Antitumoral effects of squamocin on parental and multidrug resistant MCF7 (human breast adenocarcinoma) cell lines

The antiproliferative effects of squamocin, one of the easiest annonaceous acetogenins to obtain, were studied in the parental (MCF7-S) and the multid rug resistant (MCF7-R) human breast adenocarcinoma cell lines. Squamocin in hibited proliferation of both cell lines identically, by blocking the cell cycle in the G1-phase. This inhibition was reversible in the long term. Squ amocin decreased the ATP pool in both MCF7 cell lines, but did not seem to induce apoptosis. Cytotoxic activity of adriamycin was not restored in MCF7 -R Pgp expressing cells by squamocin addition.