SCL, A GENE FREQUENTLY ACTIVATED IN HUMAN T-CELL LEUKEMIA, DOES NOT INDUCE LYMPHOMAS IN TRANSGENIC MICE

The scl gene is implicated in human T cell acute lymphoblastic leukaem ia (T-ALL) through its involvement in the t(1;14)(p32;q11) chromosomal translocation and, more frequently, as a result of a tumour-specific interstitial deletion on chromosome 1. The consequence of both these c hromosomal alterations is overexpression of scl in the leukaemic cells . Despite the strong inference of a role in human T-ALL, scl has not y et been demonstrated to be causally involved in neoplastic transformat ion. We attempted to do this by generating transgenic mice in which sc l expression was directed to the T cell lineage using the CD2 enhancer and the strong SR alpha viral promoter (CD2-scl mice). Three transgen ic lines, an of which expressed the scl transgene at a high level, wer e bred and analysed. No alterations in T cell development were seen in the mice. Unexpectedly CD2-scl mice did not develop tumours, nor did the transgene enhance tumourigenesis by Moloney murine leukaemia virus . These findings throw into question the mechanism by which aberrant s cl expression contributes to T cell leukaemogenesis.