Yuehchukene, a bis-indole alkaloid, and cyclophosphamide are active in breast cancer in vitro

Yuehchukene (YCK) is a novel bis-indole alkaloid with weak estrogenic activ ity. Biochemical studies showed that YCK could attenuate estrogenic action. In this study, the response of MCF-7 an estrogen-receptor positive breast cancer cell line, under different combinations of estradiol, cyclophosphami de and YCK, was tested. From the dose-response curve, we discovered that 10 (-2) M cyclophosphamide, even in its so-called 'bio-inert' form, could inhi bit MCF-7 cell growth. However, the cytotoxic effect of cyclophosphamide wa s lost by reducing its concentration to similar to 1 x 10(-3) M. On the oth er hand, a low concentration (similar to 10(-8)-10(-9) M) of YCK was found to potentiate the cytotoxic effect of cyclophosphamide on the MCF-7 cell li ne. Such an effect was absent in the estrogen-receptor-negative cell line M DA-MB-231. These findings, together with the dual role of a mixed estrogen and anti-estrogen effect, suggested that YCK and cyclophosphamide can be a potential combination in chemohormonal therapy for breast cancer. Copyright (C) 2000 S. Karger AG, Basel.