TRIM44 Promotes Rabies Virus Replication by Autophagy-Dependent Mechanism.

Tripartite motif (TRIM) proteins are a multifunctional E3 ubiquitin ligase family that participates in various cellular processes. Recent studies have shown that TRIM proteins play important roles in regulating host-virus interactions through specific pathways, but their involvement in response to rabies virus (RABV) infection remains poorly understood. Here, we identified that several TRIM proteins are upregulated in mouse neuroblastoma cells (NA) after infection with the rabies virus using RNA-seq sequencing. Among them, TRIM44 was found to regulate RABV replication. This is supported by the observations that downregulation of TRIM44 inhibits RABV replication, while overexpression of TRIM44 promotes RABV replication. Mechanistically, TRIM44-induced RABV replication is brought about by activating autophagy, as inhibition of autophagy with 3-MA attenuates TRIM44-induced RABV replication. Additionally, we found that inhibition of autophagy with rapamycin reverses the TRIM44-knockdown-induced decrease in LC3B expression and autophagosome formation as well as RABV replication. The results suggest that TRIM44 promotes RABV replication by an autophagy-dependent mechanism. Our work identifies TRIM44 as a key host factor for RABV replication, and targeting TRIM44 expression may represent an effective therapeutic strategy.

Silencing LINC00491 inhibits prostate cancer development through the miR-384/TRIM44 axis.

Accumulating evidence has demonstrated the key role of long noncoding (lnc)RNAs in tumorigenesis. Prostate cancer (PCa) is a cancer with high mortality that requires further exploration of the underlying molecular mechanisms. In the present study, we aimed to discover novel potential biomarkers for diagnosing PCa and targeting treatment. Overexpression of the lncRNA, LINC00491, was verified in PCa tumor tissues and cell lines using the real-time polymerase chain reaction. Cell proliferation and invasion were then analyzed via the Cell Counting Kit-8, colony formation, and transwell assays in vitro, and tumor growth in vivo. The interaction of miR-384 with LINC00491, as well as TRIM44, was investigated via bioinformatics analyses, subcellular fractionation, luciferase reporter gene assays, radioimmunoprecipitation, pull-down, and western blot analyses. LINC00491 was overexpressed in PCa tissues and cell lines. LINC00491 knockdown resulted in impaired cell proliferation and invasion in vitro and decreased tumor growth in vivo. Moreover, LINC00491 acted as a sponge for miR-384 and its downstream target, TRIM44. Additionally, miR-384 expression was downregulated in PCa tissues and cell lines, and its expression was negatively correlated with LINC00491. A miR-384 inhibitor restored the inhibitory effects of LINC00491 silencing on PCa cell proliferation and invasion. LINC00491 is a tumor promoter in PCa via enhancing TRIM44 expression by sponging miR-384 to facilitate the development of PCa. LINC00491 plays a significant role in PCa and could serve as both a biomarker for early diagnosis and a novel treatment target.

Silencing of TRIM44 Inhibits Inflammation and Alleviates Traumatic Brain Injury in Rats by Downregulating TLR4-NF-κB Signaling.

BACKGROUND: Neuroinflammation subsequent to traumatic brain injury (TBI) is important for the recovery of patients and is associated with neurodegenerative changes post-TBI. The tripartite motif containing 44 (TRIM44) protein is an E3 ligase involved in the regulation of immune function with no previously known link to TBI. This study explores the connection between TRIM44 and TBI. METHODS: After induction of TBI in rats by control cortex injury, TRIM44 expressions were determined with quantitative real-time reverse transcription polymerase chain reaction and Western blot, and Toll-like receptor 4 (TLR4)-NF-κB signaling was examined by the expression of TLR4, p65 phosphorylation, and the specific NF-κB transcription activity. The effects of TRIM44 knockdown on inflammation, neurological function, and TLR4-NF-κB signaling in TBI rats were revealed by the detection of proinflammatory cytokines and TLR4-NF-κB signaling molecules, modified neurological severity score, brain water content, and Evans blue permeability. RESULTS: We found that TRIM44 expression was significantly increased following TBI induction along with TLR4-NF-κB activation. Silencing of TRIM44 suppressed proinflammatory cytokine production, improved neurological outcomes, alleviated brain edema, and inhibited TLR4-NF-κB signaling in TBI rats. CONCLUSION: Our findings suggest that suppressing TRIM44 or modulation of relevant pathways may be a therapeutic strategy for TBI.

Knockdown of circRAD23B Exerts Antitumor Response in Colorectal Cancer via the Regulation of miR-1205/TRIM44 axis.

BACKGROUND: Colorectal cancer (CRC) is a common cancer with high metastatic property. Circular RNAs (circRNAs) have important involvement in cancer processes. This study focused on the regulation of circRNA RAD23 homologue B (circRAD23B) in CRC. METHODS: The levels of circRAD23B, microRNA-1205 (miR-1205), and tripartite motif-44 (TRIM44) were examined by quantitative real-time polymerase chain reaction (qRT-PCR). Functional analyses were performed by Cell Counting Kit-8 (CCK-8) for cell proliferation, flow cytometry for cell cycle or cell apoptosis, and transwell assay for cell migration and invasion. Western blot was administrated for protein detection. The interaction of targets was analyzed by dual-luciferase reporter and RNA pull-down assays. The in vivo experiment was conducted via xenograft tumor in mice. RESULTS: We identified that circRAD23B was overexpressed in CRC tissues and cells. CRC cell proliferation, cell cycle progression, and cell metastasis were inhibited, while apoptosis was promoted by downregulating circRAD23B. Target analysis indicated that circRAD23B-targeted miR-1205 and TRIM44 were downstream genes of miR-1205. Moreover, the antitumor response of circRAD23B downregulation and miR-1205 overexpression was, respectively, achieved by increasing miR-1205 and decreasing TRIM44. CircRAD23B could regulate TRIM44 level by sponging miR-1205. In vivo, circRAD23B knockdown also reduced CRC tumorigenesis via the miR-1205/TRIM44 axis. CONCLUSION: These results suggested that the inhibition of circRAD23B retarded the progression of CRC via acting on the miR-1205/TRIM44 axis. CircRAD23B might be a novel target in CRC treatment.

CircFBXW8 Acts an Oncogenic Role in the Malignant Progression of Non-small Cell Lung Carcinoma by miR-370-3p-Dependent Regulation of TRIM44.

Non-small cell lung carcinoma (NSCLC) is an aggressive malignant tumor. Growing evidences have revealed that circular RNA (circRNA) is involved in NSCLC progression. This study aims to investigate the role of circular RNA F-box and WD repeat domain containing 8 (circFBXW8) in NSCLC progression and the underlying mechanism. The expression of circFBXW8, microRNA-370-3p (miR-370-3p) and tripartite motif containing 44 (TRIM44) mRNA was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Protein expression was detected by western blot analysis or immunohistochemistry assay. Additionally, cell viability, colony-forming ability, proliferation and apoptosis were investigated by 3-(4,5-Dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide, cell colony formation, 5-Ethynyl-29-deoxyuridine and flow cytometry analysis assays, respectively. Cell migratory and invasive abilities were examined by wound-healing and transwell assays. The regulatory relationship between miR-370-3p and circFBXW8 or TRIM44 was identified by dual-luciferase reporter and RNA pull-down assays. Furthermore, xenograft experiment was employed to explain the effect of circFBXW8 silencing on tumor formation. CircFBXW8 and TRIM44 expression were upregulated, while miR-370-3p was downregulated in NSCLC tissues, cells and the exosomes from NSCLC cells compared with respective controls. CircFBXW8 depletion repressed NSCLC cell proliferation, migration and invasion, but promoted cell apoptosis. CircFBXW8 acted as a sponge of miR-370-3p and regulated NSCLC cell malignancy by binding to miR-370-3p. Additionally, miR-370-3p repressed NSCLC cell processes by regulating TRIM44. CircFBXW8 knockdown inhibited tumor formation in vivo. Further, circFBXW8 secretion was mediated by exosomes. CircFBXW8 modulated NSCLC progression by increasing TRIM44 expression through sponging miR-370-3p, which provided a new direction for studying the therapy of NSCLC.

Expression of tripartite motif-containing 44 and its prognostic and clinicopathological value in human malignancies:a meta-analysis.

BACKGROUND: Previous researches have reported that tripartite motif-containing 44 (TRIM44) is related to the prognosis of multiple human tumors. This study was designed to systematically assess the prognostic value of TRIM44 in human malignancies and summarize its possible tumor-related mechanisms. METHODS: The available databases were searched for eligible studies that evaluated the clinicopathological and prognostic roles of TRIM44 in patients with malignancies. The hazard ratios (HR) and odds ratios (OR) were combined to assess the predictive role of TRIM44 using Stata/SE 14.1 software. RESULTS: A total of 1740 patients from thirteen original studies were finally included in this study. The results of the combined analysis showed that over-expression of TRIM44 protein was significantly correlated with shorter overall survival (OS) (HR = 1.94, 95% CI: 1.60-2.35) and worse disease-free survival (DFS) (HR = 2.13, 95% CI: 1.24-3.65) in cancer patients. Additionally, the combined ORs indicated that elevated expression level of TRIM44 protein was significantly associated with lymph node metastasis (OR = 2.69, 95% CI: 1.71-4.24), distant metastasis (OR = 10.35, 95% CI: 1.01-106.24), poor tumor differentiation (OR = 1.78, 95% CI: 1.03-3.09), increased depth of tumor invasion (OR = 2.72, 95% CI: 1.73-4.30), advanced clinical stage (OR = 2.75, 95% CI: 2.04-3.71), and recurrence (OR = 2.30, 95% CI: 1.34-3.95). Furthermore, analysis results using Gene Expression Profiling Interactive Analysis (GEPIA) showed that the expression level of TRIM44 mRNA was higher in most tumor tissues than in the corresponding normal tissues, and the relationship between TRIM44 mRNA level and prognosis in various malignant tumors also explored in GEPIA and OS analysis webservers. CONCLUSIONS: TRIM44 may serve as a valuable prognostic biomarker and a potential therapeutic target for patients with malignancies.

Knockdown of HIF1A-AS2 suppresses TRIM44 to protect cardiomyocytes against hypoxia-induced injury.

Myocardial infarction (MI) is a common cardiovascular disease characterized by an interruption of blood and oxygen supply to the heart, which results in gradual damage to the myocardial tissue and ultimately heart failure. The role of long non-coding RNAs in the pathology of MI remains in its infancy, but has been implicated in MI and other heart conditions. For example, the expression of a non-coding RNA hypoxia-inducible factor 1α (HIF1A)-antisense RNA 2 (HIF1A-AS2) has previously been linked to coronary heart disease, however, whether HIF1A-AS2 expression is also high in MI has not been addressed. Here, we report that HIF1A-AS2 is upregulated in hypoxia-treated human cardiomyocytes (HMCs) compared with normal cardiomyocytes, and that silenced HIF1A-AS2 inhibited apoptosis and facilitated viability, migration, and invasion of HMCs. Our data suggested that in MI, HIF1A-AS2 upregulation was associated with miR-623, which promoted expression of tripartite motif containing 44 (TRIM44). Moreover, by upregulating TRIM44 we were able to remedy the HIF1A-AS2 repression of apoptosis in HMCs. Thus, we conclude that cardiomyocytes can be protected against hypoxic-treated injury by knockdown of HIF1A-AS2, which suppresses TRIM44, and that HIF1A-AS2 overexpression is a prognostic indicator of MI.

TRIM44 is indispensable for glioma cell proliferation and cell cycle progression through AKT/p21/p27 signaling pathway.

PURPOSE: Glioma is one of the lethal cancers which needs effective therapeutic target. TRIM44 has been found playing a carcinogenic role in human tumors such as breast cancer and ovarian cancer. However, the pathophysiological significance of TRIM44 in glioma is still unclear. METHODS: Quantitative-PCR and western blot were used to assess the expression of TRIM44 in glioma cells. For cell proliferation, Brdu incorporation and colony formation assays were performed. By Caspase 3 staining and FACS analysis, we revealed that TRIM44 knockdown induced glioma cell apoptosis. A BALB/c nude mouse xenograft model and following immunohistochemical (IHC) staining enables us to explore the effect of TRIM44 deletion on glioma growth in vivo. Western blot of p21, p27 and AKT indicated the possible role of TRIM44 in regulation AKT pathway in glioma. RESULTS: TRIM44 was significantly elevated in glioma cells, and high expression of TRIM44 is related to poor prognostic of glioma patients. TRIM44 knockdown by shRNAs inhibit glioma cell proliferation, migration, induced cell cycle disruption and further cellular apoptosis in vitro. As well, TRIM44 inactivation obviously inhibit tumor growth in xenograft model. Furthermore, the negative cell cycle regulators p21/p27 are significantly upregulated, while AKT which is known as the main regulator of p21/p27 is inactivated in TRIM44-dificient cells. These results suggested that TRIM44 inactivation disrupted cell cycle progression and inhibit cell proliferation through AKT/p21/p27 pathway in glioma. CONCLUSION: TRIM44 was associated with oncogenic potential of glioma. Targeting TRIM44 might be beneficial for glioma therapy.

MiR-101-3p inhibits EMT to attenuate proliferation and metastasis in glioblastoma by targeting TRIM44.

BACKGROUND: Glioblastoma (GBM) is the most common malignant tumor originating in the brain parenchyma. The invasive and infiltrative properties of glioblastoma result in poor clinical prognosis to conventional therapies. Emerging reports on microRNAs as important regulators during the process of EMT provide new insights into treating glioblastoma through new targets. However, underlying molecular mechanism of the regulation of miR-101-3p in glioblastoma remains unclear. METHODS: Level of miR-101-3p was determined in GBM cell lines by qRT-PCR. MTT, colony formation and transwell assays were utilized to evaluate functions of overexpression of miR-101-3p/knock down of TRIM44 on proliferation, migration and invasion in GBM cells. Direct interaction between miR-101-3p and TRIM44 was validated using dual luciferase reporter system and impacts of overexpression of miR-101-3p/knock down of TRIM44 on regulation of EMT markers were assessed by Western blotting. RESULTS: MiR-101-3p was validated to be repressed expressed in glioblastoma cancer cell lines. Both overexpression of miR-101-3p and knock down of TRIM44 attenuated proliferation, migration and invasion of glioblastoma cell lines in vitro. TRIM44 was shown to promote EMT in GBM progress and reverse inhibitory function of miR-101-3p. MiR-101-3p was found to suppress the expression of TRIM44 via directly targeting its 3'UTR. CONCLUSIONS: Our findings suggested miR-101-3p regulated proliferation and migration of glioblastoma cells through attenuating TRIM44 induced EMT via direct targeting 3'UTR of TRIM44, which provided preliminary study of potential therapeutic target in future GBM treatment.

TRIM44 promotes human esophageal cancer progression via the AKT/mTOR pathway.

Aberrant expression of TRIM-containing protein 44 (TRIM44) acts as a promoter in multiple cancers. Here, we investigated the biological functions and clinical significance of TRIM44 in human esophageal cancer (HEC). TRIM44 expression was significantly higher in HEC tissues than corresponding normal tissues at both the mRNA (2.42 ± 0.52 vs 0.99 ± 0.25) and protein (1.01 ± 0.27 vs 0.30 ± 0.13) levels. Patients with high TRIM44 expression showed poor differentiation (P = 1.39 × 10-5 ), advanced TNM stage (P = 3.87 × 10-4 ) and, most importantly, significantly poorer prognosis (P = 2.80 × 10-5 ). TRIM44 played a crucial role in epithelial mesenchymal transition (EMT). A significant correlation was observed between TRIM44 and Ki67 expression. We demonstrated that TRIM44 markedly enhanced HEC cell proliferation, migration, and invasion. Additionally, TRIM44 was involved in the AKT/mTOR signaling pathway and its downstream targets, such as STAT3 phosphorylation. Thus, elevated TRIM44 expression promotes HEC development by EMT via the AKT/mTOR pathway, and TRIM44 may be a novel prognostic indicator for HEC patients after curative resection.

Overexpression of TRIM44 is related to invasive potential and malignant outcomes in esophageal squamous cell carcinoma.

Recent studies have shown that some members of the tripartite motif-containing protein family function as important regulators for carcinogenesis. In this study, we investigated whether tripartite motif-containing protein 44 acts as a cancer-promoting gene through its overexpression in esophageal squamous cell carcinoma. We analyzed esophageal squamous cell carcinoma cell lines to evaluate malignant potential and also analyzed 68 primary tumors to evaluate clinical relevance of tripartite motif-containing protein 44 protein in esophageal squamous cell carcinoma patients. Expression of the tripartite motif-containing protein 44 protein was detected in esophageal squamous cell carcinoma cell lines (8/14 cell lines; 57%) and primary tumor samples of esophageal squamous cell carcinoma (39/68 cases; 57%). Knockdown of tripartite motif-containing protein 44 expression in esophageal squamous cell carcinoma cells using several specific small interfering RNAs inhibited cell migration and invasion, but not cell proliferation. Immunohistochemical analysis demonstrated that the overexpression of the tripartite motif-containing protein 44 protein in the tumor infiltrated region was associated with the status of lymph node metastasis ( p = 0.049), and the overall survival rates were significantly worse among patients with tripartite motif-containing protein 44-overexpressing tumors than those with non-expressing tumors ( p = 0.029). Moreover, multivariate Cox regression model identified that overexpression of the tripartite motif-containing protein 44 protein was an independent worse prognostic factor (hazard ratio = 2.815; p = 0.041), as well as lymphatic invasion (hazard ratio = 2.735; p = 0.037). These results suggest that tripartite motif-containing protein 44 protein could play a crucial role in tumor invasion through its overexpression and highlight its usefulness as a predictor and potential therapeutic target in esophageal squamous cell carcinoma.

TRIM44 Is a Poor Prognostic Factor for Breast Cancer Patients as a Modulator of NF-κB Signaling.

Many of the tripartite motif (TRIM) proteins function as E3 ubiquitin ligases and are assumed to be involved in various events, including oncogenesis. In regard to tripartite motif-containing 44 (TRIM44), which is an atypical TRIM family protein lacking the RING finger domain, its pathophysiological significance in breast cancer remains unknown. We performed an immunohistochemical study of TRIM44 protein in clinical breast cancer tissues from 129 patients. The pathophysiological role of TRIM44 in breast cancer was assessed by modulating TRIM44 expression in MCF-7 and MDA-MB-231 breast cancer cells. TRIM44 strong immunoreactivity was significantly associated with nuclear grade (p = 0.033), distant disease-free survival (p = 0.031) and overall survival (p = 0.027). Multivariate analysis revealed that the TRIM44 status was an independent prognostic factor for distant disease-free survival (p = 0.005) and overall survival (p = 0.002) of patients. siRNA-mediated TRIM44 knockdown significantly decreased the proliferation of MCF-7 and MDA-MB-231 cells and inhibited the migration of MDA-MB-231 cells. Microarray analysis and qRT-PCR showed that TRIM44 knockdown upregulated CDK19 and downregulated MMP1 in MDA-MB-231 cells. Notably, TRIM44 knockdown impaired nuclear factor-kappa B (NF-κB)-mediated transcriptional activity stimulated by tumor necrosis factor α (TNFα). Moreover, TRIM44 knockdown substantially attenuated the TNFα-dependent phosphorylation of the p65 subunit of NF-κB and IκBα in both MCF-7 and MDA-MB-231 cells. TRIM44 would play a role in the progression of breast cancer by promoting cell proliferation and migration, as well as by enhancing NF-κB signaling.

High expression of TRIM44 is associated with enhanced cell proliferation, migration, invasion, and resistance to doxorubicin in hepatocellular carcinoma.

Dysregulation of TRIM44 has been reported to be involved in tumorigenesis, but its role in hepatocellular carcinoma (HCC) remains unclear. In the present study, we investigated the clinicopathological and biological significance of TRIM44 in HCC. We found that TRIM44 mRNA and protein expression was upregulated in HCC compared with matched normal tissues. Intriguingly, we also found that TRIM44 expression was significantly correlated with tumor size (P < 0.001), vascular invasion (P < 0.001), intrahepatic metastasis (P < 0.001), distant metastasis (P < 0.001), and Ki-67 expression (P < 0.001). Kaplan-Meier analysis showed that high TRIM44 staining was significantly correlated with shorter overall survival (P < 0.001). TRIM44 was an independent predictor of overall survival in patients with HCC. Furthermore, we found that ectopic expression of TRIM44 could promote cell proliferation via accelerating the G1/S-phase transition in HCC. Moreover, overexpression of TRIM44 could enhance the invasive and migratory capacity of HCC cells. Meanwhile, we found that high expression of TRIM44 could enhance resistance of HCC cells to doxorubicin via accelerating NF-κB activation. In conclusion, our results suggest that TRIM44 may be a novel prognostic indicator and potential therapeutic target of HCC.

Variants in TRIM44 Cause Aniridia by Impairing PAX6 Expression.

Congenital aniridia is a genetic disorder that manifests as iris hypoplasia and other associated ocular complications. Mutations in the paired box 6 (PAX6) gene are considered the major cause of aniridia. In this study, we identified four mutations exclusively presented in aniridia patients from a four-generation Chinese pedigree, including two single nucleotide substitutions in the 3'UTR of PAX6 (NM_000280.4:c.[*76G>A; *2977C>A]) and two missense mutations in tripartite motif containing 44 (TRIM44, NM_017583.4:c.[191C>A; 463G>A]), which lead to amino acid changes p.S64Y and p.G155R, respectively. Bioinformatic analyses revealed that the two 3'UTR mutations of PAX6 disrupted microRNA binding motifs in the wildtype 3'UTR sequence. Luciferase reporter assay and Western blotting with predicted microRNAs showed that the two 3'UTR mutations could only increase or have no effect on the expression of PAX6. Therefore, they would not be the cause of aniridia that resulted from PAX6 deficiency. Instead, we found that overexpression of TRIM44 significantly reduced the expression of PAX6 in human lens epithelial cells, and the p.G155R mutant exhibited much stronger effect than the wildtype form. We conclude that inhibition of PAX6 expression by mutant TRIM44 is a novel pathogenic mechanism for aniridia.

Overexpression of TRIM44 mediates the NF-κB pathway to promote the progression of ovarian cancer.

BACKGROUND: Ovarian cancer (OC) is the second most commonly seen cancer in the US, and patients with OC are commonly diagnosed in the advanced stage. Research into the molecular mechanisms and potential therapeutic targets of OC is becoming increasingly urgent. In our study, we worked to discover the role of TRIM44 in OC development. OBJECTIVE: This study explored whether the overexpression of TRIM44 mediates the NF-kB pathway to promote the progression of OC. METHODS: A TRIM44 overexpression model was constructed in SKOV3 cells, and the proliferation ability of the cells was detected using the CCK-8 assay. The migration healing ability of cells was detected using cell scratch assay. Cell migration and invasion were detected using Transwell nesting. TUNEL was applied to detect apoptosis, and ELISA and western blot were used to detect the expression of NF-κB signaling pathway proteins. The pathological changes of the tumor tissues were observed using HE staining in a mouse ovarian cancer xenograft model. Immunofluorescence double staining, RT-PCR, and western blot were used to determine the expression of relevant factors in tumour tissues. RESULTS: TRIM44 overexpression promoted the proliferation, migration, and invasion of SKOV3 cells in vitro and inhibited apoptosis while enhancing the growth of tumours in vivo. TRIM44 regulated the NF-κB signaling pathway. CONCLUSIONS: TRIM44 overexpression can regulate the NF-κB signaling pathway to promote the progression of OC, and TRIM44 may be a potential therapeutic target for OC.

TRIM44 regulates tumor immunity in gastric cancer through LOXL2-dependent extracellular matrix remodeling.

PURPOSE: Gastric cancer is a gastrointestinal malignancy with high mortality and poor prognosis, and the molecular mechanism of gastric tumorigenesis remains unclear. TRIM44 has been reported to be involved in tumor development. However, the role of TRIM44 in tumor immunity is largely unknown. METHODS: We analyzed TRIM44 expression in clinical gastric cancer tissues and normal tissues by using western blot, quantitative real-time PCR and bioinformatics analyses. We further investigated the involvement of TRIM44 in tumor immunity in vivo and found that it was dependent on extracellular matrix remodeling. We detected the interaction between TRIM44 and LOXL2 by using immunofluorescence staining and coimmunoprecipitation assays. We observed that TRIM44 mediates the stability of LOXL2 by ubiquitination assays. RESULTS: TRIM44 expression is high and is correlated with T-cell infiltration in gastric cancer. TRIM44 inhibits gastric tumorigenicity by regulating T-cell-mediated antitumor immunity and modulating the protein level of LOXL2. Mechanistically, TRIM44 directly binds to LOXL2 and affects the stability of LOXL2 to change extracellular matrix remodeling and influence tumor immunity. CONCLUSION: These findings demonstrate that TRIM44 regulates the stability of LOXL2 to remodel the tumor extracellular matrix to modulate tumor immunity in gastric cancer and that the TRIM44/LOXL2 complex is a promising biomarker for gastric cancer prognosis and might be a novel immunotherapy target.

Cardiac-specific Trim44 knockout in rat attenuates isoproterenol-induced cardiac remodeling via inhibition of AKT/mTOR pathway.

When pathological hypertrophy progresses to heart failure (HF), the prognosis is often very poor. Therefore, it is crucial to find new and effective intervention targets. Here, myocardium-specific Trim44 knockout rats were generated using CRISPR-Cas9 technology. Cardiac phenotypic observations revealed that Trim44 knockout affected cardiac morphology at baseline. Rats with Trim44 deficiency exhibited resistance to cardiac pathological changes in response to stimulation via isoproterenol (ISO) treatment, including improvement of cardiac remodeling and dysfunction by morphological and functional observations, reduced myocardial fibrosis and reduced expression of molecular markers of cardiac stress. Furthermore, signal transduction validation associated with growth and hypertrophy development in vivo and in vitro demonstrated that Trim44 deficiency inhibited the activation of signaling pathways involved in myocardial hypertrophy, especially response to pathological stress. In conclusion, the present study indicates that Trim44 knockout attenuates ISO-induced pathological cardiac remodeling through blocking the AKT/mTOR/GSK3ß/P70S6K signaling pathway. This is the first study to demonstrate the function and importance of Trim44 in the heart at baseline and under pathological stress. Trim44 could be a novel therapeutic target for prevention of cardiac hypertrophy and HF.

TRIM-containing 44 aggravates cardiac hypertrophy via TLR4/NOX4-induced ferroptosis.

TRIM-containing 44 (TRIM44) is a promoter of multiple cancers. However, its role in cardiac hypertrophy has not been elucidated. This study explored the role of TRIM44 on pressure overload-induced cardiac hypertrophy in mice. Mice were subjected to aortic banding to establish an adverse cardiac hypertrophy model, followed by the administration of AAV9-TRIM44 or AAV9shTRIM44 to overexpress or knock down TRIM44. Echocardiography was used to assess cardiac function. H9c2 cells were cultured and transfected with either Ad-TRIM44 or TRIM44 siRNA to overexpress or silence TRIM44. Cells were also stimulated with angiotensin II to establish a cardiomyocyte hypertrophy model. Results indicated that TRIM44 was downregulated in mice hearts and cardiomyocytes that were treated with aortic banding or angiotensin II. TRIM44 overexpression in mice hearts aggravated cardiac hypertrophy and fibrosis, as well as inhibited cardiac function post-aortic banding. Moreover, mice with TRIM44 overexpression displayed increased ferroptosis post-aortic banding. Mice with TRIM44 knockdown revealed ameliorated cardiac hypertrophy, ferroptosis, and fibrosis, as well as improved cardiac function post-aortic banding. In H9c2 cells transfected with Ad-TRIM44, angiotensin II-induced ferroptosis was enhanced, while cells with silenced TRIM44 reported reduced ferroptosis post-angiotensin II administration. Furthermore, TRIM44 interacted with TLR4, which increased the expression of NOX4 and subsequently augmented ferroptosis-associated protein levels. By using TLR4 knockout mice, the inhibitory role of TRIM44 was reduced post-aortic banding. Taken together, TRIM44 aggravated pressure overload-induced cardiac hypertrophy via increased TLR4/NOX4-associated ferroptosis. KEY MESSAGES: TRIM44 could aggregate pressure overload-induced cardiac hypertrophy via increasing TLR4-NOX4 associated ferroptosis. Target TRIM44 may become a new therapeutic method for preventing or treating pressure overload-induced cardiac hypertrophy.

TRIM44 aggravates cardiac fibrosis after myocardial infarction via TAK1 stabilization.

Myocardial infarction (MI) is one of the most dangerous cardiovascular events. Cardiac fibrosis is a common pathological feature of remodeling after injury that is related to adverse clinical results with no effective treatment. Previous studies have confirmed that TRIM44, an E3 ligase, can promote the proliferation and migration of various tumor cells. However, the role of TRIM44 in cardiac fibrosis remains unknown. Models of TGF-ß1 stimulation and MI-induced fibrosis were established to investigate the role and potential underlying mechanism of TRIM44 in cardiac fibrosis. The results showed that cardiac fibrosis was significantly inhibited after TRIM44 knockdown in a mouse model of MI, while it was enhanced when TRIM44 was overexpressed. Furthermore, in vitro studies showed that fibrosis markers were significantly reduced in cardiac fibroblasts (CFs) with TRIM44 knockdown, whereas TRIM44 overexpression promoted the expression of fibrosis markers. Mechanistically, TRIM44 maintains TAK1 stability by inhibiting the degradation of k48-linked polyubiquitination-mediated ubiquitination, thereby increasing phosphorylated TAK1 expression in the fibrotic environment and activating MAPKs to promote fibrosis. Pharmacological inhibition of TAK1 phosphorylation reversed the fibrogenic effects of TRIM44 overexpression. Combined, these results suggest that TRIM44 is a potential therapeutic target for cardiac fibrosis.

TRIM44 promotes BRCA1 functions in HR repair to induce Cisplatin Chemoresistance in Lung Adenocarcinoma by Deubiquitinating FLNA.

Tripartite motif-containing 44 (TRIM44) has recently been implicated in various pathological processes in numerous cancers, including lung adenocarcinoma (LUAD); however, its functional roles in chemoresistance are poorly understood. Herein, TRIM44 knockdown sensitized LUAD cells to cisplatin and enhanced cisplatin-induced apoptosis. Microarray analysis indicated that the "Role of BRCA1 in DNA damage" and the BRCA1 gene expression were positively regulated by TRIM44, which was further verified by immunofluorescence, qRT-PCR, and Western blotting. BRCA1 depletion effectively abolished TRIM44-modulated cisplatin resistance and regulation of homologous recombination (HR) repair. Interestingly, TRIM44 interacted with FLNA, an upstream regulator of BRCA1 as specified by STRING V 11.5, and facilitated its stability and deubiquitination. FLNA was also found to be required for the functions of TRIM44 in drug resistance. Using animal models, overexpression of TRIM44 was shown to confer resistance to cisplatin in a BRCA1- and FLNA-dependent manner. TRIM44 expression levels in tissues from cisplatin-resistant LUAD patients were significantly higher than those in tissues from cisplatin-sensitive LUAD patients. Collectively, our study results demonstrate that the TRIM44/FLNA/BRCA1 axis is involved in cisplatin chemoresistance, providing potential therapeutic targets for LUAD patients with cisplatin resistance.