Nonrandom fusion of L-plastin(LCP1) and LAZ3(BCL6) genes by t(3;13)(q27;q14) chromosome translocation in two cases of B-cell non-Hodgkin lymphoma.

The LAZ3(BCL6) gene on chromosome band 3q27 is nonrandomly disrupted in B-cell non-Hodgkin lymphoma (B-NHL) by chromosomal translocations clustered within a 3.3-kb MTC (major translocation cluster) located between the two first noncoding exons. These translocations generally result in the expression of a chimeric mRNA transcript between the LAZ3 gene and sequences derived from the partner chromosome. Using RACE RT-PCR, we previously demonstrated fusion of LAZ3 with the RhoH/TTF gene, a hemopoietic cell-specific small GTPase involved in cytoskeleton organization, and with the BOB1/OBF1 gene, a B-cell-specific coactivator of octamer-binding transcription factors, following translocations t(3;4)(q27;p13) and t(3;11)(q27;q23), respectively. Here we report the identification of the L-Plastin(LCP1) gene as a novel LAZ3 partner in chimeric transcripts resulting from a t(3;13)(q27;q14) translocation, in two cases of B-cell lymphoma. As a consequence of the translocation, the 5' regulatory region of each gene was exchanged, creating both LCP1-LAZ3 and reciprocal LAZ3-LCP1 fusion transcripts in one case, and only a LCP1-LAZ3 fusion transcript in the other. The 13q14 chromosome region is frequently disrupted in various proliferative disorders, and the LCP1 gene defines a new breakpoint site in this region. This gene encodes an actin-binding protein and is the second LAZ3 partner gene, with the RhoH/TTF gene, involved in actin cytoskeleton organization. Genes Chromosomes Cancer 26:97-105, 1999.