Surgical results for intrahepatic cholangiocarcinoma (ICC) remain unsatisfactory due to the high rate of recurrence. Here, we investigated that the expression and roles of tripartite motif‐containing protein 44 (TRIM44) in human ICCs. Firstly, TRIM44 expression was analyzed in several kinds of cancers by referring to public Oncomine database, and the expressions of TRIM44 mRNA and protein were tested in ICC and corresponding paratumorous tissues. Secondly, functions and mechanisms of TRIM44 in ICC cells were further evaluated by TRIM44 interference and cDNA transfection. Finally, the prognostic role of TRIM44 was assessed by Kaplan–Meier and Cox regression. We found that TRIM44 expression was upregulated in ICC tissues compared with corresponding paratumorous tissues, which were consistent with the results from the public cancer database. Knockdown of TRIM44 repressed the invasion and migration of ICC cells, while increased the ICC cell apoptosis. Additionally, high level of TRIM44 was shown to induce ICC cell epithelial to mesenchymal transition (EMT). Mechanistically, a high level of TRIM44 was found to activate MAPK signaling, and a MEK inhibitor, AZD6244, reversed cell EMT and apoptosis endowed by TRIM44 overexpression. Clinically, TRIM44 expression was positively associated with large tumor size (P = 0.035), lymphatic metastasis (P = 0.008) and poor tumor differentiation (P = 0.036). Importantly, patients in TRIM44^high group had shorter overall survival and higher cumulative rate of recurrence than patients in TRIM44^low group. Our results suggest elevated TRIM44 promotes ICC development by inducing cell EMT and apoptosis resistance, and TRIM44 is a valuable prognostic biomarker and promising therapeutic target of ICC.

RING finger protein 38 (RNF38), a member of the RNF protein family, has just emerged as a vital driver of cancer progression. However, the oncogenic mechanisms of RNF38 remain unexplored. Using frozen tumor tissue and tissue microarray from hepatocellular carcinoma (HCC) patients, we tried to probe the expression of RNF38 in HCC and its clinical value. Then the biological functions of RNF38 were analyzed in vivo and vitro. Stable isotope labeling with amino acids (SILAC) in cell culture and co-immunoprecipitation proteomic analyses were combined to reveal the potential mechanism of RNF38 in HCC progression. We report that RNF38 expression was markedly higher in HCC tissues than in peritumor tissues. Correspondingly, RNF38 overexpression promoted the HCC cell migration and invasion and inhibited apoptosis both in vitro and in vivo. And elevated RNF38 expression induced HCC cell epithelial-mesenchymal transition by facilitating transforming growth factor-β (TGF-β) signaling via ubiquitinating and degrading neuroblast differentiation-associated protein (AHNAK), a well-established inhibitor of TGF-β signaling. Furthermore, AHNAK interference restored the HCC cell invasion and metastasis deprived by RNF38 downregulation. Clinically, elevated RNF38 and transforming growth factor beta receptor 1 (TGFBR1) expression was related to short overall survival (OS) and high cumulative recurrence rates in HCC patients. High levels of RNF38 promote HCC by facilitating TGF-β signaling and are a novel marker for predicting the prognosis of HCC patients and a potential therapeutic target in HCC.

Background: The role of the membrane-associated RING-CH (MARCH) family in carcinogenesis has been widely studied, but the member of this family, RNF173, has not yet been thoroughly explored in the context of hepatocellular carcinoma (HCC). Methods: With the use of an HCC tissue microarray and IHC staining, we aim to determine the differential expression of RNF173 in HCC patients and its clinical significance. The biological role of RNF173 is investigated through in vitro and in vivo experiments. RNA sequencing, mass spectrometry, and immunoprecipitation are performed to uncover the underlying mechanism of RNF173's impact on the development of HCC. Results: The mRNA and protein levels of RNF173 were significantly lower in HCC tissues than in normal tissues. HCC patients with low RNF173 expression had shorter overall survival and recurrence-free survival, and RNF173 was significantly correlated with tumor number, tumor capsule, tumor differentiation, and BCLC stage. In addition, in vitro and in vivo experiments showed that RNF173 downregulation exacerbated tumor progression, including migration, invasion, and proliferation. GRB2 is a key molecule in the RAF/MEK/ERK pathway. RNF173 inhibits the RAF/MEK/ERK signaling by ubiquitinating and degrading GRB2, thereby suppressing HCC cell proliferation, invasion and migration. Combining clinical samples, we found that HCC patients with high RNF173 and low GRB2 expression had the best prognosis. Conclusion: RNF173 inhibits the invasion and metastasis of HCC by ubiquitinating and degrading GRB2, thereby suppressing the RAF/MEK/ERK signaling pathway. RNF173 is an independent risk factor for the survival and recurrence of HCC patients. RNF173 may serve as a novel prognostic molecule and potential therapeutic target for HCC. Graphical Graphical abstract Model of RNF173 on RAF/MEK/ERK signaling. RNF173 knockdown resulted in impaired ubiquitination and degradation of GRB2, leading to the activation of the RAF/MEK/ERK signaling pathway and promotion of invasion and metastasis in HCC cells.

Globally, hepatocellular carcinoma (HCC) is one of the most common causes of cancer-associated mortalities. It has a high rate of metastasis and recurrence, which predict a poor prognosis. G-protein-coupled receptor (GPCR)-kinase interacting protein-1 (GIT1) is a multifunctional scaffold protein that mediates the progression of various tumors. Studies have correlated GIT1 with HCC, however, these correlations have not been fully elucidated. Therefore, we aimed at evaluating the expression of GIT1 in HCC tissues and cells, and to investigate its role and potential mechanisms in HCC progression. The expression levels of GIT1 in HCC tissues and other cancers was determined by using the Oncomine and TCGA databases. Functional analysis of GIT1 in HCC was evaluated through in vitro and in vivo experiments, whereby, HCC cells were transfected with synthetically overexpressed and short hairpin RNA (shRNA) lentivirus-mediated plasmids. Kaplan–Meier and Cox regression methods were used to establish the associations between GIT1 and clinical outcomes of 158 HCC patients. GIT1 was found to be elevated in HCC tissues where it promoted the invasion, migration, and proliferation of HCC cells. Moreover, the overexpression of GIT1 prompted epithelial-mesenchymal transition (EMT) by activating extracellular regulated kinase 1/2 (ERK1/2) pathway, which was shown to be reversed by SCH772984, a specific ERK1/2 inhibitor. GIT1 was also found to be associated with malignant features of HCC, leading to a poorer prognosis. In conclusion, GIT1 promotes HCC progression by inducing EMT and may reflect the course of HCC patients. Graphical Abstract

Rad51, a DNA-repair-related gene, has been reported to be involved in multiple cancers. However, its link with immune infiltration in liver cancer still unknown. Therefore, more research into the roles and activities of Rad51 in hepatocellular carcinoma (HCC) is required. The International Cancer Genome Consortium (ICGC) was used to identify the DNA repair gene Rad51, and has been proved to be overexpressed in HCC patients. We plotted the Kapan-Meier curve, demonstrating that patients with high expression of Rad51 have a poor prognosis. By analyzing the patient data, we discovered that high expression of Rad51 in HCC is linked to clinical stage, pathological T stage, grade, and age. Rad51 was found to be an independent prognostic factor for HCC patients using the multivariate cox model. Moreover, Rad51 expression was found to be associated with the infiltration of immune cells (B cells, CD4 + T cells, CD8 + T cells, neutrophils, macrophages, and dendritic cells) and was intimately linked to the expression of immune cell markers in HCC. Through the analysis of differentially coexpressed genes (DCGs) of Rad51, GO and KEGG enrichment analyses suggested that the expression level of Rad51 might be relevant to neuroactive ligand-receptor interactions, the cell cycle, DNA replication, homologous recombination, oocyte meiosis, and the Fanconi anemia pathway. These findings indicated that Rad51 is a valuable biomarker for the prognosis of patients with liver cancer and that its expression has a significant correlation with immune infiltrations. Abbreviations: HCC: hepatocellular carcinoma; ICGC: International Cancer Genome Consortium TCGA: The Cancer Genome Atlas; TIMER: Tumor Immune Estimation Resource; CAF: Cancer-associated fibroblast; GEPIA: Gene Expression Profiling Interactive Analysis; GSEA: Gene set enrichment analysis; OS: overall survival; PFS: progression-free survival; RFS: relapse-free survival; DSS: disease-specific survival. Partial cor: partial correlation coefficient; HPA: Human Protein Atlas; GO: Gene Ontology; KEGG: Kyoto Encyclopedia of Genes and Genomes; CAF: Cancer-associated fibroblast; DCGs: differentially co-expressed genes Graphical Abstract

Circular RNAs are known to regulate the biological processes of hepatocellular carcinoma (HCC), and humans with Down syndrome are at low risk of developing solid tumors due to the amplification of several tumor suppressor genes on human chromosome 21 (HSA21). Here, we aimed to investigate the potential role of circRNAs originating from HSA21 in the progression of HCC. CircRNA-sequencing was performed to analyze differentially expressed circRNAs in 4 HCC and peritumor tissues, and circRNAs originating from HSA21 were further analyzed. Circ_0061984 (circPTTG1IP) was chosen for further study because it showed the lowest expression in HCC tissues, and qRT-PCR was used to confirm the expression of circPTTG1IP in HCC patient tissues. The biological function of circPTTG1IP was detected in HCC cells both in vivo and in vitro. Moreover, luciferase reporter assays, circRNA immunoprecipitation, and fluorescence in situ hybridization (FISH) were used to investigate the potential mechanism of circPTTG1IP. Finally, the possible mechanisms of filgotinib in circPTTG1IP-driven HCC were assessed. CircPTTG1IP expression was decreased in HCC compared to peritumoral tissues. Moreover, low circPTTG1IP expression was revealed to be associated with a poor prognosis of HCC patients. Elevation of circPTTG1IP was revealed to inhibit HCC development both in vitro and in vivo. Mechanistically, circPTTG1IP was shown to function as a competing endogenous RNA (ceRNA) of RNF125 by binding miR-16-5p to increase the level of the E3 ubiquitin ligase RNF125, which further ubiquitinated and degraded JAK1 protein. Finally, we demonstrated that administration of filgotinib, a JAK1 inhibitor, restricted HCC progression induced by low circPTTG1IP expression. Thus, we revealed that circPTTG1IP is a novel tumor suppresser circRNA in HCC and that a low circPTTG1IP level promotes HCC development via the miR-16-5p/RNF125/JAK1 axis. Patients with low circPTTG1IP may benefit from filgotinib treatment.