Effect of radiation on cytokine and cytokine receptor messenger-RNA profiles in p53 wild and mutated human glioblastoma cell lines

Objective: Glioblastoma cells produce cytokines with proinflammatory or imm unosuppressive properties, or both, which, in addition to altered p53 gene expression, have been shown to be associated with glioblastoma resistance t o radiotherapy. The reported data concerning cytokines have been isolated a nd sometimes discordant. and a comprehensive profile analysis of cytokines and their corresponding receptors in irradiated glioblastomas has received limited attention. The object of this study was to test the hypothesis that radiation alone in clinically relevant doses would not significantly alter expression of endogenous cytokines and their receptors in human glioblasto ma cell lines with wild-type and mutant p53. Design and method: Culture specimens of 4 glioblastoma cell lines of differ ent p53 gene expression (U87, U118, U251, U373) were irradiated with cobalt 60 at a dose of 10 Gy. After 48 hours, radiosensitivity was defined throug h a colony formation assay, cell cycle distribution was analyzed by flow cy tometry, and cytokine and cytokine receptor messenger-RNA (mRNA) profiles w ere defined with an RNase protection assay. Different single doses of radia tion at varying time intervals after culture were applied also to wild-type p53 cell lines. Results: All cell Lines were relatively radioresistant at lower doses of I and 2 Gy. Immunosuppressive cytokine and cytokine receptor mRNA of the Th2 (IL-13R alpha, IL-4) and Th3 family (TGF-beta1, 2 and 3, TGF-beta RI and RI I) were expressed. In contrast, only 2 proinflammatory Th1 cytokine recepto r genes (IFN-gamma Ra and IFN-gammaR beta), but no significant Th1 cytokine gene expression, were detected. Even though the population examined includ ed a large fraction of reproductively dead cells, cytokine and cytokine rec eptor mRNA profiles were not altered significantly by irradiation in all ce ll lines, regardless of the p53 status. Conclusion: These results suggest that cobalt irradiation alone at clinical ly relevant doses does not significantly alter the cytokine and cytokine re ceptor profiles in human glioblastoma cell lines.