Correlation of thrombospondin-1 and transforming growth factor-beta expression with malignancy of glioma.
The expression of thrombospondin-1 (TSP-1) and its role in gliomas have not been well examined. In the present study TSP-1 expression in a panel of malignant glioma cell lines and the expression of TSP-1 and transforming growth factor (TGF-beta) proteins in low-grade and malignant glioma tissues were investigated. Reverse transcription-polymerase chain reaction analysis showed that nine of nine malignant glioma cell lines expressed TSP-1 mRNA, and seven of nine glioma lines expressed TSP-2 mRNA. Production and secretion of TSP-1 were examined in the T98G glioblastoma cell line by western blot analysis. Total TSP-1 protein content in the supernatant was 10 times higher than that in the cell lysate. Secretion of TSP-1 was examined in these glioma cell lines by western blot analysis. All glioma lines secreted significant levels of TSP-1. Bioassay showed that all tumor lines had the capacity to activate latent TGF-beta. Localization of TSP-1, TGF-beta1, -beta2, and -beta3 was examined immunohistochemically in surgically resected glioma tissues, including 11 glioblastomas, six anaplastic astrocytomas, and eight astrocytomas. Most glioblastomas expressed high levels of both TSP-1 and TGF-beta. Anaplastic astrocytomas expressed moderate levels of TSP-1 and TGF-beta. Most malignant gliomas expressed various levels of TGF-beta1, -beta2, and -beta3. The expression of both proteins, however, was weak in low-grade gliomas. Normal brain tissues around the tumors were negatively or very weakly positively stained for TSP-1 and TGF-beta. These results indicate that most malignant glioma cells express TSP-1 in vitro and in vivo, and the expression of TSP-1 and TGF-beta in vivo correlates with the histologic malignancy of glioma. Overexpression of both TSP-1 and TGF-beta may increase the biologic malignancy of malignant gliomas, through generating the active form of TGF-beta in tumor tissues.
Kawataki
T
T
Department of Neurosurgery, Yamanashi Medical University, Japan.
Naganuma
H
H
Sasaki
A
A
Yoshikawa
H
H
Tasaka
K
K
Nukui
H
H
D001254:Astrocytoma / Q000378:metabolism / Q000473:pathology; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism*; D003937:Diagnosis, Differential; D005909:Glioblastoma / Q000378:metabolism / Q000473:pathology; D005910:Glioma / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D019700:Thrombospondin 1 / Q000235:genetics* / Q000378:metabolism*; D019699:Thrombospondins / Q000235:genetics / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000473:pathology; D000099262:Thrombospondin 2
D014408:Biomarkers, Tumor; D012333:RNA, Messenger; D019700:Thrombospondin 1; D019699:Thrombospondins; D016212:Transforming Growth Factor beta; D000099262:Thrombospondin 2