Submitted to: Great Lakes Regional American Chemical Society Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 10/20/2004
Publication Date: 10/20/2004
Citation: Ellington, A.A., Berhow, M.A., Singletary, K. 2004. Soybean B-group saponins induce macroautophagy in HCT-15 colon cancer cells. Great Lakes Regional American Chemical Society Symposium, Abstract #118, p.95.
Technical Abstract: Experiments were conducted to evaluate the impact of triterpenoid saponins isolated from soybeans on suppression of colon cancer cell proliferation. The effects of a purified soybean B-group saponin extract on proliferation and programmed cell death were determined in cultures of human HCT-15 colon adenocarcinoma cells. Treatment of cells with the B-group soyasaponins at concentrations of 25-500 ppm significantly reduced viable cell numbers after 24 and 48 hours of exposure. When examined by transmission electron microscopy, soyasaponin-treated cells exhibited an approximate 4.5-fold increase in cell morphologies, including numerous autophagic vacuoles, characteristic of extensive macroautophagy, the defining attribute of Type II autophagic cell death (non-apoptotic) programmed cell death. In addition, the protein levels of microtubule associated protein light chain 3 (LC-3), a specific marker of macroautophagy, increased substantially following soyasaponin treatment. Taken together these results thus indicate that soybean B-group saponins, at physiologically relevant doses, can suppress HCT-15 colon adenocarcinoma cell proliferation, and can induce macroautophagy, the hallmark of autophagic cell death. These findings suggest that B-group soyasaponins may be another colon-cancer suppressive component of soy that warrants further examination as a potential chemopreventive phytochemical.