Flow cytometric estimation of cytotoxic activity of rhodexin A isolated from Rhodea japonica in human leukemia K562 cells.
We have examined the cytotoxic effect of rhodexin A isolated from the extract of Rhodea japonica on human leukemia K562 cells using a flow cytometer and compared it with that of ouabain. Rhodexin A at 30 nM started to attenuate growth without affecting viability and further increases in the concentration of rhodexin A (100 nM or more) completely inhibited growth with decreasing viability. Rhodexin A at 30-100 nM increased the G(2)M population, but decreased the G(0)G(1) population, suggesting cell cycle arrest in the G(2)M phase. Rhodexin A at 100 nM increased the number of cells with hypodiploid DNA, indicating that rhodexin A induced apoptosis. The potency of rhodexin A to inhibit growth was greater than that of ouabain. The results indicate that rhodexin A exerts a potent inhibitory action on the growth of human leukemia K562 cells by inducing cell cycle arrest and apoptosis. Rhodexin A may also be a candidate for cancer treatment because there have been clinical reports of tumor regression in patients taking cardiac glycosides.
Umebayashi
Chisato
C
Laboratories of Cell Signaling and Bioorganic Chemistry, Faculty of Integrated Arts and Sciences, The University of Tokushima, Japan.
Yamamoto
Natsuko
N
Nakao
Hiromi
H
Toi
Yukiko
Y
Chikahisa-Muramatsu
Lumi
L
Kanemaru
Kaori
K
Masuda
Toshiya
T
Oyama
Yasuo
Y
D000970:Antineoplastic Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D017209:Apoptosis; D002455:Cell Division / Q000187:drug effects; D005434:Flow Cytometry; D006027:Glycosides / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D020014:K562 Cells; D007783:Lactones / Q000737:chemistry / Q000494:pharmacology*; D010042:Ouabain / Q000494:pharmacology; D010936:Plant Extracts / Q000737:chemistry; D018515:Plant Leaves
D000970:Antineoplastic Agents; D006027:Glycosides; D007783:Lactones; D010936:Plant Extracts; C482684:rhodexin A; D010042:Ouabain