[Effect of bufalin-inducing apoptosis on Bcl-2 and PKC in HL-60 cells].
Previous study revealed that bufalin can inhibit proliferation, and induce apoptosis in some human cancer cell lines. However, the mechanism of its anticancer effect has not been fully understood. The present study was designed to investigate the effects of bufalin-induced apoptosis on Bcl-2 and PKC in human leukemic HL-60 cells. The cell viability was determined by trypan blue dye exclusion. The apoptosis was detected by morphology, flow cytometry and DNA agarose gel electrophoresis. The expressions of Bcl-2 and PKC were analyzed by Western blot, and activity of PKC was assayed by [gamma-(32)P] isotope incorporation method. The results showed as follows: (1) proliferation of HL-60 cells was inhibited by bufalin and the IC(50) at 24, 48, 72 hours were (25.8 +/- 2.1), (8.0 +/- 1.2) and (2.3 +/- 0.3) nmol/L, respectively. (2) apoptosis of HL-60 cells was induced when the cells were treated with bufalin at concentration of 50 nmol/L for 24 hours. (3) compared with control, treatment with bufalin at concentration of 50 nmol/L for 6 - 24 hours resulted in downregulation of protein expression, decrease of phosphorylation, and cleavage of Bcl-2, simultaneously. (4) the activity of total PKC was unchanged when HL-60 cells were exposed to 1 - 100 nmol/L bufalin for 30 minutes, but PKCbetaII underwent translocation from cytosol to membrane. It is concluded that apoptosis induced by bufalin is associated with downregulation of protein expression, dephosphorylation, and cleavage of Bcl-2 in HL-60 cells.
Tian
Xin
X
Department of Oncology, The First Affiliated Hospital, China Medical University, Shenyang 110001, China.
Wang
Ping-Ping
PP
Liu
Yun-Peng
YP
Hou
Ke-Zuo
KZ
Jin
Bo
B
Luo
Ying
Y
Qu
Xiu-Juan
XJ
D017209:Apoptosis / Q000187:drug effects*; D002018:Bufanolides / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D018922:HL-60 Cells; D006801:Humans; D008419:Materia Medica / Q000494:pharmacology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000096:biosynthesis* / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis* / Q000235:genetics
D002018:Bufanolides; D004365:Drugs, Chinese Herbal; D008419:Materia Medica; D019253:Proto-Oncogene Proteins c-bcl-2; D011493:Protein Kinase C; C022777:bufalin