Establishment of a myeloid leukemia cell line, TRL-01, with MLL-ENL fusion gene

We established a leukemia cell line derived from therapy-related acute myeloid leukemia with the t(11;19) by xenotransplantation into the NOD/SCID mouse with IL-2Rγc−/− (NOG mouse). The cell line, TRL-01, could be serially transplanted from mouse to mouse and also grown in an adherence-dependent manner on a murine bone marrow stroma cell line, HESS-5. TRL-01 had the same immunophenotype as the original leukemia cells: positive for CD13, CD33, CD11a, CD18, CD29, CD49d, CD49e, CD54, CD62L, and CD117, and negative for CD3, CD4, CD8, CD19, CD34, CD41a, CD41b, CD135, and myeloperoxidase. Translocation (11;19)(q23;p13) in both the original sample and TRL-01 generated MLL-ENL chimeric transcripts joining exon 6 and exon 4, respectively, which has a novel isoform. In cultures of TRL-01, addition of GM-CSF, SCF, and G-CSF and adhesion to fibronectin-coated plates promoted transient proliferation and survival, although they did not support long-term culture. Subcutaneous injection caused a tumor to form only when HESS-5 was coinjected at the same site. These results suggest that TRL-01 is a useful cell line for studying not only the leukemia-related biology of MLL-ENL but also the intercellular association between leukemia and stroma.