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The nuclear membrane in multidrug resistance: microinjection of epirubicin into bladder cancer cell lines.
BJU Int. 2005 May; 95(7):1091-8.BI

Abstract

OBJECTIVE

To assess whether microinjecting epirubicin into cells showing multidrug resistance (MDR, common to many cancers, including bladder cancer, with resistance to, e.g. anthracyclines and mitomycin C) spares the nucleus, as when these drugs accumulate, distribution in MDR cells characteristically spares the nucleus, suggesting that the nuclear membrane is responsible for excluding cytotoxic drugs from MDR nuclei.

MATERIALS AND METHODS

Nuclear exclusion of drugs is an important feature of resistance in MDR cells, as many MDR-susceptible drugs have cytotoxic actions within the nucleus. Drug accumulation in 'classical' P-glycoprotein-mediated MDR cells is greatly reduced by efflux. Microinjection of epirubicin into the cytoplasm of MDR cells bypasses the P-glycoprotein efflux pump on the plasma membrane. Nuclear sparing would directly implicate the nuclear membrane in this phenomenon. Because of their fluorescence properties, which allow study by confocal microscopy and flow cytometry, anthracyclines have also been used extensively to investigate MDR. Thus sensitive (MGH-U1 and RT112) and MDR (MGH-U1R and MGH-U1-MMC) bladder cancer cell lines were used. Adherent cells from each cell line were individually microinjected with epirubicin (0.5 mg/mL) and a 77 kDa fluorescein isothiocyanate (FITC)-dextran (0.5 mg/mL). The pattern of nuclear epirubicin uptake in injected cells was then evaluated by confocal microscopy. The 77 kDa FITC-dextran allowed easier identification of injected cells and was also excluded from their nuclei.

RESULTS

Sensitive bladder cancer cell lines all showed a nuclear accumulation pattern of epirubicin, consistent with their normal uptake after exposure to epirubicin. The MDR cell lines showed the characteristic nuclear-sparing pattern of epirubicin uptake, similar to the normal uptake pattern after epirubicin exposure. The 77 kDa FITC-dextran showed clearly which cells had been microinjected, and was excluded from the nuclei of all injected cells. Cell viability was confirmed by acridine-orange staining after initial visualization of injected cells.

CONCLUSION

The nuclear membrane is responsible for the nuclear exclusion of epirubicin in MDR cells. Further work is necessary to determine the mechanisms involved.

Authors+Show Affiliations

Department of Urology, Southampton University Hospitals NHS Trust, Southampton, UK. JonFeath@aol.comNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15839939

Citation

Featherstone, Jonathan M., et al. "The Nuclear Membrane in Multidrug Resistance: Microinjection of Epirubicin Into Bladder Cancer Cell Lines." BJU International, vol. 95, no. 7, 2005, pp. 1091-8.
Featherstone JM, Speers AG, Lwaleed BA, et al. The nuclear membrane in multidrug resistance: microinjection of epirubicin into bladder cancer cell lines. BJU Int. 2005;95(7):1091-8.
Featherstone, J. M., Speers, A. G., Lwaleed, B. A., Hayes, M. C., Cooper, A. J., & Birch, B. R. (2005). The nuclear membrane in multidrug resistance: microinjection of epirubicin into bladder cancer cell lines. BJU International, 95(7), 1091-8.
Featherstone JM, et al. The Nuclear Membrane in Multidrug Resistance: Microinjection of Epirubicin Into Bladder Cancer Cell Lines. BJU Int. 2005;95(7):1091-8. PubMed PMID: 15839939.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The nuclear membrane in multidrug resistance: microinjection of epirubicin into bladder cancer cell lines. AU - Featherstone,Jonathan M, AU - Speers,Alan G, AU - Lwaleed,Bashir A, AU - Hayes,Matthew C, AU - Cooper,Alan J, AU - Birch,Brian R, PY - 2005/4/21/pubmed PY - 2005/5/27/medline PY - 2005/4/21/entrez SP - 1091 EP - 8 JF - BJU international JO - BJU Int VL - 95 IS - 7 N2 - OBJECTIVE: To assess whether microinjecting epirubicin into cells showing multidrug resistance (MDR, common to many cancers, including bladder cancer, with resistance to, e.g. anthracyclines and mitomycin C) spares the nucleus, as when these drugs accumulate, distribution in MDR cells characteristically spares the nucleus, suggesting that the nuclear membrane is responsible for excluding cytotoxic drugs from MDR nuclei. MATERIALS AND METHODS: Nuclear exclusion of drugs is an important feature of resistance in MDR cells, as many MDR-susceptible drugs have cytotoxic actions within the nucleus. Drug accumulation in 'classical' P-glycoprotein-mediated MDR cells is greatly reduced by efflux. Microinjection of epirubicin into the cytoplasm of MDR cells bypasses the P-glycoprotein efflux pump on the plasma membrane. Nuclear sparing would directly implicate the nuclear membrane in this phenomenon. Because of their fluorescence properties, which allow study by confocal microscopy and flow cytometry, anthracyclines have also been used extensively to investigate MDR. Thus sensitive (MGH-U1 and RT112) and MDR (MGH-U1R and MGH-U1-MMC) bladder cancer cell lines were used. Adherent cells from each cell line were individually microinjected with epirubicin (0.5 mg/mL) and a 77 kDa fluorescein isothiocyanate (FITC)-dextran (0.5 mg/mL). The pattern of nuclear epirubicin uptake in injected cells was then evaluated by confocal microscopy. The 77 kDa FITC-dextran allowed easier identification of injected cells and was also excluded from their nuclei. RESULTS: Sensitive bladder cancer cell lines all showed a nuclear accumulation pattern of epirubicin, consistent with their normal uptake after exposure to epirubicin. The MDR cell lines showed the characteristic nuclear-sparing pattern of epirubicin uptake, similar to the normal uptake pattern after epirubicin exposure. The 77 kDa FITC-dextran showed clearly which cells had been microinjected, and was excluded from the nuclei of all injected cells. Cell viability was confirmed by acridine-orange staining after initial visualization of injected cells. CONCLUSION: The nuclear membrane is responsible for the nuclear exclusion of epirubicin in MDR cells. Further work is necessary to determine the mechanisms involved. SN - 1464-4096 UR - https://www.unboundmedicine.com/medline/citation/15839939/The_nuclear_membrane_in_multidrug_resistance:_microinjection_of_epirubicin_into_bladder_cancer_cell_lines_ L2 - https://doi.org/10.1111/j.1464-410X.2005.05473.x DB - PRIME DP - Unbound Medicine ER -