Chloroquine Inhibits Self-Renewal of Blast Progenitors Synergistically With Phytochemicals or Nonsteroidal Anti-inflammatory Drugs in Hematological Malignant Cell Lines

BACKGROUND: This study examined whether and how chloroquine inhibits blast progenitor self-renewal (SR) synergistically with phytochemicals or nonsteroidal anti-inflammatory drugs in seven hematological malignant cell lines. MATERIALS AND METHODS: Vitamin C, resveratrol, cyclo-oxygenase inhibitor NS-398 and indomethacin heptyl ester (Ind) were added to cell culture with or without 3 μM chloroquine. RESULTS: Chloroquine synergistically inhibited blast colony formation in methylcellulose with vitamin C, resveratrol, NS-398 and Ind in one, two, none and one cell lines, respectively, in a total of four out of 28 conditions. Chloroquine synergistically inhibited blast progenitor SR in suspension with vitamin C, resveratrol, NS-398 and Ind in four, six, one and five cell lines, respectively, in a total of 16 out of 28 conditions. In contrast, chloroquine abolished SR inhibition by another agent in four out of 28 conditions. CONCLUSION: Chloroquine exerted a marked synergistic inhibition of blast progenitor SR, but not blast colony formation.