, an aggressive and largely incurable form of brain cancer. The study centers on human endogenous retroviruses (HERVs) and how their activity may shape the trajectory of GBM.){kind=link}
In an article published in Nature Cancer Gene Therapy, researchers have taken a step toward understanding the role of ancient viral elements in glioblastoma multiforme (GBM), an aggressive and largely incurable form of brain cancer. The study centers on human endogenous retroviruses (HERVs) and how their activity may shape the trajectory of GBM.
By leveraging advanced computational analysis of data from The Cancer Genome Atlas, the team established a high-resolution, locus-specific map of HERV expression in gliomas. This allowed them to examine differences in expression patterns among GBM, low-grade gliomas, and normal brain tissue.
The research identified 211 HERV loci with significantly altered expression levels in gliomas, most notably in GBM. Surprisingly, these alterations were more often characterized by downregulation rather than the upregulation commonly emphasized in earlier studies. This finding, consistent with observations in breast and colon cancers, suggests a more nuanced role for HERV activity, one that might involve gene repression rather than activation.
The study introduces a novel metric called the GH Score, derived from the expression of these 211 HERV loci. The score effectively distinguished between GBM, LGG, and normal tissue, and notably, lower GH Scores were linked to poorer survival outcomes in GBM patients. However, the same did not hold true for LGG, which the authors argue may represent a biologically distinct disease rather than an earlier stage of GBM.
A key aspect of the study is the link between dysregulated HERVs and a group of 18 genes encoding voltage-gated potassium channels. These channels are already known to influence cell behavior in glioblastoma, including proliferation, invasion, and treatment resistance. The researchers suggest that HERVs may modulate the expression of these channels, possibly affecting disease severity and response to therapy.
The findings also touch on HERVs’ potential as therapeutic targets. If downregulated HERVs can be reactivated, using agents such as demethylating drugs or histone deacetylase inhibitors, this could stimulate an antiviral immune response within the tumor, a phenomenon known as viral mimicry. While speculative, such approaches are being explored in other cancer types and could represent a novel angle in glioblastoma treatment.
The research was conducted using bulk RNA sequencing, which limits insight into the specific cell types driving the observed expression patterns. As single-cell analyses of transposable elements remain relatively unexplored, further studies will be needed to clarify which cells are contributing to HERV dysregulation.
Moreover, while the study underscores associations between HERV activity, potassium channel genes, and GBM outcomes, causal relationships remain to be established. It is unclear whether the altered expression of HERVs contributes to tumor progression or is merely a consequence of other changes in the tumor microenvironment.