Abstract B16: Genomic, genetic, and gene expression profile characterization of a panel of primary human uveal melanoma xenografts.
Authors: Laurent Cecile , Nemati Fariba , Gentien David , Desjardins Laurence , Mariani Pascale , Rapinat Audrey , Sastre-Garau Xavier , Hego Caroline , Couturier Jerome , Piperno-Neumann Sophie , Roman-Roman Sergio , Barillot Emmanuel , Saule Simon , Decaudin Didier 
Published: June 2012

Background: Uveal melanoma (UM), which is the most common primary malignancy of the eye in adults, is marked by the occurrence of non resectable liver metastases in about 50% of patients, without any curative treatment. New therapeutic strategies are therefore warranted, and require to be evaluated in relevant and predictive preclinical models in this rare tumor. Primary human cancer xenografts, directly obtained from patient's tumors, constitute such models available for pharmacological assessments. We have developed a panel of 16 UM xenografts obtained from intraocular or metastatic tumor lesions and performed a first comparative characterization with their corresponding patient's tumors (Némati et al, CCR 2010). In this study, we have completed this characterization by the determination of their genomic, genetic, and gene expression profiles.

Materials and methods: Sixteen UM xenografts at very early (P1), early (P4), and late (P9) in vivo passages and their corresponding patient's tumors have been included in the study. After extraction, available DNA/RNA tumor samples were hybridized and scanned at the Institut Curie microarray core facility. Affymetrix GeneChip® Genome-Wide Human SNP6.0 arrays and protocols were used for DNAs, and Affymetrix GeneChip® Human Exon 1.0 ST arrays and protocols for RNA. Gene mutations of GNAQ, GNA11, and BRAF were detected on tumors, metastasis, xenografts, and derived cell lines by PCR, de novo sequencing using forward and reverse primers (BigDye v1.1, Life Technologies) and capillary electrophoresis on GNAS and GNA15 were screened on tumors and xenografts when mutation of GNAQ, and GNA11 were not seen.

Results: Detection of copy number alterations revealed chromosomal aberrations of high risk data sets, including loss of chromosome 1p (46%), gain of 1q (56%), loss of 3 (73%), gain of 6p (37%), loss of 6q (75%), gain of 8q (80%), and multiple genomic alterations in 31/42 samples (73%). Comparison of patient's tumors and corresponding xenografts showed high similarities, with a total correlation score of 0.89. Among the 22517 studied genes, about 3% were differentially expressed between patient's tumors and their corresponding xenografts, in which 2 thirds due to the loss of the human stroma cells during the in vivo transplantation process. The remaining third is due to genes up-expressed in xenografts and related to mitosis, DNA repair, and kinase activity. No differentially expressed genes were found between xenografts at different passages. Finally, with total concordance between patient's tumors and xenografts, GNAQ, GNA11, and BRAF genes were found to be mutated in 31%, 62%, and 0%, respectively.

Conclusion: Genomic, genetic, and gene expression profile characterization of our primary human UM xenografts showed a high conservation of their molecular features during their in vivo transplantation process and in vivo maintain into mice. We therefore consider that they constitute relevant preclinical tools for pharmacological experiments.

Reference:

1. Némati et al. Clin Cancer Res 2010;16:2352–2362.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B16.