Study identifies RNA surveillance defect that fuels melanoma through endogenous retroviral RNA

Research Summary: Study identifies RNA surveillance defect that fuels melanoma through endogenous retroviral RNA

Study Title: Recurrent ZC3H18 mutations stabilize oncogenic endogenous retroviral RNA

Publication: Cell Reports

Corresponding author: Megan Insco, MD, PhD

Summary: Metastatic melanoma is the deadliest form of skin cancer, and patients with advanced disease urgently need new treatment options. In this study, Dana-Farber Cancer Institute’s Megan Insco, MD, PhD and colleagues examined how melanoma cells misuse RNA, the molecules that carry genetic instructions inside cells. Healthy cells normally remove harmful RNA before it can cause damage, but the researchers found that a key safeguard, called ZC3H18 (Z18), is missing or damaged in about one-third of melanomas and in many other cancers. When this safeguard fails, ancient virus-like sequences hidden in our DNA, which make up 8% of our genome, are copied into RNA and build up inside cancer cells, where they fuel tumor growth. Using zebrafish models, the authors found that these RNA molecules can directly worsen melanoma. In human melanoma cells, even partially blocking one of these RNAs was enough to kill the cancer cells, showing cancer cells are dependent on these ancient virus-like sequences

Significance: The findings reported today in Cell Reports reveal a new weakness in melanoma that may be treatable with RNA-based medicines. Beyond melanoma, the work may have broader implications for cancer biology and treatment. ERV expression in tumors has previously been linked to immune signaling and response to immunotherapy. In this study, Z18-mutant cells also showed gene-expression changes consistent with viral mimicry, raising the possibility that tumors with Z18 alterations could have distinct immune vulnerabilities. The authors suggest that the Z18-ERV RNA axis may represent both a biologically important cancer pathway and a potential therapeutic opportunity.

Overall, the findings expand the understanding of how defects in RNA degradation — not just changes in DNA or transcription — can reshape the cancer transcriptome and promote tumor formation.

Funding support: National Cancer Center, American Cancer Society, National Institute of Child Health and Human Development, National Institute of General Medical Sciences, National Cancer Institute, Ladieu Family Melanoma Research Fund, King Family Fund for Melanoma Research