Svi3: A provirus common integration site in c‐myc in SL/Kh pre‐B lymphomas

Open Access
Publisher Website
Google Scholar
Abstract
Spontaneous pre‐B lymphomas in SL/Kh mice occur by somatic acquisition of a provirus genome of endogenous murine leukemia virus (MuLV). Inverse PCR amplification and sequence analyses of a provirus and its host flanking fragment revealed a proviral insertion into c‐myc in 3 out of 60 SL/Kh pre‐B lymphomas, named Svi3 lymphomas (SL/Kh virus integration site‐3). Southern blot analysis revealed that two lymphomas had clonal integration in c‐myc exon 1 and the other, in the promoter region. In 2 out of 3 Svi3 lymphomas, a fusion transcript of provirus 3’long terminal repeat and c‐myc and a normal full‐length c‐myc transcript were obtained, but in one Svi3 lymphoma, only the normal transcript was obtained. All three Svi3 lymphomas had increased c‐myc expression, producing normal 67‐kDa c‐Myc protein. Svi3 lymphomas had more mature phenotypes in the steps of early B‐cell differentiation than Svi 1 lymphomas, in which c‐myc expression was indirectly up‐regulated by provirus integration into Stat5a.