Fig. 1

Decreased cNFIB expression is correlated with ICC metastasis and poor prognosis. (A) 17,169 circRNAs identified in this study have been documented in circBase. (B) Volcano plot of circRNAs that were differentially expressed in 15 ICC tissues with or without extrahepatic metastases identified by circRNA-seq. Vertical dotted lines correspond to up-regulation (Log₂FC > 1) and down-regulation (Log₂FC < − 1). Horizontal dotted line corresponds to adjusted P = 0.05. (C) Results from qRT-PCR validated 3 upregulated and 5 downregulated circRNAs in 20 ICC tissues (cohort1) from patients who experienced postsurgical metastases and 20 ICC tissues from patients that did not (mean ± SD, unpaired Student’s t test). (D) Scheme showing the genomic locus and production of cNFIB. Specific divergent primer was designed targeting the back-splice junction and qRT-PCR products were confirmed by Sanger sequencing. (E) Relative RNA levels of cNFIB in 55 paired ICC and noncancerous tissues (mean ± SD, paired Student’s t test, ***P < 0.001). (F) Kaplan-Meier curves showing the OS (left) and RFS (right) of 114 ICC patients matched by PSM analysis. Patients were stratified by the median expression levels of cNFIB. Log-rank test was used. (G) Multivariate analyses showing hazard factors for OS (left) and RFS (right) of the matched cohort. Data were shown as mean ± SD, *P < 0.05; **P < 0.01; ***P < 0.001. Abbreviations: ns, no significance; Met, metastasis; No met, metastasis; TNM, tumor-node-metastasis; CI, confidence interval; ICC, intrahepatic cholangiocarcinoma; OS, overall survival; RFS, recurrence-free survival