The prostate-apoptosis-response-gene-4 (Par-4) protein has been identified as an effector of cell death in response to various apoptotic stimuli in prostate cancer cells. We found that overexpression of Par-4 by stable transfection inhibits cell migration and invasion in Caki cells. The expression of various matrix metalloproteinases (MMPs) has been implicated in the invasion and metastasis of cancer cells. In this study, we investigated whether ectopic expression of Par-4 modulates MMP-2

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... sion and activity in human renal carcinoma Caki cells. We found that overexpression of Par-4 markedly inhibited MMP-2 activity, but not MMP-9 activity. However, loss of the leucine zipper domain of Par-4 (Par-4 ΔLZ#1 and #2) did not inhibit MMP-2 activity. Further, knock-down of Par-4 with the corresponding siRNA resulted in increased invasion and metastasis of renal carcinoma Caki cells. Interestingly, overexpression or knock-down of Par-4 did not affect the expression levels of MMP-2 mRNA. Taken together, our findings suggest that Par-4 may inhibit MMP-2 activity through its post-transcriptional regulation in renal carcinoma Caki cells.