Panoply™ Human ROR1 Knockdown Stable Cell Line

Hepatocellular carcinoma (HCC) is a common and deadly cancer; however, little progress has been made in its diagnosis and prognosis. The expression and function of receptor tyrosine kinase ROR1 in HCC have not been previously studied. Here, researchers investigated the expression of ROR1 in HCC cells and evaluated its role in liver cancer development and progression. The results showed that a novel ROR1 antibody specifically detected endogenous ROR1 protein in human and murine HCC cell lines. ROR1 knockdown led to decreased cell proliferation and migration, but enhanced resistance to apoptosis and anoikis. The chemoresistance phenotype exhibited by ROR1 knockdown cells was due to enhanced drug efflux and increased expression of multidrug resistance genes. Therefore, ROR1 is expressed in HCC and participates in disease development and progression by interfering with multiple signaling pathways. The expression level of ROR1 may have potential value for the diagnosis and prognosis of HCC.

Developmental epithelial-mesenchymal transition (EMT) possesses several important characteristics. First, cells lose epithelial cell characteristics, such as decreased expression of keratin, E-cadherin, and other epithelial markers. Second, they acquire mesenchymal characteristics, such as increased expression of N-cadherin and vimentin. This means that cells undergoing EMT have enhanced migration/invasion capabilities. Furthermore, EMT has also been shown to induce cell cycle arrest, resistance to apoptosis, and acquisition of stem cell characteristics. To investigate the contribution of ROR1 to these EMT characteristics, researchers first assessed the migratory ability of ROR1 knockdown PLC and SNU387 cells and control cells. In the Transwell migration assay, ROR1 knockdown cells showed reduced migratory ability (Figure 1a). This unexpected result prompted researchers to investigate whether cell proliferation and cell cycle progression would change due to altered ROR1 expression levels. Compared to the control group, ROR1 knockdown SNU387 and PLC cells showed significantly reduced proliferative capacity (Figure 1b). This is consistent with the accumulation of ROR1 knockdown cells in the G1 phase (Figure 1c). Therefore, reduced ROR1 expression contributes to the cell cycle arrest phenotype of EMT, but unexpectedly, it also reduces cell motility.

Figure 1. Analysis of cell cycle, proliferation, and migration capacities of shRNA ROR1-knockdown and control clones. (Cetin M, et al., 2019)