Levels of expression of pleiotrophin and protein tyrosine phosphataseζ are decreased in human colorectal cancers

Pleiotrophin (PTN) and midkine (MK) form a distinct family of heparin binding growth factors. In a variety of human cancers, MK mRNA levels have been found to be increased as compared to adjacent non-cancerous tissues. We examined the expression of PTN, its putative receptor, namely protein tyrosine phosphatase zeta (PTP zeta, also known as RPTP beta), and a related protein, receptor-type protein tyrosine phosphatase gamma (RPTP gamma), in human colorectal cancers and the adjacent normal mucosae. PTN and PTP zeta mRNA levels were generally decreased in colorectal cancers as compared to those in adjacent normal mucosae, while the RPTP gamma level was not significantly different between them. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.