The expression of acylphosphatase is associated with the metastatic phenotype in human colorectal tumors.

We have performed differential display comparing gene expression from cell lines derived from human colorectal tumors. The cell lines were selected for study based on their ability to form metastases following injection into athymic mice. One gene which was expressed exclusively by the metastatic lines was identified as human acylphosphatase (e.c. 3.6.1.7, acylphosphate phosphohydrolase). The expression of this gene was confirmed by RT-PCR using gene-specific primers. This gene product catalyzes the hydrolysis of phosphorylated intermediates of Na+/K(+)-ATPase and of Ca(2+)-ATPases of mammalian cells. Changes in the activity of the Na+/K(+)-ATPase pump, regulated by acylphosphatase, have been previously reported in chemically-induced colonic tumors. The differential expression of this gene in the human metastatic colorectal lines suggests it may be involved in the metastatic phenotype.