Objective To investigate the effect of Y-box binding protein 1 (YBX1) on the proliferation and invasion of cholangiocarcinoma cells and its underlying mechanism.

Methods Based on the Cancer Genome Atlas (TCGA) database, the expression of YBX1 in cholangiocarcinoma and its relationship with patient prognosis were analyzed, and verified in cancerous and adjacent non-cancerous tissues of cholangiocarcinoma patients using immunohistochemical staining. The protein expression levels of YBX1 in human normal cholangiocyte HIBEC cells and cholangiocarcinoma cell lines (KMBC, CC-LP-1, and QBC939 cells) were detected by western blotting. KMBC cell lines with YBX1 overexpression and YBX1 knockdown were constructed. The effects of YBX1 on the proliferation, migration, and invasion of KMBC cells were observed through CCK-8 assay, colony formation assay, scratch wound healing assay, and transwell invasion assay. The effects of YBX1 on the activity of the Wnt/β-catenin pathway and the expression of its signaling molecules cyclin A1 (cyclinA1), cyclin-dependent kinase 1 (CDK1), matrix metalloproteinase (MMP)-2, and MMP-9 in KMBC cells were detected by western blotting.

Results TCGA database analysis showed that the expression of YBX1 in cholangiocarcinoma tissues with different pathological stages and different lymph node metastasis status was higher than that in normal cholangiocyte tissues, with a statistically significant difference (P < 0.01 or P < 0.001). High expression of YBX1 was significantly negatively correlated with the overall survival and recurrence-free survival of cholangiocarcinoma patients (P < 0.05). Immunohistochemical staining results showed that the positive expression level of YBX1 in cancerous tissues of cholangiocarcinoma patients was higher than that in adjacent non-cancerous tissues, with a statistically significant difference (P < 0.001). The protein expression levels of YBX1 in cholangiocarcinoma cell lines (KMBC, CC-LP-1, and QBC939 cells) were all higher than those in human normal cholangiocyte HIBEC cells, with statistically significant differences (P < 0.01 or P < 0.001). After successfully constructing KMBC cell lines with stable YBX1 overexpression and YBX1 knockdown, the cell experiment results showed that YBX1 overexpression could promote the proliferation, migration, and invasion of KMBC cells, and up-regulate the expression levels of β-catenin, cyclinA1, CDK1, MMP-2, and MMP-9. YBX1 knockdown could significantly inhibit the proliferation, migration, and invasion of KMBC cells and down-regulate the expression levels of β-catenin, cyclinA1, CDK1, MMP-2, and MMP-9, with statistically significant differences (P < 0.05 or P < 0.01 or P < 0.001).

Conclusion YBX1 promotes the proliferation, migration, and invasion of cholangiocarcinoma cells by activating the Wnt/β-catenin signaling pathway and up-regulating the protein expression of cyclinA1, CDK1, MMP-2 and MMP-9.