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.
Laboratories of Cell Signaling and Bioorganic Chemistry, Faculty of Integrated Arts and Sciences, The University of Tokushima, Japan.
Chisato
C
Umebayashi
Natsuko
N
Yamamoto
Hiromi
H
Nakao
Yukiko
Y
Toi
Lumi
L
Chikahisa-Muramatsu
Kaori
K
Kanemaru
Toshiya
T
Masuda
Yasuo
Y
Oyama
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