Mitochondria P-glycoprotein confers paclitaxel resistance on ovarian cancer cells
Authors Guo W, Dong W, Li M, Shen Y
Received 4 November 2018
Accepted for publication 27 February 2019
Published 17 May 2019 Volume 2019:12 Pages 3881—3891
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Amy Norman
Peer reviewer comments 3
Editor who approved publication: Dr Federico Perche
Weina Guo,* Weihong Dong,* Min Li, Yi Shen
Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
*These authors contributed equally to this work
Background: Subcellular expression of P-glycoprotein (P-gp) may play an essential role in multidrug resistance (MDR) in many cancers. However, the mitochondria expression and functional activity of P-gp in ovarian cancer are still unclear. In this study, we isolated mitochondria from A2780 cell line and its paclitaxel-resistant subline A2780T and investigated the expression and function of mitochondria P-gp.
Methods: Immunocytochemistry was used to evaluate P-gp expression and subcellular localization in cancer cells. Immunofluorescence and laser confocal microscopy were used to detect the co-localization of P-gp and mitochondria both in ovarian cancer tissues and in cell lines. Western blotting (WB), transmission electron microscopy and JC-1 kit were used to evaluate the purity, integrity and activity of the isolated mitochondria. P-gp expression in the whole cell and the isolated mitochondria was evaluated by WB. Flow cytometry was used to evaluate the efflux function of mitochondria P-gp.
Results: P-gp expression was detected at the membrane, cytoplasm and nuclei of the A2780T cells, but not in the A2780 cells. Co-localization of P-gp and mitochondria was observed in the A2780T cell line and ovarian cancer tissues, but not in A2780 cells. The purity, integration and activity of the isolated mitochondria are high. P-gp was highly expressed in the A2780T cells and the isolated mitochondria, but was not found in A2780 cells. Rho123 efflux rate was significantly increased in isolated A2780T mitochondria compared to those in A2780 (43.2% vs 9.6%), but it was partly reversed by cyclosporin A (CsA, a P-gp inhibitor).
Conclusion: P-gp is highly expressed in mitochondria of taxol-resistant ovarian cancer cells and ovarian cancer tissues and mediates the drug efflux, which probably protect cancer cells from chemotherapy.
Keywords: ovarian carcinoma, mitochondria, P-glycoprotein, multidrug resistance
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