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Osteoblast‐conditioned media influence the expression of E‐selectin on bone‐derived vascular endothelial cells
Author(s) -
Makuch Lauren A.,
Sosnoski Donna M.,
Gay Carol V.
Publication year - 2006
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.20861
Subject(s) - osteoblast , bone marrow , chemistry , microbiology and biotechnology , endothelial stem cell , biology , immunology , in vitro , biochemistry
Breast cancer cells frequently metastasize to the ends of long bones, ribs and vertebrae, structures which contain a rich microvasculature that is closely juxtaposed to metabolically active trabecular bone surfaces. This study focuses on the effects of osteoblast secretions on the surface presentation of adhesive proteins on skeletal vascular endothelial cells. Vascular endothelial cells were isolated from trabecular bone regions of the long bones of 7‐week‐old Swiss Webster mice and also from the central marrow cavity where trabecular bone is absent. Both types of endothelial cells were placed in culture for 7 days, then exposed 24 h to conditioned media from MC3T3‐E1 osteoblasts. Conditioned medium (CM) from two different stages of osteoblast development were tested: (1) from immature MC3T3‐E1 cells cultured for 5–7 days and (2) from mature MC3T3‐E1 cells cultured for 28–30 days. The immature osteoblasts were in a stage of rapid proliferation; the mature osteoblasts formed a matrix that mineralized. Following exposure to the conditioned media, the vascular cells were exposed to anti‐P‐selectin, anti‐E‐selectin, anti‐ICAM‐1, and anti‐VCAM‐1 to detect the corresponding adhesive proteins on their surfaces. Breast cancer cells are known to bind to these adhesive proteins. Of the four proteins evaluated, E‐selectin was consistently found on more cell surfaces (∼30%) of bone‐derived vascular endothelial cells (BVECs) when exposed to the immature CM whereas vascular endothelial cells from marrow (MVECs) did not show this response to either immature CM or mature CM. These studies suggest that the BVEC blood vessels near immature bone cells express more surface adhesive protein that could enhance entrapment and extravasation of breast cancer cells. Once cancer cells have undergone extravasation into marrow adjacent to bone, they could be readily attracted to nearby bone surfaces. J. Cell. Biochem. 98: 1221–1229, 2006. © 2006 Wiley‐Liss, Inc.