Resequencing Analysis of the Human Candidate Ras and Receptor Tyrosine Kinase Gene Family In Multiple Myeloma

Abstract 301

Multiple myeloma (MM) is an incurable B-cell malignancy characterized by the clonal proliferation and accumulation of malignant plasma cells in the bone marrow. Despite the growing number of sequencing studies, the comprehensive view of somatic mutations in multiple myeloma is far from clear. One of the most frequently altered gene families in most human cancer is the Ras and the tyrosine kinase (TK) genes, which encode for important regulators of various signal transduction pathways. To uncover the somatic mutation profile of Ras gene and TKs in myeloma, we performed a systematic mutation screening from a selected group of 10 candidate genes in 42 primary myeloma patients. The candidate gene selections were based on the highly altered genes extracted from GEO data sets using Function Express, a data mining and viewer for microarray data. The sequencing of the entire gene region including the promoter and the 3`UTR was performed in the Genome sequencing center at Washington University medical center using the standard resequencing pipeline, from the design of the primers to data output. These data were analyzed with a clinical resequencing pipeline and visualized using the Mutation Viewer software (MV v5.1). We identified 24 nonsynonymous alterations in five genes (KRAS2, PIK3CA, INSR, LTK and MERTK) in our myeloma cohort (Table 1). In particular, we identified the previously reported pathogenic mutation in a KRAS gene and novel somatic mutations in the Kinase family (PIK3CA) that would be expected to cause structural changes. We assessed the frequency plots of the known variants and most but not all are significantly different from the normal data set. The overall results suggest that the germline genetic background besides the somatically acquired mutations may exert an important influence on the prognosis and outcome of the myeloma patient. Our genome-wide resequencing approach thus revealed previously known and novel oncogenic mutations in multiple myeloma, but its relevance needs to be considered in the context of other genetic abnormalities.