Leukemia cell lines: in vitro models for the study of chronic myeloid leukemia.

The clinical importance of CML lies in its poor responsiveness to chemotherapy which has proved highly effective in treating ALL. The scientific importance of CML resides in its role as a cancer prototype, permitting the identification of genes centrally involved in both neoplastic change and normal cellular differentiation. One of these genes, the fusion gene BCR/ABL resulting from the balanced translocation (9;22) has received wide attention owing to its intimate involvement in CML. Although a tremendous amount of data have been recently discovered about BCR/ABL, its exact role in leukemogenesis and normal hematopoiesis remains obscure. The study of CML cell lines has already been of considerable help in understanding the molecular events associated with the Ph chromosome [4]. Further advances are likely to be forthcoming, particularly at the molecular genetic, but also at the protein level. CML cell lines may offer an excellent means of addressing many issues as continuous cell lines represent an inexhaustible source of identical cell material that, in addition, can be made available to other researchers around the world. This overview on the thus far reported CML-derived cell lines supports the hypothesis that in some specimens of CML the target cells in which Ph translocation arises are not necessarily lineage-restricted committed progenitor cells, but are in fact in some (or all?) cases precommitted bipotential or multipotential progenitor or stem cells retaining the potential for differentiation in diverse hematopoietic directions [26]. In conclusion, established tumor cell lines with their unique phenotypic and karyotypic features have been extremely useful models for investigation of the molecular and biological characteristics of CML. Considerable progress in understanding the molecular and cell biology of CML has been achieved. Further advances in the knowledge of CML are expected to accrue with the productive use of these powerful research tools for many important unresolved issues. By so doing, these discoveries might open new avenues that promise to move clinicians closer to the goal of the prevention or cure of CML in all patients.