Renal medullary carcinomas (RMC) habor a distinct methylation phenotype

Renal medullary carcinomas (RMC) are rare aggressive tumors of the kidneys, characterized by a -mostly- biallelic loss of SMARCB1. Characteristically, these tumors arise in patients with sickle cell trait or other hemoglobinopathies. Recent molecular and landscaping characterization efforts have unraveled oncogenic pathways that drive tumorigenesis. Among these, gene sets that characterize replicative stress and the innate immune response are upregulated in RMCs. Despite comprehensive genetic and transcriptomic characterizations, commonalities or differences to other SMARCB1 deficient entities so far have not been investigated. We analyzed the methylome of four novel primary RMC and compared it to other, SMARCB1 deficient entities such as rhabdoid tumors (RT) and epithelioid sarcomas using 850K methylation arrays. In accordance with previous gene expression data, we find that RMCs separate from other SMARCB1 deficient entities such as extra-and intracranial rhabdoid tumors, pointing to a potentially different cell of origin and a role of additional mutations or genetic aberrations that may drive tumorigenesis and thus alter the methylome when compared to rhabdoid tumors. In a focused analysis of genes that are important for nephrogenesis, we detected particularly genes that govern early nephrogenesis such as FOXI to be hypomethylated and expressed at high levels in RMC. Overall, our analyses underscore the fact that RMCs represent a separate entity with limited similarities to rhabdoid tumors warranting specific treatment, tailored to the aggressiveness of the disease. The DNA methylation of 4 RMC samples was analyzed.