Panoply™ Human ABL1 Knockdown Stable Cell Line

Here, researchers investigated whether ABL proto-oncogene 1 non-receptor tyrosine kinase (ABL1) is involved in the development and progression of hepatocellular carcinoma (HCC). The study showed that ABL1 expression levels were higher in HCC tissue than in non-tumor liver tissue and were associated with shorter patient survival. Hep^WT mice carrying MET and catenin β1 transposons developed liver tumors with a median survival of 64 days. In contrast, Hep^Abl–/– mice carrying these transgenes showed a 50% reduction in tumor volume and an extended median survival to 81 days. Knockdown of ABL1 in human HCC cells reduced cell proliferation, decreased the growth of xenograft tumors in mice, and reduced MYC expression, which in turn reduced NOTCH1 expression. Knockdown of NOTCH1 or MYC in HCC cells significantly inhibited cell growth. Overexpression of NOTCH1 or MYC in human HCC cells promoted cell proliferation and reversed the phenotype caused by ABL1 knockdown. The levels of phosphorylated (activated) ABL1 in human HCC specimens were positively correlated with the levels of MYC and NOTCH1. Nilotinib reduced the expression of MYC and NOTCH1 in HCC cell lines, decreased the growth of xenograft tumors in mice, and delayed the growth of liver tumors in mice carrying MET and catenin β1 transposons, reducing the levels of MYC and NOTCH1 in tumor tissue. Therefore, ABL1 inhibitors may be useful for the treatment of HCC.

To determine the molecular mechanisms by which ABL1 promotes liver cancer cell proliferation, researchers performed RNA sequencing analysis using scrambled-control and ABL1 knockdown cells, followed by gene set enrichment analysis (GSEA). The results showed that the NOTCH signaling pathway was one of the significantly downregulated gene pathways after ABL1 knockdown (Figure 1A and B). The NOTCH signaling pathway has been shown to play an important role in tumor cell growth in various cancers, including liver cancer. Therefore, the researchers hypothesized that ABL1 knockdown inhibits liver cancer cell proliferation by suppressing the NOTCH signaling pathway. Real-time polymerase chain reaction (RT-PCR) experiments confirmed that ABL1 knockdown reduced the mRNA expression levels of several NOTCH signaling pathway genes, including NOTCH1, NOTCH3, JAG1, LFENG, and DTX1 (Figure 1C). The researchers also found that the expression of NOTCH downstream target genes (including CyclinD1, NRARP, HES1, and HES2) was reduced in ABL1 knockdown liver cancer cells (Figure 1D), indicating that NOTCH signaling pathway activity was inhibited in ABL1 knockdown cells.

Figure 1. ABL1 knockdown inhibits HCC cell proliferation by decreasing NOTCH1 expression. (Wang F, et al., 2020)