Consumption of cruciferous vegetables is associated with reduced risk of various types of
cancer.
Isothiocyanates including
sulforaphane and
erucin are believed to be responsible for this activity.
Erucin [1-isothiocyanato-4-(methylthio)
butane], which is metabolically and structurally related to
sulforaphane, is present in large quantities in arugula (Eruca sativa, Mill.), kohlrabi and Chinese cabbage. However, its
cancer preventive mechanisms remain poorly understood. We found that
erucin inhibits proliferation of MCF7
breast cancer cells (IC50 = 28 µM) in parallel with cell cycle arrest at mitosis (IC50 = 13 µM) and apoptosis, by a mechanism consistent with impairment of microtubule dynamics. Concentrations of 5-15 µM
erucin suppressed the dynamic instability of microtubules during interphase in the cells. Most dynamic instability parameters were inhibited, including the rates and extents of growing and shortening, the switching frequencies between growing and shortening, and the overall dynamicity. Much higher
erucin concentrations were required to reduce the microtubule
polymer mass. In addition,
erucin suppressed dynamic instability of microtubules reassembled from purified
tubulin in similar fashion. The effects of
erucin on microtubule dynamics, like those of
sulforaphane, are similar qualitatively to those of much more powerful clinically-used microtubule-targeting anticancer drugs, including
taxanes and the
vinca alkaloids. The results suggest that suppression of microtubule dynamics by
erucin and the resulting impairment of critically important microtubule-dependent cell functions such as mitosis, cell migration and microtubule-based transport may be important in its
cancer preventive activities.