Comprehensive Genome-Wide Profile of Regional Gains and Losses in Multiple Myeloma Using Array-CGH: The 1q21 Amplification and Potential Role of the BCL-9 Gene in Multiple Myeloma Pathogenesis.

Multiple Myeloma (MM) is characterized by a clonal proliferation of abnormal plasma cells in the bone marrow and is among the most frequent and lethal hematological diseases. In spite of significant effort towards the identification of the molecular events leading to this malignancy, the genetic alterations responsible for the pathogenesis of this disease remain poorly understood. Regional copy number alterations (CNAs) in cancer genomes have been among the most informative structural changes in cancer and have led to the discovery of many oncogenes and tumor supressor genes. Using array comparative genomic hybridization (array-CGH) and expression microarray technologies we have analyzed a large collection of cell lines and clinically annotated primary tumors. This high-resolution genomic analysis has identified all previously reported regional gains and losses as well as many novel highly recurrent genetic loci with potential biological and clinical relevance. In particular, we have identified an amplification at chromosome 1q21 as one of the most recurrent genetic changes in cell lines and in a subgroup of primary tumors. This chromosomal change has been previously implicated with disease progression. Analysis across several cell lines has allowed the identification of a Minimal Common Region (MCRs) of amplification at 1q21. Correlation between DNA copy number changes and expression profiling data has identified a limited set of candidate genes within this MCR that are amplified and overexpressed. Using shRNAi technology we have identified BCL-9 as a candidate gene residing at the 1q21 MCR. In vitro and in vivo functional data about the role of BL-9 will be presented. These data will provide critical understanding on the diverse pathways leading to Multiple Myeloma progression.