Molecular characterization stratifies VQ myeloma cells into two clusters with distinct risk signatures and drug responses [RNA-Seq]
Multiple myeloma (MM) is a cancer of malignant plasma cells in the bone marrow and extramedullary sites. We previously characterized a VQ model for human high-risk MM. Different VQ lines display distinct disease phenotypes and survivals, suggesting significant intra-model variation. Here, we use whole exome sequencing and copy number variation (CNV) analysis coupled with RNA-Seq to stratify VQ lines into corresponding clusters: Group A cells had monosomy chr5 and overexpressed genes and pathways associated with sensitivity to bortezomib (Btz) treatment in human MM patients. By contrast, Group B VQ cells carried recurrent amplification (Amp) of chromosome (chr) 3 and displayed high-risk MM features, including downregulation of Fam46c, upregulation of cancer growth pathways associated with functional high-risk MM, and expression of Amp1q and high-risk UMAS-70 and EMC-92 gene signatures. Consistently, in sharp contrast to Group A VQ cells that showed short-term response to Btz, Group B VQ cells were de novo resistant to Btz in vivo. Our study highlights Group B VQ lines as highly representative of the human MM subset with ultrahigh risk. Overall design: RNA-Seq libraries of MM cells isolated from BM, spleen, LN, liver from multiple recipient mice that received transplantation of VQ-D1, VQ-D2, VQ-D4, VQ-D5, or t-VK12653 donor cells.