Concurrent activation of a novel putative transforming gene, myeov, and cyclin D1 in a subset of multiple myeloma cell lines with t(11;14)(q13;q32)

Through the application of the NIH/3T3 tumorigenicity assay to DNA from a gastric carcinoma, we have identified a novel transforming gene, designated myeov (myeloma overexpressed gene in a subset of t[11;14]-positive multiple myelomas). Sequence analyses did not reveal any homology with sequences present in the GenBank, except the deduced protein structure predicts a transmembrane localization. Myeov was mapped to chromosome 11q13 and localized by DNA fiber fluorescence in situ hybridization (FISH) 360-kilobase (kb) centromeric of cyclin D1. In 3 of 7 multiple myeloma (MM) cell lines with a t(11;14)(q13;q32) and cyclin-D1 overexpression, Northern blot analysis revealed overexpression of myeov as well. In all 7 cell lines, the translocation breakpoint was mapped within the 360-kb region between myeov and cyclin D1. DNA fiber FISH with a contig of probes covering the constant region of the immunoglobulin heavy chain (IgH) revealed that exclusively in the 3 myeov-overexpressing cell lines (KMS-12, KMS-21, and XG-5), either the 5' Eμ enhancer or the most telomeric 3' Eα enhancer was juxtaposed to myeov. Although cyclin D1 overexpression represents a characteristic feature of all MM cell lines with t(11;14), our results demonstrate aberrant expression of a second putative oncogene in a subset of these cases, due to juxtaposition to IgH enhancers. The clinical relevance of this dual activation remains to be elucidated. (C) 2000 by The American Society of Hematology.