Human astrocytomas and glioblastomas express monocyte chemoattractant protein‐1 (MCP‐1) in vivo and in vitro

Abstract

Expression of the monocyte chemoattractant protein‐I (MCP‐I) was examined in human central nervous system tumours (glioblastomas and astrocytomas) and normal human brain. Northern blot analysis demonstrated constitutive expression of MCP‐I mRNA in 6 of 12 glioblastoma cell lines. Expression could be stimulated by interleukin (IL)‐Iα and tumour necrosis factor (TNF)‐α in all cell lines tested. Immunoprecipitation demonstrated secretion of both isoforms, MCP‐Iα and ‐β, of the MCP‐I protein. Reverse‐transcription polymerase chain reaction and Northern blot analysis on tissues demonstrated MCP‐I mRNA expression in 17 of 17 glioblastomas, 3 of 6 anaplastic astrocytomas and 6 of 6 low‐grade astrocytomas, as well as in fetal brain but not in normal adult brain. In situ hybridization on 2 glioblastomas and I low‐grade astrocytoma indicates that neoplastic astrocytes and endothelial cells express MCP‐I mRNA in vivo. Moreover, tumour cyst fluids of glioblastomas and astrocytoms were able to induce monocyte chemoattraction in an in vitro assay. This chemotatic activity was specifically neutralized by anti‐MCP‐I antibodies in 9 of samples, further demonstrating the production of bioactive MCP‐I in vivo and supporting an important role for this factor in the infiltration of monocytes/macrophages into tumour tissue.