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Hypoxia/reoxygenation: A dynamic regulator of lysyl oxidase‐facilitated breast cancer migration
Author(s) -
Postovit LynneMarie,
Abbott Daniel E.,
Payne Stacey L.,
Wheaton William W.,
Margaryan Naira V.,
Sullivan Richard,
Jansen Matthias K.,
Csiszar Katalin,
Hendrix Mary J.C.,
Kirschmann Dawn A.
Publication year - 2007
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.21517
Subject(s) - lysyl oxidase , hypoxia (environmental) , cancer research , breast cancer , tumor hypoxia , cell migration , tumor progression , tumor microenvironment , biology , metastasis , downregulation and upregulation , cancer cell , ductal carcinoma , cancer , medicine , cell , chemistry , microbiology and biotechnology , biochemistry , radiation therapy , oxygen , gene , organic chemistry , tumor cells , extracellular matrix
Fluctuating oxygen levels characterize the microenvironment of many cancers and tumor hypoxia is associated with increased invasion and metastatic potential concomitant with a poor prognosis. Similarly, the expression of lysyl oxidase (LOX) in breast cancer facilitates tumor cell migration and is associated with estrogen receptor negative status and reduced patient survival. Here we demonstrate that hypoxia/reoxygenation drives poorly invasive breast cancer cells toward a more aggressive phenotype by up‐regulating LOX expression and catalytic activity. Specifically, hypoxia markedly increased LOX protein expression; however, catalytic activity (β‐aminopropionitrile inhibitable hydrogen peroxide production) was significantly reduced under hypoxic conditions. Moreover, poorly invasive breast cancer cells displayed a marked increase in LOX‐dependent FAK/Src activation and cell migration following hypoxia/reoxygenation, but not in response to hypoxia alone. Furthermore, LOX expression is only partially dependent on hypoxia inducible factor‐1 (HIF‐1α) in poorly invasive breast cancer cells, as hypoxia mimetics and overexpression of HIF‐1α could not up‐regulate LOX expression to the levels observed under hypoxia. Clinically, LOX expression positively correlates with tumor progression and co‐localization with hypoxic regions (defined by HIF‐1α expression) in ductal carcinoma in situ and invasive ductal carcinoma primary tumors. However, positive correlation is lost in metastatic tumors, suggesting that LOX expression is independent of a hypoxic environment at later stages of tumor progression. This work demonstrates that both hypoxia and reoxygenation are necessary for LOX catalytic activity which facilitates breast cancer cell migration through a hydrogen peroxide‐mediated mechanism; thereby illuminating a potentially novel mechanism by which poorly invasive cancer cells can obtain metastatic competency. J. Cell. Biochem. 103: 1369–1378, 2008. © 2007 Wiley‐Liss, Inc.