TY - JOUR T1 - Antiproliferative and Pro-apoptotic Effects of <em>Uncaria tomentosa</em> in Human Medullary Thyroid Carcinoma Cells JF - Anticancer Research JO - Anticancer Res SP - 4519 LP - 4528 VL - 29 IS - 11 AU - BEATE RINNER AU - ZENG XIA LI AU - HELGA HAAS AU - VERONIKA SIEGL AU - SONJA STURM AU - HERMANN STUPPNER AU - ROSWITHA PFRAGNER Y1 - 2009/11/01 UR - http://ar.iiarjournals.org/content/29/11/4519.abstract N2 - Medullary thyroid carcinoma (MTC), a rare calcitonin-producing tumor, is derived from parafollicular C-cells of the thyroid and is characterized by constitutive Bcl-2 overexpression. The tumor is relatively insensitive to radiation therapy as well as conventional chemotherapy. To date, the only curative treatment is the early and complete surgical removal of all neoplastic tissue. In this study, the antiproliferative and pro-apoptotic effects of fractions obtained from Uncaria tomentosa (Willd.) DC, commonly known as uña de gato or cat's claw were investigated. Cell growth of MTC cells as well as enzymatic activity of mitochondrial dehydrogenase was markedly inhibited after treatment with different fractions of the plant. Furthermore, there was an increase in the expressions of caspase-3 and -7 and poly(ADP-ribose) polymerase (PARP) fraction, while bcl-2 overexpression remained constant. In particular, the alkaloids isopterpodine and pteropodine of U. tomentosa exhibited a significant pro-apoptotic effect on MTC cells, whereas the alkaloid-poor fraction inhibited cell proliferation but did not show any pro-apoptotic effects. These promising results indicate the growth-restraining and apoptotic potential of plant extracts against neuroendocrine tumors, which may add to existing therapies for cancer. ER -