Glucosamine sulfate-induced apoptosis in chronic myelogenous leukemia K562 cells is associated with translocation of cathepsin D and downregulation of Bcl-xL.
Cathepsin D (cat D) reportedly plays an important role in certain apoptotic processes, the downstream pathways of which involve release of cytochrome c (cyt c) from mitochondria and activation of the caspase cascade. Previous studies revealed that the B-cell lymphoma 2 (Bcl-2) family members Bax or Bid play important roles in apoptotic signal transduction between cat D and mitochondria. Here, we show that glucosamine sulfate (GS) inhibits the proliferation and induces apoptosis of human chronic myelogenous leukemia K562 cells in vitro. GS interfered with the maturation of cat D. Activation of caspase-3, cleavage of poly-(ADP-ribose)-polymerase, release of cyt c, and downregulation of Bcl-xL accompanied GS-induced apoptosis, and these processes were inhibited by the cat D inhibitor pepstatin A. However, we did not detect any altered gene expression of Bcl-2, Bax, or Bid during apoptosis. Translocation of cat D from the lysosome to the cytosol was observed in GS-treated K562 cells. These findings suggest that GS-induced K562 cell apoptosis involves the translocation of cat D from the lysosome to the cytosol. Furthermore, our findings suggest that downregulation of Bcl-xL (but not Bcl-2, Bax, or Bid) connects cat D and the mitochondrial pathway, which causes the release of cyt c and activation of the caspase cascade during GS-induced apoptosis of K562 cells.
Wang
Zhe
Z
Department of Pathology, State Key Laboratory of Cancer Biology, Xijing Hospital, Fourth Military Medical University, No. 17, Changle West Road, Xi'an, 710032, PR China. zhwang@fmmu.edu.cn
Liang
Rong
R
Huang
Gao-Sheng
GS
Piao
Ying
Y
Zhang
Yong-Qing
YQ
Wang
Ai-Qin
AQ
Dong
Bao-Xia
BX
Feng
Ji-Liang
JL
Yang
Guo-Rong
GR
Guo
Ying
Y
D017209:Apoptosis / Q000187:drug effects*; D051023:BH3 Interacting Domain Death Agonist Protein / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002402:Cathepsin D / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D005944:Glucosamine / Q000494:pharmacology*; D006801:Humans; D020014:K562 Cells; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000378:metabolism; D008954:Models, Biological; D021381:Protein Transport / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D051020:bcl-X Protein / Q000378:metabolism*
C494811:BCL2L1 protein, human; D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; D053148:Caspase 3; D002402:Cathepsin D; D005944:Glucosamine