Functional role of matrix metalloproteinases in ovarian tumor cell plasticity.
OBJECTIVE
We previously demonstrated that aggressive ovarian cancer cells are able to display in vitro vasculogenic mimicry, which is reflected by their ability to form vasculogenic-like networks in 3-dimensional cultures and to express vascular cell-associated markers. The goal of this study was to examine the functional role of specific matrix metalloproteinases in the formation of vasculogenic-like networks and extracellular matrix remodeling in vitro. We also investigated the clinical relevance of matrix metalloproteinase-2 and -9 and membrane type 1-matrix metalloproteinase in human ovarian cancers with evidence of tumor cell-lined vasculature.


METHODS
Ovarian cancer cells (A2780-PAR, SKOV3, and EG) were seeded onto separate 3-dimensional cultures that contained either Matrigel or type I collagen, in the absence of endothelial cells or fibroblasts. These cultures were treated with either chemically modified tetracycline-3 (general matrix metalloproteinase inhibitor), recombinant tissue inhibitor of metalloproteinase-1 or -2, or function-blocking antibodies to matrix metalloproteinase-2 or -9 or membrane type 1-matrix metalloproteinase. In addition, 78 invasive epithelial ovarian cancers were evaluated for expression of matrix metalloproteinase-2 and -9 and membrane type 1-matrix metalloproteinase and correlated with various clinical parameters.


RESULTS
The aggressive ovarian cancer cells (SKOV3 and EG) were able to form in vitro vasculogenic-like networks and contract 3-dimensional collagen I gels, whereas the poorly aggressive A2780-PAR cell line did not. Chemically modified tetracycline-3 completely blocked the network formation. Blocking antibodies to matrix metalloproteinase-2 and membrane type 1-matrix metalloproteinase inhibited the formation of the vasculogenic-like networks and collagen gel contraction, but the antibody to matrix metalloproteinase-9 had no effect on network formation and minimal effect on gel contraction. Treatment of 3-dimensional cultures with tissue inhibitor of metalloproteinase-2 retarded the network formation and only small, partially developed structures were noted that did not form network connections. Tissue inhibitor of metalloproteinase-1 had no appreciable effect on the extent or efficiency of network formation. Human invasive ovarian cancers with evidence of tumor cell-lined vasculature were significantly more likely to have strong epithelial and stromal matrix metalloproteinase-2 and -9 and membrane type 1-matrix metalloproteinase expression (all probability values were <.05).


CONCLUSIONS
Matrix metalloproteinase-2 and membrane type 1-matrix metalloproteinase appear to play a key role in the development of vasculogenic-like networks and matrix remodeling by aggressive ovarian cancer cells. Human ovarian cancers with matrix metalloproteinase overexpression are more likely to have tumor cell-lined vasculature. These results may offer new insights for consideration in ovarian cancer treatment strategies.
Sood
Anil K
AK
Department of Gynecologic Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA. asood@mdanderson.org
Fletcher
Mavis S
MS
Coffin
Jeremy E
JE
Yang
Maria
M
Seftor
Elisabeth A
EA
Gruman
Lynn M
LM
Gershenson
David M
DM
Hendrix
Mary J C
MJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D045744:Cell Line, Tumor / Q000201:enzymology; D005260:Female; D006801:Humans; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases / Q000378:metabolism*; D008875:Middle Aged; D018716:Molecular Mimicry; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D009389:Neovascularization, Pathologic; D010051:Ovarian Neoplasms / Q000201:enzymology* / Q000473:pathology
D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases; D020778:Matrix Metalloproteinase 2