In vitro effects of the activity of novel platinum (II) complex in canine and human cell lines

The anticancer activity of novel platinum derivative, a complex of platinum with tris(2-carboxyethyl)phosphine (Pt-TCEP), has been evaluated in canine (D-17) and human osteosarcoma (U2-OS) cell lines. Viability of cells after incubation for 24 or 72 hours with increasing concentrations (0.625, 1.25, 2.50, 5, 10 and 20 mu M) of Pt-TCEP was tested in an MTT assay and compared to effect of cisplatin. Longer-term effect of Pt-TCEP was evaluated in the colony-forming unit assay after 24 hours exposure to the Pt-TCEP (2 and 3 mu M) and subsequent incubation for 2 weeks. The influence of the compound on the cell cycle was measured after 24 hours treatment with Pt-TCEP (3 mu M). Its pro-apoptotic activity was examined after 24 hours treatment with Pt-TCEP (1.25, 2.50, 5, 10 and 20 mu M) using flow cytometry. Expression of main proteins involved in apoptosis was measured after exposure for 24 hours to 3 or 5 mu M Pt-TCEP in Western Blot. The compound much more effectively decreased cell viability than cisplatin in case of both cell lines. IC50 of Pt-TCEP was 5.93 +/- 0.12 in D-17 and 3.45 +/- 0.14 in U2-OS cell lines after 24 hours, and 1.77 +/- 0.14 in D-17 and 1.53 +/- 0.11 in U2-OS after 72 hours (P < .05). The compound arrested cells in the G2/M phase and inhibited the ability of cells to form colonies. Pt-TCEP induced caspase-dependent apoptosis. The expression of the anti-apoptotic Bcl-X-L protein was decreased after Pt-TCEP treatment in both cell lines. The results confirmed anti-cancer activity of Pt-TCEP against canine and human osteosarcoma cell lines.