P-Glycoprotein is overexpressed and functional in severely heat-shocked hepatoma cells

Anna Hevér-Szabó, Melinda Pirity, Margit Szathmári, Anikó Venetianer

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Abstract

Background: Hyperthermia is used in the treatment of some human malignancies. Thermotolerance may interfere with the efficacy of hyperthermic treatment, and thermotolerant cells may also display an enhanced resistance to some anticancer drugs. We have earlier isolated stable heat-resistant rat hepatoma variants and examined whether heat resistance influenced the drug sensitivity of the cells. Materials and Methods. Heat resistant variants were isolated by ten repeated cycles of heat exposure at 45°C for 80 min. Highly multidrug-resistant variants were isolated by stepwise selection with colchicine. Results: The heat-resistant variants became moderately multidrug resistant. This resistance was further increased by stepwise selection with colchicine (highly multidrug resistant variants). The levels of P-glycoprotein were elevated both in moderately and highly drug resistant variants. Decreased retention of antitumor drugs was observed in the multidrug resistant variants, verapamil increased doxorubicin retention significantly. Estradiol was almost without effect, while tamoxifen increased the drug uptake. Amplification of the MDR gene occurred in a part of the highly multidrug resistant variants. Conclusions. Acquired stable heat resistance of cancer cells can prevent the efficacy not only of hyperthermic treatment, but also the success of chemotherapy.

Original languageEnglish
Pages (from-to)3045-3048
Number of pages4
JournalAnticancer research
Volume18
Issue number4 C
Publication statusPublished - Jul 1 1998

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Keywords

  • Heat resistance
  • Hepatoma
  • Multidrug resistance
  • P-glycoprotein
  • Stress

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

Cite this

Hevér-Szabó, A., Pirity, M., Szathmári, M., & Venetianer, A. (1998). P-Glycoprotein is overexpressed and functional in severely heat-shocked hepatoma cells. Anticancer research, 18(4 C), 3045-3048.