RNF173 suppresses RAF/MEK/ERK signaling to regulate invasion and metastasis via GRB2 ubiquitination in Hepatocellular Carcinoma.

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. Video Abstract 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.

Bioinformatics analysis of immune infiltrates and tripartite motif (TRIM) family genes in hepatocellular carcinoma.

Background: The tripartite motif (TRIM) family are important members of the Gene-finger-containing E3 ubiquitin-conjugating enzyme and are involved in the progression of hepatocellular carcinoma (HCC). Previous studies have largely focused on gene expression and molecular pathways, while the underlying role of the TRIM family in the tumor immune microenvironment (TIME) remains poorly understood. Methods: We systematically explored the correlations of prominent TRIM genes with immune checkpoints and immune infiltrates in 231 HCC samples [International Cancer Genome Consortium (ICGC) cohort (n=231); The Cancer Genome Atlas (TCGA) cohort (n=370)]. A prognostic risk model was constructed using the least absolute shrinkage and selection operator (LASSO) algorithm and multivariate Cox regression analysis in the ICGC cohort. Kaplan-Meier curves based on the overall survival (OS) were used to assess differences in survival between clusters. We utilized gene set variation analysis (GSVA) to characterize the differences in biological functions. Based on univariate and multivariate Cox progression analysis, we developed a risk score signature and verified its reliability and validity. The Tumor Immune Single-cell Hub (TISCH) single-cell database was employed to evaluate the correlation of TRIM genes with the tumor microenvironment. Results: Cluster 1 was preferentially associated with a favorable prognosis (P<0.001). The amino acid, fatty acid, and drug metabolism pathways were significantly enriched in cluster 2. A prognosis risk score project was established and evaluated based on the 9 independent prognostic genes (all P<0.05). The immune score and stromal scores of patients with low-risk scores were greater than those of patients with high-risk scores (all P<0.001). However, patients with a high-risk score exhibited lower responses to immune check-point inhibitors (ICIs), sorafenib, and transarterial chemoembolization (TACE) treatment (all P<0.05). Consistently, TRIM genes showed the same influence in the external TCGA cohort. TRIM gene-based signatures were implicated in TIME and their copy-number alterations dynamically impacted the abundance of tumor-infiltrating immune cells. Conclusions: Our findings revealed that MID1, TRIM5, TRIM22, TRIM28, TRIM 31, TRIM37, TRIM38, TRIM47, and TRIM74 could serve as efficient prognostic biomarkers and therapeutic targets in HCC. The identified TRIM gene-based signatures could serve as important TIME mediators in HCC, potentially increasing immune treatment efficacy.