Activation of matrix metalloproteinase‐2 in human breast cancer cells overexpressing cyclooxygenase‐1 or ‐2

Human breast cancer cell line Hs578T was stably transfected with cDNA for cyclooxygenase-1 or -2. When the cells overexpressing cyclooxygenase-1 or -2 were stimulated with concanavalin A, the processing of matrix metalloproteinase-2 was observed with the aid of gelatin zymography. This processing was not seen in mock-transfected and original cells which did not express detectable cyclooxygenase activity. Furthermore, Northern blotting showed 8-13 fold induction of membrane-type 1 matrix metalloproteinase which processed matrix metalloproteinase-2 in the cells expressing cyclooxygenases. These findings suggest that both isoforms of cyclooxygenase mediate the processing of matrix metalloproteinase-2 through induction of membrane-type I metalloproteinase in breast cancer cells.