EXPRESSION OF A RECEPTOR PROTEIN-TYROSINE-PHOSPHATASE IN HUMAN GLIAL TUMORS

We have analyzed expression of a receptor protein tyrosine phosphatase (RPTP zeta/beta) in tissue samples from 23 human gliomas. Using the r everse transcription-polymerase chain reaction (RT-PCR) technique, we assayed for the presence or absence of mRNA transcripts encoding the i ntact receptor and 2 alternatively spliced forms of RPTP zeta/beta. Tr anscripts encoding the intact and truncated receptors were expressed i n all of the lower grade gliomas (WHO grade 1-3) analyzed, but not in 55% of the grade 4 glioblastomas multi-forme (GEM). However, this subs et of GBMs did express an alternatively spliced secreted form comprise d of only the RPTP zeta/beta extracellular domain. Our data suggests t here may be a correlation between the loss of transcripts encoding the receptor forms of RPTP zeta/beta and progression from low to high gra de gliomas. This work provides additional evidence for the importance of phosphatase isoform expression in human tumors.