Tripartite motif-containing 3 (TRIM3) inhibits tumor growth and metastasis of liver cancer

Advances in the antitumor mechanisms of tripartite motif-containing protein 3

The tripartite motif-containing (TRIM) protein family has steadily become a hotspot in tumor-related research. As a member of the E3 ubiquitin ligase family, TRIM is working on many crucial biological processes, including the regulation of tumor cell proliferation, metastasis, apoptosis, and autophagy. Among the diverse TRIM superfamily members, TRIM3 operates via different mechanisms in various types of tumors. This review primarily focuses on the current state of research regarding the antitumor mechanisms of TRIM3 in different cancers. A more in-depth study of TRIM3 may provide new directions for future antitumor treatments. Our review focuses on TRIM3 proteins and cancer. We searched for relevant articles on the mechanisms by which TRIM3 affects tumorigenesis and development from 1997 to 2023 and summarized the latest progress and future directions. Triad-containing motif protein 3 (TRIM3) is an important protein, which plays a key role in the process of tumorigenesis and development. The comprehensive exploration of TRIM3 is anticipated to pave the way for future advancements in antitumor therapy, which is expected to be a new hallmark for cancer detection and a novel target for drug action. TRIM3 is poised to become a significant milestone in cancer detection and a promising focal point for drug intervention. Recent years have witnessed notable progress in research aimed at unraveling the antitumor mechanism of TRIM3, with far-reaching implications for practical tumor diagnosis, treatment protocols, efficacy evaluation, economics, and pharmaceutical utilization.

Tripartite-motif 3 represses ovarian cancer progression by downregulating lactate dehydrogenase A and inhibiting AKT signaling

The E3 ubiquitin ligase Tripartite-motif 3 (TRIM3) is known to play a crucial role in tumor suppression in various tumors through different mechanisms. However, its function and mechanism in ovarian cancer have yet to be elucidated. Our study aims to investigate the expression of TRIM3 in ovarian cancer and evaluate its role in the development of the disease. Our findings revealed a significant decrease in TRIM3 mRNA and protein levels in ovarian cancer tissues and cells when compared to normal ovarian epithelial tissues and cells. Furthermore, we observed a negative correlation between the protein level of TRIM3 and the FIGO stage, as well as a positive correlation with the survival of ovarian cancer patients. Using gain and loss of function experiments, we demonstrated that TRIM3 can inhibit cell proliferation, migration and invasion of the ovarian cancer cells in vitro, as well as suppress tumor growth in vivo. Mechanistic studies showed that TRIM3 interacts with lactate dehydrogenase A, a key enzyme in the glycolytic pathway, through its B-box and coiled-coil domains and induces its ubiquitination and proteasomal degradation, leading to the inhibition of glycolytic ability in ovarian cancer cells. RNA-sequencing analysis revealed significant alterations in the phosphatidylinositol signaling pathways upon TRIM3 overexpression. Additionally, overexpression of TRIM3 inhibited the phosphorylation of AKT. In conclusion, our study demonstrated that TRIM3 exerts a tumor-suppressive effect in ovarian cancer, at least partially, by downregulating LDHA and inhibiting the AKT signaling pathway, and thus leading to the inhibition of glycolysis and limiting the growth of ovarian cancer cells.

TRIM3 inhibits colorectal cancer cell migration and lipid droplet formation by promoting FABP4 degradation

This study is to investigate the regulation of TRIM3/FABP4 on colorectal cancer (CRC) cell migration and lipid metabolism. After transfection of HCT116, LoVo, or SW480 cells, the expression of FABP4, TRIM3, N-cadherin, Vimentin, E-cadherin, and lipid droplet (LD) formation-related genes was measured by qRT-PCR or western blot assays. Wound healing and Transwell assays were applied to detect CRC cell migration and invasion abilities. The levels of triglyceride (TG) and total cholesterol (TC) were measured and the formation of LDs was observed. Additionally, the relationship between FABP4 and TRIM3 was confirmed by Co-IP and ubiquitination assays. Furthermore, a liver metastasis model of CRC was established to explore the effect of FABP4 on CRC tumor metastasis in vivo. FABP4 was upregulated in CRC cells. Downregulation of FABP4 or upregulation of TRIM3 resulted in repressed cell migration and invasion, decreased TG and TC levels, and reduced numbers of LDs. In nude mice, knockdown of FABP4 reduced metastatic nodules in the liver. Mechanistically, TRIM3 combined FABP4 and decreased its protein expression by ubiquitination. Overexpressed FABP4 reversed the influence of TRIM3 upregulation on CRC cell migration and LD formation. In conclusion, underexpressed TRIM3 suppressed FABP4 ubiquitination and accelerated CRC cell migration and LD formation.

Deciphering roles of TRIMs as promising targets in hepatocellular carcinoma: current advances and future directions

Tripartite motif (TRIM) family is assigned to RING-finger-containing ligases harboring the largest number of proteins in E3 ubiquitin ligating enzymes. E3 ubiquitin ligases target the specific substrate for proteasomal degradation via the ubiquitin-proteasome system (UPS), which seems to be a more effective and direct strategy for tumor therapy. Recent advances have demonstrated that TRIM genes associate with the occurrence and progression of hepatocellular carcinoma (HCC). TRIMs trigger or inhibit multiple biological activities like proliferation, apoptosis, metastasis, ferroptosis and autophagy in HCC dependent on its highly conserved yet diverse structures. Remarkably, autophagy is another proteolytic pathway for intracellular protein degradation and TRIM proteins may help to delineate the interaction between the two proteolytic systems. In depth research on the precise molecular mechanisms of TRIM family will allow for targeting TRIM in HCC treatment. We also highlight several potential directions warranted further development associated with TRIM family to provide bright insight into its translational values in hepatocellular carcinoma.

Dual roles of TRIM3 in colorectal cancer by retaining p53 in the cytoplasm to decrease its nuclear expression

Colorectal cancer is a very heterogeneous disease caused by the interaction of genetic and environmental factors. P53, as a frequent mutation gene, plays a critical role in the adenoma-carcinoma transition during the tumorous pathological process. Our team discovered TRIM3 as a tumor-associated gene in CRC by high-content screening techniques. TRIM3 demonstrated both tumor-suppressive and tumorigenic features in cell experiments dependent on the cell status of wild or mutant p53. TRIM3 could directly interact with the C terminus of p53 (residues 320 to 393), a common segment of wtp53 and mutp53. Moreover, TRIM3 could exert different neoplastic features by retaining p53 in the cytoplasm to decrease its nuclear expression in a wtp53 or mutp53-dependent pathway. Chemotherapy resistance develops in nearly all patients with advanced CRC and seriously limits the therapeutic efficacies of anticancer drugs. TRIM3 could reverse the chemotherapy resistance of oxaliplatin in mutp53 CRC cells by degradation of mutp53 in the nuclei to downregulate the multidrug resistance gene. Therefore, TRIM3 could be a potential therapeutic strategy to improve the survival of CRC patients with mutp53.

Overexpression of ST7-AS1 Enhances Apoptosis and Inhibits Proliferation of Papillary Thyroid Carcinoma Cells Via microRNA-181b-5p-Dependent Inhibition Tripartite Motif Containing 3

Long non-coding RNAs (lncRNAs) are of great significance in the pathogenesis and progression of papillary thyroid carcinoma (PTC). LncRNA tumorigenicity 7 antisense RNA 1 (ST7-AS1) is a newly identified lncRNA serving as an oncogene or tumor suppressor in different tumors; however, the role of ST7-AS1 in PTC remains completely unknown. In this study, ST7-AS1 was mainly distributed in the cytoplasm of PTC cells and presented reduced expression in THCA tumors and PTC cell lines. Functional experiments revealed that overexpressed ST7-AS1 inhibited the viability and proliferation of PTC cells, whereas accelerated the apoptosis of PTC cells. The expression of miR-181b-5p was upregulated and it bound with ST7-AS1 in PTC cells. Moreover, TRIM3 exhibited downregulated expression level in PTC cells and ST7-AS1 elevated TRIM3 expression via harboring miR-181b-5p. Rescue experiments illuminated that knockdown of TRIM3 reversed ST7-AS1 overexpression-induced promotion on PTC cell proliferation and suppression on PTC cell apoptosis. Overall, overexpression of ST7-AS1 enhances apoptosis and represses proliferation of PTC cells via targeting the miR-181b-5p/TRIM3 axis, which may help broaden the horizon and establish the foundation to develop therapeutic strategies for PTC in the future.

Tripartite motif protein 6 promotes hepatocellular carcinoma progression via multiple pathways

Background/aim

Hepatocellular carcinoma (HCC) ranks among the most prevalent malignancies worldwide and the third leading cause of cancer-related death. The TRIM (tripartite motif-containing) protein family members had been reported to be involved in carcinogenesis and tumor progression. Here we aimed to explore the expression profile of TRIM6 in HCC and investigate its clinical significance as well as underlying mechanisms.

Materials and methods

We retrospectively enrolled 138 HCC patients that underwent surgical resection in our hospital and tested protein expression level of TRIM6 through immunohistochemical staining. The correlation between TRIM6 and patients' characteristics was assessed by Chi-square test. Log-rank test and Cox hazard regression test were conducted for univariate and multivariate survival analyses, respectively. Two human HCC cell lines, Huh7 and Hep3B, were subjected for knockdown and overexpression assays, followed by phonotype tests including proliferation and invasion. Nude mice were used to generate xenograft model to validate our findings in vivo.

Results

TRIM6 was highly expressed in HCC specimen compared to nontumorous liver tissues. Higher TRIM6 expression was correlated with larger tumor size, later tumor stage, and worse prognosis. According to the cellular experiments, TRIM6-knockdown resulted in decreased expression of cyclin B1, c-Myc, Snail, MMP2, and VEGF-A. Consistently, TRIM6-knockdown led to impaired HCC proliferation, invasion, and angiogenesis. In contrast, TRIM6 overexpression showed opposite effects. Finally, the oncogenic role of TRIM6 in HCC was validated by in vivo mice experiments.

Conclusion

TRIM6 can serve as a novel prognostic factor for HCC, which functions by multiple signaling pathways.

TRIM3 and TRIM16 as potential tumor suppressors in breast cancer patients

Objective

Breast cancer is the leading cause of death among women in many countries. Numerous factors serve as oncogenes or tumor suppressors in breast cancer. The large family of Tripartite-motif (TRIM) proteins with ~ 80 members has drawn attention for their role in cancer. TRIM3 and TRIM16 have shown suppressive activity in different cancers. This study aimed to evaluate the expression of TRIM3 and TRIM16 in cancerous and normal breast samples and to investigate their association with different clinical and pathological parameters.

Results

qRT-PCR was utilized to determine the gene expression of TRIM3 and TRIM16. The expression of TRIM3 and TRIM16 genes in tumor samples were significantly reduced to 0.45 and 0.29 fold, respectively. TRIM3 and TRIM16 genes expression were both positively correlated with the invasion of breast cancer. TRIM3 gene expression was associated with tumors’ histological grade. However, no significant association was found between the expression of the genes and tumor size, stage and necrosis. The expression of TRIM3 and TRIM16 are significantly reduced in breast cancer tissues. Besides, the expression of both TRIM3 and TRIM16 genes significantly plummet in lymphatic/vascular and perineural invasive samples. Hence, we suggest a potential tumor suppressor role for TRIM3 and TRIM16 in breast cancer.

TRIM proteins in hepatocellular carcinoma

The tripartite motif (TRIM) protein family is a highly conserved group of E3 ligases with 77 members known in the human, most of which consist of a RING-finger domain, one or two B-box domains, and a coiled-coil domain. Generally, TRIM proteins function as E3 ligases to facilitate specific proteasomal degradation of target proteins. In addition, E3 ligase independent functions of TRIM protein were also reported. In hepatocellular carcinoma, expressions of TRIM proteins are both regulated by genetic and epigenetic mechanisms. TRIM proteins regulate multiple biological activities and signaling cascades. And TRIM proteins influence hallmarks of HCC. This review systematically demonstrates the versatile roles of TRIM proteins in HCC and helps us better understand the molecular mechanism of the development and progression of HCC.

Role of Tripartite Motif-Containing 3 Protein (TRIM3) in Rheumatoid Arthritis and Its Mechanism

Aim: To discuss TRIM3’s effects and relative mechanisms in RA development. Materials and methods: Using FLS as research object in our study. Present study divided into two steps, first step, discussing TRIM3 depressing effects in normal FLS cell; next, using IL-1β stimulating to make RA cell model, TRIM3 overexpression in RA model to observe cell biological activities. Measuring IL-6 and TNF-α levels by ELISA kit; evaluating cell proliferation by MTT and EdU assay; relative proteins including TRIM3, TAB2 and NF-κB(p65) proteins expression using WB method. Results: With TRIM3 knockdown, FLS cell proliferation were significantly increased with IL-6, TNF-α levels significantly up-regulation (P < 0.001, respectively). Meanwhile, TAB2 protein expression significantly depressing and NF-κB(p65) protein significantly increasing; those were similar as IL-1β stimulating RA cell model in FLS cell line. In RA cell model, transfection TRIM3 in FLS cell, the cell proliferation was significantly depressed with IL-1β, TNF-α levels depressing, and TAB2 protein expression significantly increasing and NF-κB(p65) protein significantly depressing. Conclusion: TRIM3 knockdown might be a result to RA development; with TRIM3 overexpression, RA induced FLS hyperproliferation significantly improved with TAB2 up-regulation and NF-κB(p65) down-regulation in vitro.

TRIM3 facilitates estrogen signaling and modulates breast cancer cell progression

BACKGROUND

Breast cancer is the most common cancer in women worldwide. More than 70% of breast cancers are estrogen receptor (ER) alpha positive. Compared with ER alpha-negative breast cancer, which is more aggressive and has a shorter survival time, ER alpha-positive breast cancer could benefit from endocrine therapy. Selective estrogen receptor modulators, such as tamoxifen, are widely used in endocrine therapy. Approximately half of ER alpha-positive breast cancer patients will eventually develop endocrine resistance, making it a major clinical challenge in therapy. Thus, decoding the throughput of estrogen signaling, including the control of ER alpha expression and stability, is critical for the improvement of breast cancer therapeutics.

METHODS

TRIM3 and ER alpha protein expression levels were measured by western blotting, while the mRNA levels of ER alpha target genes were measured by RT-PCR. A CCK-8 assay was used to measure cell viability. RNA sequencing data were analyzed by Ingenuity Pathway Analysis. Identification of ER alpha signaling activity was accomplished with luciferase assays, RT-PCR and western blotting. Protein stability assays and ubiquitin assays were used to detect ER alpha protein degradation. Ubiquitin-based immunoprecipitation assays were used to detect the specific ubiquitination modification on the ER alpha protein.

RESULTS

In our current study, we found that TRIM3, an E3 ligase, can promote ER alpha signaling activity and breast cancer progression. TRIM3 depletion inhibits breast cancer cell proliferation and migration, while unbiased RNA sequencing data indicated that TRIM3 is required for the activity of estrogen signaling on the -genome-wide scale. The immunoprecipitation assays indicated that TRIM3 associates with ER alpha and promotes its stability, possibly by inducing K63-linked polyubiquitination of ER alpha. In conclusion, our data implicate a nongenomic mechanism by which TRIM3 stabilizes the ER alpha protein to control ER alpha target gene expression linked to breast cancer progression.

CONCLUSION

Our study provides a novel posttranslational mechanism in estrogen signaling. Modulation of TRIM3 expression or function could be an interesting approach for breast cancer treatment. Video abstract.

Comprehensive profiling of the TRIpartite motif family to identify pivot genes in hepatocellular carcinoma

INTRODUCTION

TRIpartite motif (TRIM) proteins are important members of the Really Interesting New Gene-finger-containing E3 ubiquitin-conjugating enzyme and are involved in the progression of hepatocellular carcinoma (HCC). However, the diverse expression patterns of TRIMs and their roles in prognosis and immune infiltrates in HCC have yet to be analyzed.

MATERIALS

Combined with previous research, we used an Oncomine database and the Human Protein Atlas to compare TRIM family genes' transcriptional levels between tumor samples and normal liver tissues, as verified by the Gene Expression Profiling Interactive Analysis database. We investigated the patient survival data of TRIMs from the Kaplan-Meier plotter database. Clinicopathologic characteristics associations and potential diagnostic and prognostic values were validated with clinical and expressional data collected from the cancer genome atlas.

RESULTS

We identified TRIM28, TRIM37, TRIM45, and TRIM59 as high-priority members of the TRIMs family that modulates HCC. Low expression of TRIM28 was associated with shorter overall survival (OS) than high expression (log-rank p = 0.009). The same trend was identified for TRIM37 (p = 0.001), TRIM45 (p = 0.013), and TRIM59 (p = 0.011). Multivariate analysis indicated that the level of TRIM37 was a significant independent prognostic factor for both OS (p = 0.043) and progression-free interval (p = 0.044). We performed expression and mutation analysis and functional pathways and tumor immune infiltration analysis of the changes in TRIM factors.

CONCLUSION

These data suggested that TRIM28, TRIM37, TRIM45, and TRIM59 could serve as efficient prognostic biomarkers and therapeutic targets in HCC.

Comprehensive Analysis of the Prognostic Values of the TRIM Family in Hepatocellular Carcinoma

Background

Accumulating studies have demonstrated the abnormal expressions and prognostic values of certain members of the tripartite motif (TRIM) family in diverse cancers. However, comprehensive prognostic values of the TRIM family in hepatocellular carcinoma (HCC) are yet to be clearly defined.

Methods

The prognostic values of the TRIM family were evaluated by survival analysis and univariate Cox regression analysis based on gene expression data and clinical data of HCC from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. The expression profiles, protein–protein interaction among the TRIM family, prediction of transcription factors (TFs) or miRNAs, genetic alterations, correlations with the hallmarks of cancer and immune infiltrates, and pathway enrichment analysis were explored by multiple public databases. Further, a TRIM family gene-based signature for predicting overall survival (OS) in HCC was built by using the least absolute shrinkage and selection operator (LASSO) regression. TCGA–Liver Hepatocellular Carcinoma (LIHC) cohort was used as the training set, and GSE76427 was used for external validation. Time-dependent receiver operating characteristic (ROC) and survival analysis were used to estimate the signature. Finally, a nomogram combining the TRIM family risk score and clinical parameters was established.

Results

High expressions of TRIM family members including TRIM3, TRIM5, MID1, TRIM21, TRIM27, TRIM32, TRIM44, TRIM47, and TRIM72 were significantly associated with HCC patients’ poor OS. A novel TRIM family gene-based signature (including TRIM5, MID1, TRIM21, TRIM32, TRIM44, and TRIM47) was built for OS prediction in HCC. ROC curves suggested the signature’s good performance in OS prediction. HCC patients in the high-risk group had poorer OS than the low-risk patients based on the signature. A nomogram integrating the TRIM family risk score, age, and TNM stage was established. The ROC curves suggested that the signature presented better discrimination than the similar model without the TRIM family risk score.

Conclusion

Our study identified the potential application values of the TRIM family for outcome prediction in HCC.

Tripartite motif-containing 3 (TRIM3) enhances ER signaling and confers tamoxifen resistance in breast cancer

Tamoxifen resistance remains a clinical problem in estrogen receptor (ER)-positive breast cancer. SUMOylation of ERα enhances ERα-induced transcription activity. Tripartite motif-containing (TRIM) proteins are a new class of SUMO E3 ligases, which regulate the SUMOylation of proteins. However, the precise molecular mechanism and function of TRIM3 in SUMOylation and the response to tamoxifen remain unclear. In the present study, we observed that TRIM3 was dramatically overexpressed in breast cancer, which correlated with tamoxifen resistance. Furthermore, TRIM3 overexpression significantly correlated with poor survival of patients with ER⁺ breast cancer treated with tamoxifen. TRIM3 overexpression conferred cell survival and tumorigenesis, whereas knocking down of TRIM3 reduced these capabilities. Moreover, TRIM3, as a ubiquitin carrier protein 9 (UBC9) binding protein, promoted SUMO modification of estrogen receptor 1 (ESR1) and activated the ER pathway. Silencing UBC9 abolished the function of TRIM3 in regulating tamoxifen resistance. These results suggest TRIM3 as a novel biomarker for breast cancer therapy, indicating that inhibiting TRIM3 combined with tamoxifen might provide a potential treatment for breast cancer.

A network approach reveals driver genes associated with survival of patients with triple-negative breast cancer

We aimed to identify triple-negative breast cancer (TNBC) drivers that regulate survival time as predictive signatures that improve TNBC prognostication. Breast cancer (BrCa) transcriptomic tumor biopsies were analyzed, identifying network communities enriched with TNBC-specific differentially expressed genes (DEGs) and correlated strongly to TNBC status. Two anticorrelated modules correlated strongly to TNBC subtype and survival. Querying module-specific hubs and DEGs revealed transcriptional changes associated with high survival. Transcripts were nominated as biomarkers and tested as combinatoric ratios using receiver operator characteristic (ROC) analysis to assess survival prediction. ROC test rounds integrated genes with established interactions to hubs and DEGs of key modules, improving prediction. Finally, we tested whether integration of literature-derived genes for implicated hallmark cancer processes could improve prediction of survival. Complementary coexpression, differential expression, genetic interaction, and survival stratification integrated by ROC optimization uncovered a panel of "linchpin survival genes" predictive of patient survival, representing gene interactions in hallmark cancer processes.

TRIM3 inhibits P53 signaling in breast cancer cells

BACKGROUND

Beast cancer is the most common women cancer worldwide, while two third of them are ER alpha positive breast cancer. Among the ER alpha positive breast cancer, about 80% are P53 wild type, indicating the potential tumor suppression role in ER alpha positive breast cancer. Since P53 is an important safeguard to inhibit cell malignant transformation, reactivating P53 signaling could a plausible approach to treat breast cancer.

METHODS

TRIM3 protein levels were measured by western blot, while the P53 classical target genes were measured by real-time PCR. WST1 assay were used to measure cell proliferation, while cleaved caspase-3 was used to detect cell apoptosis. Protein stability and ubiquitin assay were used to detect the P53 protein ubiquitin and stability. The immuno-precipitation assays were used to detect the protein interactions. Immuno-staining was used to detect the protein localization of P53 and TRIM3, while the ubiquitin-based immuno-precipitation assays were used to detect the specific ubiquitination manner of P53.

RESULTS

In our study, we identified TRIM3 as an endogenous inhibitor for P53 signaling. TRIM3 depletion inhibited breast cancer cell proliferation and promoted apoptosis. In addition, TRIM3 depletion increased P53 protein level in breast cancer cell. Further investigation showed that TRIM3 could associate with P53 and promote P53 K48-linked ubiquitination and degradation.

CONCLUSION

Our study identified a novel post-translational modification mechanism between TRIM3 and P53. TRIM3 depletion or blockage could be a promising strategy to rescue P53 signaling and inhibit breast cancer progression.

Ubiquitination of TLR3 by TRIM3 signals its ESCRT-mediated trafficking to the endolysosomes for innate antiviral response

Trafficking of toll-like receptor 3 (TLR3) from the endoplasmic reticulum (ER) to endolysosomes and its subsequent proteolytic cleavage are required for it to sense viral double-stranded RNA (dsRNA) and trigger antiviral response, yet the underlying mechanisms remain enigmatic. We show that the E3 ubiquitin ligase TRIM3 is mainly located in the Golgi apparatus and transported to the early endosomes upon stimulation with the dsRNA analog poly(I:C). TRIM3 mediates K63-linked polyubiquitination of TLR3 at K831, which is enhanced following poly(I:C) stimulation. The polyubiquitinated TLR3 is recognized and sorted by the ESCRT (endosomal sorting complex required for transport) complexes to endolysosomes. Deficiency of TRIM3 impairs TLR3 trafficking from the Golgi apparatus to endosomes and its subsequent activation. Trim3 ^-/- cells and mice express lower levels of antiviral genes and show lower levels of inflammatory response following poly(I:C) but not lipopolysaccharide (LPS) stimulation. These findings suggest that TRIM3-mediated polyubiquitination of TLR3 represents a feedback-positive regulatory mechanism for TLR3-mediated innate immune and inflammatory responses.

[Musashi-1 positively regulates growth and proliferation of hepatoma cells in vitro]

OBJECTIVE

To investigate the regulatory role of Musashi-1 (MSI1) in the proliferation and growth of hepatocellular carcinoma (HCC) cells.

METHODS

We examined the expression of MSI1 in HCC and paired adjacent tissues from 24 patients using immunohistochemistry and Western blotting. A MSI1-expressing vector was constructed and stably transfected into HepG2 cells, and short hairpin RNAs (shRNAs) that targeted MSI1 mRNA were ligated into the vector and stably transfected in Huh7 cells. The effects of MSI1 overexpression and silencing on the proliferation, viability and cell cycle of HepG2 cells were investigated using flow cytometry or MTT assay. The expressions of PCNA, cyclin D1, APC and β-catenin in the HCC cells were detected with Western blotting.

RESULTS

MSI1 expression was significantly up-regulated in HCC tissues as compared with that in the adjacent tissues. Overexpression of MSI1 in HepG2 cells resulted in significantly enhanced cell growth (P < 0.01) and significantly reduced G0/G1 phase cells from (58.42±3.18)% to (40.67±1.22)% and increased S phase cells from (28.51± 1.93)% to (40.06±1.92)% (P < 0.01), causing also increases in the expressions of PCNA and Cyclin D1. Knockdown of MSI1 in Huh7 cells obviously inhibited the cell growth and caused cell cycle arrest at the G1/S phase (P < 0.01) with reduced protein expressions of PCNA and cyclin D1. Overexpression of MSI1 in HepG2 cells also down-regulated the expression of APC and up-regulated the expression of β-catenin protein, while MSI1 knockdown caused reverse changes in Huh7 cells.

CONCLUSIONS

MSI1 promotes the progression of HCC through positive modulation of cell growth and cell cycle via the Wnt/β-catenin pathway.

The role of TRIM family proteins in the regulation of cancer stem cell self-renewal

The tripartite-motif (TRIM) family of proteins represents one of the largest classes of putative single protein RING-finger E3 ubiquitin ligases. The members of this family are characterized by an N-terminal TRIM motif containing one RING-finger domain, one or two zinc-finger domains called B boxes (B1 box and B2 box), and a coiled-coil region. The TRIM motif can be found in isolation or in combination with a variety of C-terminal domains, and based on C-terminus, TRIM proteins are classified into 11 distinct groups. Because of the complex nature of TRIM proteins, they are implicated in a variety of cellular functions and biological processes, including regulation of cell proliferation, cell division and developmental processes, cancer transformation, regulation of cell metabolism, autophagocytosis, modification of chromatin status, regulation of gene transcription, post-translational modifications, and interactions with pathogens. Here, we demonstrate the specific activities of TRIM family proteins that contribute to the cancer stem cell phenotype. A growing body of evidence demonstrates that several TRIM members guarantee the acquisition of stem cell properties and the ability to sustain stem-like phenotype by cancer cells using distinct mechanisms. For other members, further work is needed to understand their full contribution to stem cell self-renewal. Identification of TRIM proteins that possess the potential to serve as therapeutic targets may result in the development of new therapeutic strategies. Finally, these strategies may result in the disruption of the machinery of stemness acquisition, which may prevent tumor growth, progression, and overcome the resistance to anticancer therapies.

BNIPL‑2 expression is correlated with the prognosis and regulates the proliferation of colorectal cancer through CD44

Colorectal cancer (CRC) currently leads to many deaths worldwide. The regulatory mechanism, however, remains largely unclear. In the present study, bioinformatics methods were used to identify genes associated with CRC prognosis and to detect the molecular signals regulating the cell cycle in two CRC cell lines. It was revealed that BNIPL-2 expression was higher in CRC tissues than in adjacent tissue samples. Upregulation of BNIPL-2 was correlated with poor prognosis and the adverse malignant stages T and M. BNIPL-2 was also associated with signaling pathways involved in cancer cell growth. BNIPL-2 overexpression promoted cell proliferation and increased the proportion of cells in the G2/M phase. Knockdown of BNIPL-2 inhibited cell proliferation. CD44 was regulated by BNIPL-2 and promoted cell proliferation. Downregulation of CD44 suppressed cell proliferation and rescued the cell proliferation promoted by BNIPL-2. Overexpression of CD44 restored the cell proliferation suppressed by BNIPL-2 knockdown. The present study not only suggested that BNIPL-2 may be a potential biomarker of CRC but also indicated that BNIPL-2 regulates CRC cancer proliferation via CD44, which could be a diagnostic and clinical treatment target.

miR-454-3p promotes proliferation and induces apoptosis in human cervical cancer cells by targeting TRIM3

Abnormally expressed microRNAs have been demonstrated related to the development and progression of cervical cancer. However, the molecular mechanisms remain largely unkown. Here, we aimed to demonstrate the exact role of miR-454-3p in cervical cancer. Depletion of miR-454-3p in cervical cancer cells resulted in inhibition of cell growth and promotion of cell apoptosis. Bioinformatics analysis predicted that tripartite motif-containing 3 (TRIM3), a tumor suppressor gene in cervical cancer, is a promising target of miR-454-3p. Dual-luciferase reporter gene assay revealed that miR-454-3p directly target TIRM3 by binding to the 3'UTR of TIRM3. In cervical cancer cells (C-33A and SiHa) with endogenous low TRIM3 expression, decreased expression of miR-454-3p significantly elevated TRIM3 expression. In the cervical cancer cell (HeLa) with endogenous high TRIM3 expression, increased expression of miR-454-3p obviously inhibited TRIM3 expression and then manipulating cell growth and apoptosis, down-regulating the expression of P53 and cleaved caspase-3 via P38 MAPK signaling. Taken together, these findings demonstrated miR-454-3p as a cancer promoter by targeting TRIM3 in human cervical cancer.

miR-4513 promotes breast cancer progression through targeting TRIM3

The biological function of microRNA-4513 (miR-4513) in human cancers is emerging. However, it remains unknown whether miR-4513 has a role in breast cancer (BC). In this study, we analyzed the expression of miR-4513 and tripartite motif containing 3 (TRIM3) in BC cell lines. The biological roles of miR-4513 and TRIM3 in BC were analyzed by cell counting kit-8 assay, colony formation assay, wound healing assay, and transwell invasion assay. The effects of miR-4513 or TRIM3 expression on the overall survival of BC patients were analyzed at Kaplan-Meier plotter website. We found miR-4513 expression was upregulated, whereas TRIM3 expression was downregulated in BC cell lines. Importantly, high miR-4513 or low TRIM3 expression was revealed as predictors for poorer overall survival of BC patients. Luciferase activity assay and western blot assay revealed TRIM3 was a direct target of miR-4513. Moreover, we showed miR-4513 was able to regulate BC cell proliferation, colony formation, cell migration, and cell invasion through regulating TRIM3. Taken together, our results suggested miR-4513 functions as an oncogene in the progression of BC and, therefore, miR-4513 may be validated as a potential therapeutic target in the future.