pgp - publications

Predict more pgp - ligand interactions now!

1. Oncol Rep. 2012 Feb 2. doi: 10.3892/or.2012.1671. [Epub ahead of print]

Mitochondrial localization of P-glycoprotein in the human breast cancer cell line
MCF-7/ADM and its functional characterization.

Shen Y, Chu Y, Yang Y, Wang Z.

Department of Gynecology and Obstetrics, Union Hospital, Tongji Medical College,
Huazhong University of Science and Technology, Wuhan 430022, P.R. China.

The current view of multidrug resisitance is that overexpression of membrane
P-glycoprotein (P-gp) is a major causative factor. However, the controversial
presence of subcellular P-gp may also participate in the drug resistance. In this
study, we sought to investigate the localization and functional characterization
of P-gp in mitochondria isolated from MCF-7 and doxorubicin-resistant MCF-7
(MCF-7/ADM) cells. Mitochondria were isolated and purified from the MCF-7 cell
line and its resistant cells MCF-7/ADM. We used electron microscopy, western blot
analysis and confocal microscopy to demonstrate the localization of P-gp in the
mitochondria of MCF-7/ADM cells. Flow cytometry was used to evaluated the efflux
function of mitochondrial P-gp in the presence or absence of the P-gp inhibitor
cyclosporine A (CsA). Mitochondria were isolated and purified successfully and
were analyzed by electron microscopy. Western blotting demonstrated the
expression of P-gp in the cell membrane and purified mitochondria from MCF-7/ADM
cells but not from sensitive MCF-7 cells. Immunofluorescence analysis using
confocal microscopy demonstrated the localization of P-gp [labeled with green
fluorescence (FITC)] to the mitochondria [labeled with red fluorescence
(Mitotracker Deep red 633)] of MCF-7/ADM cells and that was absent in MCF-7
cells. Rho123 (a mitochondrial fluorescent probe) accumulation was largely
reduced and efflux was strongly increased in the mitochondria of MCF-7/ADM cells
compared to those of MCF-7 cells (P<0.01), and these were completely reversed in
the presence of the P-gp inhibitor CsA (P<0.01). No significant changes were
observed in the mitochondria of MCF-7 cells (P>0.05). P-gp is expressed in the
mitochondria of doxorubicin-resistant MCF-7 cells and has an efflux function. It
could be involved in multidrug resistance at the subcellular site by pumping out
anticancer drugs from mitochondria to protect the function of mitochondria.

PMID: 22307172 [PubMed - as supplied by publisher]