Characterization of a human bladder cancer cell line selected for resistance to BMY 25067, a novel analogue of mitomycin C

Shivendra V. Singh, Bing H. Xu, Vicram Gupta, Erling O. Emerson, Howard A. Zaren, Jitesh P. Jani

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

This study describes characteristics of a human bladder cancer cell line, SCaBER/R, selected for resistance to a mitomycin C (MMC) analogue BMY 25067. The SCaBER/R cell line was isolated by repeated 24 h exposures of the parental cells to 0.09 μM BMY 25067 (IC90, 24 h drug exposure) over a period of about 180 days. Approximately 2.2-fold higher concentration of BMY 25067 was required to kill 50% of the SCaBER/R cell line compared with parental cells (P < 0.001). The IC20 and IC90 values for BMY 25067 were also significantly higher in the SCaBER/R cell line than in SCaBER. Unlike most MMC resistant cell lines, the SCaBER/R cell line displayed a marked cross-resistance to 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and lacked cross-resistance to cisplatin, doxorubicin or VP-16. The SCaBER/R cell line also displayed a marked cross-resistance to the parent drug (MMC) and BMY 25282, another analogue of MMC. NADPH cytochrome P450 reductase activity, an enzyme implicated in bio-reductive activation of MMC, did not differ significantly in these cells. DT-diaphorase activity, another MMC activation enzyme, was significantly lower in the SCaBER/R cell line when compared to the SCaBER cells. These results suggest that relatively lower sensitivity of SCaBER/R cell line to MMC and BMY 25067 may result from impaired drug activation. Cellular levels of glutathione (GSH) and GSH-transferase (GST), which have been suggested to affect the cytotoxicity of MMC, were comparable in SCaBER and SCaBER/R cell lines. BMY 25067 induced DNA interstrand cross-links (DNA-ISC) could not be detected in either of the cell lines even at drug concentrations which produced a significant cell kill. These findings suggest that (a) cellular resistance to BMY 25067 in the SCaBER/R cell line may be due to impaired drug activation, and (b) the nature of the cytotoxic lesions produced by BMY 25067 may be different from that of MMC.

Original languageEnglish (US)
Pages (from-to)49-56
Number of pages8
JournalCancer Letters
Volume95
Issue number1-2
DOIs
Publication statusPublished - Aug 16 1995

    Fingerprint

Keywords

  • BMY 25067
  • Bladder cancer
  • Mitomycin C
  • Resistance

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

Cite this