[Rabdocoetsin B, a diterpenoid isolated from Isodon coetsa, is a potential proteasome inhibitor and induced apoptosis of t(8;21) leukemia cells].
Effects of Rabdocoetsin B (Rabd-B), a diterpenoid extracted from Isodon coetsa, on t(8;21) leukemic cells was tested by CCK-8 assay and Flow cytometry. The A549 cells stably expressing pGC-E1-ZU1-GFP were treated with Rabd-B for 4 h, and the accumulation of GFP was detected by fluorescence microscope. Using Western blotting, we investigated the expression of Casp-3, PARP, S6', which is a subunit of the 19S regulatory complex of the 26S proteasome, and cellular ubiqutinated proteins. We found that Rabd-B induced growth inhibition and apoptosis of Kasumi-1 cells in a dose-dependent manner. In Kasumi-1 cells treated with 2.5 micromol/L Rabd-B for 24 h, pro-caspase-3 was processed into its active form. The substrate of Casp-3, poly ADP-ribose polymerase (PARP), was cleaved with generation of an 85 kD fragment. The increased GFP fluorescence intensity, cleavage of S6' and the accumulation of ubiquitinated proteins were found in Kasumi-1 cells treated with Rabd-B. These results suggested that Rabd-B is a potential proteasome inhibitor which induces programmed cell death of t(8;21) cells. Further study might provide evidence for employing Rabd-B in treating human t(8;21) leukemia.
Feng
Tingting
T
Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510663, China.
Pu
Jianxin
J
Hu
Zheng
Z
Liu
Dapeng
D
Sun
Handong
H
Zhou
Guangbiao
G
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D004224:Diterpenes / Q000302:isolation & purification / Q000494:pharmacology*; D006801:Humans; D037602:Isodon / Q000737:chemistry*; D015470:Leukemia, Myeloid, Acute / Q000473:pathology*; D061988:Proteasome Inhibitors; D014178:Translocation, Genetic; D014452:Ubiquitins / Q000378:metabolism
D000972:Antineoplastic Agents, Phytogenic; D004224:Diterpenes; D061988:Proteasome Inhibitors; D014452:Ubiquitins; C557752:rabdocoetsin B; C505407:CASP3 protein, human; D053148:Caspase 3