In Vitro Cytotoxicity of cis[((1R, 2R)-1, 2-Cyclohexanediamine-N, N')bis(myristato)] platinum(II) Suspended in Lipiodol in Rat Hepatoma AH-109A Cells and Human Tumor Cell Lines

SM-11355, cis[((1R, 2R)-1, 2-Cyclohexanediamine-N, N')bis(myristato)] platinum(II), is a lipophilic platinum complex.SM-11355 suspended in Lipiodol (SM-11355/Lipiodol) was shown to have antitumor activity against hepatic tumors after intra-hepatic arterial administration in animal models. In this study, the in vitro growth inhibitory activities of SM-11355 and ciSplatin (CDDP) following 7-d drug exposure were examined using rat ascite hepatoma AH-109A cells and various human tumor cell lines. In monolayer or suSpension cell cultures, SM-11355 did not inhibit the cell growth, whereas SM-11355/Lipiodol had dose-dependent growth inhibitory activities, as did CDDP suspended in Lipiodol (CdDP/Lipiodol). This was also the case in the colony formation assay in agarose gel. CDDP/Lipiodol released platinum compound into the culture medium rapidly, whereas SM-11355/Lipiodol released it slowly but constantly for 7 d. Furthermore, a significant amount of platinum was detected in the cells treated with CDDP/Lipiodol and SM-11355/Lipiodol. These results suggest that Lipiodol plays an important role in the in vitro cytotoxicity of SM-11355, and certain platinum compounds released from SM-11355/Lipiodol have growth inhibitory effects on these cells.