated with decreased metastatic potential may be crucial for the development of targeted therapies for the human disease. We hypothesized that there are distinct gene expression patterns for canine axial and appendicular OSA. Six axial osteosarcoma tumor samples and six age, breed, and weight matched appendicular osteosarcoma clinical tumor samples were selected from the Center for Comparative Oncology, Michigan State University tissue bank. RNA extraction, amplification and labeling were performed using standard techniques. Raw gene expression values were obtained using the Affymetrix GeneChip Canine Genome 2.0 Array. Background correction, normalization, PM correction, summarization, and expression analysis were performed using the R software with the affy/limma/sva packages. Gene set enrichment analysis was performed using GSEA software. All RNA samples passed quality control and were included in the data set. The expression analysis took into account RNA degradation, which was similar in all tumor samples. A total of 184 genes were differentially expressed by >16-fold, between the two groups. Surrogate variable analysis did not result in any statistically significant differences in gene expression. Gene set enrichment analysis resulted in 9 gene sets enriched in axial, and 4 gene sets enriched in appendicular osteosarcoma samples at FDR < 25%. Gene ranking was similar between the two methods of analysis, with MMP1, ATP6AP1, SLC6A8, and dysadherin expression increased in axial tumor samples, while ICAM2 expression increased in appendicular samples. Expression analysis indicates no statistically significant differences in gene expression between the axial and appendicular OSA. Gene set enrichment analysis indicates potential differences in gene set enrichment between the two types of osteosarcoma. Further quantitative RT-PCR analysis is required to confirm our results. These data will guide hypothesis-driven translational studies, which may have direct clinical implications on the treatment of osteosarcoma. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4310. doi:10.1158/1538-7445.AM2011-4310