The Relationship Of YB-1 With Proliferation And Multi-drug Resistance In Intrahepatic Cholangiocarcinoma

OBJECTIVE Y-box binding protein-1(YB-1) is a multifunctional protein, its abnormal expression presence in a variety of the tumors. This study intends to clarify the relationship between YB-1 abnormal expression and clinicopathological parameters, prognosis of intrahepatic cholangiocarcinoma. Study the effects of knock-down YB-1 on the proliferation of cholangiocarcinoma cells and its mechanisms. Explore the effects of YB-1 overexpression on multidrug resistance formation in intrahepatic cholangiocarcinoma and its mechanisms.METHODS Detected the expression of YB-1 in 29 cases of intrahepatic cholangiocarcinoma by immunohistochemistry. Evaluated the relationships between different YB-1 cellular localizations and clinicopathological parameters, prognosis of intrahepatic cholangiocarcinoma patients. YB-1 siRNA knock-down YB-1 expression in intrahepatic cholangiocarcinoma cell lines(HCCC-9810 and TKF-1), then the cell proliferation was detected by MTT assay. Real-time PCR and Western blot analyzed cell proliferation indicators and cell cycle-related proteins. The chemosensitivity of YB-1 over-expressed intrahepatic cholangiocarcinoma cells to gemcitabine was detected by MTT assay, and further testing multidrug resistance associated genes transcriptional level changes.RESULTS 75.9% of intrahepatic cholangiocarcinoma tissues had YB-1 positive staining, and 31.0% of them also had YB-1 nuclear positive staining. Correlation statistics showed that YB-1 cytoplasmic positive intrahepatic cholangiocarcinoma patients had increasing tendency of tumor metastasis and tumor microsatellite lesions. While YB-1 nuclear positive correlated with primary tumor staging(P = 0.033), vascular invasion(P = 0.017), postoperative tumor metastasis(P = 0.011) and clinical stages(P = 0.043). Survival analysis showed that, YB-1 high-expressed patient had a tendency of poor prognosis, especially YB-1 nuclear positive patients with a median disease-free survival of 16 months(P = 0.1867) and overall survival of 19 months(P = 0.0001).YB-1 knock-down inhibited the proliferation of cholangiocarcinoma cells. Further analysis showed that p21 protein expression was up-regulated, and cell proliferation indicators PCNA and Ki67 decreased. Western blot analysis showed that phosphorylation of CDK and Cyclin D1 expression levels were down-regulated, while E2F1 transcriptional level did not change.CONCLUSION High expression of YB-1 in intrahepatic cholangiocarcinoma tissues, especially its nuclear expression associated with tumor progression, and it is a predictor of patient’s poor prognosis. Down-regulated YB-1 expression by YB-1 siRNA induced p21 protein expression, then inhibited cell proliferation and cell cycle arrest in intrahepatic cholangiocarcinoma cell. YB-1 may also increase intrahepatic cholangiocarcinoma cell multidrug resistance by up-regulating MDR1 and MRP1 transcriptional level.