|Questions About Lectins|
Mistletoe Lectin As Cancer Therapy
Lectins isolated from Korean mistletoe (Viscum album coloratum) induce apoptosis in tumor cells.
Cancer Lett 1999 Feb 8;136(1):33-40
Yoon TJ, Yoo YC, Kang TB, Shimazaki K, Song SK, Lee KH, Kim SH, Park CH, Azuma I, Kim JB.
Cytotoxic lectins (KML-C) were isolated from an extract of Korean mistletoe [Viscum album C.] and the chemical and biological properties of KML-C were examined, partly by comparing them with a lectin (EML-1) from European mistletoe[Viscum album L. (loranthaceae)]. The hemagglutinating activity of KML-C was inhibited by N-acetyl-D-galactosamine and D-galactose. The isolated lectins showed strong cytotoxicity against various human and murine tumor cells. Tumor cells treated with KML-C exhibited typical patterns of apoptotic cell death, such as apparent morphological changes and DNA fragmentation, and its apoptosis-inducing activity was blocked by addition of Zn2+, an inhibitor of Ca2+/Mg2+ -dependent endonucleases, in a dose-dependent manner. These results suggest that KML-C is a novel lectin related to the cytotoxicity of Korean mistletoe, and that its cytotoxic activity against tumor cells is due to apoptosis mediated by Ca2+/Mg2+ -dependent endonucleases.
Misteltoe is a traditional plant medicine for cancer treatment, widely used in Europe. Recently, studies have determined that the presumed anti-cancer component in mistletoe may in fact be the powerful lectin contained in the plant. This study is important as it help elaborate the mechanism by which mistletoe lectin may be an important anti-cancer drug: The study indicates that programmed cell death (apoptosis) is activated by the ability of the lectin to disrupt the action of enzymes involved with the transport of calcium and magnesium into the cell's nucleus.