Increased levels of MMP-1, MMP-2, MMP-7, MMP-9,
MMP-13, and MMP-14 have been reported in the blood
and/or tissue samples from patients with CRC [74–78].
Several studies have found high MMP-1 expression to be a
potential prognostic factor in CRC, correlated with metastasis
or reduced overall or disease-free survival [78–80]. However,
a specific polymorphic allele of the MMP-1 promoter, asso-
ciated with enhanced transcriptional activity, was found to
significantly improve the 5-year survival rate in a study in-
cluding 503 CRC patients and 471 healthy individuals [81].
This apparent discrepancy between studies may be due to the
complex posttranscriptional regulation of MMP expression
and activity. Prognostic value of the gelatinases, MMP-2 and
MMP-9, has also been extensively studied, but the results are
contradicting. It seems like the prognostic value of these
enzymes might be dependent on whether they are produced
by the tumor cells or the stromal cells [75, 77, 82–85]. MMP-7
is frequently upregulated in CRCs, and several studies have
found the enzyme to be a potential prognostic factor,
predicting poorer patient outcome [76, 86–88]. In contrast to
what is reported for lung cancer, over-expression of MMP-12
mRNA was found to be a significant predictor of better
survival in a cohort of 54 patients with primary CRC,
reflecting that MMPs are not merely cancer-promoting en-
zymes [89]. In patients with colorectal cancer, strong immu-
nohistochemical staining for TIMP-2, TIMP-3, or TIMP-4 in
cancer cells or tumor stroma has been correlated with a favor-
able outcome though contradicting results have been reported
for TIMP-2 [75, 77, 83].