Altered intracellular transport of exogenous DNA by murine mammary tumor cell lines

Abstract

The uptake of exogenous DNA by a series of murine mammary tumor cell lines was compared with DNA uptake by normal cells and other types of transformed cells. The mammary tumor cell lines all exhibited a decreased efficiency in the transport of DNase-resistant exogenous DNA into the nuclear fraction. None of the DNA facilitators tested were able to surmount this transport defect. Normal mouse mammary gland cells, mouse embryo cells, and normal kidney cells from various species efficiently transported exogenous DNA into the nucleus. Similarly, the transport defect was not exhibited by a series of transformed cell lines, including those of mouse origin and those transformed by C-type oncornaviruses. The only exception was a murine leukemia virus-producing mouse line that displayed decreased nuclear uptake of the DNA. The nature of the exogenous DNA was apparently not a factor, since identical results were obtained with simian virus 40 and mammalian cell DNA's. The inducing agents of the mammary tumor cells also did not appear to be a factor, since cell lines derived from tumors induced spontaneously or by viral, hormonal, or chemical carcinogens all behaved similarly.