Viruses and human brain tumors: cytomegalovirus enters the fray

Abstract

Medulloblastoma is the most common malignant brain tumor in children. Overall survival rates have improved in recent years as a result of risk-stratified treatment regimens. However, medulloblastoma remains associated with substantial mortality, and survivors often experience debilitating neurological, endocrinological, and social sequelae as a result of treatment. Targeted and less toxic therapeutic strategies are therefore needed. In this issue of the JCI, Baryawno et al. report their findings that a large percentage of primary medulloblastomas and medulloblastoma cell lines are infected with human cytomegalovirus (HCMV) and suggest that targeting this virus could provide a new way to treat individuals with medulloblastoma.

Figure 1. Effect of valganciclovir and celecoxib on medulloblastoma cell lines expressing HCMV proteins as observed by Baryawno and colleagues (10).

Injection of medulloblastoma cell lines expressing HCMV proteins into the flanks of nude mice results in tumors (Control), which are reduced in size following treatment with either valganciclovir, which targets the DNA polymerase during HCMV replication, or the COX-2 inhibitor celecoxib, which prevents HCMV replication by decreasing PGE₂ levels. Treatment with a combination of celecoxib and valganciclovir causes a greater reduction in tumor size than either drug alone. LP, HCMV late protein; IE, HCMV immediate early protein.