Korean J Urol.  2012 Nov;53(11):800-806.

Induction of Apoptosis of Bladder Cancer Cells by Zinc-Citrate Compound

• Hong SH
• Choi YS
• Cho HJ
• Lee JY
• Hwang TK
• Kim SW

Abstract

PURPOSE
Zinc is one of the trace minerals in the body and is known to have an anticancer effect by inducing apoptosis in prostate cancer. We aimed to investigate the antiproliferative effects of a zinc-citrate compound in bladder cancer.
MATERIALS AND METHODS
A bladder cancer cell line (MBT-2) was treated with a zinc-citrate compound at different time intervals and concentrations. Mitochondrial (m)-aconitase activity was determined by use of the aconitase assay. DNA laddering analysis was performed to investigate apoptosis of MBT-2 cells. The molecular mechanism of apoptosis was investigated by Western blot analysis of p53, p21waf1, Bcl-2, Bcl-xL, and Bax and also by caspase-3 activity analysis.
RESULTS
Treatment with the zinc-citrate compound resulted in a time- and dose-dependent decrease in cell number of MBT-2 cells. M-aconitase activity was significantly decreased. DNA laddering analysis indicated apoptosis of MBT-2 cells. The zinc-citrate compound increased the expression of p21waf1 and p53 and reduced the expression of Bcl-2 and Bcl-xL proteins but induced expression of Bax protein. The zinc-citrate compound induced apoptosis of MBT-2 cells by activation of the caspase-3 pathway.
CONCLUSIONS
We have shown that a zinc-citrate compound induces apoptotic cell death in a bladder cancer cell line, MBT-2, by caspase-3 activation through up-regulation of apoptotic proteins and down-regulation of antiapoptotic proteins.

Keyword

Apoptosis; Urinary bladder neoplasms

MeSH Terms

Aconitate Hydratase
Apoptosis
bcl-2-Associated X Protein
bcl-X Protein
Blotting, Western
Caspase 3
Cell Count
Cell Death
Cell Line
DNA
Down-Regulation
Minerals
Prostatic Neoplasms
Proteins
Up-Regulation
Urinary Bladder
Urinary Bladder Neoplasms
Zinc
Aconitate Hydratase
Caspase 3
DNA
Minerals
Proteins
Zinc
bcl-2-Associated X Protein
bcl-X Protein

Figure

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  FIG. 1 Intracellular zinc concentration. The intracellular zinc citrate concentration of MBT-2 cells. The zinc concentration became higher with time passage. However, the zinc concentration in normal saline treated group was not changed.

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  FIG. 2 Cell viablity test in 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. MBT2 cells exposed to the zinc-citrate compound showed a pattern of the decrease in a time- and dose-dependent manner.

• 

  FIG. 3 The antiproliferative effect of the zinc citrate compound with time exposure, at IC50 (0.5/10 mM).

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  FIG. 4 Mitochomdrial aconitase activity. M-aconitase activity was reduced significantly after the zinc-citrate compound treatment.

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  FIG. 5 DNA laddering analysis with Western blot. The zinc-citrate compound enhanced the expression of p21waf1 and p53, suppressed the expression of Bcl-2 and Bcl-xL proteins and stimulated the expression of Bax protein.

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  FIG. 6 Caspase-3 activity. caspase-3 activity was increased in proportion to the time exposed to the zinc-citrate compound.

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