Identification of focally amplified lineage-specific super-enhancers in human epithelial cancers
NATURE GENETICS
Authors: Zhang, Xiaoyang; Choi, Peter S.; Francis, Joshua M.; Imielinski, Marcin; Watanabe, Hideo; Cherniack, Andrew D.; Meyerson, Matthew
Abstract
Whole-genome analysis approaches are identifying recurrent cancer-associated somatic alterations in noncoding DNA regions. We combined somatic copy number analysis of 12 tumor types with tissue-specific epigenetic profiling to identify significant regions of focal amplification harboring super-enhancers. Copy number gains of noncoding regions harboring super-enhancers near KLF5, USP12, PARD6B and MYC are associated with overexpression of these cancer-related genes. We show that two distinct focal amplifications of super-enhancers 3' to MYC in lung adenocarcinoma (MYC-LASE) and endometrial carcinoma (MYC-ECSE) are physically associated with the MYC promoter and correlate with MYC overexpression. CRISPR/Cas9-mediated repression or deletion of a constituent enhancer within the MYC-LASE region led to significant reductions in the expression of MYC and its target genes and to the impairment of anchorage independent and clonogenic growth, consistent with an oncogenic function. Our results suggest that genomic amplification of super-enhancers represents a common mechanism to activate cancer driver genes in multiple cancer types.
Downregulation of WDR20 due to loss of 14q is involved in the malignant transformation of clear cell renal cell carcinoma
CANCER SCIENCE
Authors: Takahashi, Mika; Tsukamoto, Yoshiyuki; Kai, Tomoki; Tokunaga, Akinori; Nakada, Chisato; Hijiya, Naoki; Uchida, Tomohisa; Daa, Tsutomu; Nomura, Takeo; Sato, Fuminori; Mimata, Hiromitsu; Matsuura, Keiko; Moriyama, Masatsugu
Abstract
Previously, we reported that genomic loss of 14q occurs more frequently in high-grade than in low-grade clear cell renal cell carcinomas (ccRCCs), and has a significant impact on the levels of expression of genes located in this region, suggesting that such genes may be involved in the malignant transformation of ccRCCs. Here, we found that six of the genes located in the minimal common region of 14q loss were significantly downregulated in high-grade ccRCCs due to copy number loss. Using a dataset from The Cancer Genome Atlas Research Network, we found that downregulation of one of these six genes, WDR20, was significantly associated with poorer outcome in patients with ccRCC, suggesting that WDR20 downregulation may be involved in the malignant transformation of ccRCCs. In functional assays, exogenous WDR20 significantly inhibited the growth of RCC cell lines and induced apoptosis. Interestingly, the phosphorylation levels of ERK and protein kinase B/AKT, which reportedly contribute to the malignant phenotype of RCC cells, were clearly reduced by exogenous expression of WDR20. Thus, our data suggest that downregulation of WDR20 due to 14q loss may be involved in the malignant transformation of ccRCCs, in part through activation of the ERK and protein kinase B/AKT pathways.