Down-regulation of matrix Gla protein messenger RNA in human colorectal adenocarcinomas

Matrix Gla protein (MGP) is a vitamin K-dependent extracellular matrix prot ein commonly found in a variety of tissues. In this study, we describe the potential use of MGP gene expression as the tumor marker of colorectal canc er. A decrease in expression of the MGP gene was also discovered in colorec tal cancer using differential screening of cDNA libraries. The MGP expressi on in 80 human colorectal adenocarcinomas was quantified by a Northern blot analysis to better define the expression pattern of MGP in colorectal canc er. The expression of MGP mRNA was reduced in 63 of 80 (79%) colorectal ade nocarcinomas (P < 0.001) as compared to the mRNA in adjacent normal tissue, implying that a decrease in MGP expression is associated with colorectal c ancer development. The proportion of tumors with downregulated expression o f MGP was lower in Duke's A/B than Duke's C/D (34 of 47 versus 26 of 33, re spectively) tumors and was lower in moderate differentiation than poor diff erentiation (44 of 64 versus 16 of 16, respectively). However, chi (2) anal ysis does not reveal any correlation between a loss of MGP expression and t umor progression or differentiation state. In conclusion, the downregulatio n of MGP mRNA generally occurs in colorectal adenocarcinomas. Although the role of MGP in cancer development is unknown, the reduced expression of MGP may be used to distinguish the normal colorectal cells from malignant cell s. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.