Activity of novel plant extracts against medullary thyroid carcinoma cells.

BACKGROUND Medullary thyroid carcinoma (MTC) is a rare calcitonin-producing tumor, derived from the parafollicular C-cells of the thyroid. MTC is known to be relatively insensitive to conventional chemotherapy. MATERIALS AND METHODS Eight cell lines were established from MTCs; each showed an up-regulation of Bcl-2. We investigated ten agents from plants of the genera Stemona (Stemonaceae), Aglaia (Meliaceae) and Artemisia (Asteraceae) for their effects on proliferation and apoptotic rates. Extracts have been used in traditional Chinese medicine; however, no experience on their effects on medullary thyroid carcinomas has been reported so far. Growth kinetics and viability were examined using the Casy-1-Cell Counter & Analyzer and the WST-1-based cytotoxicity assay. Apoptosis was studied by DAPI staining, by measurement of caspase-3 activity and Bcl-2 expression. RESULTS A strong antiproliferative effect was recognized in each Aglaia species and with Artesunate, whereas an enhancement of apoptosis was provoked particularly by Stemona tuberosa Lour. CONCLUSION The activity of the novel plant extracts possiby offers a new approach towards successful chemotherapy of the so far chemo-resistant medullary thyroid carcinoma.