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- Title
Coexpression of Integrin α<sub>v</sub>β<sub>3</sub> and Matrix Metalloproteinase-2 (MMP-2) Coincides with MMP-2 Activation: Correlation with Melanoma Progression.
- Authors
Hofmann, Uta B.; Westphal, Johan R.; Waas, Erwin T.; Becker, Jürgen C.; Ruiter, Dirk J.; van Muijen, Goos N. P.
- Abstract
SummaryTumor cell invasion and metastasis formation depend on both adhesive and proteolytic mechanisms. Previous studies have shown that expression of matrix metalloproteinase-2 and integrin αvβ3 correlate with melanoma progression. Recently, direct binding of matrix metalloproteinase-2 to αvβ3 was implicated in presenting activated matrix metalloproteinase-2 on the cell surface of invasive cells. In this study we investigated this, using the highly metastatic, αvβ3-negative melanoma cell lines MV3 and BLM, their β3-transfected αvβ3 expressing counterparts, xenografts derived from these cell lines, and fresh human cutaneous melanoma lesions comprising all stages of melanoma progression. Expression and activation status of matrix metalloproteinase-2 were studied by reverse transcription–polymerase chain reaction, immunohistochemistry, western blotting, and zymographic analysis, respectively. Matrix metalloproteinase-2 protein expression in vitro was similar in both αvβ3-negative and αvβ3-positive cell lines. Remarkable differences, however, exist in the localization of inactive and active matrix metalloproteinase-2. Soluble active matrix metalloproteinase-2 was detectable only in the conditioned medium of αvβ3-negative cell lines and undetectable in the αvβ3-positive cell lines. Conversely, active matrix metalloproteinase-2 was present exclusively on the cell surface of the αvβ3 expressing transfectants. Western blot analysis of other components that are involved in matrix metalloproteinase-2 activation showed that processing of proMT1-matrix metalloproteinase to the activated form was enhanced in β3 transfectants, whereas secretion of tissue inhibitor of metalloproteinase-2 was decreased. In vivo, the presence of functionally active matrix metalloproteinase-2 was significantly higher in xenografts derived from the αvβ3 expressing MV3 and BLM cell lines. In human cutaneous melanoma lesions, neither matrix metalloproteinase-2 nor integrin αvβ3 is detectable in melanoma in situ as determined by immunohistochemistry. In contrast, the number of matrix metalloproteinase-2-positive and αvβ3-positive tumor cells was clearly increased in primary melanomas, and melanoma metastases. Double staining experiments and confocal laser microscopy demonstrated that the percentage of cells coexpressing matrix metalloproteinase-2 and αvβ3 increased in advanced primary melanomas and melanoma metastases. In addition, zymography showed that functionally active matrix metalloproteinase-2 was frequently present in melanoma metastases. In these lesions a high proportion of matrix metalloproteinase-2- and αvβ3-double-positive melanoma cells were detectable. Our study demonstrates that the presence of activated matrix metalloproteinase-2 correlates with expression of αvβ3 in human melanoma cells both in vitro and in vivo, and also in fresh human melanoma lesions. These findings strongly suggest that co-ordinated expression of both factors may be required for melanoma cell invasion and metastasis formation.
- Subjects
XENOGRAFTS; MELANOMA
- Publication
Journal of Investigative Dermatology, 2000, Vol 115, Issue 4, p625
- ISSN
0022-202X
- Publication type
Article
- DOI
10.1046/j.1523-1747.2000.00114.x