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Tumor Microenvironment |
1 Surgical Research Laboratory, Department of Surgery, University of California at San Francisco, San Francisco, California; 2 Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California; and 3 Department of Developmental and Molecular Biology, and Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, New York
Requests for reprints: Nancy Boudreau, Surgical Research Laboratory, Department of Surgery, University of California at San Francisco, Box 1302, San Francisco, CA 94143. Phone: 415-206-6951; Fax: 415-206-6997; E-mail: nancyjb{at}itsa.ucsf.edu.
Key Words: angiogenesis breast tumor polarity
Recruiting a new blood supply is a rate-limiting step in tumor progression. In a three-dimensional model of breast carcinogenesis, disorganized, proliferative transformed breast epithelial cells express significantly higher expression of angiogenic genes compared with their polarized, growth-arrested nonmalignant counterparts. Elevated vascular endothelial growth factor (VEGF) secretion by malignant cells enhanced recruitment of endothelial cells (EC) in heterotypic cocultures. Significantly, phenotypic reversion of malignant cells via reexpression of HoxD10, which is lost in malignant progression, significantly attenuated VEGF expression in a hypoxia-inducible factor 1
–independent fashion and reduced EC migration. This was due primarily to restoring polarity: forced proliferation of polarized, nonmalignant cells did not induce VEGF expression and EC recruitment, whereas disrupting the architecture of growth-arrested, reverted cells did. These data show that disrupting cytostructure activates the angiogenic switch even in the absence of proliferation and/or hypoxia and restoring organization of malignant clusters reduces VEGF expression and EC activation to levels found in quiescent nonmalignant epithelium. These data confirm the importance of tissue architecture and polarity in malignant progression. [Cancer Res 2009;69(16):6721–9]
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