HUMAN GLIOMAS AND EPILEPTIC FOCI EXPRESS HIGH-LEVELS OF A MESSENGER-RNA RELATED TO RAT TESTICULAR SULFATED GLYCOPROTEIN-2, A PURPORTED MARKER OF CELL-DEATH

Clone pTB16 has been isolated by differential screening of a human glioma cDNA library. Northern blot analysis has shown that pTB16 expression is several times (> 11-fold) higher in gliomas than in a primitive neuroectodermal tumor. This observation was supported by in situ hybridization and extended to nine other gliomas. Expression was virtually absent in adenocarcinoma cells metastasized to brain. Malignant gliomas showed stronger hybridization than benign gliomas, while blood capillaries did not show hybridization. pTB16 mRNA was also shown to be expressed in established glioma cell lines and at high levels in epileptic foci, indicating that expression of the gene may be limited to certain cell types and that its upregulation is not merely a consequence of cellular proliferation. Nucleotide sequence analysis identified pTB16 as the human counterpart for rat testicular sulfated glycoprotein 2 (SGP-2), whose function in the reproductive system remains unknown. Although SGP-2 transcripts, and hence pTB16, were recently shown to be increased in neurodegenerative diseases such as scrapie in hamsters and Alzheimer disease in humans, our observations with brain tumors and epilepsy are suggestive of a role for pTB16 in neuropathologies in general and support the hypothesis of its involvement in tissue remodeling and cell death.