The landscape of gene fusions in hepatocellular carcinoma

Abstract

Most hepatocellular carcinoma (HCC) patients are diagnosed at advanced stages and suffer limited treatment options. Challenges in early stage diagnosis may be due to the genetic complexity of HCC. Gene fusion plays a critical function in tumorigenesis and cancer progression in multiple cancers, yet the identities of fusion genes as potential diagnostic markers in HCC have not been investigated.Paired-end RNA sequencing was performed on noncancerous and cancerous lesions in two representative HBV-HCC patients. Potential fusion genes were identified by STAR-Fusion in STAR software and validated by four publicly available RNA-seq datasets. Fourteen pairs of frozen HBV-related HCC samples and adjacent non-tumor liver tissues were examined by RT-PCR analysis for gene fusion expression.We identified 2,354 different gene fusions in the two HBV-HCC patients. Validation analysis against the four RNA-seq datasets revealed only 1.8% (43/2,354) as recurrent fusions that were supported by public datasets. Comparison with four fusion databases demonstrated that three (HLA-DPB2-HLA-DRB1, CDH23-HLA-DPB1, and C15orf57-CBX3) out of 43 recurrent gene fusions were annotated as disease-related fusion events. Nineteen were novel recurrent fusions not previously annotated to diseases, including DCUN1D3-GSG1L and SERPINA5-SERPINA9. RT-PCR and Sanger sequencing of 14 pairs of HBV-related HCC samples confirmed expression of six of the new fusions, including RP11-476K15.1-CTD-2015H3.2.Our study provides new insights into gene fusions in HCC and could contribute to the development of anti-HCC therapy. RP11-476K15.1-CTD-2015H3.2 may serve as a new therapeutic biomarker in HCC.