Submitted to: Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 4/21/2004
Publication Date: 4/21/2004
Citation: Ellington, A.A., Berhow, M.A., Singletary, K. 2004. B-group soybean saponins induce macroautophagy and s-phase accumulation in hct-15 cells [abstract]. Experimental Biology 18(4):A127.
Technical Abstract: Experiments were conducted to determine the effects of a purified B-group soybean saponin extract on cell proliferation, cell cycle distribution and programmed cell death in cultures of human HCT-15 colon adenocarcinoma cells. Treatment of cells with the extract at doses of 25-100ppm significantly reduced viable cell numbers after 24 and 48 hours of exposure. Treatment of cells with 100ppm of saponins for 48 hours also resulted in a significant accumulation of cells in S-phase, as well as a significant 1.8-fold increase in the cyclin dependant kinase inhibitor p27KIP1/CIP1 protein expression. Evaluation of treated cells with transmission electron microscopy (TEM) revealed a 4-fold increase in cell morphologies characteristic of Type II non-apoptotic programmed cell death including numerous autophagic vacuoles. Saponin treated cells exhibited a 1.5-fold decrease in phosphorylation of p70S6K at serine 389 indicating that a reduction in mTor activity is associated with induction of macroautophagy. These results thus suggest that soybean saponins exert colon cancer suppressive effects through S-phase cell cycle arrest, along with induction of macroautophagy. Funded by the Illinois Council for Food and Agricultural Research.