OVEREXPRESSION OF THE MTA1 GENE IN GASTROINTESTINAL CARCINOMAS - CORRELATION WITH INVASION AND METASTASIS

The mtal gene is a recently identified novel candidate metastasis asso ciated gene. The deduced amino acid sequence contains an src homology- 3 domain binding motif, a zinc finger motif and possible phosphorylati on sites, suggesting that this gene is involved in signal transduction or regulation of gene expression. The purpose of our study was to exa mine the mRNA expression levels of the MTAI, the human homologue of th e rat mtal gene in colorectal and gastric carcinomas and thus to evalu ate the relevance of the expression of this gene to human carcinoma pr ogression. The expression of MTAI mRNA in 36 colorectal and 34 gastric carcinoma samples was compared with that in corresponding normal muco sa tissues by semi-quantitative reverse-transcription polymerase chain reaction (RT-PCR) and the results were compared with clinico-patholog ic data. A relative overexpression of MTAI mRNA (tumor/normal ratio gr eater than or equal to 2) was observed in 14 of 36 (38.9%) colorectal carcinomas and 13 of 34 (38.2%) gastric carcinomas, Clinico-pathologic correlations demonstrated that in colorectal carcinomas, tumors overe xpressing MTAI mRNA exhibited a significantly deeper wall invasion and a higher rate of metastasis to lymph nodes, and tended to be at an ad vanced Dukes' stage with frequent lymphatic involvement, In gastric ca rcinomas, the tumors overexpressing MTAI mRNA showed significantly hig her rates of serosal invasion and lymph node metastasis and tended to have a higher rate of vascular involvement. Our data suggest that over expression of the MTAI gene correlates with tumor invasion and the pre sence of metastases and that a high expression of MTAI mRNA may be a p otential indicator for assessing the malignant potential of colorectal and gastric carcinomas, (C) 1997 Wiley-Liss, Inc.