The carcinogenic role of FASN by regulating lipid metabolism reprogramming has been well-established in multiple tumors. However, whether mechanisms during intrahepatic cholangiocarcinoma (ICC) progression, such as circRNAs, regulate FASN expression remains unknown. Here we demonstrate a lipid metabolism-related circRNA, circMBOAT2 (hsa_circ_0007334 in circBase), frequently upregulated in ICC tissues, and positively correlated with ICC malignant features. CircMBOAT2 knockdown inhibits the growth and metastasis of ICC cells. Mechanistically, circMBOAT2 combines with PTBP1 and protects PTBP1 from ubiquitin/proteasome-dependent degradation, impairing the function of PTBP1 to transfer FASN mRNA from the nucleus to the cytoplasm. Moreover, circMBOAT2 and FASN have the same effect on fatty acid profile, unsaturated fatty acids instead of saturated fatty acids are primarily regulated and associated with malignant behaviors of ICC cells. The levels of lipid peroxidation and ROS were significantly higher when FASN was knocked down and recovered when circMBOAT2 was overexpressed. Our results identified that circMBOAT2 was upregulated in ICC and promoted progression by stabilizing PTBP1 to facilitate FASN mRNA cytoplasmic export, which altered lipid metabolic profile and regulated redox homeostasis in ICC, suggesting that circMBOAT2 may serve as an available therapeutic target for ICC with active lipid metabolism.

Background: Intrahepatic cholangiocarcinoma (ICC) is poorly treated due to the presence of an inhibitory immune microenvironment. Tumor-associated macrophages (TAM) are an important component of TME. ALOX5 is an important lipid metabolism enzyme in cancer progression, but the mechanism by which it regulates TAM to promote ICC progression is unknown. The aim of this study was to investigate the potential mechanism of TAM regulation by ALOX5 and the translational effect of targeting ALOX5. Methods: In this study, we investigated the association between the spatial localization of epithelial cells and TAMs by combining scRNA-seq analysis with multiplex immunofluorescence analysis. Through bulk sequencing analysis and spatial analysis, lipid metabolism genes closely related to TAM infiltration were screened. In vitro co-culture model was constructed to verify that ALOX5 and its downstream metabolite LTB4 promote M2 macrophage migration. Bulk sequencing after co-culture combined with single-cell analysis was performed to identify key pathways for up-regulation of M2 macrophage migration. Finally, the effect of CSF1R inhibitor (PLX3397) combined with ALOX5 inhibitor (Zileuton) in vivo was investigated by by xenograft tumor formation experiment in nude mice. Results: ALOX5 in ICC cells was a key lipid metabolism gene affecting the infiltration of M2 macrophages in TME. Mechanically, LTB4, a metabolite downstream of ALOX5, recruited M2 macrophages to migrate around tumor cells by binding to BLT1/BLT2 and activating the PI3K pathway, which ultimately lead to the promotion of ICC progression. Targeting CSF1R in combination with ALOX5 inhibitor effectively reduced tumor volume and M2 macrophage infiltration abundance. Conclusion: In ICC, LTB4, a metabolite secreted by ALOX5 of epithelial cells, binded to BLT1/BLT2 on TAM surface to activate PI3K pathway and promote TAM migration, thus promoting ICC progression. Targeting CSF1R in combination with ALOX5 inhibitor for ICC is a promising combination therapy modality.

Background: The preoperative nutritional status and the immunological status have been reported to be independent prognostic factors of patients with intrahepatic cholangiocarcinoma (ICC). This study aimed to investigate whether prognostic nutritional index (PNI) + albumin–bilirubin (ALBI) could be a better predictor than PNI and ALBI alone in patients with ICC after radical resection.Methods: The prognostic prediction evaluation of the PNI, ALBI, and the PNI+ALBI grade was performed in 373 patients with ICC who underwent radical resection between 2010 and 2018 at six Chinese tertiary hospitals, and external validation was conducted in 162 patients at four other Chinese tertiary hospitals. Overall survival (OS) and relapse-free survival (RFS) were estimated using the Kaplan–Meier method. Multivariate analysis was conducted to identify independent prognostic factors. A time-dependent receiver operating characteristic (ROC) curve and a nomogram prediction model were further constructed to assess the predictive ability of PNI, ALBI, and the PNI+ALBI grade. The C-index and a calibration plot were used to assess the performance of the nomogram models.Results: Univariate analysis showed that PNI, ALBI, and the PNI+ALBI grade were prognostic factors for the OS and RFS of patients with ICC after radical resection in the training and testing sets (p < 0.001). Multivariate analysis showed that the PNI+ALBI grade was an independent risk factor for OS and RFS in the training and testing sets (p < 0.001). Analysis of the relationship between the PNI+ALBI grade and clinicopathological characteristics showed that the PNI+ALBI grade correlated with obstructive jaundice, alpha-fetoprotein (AFP), cancer antigen 19-9 (CA19-9), cancer antigen 125 (CA125), PNI, ALBI, Child–Pugh grade, type of resection, tumor size, major vascular invasion, microvascular invasion, T stage, and N stage (p < 0.05). The time-dependent ROC curves showed that the PNI+ALBI grade had better prognostic predictive ability than the PNI, ALBI, and the Child–Pugh grade in the training and testing sets.Conclusion: Preoperative PNI+ALBI grade is an effective and practical predictor for the OS and RFS of patients with ICC after radical resection.

This study aimed to evaluate the prognostic value of lymph node dissection (LND) in node-negative intrahepatic cholangiocarcinoma (ICC) and identify the appropriately total number of lymph nodes examined (TNLE). Data from node-negative ICC patients who underwent curative intent resection in ten Chinese hepatobiliary centers from January 2010 to December 2018 were collected. Overall survival (OS), relapse-free survival (RFS) and postoperative complications were analyzed. Propensity score matching (PSM) was performed to reduce the bias due to confounding variables in LND group and non-lymph node dissection (NLND) group. The optimal TNLE was determined by survival analysis performed by the X-tile program using the enumeration method. A total of 637 clinically node-negative ICC patients were included in this study, 74 cases were found lymph node (LN) positive after operation. Among the remaining 563 node-negative ICC patients, LND was associated with longer OS but not RFS before PSM (OS: 35.4 vs 26.0 months, p = 0.047; RFS: 15.0 vs 15.4 months, p = 0.992). After PSM, patients in LND group had better prognosis on both OS and RFS (OS: 38.0 vs 23.0 months, p < 0.001; RFS: 15.0 vs 13.0 months, p = 0.029). There were no statistically differences in postoperative complications. When TNLE was greater than 8, OS (48.5 vs 31.1 months, p = 0.025) and RFS (21.0 vs 13.0 months, p = 0.043) were longer in the group with more dissected LNs. Routinely LND for node-negative ICC patients is recommended for it helps accurate tumor staging and associates with better prognosis. The optimal TNLE is more than 8.

Objective: We aimed to evaluate the prognosis and adjuvant chemotherapy (ACT) in intrahepatic cholangiocarcinoma (ICC) patients with different etiology after radical resection. Methods: A total of 448 patients with ICC who underwent radical resection between 2010 and 2018 at ten Chinese tertiary hospitals were analyzed in the study. These patients were divided into conventional ICC (Con-ICC, n = 261, 58.2%), hepatitis B virus ICC (HBV-ICC, n = 102, 22.8%) and hepatolithiasis (Stone-ICC, n = 85,19.0%) subtypes according to different etiology. Propensity score matching (PSM) was conducted to mitigate the baseline differences between Con-ICC and HBV-ICC, Con-ICC and Stone-ICC, HBV-ICC and Stone-ICC subtypes. Results: Univariate and multivariate analysis showed that different etiology was a prognostic factor for overall survival and relapse-free survival, and different etiology was an independent risk factor for overall survival in ICC patients, respectively (P < 0.05). In addition, there was a statistical difference for overall survival in early recurrence patients among the three etiological subtypes (P < 0.05). After PSM, the overall survival of patients with Stone-ICC was worse than those of Con-ICC and HBV-ICC subtypes (P < 0.05), while the relapse-free survival of patients with Stone-ICC was equivalent to patients with Con-ICC and HBV-ICC (P > 0.05). In Stone-ICC patients, the median overall survival was 16.0 months and 29.7 months, and the median relapse-free survival was 9.0 months and 20.0 months for non-ACT and ACT patients, respectively (P < 0.05). Conclusion: The prognosis of Stone-ICC patients was significantly worse than those of Con-ICC and HBV-ICC patients. Interestingly, postoperative adjuvant chemotherapy can improve the prognosis of Stone-ICC patients effectively.