Dequalinium, a topical antimicrobial agent, displays anticarcinoma activity based on selective mitochondrial accumulation.

Positively charged lipophilic compounds, such as rhodamine 123, localize in mitochondria and are selectively accumulated and retained by carcinoma cells. It has been suggested that this phenotype may be exploited for selective killing of carcinoma cells by lipophilic cations. Here we report that doubly positively charged dequalinium, which has been used for 30 years as an antimicrobial agent in over-the-counter mouthwashes, lozenges, ointments, and paints, exhibits significant anticarcinoma activity. Dequalinium is more effective than seven of eight established anticancer drugs in prolonging the survival of mice with intraperitoneally implanted mouse bladder carcinoma MB49. Dequalinium also inhibits the growth of subcutaneously implanted human colon carcinoma CX-1 in nude mice and recurrent rat colon carcinoma W163 in rats. Lipophilic cationic compounds, such as dequalinium, could comprise a unique class of anticarcinoma agents.