Effect of diethylaminoethyl-dextran on colony formation of human tumor cells in semisolid suspension cultures.

The effect of diethylaminoethyl-dextran on colony formation of established and primary human ovarian and breast tumor cells in semisolid suspension cultures was investigated. At the concentration of 250 to 300 micrograms/ml used in the human tumor stem cell assay, diethylaminoethyl-dextran inhibited in vitro growth of 3 of 4 human breast tumor cell lines and of 10 of 19 primary tumors. It did not affect growth in 7 primary tumors and enhanced colony formation in 2 tumors. We suggest that diethylaminoethyl-dextran may interact in the human tumor stem cell assay with other sites additional to sulfuric acid residues of the agar and that these effects may cancel or outweigh its purported beneficial effects.