Abstract
We investigated whether ABL proto-oncogene 1, non-receptor tyrosine kinase (ABL1) is involved in development of hepatocellular carcinoma (HCC). We analyzed clinical and gene expression data from The Cancer Genome Atlas. Albumin-Cre (HepWT) mice and mice with hepatocyte-specific disruption of Abl1 (HepAbl-/- mice) were given hydrodynamic injections of plasmids encoding the Sleeping Beauty transposase and transposons with the MET gene and a catenin β1 gene with an N-terminal truncation, which induces development of liver tumors. Some mice were then gavaged with the ABL1 inhibitor nilotinib or vehicle (control) daily for 4 weeks. We knocked down ABL1 with short hairpin RNAs in Hep3B and Huh7 HCC cells and analyzed their proliferation and growth as xenograft tumors in mice. We performed RNA sequencing and gene set enrichment analysis of tumors. We knocked down or overexpressed NOTCH1 and MYC in HCC cells and analyzed proliferation. We measured levels of phosphorylated ABL1, MYC, and NOTCH1 by immunohistochemical analysis of an HCC tissue microarray. HCC tissues had higher levels of ABL1 than non-tumor liver tissues, which correlated with shorter survival times of patients. HepWT mice with the MET and catenin β1 transposons developed liver tumors and survived a median 64 days; HepAbl-/- mice with these transposons developed tumors that were 50% smaller and survived a median 81 days. Knockdown of ABL1 in human HCC cells reduced proliferation, growth as xenograft tumors in mice, and expression of MYC, which reduced expression of NOTCH1. Knockdown of NOTCH1 or MYC in HCC cells significantly reduced cell growth. NOTCH1 or MYC overexpression in human HCC cells promoted proliferation and rescued the phenotype caused by ABL1 knockdown. The level of phosphorylated (activated) ABL1 correlated with levels of MYC and NOTCH1 in human HCC specimens. Nilotinib decreased expression of MYC and NOTCH1 in HCC cell lines, reduced the growth of xenograft tumors in mice, and slowed growth of liver tumors in mice with MET and catenin β1 transposons, reducing tumor levels of MYC and NOTCH1. HCC samples have increased levels of ABL1 compared with nontumor liver tissues, and increased levels of ABL1 correlate with shorter survival times of patients. Loss or inhibition of ABL1 reduces proliferation of HCC cells and slows growth of liver tumors in mice. Inhibitors of ABL1 might be used for treatment of HCC.
Highlights
BACKGROUND & AIMSWe investigated whether ABL protooncogene 1, non-receptor tyrosine kinase (ABL1) is involved in development of hepatocellular carcinoma (HCC)
To confirm the results with a larger sample size, we analyzed the The Cancer Genome Atlas (TCGA) database and confirmed that ABL1 was expressed at higher levels in HCCs compared to normal liver tissues (Figure 1A)
We found that the level of p-ABL1 (p-Tyr412) is largely absent in normal liver tissues, but is abundant in HCC specimens (Figure 1C and E)
Summary
BACKGROUND & AIMSWe investigated whether ABL protooncogene 1, non-receptor tyrosine kinase (ABL1) is involved in development of hepatocellular carcinoma (HCC). We knocked down ABL1 with short hairpin RNAs in Hep3B and Huh[7] HCC cells and analyzed their proliferation and growth as xenograft tumors in mice. Knockdown of ABL1 in human HCC cells reduced proliferation, growth as xenograft tumors in mice, and expression of MYC, which reduced expression of NOTCH1. NOTCH1 or MYC overexpression in human HCC cells promoted proliferation and rescued the phenotype caused by ABL1 knockdown. Nilotinib decreased expression of MYC and NOTCH1 in HCC cell lines, reduced the growth of xenograft tumors in mice, and slowed growth of liver tumors in mice with MET and catenin b1 transposons, reducing tumor levels of MYC and NOTCH1. Loss or inhibition of ABL1 reduces proliferation of HCC cells and slows growth of liver tumors in mice. The oncogene ABL1 might be involved in the pathogenesis of hepatocellular carcinoma (HCC)
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