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The dichloromethane fraction of Stemona tuberosa Lour inhibits tumor cell growth and induces apoptosis of human medullary thyroid carcinoma cells

Authors ZengXia Li, Sonja Sturm, Hermann Stuppner, Elisabeth Schraml, Victor Aguiriano Moser, et al

Published 15 February 2008 Volume 2007:1(4) Pages 455—463

ZengXia Li1,2, Sonja Sturm3, Hermann Stuppner3, Elisabeth Schraml1, Victor Aguiriano Moser1, Veronika Siegl1, Roswitha Pfragner1

1Department of Pathophysiology and Immunology, Center of Molecular Medicine, Medical University of Graz, Graz, Austria; 2Department of Biochemistry and Molecular Biology, Shanghai Medical School, Fudan University, Shanghai, PR China; 3Institute of Pharmacy, Center of Molecular Biosciences, Leopold Franzens University of Innsbruck, Innsbruck, Austria

Abstract: Medullary thyroid carcinoma (MTC), a neuroendocrine tumor arising from the thyroid gland, is known to be poorly responsive to conventional chemotherapy. The root of Stemona tuberosa Lour, also called Bai Bu, is a commonly used traditional Chinese antitussive medicine. The present study investigated this medicinal herb for the first time with respect to its anticancer activity in human medullary thyroid carcinoma cells. Four extracts of Stemona tuberosa Lour, including the n-hexane fraction, (ST-1), dichloromethane (DCM) fraction, (ST-2), ethyl acetate (EtOAc) fraction, (ST-3), and methanol fraction, (ST-4) were examined for antiproliferative effects in two MTC cell lines. We observed that only the DCM fraction ST-2 inhibited cell growth and viability in a dose-dependent manner. Furthermore, we found that ST-2 also induced the apoptosis of MTC-SK cells. Caspase-3/7 was activated, while caspase-9 was not, implying that at least a caspase-dependent apoptotic pathway was involved in this process. In addition, the multicellular spheroids of MTC-SK were destroyed and the cell morphology was changed by ST-2. Our results show the strong apoptotic effects of the DCM fraction of Stemona tuberosa Lour on human medullary thyroid carcinomas, so suggesting a new candidate for chemotherapy of the so far chemo-resistant medullary thyroid carcinoma.

Keywords: apoptosis, chemoresistance, medullary thyroid carcinoma, plant-derived compounds, Stemona tuberosa Lour

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