Pentoxifylline stimulates drug-induced apoptosis in leukemic cells

Camptothecin (CAM) and cisplatin (cis-diamminedichloroplatinum(II), cis-Pt) were used as inducers of apoptosis in the mouse leukemic L1210 cells. Rela tively high concentrations of 50 mu mol cis-Pt and 50 mu mol CAM, respectiv ely, were used to induce the apoptotic DNA ladder. The simultaneous treatme nt of L1210 cells by the drug and pentoxifylline (PTX) resulted in a decrea se of drug concentrations necessary for the induction of apoptosis. This st udy revealed that a cell cycle G(2) checkpoint inhibitor PTX reduces time i ntervals necessary for the onset of drug-induced apoptosis in these cells. This fact might be important as the earlier onset of programmed cell death may decrease a risk of tumor cells to become resistant to drug therapy.