Overexpression of TRIM25 in Lung Cancer Regulates Tumor Cell Progression

Intricate confrontation: Research progress and application potential of TRIM family proteins in tumor immune escape

BACKGROUND

Tripartite motif (TRIM) family proteins have more than 80 members and are widely found in various eukaryotic cells. Most TRIM family proteins participate in the ubiquitin-proteasome degradation system as E3-ubiquitin ligases; therefore, they play pivotal regulatory roles in the occurrence and development of tumors, including tumor immune escape. Due to the diversity of functional domains of TRIM family proteins, they can extensively participate in multiple signaling pathways of tumor immune escape through different substrates. In current research and clinical contexts, immune escape has become an urgent problem. The extensive participation of TRIM family proteins in curing tumors or preventing postoperative recurrence and metastasis makes them promising targets.

AIM OF REVIEW

The aim of the review is to make up for the gap in the current research on TRIM family proteins and tumor immune escape and propose future development directions according to the current progress and problems.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This up-to-date review summarizes the characteristics and biological functions of TRIM family proteins, discusses the mechanisms of TRIM family proteins involved in tumor immune escape, and highlights the specific mechanism from the level of structure-function-molecule-pathway-phenotype, including mechanisms at the level of protein domains and functions, at the level of molecules and signaling pathways, and at the level of cells and microenvironments. We also discuss the application potential of TRIM family proteins in tumor immunotherapy, such as possible treatment strategies for combination targeting TRIM family protein drugs and checkpoint inhibitors for improving cancer treatment.

TRIM25-mediated ubiquitination of G3BP1 regulates the proliferation and migration of human neuroblastoma cells

Neuroblastoma is one of the most severe malignant tumors and accounts for substantial cancer-related mortality in children. Ras-GTPase-activating protein SH3 domain-binding protein 1 (G3BP1) is highly expressed in various cancers and acts as an important biomarker of poor prognosis. The ablation of G3BP1 inhibited the proliferation and migration of human SHSY5Y cells. Because of its important role in neuroblastoma, the regulation of G3BP1 protein homeostasis was probed. TRIM25, which belongs to the tripartite motif (TRIM) family of proteins, was identified as an interacting partner for G3BP1 using the yeast two-hybrid (Y2H) method. TRIM25 mediates the ubiquitination of G3BP1 at multiple sites and stabilizes its protein level. Then, our study found that TRIM25 knockdown also inhibited the proliferation and migration of neuroblastoma cells. The TRIM25 and G3BP1 double knockdown SHSY5Y cell line was generated, and double knockdown cells exhibited lower proliferation and migration ability than cells with only TRIM25 or G3BP1 knockdown. Further study demonstrated that TRIM25 promotes the proliferation and migration of neuroblastoma cells in a G3BP1-dependent manner. Tumor xenograft assays indicated that the ablation of TRIM25 and G3BP1 synergistically suppressed the tumorigenicity of neuroblastoma cells in nude mice, and TRIM25 promoted the tumorigenicity of G3BP1 intact SHSY5Y cells but not G3BP1 knockout cells. Thus, TRIM25 and G3BP1, two oncogenic genes, are suggested as potential therapeutic targets for neuroblastoma.

Identification of peptide binding sequence of TRIM25 on 14-3-3σ by bioinformatics and biophysical techniques

14-3-3σ protein is one of the seven isoforms from the highly conserved eukaryotic 14-3-3 protein family. Downregulation of 14-3-3σ expression has been observed in various tumors. TRIM25 is responsible for the proteolytic degradation of 14-3-3σ, in which abrogation of TRIM25 suppressed tumor growth through 14-3-3σ upregulation. However, to date, the exact 14-3-3σ interacting residues of TRIM25 have yet to be resolved. Thus, this study attempts to identify the peptide binding sequence of TRIM25 on 14-3-3σ via both bioinformatics and biophysical techniques. Multiple sequence alignment of the CC domain of TRIM25 revealed five potential peptide binding sequences (Peptide 1-5). Nuclear magnetic resonance (NMR) assay (1H CPMG) identified Peptide 1 as an important sequence for binding to 14-3-3σ. Competition NMR assay suggested that Peptide 1 binds to the amphipathic pocket of 14-3-3σ with an estimated KD of 116.4 µM by isothermal titration calorimetry. Further in silico docking and molecular dynamics simulations studies proposed that Peptide 1 is likely to interact with Lys49, Arg56, Arg129, and Tyr130 residues at the amphipathic pocket of 14-3-3σ. These results suggest that Peptide 1 may serve as a biological probe or a template to design inhibitors of TRIM25-14-3-3σ interaction as a potentially novel class of anticancer agents.Communicated by Ramaswamy H. Sarma.

Small Nucleolar RNA and C/D Box 15B Regulate the TRIM25/P53 Complex to Promote the Development of Endometrial Cancer

Background

Endometrial cancer is associated with a high mortality rate, which warrants the identification of novel diagnostic markers and therapeutic targets. The aim of this study is to evaluate the role of SNORD15B in the development of endometrial cancer and explore the potential underlying mechanisms.

Methods

Bioinformatics was used to analyze the expression level and prognostic relevance of SNORD15B in endometrial cancer. The Ishikawa and HEC-1B cells were respectively transfected with SNORD15B expression plasmid and an antisense oligonucleotide, or the corresponding empty vector and a nonspecific sequence. The malignant phenotype of the suitably transfected cells was assessed by standard in vitro functional assays and the establishment of in vivo xenografts. The expression levels of the specific markers were analyzed with RT-qPCR and western blotting. The subcellular localization of P53 was determined by analyzing the nuclear and cytoplasmic fractions. RIP, Co-IP, and immunohistochemistry were performed as per standard protocols.

Results

SNORD15B was overexpressed in the endometrial cancer tissues and correlated to a poor prognosis. Ectopic expression of SNORD15B in Ishikawa cells inhibited apoptosis, increased the proliferation, invasion, and migration in vitro, and enhanced their tumorigenicity in vivo. SNORD15B overexpression also upregulated TRIM25 and accelerated P53 accumulation in the cytoplasm of the endometrial cancer cells.

Conclusion

SNORD15B functions as an oncogene in endometrial cancer by targeting the TRIM25/P53 complex and blocking the nuclear translocation of P53.

TRIM25: A central factor in breast cancer

TRIM25 is emerging as a central factor in breast cancer due to its regulation and function. In particular, it has been shown that: (1) Estrogens modulate TRIM25 gene expression; (2) TRIM25 has activity as an E3-ligase enzyme for ubiquitin; and (3) TRIM25 is also an E3 ligase for interferon-stimulated gene 15 protein in the ISGylation system. Consequently, the proteome of mammary tissue is affected by TRIM25-associated pathways, involved in tumor development and metastasis. Here, we discuss the findings on the mechanisms involved in regulating TRIM25 expression and its functional relevance in breast cancer progression. These studies suggest that TRIM25 may be a biomarker and a therapeutic target for breast cancer.

TRIM25 regulates oxaliplatin resistance in colorectal cancer by promoting EZH2 stability

Resistance to chemotherapy remains the major cause of treatment failure in patients with colorectal cancer (CRC). Here, we identified TRIM25 as an epigenetic regulator of oxaliplatin (OXA) resistance in CRC. The level of TRIM25 in OXA-resistant patients who experienced recurrence during the follow-up period was significantly higher than in those who had no recurrence. Patients with high expression of TRIM25 had a significantly higher recurrence rate and worse disease-free survival than those with low TRIM25 expression. Downregulation of TRIM25 dramatically inhibited, while overexpression of TRIM25 increased, CRC cell survival after OXA treatment. In addition, TRIM25 promoted the stem cell properties of CRC cells both in vitro and in vivo. Importantly, we demonstrated that TRIM25 inhibited the binding of E3 ubiquitin ligase TRAF6 to EZH2, thus stabilizing and upregulating EZH2, and promoting OXA resistance. Our study contributes to a better understanding of OXA resistance and indicates that inhibitors against TRIM25 might be an excellent strategy for CRC management in clinical practice.

The translational values of TRIM family in pan-cancers: From functions and mechanisms to clinics

Cancer is the second leading cause of human death across the world. Tripartite motif (TRIM) family, with E3 ubiquitin ligase activities in majority of its members, is reported to be involved in multiple cellular processes and signaling pathways. TRIM proteins have critical effects in the regulation of biological behaviors of cancer cells. Here, we discussed the current understanding of the molecular mechanism of TRIM proteins regulation of cancer cells. We also comprehensively reviewed published studies on TRIM family members as oncogenes or tumor suppressors in the oncogenesis, development, and progression of a variety of types of human cancers. Finally, we highlighted that certain TRIM family members are potential molecular biomarkers for cancer diagnosis and prognosis, and potential therapeutic targets.

LncRNA XIST upregulates TRIM25 via negatively regulating miR-192 in hepatitis B virus-related hepatocellular carcinoma

BACKGROUND

Long non-coding RNA (lncRNA) XIST has been implicated in the progression of a variety of tumor diseases. The purpose of this study was to explore the molecular role of lncRNA XIST in human hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC).

METHODS

The expression levels of lncRNA XIST, miR-192 and TRIM25 in HBV-related HCC tissues and HepG2.2.15 cells were detected by qRT-PCR. Biological information and luciferin gene reporter assay were performed to detect the interaction among lncRNA XIST, miR-192 and TRIM25. CCk-8 assay, wound healing assay and colony formation assay were conducted to detect the proliferation and migration ability of HepG2.2.15 cells.

RESULTS

qRT-PCR results showed that the expression levels of lncRNA XIST were remarkably increased in HBV-related HCC tissues and HepG2.2.15 cells. In addition, miR-192 was a direct target gene of lncRNA XIST, and the expression of miR-192 and lncRNA XIST were negatively correlated. Moreover, overexpression of miR-192 observably inhibited the proliferation and migration of HCC cells, while overexpression of lncRNA XIST showed an opposite effect. Furthermore, TRIM25 was a direct target of miR-192, and lncRNA XIST could up-regulate the expression of TRIM25 by targeting miR-192.

CONCLUSION

LncRNA XIST could up-regulate the expression of TRIM25 by targeting and binding to miR-192, thus accelerating the occurrence and development of HCC.

E3 Ubiquitin Ligase in Anticancer Drugdsla Resistance: Recent Advances and Future Potential

Drug therapy is the primary treatment for patients with advanced cancer. The use of anticancer drugs will inevitably lead to drug resistance, which manifests as tumor recurrence. Overcoming chemoresistance may enable cancer patients to have better therapeutic effects. However, the mechanisms underlying drug resistance are poorly understood. E3 ubiquitin ligases (E3s) are a large class of proteins, and there are over 800 putative functional E3s. E3s play a crucial role in substrate recognition and catalyze the final step of ubiquitin transfer to specific substrate proteins. The diversity of the set of substrates contributes to the diverse functions of E3s, indicating that E3s could be desirable drug targets. The E3s MDM2, FBWX7, and SKP2 have been well studied and have shown a relationship with drug resistance. Strategies targeting E3s to combat drug resistance include interfering with their activators, degrading the E3s themselves and influencing the interaction between E3s and their substrates. Research on E3s has led to the discovery of possible therapeutic methods to overcome the challenging clinical situation imposed by drug resistance. In this article, we summarize the role of E3s in cancer drug resistance from the perspective of drug class.

TRIM Proteins in Colorectal Cancer: TRIM8 as a Promising Therapeutic Target in Chemo Resistance

Colorectal cancer (CRC) represents one of the most widespread forms of cancer in the population and, as all malignant tumors, often develops resistance to chemotherapies with consequent tumor growth and spreading leading to the patient’s premature death. For this reason, a great challenge is to identify new therapeutic targets, able to restore the drugs sensitivity of cancer cells. In this review, we discuss the role of TRIpartite Motifs (TRIM) proteins in cancers and in CRC chemoresistance, focusing on the tumor-suppressor role of TRIM8 protein in the reactivation of the CRC cells sensitivity to drugs currently used in the clinical practice. Since the restoration of TRIM8 protein levels in CRC cells recovers chemotherapy response, it may represent a new promising therapeutic target in the treatment of CRC.

Regulation of p53 by E3s

More than 40 years of research on p53 have given us tremendous knowledge about this protein. Today we know that p53 plays a role in different biological processes such as proliferation, invasion, pluripotency, metabolism, cell cycle control, ROS (reactive oxygen species) production, apoptosis, inflammation and autophagy. In the nucleus, p53 functions as a bona-fide transcription factor which activates and represses transcription of a number of target genes. In the cytoplasm, p53 can interact with proteins of the apoptotic machinery and by this also induces cell death. Despite being so important for the fate of the cell, expression levels of p53 are kept low in unstressed cells and the protein is largely inactive. The reason for the low expression level is that p53 is efficiently degraded by the ubiquitin-proteasome system and the vast inactivity of the tumor suppressor protein under normal growth conditions is due to the absence of activating and the presence of inactivating posttranslational modifications. E3s are important enzymes for these processes as they decorate p53 with ubiquitin and small ubiquitin-like proteins and by this control p53 degradation, stability and its subcellular localization. In this review, we provide an overview about E3s that target p53 and discuss the connection between p53, E3s and tumorigenesis.

TRIM25 contributes to the malignancy of acute myeloid leukemia and is negatively regulated by microRNA-137

Background

Acute myeloid leukemia (AML) is a ubiquitous malignancy that occurs in the hematological system. Tripartite motif-containing 25 (TRIM25) has been found to be involved in various carcinomas comprising AML. However, the function and underlying causative role of TRIM25 in AML are still obscure.

Methods and materials

Quantitative real-time polymerase chain reaction (qPCR) was used for assaying TRIM25 and miR-137 expression in AML samples and cells. CCK-8 assay, Calcein-acetoxymethylester/propidium iodide staining, and Transwell assay were adopted to assay cell proliferation, invasion, and migration. Dual-luciferase reporter experiment was used for analyzing the interaction of TRIM25 with miR-137. Western blot was used for assaying protein expression levels.

Results

This study confirmed that TRIM25 expression was upregulated in AML samples and cell lines, whereas miR-137 expression was downregulated. Overexpression of TRIM25 significantly contributed to AML cell’s proliferation, invasion, and migration, whereas knockdown exerted the opposite effect. In addition, TRIM25 was a downstream target of miR-137 in AML cells and negatively modulated by miR-137.

Conclusion

TRIM25 was targeted and regulated by miR-137, exerted a carcinogenic function in AML, and could be used as a latent biomarker and a treatment target for AML.

TRIM proteins in lung cancer: Mechanisms, biomarkers and therapeutic targets

The tripartite motif (TRIM) family is defined by the presence of a Really Interesting New Gene (RING) domain, one or two B-box motifs and a coiled-coil region. TRIM proteins play key roles in many biological processes, including innate immunity, tumorigenesis, cell differentiation and ontogenetic development. Alterations in TRIM gene and protein levels frequently emerge in a wide range of tumors and affect tumor progression. As canonical E3 ubiquitin ligases, TRIM proteins participate in ubiquitin-dependent proteolysis of prominent components of the p53, NF-κB and PI3K/AKT signaling pathways. The occurrence of ubiquitylation events induced by TRIM proteins sustains internal balance between tumor suppressive and tumor promoting genes. In this review, we summarized the diverse mechanism of TRIM proteins responsible for the most common malignancy, lung cancer. Furthermore, we also discussed recent progress in both the diagnosis and therapeutics of tumors contributed by TRIM proteins.

TRIM25 promotes Capicua degradation independently of ERK in the absence of ATXN1L

Background

Aberrations in Capicua (CIC) have recently been implicated as a negative prognostic factor in a multitude of cancer types through the derepression of targets downstream of the mitogen-activated protein kinase (MAPK) signaling cascade, such as oncogenic E26 transformation-specific (ETS) transcription factors. The Ataxin-family protein ATXN1L has previously been reported to interact with CIC in both developmental and disease contexts to facilitate the repression of CIC target genes and promote the post-translational stability of CIC. However, little is known about the mechanisms at the base of ATXN1L-mediated CIC post-translational stability.

Results

Functional in vitro studies utilizing ATXN1L^KO human cell lines revealed that loss of ATXN1L leads to the accumulation of polyubiquitinated CIC protein, promoting its degradation through the proteasome. Although transcriptomic signatures of ATXN1L^KO cell lines indicated upregulation of the mitogen-activated protein kinase pathway, ERK activity was found to contribute to CIC function but not stability. Degradation of CIC protein following loss of ATXN1L was instead observed to be mediated by the E3 ubiquitin ligase TRIM25 which was further validated using glioma-derived cell lines and the TCGA breast carcinoma and liver hepatocellular carcinoma cohorts.

Conclusions

The post-translational regulation of CIC through ATXN1L and TRIM25 independent of ERK activity suggests that the regulation of CIC stability and function is more intricate than previously appreciated and involves several independent pathways. As CIC status has become a prognostic factor in several cancer types, further knowledge into the mechanisms which govern CIC stability and function may prove useful for future therapeutic approaches.

OTUD5 cooperates with TRIM25 in transcriptional regulation and tumor progression via deubiquitination activity

Oncogenic processes exert their greatest effect by targeting regulators of cell proliferation. Studying the mechanism underlying growth augmentation is expected to improve clinical therapies. The ovarian tumor (OTU) subfamily deubiquitinases have been implicated in the regulation of critical cell-signaling cascades, but most OTUs functions remain to be investigated. Through an unbiased RNAi screen, knockdown of OTUD5 is shown to significantly accelerate cell growth. Further investigation reveals that OTUD5 depletion leads to the enhanced transcriptional activity of TRIM25 and the inhibited expression of PML by altering the ubiquitination level of TRIM25. Importantly, OTUD5 knockdown accelerates tumor growth in a nude mouse model. OTUD5 expression is markedly downregulated in tumor tissues. The reduced OTUD5 level is associated with an aggressive phenotype and a poor clinical outcome for cancers patients. Our findings reveal a mechanism whereby OTUD5 regulates gene transcription and suppresses tumorigenesis by deubiquitinating TRIM25, providing a potential target for oncotherapy.

Emerging RNA-binding roles in the TRIM family of ubiquitin ligases

TRIM proteins constitute a large, diverse and ancient protein family which play a key role in processes including cellular differentiation, autophagy, apoptosis, DNA repair, and tumour suppression. Mostly known and studied through the lens of their ubiquitination activity as E3 ligases, it has recently emerged that many of these proteins are involved in direct RNA binding through their NHL or PRY/SPRY domains. We summarise the current knowledge concerning the mechanism of RNA binding by TRIM proteins and its biological role. We discuss how RNA-binding relates to their previously described functions such as E3 ubiquitin ligase activity, and we will consider the potential role of enrichment in membrane-less organelles.

TRIM25 and its emerging RNA-binding roles in antiviral defense

The innate immune system is the body's first line of defense against viruses, with pattern recognition receptors (PRRs) recognizing molecules unique to viruses and triggering the expression of interferons and other anti-viral cytokines, leading to the formation of an anti-viral state. The tripartite motif containing 25 (TRIM25) is an E3 ubiquitin ligase thought to be a key component in the activation of signaling by the PRR retinoic acid-inducible gene I protein (RIG-I). TRIM25 has recently been identified as an RNA-binding protein, raising the question of whether its RNA-binding activity is important for its role in innate immunity. Here, we review TRIM25's mechanisms and pathways in noninfected and infected cells. We also introduce models that explain how TRIM25 binding to RNA could modulate its functions and play part in the antiviral response. These findings have opened new lines of investigations into functional and molecular roles of TRIM25 and other E3 ubiquitin ligases in cell biology and control of pathogenic infections. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition.

Identification of TRIM25 as a Negative Regulator of Caspase-2 Expression Reveals a Novel Target for Sensitizing Colon Carcinoma Cells to Intrinsic Apoptosis

Colorectal cancer (CRC) is one of the most common cancers that is characterized by a high mortality due to the strong metastatic potential of the primary tumor and the high rate of therapy resistance. Hereby, evasion of apoptosis is the primary underlying cause of reduced sensitivity of tumor cells to chemo- and radiotherapy. Using RNA affinity chromatography, we identified the tripartite motif-containing protein 25 (TRIM25) as a bona fide caspase-2 mRNA-binding protein in colon carcinoma cells. Loss-of-function and gain-of-function approaches revealed that TRIM25 attenuates the protein levels of caspase-2 without significantly affecting caspase-2 mRNA levels. In addition, experiments with cycloheximide revealed that TRIM25 does not affect the protein stability of caspase-2. Furthermore, silencing of TRIM25 induced a significant redistribution of caspase-2 transcripts from RNP particles to translational active polysomes, indicating that TRIM25 negatively interferes with caspase-2 translation. Functionally, the elevation in caspase-2 upon TRIM25 depletion significantly increased the sensitivity of colorectal cells to drug-induced intrinsic apoptosis as implicated by increased caspase-3 cleavage and cytochrome c release. Importantly, the apoptosis-sensitizing effects by transient TRIM25 knockdown were rescued by concomitant silencing of caspase-2, demonstrating a critical role of caspase-2. Inhibition of caspase-2 by TRIM25 implies a survival mechanism that critically contributes to chemotherapeutic drug resistance in CRC.

The deubiquitylase OTUD3 stabilizes GRP78 and promotes lung tumorigenesis

The deubiquitylase OTUD3 plays a suppressive role in breast tumorigenesis through stabilizing PTEN protein, but its role in lung cancer remains unclear. Here, we demonstrate that in vivo deletion of OTUD3 indeed promotes breast cancer development in mice, but by contrast, it slows down Kras^G12D-driven lung adenocarcinoma (ADC) initiation and progression and markedly increases survival in mice. Moreover, OTUD3 is highly expressed in human lung cancer tissues and its higher expression correlates with poorer survival of patients. Further mechanistic studies reveal that OTUD3 interacts with, deubiquitylates and stabilizes the glucose-regulated protein GRP78. Knockdown of OTUD3 results in a decrease in the level of GRP78 protein, suppression of cell growth and migration, and tumorigenesis in lung cancer. Collectively, our results reveal a previously unappreciated pro-oncogenic role of OTUD3 in lung cancer and indicate that deubiquitylases could elicit tumor-suppressing or tumor-promoting activities in a cell- and tissue-dependent context.

The deubiquitylase OTUD3 can function as a tumour-suppressor by stabilizing PTEN. Here, the authors show that OTUD3 also has an oncogenic role in lung cancer by stabilizing the glucose-regulated protein GRP78.

The MAP3K13-TRIM25-FBXW7α axis affects c-Myc protein stability and tumor development

c-Myc (Myc) is a master transcription factor that is often deregulated and highly expressed by at least 50% of cancers. In many cases, Myc protein levels correlate with resistance to therapy and poor prognosis. However, effective direct inhibition of Myc by pharmacologic approaches has remained unachievable. Here, we identify MAP3K13 as a positive regulator of Myc to promote tumor development. Our findings show that MAP3K13 upregulation is predictive of poor outcomes in patients with hepatocellular carcinoma (HCC). Mechanistically, MAP3K13 phosphorylates the E3 ubiquitin ligase TRIM25 at Ser₁₂ to decrease its polyubiquitination and proteasomal degradation. This newly stabilized TRIM25 then directly ubiquitinates Lys₄₁₂ of FBXW7α, a core subunit of the SKP1-Cullin-F-box (SCF) ubiquitin ligase complex involved in Myc ubiquitination, thereby stabilizing Myc. Together, these results reveal a novel regulatory pathway that supervises Myc protein stability via the MAP3K13-TRIM25-FBXW7α signaling axis. In addition, they provide a potential therapeutic target in Myc over-expressing human cancers.

Altered expression of microRNA-365 is related to the occurrence and development of non-small-cell lung cancer by inhibiting TRIM25 expression

The purpose of this current study is to elucidate whether altered microRNA-365 (miR-365) has an association with the initiation and development of non-small-cell lung cancer (NSCLC) by targeting TRIM25 expression. The expression of miR-365 and TRIM25 in NSCLC tissues, adjacent normal tissues, and NSCLC cell lines were detected. The relationship between miR-365 expression and TRIM25 with the clinicopathological characteristics of NSCLC was analyzed. The putative binding site between miR-365 and TRIM25 was determined by luciferase activity assay. miR-365 inhibitors and miR-365 mimics were transfected to human NSCLC A549 cells, and the cell viability was detected by cell counting kit-8 assay; flow cytometry was carried out to determine cell cycle and apoptosis rate. Poorly expressed miR-365 and overexpressed TRIM25 was found in NSCLC tissues. TRIM25 was determined as a target gene of miR-365. The miR-365 and TRIM25 expression were related to the clinicopathological features of NSCLC, such as pathological classification, differentiation degree, TNM stage as well as lymph node metastasis. miR-365 suppressed the expression of TRIM25 and elevated the expression of the proapoptotic protein in NSCLC cells. Our study demonstrates that altered expression of miR-365 has a close association with the occurrence and development of NSCLC by inhibiting TRIM25 expression.

Blockade of miR-3614 maturation by IGF2BP3 increases TRIM25 expression and promotes breast cancer cell proliferation

BACKGROUND

The cross-talk between RNA binding proteins (RBPs) and microRNAs (miRNAs) in the regulation of gene expression is a complex process. Here, we describe a new mode of regulation of TRIM25 expression mediated by an antagonistic interplay between IGF2BP3 and miR-3614-3p.

METHODS

The expression level of TRIM25, IGF2BP3, pri-miR-3614 and miR-3614-3p in breast cancer (BC) tissues, non-tumor tissues and BC cell lines were detected by qRT-PCR, Western blot and Immunohistochemistry (IHC). Binding of miR-3614-3p and IGF2BP3 to TRIM25 RNA was verified using luciferase activation assays, RNA immunoprecipitation (RIP) and biotin pull-down assays. In vitro and in vivo loss- and gain-of-function studies were performed to reveal the effects and related mechanism of IGF2BP3-miR-3614-3p-TRIM25 axis in in breast cancer cells proliferation.

FINDINGS

We found that an intragenic miRNA-3614-3p inhibits the expression of its host gene TRIM25 by binding to its 3'- untranslated region (UTR). Interestingly, IGF2BP3 can competitively occupy this binding site and inhibit miRNA-3614 maturation, thereby protecting TRIM25 mRNA from miR-3614-mediated degradation. The overexpression of miR-3614-3p dramatically inhibited breast cancer cell growth through the downregulation of TRIM25. Furthermore, the silencing of IGF2BP3 reduced TRIM25 expression, suppressed cell proliferation, and exhibited a synergistic effect with miR-3614-3p overexpression.

INTERPRETATION

Collectively, these results demonstrate that control of TRIM25 RNA by an interplay between IGF2BP3 and miR-3614-3p represents a mechanism for breast cancer cell proliferation. FUND: The scientific research and sharing platform construction project of Shaanxi Province, Opening Project of Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, China Postdoctoral Science Foundation and The National Natural Science Foundation of China.

Efp promotes in vitro and in vivo growth of endometrial cancer cells along with the activation of nuclear factor-κB signaling

Endometrial cancer is common among postmenopausal women and its incidence is increasing in developed countries. Considering that >80% of endometrial cancers are assumed to be estrogen-related, higher estrogen exposure will be relevant to tumorigenesis. Therefore, the roles of estrogen target genes will be important to understand the pathophysiological mechanisms. We previously revealed that estrogen-responsive RING finger protein Efp contributes to breast cancer progression through the protein degradation of cell cycle checkpoint 14-3-3σ. We and others also proposed that Efp has tumor-promoting activities in estrogen receptor (ER)-negative cancer cells. In addition, Efp plays a role in type I interferon production by activating antiviral signaling, which provokes nuclear factor-κB (NF-κB) signaling. In the present study, we investigate whether Efp plays a critical role in endometrial cancer biology. We show that siRNA-mediated Efp knockdown represses the proliferation and migration of endometrial cancer ER-positive Ishikawa and ER-negative HEC-1A cells. Efp knockdown increases 14-3-3σ protein levels and decreases the rates proliferative stage cells. Efp siRNA significantly inhibits the in vivo tumor growth of endometrial cancer cells in both subcutaneous and orthotopic xenograft models. Intriguingly, Efp knockdown represses NF-κB-dependent transactivation and transcription of target genes, such as IL6ST and IL18, in endometrial cancer cells. Overall, Efp would exert a tumor-promoting role through modulating NF-κB pathway and 14-3-3σ protein degradation in endometrial cancer regardless of its estrogen receptor status. Our results indicate that Efp could be a potential diagnostic and therapeutic target for endometrial cancer.

Mechanism of TRIM25 mediated ubiquitination of metastasis associated protein (MTA) 1 in normal liver cells

Ninety percent of all cancer related deaths happen due to metastatic progression. One important protein facilitating metastatic progression in hepatocellular carcinoma (HCC) is the metastasis associated 1 protein (MTA-1). We have earlier shown that in the context of HCC and normal liver cell lines, HuH6 and THLE-2, respectively. MTA-1 protein is actively stabilized in HCC cell lines and actively degraded in normal liver cells. We had also shown that TRIM25 is the E3 ligase that interacts with and degrades MTA-1 protein in normal liver cells. However, the exact mechanism by which TRIM25 degrades MTA-1 protein has still not been elucidated. In the study, we used both in situ prediction algorithms and mass spectrometry based post-translational modification analysis to map the lysine residues in MTA-1 that are polyubiquitinated. Whereas UbPred algorithm revealed a combination of medium and low confidence sites, it revealed only one high confidence lysine (K98) residue. The hCKSAAP_UbSite algorithm also predicted K98 site. Mass spectrometry analysis also showed that K98 has ubiquitin modification. Immunofluorescence analysis showed that in normal liver cell line, THLE-2, which has high expression of TRIM25, ectopically expressed FLAG-tagged wild-type MTA-1 was actively degraded, but the K98R mutant MTA-1 was not. In vitro ubiquitination assay using recombinant wild-type and K98R mutant MTA-1 confirmed that MTA-1 is poly-ubiquitinated at K98 residue by TRIM25. The K98R mutant had a longer half-life than wild-type MTA-1 protein in an in vitro protein stability assay. We establish that TRIM25 ubiquitinates MTA-1 at lysine 98 and degrades it normal liver cells.

Knockdown of TRIM66 inhibits malignant behavior and epithelial-mesenchymal transition in non-small cell lung cancer

OBJECTIVE

The tripartite motif 66(TRIM66) is an important member of the TRIM protein superfamily, which can participate in the expression of multiple proteins, and is closely associated with the behaviors of non-small cell lung cancer (NSCLC). In this study, we aimed to explore the effect of TRIM66 in this process in vitro using NSCLC cell lines, and the role of TRIM66 in regulating epithelial-mesenchymal transition(EMT) in NSCLC.

METHODS

Western blotting was used to detect the TRIM66 protein expression levels in NSCLC cell lines and normal lung epithelial cells BEAS-2B. We silenced its expression in A549 cells by transient siRNA transfection to ascertain the function of TRIM66 in NSCLC cells. Western blotting was used to detect the expression of EMT-related proteins.

RESULTS

TRIM66 protein content was highest in NSCLC cell line A549, compared with BEAS-2B, it showed that the TRIM66-siRNA group lung cancer cell proliferation was significantly reduced after knockdown of TRIM66, and knockdown of TRIM66 also suppressed invasion, migration and clonogenic ability of A549 cells. Finally, we found that siRNA-mediated TRIM66 silencing suppressed EMT by downregulating expression of N-cadherin and vimentin and upregulating that of E-cadherin in NSCLC cells, which could effectively reduce the invasive, migratory, and proliferative capacities of lung cancer cells.

CONCLUSION

Silence TRIM66 expression suppressed NSCLC cell proliferation, invasion, and migration. The siRNA-mediated TRIM66 silencing could block the occurrence of EMT. TRIM66 could be a promising novel target for future NSCLC treatments.

DeSUMOylation switches Kaiso from activator to repressor upon hyperosmotic stress

Kaiso is a member of the BTB/POZ zinc finger family, which is involved in cancer progression, cell cycle control, apoptosis, and WNT signaling. Depending on promoter context, it may function as either a transcriptional repressor or activator. Previous studies found that Kaiso might be SUMOylated due to heat shock, but the biological significance of Kaiso SUMOylation is unclear. Here, we find that K42 is the only amino acid within Kaiso that is modified with SUMO. Kaiso is monoSUMOylated at lysine 42 in cell lines of kidney origin under normal physiological conditions. SUMOylated Kaiso can activate transcription from exogenous methylated promoters, wherein the deSUMOylated form of the protein kept the ability to be a repressor. Rapid Kaiso deSUMOylation occurs in response to hyperosmotic stress and is reversible upon return to an isotonic environment. DeSUMOylation occurs within minutes in HEK293 cells treated with 100 mM NaCl and relaxes in 3 h even in a salt-containing medium. Genomic editing of Kaiso by conversion of K42 into R42 (K42R) in HEK293 cells that resulted in fully deSUMOylated endogenous protein led to misregulation of genes associated with ion transport, blood pressure, and the immune response. TRIM25 was significantly repressed in two K42R HEK293 clones. By a series of rescue experiments with K42R and KO HEK293 cells, we show that TRIM25 is a direct transcriptional target for Kaiso. In the absence of Kaiso, the level of TRIM25 is insensitive to hyperosmotic stress. Extending our observations to animal models, we show that in response to a high salt diet, Kaiso knockout mice are characterized by significantly higher blood pressure increases when compared to wild-type animals. Thus, we propose a novel biological role for Kaiso in the regulation of homeostasis.

TRIM56 Suppresses Multiple Myeloma Progression by Activating TLR3/TRIF Signaling

PURPOSE

Tripartite-motif-containing protein 56 (TRIM56) has been found to exhibit a broad antiviral activity, depending upon E3 ligase activity. Here, we attempted to evaluate the function of TRIM56 in multiple myeloma (MM) and its underlying molecular basis.

MATERIALS AND METHODS

TRIM56 expression at the mRNA and protein level was measured by qRT PCR and western blot analysis. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and flow cytometry analysis was performed to investigate the effect of TRIM56 on MM cell proliferation and apoptosis. The concentrations of interferon (IFN)-β, interleukin (IL)-6, and tumor necrosis factor-α in MM cell culture supernatants were detected with respective commercial ELISA kits. Western blot was employed to determine the effect of TRIM56 on toll-like receptor 3 (TLR3)/toll-IL-1 receptor (TIR) domain-containing adaptor inducing IFN-β (TRIF) signaling pathway.

RESULTS

TRIM56 expression was prominently decreased in MM cells. Poly (dA:dT)-induced TRIM56 overexpression in U266 cells suppressed proliferation, induced apoptosis, and enhanced inflammatory cytokine production, while TRIM56 knockdown improved growth, diminished apoptosis, and inhibited inflammatory cytokine secretion in RPMI8226 cells. Moreover, TRIM56 knockdown blocked TLR3 signaling pathway. Furthermore, poly (I:C), a TLR3 agonist, markedly abolished TRIM56 depletion-induced increase of proliferation, decrease of apoptosis, and reduction of inflammatory factor in MM cells.

CONCLUSION

TRIM56 may act as a tumor suppressor in MM through activation of TLR3/TRIF signaling pathway, contributing to a better understanding of the molecular mechanism of TRIM56 involvement in MM pathogenesis and providing a promising therapy strategy for patients with MM.

Nitroxoline shows antimyeloma activity by targeting the TRIM25/p53 axle

The aim of this study was to identify the most potent quinoline-based anti-infectives for the treatment of multiple myeloma (MM) and to understand the molecular mechanisms. A small-scale screen against a panel of marketed quinoline-based drugs was performed in MM cell lines. Cell apoptosis was examined by flow cytometry. Anti-MM activity was also evaluated in nude mice. Western blotting was performed to investigate mechanisms. Nitroxoline (NXQ) was the most effective in suppressing MM cell proliferation. NXQ induced more than 40% MM cell apoptosis within 24 h and potentiated anti-MM activities of current major drugs including doxorubicin and lenalidomide. This finding was shown by activation of caspase-3, a major executive apoptotic enzyme, and by inactivation of PARP, a major enzyme in DNA damage repair. NXQ also suppressed prosurvival proteins Bcl-xL and Mcl-1. Moreover, NXQ suppressed the growth of myeloma xenografts in nude mice models. In the mechanistic study, NXQ was found to downregulate TRIM25, a highly expressed ubiquitin ligase in MM. Notably, NXQ upregulated tumor suppressor p53, but not PTEN. Furthermore, overexpression of TRIM25 decreased p53 protein. This study indicated that the long-term use of anti-infective NXQ has potential for MM treatment by targeting the TRIM25/p53 axle.

The ubiquitin ligase TRIM25 inhibits hepatocellular carcinoma progression by targeting metastasis associated 1 protein

Metastasis associated 1 protein (MTA1) is one of the prime facilitators of metastatic progression in all solid tumors including hepatocellular carcinoma (HCC). However, the underlying regulatory mechanism of MTA1 expression in HCC is not clear. In this study, we evaluated MTA1 transcript and protein expression in HCC and normal hepatic cell lines. The results revealed that MTA1 protein expression had a significantly increase in HCC cell line, HuH6, compared with that in normal hepatic cell line, THLE-2. Determination of protein half-life using cycloheximide (CHX) treatment did not reveal any statistically significant difference in protein turn-over rates between THLE-2 (3.3 ± 0.25 h) and HuH6 (3.6 ± 0.15 h) cell lines. MTA1 protein level was stabilized in THLE-2 cells after treatment with MG-132 to levels similar to those observed in HuH6 cells. Mass spectrometric analysis of FLAG immunoprecipitates of FLAG-MTA1 transfected THLE-2 cells after MG-132 treated revealed candidate ubiquitin ligases that were interacting with MTA1. RNAi-mediated silencing of each prospective ubiquitin ligase in THLE-2 cells indicated that knockdown of TRIM25 resulted in stabilization of MTA1 protein, indicating TRIM25 as a putative E3 ligase for MTA1. Coimmunoprecipitation of FLAG-tagged MTA1, but not IgG, in MG-132 treated and untreated THLE-2 cells cotransfected with either FLAG-MTA1 or Myc-TRIM25 revealed robust polyubiquitinated MTA1, confirming that the TRIM25 is the ubiquitin ligase for MTA1 degradation. Overexpression of TRIM25 in HuH6 and RNAi mediated silencing of TRIM25 in THLE-2 cells inhibited and increased the cell migration and invasion, respectively. Analysis of The Cancer Genome Atlas data for assessment of TRIM25 transcript level and MTA1 protein expression in 25 HCC patients confirmed an inverse correlation between the expression of TRIM25 and MTA1. Cumulatively, our data reveal a novel mechanism of post-translational to regulate MTA1 expression in normal hepatic cells, which is repressed in HCC. © 2017 IUBMB Life, 69(10):795-801, 2017.

TRIM25 in the Regulation of the Antiviral Innate Immunity

TRIM25 is an E3 ubiquitin ligase enzyme that is involved in various cellular processes, including regulation of the innate immune response against viruses. TRIM25-mediated ubiquitination of the cytosolic pattern recognition receptor RIG-I is an essential step for initiation of the intracellular antiviral response and has been thoroughly documented. In recent years, however, additional roles of TRIM25 in early innate immunity are emerging, including negative regulation of RIG-I, activation of the melanoma differentiation-associated protein 5–mitochondrial antiviral signaling protein–TRAF6 antiviral axis and modulation of p53 levels and activity. In addition, the ability of TRIM25 to bind RNA may uncover new mechanisms by which this molecule regulates intracellular signaling and/or RNA virus replication.

TRIM25 is associated with cisplatin resistance in non-small-cell lung carcinoma A549 cell line via downregulation of 14-3-3σ

Lung cancer, in particular, non-small cell lung cancer (NSCLC), is the leading cause of cancer-related mortality. Cis-Diamminedichloroplatinum (cisplatin, CDDP) as first-line chemotherapy for NSCLC, but resistance occurs frequently. We previously reported that Tripartite motif protein 25 (TRIM25) was highly expressed in cisplatin-resistant human lung adenocarcinoma A549 cells (A549/CDDP) in comparison with its parental A549 cells. Herein, we take a further step to demonstrate the association of TRIM25 and cisplatin resistance and also the underlying mechanisms. Knockdown of TRIM25 by RNA interference in A549/CDDP cells decreased half maximal inhibitory concentration (IC₅₀) values and promoted apoptosis in response to cisplatin, whereas overexpression of TRIM25 had opposite effects. More importantly, we found that concomitant knockdown of 14-3-3σ and TRIM25 absolutely reversed the decreased MDM2, increased p53, increased cleaved-Capsese3 and decreased IC₅₀ value induced by knockdown of TRIM25 individually, suggesting that TRIM25 mediated cisplatin resistance primarily through downregulation of 14-3-3σ. Our results indicate that TRIM25 is associated with cisplatin resistance and 14-3-3σ-MDM2-p53 signaling pathway is involved in this process, suggesting targeting TRIM25 may be a potential strategy for the reversal of cisplatin resistance.

Tripartite motif containing 25 promotes proliferation and invasion of colorectal cancer cells through TGF-β signaling

Tripartite motif containing 25 (TRIM25) is a member of TRIM proteins and functions as an E3 (ubiquitin ligase). It has been found to act as an oncogene in gastric cancer cells and is abnormally expressed in cancers in female reproductive system. Here, we investigated the function of TRIM25 in colorectal cancer. TRIM25 was found to be significantly up-regulated in colorectal cancer tissues and cancer cell lines through real-time PCR assay. Colorectal cancer cells (CRCs) overexpressing TRIM25 exhibited a two-fold higher proliferation and migration rate compared with their parental lines in vitro Moreover, TRIM25 also promoted tumor progression in vivo Further study indicated that TRIM25 worked through positively regulating transforming growth factor β (TGF-β) signaling pathway to regulate the proliferation and invasion of CRCs. In summary, our results indicate that TRIM25 also acts as an oncogene in colorectal cancer and it functions through TGF-β signaling pathway. Thus, TRIM25 represents potential targets for the treatment of colorectal cancer.

TRIM11 overexpression promotes proliferation, migration and invasion of lung cancer cells

BACKGROUND

Tripartite Motif Containing 11 (TRIM11), a member of TRIM proteins, is overexpressed in high-grade gliomas and plays an oncogenic function in glioma biology. However, little is known about the role of TRIM11 in lung cancer.

METHODS

We analyzed TRIM11 mRNA expression in lung cancer tissues and adjacent non-neoplastic tissues by real-time PCR. We then explored the function of TRIM11 in lung cancer cells by small interfering RNA-mediated downregulation of this protein followed by analyses of cell proliferation, migration and invasion.

RESULTS

TRIM11 was highly expressed in lung cancer tissues and lung cancer cell lines. The higher expression of TRIM11 was correlated with the poorer prognosis of patients. Suppressing of TRIM11 expression in lung cancer cells with higher expression of TRIM11 (A549 and NCI-H446 cells) significantly reduced cell growth, motility and invasiveness. We further demonstrated that knockdown of TRIM11 affected the expression of cell proliferation-related proteins (Cyclin D1 and PCNA), and epithelial-mesenchymal transformation-related proteins (VEGF, MMP-2, MMP-9, Twist1, Snail and E-cadherin). The activity of ERK and PI3K/AKT was also suppressed in TRIM11 knocked down cells. Further experiments in lung cells with lower expression of TRIM11 (NCI-H460 and NCI-H1975 cells) with AKT inhibitor suggested that TRIM11 may promote cell motility and invasiveness through AKT pathway.

CONCLUSIONS

Our results indicate that TRIM11 acts as an oncogene in lung cancer through promoting cell growth, migration and invasion. Our findings may have important implication for the detection and treatment of lung cancer.

A novel TRIM family member, Trim69, regulates zebrafish development through p53-mediated apoptosis

Trim69 contains the hallmark domains of a tripartite motif (TRIM) protein, including a Ring-finger domain, B-box domain, and coiled-coil domain. Trim69 is structurally and evolutionarily conserved in zebrafish, mouse, rat, human, and chimpanzee. The role of this protein is unclear, however, so we investigated its function in zebrafish development. Trim69 is extensively expressed in zebrafish adults and developing embryos-particularly in the testis, brain, ovary, and heart-and its expression decreases in a time- and stage-dependent manner. Loss of trim69 in zebrafish induces apoptosis and activates apoptosis-related processes; indeed, the tp53 pathway was up-regulated in response to the knockdown. Expression of human trim69 rescued the apoptotic phenotype, while overexpression of trim69 does not increase cellular apoptosis. Taken together, our results suggest that trim69 participates in tp53-mediated apoptosis during zebrafish development. Mol. Reprod. Dev. 83: 442-454, 2016. © 2016 Wiley Periodicals, Inc.

TRIMming p53's anticancer activity

Several TRIM proteins control abundance and activity of p53. Along this route, TRIM proteins have a serious impact on carcinogenesis and prognosis for cancer patients. In the past years, a significant increase has been made in our understanding of how the TRIM protein family controls p53 activity.

TRIM25 blockade by RNA interference inhibited migration and invasion of gastric cancer cells through TGF-β signaling

Tripartite Motif Containing 25 (TRIM25), a member of TRIM proteins, has been found abnormally expressed in cancers of female reproductive system. Here, TRIM25 was conspicuously expressed in human gastric cancer (GC) tissues in which its higher expression generally correlated with the poor prognosis of patients. Small interfering RNA (siRNA)-mediated knockdown of TRIM25 expression in MGC-803 and AGS cells had no effects on cell proliferation, whereas reduced cell migration and invasion. Gene set enrichment analysis on The Cancer Genome Atlas stomach adenocarcinoma (STAD) dataset revealed that several signaling pathways, including the migration, E-cadherin and transforming growth factor-β (TGF-β) pathways, were enriched in TRIM25 higher expression patients. Moreover, ectopic expression of TRIM25 in a GC cell line with lower expression of TRIM25 significantly promoted the migration and invasion. Further experiments with TGF-β inhibitor suggested that TRIM25 may exert its function through TGF-β pathway. In summary, our results indicate that TRIM25 acts as an oncogene in GC and thus presents a novel target for the detection and treatment of GC.