Expression of a receptor protein tyrosine phosphatase in human glial tumors.

We have analyzed expression of a receptor protein tyrosine phosphatase (RPTPzeta/beta) in tissue samples from 23 human gliomas. Using the reverse transcription-polymerase chain reaction (RT-PCR) technique, we assayed for the presence or absence of mRNA transcripts encoding the intact receptor and 2 alternatively spliced forms of RPTPzeta/beta. Transcripts encoding the intact and truncated receptors were expressed in all of the lower grade gliomas (WHO grade 1-3) analyzed, but not in 55% of the grade 4 glioblastomas multiforme (GBM). However, this subset of GBMs did express an alternatively spliced secreted form comprised of only the RPTPzeta/beta extracellular domain. Our data suggests there may be a correlation between the loss of transcripts encoding the receptor forms of RPTPzeta/beta and progression from low to high grade gliomas. This work provides additional evidence for the importance of phosphatase isoform expression in human tumors.