Sal-like 4 protein levels in breast cancer cells are post-translationally down-regulated by tripartite motif-containing 21

[TRIM21 Inhibits the Proliferation and Migration of Lung Adenocarcinoma Cells by Interacting with ZSWIM1]

BACKGROUND

Lung adenocarcinoma (LUAD) is a highly morbid and fatal cancer. Despite advancements in modern medical treatment, the 5-year survival rate of patients remains suboptimal. Our previous study revealed that zinc finger SWIM-type containing 1 (ZSWIM1), a novel protein, promotes the proliferation, migration, and invasion of LUAD cells. The aim of this study is to investigate the impact of E3 ubiquitin ligase tripartite motif protein 21 (TRIM21) on ZSWIM1-mediated cell proliferation and migration.

METHODS

The interaction and co-localization between TRIM21 and ZSWIM1 were verified using co-immunoprecipitation (Co-IP) and immunofluorescence (IF). The effects of TRIM21 and ZSWIM1 on the proliferation and migration of LUAD cells were assessed through MTT and Transwell assays, respectively. Western blot (WB) analysis was conducted to evaluate the impact of TRIM21 and ZSWIM1 on the expression of epithelial-mesenchymal transition (EMT) markers in LUAD cells. The influence of TRIM21 on the ubiquitination of ZSWIM1 was examined using Co-IP combined with WB.

RESULTS

TRIM21 was found to interact and co-localize with ZSWIM1. Overexpression of TRIM21 inhibited the proliferation and migration of LUAD cells. Overexpression of TRIM21 reduced the promoting effect of ZSWIM1 on the proliferation, migration, and invasion of lung adenocarcinoma cells, and reversed the impact of ZSWIM1 on the expression of E-cadherin and Vimentin. Conversely, knockdown of TRIM21 further enhanced the promoting effect of ZSWIM1 on the proliferation and migration of LUAD cells. Mechanistically, we observed that overexpression of TRIM21 significantly enhanced the ubiquitination level of ZSWIM1, leading to a decrease in ZSWIM1 protein expression.

CONCLUSIONS

TRIM21 binds to and promotes the ubiquitination of ZSWIM1, resulting in reduced protein expression of ZSWIM1, which leads to the inhibition of ZSWIM1-mediated promotion of proliferation, migration, and invasion in LUAD cells.

The interconnected roles of TRIM21/Ro52 in systemic lupus erythematosus, primary Sjögren's syndrome, cancers, and cancer metabolism

Protein tripartite motif-containing 21 (TRIM21/Ro52), an E3 ubiquitin ligase, is an essential regulator of innate immunity, and its dysregulation is closely associated with the development of autoimmune diseases, predominantly systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (pSS). TRIM21 /Ro52 also features anti-cancer and carcinogenic functions according to different malignancies. The interconnected role of TRIM21/Ro52 in regulating autoimmunity and cell metabolism in autoimmune diseases and malignancies is implicated. In this review, we summarize current findings on how TRIM21/Ro52 affects inflammation and tumorigenesis, and investigate the relationship between TRIM21/Ro52 expression and the formation of lymphoma and breast cancer in SLE and pSS populations.

TRIM proteins in breast cancer: Function and mechanism

Breast cancer is the most prevalent malignancy in the world, and despite tremendous progress in current treatment strategies, recurrence, metastasis and drug resistance of breast cancer remain the major causes of death in patients. Tripartite motif (TRIM) family proteins play a critical role in the tumor progression such as cell proliferation, migration, invasion, and metastasis. Accumulating evidence suggests that the TRIM protein family serve as cancer suppressor proteins or oncoproteins in breast cancer. This review focused on the roles and molecular mechanisms of TRIM protein in breast cancer. Importantly, it provides new insights that TRIM proteins may be ideal targets to treat breast cancer.

Proteolytic regulation of CD73 by TRIM21 orchestrates tumor immunogenicity

Despite the rapid utilization of immunotherapy, emerging challenges to the current immune checkpoint blockade need to be resolved. Here, we report that elevation of CD73 levels due to its aberrant turnover is correlated with poor prognosis in immune-cold triple-negative breast cancers (TNBCs). We have identified TRIM21 as an E3 ligase that governs CD73 destruction. Disruption of TRIM21 stabilizes CD73 that in turn enhances CD73-catalyzed production of adenosine, resulting in the suppression of CD8+ T cell function. Replacement of lysine 133, 208, 262, and 321 residues by arginine on CD73 attenuated CD73 ubiquitylation and degradation. Diminishing of CD73 ubiquitylation remarkably promotes tumor growth and impedes antitumor immunity. In addition, a TRIM21high/CD73low signature in a subgroup of human breast malignancies was associated with a favorable immune profile. Collectively, our findings uncover a mechanism that governs CD73 proteolysis and point to a new therapeutic strategy by modulating CD73 ubiquitylation.

Altered Expression of TRIM Proteins - Inimical Outcome and Inimitable Oncogenic Function in Breast Cancer with Diverse Carcinogenic Hallmarks

Deregulation of ubiquitin-mediated degradation of oncogene products or tumor suppressors appears to be implicated in the genesis of carcinomas, according to new clinical findings. Conferring to recent research, some members of the tripartite motif (TRIM) proteins (a subfamily of the RING type E3 ubiquitin ligases) act as significant carcinogenesis regulators. Intracellular signaling, development, apoptosis, protein quality control, innate immunity, autophagy, and carcinogenesis are all regulated by TRIM family proteins, the majority of which have E3 ubiquitin ligase activity. The expression of TRIMs in tumors is likely to be related to the formation and/or progression of the disease, and TRIM expression could be used to predict cancer prognosis. Breast cancer is the most common malignancy in women and also the leading cause of death. TRIM family proteins have unique, vital activities, and their dysregulation, such as TRIM 21, promotes breast cancer, according to growing evidence. Many TRIM proteins have been identified as important cancer biomarkers, with decreased or elevated levels of expression. TRIM29 functions as a hypoxia-induced tumor suppressor gene, revealing a new molecular mechanism for ATM-dependent breast cancer suppression. In breast cancer cells, the TRIM28-TWIST1-EMT axis exists, and TRIM28 enhances breast cancer metastasis by stabilizing TWIST1, and thereby increasing epithelial-tomesenchymal transition. Interestingly, many TRIM proteins are involved in the control of p53, and many TRIM proteins are likewise regulated by p53, according to current research. Furthermore, TRIMs linked to specific tumors may aid in the creation of innovative TRIM-targeted cancer treatments. This review focuses on TRIM proteins that are involved in tumor development, progression, and are of clinical significance in breast cancer.

Targeting CSC-related transcription factors by E3 ubiquitin ligases for cancer therapy

Evidence has revealed that transcription factors play essential roles in regulation of multiple cellular processes, including cell proliferation, metastasis, EMT, cancer stem cells and chemoresistance. Dysregulated expression levels of transcription factors contribute to tumorigenesis and malignant progression. The expression of transcription factors is tightly governed by several signaling pathways, noncoding RNAs and E3 ubiquitin ligases. Cancer stem cells (CSCs) have been validated in regulation of tumor metastasis, reoccurrence and chemoresistance in human cancer. Transcription factors have been verified to participate in regulation of CSC formation, including Oct4, SOX2, KLF4, c-Myc, Nanog, GATA, SALL4, Bmi-1, OLIG2, POU3F2 and FOX proteins. In this review article, we will describe the critical role of CSC-related transcription factors. We will further discuss which E3 ligases regulate the degradation of these CSC-related transcription factors and their underlying mechanisms. We also mentioned the functions and mechanisms of EMT-associated transcription factors such as ZEB1, ZEB2, Snail, Slug, Twist1 and Twist2. Furthermore, we highlight the therapeutic potential via targeting E3 ubiquitin ligases for modulation of these transcription factors.

The emerging roles of TRIM21 in coordinating cancer metabolism, immunity and cancer treatment

Tripartite motif containing-21 (TRIM21), an E3 ubiquitin ligase, was initially found to be involved in antiviral responses and autoimmune diseases. Recently studies have reported that TRIM21 plays a dual role in cancer promoting and suppressing in the occurrence and development of various cancers. Despite the fact that TRIM21 has effects on multiple metabolic processes, inflammatory responses and the efficacy of tumor therapy, there has been no systematic review of these topics. Herein, we discuss the emerging role and function of TRIM21 in cancer metabolism, immunity, especially the immune response to inflammation associated with tumorigenesis, and also the cancer treatment, hoping to shine a light on the great potential of targeting TRIM21 as a therapeutic target.

CDK7/GRP78 signaling axis contributes to tumor growth and metastasis in osteosarcoma

Osteosarcoma derives from primitive bone-forming mesenchymal cells and is the most common primary bone malignancy. Therapeutic targeting of osteosarcoma has been unsuccessful; therefore, identifying novel osteosarcoma pathogenesis could offer new therapeutic options. CDK7 is a subunit within the general transcription factor TFIIH. We aim to explore the new mechanism by which CDK7 regulates osteosarcoma and our studies may provide new theoretical support for the use of CDK7 inhibitors in the treatment of osteosarcoma. Here, we investigate the molecular mechanism underlying the association between CDK7 and GRP78 in osteosarcoma. Specifically, we find that an E3 ubiquitin ligase TRIM21 binds and targets GRP78 for ubiquitination and degradation, whereas CDK7 phosphorylates GRP78 at T69 to inhibit TRIM21 recruitment, leading to GRP78 stabilization. Notably, a CDK7-specific inhibitor, THZ1, blunts osteosarcoma growth and metastasis. Combination treatment with CDK7 and GRP78 inhibitors yield additive effects on osteosarcoma growth and progression inhibition. Thus, simultaneous suppression of CDK7 and GRP78 activity represents a potential new approach for the treatment of osteosarcoma. In conclusion, the discovery of this previously unknown CDK7/GRP78 signaling axis provides the molecular basis and the rationale to target human osteosarcoma.

SALL4 Oncogenic Function in Cancers: Mechanisms and Therapeutic Relevance

SALL4, a member of the SALL family, is an embryonic stem cell regulator involved in self-renewal and pluripotency. Recently, SALL4 overexpression was found in malignant cancers, including lung cancer, hepatocellular carcinoma, breast cancer, gastric cancer, colorectal cancer, osteosarcoma, acute myeloid leukemia, ovarian cancer, and glioma. This review updates recent advances of our knowledge of the biology of SALL4 with a focus on its mechanisms and regulatory functions in tumors and human hematopoiesis. SALL4 overexpression promotes proliferation, development, invasion, and migration in cancers through activation of the Wnt/β-catenin, PI3K/AKT, and Notch signaling pathways; expression of mitochondrial oxidative phosphorylation genes; and inhibition of the expression of the Bcl-2 family, caspase-related proteins, and death receptors. Additionally, SALL4 regulates tumor progression correlated with the immune microenvironment involved in the TNF family and gene expression through epigenetic mechanisms, consequently affecting hematopoiesis. Therefore, SALL4 plays a critical oncogenic role in gene transcription and tumor growth. However, there are still some scientific hypotheses to be tested regarding whether SALL4 is a therapeutic target, such as different tumor microenvironments and drug resistance. Thus, an in-depth understanding and study of the functions and mechanisms of SALL4 in cancer may help develop novel strategies for cancer therapy.

TRIM21 suppresses CHK1 activation by preferentially targeting CLASPIN for K63-linked ubiquitination

Expression of the E3 ligase TRIM21 is increased in a broad spectrum of cancers; however, the functionally relevant molecular pathway targeted by TRIM21 overexpression remains largely unknown. Here, we show that TRIM21 directly interacts with and ubiquitinates CLASPIN, a mediator for ATR-dependent CHK1 activation. TRIM21-mediated K63-linked ubiquitination of CLASPIN counteracts the K6-linked ubiquitination of CLASPIN which is essential for its interaction with TIPIN and subsequent chromatin loading. We further show that overexpression of TRIM21, but not a TRIM21 catalytically inactive mutant, compromises CHK1 activation, leading to replication fork instability and tumorigenesis. Our findings demonstrate that TRIM21 suppresses CHK1 activation by preferentially targeting CLASPIN for K63-linked ubiquitination, providing a potential target for cancer therapy.

A pan-cancer study of spalt-like transcription factors 1/2/3/4 as therapeutic targets

Spalt-like transcription factors (SALLs) are evolutionarily conserved proteins that participate in embryonic development. Four members of the SALL family, SALL1, SALL2, SALL3, and SALL4, are involved in cellular apoptosis, angiogenesis, invasion, and metastasis of tumors. We used the TCGA pan-cancer data to conduct a comprehensive analysis of SALL genes. High heterogeneity in the expression of these genes was observed across various cancers, SALL1 and SALL2 were downregulated, whereas SALL4 was upregulated. Moreover, we verified that SALL4 was commonly associated with survival disadvantage, whereas others were linked to a better prognosis. In renal cancer, SALL1, SALL2, and SALL3 showed downregulation, suggesting that they acted as tumor suppressors. Furthermore, SALLs were associated with immune infiltrate subtypes, with a close association between different degrees of infiltration of stromal cells and immune cells. DNA and RNA analyses in different tumors suggested different degrees of negative or positive correlation with tumor stem cell-like features. Finally, we revealed that SALLs were related to cancer cell resistance. Our results highlight the necessity to further study each SALL gene as a separate entity in specific types of cancer. Although this article showed that SALLs could be promising targets for cancer therapy, it needs further studies to validate the findings.

Manuscript Title: Analysis of tripartite motif (TRIM) family gene expression in prostate cancer bone metastases

Tripartite motif (TRIM) family proteins are post-translational protein modifiers with E3-ubiquitin ligase activity, thereby involved in various biological processes. The molecular mechanisms driving prostate cancer (PCa) bone metastasis (BM) are incompletely understood, and targetable genetic alterations are lacking in the majority of cases. Therefore, we aimed to explore the expression and potential functional relevance of 71 TRIM members in bone metastatic PCa. We performed transcriptome analysis of all human TRIM family members and 770 cancer-related genes in 29 localized PCa and 30 PCa BM using Nanostring. KEGG, STRING and Ubibrowser were used for further bioinformatic gene correlation and pathway enrichment analyses. Compared to localized tumors, six TRIMs are under-expressed while nine TRIMs are over-expressed in BM. The differentially expressed TRIM proteins are linked to TNF-, TGFβ-, PI3K/AKT- and HIF-1-signaling, and to features such as proteoglycans, platelet activation, adhesion and ECM-interaction based on correlation to cancer-related genes. The identification of TRIM-specific E3-ligase-substrates revealed insight into functional connections to oncogenes, tumor suppressors and cancer-related pathways including androgen receptor- and TGFβ signaling, cell cycle regulation and splicing. In summary, this is the first study that comprehensively and systematically characterizes the expression of all TRIM members in PCa BM. Our results describe post-translational protein modification as an important regulatory mechanism of oncogenes, tumor suppressors, and pathway molecules in PCa progression. Therefore, this study may provide evidence for novel therapeutic targets, in particular for the treatment or prevention of BM.

Anesthetic Propofol Promotes Tumor Metastasis in Lungs via GABAA R-Dependent TRIM21 Modulation of Src Expression

Generation of circulating tumor cells (CTCs), a key step in tumor metastasis, occurs during surgical tumor resection, often performed under general anesthesia. Propofol is the commonly used anesthetic, but its effects on CTCs and tumor metastasis remain largely unknown. Propofol effects are investigated in an experimental metastasis model by injecting tumor cells and, subsequently, low- or standard-dose propofol to nude mice through tail vein. Propofol- or vehicle-treated tumor cells are also injected to the mice. An in vitro tumor cell-vascular endothelial cell adhesion assay, immunofluorescence, and other methods are employed to assess how propofol affects tumor cell adhesion and extension. Propofol induces more lung tumor metastasis in mice than control. Mechanistically, propofol enhances tumor cell adhesion and extension through GABAA R to downregulate TRIM21 expression, leading to upregulation of Src, a protein associated with cell adhesion. These results demonstrate that propofol may promote tumor metastasis through GABAA R-TRIM21-Src mechanism.

Opposing roles of E3 ligases TRIM23 and TRIM21 in regulation of ion channel ANO1 protein levels

Anoctamin-1 (ANO1) (TMEM16A) is a calcium-activated chloride channel that plays critical roles in diverse physiological processes, such as sensory transduction and epithelial secretion. ANO1 levels have been shown to be altered under physiological and pathological conditions, although the molecular mechanisms that control ANO1 protein levels remain unclear. The ubiquitin–proteasome system is known to regulate the levels of numerous ion channels, but little information is available regarding whether and how ubiquitination regulates levels of ANO1. Here, we showed that two E3 ligases, TRIM23 and TRIM21, physically interact with the C terminus of ANO1. In vitro and in vivo assays demonstrated that whereas TRIM23 ubiquitinated ANO1 leading to its stabilization, TRIM21 ubiquitinated ANO1 and induced its degradation. Notably, ANO1 regulation by TRIM23 and TRIM21 is involved in chemical-induced pain sensation, salivary secretion, and heart-rate control in mice, and TRIM23 also mediates ANO1 upregulation induced by epidermal growth factor treatment. Our results suggest that these two antagonistic E3 ligases act together to control ANO1 expression and function. Our findings reveal a previously unrecognized mechanism for regulating ANO1 protein levels and identify a potential molecular link between ANO1 regulation, epidermal growth factor, and other signaling pathways.

Presence of anti-TIF-1γ, anti-Ro52, anti-SSA/Ro60 and anti-Su/Ago2 antibodies in breast cancer: a cross-sectional study

OBJECTIVES

The presence of myositis-specific antibodies (MSA), was recently reported in healthy individuals, cancer patients without myopathy and paraneoplastic rheumatic syndromes. We sought to analyze the frequency of MSA, myositis-associated antibodies (MAA) and autoantibodies related to systemic autoimmune rheumatic diseases (SARD) in breast cancer patients.

METHODS

One hundred fifty-two breast cancer patients were enrolled in a cross-sectional study. Clinical information was collected, and autoantibodies tested by immunoprecipitation of an ³⁵S-methionine-labeled K562 cell extract, enzyme-linked immunosorbent assay (ELISA) and Western blot when indicated. All statistical tests were performed using the software statistical package for the social science (SPSS) ver. 19.0 (IBM Inc., NYSE, USA).

RESULTS

Autoantibodies associated with SARD: anti-52 kD ribonucleoprotein/tripartite motif-containing 21 (anti-Ro52/TRIM21) was found in 5.9% (9/152), anti-Sjögren syndrome-related antigen A/60 kD ribonucleoprotein antibody (anti-SSA/Ro60) in 3.9% (6/152) and anti-Su antigen/Argonaute 2 antibody (anti-Su/Ago2) in 2.6% (4/152). Meanwhile, anti-transcription intermediary factor-1γ (anti-TIF-1γ, p155/140) antibody was positive in 2 cases and anti-polymyositis/scleroderma antibody was detected in one case. As a whole, 14.47% (22/152) of breast cancer patients showed autoantibodies associated with SARD. These specific autoantibodies were not associated with the presence of rheumatic diseases except one rheumatoid arthritis patient positive for anti-Ro52/TRIM21.

CONCLUSIONS

Autoantibodies to TIF-1γ were found in two patients with breast cancer without dermatomyositis (DM). More common specificities were autoantibodies anti-SSA/Ro60, anti-Ro52/TRIM21 and anti-Su/Ago2. More studies are needed in order to establish the biological meaning of the presence of SARD-associated autoantibodies in breast cancer.

TRIM21 - A potential novel therapeutic target in cancer

Tripartite motif-containing protein 21 (TRIM21) is well known to be involved in innate immunity, systemic lupus erythematosus and Sjögren's syndrome. In addition, TRIM21 involvement in cancer proliferation has been observed. However, the clinical significance of TRIM21 and its role in cancer cell proliferation and suppression remains elusive. Here we discuss the effects of TRIM21 on major cancer promoting proteins such as NF-κB, STAT3, BCL2, p53, p27 and Snail, comparing its signaling pathways under normal conditions and in the presence of a variety of carcinogenesis effectors (oncogenic, genotoxic and UV irradiation). Depending on the cancer type and the carcinogenesis effector, TRIM21 may enhance cancer proliferation, or alternatively it may increase the ubiquitination of many cancer-triggering proteins, resulting in their proteasomal degradation. This indicates the importance of TRIM21 in cancer proliferation and/or apoptosis and suggests its potential as a novel cancer therapeutic target.

Spalt-like transcription factor 4 expression in oral epithelial dysplasia and oral squamous cell carcinoma: An immunohistochemical appraisal

BACKGROUND:

Spalt-like transcription factor 4 (SALL4) is a stem cell marker that plays a critical role in maintaining the pluripotency and self-renewal of embryonic and hematopoietic stem cells. Only a few studies have been done to apprehend the expression of SALL4 in the potentially malignant oral lesion (leukoplakia with dysplasia) and oral squamous cell carcinoma (OSCC).

AIM:

The aim of this study is to evaluate the expression of SALL4 in leukoplakia with dysplasia and OSCC and to correlate the expression of the marker (SALL4) with the various clinicopathological parameters and patient outcome.

MATERIALS AND METHODS:

Immunohistochemistry for SALL4 protein was performed on 140 cases: those histopathologically confirmed cases of leukoplakia with dysplasia (n = 30) and OSCC (n = 110). Ten cases of nonepithelial neoplasm (fibroepithelial hyperplasia and excised tissue surrounding impacted third molars) were taken as control. Statistical analyses were applied to evaluate correlations between SALL4 overexpression and clinicopathological features of leukoplakia and OSCC. Survival rates were analyzed using Kaplan–Meier method.

RESULTS:

SALL4 positivity was observed to be higher (P = 0.001) in the tumor cells of OSCC with Immuno Reactive Score (IRS) ranging from 0 to 9. Poorly differentiated squamous cell carcinoma (SCC) had paramount higher expression with a median IRS of 6. Similar IRS and above (IRS, 6–9) was observed in Stage I (five cases), which recurred and well-differentiated cases with metastasis (four cases) while in leukoplakia with dysplasia the SALL4 expression was weak with a range of 2–4.

CONCLUSIONS:

SALL4 being one of the cancer stem cell molecules plays an important role in the progression of oral cancer, which was evident in this study. This could also account for aggressive clinical behavior. Follow-up of these patients would relate this molecule could be responsible for cancer relapse. Patients diagnosed to have oral epithelial dysplasia had a low expression of SALL4, are under follow-up, although seven cases did transform to SCC. Thus, we conclude, SALL4 may be of prognostic relevance, but in oral epithelial dysplasia, it requires further investigations.

Overexpression of Sal-like protein 4 in head and neck cancer: epigenetic effects and clinical correlations

BACKGROUND

Sal-like protein 4 (SALL4), an embryonic stem cell factor, has been reported to play an essential role in embryogenesis and oncogenesis. As yet, however, the expression and role of this transcription factor in head and neck squamous cell carcinoma (HNSCC) has not been established.

METHODS

We assessed SALL4 mRNA expression in a well-characterised dataset of 230 HNSCC samples (test cohort 110 cases and validation cohort 120 cases). We also transfected HNSCC cells (FaDu and UM-SCC-6) with SALL4 siRNA and assessed its effects on proliferation and expression of specific epigenetic factors in order to uncover the role of SALL4 in HNSCC.

RESULTS

Overexpression of SALL4 was detected in tumour samples of both cohorts. HNSCC cells treated with SALL4 siRNA showed a reduction in growth and a decrease in DNA methyltransferase 3 alpha (DNMT3A) expression. In the patient cohorts, SALL4 overexpression was found to significantly correlate with disease recurrence (p < 0.001) and SALL4 methylation status (p = 0.002). We also found that DNMT3A was significantly upregulated upon SALL4 upregulation (p < 0.001). High expression levels of SALL4 correlated with decreases in disease-free survival (DFS) rates (log-rank test, p < 0.001). Multivariate analysis revealed that SALL4 expression served as an independent prognostic factor for DFS (hazard ratio: 2.566, 95% confidence interval: 1.598-4.121; p < 0.001).

CONCLUSIONS

Our findings indicate that SALL4 upregulation correlates with HNSCC tumour aggressiveness and an adverse patient outcome. Our findings also indicate that DNMT3A may synergistically contribute to the regulatory effects of SALL4. Our findings provide insight into SALL4-mediated HNSCC development via epigenetic modulation.

Molecular Mechanisms by Which S100A4 Regulates the Migration and Invasion of PGCCs With Their Daughter Cells in Human Colorectal Cancer

Recently, an increasing number of evidences have shown that polyploid giant cancer cells (PGCCs) could generate daughter cells with a strong migration and invasion ability, which have been implicated in cancer recurrence and metastasis. However, the underlying molecular mechanisms of PGCCs with their daughter cells remain largely unclear. In vitro and in vivo experiments combined with 222 cases of human colorectal cancer (CRC) samples were used to identify the molecular mechanisms of S100A4-related proteins regulating the invasion and metastasis of PGCCs with their daughter cells. PGCCs with their daughter cells had high migration, invasion, and proliferation abilities compared to control cells; these were significantly inhibited after S100A4 knockdown. The high expression of cathepsin B, cyclin B1, TRIM21, and Annexin A2 were significantly downregulated after S100A4 knockdown, while the overexpression of S100A4, cathepsin B, cyclin B1, and S100A10 were significantly downregulated after TRIM21 knockdown in PGCCs with their daughter cells. The tumorigenic and metastatic ability of PGCCs with their daughter cells in vivo was significantly stronger compared to the untreated cells, which was significantly decreased after S100A4 knockdown. Moreover, the expression of S100A4-related proteins was positively correlated with the malignancy degree of human CRC, and maintained a high level in lymph node metastasis. S100A4 and TRIM21 may regulate each other to affect the expression and subcellular localization of cyclin B1, and participate in regulating the structure and function of Annexin A2/S100A10 complex, affecting downstream cathepsin B, resulting in the invasion and metastasis of PGCCs with their daughter cells. Besides, 14-3-3 ζ/δ and Ezrin may be involved in the motility and invasion of PGCCs with their daughter cells via cytoskeletal constructions with S100A4.

Decreased expression of TRIM21 indicates unfavorable outcome and promotes cell growth in breast cancer

Background

Tripartite motif-containing protein 21 (TRIM21), an E3 ubiquitin ligase, has been implicated in autoimmune diseases. Dysregulation of TRIM21 contributes to the progression of human malignancies, but its role and clinical significance in breast cancer remain unclear.

Methods

The expression of TRIM21 was examined by quantitative real-time PCR, Western blot, and immunohistochemistry. The role of TRIM21 in the progression of breast cancer was determined using in vitro and in vivo models. The upstream regulation of TRIM21 was investigated by luciferase reporter assay.

Results

Here, we showed that TRIM21 expression in breast cancer tissues was decreased at both the mRNA and protein levels in comparison to that in nontumorous tissues. TRIM21 expression was closely associated with tumor size, estrogen receptor, human epidermal growth factor receptor 2, and clinical stage. Low TRIM21 expression was correlated with poor overall and disease-free survival in two independent cohorts containing 1,219 patients with breast cancer. A multivariate Cox regression model suggested TRIM21 as an independent factor for overall survival. In vitro data revealed that TRIM21 expression was suppressed by miR-494-3p directly targeting the 3′ untranslated region of TRIM21. Overexpression of TRIM21 impeded cell proliferation and tumor growth in breast cancer, whereas TRIM21 depletion enhanced these capacities.

Conclusion

Collectively, our findings indicate that TRIM21 serves as a potential prognostic biomarker and functions as a tumor suppressor in breast cancer.