Tumor virus-induced lineage survival circuit drives Merkel cell carcinogenesis

Approximately 80% of Merkel cell carcinoma (MCC) cases are caused by Merkel cell polyomavirus (MCV), driven by its T antigen oncogene. Why MCV drives MCC, a skin cancer that displays the neuroendocrine Merkel cell phenotype, remains unclear. In this issue of the JCI, Miao et al. demonstrated that MCC tumor survival requires neuroendocrine-lineage transcription factors, which are recruited to superenhancers (SEs) with the viral small T antigen oncoprotein to promote the neuroendocrine Merkel cell lineage of the cancer. Surprisingly, SEs mapped near the MCV integration site in MCC, and two SE-associated neuroendocrine transcription factors drove viral T antigen gene expression. MCV oncogene and neuroendocrine transcriptional network interactions rendered this viral tumorigenesis dependent on the Merkel cell lineage. Together with reports from other groups, the findings explain why MCV-associated cancer is specifically linked to the Merkel cell phenotype and identify epigenetic strategies targeting of lineage-dependent oncogene circuitry to treat virus-positive MCC.