Abstract
Doxorubicin (DOX) is a potent anticancer agent, the use of which is limited by its cumulative dose-dependent cardiotoxicity. Pentoxifylline (PTX) is a non-toxic methylxanthine used clinically for the treatment of intermittent claudication. It is an active haemorheological agent, used for the treatment of defective microcirculation. In the present study, we employed PTX as a drug response modulator in combination with DOX to achieve increased cytotoxicity in human chronic myeloid leukemia (CML) cells. Inhibition of H-TdR incorporation was used as a measure of cytotoxicity. PTX at lOOuM concentration significantly (P < 0.001) potentiated DOX-mediated DNA biosynthesis inhibition in CML cells in vitro. Significant synergistic inhibition was seen in 13 out of 22 CML samples. Decreased DOX accumulation is a characteristic feature of DOX resistant tumor cell lines. Drug accumulation studies demonstrated that PTX significantly (P < 0.02) increased the intracellular accumulation of DOX in the CML cells. The enhanced DOX accumulation can be a mechanism of increased cytotoxicity by DOX-PTX combination.
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