Impairment of stromelysin-1 transcriptional activity by promoter mutations in high microsatellite instability colorectal tumors.
Colorectal tumorigenesis is characterized by the sequential inactivation of a series of tumor suppressor genes (microsatellite-stable tumors) and genetic or epigenetic alterations in mismatch repair genes in nonpoliposic hereditary tumours and 13% to 15% of sporadic colorectal cancer [high microsatellite instability (MSI-H) tumors]. We hypothesized a molecular mechanism for MSI-H colorectal tumors related to matrix metalloproteinase 3 (MMP-3) promoter mutations, down-regulation of MMP-3 expression, and impairment of MMP-9 activation. We have now analyzed the 2.2-kb full MMP-3 promoter to assess the mutation distribution. The mutations found are restricted to the polymorphic region that includes the zinc-binding protein (ZBP-89) binding element. To show that these alterations were the cause of the low expression of this gene, we have generated three constructs with different MMP-3 promoters (wild type and two mutants) and we have expressed them in SW480 human colorectal cells. The basal transcriptional activity of wild-type MMP-3 promoter was much higher than the mutants activity. In addition, 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced transcriptional activity of wild-type MMP-3 promoter was 10-fold higher than the mutants activity. Dexamethasone inhibited the basal transcriptional activity of wild-type MMP-3 promoter and of the two mutants found in the MSI-H subgroup of colorectal tumors. Significantly, dexamethasone almost completely blunted the TPA-induced effect on wild-type MMP-3 promoter transcriptional activity and on the mutants, even below their basal activity. Our data show that mutations found in the polymorphic region of the MMP-3 promoter from MSI-H colorectal tumors impair its basal and induced transcriptional activity, which may contribute to their better clinical outcome.
Morán
Alberto
A
Departamento de Bioquímica y Biología Molecular II, Facultad de Farmacia, Universidad Complutense, Madrid, Spain.
Iniesta
Pilar
P
de Juan
Carmen
C
García-Aranda
Cristina
C
Díaz-López
Antonio
A
Benito
Manuel
M
D001483:Base Sequence; D015179:Colorectal Neoplasms / Q000201:enzymology* / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics; D015536:Down-Regulation; D004789:Enzyme Activation; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D018014:Gene Transfer Techniques; D006801:Humans; D019278:Matrix Metalloproteinase 3 / Q000096:biosynthesis / Q000235:genetics*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D018895:Microsatellite Repeats / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D015533:Transcriptional Activation / Q000235:genetics*
D004268:DNA-Binding Proteins; D014157:Transcription Factors; C110951:ZNF148 protein, human; D019278:Matrix Metalloproteinase 3; D020780:Matrix Metalloproteinase 9