Remarkable induction of apoptosis in cancer cells by a novel cationic liposome complexed with a bcl-2 antisense oligonucleotide.

We reported recently a novel cationic cholesterol derivative with a hydroxyethylamino head group, cholesteryl-3beta-carboxyamidoethylene-N-hydroxyethylamine (I) for liposome-mediated gene transfection [FEBS Lett., 408 (1997) 232]. In the present paper we have studied whether this novel cationic liposome is prominent in nature to suppress cell growth of human cancer cells. Bcl-2 antisense phosphorothioate oligonucleotides (AS-ODNs) were complexed with the cationic liposomes with the derivative (I) and they were introduced into human cervix epithelial carcinoma cell lines HeLa, and mouse fibroblast NIH3T3 cells. An AS-ODNs targeting/bcl-2 gene induced probably apoptosis (including necrosis in some cases) in HeLa and NIH3T3 cells, however, nonsense oligonucleotides (NS-ODNs) corresponding to a scrambled-sequence control hardly induced apoptosis. Induction of apoptosis was much greater than that by commercially available DC-Chol liposomes. Fluorescence intensities of FITC-conjugated bcl-2 AS-ODNs were specifically found in the nucleus. The intensity of the AS-ODNs was mostly consistent with the amounts of Bcl-2 proteins observed by Western blot analysis in the target cells. The results showed the possibility that this new cationic cholesterol derivative might be very promising to be used for liposome-mediated gene targeting in vitro and in vivo.