Abstract LB-263: Identification of gene-expression modifications related to the tumor engraftment in patient-derived xenograft models of solid tumors

Objectives. Establishment of pre-clinical models which reflect molecular alterations of primary tumour is a major goal in cancer research. In order to identify novel therapeutic targets and new treatment, xenografts models are powerful tools to analyse pathways and genes involved in carcinogenesis. The aim of this study is to compare gene expression profilings of 4 cancer types (breast, colon, ovary cancer and uveal melanoma) for which primary tumors (PT) and corresponding xenografts (PTDX) are available. We will highlight differentially expressed gene-sets and pathways involved in stromal environment, cancer cells environment, engraftment process and cancer specific development. In addition, this characterisation was associated to survival analysis in breast cancer. Materials and Methods. Gene expression profiling have been determined using Affymetrix technology. Breast cancer dataset was composed of 8 patient/xenograft paired models corresponding to 16 samples, colon, ovary and uveal melanoma datasets was composed of 24, 11 and 12 paired models respectively. Differential analysis between patients and corresponding xenografts was performed on difference matrix (PTDX-PT). Differentially expressed genes were those with a difference unequal to 0. In order to better identified our gene lists, we analysed large public tumors and cell lines datasets. Results. Comparison between PT and corresponding PTDX identified 150 genes always differentially expressed in the different cancer datasets. A large part are down regulated in PTDX. These genes could be divided into two different environments, immunity on one side and angiogenesis, cellular adhesion and development on the other side. Twenty percent are up-regulated and were mainly associated to cell cycle. A large patient and cell lines collections were used for each cancer type in order to differentiate stromal dependant genes and tumor specific genes. A large part of genes were stromal dependant. However some of them presented same expression between patients and cell lines and are lightly deregulated in mice. Survival and response treatment analysis were performed in breast data. In this cancer, genes related to angiogenesis, cellular adhesion and development were associated to survival. Discussion. This descriptive work based on microarray gene-expression profiling allowed to present common genetic background in four different cancer types and increase knowledge in gene micro-environment in carcinogenesis. This study will then focus on breast cancer and we will characterize patient tumors with high probability to grow into mice in order to concentrate on the response to treatment and improve patient management strategies. Citation Format: Cécile Laurent, Elisabetta Marangoni, Philippe Hupé, Fariba Némati, Nathalie Cassoux, David Gentien, Oumou Goundiam, Virginie Dangles-Marie, Sophie Piperno-Neumann, Pascale Mariani, Didier Decaudin, Laurence Desjardins, Xavier Sastre, Sergio Roman-Roman, Fabien Reyal. Identification of gene-expression modifications related to the tumor engraftment in patient-derived xenograft models of solid tumors. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-263. doi:10.1158/1538-7445.AM2013-LB-263