Up-regulated LINC00261 predicts a poor prognosis and promotes a metastasis by EMT process in cholangiocarcinoma

Objective: LINC00261 plays a vital role in tumorigenesis and metastasis of digestive system cancer. However, an influence of LINC00261 on cholangiocarcinoma has a little research. There, we investigated clinical role and molecular mechanisms of LINC00261 in cholangiocarcinoma. Methods: The qRT-PCR was performed for the detection of LINC00261 level in 50 paired specimens from CCA patients and six cell lines. Cell proliferation were explored by CCK-8 and colony formation assays in QBC939 and RBE cells after transfected with si-LINC00261 or si-NC. Then, AO/EB double fluorescence staining and flow cytometric assays were performed to assess cell apoptosis. Transwell and wound healing assays were selected to evaluate migratory and invasive property of cells. Protein levels, such as PCNA, Box, Bcl-2, and several epithelial-to-mesenchymal transition markers, including E-cadherin, N-cadherin and Vimentin, were detected by western blot assays. Furthermore, we use a R2 platform to evaluate the correlation between LINC00261 and EMT makers and predict the overall survival and relapse-free survival for CCA patients by the expression of LINC00261/EMT makers. Results: LINC00261 was overexpressed in cancerous tissues and CCA cell lines compared with adjacent tissues and HIBEC, respectively. Up-regulation of LINC00261 was related to larger tumor size (p = 0.009), positive lymph node metastasis (p = 0.021), advanced TNM stages (p = 0.017) and higher postoperative recurrence (p = 0.009) for CCA patients. Additionally, univariate and multivariate analysis displayed that LINC00261 an independent prognostic factor in CCA patients. Knockdown of LINC00261 expression in RBE and QBC939 cell lines inhibited cell proliferation, migration and invasion property and increased cell apoptosis and the EMT progression. Moreover, there was a strong correlation between LINC00261 and E-cadherin (CDH1) (p < 0.05), and low expression of E-cadherin (CDH1) has a poor overall survival and relapse-free survival in CCA patients (p < 0.05). Conclusion: Overall, high level of LINC00261 in CCA predicts a poor prognosis, and promotes a metastasis via EMT process. Thus, LINC00261 could be a promising biomarker and therapeutic target for CCA, and in the high level of LINC00261 in CCA, E-cadherin or CDH1 might be an effective factor for tumor metastasis or poor prognosis.