Accumulation of Molecular Aberrations Distinctive to Hepatocellular Carcinoma Progression.

TitleAccumulation of Molecular Aberrations Distinctive to Hepatocellular Carcinoma Progression.
Publication TypeJournal Article
Year of Publication2020
AuthorsMidorikawa, Y, Yamamoto, S, Tatsuno, K, Renard-Guillet, C, Tsuji, S, Hayashi, A, Ueda, H, Fukuda, S, Fujita, T, Katoh, H, Ishikawa, S, Covington, KR, Creighton, CJ, Sugitani, M, Wheeler, DA, Shibata, T, Nagae, G, Takayama, T, Aburatani, H
JournalCancer Res
Date Published2020 Sep 15
Keywordsbeta Catenin, Carcinoma, Hepatocellular, Disease Progression, DNA Methylation, DNA, Neoplasm, Epigenesis, Genetic, Gene Dosage, Gene Drive Technology, Gene Expression, Genes, cdc, Genes, p53, Histone-Lysine N-Methyltransferase, Humans, Liver Neoplasms, Mutation, Myeloid-Lymphoid Leukemia Protein, Oncogene Protein v-akt, Phosphatidylinositol 3-Kinases, Probability, Reverse Transcriptase Polymerase Chain Reaction, RNA, Neoplasm, Sequence Analysis, DNA, Telomerase, Transcriptional Activation, Up-Regulation, Wnt Proteins

Cancer develops through the accumulation of genetic and epigenetic aberrations. To identify sequential molecular alterations that occur during the development of hepatocellular carcinoma (HCC), we compared 52 early and 108 overt HCC samples by genome sequencing. Gene mutations in the p53/RB1 pathway, WNT pathway, MLL protein family, SWI/SNF complexes, and AKT/PI3K pathway were common in HCC. In the early phase of all entities, was the most frequently upregulated gene owing to diverse mechanisms. Despite frequent somatic mutations in driver genes, including and , early HCC was a separate molecular entity from overt HCC, as each had a distinct expression profile. Notably, WNT target genes were not activated in early HCC regardless of mutation status because β-catenin did not translocate into the nucleus due to the E-cadherin/β-catenin complex at the membrane. Conversely, WNT targets were definitively upregulated in overt HCC, with mutation associated with downregulation of and hypomethylation of CpG islands in target genes. Similarly, cell-cycle genes downstream of the p53/RB pathway were upregulated only in overt HCC, with or gene mutations associated with chromosomal deletion of 4q or 16q. HCC was epigenetically distinguished into four subclasses: normal-like methylation, global-hypomethylation (favorable prognosis), stem-like methylation (poor prognosis), and CpG island methylation. These methylation statuses were globally maintained through HCC progression. Collectively, these data show that as HCC progresses, additional molecular events exclusive of driver gene mutations cooperatively contribute to transcriptional activation of downstream targets according to methylation status. SIGNIFICANCE: In addition to driver gene mutations in the WNT and p53 pathways, further molecular events are required for aberrant transcriptional activation of these pathways as HCC progresses.

Alternate JournalCancer Res
PubMed ID32641413

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