Glioblastoma (GBM) is the most malignant brain tumor that accounts for approximately 37% of gliomas and progresses rapidly to invasive, with a 5-year survival rate of 6.9% and an average survival time of 12 months. Detection of transcripts and proteins of human cytomegalovirus (HCMV) in GBM patients suggests a potential involvement of HCMV infection in GBM. We previously reported that HCMV infection in fibroblasts induces the elevation of the expression levels of host chemokines and chemokine receptors, e.g. IL-8, MCP-1, I-TAC, IL-8R1, and CCR2. Although these proinflammatory chemokines and their receptors are known to be involved in the pathogenesis of GBM, it remains to be proved that they are upregulated in GBM with HCMV infection. Hence, we examined the effects of HCMV infection on chemokine and chemokine receptor expression in GBM cell lines.
Two GBM cell lines, T98G and A172, and an astrocytoma cell line, U373-MG, were infected with HCMV Towne and clinical strain, 91S. Thirteen kinds of chemokine and eleven kinds of cytokine were screened in the culture supernatant of the infected cells by using LEGENDplex immunoassay (BioLegends). The assay revealed that MCP-1 and IL-8 were found to be elevated with infection of both or either Towne or 91S. Real-time RT-PCR analysis demonstrated that the expression of MCP-1 receptors, CCR2A and CCR2B, was also upregulated with unchanged expression of IL-8 receptors, CXCR1 and CXCR2. Finally, we addressed whether HCMV infection can change the expression level of chemokines and chemokine receptors in the glioma stem-like cells (GSLCs) that were induced from the three cell lines by culture in the stem cell medium, and observed that HCMV-infected GSLCs also exhibited increased expression of IL-8, MCP-1, CCR2A, and CCR2B.
These results suggest that HCMV may play some roles in the pathogenesis of GBM and its stem cell generation via chemokine signal pathways, particularly MCP-1/CCR2 pathway.