Increased Sensitivity of Myeloid Leukemia Cell Lines: Potential of Lovastatin as Bone-Marrow-Purging Agent

Lovastatin reduces the isoprenylation of p21ras via suppression of mevalonic acid generation. Lovastatin has been shown to reduce tumor cell proliferation in a dosedependent manner. Here, the potential of lovastatin for purging leukemia cells from bone marrow was investigated using the myeloblastic cell lines K562 and KG-1 as a model system, derived from an erythroleukemia and an acute myelogenous leukemia, respectively. Optimal purging conditions were determined using an MTT proliferation and a leukemia colony assay. Elimination of leukemia cells was time- and dosedependent. Depletion of K562 was 2.5 logs for 100 µM of lovastatin at 72 h of incubation. Compared to another purging agent, 100 µg/ml mafosfamide had an activity comparable to 100 mM lovastatin. Interestingly, KG-1 acute myelogenous leukemia cells were even more sensitive to lovastatin than K562 cells. In clonogenic assays, 100 µM of lovastatin resulted in a 3- to 4-log reduction of K562 colonies. Lovastatin had a progressive effect on normal hematopoietic progenitor cells. At a concentration of 100 µM of lovastatin, CFU-GM colonies were reduced by 1-2 logs. In conclusion, a differential effect on leukemia and normal progenitor cells could be detected in a clonogenic assay. These results suggest that lovastatin deserves further study as an agent for ex vivo marrow purging.