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Although circular RNAs (circRNA) are known to modulate tumor initiation and progression, their role in hepatocellular carcinoma (HCC) metastasis remains poorly understood. Here, three metastasis-associated circRNAs identified in a previous circRNA-sequencing study were screened and validated in two HCC cohorts. CircRPN2 was downregulated in highly metastatic HCC cell lines and HCC tissues with metastasis. Patients with HCC with lower circRPN2 levels displayed shorter overall survival and higher rates of cumulative recurrence. Mechanistic studies in vitro and in vivo revealed that circRPN2 binds to enolase 1 (ENO1) and accelerates its degradation to promote glycolytic reprogramming through the AKT/mTOR pathway, thereby inhibiting HCC metastasis. CircRPN2 also acted as a competing endogenous RNA for miR-183-5p, which increases forkhead box protein O1 (FOXO1) expression to suppress glucose metabolism and tumor progression. In clinical samples, circRPN2 expression negatively correlated with ENO1 and positively correlated with FOXO1, and expression of circRPN2, either alone or in combination with ENO1 and FOXO1, was a novel indicator of HCC prognosis. These data support a model wherein circRPN2 inhibits HCC aerobic glycolysis and metastasis via acceleration of ENO1 degradation and regulation of the miR-183-5p/FOXO1 axis, suggesting that circRPN2 represents a possible therapeutic target in HCC., Significance: The circRNA circRPN2 is a potential prognostic biomarker and therapeutic target in hepatocellular carcinoma that suppresses aerobic glycolysis and metastasis., (©2022 American Association for Cancer Research.)

Infiltrating immune cells in the tumor microenvironment (TME) influence tumor progression and patient prognosis, making them attractive therapeutic targets for immunotherapy research. A deeper understanding of immune cell distributions in the TME in hepatocellular carcinoma (HCC) is needed to identify interactions among different immune cell types that might impact the effectiveness of potential immunotherapies. We performed multiplex immunohistochemistry using a tissue microarray of samples from 302 patients with HCC to elucidate the spatial distributions of immune cell subpopulations (CD3 + , CD4 + , CD8 + , CD66b + , and CD68 + ) in HCC and normal liver tissues. We analyzed the associations between different immune subpopulations using Pearson's correlation. G(r) functions, K(r) functions and Euclidean distance were applied to characterize the bivariate distribution patterns among the immune cell types. Cox regression and Kaplan-Meier analysis were used to evaluate the associations between tumor infiltration by different immune cells and patient outcomes after curative surgery. We also analyzed the relationship between the spatial distribution of different immune cell subpopulations with HCC patient prognosis. We found that the immune cell spatial distribution in the HCC TME is heterogeneous. Our study provides a theoretical basis for HCC immunotherapy., (© 2021 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.)

Background: Long noncoding RNAs (lncRNAs) are functionally associated with cancer development and progression. Although gene copy number variation (CNV) is common in hepatocellular carcinoma (HCC), it is not known how CNV in lncRNAs affects HCC progression and recurrence. We aimed to identify a CNV-related lncRNA involved in HCC progression and recurrence and illustrate its underlying mechanisms and prognostic value., Methods: We analyzed the whole genome sequencing (WGS) data of matched cancerous and noncancerous liver samples from 49 patients with HCC to identify lncRNAs with CNV. The results were validated in another cohort of 238 paired HCC and nontumor samples by TaqMan copy number assay. We preformed Kaplan-Meier analysis and log-rank test to identify lncRNA CNV with prognostic value. We conducted loss- and gain-of-function studies to explore the biological functions of LINC01133 in vitro and in vivo. The competing endogenous RNAs (ceRNAs) mechanism was clarified by microRNA sequencing (miR-seq), quantitative real-time PCR (qRT-PCR), western blot, and dual-luciferase reporter assays. We confirmed the binding mechanism between lncRNA and protein by RNA pull-down, RNA immunoprecipitation, qRT-PCR, and western blot analyses., Results: Genomic copy numbers of LINC01133 were increased in HCC, which were positively related with the elevated expression of LINC01133. Increased copy number of LINC01133 predicted the poor prognosis in HCC patients. LINC01133 overexpression in HCC cells promoted proliferation and aggressive phenotypes in vitro, and facilitated tumor growth and lung metastasis in vivo, whereas LINC01133 knockdown had the opposite effects. LINC01133 sponged miR-199a-5p, resulting in enhanced expression of SNAI1, which induced epithelial-to-mesenchymal transition (EMT) in HCC cells. In addition, LINC01133 interacted with Annexin A2 (ANXA2) to activate the ANXA2/STAT3 signaling pathway., Conclusions: LINC01133 promotes HCC progression by sponging miR-199a-5p and interacting with ANXA2. LINC01133 CNV gain is predictive of poor prognosis in patients with HCC., (© 2021 The Authors. Clinical and Translational Medicine published by John Wiley & Sons Australia, Ltd on behalf of Shanghai Institute of Clinical Bioinformatics.)

Background and Aims: There is growing evidence that single-stranded, circular RNA (circRNA) plays a key role in the development of certain cancers, including hepatocellular carcinoma (HCC). It is less clear, however, what role circRNA plays in HCC metastasis., Approach and Results: In this study, through circRNA sequencing, we identified a circRNA: circASAP1 (a circRNA derived from exons 2 and 3 of the ASAP1 gene, hsa_circ_0085616), which is associated with pulmonary metastasis after curative resection in patients with HCC. CircASAP1 was overexpressed in HCC cell lines with high metastatic potential and in metastatic HCCs. In vitro, circASAP1 promoted cell proliferation, colony formation, migration, and invasion, and in vivo, it enhanced tumor growth and pulmonary metastasis. Mechanism studies showed that circASAP1 acts as a competing endogenous RNA for microRNA 326 (miR-326) and microRNA 532-5p (miR-532-5p), both of which are tumor suppressors in HCC. We found that mitogen-activated protein kinase (MAPK) 1 and colony stimulating factor (CSF)-1 were direct common targets for microRNA 326 (miR-326) and microRNA 532-5p (miR-532-5p), which were regulated by circASAP1. CircASAP1 promotes HCC cell proliferation and invasion by regulating miR-326/miR-532-5p-MAPK1 signaling and, furthermore, mediates tumor-associated macrophage infiltration by regulating the miR-326/miR-532-5p-CSF-1 pathway. Clinical HCC samples exhibited a positive correlation between circASAP1 expression and levels of CSF-1, MAPK1, and CD68+ tumor-associated macrophages, all of which were predictive of patient outcomes., Conclusion: We identified circASAP1 as a key regulator of HCC metastasis that acts on miR-326/miR-532-5p-MAPK1/CSF-1 signaling and serves as a prognostic predictor in patients with HCC., (© 2020 by the American Association for the Study of Liver Diseases.)

Aim: The MAGE family member H1 (MAGEH1) belongs to melanoma-associated antigen (MAGE) superfamily. The role of MAGEH1 in hepatocellular carcinoma (HCC) is largely undefined., Materials & Methods: We used quantitative reverse transcription PCR and immunohistochemistry to detect MAGEH1 expression in HCC tissues. CCK-8 assay, wound healing migration assay and Transwell Matrigel invasion assay were used to measure HCC cell proliferation, migration and invasion ability., Results:  MAGEH1 expression was downregulated in HCC tumor tissues compared with adjacent normal liver tissues and in samples from patients with tumor recurrence. MAGEH1 reduced HCC cell proliferation, migration and invasion ability. Low MAGEH1 expression was significantly correlated with poor prognosis in HCC patients., Conclusion:  MAGEH1 may serve as a potential biomarker and a new prognostic factor for HCC.

The semaphorins were originally identified as having roles as guidance cues during neural development. Class 3 semaphorins are involved in cancer progression. However, the roles of class 3 semaphorins in hepatocellular carcinoma (HCC) are unknown. We examined the expression levels of class 3 semaphorins in HCC cell lines with different metastatic potential and in carcinoma tissue samples. The results indicated that Semaphorin 3A expression was up-regulated in metastatic cell lines and in samples from patients with tumor recurrence. Cell functional studies revealed that Semaphorin 3A promoted HCC cell proliferation, migration, and invasion. Animal studies indicated that Semaphorin 3A overexpression enhanced tumor growth and lung metastasis. Semaphorin 3A also acted as a chemoattractant involved in direct recruitment of macrophages in vitro, and facilitated tumor-associated macrophage (TAM) infiltration in vivo. Multivariate analysis revealed that Semaphorin 3A expression alone, or combined with the number of TAMs, can be an independent predictor for overall survival time and time to recurrence. Overall, the results suggested that Semaphorin 3A increased TAM infiltration and promoted HCC progression. Semaphorin 3A expression alone, or combined with the number of TAMs, is a new prognostic factor and potential target for the treatment of HCC., Competing Interests: The authors disclose no conflicts.