RESUMO
Genome rearrangements, a hallmark of cancer, can result in gene fusions with oncogenic properties. Using DNA paired-end-tag (DNA-PET) whole-genome sequencing, we analyzed 15 gastric cancers (GCs) from Southeast Asians. Rearrangements were enriched in open chromatin and shaped by chromatin structure. We identified seven rearrangement hot spots and 136 gene fusions. In three out of 100 GC cases, we found recurrent fusions between CLDN18, a tight junction gene, and ARHGAP26, a gene encoding a RHOA inhibitor. Epithelial cell lines expressing CLDN18-ARHGAP26 displayed a dramatic loss of epithelial phenotype and long protrusions indicative of epithelial-mesenchymal transition (EMT). Fusion-positive cell lines showed impaired barrier properties, reduced cell-cell and cell-extracellular matrix adhesion, retarded wound healing, and inhibition of RHOA. Gain of invasion was seen in cancer cell lines expressing the fusion. Thus, CLDN18-ARHGAP26 mediates epithelial disintegration, possibly leading to stomach H(+) leakage, and the fusion might contribute to invasiveness once a cell is transformed.
Assuntos
Claudinas/genética , Proteínas Ativadoras de GTPase/genética , Proteínas de Fusão Oncogênica/metabolismo , Neoplasias Gástricas/patologia , Sequência de Aminoácidos , Animais , Adesão Celular , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Clatrina/farmacologia , Claudinas/metabolismo , Cães , Endocitose/efeitos dos fármacos , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Transição Epitelial-Mesenquimal , Proteínas Ativadoras de GTPase/metabolismo , Células HeLa , Humanos , Células MCF-7 , Células Madin Darby de Rim Canino , Dados de Sequência Molecular , Proteínas de Fusão Oncogênica/genética , Fenótipo , Neoplasias Gástricas/metabolismo , Proteína rhoA de Ligação ao GTP/antagonistas & inibidores , Proteína rhoA de Ligação ao GTP/metabolismoRESUMO
To survey hepatitis B virus (HBV) integration in liver cancer genomes, we conducted massively parallel sequencing of 81 HBV-positive and 7 HBV-negative hepatocellular carcinomas (HCCs) and adjacent normal tissues. We found that HBV integration is observed more frequently in the tumors (86.4%) than in adjacent liver tissues (30.7%). Copy-number variations (CNVs) were significantly increased at HBV breakpoint locations where chromosomal instability was likely induced. Approximately 40% of HBV breakpoints within the HBV genome were located within a 1,800-bp region where the viral enhancer, X gene and core gene are located. We also identified recurrent HBV integration events (in ≥ 4 HCCs) that were validated by RNA sequencing (RNA-seq) and Sanger sequencing at the known and putative cancer-related TERT, MLL4 and CCNE1 genes, which showed upregulated gene expression in tumor versus normal tissue. We also report evidence that suggests that the number of HBV integrations is associated with patient survival.