ADENOVIRUS-MEDIATED GENE-TRANSFER TO HUMAN BREAST-TUMOR CELLS - AN APPROACH FOR CANCER GENE-THERAPY AND BONE-MARROW PURGING

To examine the potential use of adenovirus vectors in cancer gene ther apy as a mechanism for purging bone marrow cells of possible breast ca ncer contaminants, we compared the infection efficiency of adenovirus and the transfection efficiency of plasmid DNA in the presence of aden ovirus in human breast cancer and bone marrow cells. Following infecti on of breast cancer cells with an adenovirus expressing beta-galactosi dase gene, high levels of beta-galactosidase activity were observed. N o beta-galactosidase activity was observed in low-density human bone m arrow cells. A replication-deficient adenovirus mutant dI312 enhanced the transfection efficiency of a plasmid DNA-expressing beta-galactosi dase gene into breast cancer cells, and addition of a liposome, lipofe ctamine, further enhanced the transfection efficiency. In contrast, hu man bone marrow cells treated under the same conditions expressed very low levels of the transfected beta-galactosidase DNA. Transfection of cells with plasmid DNA expressing a truncated but fully active Pseudo monas exotoxin gene in the presence of dI312 and lipofectamine resulte d in marked breast cancer cell killing, whereas colony-forming unit gr anulocyte-macrophage (CFU-GM) were relatively resistant to these treat ments. A recombinant adenovirus expressing human wild-type p53 protein (AdWTp53) was also highly cytotoxic to breast tumor cells. Infection of breast cancer cells with AdWTp53 (100 plaque-forming units/cell) re sulted in 100% loss of the clonogenicity of breast tumor cells. Howeve r, colony formation from CFU-GM was relatively resistant to the cytoto xic effects of AdWTp53 alone or in the presence of pULI100 plasmid and lipofectamine. On the basis of these results, it is proposed that hum an adenoviruses are potentially useful for cancer gene therapy and bon e marrow purging.