MOLECULAR CHARACTERIZATION OF A CHROMOSOME-TRANSLOCATION BREAKPOINT T(11-14)(P13-Q11) FROM THE CELL-LINE KOPT-K1

Recurrent chromosome translocations involving 11p13 and 14q11 are foun d in 5-10% of cases of T-ALL. The gene involved in the translocation o n chromosome 14 is the T cell antigen receptor alpha or delta. The put ative oncogene on chromosome 11 is rhombotin 2 (RBTN2)/translocated in T cell gene 2 (ttg-2), a member of the LIM family of proteins. In thi s paper we characterize a cell line KOPT-K1 that has a t(11;14)(p13;q1 1). The breakpoint on chromosome 11 involves an Alu-rich region with t he break occurring between two Alu sequences on chromosome 11. In addi tion, approximately 70 bases from the break on chromosome 11 is a tetr anucleotide repeat. Whether either of these structures played a role i n the translocation is not known. No heptamer or nonamer sequences, im plicated in other rearrangements were found near the breakpoint. The b reakpoint on chromosome 11 maps more centromeric than previous translo cations of this region. Despite this the RBTN2 gene is highly expresse d in KOPT-K1. This cell line will be useful for investigating the role of RBTN2 in leukemogenesis and the mechanism by which the translocati on alters the expression of RBTN2.