The TRIM-FLMN protein TRIM45 directly interacts with RACK1 and negatively regulates PKC-mediated signaling pathway

Identification and characterization of chicken TRIM45 and its role as a negative regulator of ALV-J replication in vitro

Avian leukosis virus subgroup J (ALV-J) is an alpharetrovirus that infects chickens, causing immunosuppression and a decrease in production performance, leading to substantial economic losses in the poultry industry. ALV-J is also well-known for its oncogenic properties, inducing tumours such as myelomas and haemangiomas in infected chickens. TRIM45 has been identified as a potential tumour suppressor; however, the relationship between TRIM45 expression and ALV-J infection remains to be elucidated. This study aimed to dissect the molecular characteristics of the chicken TRIM45 gene and its modulation during ALV-J infection, as well as its influence on viral replication. We found that the chicken TRIM45 RING domain is significantly different from that of humans and other mammals. TRIM45 is expressed in all chicken tissues, with the highest levels in the heart. Subcellular localization studies indicated a cytoplasmic distribution of TRIM45, forming aggregates within cells. Our findings demonstrate that ALV-J infection significantly upregulates TRIM45 expression in DF-1 cells. To assess the functional role of TRIM45 in ALV-J replication, we employed both gene silencing and overexpression strategies. Strikingly, the overexpression of TRIM45, including a mutant lacking the RING domain, was found to markedly suppress ALV-J replication. In contrast, TRIM45 knockdown via siRNA resulted in an enhanced viral replication, highlighting the importance of TRIM45 limiting ALV-J replication. Mechanistically, overexpression of TRIM45 induces apoptosis in infected cells, independent of its RING domain function. In conclusion, our study demonstrates that chicken TRIM45 acts as a negative regulator of ALV-J replication in vitro by promoting apoptosis in infected cells.RESEARCH HIGHLIGHTSChicken TRIM45 RING domain and protein localization significantly differ from humans.TRIM45 negatively regulates ALV-J replication in vitro.TRIM45 inhibits ALV-J replication by inducing apoptosis in infected cells.

Tripartite motif family - its role in tumor progression and therapy resistance: a review

PURPOSE OF REVIEW

In this review, we summarized published articles on the role of tripartite motif (TRIM) family members in the initiation and development of human malignancies.

RECENT FINDINGS

The ubiquitin-proteasome system (UP-S) plays a critical role in cellular activities, and UP-S dysregulation contributes to tumorigenesis. One of the key regulators of the UP-S is the tripartite motif TRIM protein family, most of which are active E3 ubiquitin ligases. TRIM proteins are critical for the biological functions of cancer cells, including migration, invasion, metastasis, and therapy resistance. Therefore, it is important to understand how TRIM proteins function at the molecular level in cancer cells.

SUMMARY

We provide a comprehensive and up-to-date overview about the role TRIMs play in cancer progression and therapy resistance. We propose TRIM family members as potential new markers and targets to overcome therapy failure.

RACK1 Promotes Meningioma Progression by Activation of NF-κB Pathway via Preventing CSNK2B from Ubiquitination Degradation

Higher-grade meningiomas (WHO grade II and III) are characterized by aggressive invasiveness and high postoperative recurrence rates. The prognosis remains inadequate even with adjuvant radiotherapy and currently there is no definitive pharmacological treatment strategy and target for malignant meningiomas. This study aims to unveil the mechanisms driving the malignant progression of meningiomas and to identify potential inhibitory targets, with significant clinical implications. Implementing techniques such as protein immunoprecipitation, mass spectrometry, RNA interference, and transcriptome sequencing, we investigated the malignancy mechanisms in meningioma cell lines IOMM-LEE and CH157-MN. Additionally, in vivo experiments were carried out on nude mice. We discovered a positive correlation between meningioma malignancy and the levels of the receptor for activated C kinase 1 (RACK1), which interacts with CSNK2B, the β subunit of casein kinase 2 (CK2), inhibiting its ubiquitination and subsequent degradation. This inhibition allows CK2 to activate the NF-κb pathway, which increases the transcription of CDK4 and cyclin D3, resulting in the transition of the cell cycle into the G2/M phase. The RACK1 inhibitor, harringtonolide (HA), significantly suppressed the malignant tendencies of meningioma cells. Our study suggests that RACK1 may play a role in the malignant progression of meningiomas, and therefore, targeting RACK1 could emerge as an effective strategy for reducing the malignancy of these tumors.

RACK1 facilitates breast cancer progression by competitively inhibiting the binding of β-catenin to PSMD2 and enhancing the stability of β-catenin

The receptor for activated C kinase 1 (RACK1) is a key scaffolding protein with multifunctional and multifaceted properties. By mediating protein-protein interactions, RACK1 integrates multiple intracellular signals involved in the regulation of various physiological and pathological processes. Dysregulation of RACK1 has been implicated in the initiation and progression of many tumors. However, the exact function of RACK1 in cancer cellular processes, especially in proliferation, remains controversial. Here, we show that RACK1 is required for breast cancer cell proliferation in vitro and tumor growth in vivo. This effect of RACK1 is associated with its ability to enhance β-catenin stability and activate the canonical WNT signaling pathway in breast cancer cells. We identified PSMD2, a key component of the proteasome, as a novel binding partner for RACK1 and β-catenin. Interestingly, although there is no interaction between RACK1 and β-catenin, RACK1 binds PSMD2 competitively with β-catenin. Moreover, RACK1 prevents ubiquitinated β-catenin from binding to PSMD2, thereby protecting β-catenin from proteasomal degradation. Collectively, our findings uncover a novel mechanism by which RACK1 increases β-catenin stability and promotes breast cancer proliferation.

TRIM22 promotes the proliferation of glioblastoma cells by activating MAPK signaling and accelerating the degradation of Raf-1

The tripartite motif (TRIM) 22 and mitogen-activated protein kinase (MAPK) signaling pathways play critical roles in the growth of glioblastoma (GBM). However, the molecular mechanism underlying the relationship between TRIM22 and MAPK signaling remains unclear. Here, we found that TRIM22 binds to exon 2 of the sphingosine kinase 2 (SPHK2) gene. An ERK1/2-driven luciferase reporter construct identified TRIM22 as a potential activator of MAPK signaling. Knockout and overexpression of TRIM22 regulate the inhibition and activation of MAPK signaling through the RING-finger domain. TRIM22 binds to Raf-1, a negative regulator of MAPK signaling, and accelerates its degradation by inducing K48-linked ubiquitination, which is related to the CC and SPRY domains of TRIM22 and the C1D domain of Raf-1. In vitro and in vivo, an SPHK2 inhibitor (K145), an ERK1/2 inhibitor (selumetinib), and the nonphosphorylated mutant Raf-1S338A inhibited GBM growth. In addition, deletion of the RING domain and the nuclear localization sequence of TRIM22 significantly inhibited TRIM22-induced proliferation of GBM cells in vivo and in vitro. In conclusion, our study showed that TRIM22 regulates SPHK2 transcription and activates MAPK signaling through posttranslational modification of two critical regulators of MAPK signaling in GBM cells.

The roles and targeting options of TRIM family proteins in tumor

Tripartite motif (TRIM) containing proteins are a class of E3 ubiquitin ligases, which are critically implicated in the occurrence and development of tumors. They can function through regulating various aspects of tumors, such as tumor proliferation, metastasis, apoptosis and the development of drug resistance during tumor therapy. Some members of TRIM family proteins can mediate protein ubiquitination and chromosome translocation via modulating several signaling pathways, like p53, NF-κB, AKT, MAPK, Wnt/β-catenin and other molecular regulatory mechanisms. The multi-domain nature/multi-functional biological role of TRIMs implies that blocking just one function or one domain might not be sufficient to obtain the desired therapeutic outcome, therefore, a detailed and systematic understanding of the biological functions of the individual domains of TRIMs is required. This review mainly described their roles and underlying mechanisms in tumorigenesis and progression, and it might shade light on a potential targeting strategy for TRIMs in tumor treatment, especially using PROTACs.

Tripartite motif containing 63, regulated by E26 transformation specific variant 4, facilitates the thyroid carcinoma progression and the AKT, p38, and ERK signaling pathways

The current study aimed to investigate the role of tripartite motif containing 63 (TRIM63) in the progression of thyroid carcinomas. The results showed that TRIM63 was highly expressed in thyroid carcinomas tissues. TRIM63 knockdown inhibited the proliferation and induced the apoptosis of thyroid carcinoma cells, and overexpression of TRIM63 promoted the cell proliferation ability. These results were further confirmed by the in vivo growth of xenograft tumors. Subsequently, the underlying mechanism was explored. TRIM63 silencing repressed the AKT, p38, and ERK signaling pathways in thyroid carcinoma cells, and the contrary results were observed in TRIM63-upregulated thyroid carcinoma cells. Furthermore, we found that E26 transformation specific variant 4 (ETV4) regulated the transcription of TRIM63. The loss of TRIM63 reversed the ETV4 overexpression-induced promotion of proliferation in thyroid carcinomas cells. In conclusion, TRIM63, regulated by ETV4, activates the AKT, p38, and ERK signaling pathways and facilitates the thyroid carcinoma development.

Tripartite motif family proteins in inflammatory bowel disease: Mechanisms and potential for interventions

Inflammatory bowel disease (IBD) is a chronic recurrent gastrointestinal inflammatory disease that poses a heavy burden to the global healthcare system. However, the current paucity of mechanistic understanding of IBD pathogenesis hampers the development of aetiology‐directed therapies. Novel therapeutic options based on IBD pathogenesis are urgently needed for attaining better long‐term prognosis for IBD patients. The tripartite motif (TRIM) family is a large protein family including more than 70 structurally conservative members, typically characterized by their RBCC structure, which primarily function as E3 ubiquitin ligases in post‐translational modification. They have emerged as regulators of a broad range of cellular mechanisms, including proliferation, differentiation, transcription and immune regulation. TRIM family proteins are involved in multiple diseases, such as viral infection, cancer and autoimmune disorders, including inflammatory bowel disease. This review provides a comprehensive perspective on TRIM proteins' involvement in the pathophysiology and progression of IBD, in particular, on intestinal mucosal barriers, gene susceptibility and opportunistic infections, thus providing novel therapeutic targets for this complicated disease. However, the exact mechanisms of TRIM proteins in IBD pathogenesis and IBD‐related carcinogenesis are still unknown, and more studies are warranted to explore potential therapeutic targets of TRIM proteins in IBD.

TRIM45 causes neuronal damage by aggravating microglia-mediated neuroinflammation upon cerebral ischemia and reperfusion injury

Excessive and unresolved neuroinflammation is a key component of the pathological cascade in brain injuries such as ischemic stroke. Tripartite motif-containing 45 (TRIM45) is a ubiquitin E3 ligase involved in various critical biological processes. However, the role of TRIM45 in cerebral ischemia remains unknown. Here, we found that the TRIM45 protein was highly expressed in the peri-infarct areas of mice subjected to cerebral ischemia and reperfusion injury induced by middle cerebral artery occlusion. This study systemically evaluated the putative role of TRIM45 in the regulation of neuroinflammation during ischemic injury and the potential underlying mechanisms. We found that TRIM45 knockdown significantly decreased proinflammatory cytokine and chemokine production in primary cultured microglia challenged with oxygen-glucose deprivation and reoxygenation (OGD/R) treatment. Mechanistically, we demonstrated that TRIM45 constitutively interacted with TAB2 and consequently facilitated the Lys-63-linked polyubiquitination of TAB2, leading to the formation of the TAB1-TAK1-TAB2 complex and activation of TAK1, which was ultimately followed by activation of the nuclear factor-kappa B (NF-κB) signaling pathway. In an in vitro coculture Transwell system, downregulation of TRIM45 expression also inhibited the OGD/R-induced activation of microglia and alleviated neuronal apoptosis. More importantly, microglia-specific knockdown of TRIM45 in mice significantly reduced the infarct size, mitigated neurological deficit scores, and improved cognitive function after ischemic stroke. Taken together, our study reveals that the TRIM45-TAB2 axis is a crucial checkpoint that controls NF-κB signaling in microglia during cerebral ischemia and reperfusion injury. Therefore, targeting TRIM45 may be an attractive therapeutic strategy.

RNA-sequencing identifies differentially expressed genes in T helper 17 cells in peritoneal fluid of patients with endometriosis

Innate and adaptive immune factors play significant roles in the pathophysiology of endometriosis. T helper 17 (Th17) cells, a pro-inflammatory T cell subset, were considered to contribute to the progression of endometriosis lesions. However, the regulatory mechanisms of Th17 cells in endometriosis remain unidentified, partially due to the difficulty in recovering live Th17 cells from endometriosis patients. In this study, by flow cytometry analysis of a set of chemokine receptors including CXCR3, CCR4, CCR10, and CCR6, live RORγt-and-IL-17A-expressing Th17 cells were enriched from peritoneal fluid (PF) of patients with different stages of endometriosis for the first time, RNA-sequencing (RNA-Seq) of these PF Th17 cells revealed significantly up-regulated genes and down-regulated genes in stage I-II and stage III-IV endometriosis, compared with their counterparts in normal PF. In conclusion, this study provides a novel method to isolate live Th17 cells from endometriosis patients, unveils an array of differentially expressed genes in endometriosis Th17 cells, and offers valuable gene expression profile information for endometriosis clinical research.

TRIM proteins in fibrosis

Fibrosis is an outcome of tissue repair after different types of injuries. The homeostasis of extracellular matrix is broken, and excessive deposition occurs, affecting the normal function of tissues and organs, which could become prostrated in serious cases.Finding a suitable target to regulate the repair process and reduce the damage caused by fibrosis is a hot research topic at present. The TRIM family is number of one of the E3 ubiquitin ligase subfamilies and participates in various biological processes including intracellular signal transduction, apoptosis, autophagy, and immunity by regulating the ubiquitination of target proteins. For the past few years, the important role of TRIM in the occurrence and development of fibrosis has been gradually revealed. In this review, we focus on the recent emerging topics on TRIM proteins in the regulation of fibrosis, fibrosis-related cytokines and pathways.

Inhibition of PKC/MEK pathway suppresses β1-integrin and mitigates breast cancer cells proliferation

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PGE2 enhanced β1- integrin expression via EP1 receptor, PKC, MEK and NfҡB.

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FOXC2, E2F1 and survivin play a role in PGE2 mediated effect in MCF7 cells.

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PGE2 enhances breast cancer cell cycle through E2F1, FOXC2, survivin and β integrin.

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Biochemical mediators of PKC/MEK pathway could be considered as targets for breast cancer treatment.

Prostaglandin E2 (PGE2) and β1-integrin have been correlated with breast cancer, where both could enhance progression and metastasis. Protein kinase C (PKC) and MEK have played a vital role in breast cancer development. Our study was conducted to elucidate the effect of inhibition of E-prostanoid receptor 1 (EP1)/ PKC/ MEK/ β1-integrin pathway in mitigating breast cancer progression and to evaluate the role of the intermediate signals FOXC2, E2F1, NF-ҡB and survivin. MCF7 cells were treated with 17 -PT-PGE2, an EP1 agonist, for 24 h, and β1-integrin was measured. To MCF7 cells treated with 17-PT-PGE2, inhibitors of either EP1, MEK, PKC or NF-ҡB were added followed by measurement of β1-integrin gene expression and cell proliferation in each case. Addition of 17- PT-PGE2 to MCF7 cells showed enhancement of both cell proliferation, and cell cycle transition from G1 to S phase. In addition, activation of EP1 receptor increased β1-integrin expression. On the contrary, inhibition of EP1 receptor showed a decrease in the cell proliferation, β1-integrin expression and cells transition to S phase, but increased cell count in apoptotic phase. Selective inhibition of each of MEK, PKC, and NF-ҡB suppressed 17 -PT-PGE2-mediated β1-integrin expression as well as cell proliferation. Furthermore, FOXC2, phosphorylated NF-ҡB, E2F1, and survivin levels were upregulated with 17- PT-PGE2 and suppressed by MEK, PKC and NF-ҡB inhibitors. Targeting the biochemical mediators of PKC/MEK pathway may be of value in developing new chemical entities for cancer treatment.

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.

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.

Targeting the Ubiquitin System in Glioblastoma

Glioblastoma is the most common primary brain tumor in adults with poor overall outcome and 5-year survival of less than 5%. Treatment has not changed much in the last decade or so, with surgical resection and radio/chemotherapy being the main options. Glioblastoma is highly heterogeneous and frequently becomes treatment-resistant due to the ability of glioblastoma cells to adopt stem cell states facilitating tumor recurrence. Therefore, there is an urgent need for novel therapeutic strategies. The ubiquitin system, in particular E3 ubiquitin ligases and deubiquitinating enzymes, have emerged as a promising source of novel drug targets. In addition to conventional small molecule drug discovery approaches aimed at modulating enzyme activity, several new and exciting strategies are also being explored. Among these, PROteolysis TArgeting Chimeras (PROTACs) aim to harness the endogenous protein turnover machinery to direct therapeutically relevant targets, including previously considered "undruggable" ones, for proteasomal degradation. PROTAC and other strategies targeting the ubiquitin proteasome system offer new therapeutic avenues which will expand the drug development toolboxes for glioblastoma. This review will provide a comprehensive overview of E3 ubiquitin ligases and deubiquitinating enzymes in the context of glioblastoma and their involvement in core signaling pathways including EGFR, TGF-β, p53 and stemness-related pathways. Finally, we offer new insights into how these ubiquitin-dependent mechanisms could be exploited therapeutically for glioblastoma.

Clostridium difficile toxin B induces colonic inflammation through the TRIM46/DUSP1/MAPKs and NF-κB signalling pathway

Clostridium difficile (C. difficile) infection results in toxin-induced epithelial injury and marked colonic inflammation. Mitogen-activated protein kinase (MAPK) and NF-κB which regulated by MAP kinase phosphatase (MKP, also known as dual specificity phosphatases, DUSP) are fundamental signalling pathways that mediate multiple cellular processes. However, the regulation of DUSP/MAPKs and NF-κB pathway in C. difficile-induced colonic inflammation remains unclear. Here, we report that TcdB significantly inhibits cell viability and induces production of IL-1β and TNF-α and activation of MAPKs and NF-κB. An E3-ubiquitin ligase, TRIM46, ubiquitinates DUSP1, and its knockdown significantly inhibit TcdB-induced activation of MAPKs and NF-κB and production of IL-1β and TNF-α. Moreover, TRIM46 overexpression induced production of IL-1β and TNF-α also reversed by DUSP1 overexpression. We further found that promoter of TRIM46 also demonstrated binding to NF-κBp65, leading to regulate TRIM46 expression. In addition, the increased colonic inflammation induced by C. difficile administration was inhibited by TRIM46 knockdown in vivo. Taken together, the present study shows that TRIM46, as a new regulator of DUSP1/MAPKs and NF-κB signalling pathway, plays an important role in TcdB-induced colonic inflammation.

TRIM67 inhibits tumor proliferation and metastasis by mediating MAPK11 in Colorectal Cancer

Purpose: We recently reported that tripartite motif-containing 67 (TRIM67) activates p53 to suppress colorectal cancer (CRC). However, the function and mechanism of TRIM67 in the inhibition of CRC cell proliferation and metastasis remains to be further elucidated.

Methods: We detected the expression of TRIM67 in CRC tissues compared with normal tissues and confirmed its relationship with clinicopathological features. DNA methylation of TRIM67 was analyzed to determine its significantly hypermethylated sites in CRC tissues. CCK-8, colony formation, transwell migration, and Matrigel invasion assays were performed to evaluate the effects of TRIM67 on cell proliferation and metastasis in CRC cells. RNA sequencing of TRIM67 and TRIM67 rescue experiments were performed to reveal its mechanisms in CRC cell proliferation and metastasis.

Results:TRIM67 expression was significantly downregulated in CRC tissues and its expression was associated with clinical stage, invasive depth, tumor size, lymph node metastasis, and Dukes' stage. Three methylation sites were significantly hypermethylated and negatively correlated with TRIM67 expression in CRC tissues. TRIM67 suppressed proliferation, migration, and invasion in CRC cells. RNA sequencing revealed that protein mitogen-activated protein kinase 11 (MAPK11) was a potential downstream negative regulatory gene of TRIM67. Reversing MAPK11 expression could rescue the effects of TRIM67 on the proliferation and metastasis of CRC cells.

Conclusion:TRIM67 inhibited cell proliferation and metastasis by mediating MAPK11 in CRC, and may be a potential target to inhibit CRC metastasis.

Trim45 is essential to the development of the diencephalon and eye in zebrafish embryos

Trim45 is one of the RING (really interesting new gene) finger containing E3 ligase, which belongs to TRIM (Tripartite motif) protein family. Its molecular biological functions have been well characterized but not in light of developmental aspects. Here, we are reporting its expression patterns and developmental functions in zebrafish embryos. First, maternal transcripts of trim45 were found at one cell stage while its zygotic messages appeared at 30% epiboly. trim45 transcripts were restricted to the optical tectum, hypothalamus, hindbrain, and pharyngeal endoderm at 24 hpf (hour post-fertilization), and further to the retinal ganglion cell layer and cranial ganglion at 36 hpf. Second, ectopic expression of trim45 by injecting its mRNAs into embryos at one cell stage caused significant expansion of the diencephalon and eye fields at 24 hpf. In contrast, knock-down of trim45 with anti-sense trim45 morpholinos reduced the size of the two tissues at 24 hpf. Finally, the spatial distribution of the transcripts from olig2 and rx1/rx3, markers for the midbrain and eye respectively, were significantly decreased in the thalamus and eye fields respectively at 24 hpf. Based upon these observations, we proposed possible roles of Trim45 in the development of the diencephalon and eye in zebrafish embryos.

MicroRNA‑29c‑3p acts as a tumor suppressor gene and inhibits tumor progression in hepatocellular carcinoma by targeting TRIM31

Aberrant expression of microRNAs (miRNAs) has been widely reported in many malignant tumors, and dysregulated miRNAs play an important role in the malignant progression of tumors. It has been reported that miR-29c-3p expression is dysregulated in tumors and promotes the development of tumors, especially in hepatocellular carcinoma (HCC). However, the specific mechanism of miR-29c-3p in HCC is not clear. The present study demonstrated that miR-29c-3p was expressed at low levels in HCC patients and cell lines and that its decreased expression was closely related to poor prognosis of HCC patients. Overexpression of miR-29c-3p could significantly inhibit the proliferation and migration of HCC cells in vitro and suppress the HCC tumor growth in vivo. The luciferase reporter assay demonstrated that miR-29c-3p directly bound to tripartite motif containing 31 (TRIM31) and suppressed TRIM31 expression. Finally, upregulation of TRIM31 could partially abolish the tumor suppressing roles of miR-29c-3p in HCC. Overall, miR-29c-3p, as a tumor suppressor gene, was revealed to inhibit the malignant progression of HCC by reducing the expression of TRIM31 and may be used as a potential therapeutic target for the precise treatment of HCC.

RACK1 affects the progress of G2/M by regulating Aurora-A

Aurora-A is a serine/threonine kinase, which is overexpressed in multiple human cancers and plays a key role in tumorigenesis and tumor development. In this study, we found that the receptor of activated C-kinase1 (RACK1), an important regulator of biological functions, interacted with Aurora-A and co-localized with Aurora-A at centrosomes. Moreover, RACK1 induces the auto-phosphorylation of Aurora-A in vitro and in vivo. Depletion of RACK1 impaired the activation of Aurora-A in late G2 phase, then inhibited the mitotic entry and leaded to multi-polarity, severe chromosome alignment defects, or centrosome amplification. Taken together, these results suggest that RACK1 is a new partner of Aurora-A and play a critical role in the regulation of the Aurora-A activity during mitosis, which may provide a basis for future anticancer studies targeting Aurora-A.

UBN2 promotes tumor progression via the Ras/MAPK pathway and predicts poor prognosis in colorectal cancer

Background

Ubinuclein-2 (UBN2) is a nuclear protein that interacts with many transcription factors. The molecular role and mechanism of UBN2 in the development and progression of cancers, including colorectal cancer (CRC), is not well understood. The current study explored the role of UBN2 in the development and progression CRC.

Methods

Oncomine network and The Cancer Genome Atlas (TCGA) database were downloaded and Gene Set Enrichment Analysis (GSEA) was performed to compare the UBN2′s expression between normal and tumor tissues, as well as the potential correlation of UBN2 expression with signaling pathways. Immunohistochemistry (IHC), qRT-PCR and Western blotting were performed to determine the expression of UBN2 in CRC tissues or cell lines. In vitro proliferation and invasion assays, and orthotopic mouse metastatic model were used to analyze the effect of UBN2 on the development and progression of CRC.

Results

The analysis of UBN2 expression using Oncomine network showed that UBN2 was upregulated in CRC tissues compared to matched adjacent normal intestinal epithelial tissues. IHC, qRT-PCR and Western blotting confirmed that UBN2 expression is higher in CRC tissues compared with matched adjacent normal intestinal epithelial tissues. In addition, analyses of TCGA data revealed that high UBN2 expression was associated with advanced stages of lymph node metastasis, distant metastasis, and short survival time in CRC patients. IHC showed that high UBN2 expression is correlated with advanced stages of CRC. Moreover, UBN2 is highly expressed in the liver metastatic lesions. Furthermore, knockdown of UBN2 inhibited the growth, invasiveness and metastasis of CRC cells via regulation of the Ras/MAPK signaling pathway.

Conclusion

The current study demonstrates that UBN2 promotes tumor progression in CRC. UBN2 may be used as a promising biomarker for predicting the prognosis of CRC patients.

Electronic supplementary material

The online version of this article (10.1186/s12935-019-0848-4) contains supplementary material, which is available to authorized users.

Short-term exposure to fine particulate air pollution and genome-wide DNA methylation: A randomized, double-blind, crossover trial

BACKGROUND

Previous studies have associated fine particulate (PM_2.5) exposure with changes in gene-specific DNA methylation. However, the evidence was still limited and inconsistent in genome-wide DNA methylation.

OBJECTIVE

To examine the impact of short-term PM_2.5 exposure on genome-wide DNA methylation.

METHODS

We designed a randomized, double-blind, crossover trial among 36 healthy young adults in Shanghai, China. A two-stage intervention with alternative use of real and sham air purifiers in dormitory rooms for consecutive 9 days were conducted to create natural low and high exposure scenarios of PM_2.5. Blood genome-wide DNA methylation was analyzed using the Illumina Infinium Human Methylation EPIC BeadChip (850k). Mixed-effect models were used to evaluate the impacts of changes in PM_2.5 levels on genome-wide DNA methylation.

RESULTS

There was a drastic contrast for PM_2.5 exposure levels in the two scenarios (24-h averages: 53.1 and 24.3 μg/m³). Between the high and low exposure groups, methylation levels were changed significantly with a false discovery rate < 0.01 at 49 CpG loci, of which 31 CpG sites were annotated to the specific genes. DNA methylation of these annotated genes were elevated in response to increased PM_2.5 exposure, which were implicated in insulin resistance, glucose and lipid metabolism, inflammation, oxidative stress, platelet activation, and cell survival and apoptosis.

CONCLUSIONS

Our results provided novel biological pathways linking ambient PM_2.5 exposure to systemic adverse response through variations in DNA methylation and reinforced the hypothesized role of epigenetics in the development of cardiometabolic diseases induced by PM_2.5 exposure.

RAB40C regulates RACK1 stability via the ubiquitin-proteasome system

AIM

RACK1 is a multifunctional scaffolding protein that is expressed in many cellular compartments, orchestrating a number of signaling processes. RACK1 acts as a signaling hub to localize active enzymes to discrete locations; therefore tight control of RACK1 is vital to cellular homeostasis. Our aim was to identify the mechanisms responsible for RACK1 turnover and show that degradation is directed by the ubiquitin proteasome system.

RESULTS

Using siRNA screening, we identified RAB40C as the ubiquitin E3 ligase responsible for ubiquitination of RACK1, and that the action of RAB40C in controlling RACK1 levels is crucial to both cancer cell growth and migration of T cells.

CONCLUSION

Our data suggest that manipulation of RACK1 levels in this way may provide a novel strategy to explore RACK1 function.

MicroRNA‑122 acts as tumor suppressor by targeting TRIM29 and blocking the activity of PI3K/AKT signaling in nasopharyngeal carcinoma in vitro

Nasopharyngeal carcinoma (NPC) is endemic in the southern provinces of China and Southeast Asia. It has been reported that microRNA-122 (miR-122) and tripartite motif-containing protein 29 (TRIM29) serve important roles in many types of tumor. The present study aimed to evaluate the expression of miR-122 and TRIM29, and their clinical significance in NPC, and to examine the associated molecular mechanisms. It was observed that low expression of miR-122 and high expression of TRIM29 led to a low overall survival rate in patients with NPC, which was associated with tumor-node-metastasis (TNM) stage and distant metastasis of NPC. Low expression of miR-122 was correlated reciprocally with high expression of TRIM29 in NPC tissues, and the two were aggravated by radiation treatment in NPC cell lines. Through Cell Counting kit-8 and Transwell assays, miR-122 was demonstrated to be able to inhibit the proliferation, migration and invasion of NPC cells. Through reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analyses, the expression of metastasis-associated genes, including E-cadherin, metastatic tumor antigen 1, matrix metalloproteinase-2 and metalloproteinase inhibitor 2 were demonstrated to be regulated by miR-122 in NPC cells. Additionally, through a luciferase assay, RT-qPCR and western blot analysis, it was demonstrated that TRIM29 may be a direct target of miR-122. In addition, it was noted that miR-122 decreased the expression of phosphorylated (p) phosphatidylinositol 3-kinase (PI3K) and p-RAC-α serine/threonine-protein kinase (AKT). Collectively, the results of the present study demonstrated that miR-122 may exert its tumor suppressive role by targeting TRIM29 and inhibiting the activity of PI3K/AKT signaling. It was indicated that miR-122 and TRIM29 may be developed as biomarkers of NPC, and possible molecular targets for the prevention of metastasis in patients with NPC.

TRIM29 overexpression is associated with poor prognosis and promotes tumor progression by activating Wnt/β-catenin pathway in cervical cancer

Dysregulation of TRIM29 has been reported to be involved in tumorigenesis, but the role of TRIM29 in cervical cancer is unclear. In this study, we first examined TRIM29 expression and found that TRIM29 mRNA and protein expression was upregulated in cervical cancer tissues when compared with the matched adjacent cervical tissues. We further detected TRIM29 protein with immunohistochemistry in 150 paraffin-embedded samples from early-stage cervical cancer patients. The results showed that high expression of TRIM29 was significantly associated with pelvic lymph node metastasis (p=0.002), advanced FIGO stage (p=0.026) and post-operative recurrence (p<0.001). Patients with high expression of TRIM29 had a shorter overall survival (HR 5.042, p<0.001) and disease-free survival (HR 4.260, p<0.001). TRIM29 was proven to be an independent prognostic factor for cervical cancer patients. When endogenous TRIM29 expression was knocked down by siRNAs, cell proliferation, colony formation, migration and invasion in cervical cancer cell lines HeLa and SiHa were obviously inhibited. Meanwhile, TRIM29 knockdown increased E-cadherin expression but decreased the expression of N-cadherin and β-Catenin, which indicated that TRIM29 could promote epithelial-mesenchymal transition (EMT). Mechanically, knockdown of TRIM29 enhanced GSK-3β protein expression and inhibited the expression of β-Catenin and C-myc proteins. GSK-3β is a key upstream suppressor of β-Catenin and c-myc expression is an indicator of Wnt/β-Catenin activity. Therefore, these results demonstrate that TRIM29 promotes tumor progression by activating Wnt/β-Catenin signaling. In conclusion, TRIM29 is overexpressed and associated with survival of early-stage cervical cancer, indicating that TRIM29 may be a potential prognostic biomarker and therapeutic target for cervical cancer.

High expression of RACK1 is associated with poor prognosis in patients with pancreatic ductal adenocarcinoma

Receptor for activated C kinase 1 (RACK1) is associated with certain aspects of cancer biology and signaling pathways, but its function in pancreatic ductal adenocarcinoma (PDAC) remains unknown. In the present study, 157 patients with PDAC were enrolled. RACK1 mRNA and protein expression levels were analyzed in PDAC tissues and matched adjacent noncancerous tissues by reverse transcription-quantitative polymerase chain reaction and western blotting. RACK1 expression levels in paraffin-embedded PDAC tissues were determined by immunohistochemistry. The associations between RACK1 expression and clinical data were evaluated using χ² analysis. The relationship between RACK1 expression and the survival data of patients was analyzed using Kaplan-Meier and log rank tests. RACK1 mRNA and protein were revealed to be overexpressed in PDAC tumor tissues compared with adjacent noncancerous tissues. RACK1 expression was associated with clinical stage (P=0.001), lymph node invasion (P=0.003) and liver metastasis (P=0.001). Furthermore, patients with PDAC and high RACK1 expression demonstrated shorter overall survival times compared with patients with low RACK1 expression (P=0.002). Multivariate analysis indicated that RACK1 overexpression was an independent prognostic factor for patients with PDAC. Overexpression of RACK1 may contribute to tumor progression, and may be a potential prognostic biomarker for patients with PDAC.

TRIM45 functions as a tumor suppressor in the brain via its E3 ligase activity by stabilizing p53 through K63-linked ubiquitination

Tripartite motif-containing protein 45 (TRIM45) belongs to a large family of RING-finger-containing E3 ligases, which are highly expressed in the brain. However, little is known regarding the role of TRIM45 in cancer biology, especially in human glioma. Here, we report that TRIM45 expression is significantly reduced in glioma tissue samples. Overexpression of TRIM45 suppresses proliferation and tumorigenicity in glioblastoma cells in vitro and in vivo. In addition, CRISPR/Cas9-mediated knockout of TRIM45 promotes proliferation and inhibits apoptosis in glioblastoma cells. Further mechanistic analyses show that TRIM45 interacts with and stabilizes p53. TRIM45 conjugates K63-linked polyubiquitin chain to the C-terminal six lysine residues of p53, thereby inhibiting the availability of these residues to the K48-linked polyubiquitination that targets p53 for degradation. These findings suggest that TRIM45 is a novel tumor suppressor that stabilizes and activates p53 in glioma.

The pineal gland: A model for adrenergic modulation of ubiquitin ligases

INTRODUCTION

A recent study of the pineal gland of the rat found that the expression of more than 3000 genes showed significant day/night variations (The Hartley dataset). The investigators of this report made available a supplemental table in which they tabulated the expression of many genes that they did not discuss, including those coding for components of the ubiquitin proteasome system. Herein we identify the genes of the ubiquitin proteasome system whose expression were significantly influenced by environmental lighting in the Hartley dataset, those that were stimulated by DBcAMP in pineal glands in culture, and those that were stimulated by norepinephrine.

PURPOSE

Using the Ubiquitin and Ubiquitin-like Conjugation Database (UUCA) we identified ubiquitin ligases and conjugases, and deubiquitinases in the Hartley dataset for the purpose of determining whether expression of genes of the ubiquitin proteasome pathway were significantly influenced by day/night variations and if these variations were regulated by autonomic innervation of the pineal gland from the superior cervical ganglia.

METHODS

In the Hartley experiments pineal glands groups of rats sacrificed during the day and groups sacrificed during the night were examined for gene expression. Additional groups of rats had their superior cervical ganglia removed surgically or surgically decentralized and the pineal glands likewise examined for gene expression.

RESULTS

The genes with at least a 2-fold day/night significant difference in expression included genes for 5 ubiquitin conjugating enzymes, genes for 58 ubiquitin E3 ligases and genes for 6 deubiquitinases. A 35-fold day/night difference was noted in the expression of the gene Sik1, which codes for a protein containing both an ubiquitin binding domain (UBD) and an ubiquitin-associated (UBA) domain. Most of the significant differences in these genes were prevented by surgical removal, or disconnection, of the superior cervical ganglia, and most were responsive, in vitro, to treatment with a cyclic AMP analog, and norepinephrine. All previously described 24-hour rhythms in the pineal require an intact sympathetic input from the superior cervical ganglia.

CONCLUSIONS

The Hartley dataset thus provides evidence that the pineal gland is a highly useful model for studying adrenergically dependent mechanisms regulating variations in ubiquitin ligases, ubiquitin conjugases, and deubiquitinases, mechanisms that may be physiologically relevant not only in the pineal gland, but in all adrenergically innervated tissue.

Cyclooxygenase-2 induced β1-integrin expression in NSCLC and promoted cell invasion via the EP1/MAPK/E2F-1/FoxC2 signal pathway

Cyclooxygenase-2 (COX-2) has been implicated in cell invasion in non-small-cell lung cancer (NSCLC). However, the mechanism is unclear. The present study investigated the effect of COX-2 on β1-integrin expression and cell invasion in NSCLC. COX-2 and β1-integrin were co-expressed in NSCLC tissues. COX-2 overexpression or Prostaglandin E2 (PGE2) treatment increased β1-integrin expression in NSCLC cell lines. β1-integrin silencing suppressed COX-2-mediated tumour growth and cancer cell invasion in vivo and in vitro. Prostaglandin E Receptor EP1 transfection or treatment with EP1 agonist mimicked the effect of PGE₂ treatment. EP1 siRNA blocked PGE₂-mediated β1-integrin expression. EP1 agonist treatment promoted Erk1/2, p38 phosphorylation and E2F-1 expression. MEK1/2 and p38 inhibitors suppressed EP1-mediated β1-integrin expression. E2F-1 silencing suppressed EP1-mediated FoxC2 and β1-integrin upregulation. ChIP and Luciferase Reporter assays identified that EP1 agonist treatment induced E2F-1 binding to FoxC2 promotor directly and improved FoxC2 transcription. FoxC2 siRNA suppressed β1-integrin expression and EP1-mediated cell invasion. Immunohistochemistry showed E2F-1, FoxC2, and EP1R were all highly expressed in the NSCLC cases. This study suggested that COX-2 upregulates β1-integrin expression and cell invasion in NSCLC by activating the MAPK/E2F-1 signalling pathway. Targeting the COX-2/EP1/PKC/MAPK/E2F-1/FoxC2/β1-integrin pathway might represent a new therapeutic strategy for the prevention and treatment of this cancer.