Rearrangement of the human tre oncogene by homologous recombination between Alu repeats of nucleotide sequences from two different chromosomes

The rearranged region of the tre oncogene originating from chromosomes 5q23q31 and 18q12 was cloned from tumor genomic DNA, sequenced and aligned with wildtype sequences cloned from a normal human genomic library. In the breakpoint region each wild-type sequence contained two Alu repeats. The recombination occurred between the 3′-most Alu from chromosome 5 and the 5′-most Alu from chromosome 18 and, consequently, resulted in a hybrid Alu flanked with one Alu on either side. The recombinant joint was located to a 20-bp homology region in left arms of the Alu repeats involved in recombination. The same homology region was identified in the hybrid Alu of the rearranged tre. At its 5′ extremity the homology region overlaps the B box of Ala-borne RNA polymerase III promoter. The 100% identity score in the region of homology suggests that the recombination process was conservative and not error prone.