To investigate the phenomenon of active dissociation of the vital dye, Hoechst 33342 (Ho342), from DNA (DNA clearing), a new MCF7HoeR-7 human breast carcinoma cell line was isolated from parent MCF7 cells by step-wise selection with increasing concentrations of Ho342. This cell line possesses an enhanced ability for DNA clearing. The MCF7HoeR-7 line is characterised in detail and compared with the parental MCF7 line and a typical P-glycoprotein-mediated multidrug resistant (MDR) cell line, MCF7/Adr. MCF7HoeR-7 cells have an increased population growth rate, a lower DNA content and a reduced number of chromosomes. Enhanced DNA clearing in MCF7HoeR-7 cells is associated with the high resistance of the cells to the toxic effects of Ho342 and cross-resistance to etoposide, a topoisomerase II inhibitor in clinical use. The MCF7HoeR-7 and parent MCF7 cell lines have similar expression levels of transport proteins. The results obtained confirm that DNA clearing is an atypical MDR mechanism in tumour cells.
EndicottJ.A., & LingV. (1989). The biochemistry of P-glycoprotein-mediated multidrug resistance. Annual Review of Biochemistry58, 137–171.
2.
LitmanT., DruleyT.E., SteinW.D., & BatesS.E. (2001). From MDR to MXR: new understanding of multidrug resistance systems, their properties and clinical significance. Cellular and Molecular Life Sciences58, 931–959.
3.
WieseM., & PajevaI.K. (2001). Structure activity relationships of multidrug resistance reversers. Current Medical Chemistry8, 685–715.
4.
SmithP.J., DebenhamP.G., & WatsonJ.V. (1989). A role of DNA topoisomerases in the active dissociation of DNA minor groove ligand complex. Mutation Research217, 169–172.
5.
FilatovM.V., & VarfolomeevaE.Y. (1995). Active dissociation of Hoechst 33342 from DNA in living mammalian cells. Mutation Research327, 209–215.
6.
LevinaV.V., VarfolomeevaE.Y., & FilatovM.V. (1999). “DNA clearing” from non-covalently bound agents in mammalian cells as a new mechanism of drug resistance. Membrane Cell Biology12, 883–893.
7.
NaryznyS.N., LevinaV.V., VarfolomeevaE.Y., DrobchenkoE.A., & FilatovM.V. (1999). Active dissociation of Hoechst from DNA in a living cell: who could do it?Electrophoresis20, 1033–1038.
8.
LevinaV., VarfolomeevaE., & FilatovM. (2000). A new mechanism of mammalian cell resistance to the toxic effects of DNA binding agents. ATLA28, 451–456.
9.
CowanK.H., BatistJ., TupuleA., SinhaB.K., & MyesC.E. (1986). Similar biochemical changes in human breast cancer cells and in carcinogen-induced resistance to xenobiotics. Proceedings of the National Academy of Sciences USA83, 9328–9332.
10.
WatsonJ.V., ChambersS.H., & SmithP.J. (1987). A pragmatic approach to analysis of DNA histograms with a definable G1 peak. Cytometry8, 1–8.
11.
KubiesM., SchindlerD., HoehnH., RabinovichP.S. (1985). Cell cycle kinetics by BrdU-Hoechst cytometry: alternative to the differential methaphase labelling technique. Cell and Tissue Kinetics18, 551–562.
12.
Xi-GangG., MorganW.F., & CleaverJ.E. (1986). Hoechst 33258 dye generates DNA-protein crosslinks during ultraviolet light-induced photolysis of bromodeoxyuridine in replicated and repaired DNA. Photochemistry and Photobiology44, 131–136.
13.
KrishanA., FitzC.M., & AndritschI. (1997). Drug retention, efflux, and resistance in tumor cells. Cytometry29, 279–285.
14.
LahmyS., VialletP., & SalmonJ.M. (1995). Is reduced accumulation of Hoechst 33342 in multidrug resistant cells related to P-glycoprotein activity?Cytometry19, 126–133.
15.
TurnerP.R., & DennyW.A. (1996). The mutagenetic properties of DNA minor-groove binding ligands. Mutation Research355, 141–169.
16.
ChenA.Y., YuC., GattoB., & LiuL.F. (1993). DNA minor groove-binding ligands: a different class of mammalian DNA topoisomerase I inhibitors. Proceedings of the National Academy of Sciences, USA90, 8131–8135.
17.
ZhangX., & KiechleF. (2001). Hoechst 33342-induced apoptosis is associated with decreased immunoreactive topoisomerase I and topoisomerase I-DNA complex formation. Annals of Clinical and Laboratory Science31, 187–198.
ShapiroA.B., & LingV. (1997). Extraction of Hoechst 33342 from the cytoplasmic leaflet of the plasma membrane by P-glycoprotein. European Journal of Biochemistry250, 122–129.
20.
KimM., TurnquistH., JacksonJ., SgagiasM., YanY., GongM., DeanM., SharpG., & CowanK. (2002). The multidrug resistance transporter ABCG2 (breast cancer resistance protein 1) effluxes Hoechst 33342 and is overexpressed in hematopoietic stem cells. Clinical Cancer Research8, 22–28.
21.
MurrenJ.R., DiStasioS.A., LoricoA., McKeonA., ZuhowskiE.G., EgorinM.J., SartorelliA.C., & RappaG. (2000). Phase I and pharmacokinetic study of novobiocin in combination with VP-16 in patients with refractory malignancies. Cancer Journal6, 256–265.
22.
RappaG., MurrenJ.R., JohnsonL.M., LoricoA., & SartorelliA.C. (2000). Novobiocin-induced VP-16 accumulation and MRP expression in human leukemia and ovarian carcinoma cells. Anticancer Drug Design15, 127–134.
23.
ChowK.C., MacDonaldT.L., & RossW.E. (1988). DNA binding by epipodophyllotoxins and N-acyl anthracyclines: implications for mechanism of topoisomerase II inhibition. Molecular Pharmacology34, 467–473.
