THE EFFECT OF ALPHA-INTERFERON, BETA-INTERFERON AND GAMMA-INTERFERON ON THE GROWTH OF BREAST-CANCER CELL-LINES

We investigated the antiproliferative effect of different concentratio ns (1O, 100, 1000 IU/ml) of alpha-, beta- and gamma-interferons (IFN) on breast cancer cell lines. Cell lines were treated with IFN, in the absence or in the presence of estrandiol for 9 days, and the effect on growth was evaluated as variation in DNA content. Inhibitory effect v aried as a function of the type of interferon and cell line. Alpha-IFN and gamma-IFN were effective only at 1000 IU/ml and not in all cell l ines, whereas a maximum effect was observed for beta-IFN regardless of the steroid receptor status of cell lines. In fact, a significant gro wth inhibition was observed at the intermediate concentration of 100 I U/ml in all but MDA-MB231 cell lines. Moreover, in both estrogen-recep tor positive cell lines, beta-IFN counteracted growth stimulation indu ced by estradiol and showed a strong antiestrogenic activity. In concl usion, our results show that beta-IFN is the most active among the IFN s tested and suggest its usefulness in the treatment of all breast can cers, irrespective of their steroid receptor status.