Defining mechanisms that generate intratumour heterogeneity and branched evolution may inspire novel therapeutic approaches to limit tumour diversity and adaptation. SETD2 (Su(var), Enhancer of zeste, Trithorax-domain containing 2) trimethylates histone-3 lysine-36 (H3K36me3) at sites of active transcription and is mutated in diverse tumour types, including clear cell renal carcinomas (ccRCCs). Distinct SETD2 mutations have been identified in spatially separated regions in ccRCC, indicative of intratumour heterogeneity. In this study, we have addressed the consequences of SETD2 loss-of-function through an integrated bioinformatics and functional genomics approach. We find that bi-allelic SETD2 aberrations are not associated with microsatellite instability in ccRCC. SETD2 depletion in ccRCC cells revealed aberrant and reduced nucleosome compaction and chromatin association of the key replication proteins minichromosome maintenance complex component (MCM7) and DNA polymerase δ hindering replication fork progression, and failure to load lens epithelium-derived growth factor and the Rad51 homologous recombination repair factor at DNA breaks. Consistent with these data, we observe chromosomal breakpoint locations are biased away from H3K36me3 sites in SETD2 wild-type ccRCCs relative to tumours with bi-allelic SETD2 aberrations and that H3K36me3-negative ccRCCs display elevated DNA damage in vivo. These data suggest a role for SETD2 in maintaining genome integrity through nucleosome stabilization, suppression of replication stress and the coordination of DNA repair.

Integration of aCGH and gene expression data identified copy number aberrations and novel genes with prognostic potential in OAC.

Renal cell carcinoma (RCC) is a constellation of malignancies of different histological subtypes arising from the renal parenchyma. The clear cell histological subtype (ccRCC) accounts for around 75% of RCCs and is characterized by distinct genetic abnormalities, of which the loss of function of the von Hippel-Lindau (VHL) tumor suppressor gene is the most common. Inactivation of other tumor suppressor genes such as SETD2, KDM6A, KDM5C and PBRM1 has been reported in ccRCC--notably, the proteins encoded by these genes are involved in histone and chromatin regulation. Furthermore, the PBRM1 and SETD2 genes are located on the short arm of chromosome 3 near the VHL locus. Chromatin and histones modify gene expression and, as a consequence, their function is tightly regulated. Data from RNA interference (RNAi) assays suggest that loss of function of PBRM1 drives proliferation and growth of ccRCC, but the clinical relevance of this is unclear and restoring the function of these genes for therapeutic purposes is likely to be challenging. An improved understanding of histone and chromatin regulation in RCC biology and the consequences of intratumor heterogeneity might identify novel targets in RCC and present alternative therapeutic opportunities.