Abstract
Accumulating evidence suggests that multiple complex mechanisms may be involved, simultaneously or complementarily, in the emergence and development of multidrug resistance (MDR) in various cancers. Cell adhesion-mediated MDR is one such mechanism. In the present study, we initially observed increased cell adhesion to extracellular matrix proteins by the MDR human breast tumor cell line MCF-7/MX compared to its parental cells. We then used a strategy that combined antibody-based screening technique and mass spectrometry-based proteomics to identify membrane proteins that contribute to the enhanced adhesion of MCF-7/MX cells. Using MCF-7/ MX cells as immunogen, we isolated a mouse monoclonal antibody, 9C6, that preferentially reacts with MCF-7/MX cells over the parental MCF-7 cells. The molecular target of 9C6 was identified as cytokeratin 8 (CK8), which was found to be overexpressed on the cell surface of MCF-7/MX cells. We further observed that down-regulation of cell surface levels of CK8 through siRNA transfection significantly inhibited MCF-7/MX cell adhesion to fibronectin and vitronectin. In addition, anti-CK8 siRNA partially reversed the MDR phenotype of MCF-7/MX cells. Taken together, our results suggest that alterations in the expression level and cellular localization of CK8 may play a significant role in enhancing the cellular adhesion of MDR MCF-7/MX cells.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1275-1284 |
| Number of pages | 10 |
| Journal | Neoplasia |
| Volume | 10 |
| Issue number | 11 |
| DOIs | |
| State | Published - Nov 2008 |
| Externally published | Yes |
Bibliographical note
Funding Information:Abbreviations: MDR, multidrug resistance; BCRP, breast cancer resistance protein; CK8, cytokeratin 8; WT, wild type; MX, mitoxantrone; SRB, sulforhodamine B; FN, fibronectin; VN, vitronectin; HEK, human embryonic kidney; MALDI-TOF MS, Matrix-assisted laser desorption/deionization–time-of-flight mass spectrometry Address all correspondence to: Zhenping Zhu or Dongsheng Xiong, Department of Pharmacy, Institute of Hematology & Hospital of Blood Diseases, Chinese Academy of Medical Sciences, 288 Nanjing Road, Tianjin 300020, China. E-mail: zhenping.zhu@ imclone.com, [email protected] 1This research was supported by National Natural Science Foundation of China (Nos. 30572203, 30570772, 30400405), Natural Science Foundation of Tianjin (No. 05YFJZJC01200), and National High Technology Research and Development Program (the 863 Program) of the Chinese Government (No. 2002AA2Z346D). 2These authors contributed equally to the study. Received 16 July 2008; Revised 23 August 2008; Accepted 26 August 2008 Copyright © 2008 Neoplasia Press, Inc. All rights reserved 1522-8002/08/$25.00 DOI 10.1593/neo.08810
