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Nuclear immunolocalization of P-glycoprotein in multidrug-resistant cell lines showing similar mechanisms of doxorubicin distribution.
Eur J Cell Biol. 1995 Nov; 68(3):226-39.EJ

Abstract

The MDR1 gene product P-glycoprotein is a plasma membrane efflux pump which is responsible for multiple drug resistance of cancer cells. Although the ability of multidrug-resistant cells to exclude drugs from the nucleus is a distinctive and possibly the main mechanism for resistance against a number of drugs, including doxorubicin, this phenomenon is not entirely understood. In this paper, the relationship between doxorubicin subcellular distribution and P-glycoprotein activity at different cell sites has been investigated by different techniques. Cytofluorometry and confocal microscopy were used to study doxorubicin subcellular distribution in U-2 OS human osteosarcoma cells and in the multidrug-resistant variant U-2 OS/DX580. Stable levels of doxorubicin accumulation were found in the nuclei of sensitive cells, whereas the absence of detectable levels of drug in the nuclei of resistant cells could be attributed to an energy-dependent mechanism. Moreover, in resistant cells, inhibition of P-glycoprotein activity was able to induce drug accumulation in the nuclei of resistant cells and to achieve cytotoxic effects comparable to those observed in sensitive cells. Similar results were also found in isolated nuclei from U-2 OS/DX580 cells. The expression of P-glycoprotein in U-2 OS/DX580 and in two other multidrug-resistant cell lines (SW948-R-300 and LoVo-R-100) was investigated by confocal microscopy and immunoelectron microscopy, by using a panel of monoclonal antibodies directed against this protein. Higher levels of P-glycoprotein expression, not only in the plasma membrane and inside the cytoplasm, but also in the nucleus, were found in U-2 OS/DX580 and in LoVo-R-100 multidrug-resistant cells compared to their corresponding sensitive cells. SW948-R-300 cells, featuring increased amounts of MDR1 mRNA but lacking P-glycoprotein expression at the cell surface, showed a higher P-glycoprotein immunolabeling only in the nucleus and in the cytoplasm. The localization of P-glycoprotein in the nucleus of multidrug-resistant cells was confirmed also by studies on isolated nuclei and nuclear matrices, and by Western blot analysis on total cell and isolated nuclear extracts. These findings, suggesting the possible involvement of nuclear P-glycoprotein in the regulation of subcellular doxorubicin distribution in multidrug-resistant cells, open new insights on the mechanisms of P-glycoprotein-mediated resistance to anticancer drugs.

Authors+Show Affiliations

Laboratorio di Ricerca Oncologica, Istituti Ortopedici Rizzoli, Bologna, Italy.No affiliation info availableNo affiliation info availableNo affiliation info availableNo 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

8603675

Citation

Baldini, N, et al. "Nuclear Immunolocalization of P-glycoprotein in Multidrug-resistant Cell Lines Showing Similar Mechanisms of Doxorubicin Distribution." European Journal of Cell Biology, vol. 68, no. 3, 1995, pp. 226-39.
Baldini N, Scotlandi K, Serra M, et al. Nuclear immunolocalization of P-glycoprotein in multidrug-resistant cell lines showing similar mechanisms of doxorubicin distribution. Eur J Cell Biol. 1995;68(3):226-39.
Baldini, N., Scotlandi, K., Serra, M., Shikita, T., Zini, N., Ognibene, A., Santi, S., Ferracini, R., & Maraldi, N. M. (1995). Nuclear immunolocalization of P-glycoprotein in multidrug-resistant cell lines showing similar mechanisms of doxorubicin distribution. European Journal of Cell Biology, 68(3), 226-39.
Baldini N, et al. Nuclear Immunolocalization of P-glycoprotein in Multidrug-resistant Cell Lines Showing Similar Mechanisms of Doxorubicin Distribution. Eur J Cell Biol. 1995;68(3):226-39. PubMed PMID: 8603675.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Nuclear immunolocalization of P-glycoprotein in multidrug-resistant cell lines showing similar mechanisms of doxorubicin distribution. AU - Baldini,N, AU - Scotlandi,K, AU - Serra,M, AU - Shikita,T, AU - Zini,N, AU - Ognibene,A, AU - Santi,S, AU - Ferracini,R, AU - Maraldi,N M, PY - 1995/11/1/pubmed PY - 1995/11/1/medline PY - 1995/11/1/entrez SP - 226 EP - 39 JF - European journal of cell biology JO - Eur J Cell Biol VL - 68 IS - 3 N2 - The MDR1 gene product P-glycoprotein is a plasma membrane efflux pump which is responsible for multiple drug resistance of cancer cells. Although the ability of multidrug-resistant cells to exclude drugs from the nucleus is a distinctive and possibly the main mechanism for resistance against a number of drugs, including doxorubicin, this phenomenon is not entirely understood. In this paper, the relationship between doxorubicin subcellular distribution and P-glycoprotein activity at different cell sites has been investigated by different techniques. Cytofluorometry and confocal microscopy were used to study doxorubicin subcellular distribution in U-2 OS human osteosarcoma cells and in the multidrug-resistant variant U-2 OS/DX580. Stable levels of doxorubicin accumulation were found in the nuclei of sensitive cells, whereas the absence of detectable levels of drug in the nuclei of resistant cells could be attributed to an energy-dependent mechanism. Moreover, in resistant cells, inhibition of P-glycoprotein activity was able to induce drug accumulation in the nuclei of resistant cells and to achieve cytotoxic effects comparable to those observed in sensitive cells. Similar results were also found in isolated nuclei from U-2 OS/DX580 cells. The expression of P-glycoprotein in U-2 OS/DX580 and in two other multidrug-resistant cell lines (SW948-R-300 and LoVo-R-100) was investigated by confocal microscopy and immunoelectron microscopy, by using a panel of monoclonal antibodies directed against this protein. Higher levels of P-glycoprotein expression, not only in the plasma membrane and inside the cytoplasm, but also in the nucleus, were found in U-2 OS/DX580 and in LoVo-R-100 multidrug-resistant cells compared to their corresponding sensitive cells. SW948-R-300 cells, featuring increased amounts of MDR1 mRNA but lacking P-glycoprotein expression at the cell surface, showed a higher P-glycoprotein immunolabeling only in the nucleus and in the cytoplasm. The localization of P-glycoprotein in the nucleus of multidrug-resistant cells was confirmed also by studies on isolated nuclei and nuclear matrices, and by Western blot analysis on total cell and isolated nuclear extracts. These findings, suggesting the possible involvement of nuclear P-glycoprotein in the regulation of subcellular doxorubicin distribution in multidrug-resistant cells, open new insights on the mechanisms of P-glycoprotein-mediated resistance to anticancer drugs. SN - 0171-9335 UR - https://www.unboundmedicine.com/medline/citation/8603675/Nuclear_immunolocalization_of_P_glycoprotein_in_multidrug_resistant_cell_lines_showing_similar_mechanisms_of_doxorubicin_distribution_ L2 - https://antibodies.cancer.gov/detail/CPTC-RB1-1 DB - PRIME DP - Unbound Medicine ER -