c-myc Gene in a murine plasmocytoma without visible chromosomal translocations moves to chromosome 12f1 with pvt-1 and rearranges with IgH enhancer-Sμ sequences

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Abstract
The DCPC 21 plasmocytoma lacks any of the MPC‐associated chromosomal translocations. However, the c‐myc gene has been transposed to the IgH locus on chromorome 12 by an Ig switch‐region‐mediated recombination mechanism. DNA sequencing analysis, further, revealed that this recombination is consistent with an insertion of the IgH enhancer (Eμ)‐Sμ sequences, 2341 bp in length, into the c‐myc 5′‐flanking region, resulting in 5′: c‐myc 5′‐flanking‐Eμ‐Sμ‐c‐myc 5′‐flanking‐c‐myc exon‐1 : 3′ segment. In situ molecular hybridization of DCPC 2I metaphase chromosome spreads using a Pvt‐1 probe demonstrated that Pvt‐1 has also moved to the FI sub‐band region of chromosome I2 where the IgH genes are located. These results indicate that the c‐myc gene has been inserted into the IgH locus together with the Pvt‐I, regardless of whether plasmocytoma has cytogenetically identifiable translocations. The possible interaction between c‐myc activation and Pvt‐I in the development of MPCs is discussed.