Synergistic enhancement of resistance to cisplatin in human bladder cancer cells by overexpression of mutant-type p53 and Bcl-2

J Urol. 1999 Dec;162(6):2176-81. doi: 10.1016/s0022-5347(05)68155-4.

Abstract

Purpose: The objective of this study was to characterize the effect of mutant-type p53 and Bcl-2 expression on the sensitivity to cisplatin in a human bladder cancer cell line both in vitro and in vivo.

Materials and methods: We transfected mutant-type p53 cDNA, Bcl-2 cDNA, or both cDNAs into KoTCC-1, a human bladder cancer cell line that does not express mutant-type p53 or Bcl-2 protein. The effects of the overexpression of mutant-type p53, Bcl-2, or both on the sensitivity to cisplatin and the apoptotic features in vitro were evaluated by the MTT assay, staining with Hoechst 33258 and a DNA fragmentation assay. We then examined the in vivo effects of cisplatin treatment on the transfectants by subcutaneous and intraperitoneal tumor cell injection models in athymic nude mice.

Results: The introduction of mutant-type p53 or Bcl-2 conferred resistance to cisplatin on KoTCC-1 cells through the inhibition of apoptosis. This phenotype was more remarkable in the cell line transfected with both mutant-type p53 and Bcl-2 than in the cell lines transfected with either mutant-type p53 or Bcl-2 alone. Furthermore, the KoTCC-1 cells transfected with both mutant-type p53 and Bcl-2 exhibited significantly higher resistance to cisplatin treatment than cells transfected with mutant-type p53 or Bcl-2 alone in experimental models in vivo.

Conclusions: These findings suggest that the overexpression of both mutant-type p53 and Bcl-2 in bladder cancer cells synergistically interferes with the therapeutic effect of cisplatin through the inhibition of the apoptotic pathway.

MeSH terms

  • Animals
  • Antineoplastic Agents / therapeutic use*
  • Cisplatin / therapeutic use*
  • Drug Resistance, Neoplasm
  • Gene Expression Regulation, Neoplastic*
  • Genes, bcl-2 / genetics*
  • Genes, p53 / genetics*
  • Humans
  • Mice
  • Mice, Nude
  • Mutation*
  • Transfection
  • Tumor Cells, Cultured
  • Urinary Bladder Neoplasms / drug therapy*
  • Urinary Bladder Neoplasms / genetics*

Substances

  • Antineoplastic Agents
  • Cisplatin