N. S. Finiuk^1,2, Yu. V. Ostapiuk², V. P. Hreniukh², Ya. R. Shalai²,
V. S. Matiychuk², M. D. Obushak², R.S. Stoika¹*, A. M. Babsky²**

¹Institute of Cell Biology, National Academy of Sciences of Ukraine, Lviv;
²Ivan Franko National University of Lviv, Ukraine;
*e-mail: stoika@cellbiol.lviv.ua; **e-mail: andriy.babsky@lnu.edu.ua

The research aim was to test cytotoxic effects in vitro of seven novel pyrazolothiazolopyrimidine derivatives in targeting several lines of tumor and pseudo-normal mammalian cells. We demonstrated that cytotoxic effects of these derivatives depended on the tissue origin of targeted cells. Leukemia cells were found to be the most sensitive to the action of compounds 2 and 7. Compound 2 demonstrated approximately two times higher toxicity towards the multidrug-resistant sub-line of HL-60/ADR cells compared to the Doxorubicin effect. Antiproliferative action of compounds 2 and 7 dropped in the order: leukemia > melanoma > hepatocarcinoma > glioblastoma > colon carcinoma > breast and ovarian carcinoma cells. These compounds were less toxic than Doxorubicin towards the non-tumor cells. The novel pyrazolothiazolopyrimidine, compound 2, demonstrated high toxicity towards human leukemia and, of special importance, towards multidrug-resistant leukemia cells, and low toxicity towards pseudo-normal cells.