Streffer J R, Schuster M, Pohl U, Belka C, Dichgans J, Bamberg M, Weller M
Department of Neurology, University of Tübingen, Germany.
Anticancer Res. 1999 Nov-Dec;19(6B):5265-9.
Radiotherapy is the single most effective therapy for malignant gliomas. Targeting the CD95 apoptotic pathway is a promising experimental approach to these neoplasms. Here, we asked whether irradiation modulates CD95-mediated apoptosis of human malignant glioma cells in vitro.
LN-18, LN-229 and T98G human malignant glioma cell lines were irradiated with dosages from 0-8 Gy and treated with CD95L (CD95 ligand). CD95 expression was assessed by flow cytometry. Caspase activity was determined by DEVD cleavage. Cytotoxic effects were assessed by crystal violet staining of cells in a 96-well plate assay. Clonogenic cell death was determined by a standard colony forming assay.
We find that (i) CD95L-induced apoptosis, but not irradiation-induced clonogenic cell death, involves caspase 3 activation and is blocked by the viral caspase inhibitor, crm-A. (ii) Irradiation does not modulate CD95 expression either in p53 wild-type or in p53 mutant glioma cell lines, and does not enhance CD95L-evoked caspase 3 activity or CD95L-induced clonogenic cell death.
We conclude that endogenous CD95/CD95L interactions are not involved in radiation-induced clonogenic cell death and that the killing cascades of CD95L and irradiation are independent in human malignant glioma cells.
放射疗法是恶性胶质瘤最有效的单一治疗方法。靶向CD95凋亡途径是针对这些肿瘤的一种有前景的实验方法。在此，我们探讨了辐射是否在体外调节人恶性胶质瘤细胞中CD95介导的凋亡。
用0 - 8 Gy的剂量照射LN - 18、LN - 229和T98G人恶性胶质瘤细胞系，并用CD95L（CD95配体）处理。通过流式细胞术评估CD95表达。通过DEVD裂解测定半胱天冬酶活性。通过96孔板细胞结晶紫染色评估细胞毒性作用。通过标准集落形成试验确定克隆源性细胞死亡。
我们发现：（i）CD95L诱导的凋亡涉及半胱天冬酶3激活，而辐射诱导的克隆源性细胞死亡不涉及，且被病毒半胱天冬酶抑制剂crm - A阻断。（ii）辐射在p53野生型或p53突变型胶质瘤细胞系中均不调节CD95表达，也不增强CD95L诱发的半胱天冬酶3活性或CD95L诱导的克隆源性细胞死亡。
我们得出结论，内源性CD95/CD95L相互作用不参与辐射诱导的克隆源性细胞死亡，且在人恶性胶质瘤细胞中，CD95L和辐射的杀伤级联是独立的。
