Chromosomes 1 and 5 harbor plasmacytoma progressor genes in mice

Mouse spectral karyotyping (SKY) was employed to analyze 29 primary BALB/c plasmacytomas (PCTs) for the presence of chromosomal aberrations that took place subsequent to the Myc-activating T(12F1;15D2) or T(6C1;15D2) translocations, the initiating oncogenic mutations in plasmacytomagenesis. Recurrent amplifications of chromosome (Chr) 1 (48% prevalence) and promiscuous non-reciprocal translocations of Chr 5 (52% prevalence) suggested the existence of important PCT progressor genes on bands 1B/C and 5F. The additional occurrence of sporadic aberrations (93% prevalence) most likely reflected the general instability of the PCT genome. This instability, however, was not consistent, as two PCTs lacked secondary cytogenetic changes detectable by SKY. Our findings led us to conclude that BALB/c PCTs show a remarkably similar degree of cytogenetic heterogeneity to human multiple myeloma, despite being genetically defined (inbred mouse strain) and uniformly initiated (deregulation of Myc). Published 2000 Wiley-Liss, Inc.