It has been reported that
matrix metalloproteinases (
MMPs) are highly expressed in
malignant glioma cells and that this increased expression may facilitate the invasiveness of
tumor cells. The authors investigated the expression and enzymatic activity of
MMPs in rat brain during the growth of
malignant gliomas at different time intervals. C6 rat
glioma cells were unilaterally implanted into rat cerebral hemispheres. After 7 or 14 days, these brain tissues were prepared for SDS-PAGE zymography, Western blotting, immunohistochemistry, and in situ zymography. SDS-PAGE zymography and Western blotting revealed that the expression of
proMMP-2 in rat brains with C6
glioma cells was significantly higher than that in normal or the
sham-operated rat brains, and that the activated form of MMP-2 was detected only in the former but not in the latter. On immunohistochemistry, C6
glioma cells presenting invasive growth into the rat brain parenchyma and vessels demonstrated MMP-2 immunoreactivity. On in situ zymography, foci of invasive C6
glioma cells in rat brain tissue showed gelatinolytic activity. These results suggest that expression and activation of MMP-2 may be one of the crucial steps for
glioma cell invasion into the brain parenchyma in vivo.