Hint1 Up-Regulates IκBα by Targeting the β-TrCP Subunit of SCF E3 Ligase in Human Hepatocellular Carcinoma Cells

The role of abnormal ubiquitination in hepatocellular carcinoma pathology

Primary liver cancer is known for its high incidence and fatality rate. Over the years, therapeutic strategies for primary liver cancer have advanced significantly. Nonetheless, a substantial number of patients have not benefited from these methods, underscoring the pressing need for new and effective treatments for primary liver cancer. Ubiquitination is a critical post-translational modification that enables proteins to fulfill their normal biological functions and maintain their expression stability within cells. Importantly, increasing evidence suggests that the progression of liver cancer cells is often accompanied by disruptions in protein ubiquitination and deubiquitination processes. In this comprehensive review, we have compiled pertinent research about dysregulated ubiquitination in hepatocellular carcinoma (HCC) to broaden our understanding in this field. We elucidate the connections between the ubiquitination proteasome system, deubiquitination, and HCC. Furthermore, we shed light on the role of ubiquitination in cells situated within the tumor microenvironment of HCC including its involvement in mediating the activation of oncogenic pathways, reprogramming metabolic processes, and perturbing normal cellular functions. In conclusion, targeting the dysregulation of ubiquitination in HCC holds promise as a prospective and complementary therapeutic approach to existing treatments.

TRIM67 Suppresses TNFalpha-Triggered NF-kB Activation by Competitively Binding Beta-TrCP to IkBa

The transcription factor NF-κB plays an important role in modulation of inflammatory pathways, which are associated with inflammatory diseases, neurodegeneration, apoptosis, immune responses, and cancer. Increasing evidence indicates that TRIM proteins are crucial role in the regulation of NF-κB signaling pathways. In this study, we identified TRIM67 as a negative regulator of TNFα-triggered NF-κB activation. Ectopic expression of TRIM67 significantly represses TNFα-induced NF-κB activation and the expression of pro-inflammatory cytokines TNFα and IL-6. In contrast, Trim67 depletion promotes TNFα-induced expression of TNFα, IL-6, and Mcp-1 in primary mouse embryonic fibroblasts. Mechanistically, we found that TRIM67 competitively binding β-transducin repeat-containing protein (β-TrCP) to IκBα results inhibition of β-TrCP-mediated degradation of IκBα, which finally caused inhibition of TNFα-triggered NF-κB activation. In summary, our findings revealed that TRIM67 function as a novel negative regulator of NF-κB signaling pathway, implying TRIM67 might exert an important role in regulation of inflammation disease and pathogen infection caused inflammation.

Genetic Fine Mapping and Genomic Annotation Defines Causal Mechanisms at A Novel Colorectal Cancer Susceptibility Locus in Han Chinese

Genome-wide association studies of colorectal cancer (CRC) have identified two risk SNPs. The characterization of these risk regions in diverse racial groups with different linkage disequilibrium structure would aid in localizing the causal variants. Herein, fine mapping of the established CRC loci was carried out in 1,508 cases and 1,482 controls obtained from the Han Chinese population. One distinct association signal was identified at these loci, where fine mapping implicated rs1010208 as a functional locus. Next, the candidate target genes of functional SNP rs1010208 were analyzed using data from TCGA databases by expression quantitative trait loci analysis method; the data from Peking University People's Hospital were utilized for verification. The dual-luciferase reporter system analysis confirmed that rs1010208 is a regulatory region that can be mutated to decrease the expression of HINT1, resulting in proliferation and invasiveness of CRC.

β-TrCP1 promotes cell proliferation via TNF-dependent NF-κB activation in diffuse large B cell lymphoma

Diffuse large B cell lymphoma (DLBCL), a heterogeneous group of invasive disease, is the most common type of B-cell non-Hodgkin's lymphomas. The mechanism of its development is closely related to the constitutive activation of NF-κB. In this study, we investigated the function and the mechanism of β-TRCP1 in DLBCL. CCK8 and EdU assays showed that β-TRCP1 could promote the growth of DLBCL cells under the stimulation of TNFα. Furthermore, overexpression of β-TRCP1 enhanced NF-κB activation in the presence of TNFα. Moreover, ectopic expression of β-TRCP1 decreased IκB-α expression but increased phospho-p65 expression. In addition, β-TRCP1 promoted cell cycle progression by accelerating G1-S phase transition. We also found that silencing of β-TrCP1 increased mitoxantrone-induced cell growth arrest and apoptosis. Based on these, we proposed that the expression of β-TRCP1 promoted cell proliferation via TNF-dependent NF-κB activation in DLBCL cells.

Inhibition of neddylation modification by MLN4924 sensitizes hepatocellular carcinoma cells to sorafenib

Sorafenib remains the standard care for patients with hepatocellular carcinoma (HCC) even though it has low antitumor efficacy. Protein neddylation is abnormally activated in many types of human cancer. However, whether dysregulation of neddylation is involved in HCC progression and whether targeting neddylation sensitizes HCC cells to sorafenib need to be ascertained. In the present study, it was demonstrated that high expression of neddylation components, neural precursor cell expressed, developmentally downregulated 8 (NEDD8) and NEDD8-activating enzyme 1 (NAE1), were associated with poor survival of patients with HCC. Inhibition of neddylation by MLN4924, a small-molecule inhibitor of NAE1, significantly inhibited HCC growth, reduced clonogenic survival, increased apoptosis, and decreased migration capacity. Sorafenib alone exhibited minimal anticancer efficacy. However, a combination of sorafenib with MLN4924 at a low concentration significantly enhanced the inhibition of cell proliferation and migration as well as the induction of apoptosis induced by sorafenib. In vivo HCC xenograft mouse models also showed that MLN4924 increased the antitumor efficacy of sorafenib. Mechanistically, MLN4924 enhanced the antitumor activity of sorafenib in HCC cells via upregulation of cullin-RING E3 ubiquitin ligase (CRL)/Skp1-Cullin1-F box (SCF) E3 ubiquitin ligase substrates p21, p27, Deptor and IκBɑ. Taken together, these findings suggest that combination therapy of MLN4924 with sorafenib appears to present an additive effect with a maximal in the treatment of HCC.

E2F1 interactive with BRCA1 pathway induces HCC two different small molecule metabolism or cell cycle regulation via mitochondrion or CD4+T to cytosol

Breast cancer 1 (BRCA1) and E2F transcription factor 1 (E2F1) are related to metabolism and cell cycle regulation. However, the corresponding mechanism is not clear in HCC. High BRCA1 direct pathway was constructed with 11 molecules from E2F1 feedback-interactive network in HCC by GRNInfer based on 39 Pearson mutual positive corelation CC ≥0.25 molecules with E2F1. Integration of GRNInfer with GO, KEGG, BioCarta, GNF_U133A, UNIGENE_EST, Disease, GenMAPP databases by DAVID and MAS 3.0, E2F1 feedback-interactive BRCA1 indirect mitochondrion to cytosol pathway was identified as upstream LAPTM4B activation, feedback UNG, downstream BCAT1-HIST1H2AD-TK1 reflecting protein, and DNA binding with enrichment of small molecule metabolism; The corresponding BRCA1 indirect membrane to cytosol pathway as upstream CCNB2-NUSAP1 activation, feedback TTK-HIST1H2BJ-CENPF, downstream MCM4-TK1 reflecting ATP, and microtubule binding with enrichment of CD4+T-related cell cycle regulation in HCC. Therefore, we propose that E2F1 interactive with BRCA1 pathway induces HCC two different small molecule metabolism or cell cycle regulation via mitochondrion or CD4+T to cytosol. Knowledge analysis demonstrates our E2F1 feedback-interactive BRCA1 pathway wide disease distribution and reflects a novel common one of tumor and cancer.