Low-level doxorubicin resistance in benzo[a]pyrene-treated KB-3-1 cells is associated with increased LRP expression and altered subcellular drug distribution

Shuk Han Cheng*, Wing Lam, Agnes S.K. Lee, Kwok Pui Fung, Rudolf S.S. Wu, David W F FONG

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)

Abstract

The P-glycoprotein (P-gp)-negative epidermoid pharyngeal carcinoma cells KB-3-1 were grown in 0.25 mM benzo[a]pyrene (BaP) for 3 months and increased resistance to doxorubicin, but not to vinblastine, colchicine, or cisplatin, was found. Doxorubicin resistance was not altered by cyclosporin, the P-gp inhibitor. Intracellular accumulation of BaP or calcein, a substrate for P-gp and multidrug resistance protein (MRP), was not altered by inhibitors of the P-gp and MRP. The expression of cytochrome P450 (CYP) 1A1, lung-resistance- related protein (LRP), P-gp, and MRP was investigated. Overexpression of CYP1A and LRP, on the mRNA and protein levels, was found. BaP-treated KB-3-1 cells remained P-gp negative while the level of MRP was not altered. Subcellular accumulation of BaP was found to be localized in the cytoplasm and minimal in the nuclei in BaP treated cells. In contrast, even penetration of BaP to the nuclei and cytoplasm was found in untreated cells. Subcellular distribution of doxorubicin was altered following BaP treatment with localized accumulation of the cancer drug in cytoplasmic organelles but not in the nuclei. Our data suggested that LRP might play a protective role against toxic compounds. The correlation of increased expression of LRP, but not P-gp nor MRP, with decreased doxorubicin accumulation in the nuclear target suggests a pivotal role of this perinuclear transporter in the MDR phenotype of P-gp-negative cancer cells. These results also propose an alternative mechanism of cancer drug resistance emergence, namely, induction of LRP activity following treatment with BaP, an environmental toxicant and a carcinogen.

Original languageEnglish
Pages (from-to)134-142
Number of pages9
JournalToxicology and Applied Pharmacology
Volume164
Issue number2
DOIs
Publication statusPublished - 2000

Scopus Subject Areas

  • Toxicology
  • Pharmacology

User-Defined Keywords

  • Benzo[a]pyrene
  • Doxorubicin
  • Lung-resistance-related protein
  • Subcellular distribution

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