TRIM15 is a focal adhesion protein that regulates focal adhesion disassembly

Identification of RING E3 pseudoligases in the TRIM protein family

TRIpartite Motif (TRIM) family proteins have diverse roles across a broad variety of cellular functions, which are largely presumed to depend on their ubiquitin E3 ligase activity, conferred by a RING domain. However, recent reports have shown that some TRIMs lack detectable ubiquitination activity in isolation, despite containing a RING domain. Here, we present parallel in cellulo, in vitro, and in silico structure-function analyses of the ubiquitin E3 ligase activity and RING domain structural characteristics of the whole TRIM protein family. In-depth follow-up studies of this comprehensive dataset reveals a number of 'pseudoligases', whose RING domains have structurally diverged at either the homodimerisation or E2~ubiquitin interfaces, thereby disrupting their ability to catalyse ubiquitin transfer. Together, these data raise intriguing open questions regarding the unknown TRIM functions in physiology and disease.

Exploring the role of the disulfidptosis-related gene SLC7A11 in adrenocortical carcinoma: implications for prognosis, immune infiltration, and therapeutic strategies

BACKGROUND

Disulfidptosis and the disulfidptosis-related gene SLC7A11 have recently attracted significant attention for their role in tumorigenesis and tumour management. However, its association with adrenocortical carcinoma (ACC) is rarely discussed.

METHODS

Differential analysis, Cox regression analysis, and survival analysis were used to screen for the hub gene SLC7A11 in the TCGA and GTEx databases and disulfidptosis-related gene sets. Then, we performed an association analysis between SLC7A11 and clinically relevant factors in ACC patients. Univariate and multivariate Cox regression analyses were performed to evaluate the prognostic value of SLC7A11 and clinically relevant factors. Weighted gene coexpression analysis was used to find genes associated with SLC7A11. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses and the LinkedOmics database were used to analyse the functions of SLC7A11-associated genes. The CIBERSORT and Xcell algorithms were used to analyse the relationship between SLC7A11 and immune cell infiltration in ACC. The TISIDB database was applied to search for the correlation between SLC7A11 expression and immune chemokines. In addition, we performed a correlation analysis for SLC7A11 expression and tumour mutational burden and immune checkpoint-related genes and assessed drug sensitivity based on SLC7A11 expression. Immunohistochemistry and RT‒qPCR were used to validate the upregulation of SLC7A11 in the ACC.

RESULTS

SLC7A11 is highly expressed in multiple urological tumours, including ACC. SLC7A11 expression is strongly associated with clinically relevant factors (M-stage and MYL6 expression) in ACC. SLC7A11 and the constructed nomogram can accurately predict ACC patient outcomes. The functions of SLC7A11 and its closely related genes are tightly associated with the occurrence of disulfidptosis in ACC. SLC7A11 expression was tightly associated with various immune cell infiltration disorders in the ACC tumour microenvironment (TME). It was positively correlated with the expression of immune chemokines (CXCL8, CXCL3, and CCL20) and negatively correlated with the expression of immune chemokines (CXCL17 and CCL14). SLC7A11 expression was positively associated with the expression of immune checkpoint genes (NRP1, TNFSF4, TNFRSF9, and CD276) and tumour mutation burden. The expression level of SLC7A11 in ACC patients is closely associated withcthe drug sensitivity.

CONCLUSION

In ACC, high expression of SLC7A11 is associated with migration, invasion, drug sensitivity, immune infiltration disorders, and poor prognosis, and its induction of disulfidptosis is a promising target for the treatment of ACC.

Whole-genome DNA methylation and DNA methylation-based biomarkers in lung squamous cell carcinoma

Exploring early detection methods through comprehensive evaluation of DNA methylation for lung squamous cell carcinoma (LUSC) patients is of great significance. By using different machine learning algorithms for feature selection and model construction based on The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases, five methylation biomarkers in LUSC (along with mapped genes) were identified including cg14823851 (TBX4), cg02772121 (TRIM15), cg10424681 (C6orf201), cg12910906 (ARHGEF4), and cg20181079 (OR4D11), achieving extremely high sensitivity and specificity in distinguishing LUSC from normal samples in independent cohorts. Pyrosequencing assay verified DNA methylation levels, meanwhile qRT-PCR and immunohistochemistry results presented their accordant methylation-related gene expression statuses in paired LUSC and normal lung tissues. The five methylation-based biomarkers proposed in this study have great potential for the diagnosis of LUSC and could guide studies in methylation-regulated tumor development and progression.

TRIM15 and CYLD regulate ERK activation via lysine-63-linked polyubiquitination

The extracellular signal-regulated kinases ERK1 and ERK2 represent the foremost mitogenic pathway in mammalian cells, and their dysregulation drives tumorigenesis and confers therapeutic resistance. ERK1/2 are known to be activated by MAPK/ERK kinase (MEK)-mediated phosphorylation. Here we show that ERK1/2 are also modified by Lys63-linked polyubiquitin chains. We identify the tripartite motif-containing protein TRIM15 as a ubiquitin ligase, and the tumor suppressor CYLD as a deubiquitinase, for ERKs. TRIM15 and CYLD regulate ERK ubiquitination at defined lysine residues via mutually exclusive interactions as well as opposing activities. K63-linked polyubiquitination enhances ERK interaction with and activation by MEK. Down-regulation of TRIM15 inhibits growth of both drug-responsive and -resistant melanomas. Moreover, high TRIM15 expression and low CYLD expression are associated with poor prognosis of melanoma patients. These findings define a role of Lys63-linked polyubiquitination in the ERK signaling pathway and suggest a potential target for cancer therapy.

Knockdown of TRIM15 inhibits the activation of hepatic stellate cells

Liver fibrosis is a global public health problem, and the activation of hepatic stellate cells (HSCs) is the main driving force for liver fibrosis. However, the activation mechanism of HSCs is still not fully understood. In this study, we screened out 854 differentially expressed genes [Log₂ fold change absolute: log2 FC(abs) ≥ 1] in activated LX-2 cells. Subsequently, we performed functional analyses of these differentially expressed genes. Gene Ontology enrichment analysis showed that the target genes were mainly enriched in processes such as positive regulation of cell migration involved in sprouting angiogenesis, negative regulation of keratinocyte proliferation, and nuclear inclusion bodies. Kyoto Encyclopedia of Gene and Genome signaling pathway enrichment analysis revealed that dysregulated genes were involved in signaling pathways such as pantothenate and coenzyme A biosynthesis and riboflavin metabolism. The microarray results were validated by reverse transcription-quantitative polymerase chain reaction, which indicated that the microarray results were reliable and that the tripartite motif containing 15 (TRIM15) had the highest absolute value of Log₂FC. Additionally, the effect of TRIM15 on the proliferation, migration, and activation of LX-2 cells was assessed using overexpression plasmids and siRNA transfections. TRIM15 promoted the proliferation and migration of LX-2 cells and positively regulated the expression of α-smooth muscle actin and type I collagen. Collectively, the data revealed the gene expression profiles of quiescent and activated LX-2 cells and the involvement of TRIM15 in the activation of LX-2 cells. Hereby, TRIM15 could be a novel target of the HSC activation mechanism.

Analysis of TRIM21 Genetic Variants on the Clinicopathologic Characteristics of Patients with Hepatocellular Carcinoma

Tripartite motif 21 (TRIM21) plays an important role in hepatocellular carcinoma (HCC). However, the gene polymorphisms of TRIM21 in HCC is not as well known. In this study, two single nucleotide polymorphisms (SNPs) in the TRIM21 gene, rs4144331, and re915956, were selected to investigate correlations between these SNPs and susceptibility to HCC. Two SNPs of the TRIM21 gene from 1196 controls without cancer and 394 HCC patients were analyzed using real-time polymerase chain reaction. These results were further analyzed to expound the associations between these TRIM21 polymorphisms and the risk of HCC as well as the impact of these SNPs on clinicopathological characteristics of HCC. After adjustment for other covariants, we observed that that younger patients (<65 years) with the TRIM21 rs915956 A allele had a probability of HCC (AOR = 3.153, 95% CI: 1.315–7.516, p = 0.010). Moreover, patients with a smoking habit who carried the T allele of rs4144331 had more probability of HCC (AOR = 2.940, 95% CI: 1.331–6.491, p = 0.008). In addition, we observed that the polymorphic T allele of rs4144331 led to distant metastasis. Thus, our findings suggest that genetic variations in TRIM21 may correlate to HCC and evaluate distant metastasis in patients with HCC.

TRIM21 Polymorphisms are associated with Susceptibility and Clinical Status of Oral Squamous Cell Carcinoma patients

Squamous cell cancer of head and neck (HNSCC) is the sixth most common malignancy worldwide. One of the most common HNSCC types is oral squamous cell carcinoma (OSCC), which is the fifth leading cause of cancer death in Taiwan. Tripartite motif 21 (TRIM21) has been reported to play an important role in different cancer types. We found a correlation between TRIM21 and survival of HNSCC patients, but little information exists about how altered TRIM21 expression contributes to tumorigenesis. Thus, we investigated the combined effect of TRIM21 polymorphisms and exposure to environmental carcinogens on the susceptibility and clinicopathological characteristics of OSCC. Two single-nucleotide polymorphisms (SNPs) of TRIM21 (rs4144331, rs915956) from 1194 healthy controls and 1192 OSCC patients were analyzed by real-time PCR. Among 1632 smokers, TRIM21 polymorphism carriers with the betel-nut chewing habit had a ~4.8-fold greater risk of OSCC than TRIM21 wild-type carriers without the betel-nut chewing habit. After adjusting for other covariants, OSCC patients with G/T at TRIM21 rs4144331 had a high risk for distant metastasis compared with G/G homozygotes. This study is the first to examine the risk factors associated with TRIM21 SNPs in OSCC progression and development. Thus, our findings suggest that this study is the first to examine the risk factors associated with TRIM21 SNPs in OSCC progression and development and suggest that interactions between mutant genes may alter the susceptibility to OSCC.

Cell-cell junctions: structure and regulation in physiology and pathology

Epithelial and endothelial cell-cell contacts are established and maintained by several intercellular junctional complexes. These structurally and biochemically differentiated regions on the plasma membrane primarily include tight junctions (TJs), and anchoring junctions. While the adherens junctions (AJs) provide essential adhesive and mechanical properties, TJs hold the cells together and form a near leak-proof intercellular seal by the fusion of adjacent cell membranes. AJs and TJs play essential roles in vascular permeability. Considering their involvement in several key cellular functions such as barrier formation, proliferation, migration, survival, and differentiation, further research is warranted on the composition and signaling pathways regulating cell-cell junctions to develop novel therapeutics for diseases such as organ injuries. The current review article presents our current state of knowledge on various cell-cell junctions, their molecular composition, and mechanisms regulating their expression and function in endothelial and epithelial cells.

Discriminating Origin Tissues of Tumor Cell Lines by Methylation Signatures and Dys-Methylated Rules

DNA methylation is an essential epigenetic modification for multiple biological processes. DNA methylation in mammals acts as an epigenetic mark of transcriptional repression. Aberrant levels of DNA methylation can be observed in various types of tumor cells. Thus, DNA methylation has attracted considerable attention among researchers to provide new and feasible tumor therapies. Conventional studies considered single-gene methylation or specific loci as biomarkers for tumorigenesis. However, genome-scale methylated modification has not been completely investigated. Thus, we proposed and compared two novel computational approaches based on multiple machine learning algorithms for the qualitative and quantitative analyses of methylation-associated genes and their dys-methylated patterns. This study contributes to the identification of novel effective genes and the establishment of optimal quantitative rules for aberrant methylation distinguishing tumor cells with different origin tissues.

High Expression of TRIM15 Is Associated with Tumor Invasion and Predicts Poor Prognosis in Patients with Gastric Cancer

BACKGROUND

Gastric cancer is the third leading cause of cancer-related mortality worldwide. Most tripartite motif (TRIM) family proteins are known as E3 ubiquitin ligases and considerable previous research has revealed the involvement of TRIM proteins in carcinogenesis. TRIM15 is a protein from the TRIM family and the aim of this study is to investigate the role of TRIM15 in gastric cancer.

METHODS

We conducted immunohistochemical staining to examine TRIM15 expression using samples from Zhongshan Hospital of Fudan University. We also conducted transwell assay as well as western blot by using gastric cancer cells.

RESULTS

The expression of TRIM15 in gastric cancer tissues was higher than normal tissues. Present data demonstrated that high TRIM15 staining intensity had a positive relation to tumor invasion depth (P = 0.007), lymph node metastasis (P = 0.013), distant metastasis (P = 0.031), the tumor-node-metastasis (TNM) staging system (P = 0.002) and shorter overall survival (OS) in gastric cancer patients (P < 0.001). It was also worthwhile mentioning that TRIM15 was an adverse prognostic variable for OS. To gain more insight, we incorporated TRIM15 expression into the tumor-node-metastasis (TNM) staging system and thus established a nomogram. Data derived from the nomogram suggested that fitting TRIM15 expression into the prognostic model exhibited better efficiency for predicting OS in gastric cancer patients. Furthermore, TRIM15 promoted migration, invasion and epithelial-mesenchymal transition of gastric cancer cells.

CONCLUSIONS

Together, TRIM15 expression was found as a specific and independent adverse predictor in gastric cancer patients and the nomogram may contribute to better clinical management.

Interleukin (IL)-22 from IL-20 Subfamily of Cytokines Induces Colonic Epithelial Cell Proliferation Predominantly through ERK1/2 Pathway

The interleukin (IL)-20 subfamily of cytokines consists of IL-19, IL-20, IL-22, IL-24, and IL-26, and the expression of IL-20, IL-22, and IL-24 is reported to be higher in the colon of patients with ulcerative colitis. Although the receptors for these cytokines are highly expressed in the colon epithelium, their effects on epithelial renewal are not clearly understood. This study evaluated the effects of IL-20, IL-22, and IL-24 in epithelial renewal using the LS174T human colon cancer epithelial cell line. LS174T cells were treated with IL-20, IL-22, and IL-24 (25, 50, and 100 ng/mL) and a live-cell imaging system was used to evaluate the effects on cell proliferation. Following treatment, the signaling pathways contributing to cell proliferation were investigated through Western blotting in LS174T cells and downstream transcriptional changes through qRT-PCR in LS174T cells, and RNA-Seq in primary murine intestinal epithelial cells. Our results demonstrated that only IL-22 promoted LS174T cell proliferation, mediated via extracellular-signal-regulated kinase (ERK)1/2-mediated downstream regulation of p90RSK, c-Jun, and transcriptional changes of TRIM15 and STOM. IL-22 also promoted expression of ERK1/2-independent genes such as DDR2, LCN2, and LRG1, which are known to be involved in cell proliferation and migration. This study suggests that IL-22 induces cell proliferation in highly proliferative cells such as intestinal epithelial cells.

Rudhira/BCAS3 couples microtubules and intermediate filaments to promote cell migration for angiogenic remodeling

Blood vessel formation requires endothelial cell (EC) migration that depends on dynamic remodeling of the cytoskeleton. Rudhira/Breast Carcinoma Amplified Sequence 3 (BCAS3) is a cytoskeletal protein essential for EC migration and sprouting angiogenesis during mouse development and is implicated in metastatic disease. Here, we report that Rudhira mediates cytoskeleton organization and dynamics during EC migration. Rudhira binds to both microtubules (MTs) and vimentin intermediate filaments (IFs) and stabilizes MTs. Rudhira depletion impairs cytoskeletal cross-talk, MT stability, and hence focal adhesion disassembly. The BCAS3 domain of Rudhira is necessary and sufficient for MT-IF cross-linking and cell migration. Pharmacologically restoring MT stability rescues gross cytoskeleton organization and angiogenic sprouting in Rudhira-depleted cells. Our study identifies the novel and essential role of Rudhira in cytoskeletal cross-talk and assigns function to the conserved BCAS3 domain. Targeting Rudhira could allow tissue-restricted cytoskeleton modulation to control cell migration and angiogenesis in development and disease.

TRIM15 Exerts Anti-Tumor Effects Through Suppressing Cancer Cell Invasion in Gastric Adenocarcinoma

Backgrounds

Recent studies have shown that some members of the tripartite motif-containing protein (TRIM) family function as important regulators in several tumors. However, the clinical significance of TRIM15 in gastric adenocarcinoma has not been elucidated. In the present study, we aimed to examine the expression pattern of TRIM15 and explore whether the TRIM15 expression is correlated with clinicopathological characteristics of patients with gastric adenocarcinoma.

Material/Methods

The expression pattern of TRIM15 was examined in gastric adenocarcinoma tissues and adjacent normal stomach tissues by using immunohistochemistry staining. The prognostic role of TRIM15 in gastric cancer patients was evaluated by univariate and multivariate analyses. Clinical outcomes were assessed by the Kaplan-Meier analysis and log-rank test. The effects of TRIM15 on cancer cell proliferation and invasion were tested through cellular experiments.

Results

TRIM15 was highly expressed in normal stomach tissues compared to tumor tissues. TCGA database showed that higher TRIM15 RNA transcription indicates poorer overall survival of gastric cancer patients. Besides, low expression of TRIM15 was significantly associated with advanced tumor invasion depth and advanced TNM stage. Moreover, gastric cancer patients with lower KDM5B expression had poorer overall survival, and TRIM15 was identified as an independent prognosis factor according to multivariate analysis. Using the gastric cancer cell lines, we found that overexpression of TRIM15 can inhibits tumor cell invasion.

Conclusions

Our study demonstrated that low expression of TRIM15 in gastric adenocarcinoma tissues was significantly associated with poorer prognosis of patients, indicating the potential of TRIM15 as a novel clinical biomarker and therapeutic target.

TRIM59 Is a Novel Marker of Poor Prognosis and Promotes Malignant Progression of Ovarian Cancer by Inducing Annexin A2 Expression

Ovarian cancer is the fifth common cause of death in woman worldwide. The tripartite motif-containing (TRIM) proteins consist of more than 70 known protein members. Studies have showed that TRIM proteins are involved in cancer and play important roles in cancer cell proliferation, migration, adhesion and metastasis. Recent studies have indicated that TRIM59, as a putative ubiquitin ligase, is up-regulated in some cancers and associated with poor prognosis of gastric cancer. However, the exact roles of TRIM59 in ovarian cancer are still unknown. In this study, we found that TRIM59 expression was increased and positively associated with histological grades (P = 0.000), FIGO stages (P = 0.016), and metastasis (P = 0.027) in ovarian cancer. A integrative data analysis tool revealed that ovarian cancer patients with high TRIM59 expression were correlated with more unfavorable overall and progression-free survival than the rest patients with low TRIM59 expression (P = 0.0024 and P = 7.5×10^-6, respectively). Based on the finding in the clinical data, we performed a series of cell line and animal experiments, and found that TRIM59 knockdown could significantly inhibit the ovarian cancer cell proliferation, clone formation, and invasion in vitro and the ovarian cancer growth of the subcutaneous and orthotopic implantation in vivo. Furthermore, TRIM59 was found to interact with Annexin A2 and induce Annexin A2 expression. Our data imply that TRIM59 can serve as a promising prognostic marker and a potential therapeutic target.

PTPN12/PTP-PEST Regulates Phosphorylation-Dependent Ubiquitination and Stability of Focal Adhesion Substrates in Invasive Glioblastoma Cells

Glioblastoma (GBM) is an invasive brain cancer with tumor cells that disperse from the primary mass, escaping surgical resection and invariably giving rise to lethal recurrent lesions. Here we report that PTP-PEST, a cytoplasmic protein tyrosine phosphatase, controls GBM cell invasion by physically bridging the focal adhesion protein Crk-associated substrate (Cas) to valosin-containing protein (Vcp), an ATP-dependent protein segregase that selectively extracts ubiquitinated proteins from multiprotein complexes and targets them for degradation via the ubiquitin proteasome system. Both Cas and Vcp are substrates for PTP-PEST, with the phosphorylation status of tyrosine 805 (Y805) in Vcp impacting affinity for Cas in focal adhesions and controlling ubiquitination levels and protein stability. Perturbing PTP-PEST-mediated phosphorylation of Cas and Vcp led to alterations in GBM cell-invasive growth in vitro and in preclinical mouse models. Collectively, these data reveal a novel regulatory mechanism involving PTP-PEST, Vcp, and Cas that dynamically balances phosphorylation-dependent ubiquitination of key focal proteins involved in GBM cell invasion.Significance: PTP-PEST balances GBM cell growth and invasion by interacting with the ATP-dependent ubiquitin segregase Vcp/p97 and regulating phosphorylation and stability of the focal adhesion protein p130Cas.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/14/3809/F1.large.jpg Cancer Res; 78(14); 3809-22. ©2018 AACR.

Expression profiling of TRIM protein family in THP1-derived macrophages following TLR stimulation

Activated macrophages play an important role in many inflammatory diseases including septic shock and atherosclerosis. However, the molecular mechanisms limiting macrophage activation are not completely understood. Members of the tripartite motif (TRIM) family have recently emerged as important players in innate immunity and antivirus. Here, we systematically analyzed mRNA expressions of representative TRIM molecules in human THP1-derived macrophages activated by different toll-like receptor (TLR) ligands. Twenty-nine TRIM members were highly induced (>3 fold) by one or more TLR ligands, among which 19 of them belong to TRIM C-IV subgroup. Besides TRIM21, TRIM22 and TRIM38 were shown to be upregulated by TLR3 and TLR4 ligands as previous reported, we identified a novel group of TRIM genes (TRIM14, 15, 31, 34, 43, 48, 49, 51 and 61) that were significantly up-regulated by TLR3 and TLR4 ligands. In contrast, the expression of TRIM59 was down-regulated by TLR3 and TLR4 ligands in both human and mouse macrophages. The alternations of the TRIM proteins were confirmed by Western blot. Finally, overexpression of TRIM59 significantly suppressed LPS-induced macrophage activation, whereas siRNA-mediated knockdown of TRIM59 enhanced LPS-induced macrophage activation. Taken together, the study provided an insight into the TLR ligands-induced expressions of TRIM family in macrophages.

The ubiquitin-proteasome system regulates focal adhesions at the leading edge of migrating cells

Cell migration requires the cyclical assembly and disassembly of focal adhesions. Adhesion induces phosphorylation of focal adhesion proteins, including Cas (Crk-associated substrate/p130Cas/BCAR1). However, Cas phosphorylation stimulates adhesion turnover. This raises the question of how adhesion assembly occurs against opposition from phospho-Cas. Here we show that suppressor of cytokine signaling 6 (SOCS6) and Cullin 5, two components of the CRL5^SOCS6 ubiquitin ligase, inhibit Cas-dependent focal adhesion turnover at the front but not rear of migrating epithelial cells. The front focal adhesions contain phospho-Cas which recruits SOCS6. If SOCS6 cannot access focal adhesions, or if cullins or the proteasome are inhibited, adhesion disassembly is stimulated. This suggests that the localized targeting of phospho-Cas within adhesions by CRL5^SOCS6 and concurrent cullin and proteasome activity provide a negative feedback loop, ensuring that adhesion assembly predominates over disassembly at the leading edge. By this mechanism, ubiquitination provides a new level of spatio-temporal control over cell migration.

DOI:http://dx.doi.org/10.7554/eLife.17440.001

Animal cells can move in the body, for example to heal a wound, by protruding a leading edge forwards, attaching it to the surroundings and then pulling against these new attachments while disassembling the older ones. Mechanical forces regulate the assembly and disassembly of these attachments, known as focal adhesions, and so do signals from outside the cell that are transmitted to the adhesions via specialized proteins. However, it was not clear how the assembly and disassembly of adhesions is coordinated.

CRL5 is a ubiquitin ligase, an enzyme that can mark other proteins for destruction. Cells migrate more quickly if CRL5 is inhibited, and so Teckchandani and Cooper set out to uncover whether CRL5 affects the assembly and disassembly of focal adhesions. The experiments showed that human cells lacking a crucial component of the CRL5 complex, SOCS6, disassemble adhesions faster than normal cells, but only at their leading edge and not at the rear.

Teckchandani and Cooper also found that SOCS6 localizes to the leading edge by binding to a focal adhesion protein called Cas. Shortly after the attachments assemble, the Cas protein becomes tagged with a phosphate group and then acts to promote the adhesion to disassemble. Further experiments indicated that Cas was marked by the CRL5 complex and possibly destroyed while in or very close to the leading edge adhesions, slowing their disassembly.

Together, these findings suggest that by binding Cas, SOCS6 regulates the turnover of adhesions, specifically by inhibiting disassembly and allowing adhesions to grow at the leading edge. Since SOCS6 is not present in adhesions outside of the leading edge, this may help explain how the older adhesions are disassembled. Future studies could next focus on the exact sequence of events that occur in focal adhesions after the CRL5 complex binds to Cas as the cell migrates.

DOI:http://dx.doi.org/10.7554/eLife.17440.002

Mmu-miR-1894-3p Inhibits Cell Proliferation and Migration of Breast Cancer Cells by Targeting Trim46

Breast cancer is the second leading cause of cancer death in women and the presence of metastasis significantly decreases survival. MicroRNAs are involved in tumor progression and the metastatic spreading of breast cancer. Here, we reported that a microRNA, mmu-miR-1894, significantly decreased the lung metastasis of 4TO7 mouse breast cancer cells by 86.7% in mouse models. Mmu-miR-1894-3p was the functional mature form of miR-1894 and significantly decreased the lung metastasis of 4TO7 cells by 90.8% in mouse models. A dual-luciferase reporter assay indicated that mmu-miR-1894-3p directly targeted the tripartite motif containing 46 (Trim46) 3'-untranslated region (UTR) and downregulated the expression of Trim46 in 4TO7 cells. Consistent with the effect of mmu-miR-1894-3p, knockdown of Trim46 inhibited the experimental lung metastasis of 4TO7 cells. Moreover, knockdown of human Trim46 also prohibited the cell proliferation, migration and wound healing of MBA-MD-231 human breast cancer cells. These results suggested that the effect of knockdown of Trim46 alone was sufficient to recapitulate the effect of mmu-miR-1894 on the metastasis of the breast cancer cells in mouse and that Trim46 was involved in the proliferation and migration of mouse and human breast cancer cells.

Downregulation of TRIM21 contributes to hepatocellular carcinoma carcinogenesis and indicates poor prognosis of cancers

The aim of our work is to clarify the clinical implication and functional role of tripartite motif 21 (TRIM21) in hepatocellular carcinoma (HCC). We validated that TRIM21 was downregulated in liver cancer samples by immunohistochemical (IHC) staining. We also demonstrated that its downregulation was associated with several clinicopathologic features such as tumor numbers, T stage, Barcelona Clinic Liver Cancer (BCLC) stage, and Cancer of the Liver Italian Program (CLIP) stage of HCC patients. Importantly, the expression of TRIM21 in tumor samples is significantly correlated with the prognosis of the patients. We further silenced TRIM21 in HCC cell HepG2 and LM3 and confirmed that TRIM21 silencing will promote cancer cell proliferation (CCK-8 assay), colony forming (plate colony-forming assay), migration (transwell assay), and the ability of antiapoptosis (annexin V-FITC/PI staining) in vitro. Then, we predicted gene sets influenced by TRIM21 by using bioinformatic tools. For the first time, we prove that TRIM21 is a potential tumor suppressor in HCC and its low expression indicates poor prognosis. Our findings provide useful insight into the mechanism of HCC origin and progression and offer clues to novel HCC therapies.

TRIM26 functions as a novel tumor suppressor of hepatocellular carcinoma and its downregulation contributes to worse prognosis

Hepatocellular carcinoma (HCC) is the one of the most common malignancies worldwide and its prognosis is extremely poor. Tripartite motif (TRIM) proteins play crucial roles in cancer cell biology but the function of tripartite motif 26 (TRIM26) has not been investigated. We demonstrated that low expression level of TRIM26 in tumor samples was significantly correlated with worse prognosis in HCC patients. We also demonstrated its expression level was associated with several clinicopathologic features such as AFP level and T stage of HCC patients. Furthermore, we validated that TRIM26 was significantly downregulated in HCC tissue compared with normal liver tissue. To further clarify the functional role of TRIM26 in HCC, We confirmed that TRIM26 silencing can promote cancer cell proliferation, colony forming, migration and invasion in vitro with HCC cell lines HepG2 and Bel-7402. Then we utilized bioinformatic tool to predict gene influenced by TRIM26, showing TRIM26 could modulate gene sets about cancer cell metabolism. In conclusion, we proved that TRIM26 is a novel tumor suppressor modulating multiple metabolism-related pathways in HCC. To our best knowledge, this is the first study to investigate the function of TRIM26 in cancer biology. Our findings provide useful insight into the mechanism of HCC origin and progression. Moreover, TRIM26 may represent a novel therapeutic target for HCC.