Down-regulation of p210(bcr/abl) by curcumin involves disrupting molecular chaperone functions of Hsp90.
OBJECTIVE
To investigate the effects of curcumin (Cur) on p210(bcr/abl) level in K562 cells, and the relationship between these effects and the molecular chaperone functions of heat shock protein 90 (Hsp90).


METHODS
Flow cytometry and Western blot were used to examine the abundance of p210(bcr/abl), Hsp90, p23, Hsp70, and p60(Hop) in K562 cells treated with Cur. Reverse transcription polymerase chain reaction (RT-PCR) was used to determine the bcr-abl mRNA level in K562 cells treated with Cur. After co-immunoprecipitation of p210(bcr/abl) and its molecular chaperones, the immunoprecipitate was then subjected to Western blot analysis with anti-Hsp90, anti-Hsp70, anti-p23, and anti- p60(Hop)mAb.


RESULTS
An exposure of K562 cells to Cur produced time-dependent down-regulation of p210(bcr/abl), the inhibition rate of p210(bcr/abl) in K562 cells determined by flow cytometry after treatment with Cur 27.2 micromol/L for 1 h, 6 h, 12 h and 24 h was 31.2%, 63.7%, 81.3% and 94.5%, respectively. In contrast, Cur had almost no influence on bcr-abl mRNA level. Treatment with Cur for 24 h reduced the association of p210(bcr/abl) with Hsp90/p23 complex, while increasing the association of p210(bcr/abl) with Hsp70/ p60(Hop) complex; however, the total protein abundance of Hsp90, p23, and p60(Hop) in K562 cells had no apparent change, while Hsp70 increased greatly.


CONCLUSIONS
Down-regulation of p210(bcr/abl) by Cur involves dissociating the binding of p210(bcr/abl) with Hsp90/p23 complex. In contrast, the association of p210(bcr/abl) with Hsp70/ p60(Hop) complex increased.
Wu
Li-Xian
LX
Institute of Clinical Pharmacology, Department of Pharmacology, Fujian Medical University, Fuzhou 350004, China.
Xu
Jian-Hua
JH
Huang
Xiu-Wang
XW
Zhang
Kun-Zhong
KZ
Wen
Cai-Xia
CX
Chen
Yuan-Zhong
YZ
D000970:Antineoplastic Agents / Q000494:pharmacology*; D003474:Curcumin / Q000494:pharmacology*; D015536:Down-Regulation; D016044:Fusion Proteins, bcr-abl / Q000096:biosynthesis* / Q000235:genetics; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D020014:K562 Cells; D012333:RNA, Messenger / Q000096:biosynthesis
D000970:Antineoplastic Agents; D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D012333:RNA, Messenger; D016044:Fusion Proteins, bcr-abl; D003474:Curcumin