Reversal of P-glycoprotein expressed in Escherichia coli leaky mutant by ascorbic acid.


Journal Article

It has been reported that functional expression of the multidrug resistance protein P-glycoprotein (P-gp) in E. coli is useful for screening P-gp substrates and inhibitors. In the present study, we have constructed by nitrosoguanidine and UV mutagenesis 28 leaky mutants of E. coli UT5600. These mutants are significantly susceptible to the toxic effect of known P-gp substrates and lipophilic cancer drugs. Mouse mdr1 was functionally expressed in the most permeable E. coli mutant (UTP17). Expression of P-gp in this mutant confers cross-resistance to mitomycin C, tegafur, daunorubicin, rhodamine 6G, tetraphenylphosphonium bromide and ciprofloxacin. To examine the reversal of P-gp expressed in this heterologous system, UTP17 cells expressing mouse mdr1 or lac permease as negative control were treated with various concentrations of mitomycin C with or without ascorbic acid. We found that ascorbic acid abrogated P-gp mediated multidrug resistance, suggesting that ascorbic acid might be used in combination with anticancer drugs to reduce emergence of multidrug resistance. We also demonstrated that tomato lectin antagonized the inhibitory action of ascorbic acid. This study provide a heterologous system for mdr1 expression in E. coli leaky mutant that can be used as a system for the screening of P-gp inducers and inhibitors, since it is quick and simple.

Full Text

Duke Authors

Cited Authors

  • El-Masry, EM; Abou-Donia, MB

Published Date

  • July 11, 2003

Published In

Volume / Issue

  • 73 / 8

Start / End Page

  • 981 - 991

PubMed ID

  • 12818351

Pubmed Central ID

  • 12818351

International Standard Serial Number (ISSN)

  • 0024-3205

Digital Object Identifier (DOI)

  • 10.1016/s0024-3205(03)00376-x


  • eng

Conference Location

  • Netherlands