Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
Biochim Biophys Acta. 2011 Jan;1813(1):159-67. doi: 10.1016/j.bbamcr.2010.09.018. Epub 2010 Oct 12.

Role of hypoxia and EGF on expression, activity, localization and phosphorylation of carbonic anhydrase IX in MDA-MB-231 breast cancer cells.

Author information

  • 1Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610-0267, USA.

Abstract

Carbonic anhydrase IX (CAIX) is a zinc metalloenzyme that catalyzes the reversible hydration of CO(2). CAIX is overexpressed in many types of cancer, including breast cancer, but is most frequently absent in corresponding normal tissues. CAIX expression is strongly induced by hypoxia and is significantly associated with tumor grade and poor survival. Herein, we show that hypoxia induces a significant increase in CAIX protein in MDA-MB-231 breast cancer cells. Using a unique mass spectrophotometric assay, we demonstrate that CAIX activity in plasma membranes isolated from MDA-MB-231 is correlated with CAIX content. We also show that CAIX exists predominantly as a dimeric, high-mannose N-linked glycoprotein. While there is some evidence that the dimeric form resides specifically in lipid rafts, our data do not support this hypothesis. EGF, alone, did not affect the distribution of CAIX into lipid rafts. However, acute EGF treatment in the context of hypoxia increased the amount of CAIX in lipid rafts by about 5-fold. EGF did not stimulate tyrosine phosphorylation of CAIX, although EGFR and down-stream signaling pathways were activated by EGF. Interestingly, hypoxia activated Akt independent of EGF action. Together, these data demonstrate that the active form of CAIX in the MDA-MB-231 breast cancer cell line is dimeric but that neither lipid raft localization nor phosphorylation are likely required for its dimerization or activity.

Copyright © 2010 Elsevier B.V. All rights reserved.

PMID:
20920536
[PubMed - indexed for MEDLINE]
PMCID:
PMC3014402
Free PMC Article

Images from this publication.See all images (6)Free text

Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Icon for Elsevier Science Icon for PubMed Central
    Loading ...
    Write to the Help Desk