Induction of CDK Inhibitors (p21WAF1 and p27Kip1) and Bak in the β-Lapachone-Induced Apoptosis of Human Prostate Cancer Cells
- 1National Research Institute of Chinese Medicine (M.-J.D.); 2Division of Urology, Department of Surgery, Taipei-Veterans General Hospital (Y.-H.C., K.-K.C.); Departments of 3Urology (Y.-H.C., K.-K.C.) and4Pharmacology (L.-K.H.), 5School of Medicine, National Yang-Ming University; and Institute of Anatomy and Cell Biology, School of Life Science, National Yang-Ming University (Y.-P.C.)
Abstract
β-Lapachone, a novel anti-neoplastic drug, induces various cancer cells to undergo apoptosis. In a previous report, we showed that β-lapachone-induced apoptosis of HL-60 cells is mediated by oxidative stress. However, in the present study, we found that β-lapachone-induced apoptosis of human prostate cancer (HPC) cells may be independent of oxidative stress. In contrast to the 10-fold β-lapachone-induced increase in H2O2production seen in HL-60 cells, only a 2- to 4-fold increase was observed in HPC cells. N-acetyl-l-cysteine (NAC), a thiol antioxidant, inhibited the apoptosis in DU145 cells after 12 h exposure to β-lapachone. Nonetheless, NAC, along with other antioxidants, failed to exert similar effect in HPC cells subjected to β-lapachone treatment for 24 h. Under this premise, we suggest that the oxidative stress may not play a crucial role in β-lapachone-mediated HPC cell apoptosis. Here we demonstrate that damage to genomic DNA is the trigger for the apoptosis of HPC cells induced by β-lapachone. According to our results, β-lapachone stimulates DNA dependent kinase expression and poly(ADP-ribose) polymerase cleavage in advance of significant morphological changes. β-Lapachone promotes the expression of cyclin-dependent kinase (cdk) inhibitors (p21WAF1 and p27Kip1), induces bak expression, and subsequently stimulates the activation of caspase-7 but not of caspase-3 or caspase-8 during the apoptosis of HPC cells. Taken together, these results suggest that the signaling pathway involving the β-lapachone-induced apoptosis of HPC cell may be by DNA damage, induction of cdk inhibitors (p21 and p27), and then subsequent stimulation of caspase-7 activation.
Footnotes
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Send reprint requests to: Yat-Pang Chau, Ph.D., Institute of Anatomy and Cell Biology, School of Life Science, National Yang-Ming University, 155, 2nd Sec., Li-Nung Street, Shih-Pai, Taipei, Taiwan 112, Republic of China. E-mail: leonchau{at}ym.edu.tw
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This work was supported by Grants NSC89-2314-B-010-029 from the National Science Council, VTY88-G5–04 from Veterans General Hospital, Tsin-Hua, Yang-Ming Research Program and awarded by Medical Research and Advancement Foundation in Memory of Dr. Chi-Shuen Tsou.
- Abbreviations:
- β-lapachone
- 3,4 dihydro-2,2-dimethyl-2H-naphtho[1,2-b] pyran-5,6-dione
- Topo
- topoisomerase
- ROS
- reactive oxygen species
- cdk
- cyclin-dependent kinase
- HPC
- human prostate cancer
- DCFH-DA
- 2′,7′-dichlorofluorescein diacetate
- HE
- hydroethidine bromide
- NAC
- N-acetyl-l-cysteine
- AO
- acridine orange
- TUNEL
- terminal deoxynucleotidyl transferase dUTP-biotin nick-end labeling
- PI
- propidium iodide
- DNA-PK
- DNA-dependent kinase
- DAB
- diaminobenzidine
- PMSF
- phenylmethylsulfonyl fluoride
- PAGE
- polyacrylamide gel electrophoresis
- PARP
- poly(ADP-ribose) polymerase
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- Received March 7, 2000.
- Accepted December 18, 2000.
- The American Society for Pharmacology and Experimental Therapeutics
