Suppression of microtubule dynamic instability and turnover in MCF7 breast cancer cells by sulforaphane

Abstract

Sulforaphane (SFN), a prominent isothiocyanate present in cruciferous vegetables, is believed to be responsible along with other isothiocyanates for the cancer preventive activity of such vegetables. SFN arrests mitosis, possibly by affecting spindle microtubule function. A critical property of microtubules is their rapid and time-sensitive growth and shortening dynamics (dynamic instability), and suppression of dynamics by antimitotic anticancer drugs (e.g. taxanes and the vinca alkaloids) is central to the anticancer mechanisms of such drugs. We found that at concentrations that inhibited proliferation and mitosis of MCF7-green fluorescent protein-alpha-tubulin breast tumor cells by approximately 50% (~15 microM), SFN significantly modified microtubule organization in arrested spindles without modulating the spindle microtubule mass, in a manner similar to that of much more powerful antimitotic drugs. By using quantitative fluorescence video microscopy, we determined that at its mitotic concentration required to inhibit mitosis by 50%, SFN suppressed the dynamic instability of the interphase microtubules in these cells, strongly reducing the rate and extent of growth and shortening and decreasing microtubule turnover, without affecting the polymer mass. SFN suppressed the dynamics of purified microtubules in a similar fashion at concentrations well below those required to depolymerize microtubules, indicating that the suppression of dynamic instability by SFN in cells is due to a direct effect on the microtubules. The results indicate that SFN arrests proliferation and mitosis by stabilizing microtubules in a manner weaker than but similar to more powerful clinically used antimitotic anticancer drugs and strongly support the hypothesis that inhibition of mitosis by microtubule stabilization is important for SFN's chemopreventive activity.

Phytochemicals of Brassicaceae in plant protection and human health – Influences of climate, environment and agronomic practice

“…botrytis var. italica, cultivars) with high levels in seeds and sprouts (Sivakumar et al, 2007;You et al, 2008), has been shown to have an inhibitory effect in cell system studies on tumor growth in prostate (Bhamre et al, 2009;Shankar et al, 2008), breast (Azarenko et al, 2008) and colon cancers (Ecker et al, 2008;Gamet-Payrastre et al, 2000;Plate and Gallaher, 2003).…”

Antiproliferative Mechanism of Action of the Novel Taxane Cabazitaxel as Compared with the Parent Compound Docetaxel in MCF7 Breast Cancer Cells

“…29). Fixed cells were mounted on glass slides with antifade agent Prolong Gold-DAPI (Life Technologies, Inc.) to visualize DNA and examined by fluorescence microscopy (Nikon Eclipse E800, Â40 objective).…”

“…Cells were seeded as described above for cell viability on poly-L-lysine-treated coverslips, incubated with drug 24 hours, fixed with 3.7% formaldehyde followed by cold methanol (29) and stained with mouse monoclonal a-tubulin antibody (1:1,000 DM1A) and FITC-conjugated goat anti-mouse antibody (1:1,000, Cappel MP Biochemicals). Centrosomes were stained with rabbit polyclonal anti-pericentrin antibody (1:500, AB4448; Abcam) and rhodamine-conjugated goat anti-rabbit antibody (1:500, Cappel).…”

Natural product derivative Bis(4-fluorobenzyl)trisulfide inhibits tumor growth by modification of β-tubulin at Cys 12 and suppression of microtubule dynamics

“…One major mechanism of acquired drug resistance is the overexpression of efflux pumps, i.e., the p-gp170/MDR (21,(27)(28)(29)(30)(31), and many clinically used drugs are good substrate of the drug efflux pump (21,27). To test the effect of MDR expression on the sensitivity of tumor cells to BFBTS, we used MCF7/adr and human epidermoid carcinoma cell line KBv200, where the overexpression of MDR1 is induced by exposure to low dose of vinblastine or daunorubincin (28)(29)(30)(31). The MCF7/adr and KBv200 as well as their parental lines (MCF7 and KB) were treated with different concentrations of BFBTS and paclitaxel, and the cell responses were continuously monitored in real-time for 48 hours after treatment.…”