Effects of cyclic polylactate (CPL) on the growth of cloned leukemic cellsin vitro

A novel supramolecular oligomer, cyclic polylactate (CPL), was first discov ered in the culture medium of HeLa-S tumour cells, and was reported to inhi bit the growth of FM3A ascites tumour cells by inhibiting the activities of pyruvate kinase (PK) and lactic dehydrogenase (LDH). We have now synthesiz ed CPL-containing oligomers with polymerization numbers ranging from 9 to 1 9, by prolonged heating and rapid mixing of a carbohydrate compound of the L-lactic acid monomer (C3H6O3) under decreased pressure and have studied it s effects on the growth of leukemic cells. Treatment with 0.02 mg/ml CPL in hibited the growth of HL60 and TF-1 cells, while the growth of K562 cells w as inhibited by 0.2 mg/ml CPL. A concentration of 2 mg/ml CPL was required to inhibit granulocyte-macrophage progenitor cell (CFU-GM) and burst-formin g unit erythroid (BFU-E) precursor colony formation among normal bone marro w cells. Furthermore, 7A6 antigen expression and DNA ladder formation were observed in leukemic cells cultured with CPL, indicating that CPL induces a poptotic changes in these cells. These findings suggest that CPL might be a useful chemotherapeutic agent for leukemia. Copyright (C) 2000 John Wiley & Sons, Ltd.