Haptoglobin gene expression in human glioblastoma cell lines

Increases in cerebrospinal fluid (CSF) levels of the acute phase protein ha ptoglobin (Hp) occur in central nervous system (CNS) disorders such as Alzh eimer's disease. To establish if Hp CSF level increases can be associated w ith Hp expression in brain, reverse transcription-polymerase chain reaction (RT-PCR) experiments were conducted to determine if the Hp mRNA transcript is expressed in human glioblastoma cells. Furthermore, Western blots and i mmunoprecipitations were performed to elucidate if Hp protein is synthesize d and secreted by human glioblastoma cells. The Hp mRNA (alpha (2)beta) tra nscript (1155 bp) was detected both in U-87MG and U-138MG cells, and was po sitively verified by nested PCR in which a part of the beta sequence (482 b p) was targeted for amplification. Despite the presence of Hp mRNA, Hp prot ein was not secreted by U-87MG cells as com pared to the hepatoma cell line , HepG2, where Hp protein (similar to 46 kDa) was detected in the media. Th e results suggest the expression of Hp protein by glioblastoma cells is pos sible since the Hp mRNA transcript exist, but whether or not Hp mRNA is con tained in a storage pool requiring a specific signal for translation or is transiently expressed remains to be uncovered in future studies. (C) 2001 E lsevier Science Ireland Ltd. All rights reserved.