HECTD2/TNFAIP1 Axis Regulating the p38/JNK Pathway to Promote an Inflammatory Response in Renal Cell Carcinoma Cells

BACKGROUND/AIM

The underlying processes of renal cell carcinoma (RCC), one of the deadliest malignancies of the urinary system, are still poorly understood. HECT domain E3 ubiquitin protein ligase 2 (HECTD2) is an E3 ubiquitin ligase implicated in the pulmonary inflammatory response. This study investigated the impact of HECTD2 on regulating inflammation in RCC cells and its potential mechanisms.

MATERIALS AND METHODS

HECTD2 expression in RCC tissues was examined. Immunoprecipitation and western blot (WB) analysis confirmed that HECTD2 up-regulated euchromatic histone lysine methyltransferase 2 (EHMT2) protein degradation. ChIP experiments validated tumor necrosis factor α Inducing protein 1 (TNFAIP1) as a direct target of EHMT2. qRT-PCR determined HECTD2 and TNFAIP1 expression in RCC cells. Cell viability was assayed via CCK-8. ELISA was employed to measure the expression of IL-6, TNF-α, IL-8, and IL-1β. WB analysis was conducted to test p38/JNK pathway-related protein (p38, p-p38, JNK, and p-JNK) expression.

RESULTS

HECTD2 and TNFAIP1 were significantly up-regulated in RCC patient tissues and cells. Subsequent investigations revealed that HECTD2 promoted an inflammatory response in RCC cells. Additionally, HECTD2 up-regulated TNFAIP1 expression, and high TNFAIP1 expression could reverse the repressive impact of low HECTD2 expression on the inflammatory response in RCC cells. Rescue experiments demonstrated that the addition of p38/JNK pathway inhibitors attenuated the impact of TNFAIP1 overexpression on the RCC inflammatory response.

CONCLUSION

Our findings establish a new mechanism by which HECTD2 exerts a pro-inflammatory role in RCC cells and present a prospective method for an anti-inflammatory intervention targeting the HECTD2/TNFAIP1 axis in malignancies.

Neuronal-specific TNFAIP1 ablation attenuates postoperative cognitive dysfunction via targeting SNAP25 for K48-linked ubiquitination

BACKGROUND

Synaptosomal-associated protein 25 (SNAP25) exerts protective effects against postoperative cognitive dysfunction (POCD) by promoting PTEN-induced kinase 1 (PINK1)/Parkin-mediated mitophagy and repressing caspase-3/gasdermin E (GSDME)-mediated pyroptosis. However, the regulatory mechanisms of SNAP25 protein remain unclear.

METHODS

We employed recombinant adeno-associated virus 9 (AAV9)-hSyn to knockdown tumor necrosis factor α-induced protein 1 (TNFAIP1) or SNAP25 and investigate the role of TNFAIP1 in POCD. Cognitive performance, hippocampal injury, mitophagy, and pyroptosis were assessed. Co-immunoprecipitation (co-IP) and ubiquitination assays were conducted to elucidate the mechanisms by which TNFAIP1 stabilizes SNAP25.

RESULTS

Our results demonstrated that the ubiquitin ligase TNFAIP1 was upregulated in the hippocampus of mice following isoflurane (Iso) anesthesia and laparotomy. The N-terminal region (residues 1-96) of TNFAIP1 formed a conjugate with SNAP25, leading to lysine (K) 48-linked polyubiquitination of SNAP25 at K69. Silencing TNFAIP1 enhanced SH-SY5Y cell viability and conferred antioxidant, pro-mitophagy, and anti-pyroptosis properties in response to Iso and lipopolysaccharide (LPS) challenges. Conversely, TNFAIP1 overexpression reduced HT22 cell viability, increased reactive oxygen species (ROS) accumulation, impaired PINK1/Parkin-dependent mitophagy, and induced caspase-3/GSDME-dependent pyroptosis by suppressing SNAP25 expression. Neuron-specific knockdown of TNFAIP1 ameliorated POCD, restored mitophagy, and reduced pyroptosis, which was reversed by SNAP25 depletion.

CONCLUSIONS

In summary, our findings demonstrated that inhibiting TNFAIP1-mediated degradation of SNAP25 might be a promising therapeutic approach for mitigating postoperative cognitive decline. Video Abstract.

Knocking down TNFAIP1 alleviates inflammation and oxidative stress in pediatric pneumonia through PI3K/Akt/Nrf2 pathway

BACKGROUND

Pneumonia is an acute respiratory infection with increasing global incidences. Children are more susceptible to pneumonia than adults, and its incidences grow extremely high during peak seasons. Thus, it is necessary to investigate the pathogenesis and molecular mechanism of childhood pneumonia.

METHODS

This study examined the role of tumor necrosis factor alpha-inducible protein 1 (TNFAIP1) in lipopolysaccharide (LPS)-induced pneumonia mice. After LPS exposure, lung function, TNFAIP1 activation, infarction volume, oxidative stress, lung tissue apoptosis ratio, and inflammatory response were assessed by immunohistochemistry staining, hematoxylin and eosin staning, Western blot analysis, terminal deoxynucleotidyl transferase dUTP nick end labelling assay, and enzyme-linked-immunosorbent serologic assay, respectively. The mechanism of TNFAIP1 regulating phosphoinositide 3-kinases (PI3K)-protein kinase B (Akt)-nuclear factor erythroid 2-related factor 2 (Nrf2) pathway was analyzed by Western blot analysis.

RESULTS

TNFAIP1 expression was enhanced in the LPS-induced pneumonia mice but was negatively correlated with the LPS-induced lung injury. Silencing TNFAIP1 alleviated inflammatory response, production of reactive oxygen species (ROS), and cellular apoptosis in LPS-induced pneumonia. Moreover, PI3K/Akt/Nrf2 signaling pathways were predominantly involved in the TNFAIP1-mediated lung injury, which also played a role in the process of LPS-induced pneumonia.

CONCLUSION

This study suggested that TNFAIP1 acted as a negative regulator of acute pneumonia by attenuating inflammatory response, production of ROS, and cellular apoptosis via PI3K/Akt/Nrf2 pathway. The findings suggested that TNFAIP1 is a potential candidate for pneumonia therapy.

LncRNA NKILA Exacerbates Alzheimer's Disease Progression by Regulating the FOXA1-Mediated Transcription of TNFAIP1

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases in the world, which seriously affects AD patients' life quality. Recently, long non-coding RNAs (lncRNAs) have been reported to play a key role in AD pathogenesis, however, the specific mechanism remains unclear. Herein, we aimed to investigate the role of lncRNA NKILA in AD. The learning and memory performance of rats from streptozotocin (STZ)-treated or other treated groups were tested by Morris water maze test. Relative levels of genes and proteins were measured using RT-qPCR and Western blotting. Mitochondrial membrane potential was tested by JC-1 staining. Levels of ROS, SOD, MDA, GSH-Px, and LDH were measured using corresponding commercial kits. Apoptosis was evaluated by TUNEL staining or Flow cytometry assay. RNA Immunoprecipitation (RIP), RNA pulldown, Chromatin immunoprecipitation (ChIP), and dual-luciferase reporter assays were utilized to test the interaction between indicated molecules. STZ treatment caused learning and memory impairment in rats and oxidative stress damage in SH-SY5Y cells. LncRNA NKILA was found to be elevated in the hippocampal tissues of rats and SH-SY5Y cells after STZ exposure. Knockdown of lncRNA NKILA alleviated STZ-induced neuronal damage. Furthermore, lncRNA NKILA could bind to ELAVL1, which regulate the stability of FOXA1 mRNA. Moreover, TNFAIP1 transcription process was controlled by FOXA1, which targeted the promoter of TNFAIP1. In vivo results demonstrated that lncRNA NKILA accelerated STZ-induced neuronal damage and oxidative stress by FOXA1/TNFAIP1 axis. Our findings indicated that knockdown of lncRNA NKILA inhibited the neuronal damage and oxidative stress induced by STZ through the FOXA1/TNFAIP1 axis, thereby alleviating the development of AD, revealing a promising therapeutic axis for AD treatment.

Epigenetic axis of SNHG19/miR-137/TNFAIP1 modulates amyloid beta peptide 25-35-induced SH-SY5Y cytotoxicity

Aims: In this study, the authors hypothesized that, in an in vitro Alzheimer's disease model, the epigenetic axis of SNHG19/hsa-miR-137 functionally regulates amyloid beta peptide 25-35 (Aβ_25-35)-induced SH-SY5Y cytotoxicity. Methods: Dual luciferase activity assay demonstrated that SNHG19 could directly bind hsa-miR-137. In Aβ_25-35-treated SH-SY5Y cells, SNHG19 was upregulated and hsa-miR-137 downregulated. Results: SNHG19 knockdown ameliorated Aβ_25-35-induced SH-SY5Y cytotoxicity, then reversed by secondary hsa-miR-137 downregulation. TNFAIP1 was dynamically regulated by Aβ_25-35 and gene modifications in SH-SY5Y cells. Finally, upregulation of TNFAIP1 reversed the protective effect of SNHG19 knockdown on Aβ_25-35-induced cytotoxicity. Conclusions: The authors concluded that the epigenetic axis of SNHG19/hsa-miR-137/TNFAIP1 may functionally regulate Aβ_25-35-induced SH-SY5Y cytotoxicity, thus making it a potential molecular target for Alzheimer's disease treatment.

The role of TNF-α induced protein 1 in the activation of pro-apoptotic proteins

It is known that Porphyromonas gingivalis/lipopolysaccharide (P. gingivalis/LPS) induces inflammatory diseases via TNF-α-mediated transcription factors. Our recent data shows that TNFAIP1 (TNF-α induced protein 1) is related to TNF-α. However, little is known regarding how TNFAIP1 is involved in the TNF-α-dependent pathway. We therefore focused on the biological function of TNFAIP1 and examined how TNFAIP1 mediates TNF-α and other genes. We found that TNF-α was upregulated and peaks before the upregulation of apoptotic genes such as Bad, Bcl-x, Caspase 3, Catalase, Claspin, Cytochromic, Ho-1/HMOX1/HSP32, or MCI-1 in our time course with TNFAIP1-treated cells. Our findings here may serve as the foundation for future studies linking regulation of TNFAIP1 and intervention of inflammatory disease.

Cullin3-TNFAIP1 E3 Ligase Controls Inflammatory Response in Hepatocellular Carcinoma Cells via Ubiquitination of RhoB

Rho family GTPase RhoB is the critical signaling component controlling the inflammatory response elicited by pro-inflammatory cytokines. However, the underlying mechanisms of RhoB degradation in inflammatory response remain unclear. In this study, for the first time, we identified that TNFAIP1, an adaptor protein of Cullin3 E3 ubiquitin ligases, coordinated with Cullin3 to mediate RhoB degradation through ubiquitin proteasome system. In addition, we demonstrated that downregulation of TNFAIP1 induced the expression of pro-inflammatory cytokines IL-6 and IL-8 in TNFα-stimulated hepatocellular carcinoma cells through the activation of p38/JNK MAPK pathway via blocking RhoB degradation. Our findings revealed a novel mechanism of RhoB degradation and provided a potential strategy for anti-inflammatory intervention of tumors by targeting TNFAIP1-RhoB axis.

TNFAIP1 Is Upregulated in APP/PS1 Mice and Promotes Apoptosis in SH-SY5Y Cells by Binding to RhoB

Alzheimer's disease (AD) poses a significant threat to human life and health. The intraneuronal accumulation of β-amyloid (Aβ) plaques in the brains of AD patients results in neuronal cell death, which is a key factor that triggers multiple changes in the pathogenesis of AD. The inhibition of Aβ-induced neuronal cell death may potentially help in the intervention and treatment of AD. Our previous study reported that tumor necrosis factor α-induced protein 1 (TNFAIP1) is induced by and promotes Aβ_25-35-induced neurotoxicity in mouse neuronal cells, but the roles and regulatory mechanisms of TNFAIP1 are still largely unknown. In this study, our experimental results show that TNFAIP1 and p-TNFAIP1 (phosphorylation of TNFAIP1 at Ser280) are overexpressed in the neurons of the cortex and hippocampus in the brains of APP/PS1 mice, and the transcription factor NF-κB is involved in the Aβ-induced upregulation of TNFAIP1. Moreover, our results suggest that TNFAIP1 contributes to the Aβ-induced reactive oxygen species (ROS) production, decreased mitochondrial membrane potential (∆Ψm), and neuronal cell death in human SH-SY5Y cells. We further revealed that Aβ increases the binding of TNFAIP1 to RhoB, and knockdown of RhoB attenuates the TNFAIP1-induced apoptosis of human SH-SY5Y cells. These data suggest that TNFAIP1 is closely associated with AD pathogenesis, and overexpression of TNFAIP1 in the neurons of the brains of AD patients plays a role in apoptosis, at least in part, via RhoB signaling.

Circ0001320 inhibits lung cancer cell growth and invasion by regulating TNFAIP1 and TPM1 expression through sponging miR-558

Lung cancer is the most affected malignant tumor in the world, and its specific pathogenesis is still unclear. It has been confirmed that circ0001320 is down-regulated in lung cancer, but its mechanism has not been reported. Further study found that circ0001320 was down-regulated in lung cancer cells, localized in the cytoplasm, and had multiple miR-558 binding sites. Dual-luciferase reporter gene assay, RNA-pull-down, and immunoprecipitation experiments all confirmed that circ0001320 directly bound to miR-558, and then inhibit the expression of miR-558. MiR-558 was up-regulated in lung cancer cells, and bound the downstream target genes TNFAIP1 and TPM1 to inhibit their expression. Western blot showed that circ0001320 significantly up-regulated the protein levels of TNFAIP1 and TPM1, while miR-558 blocked this effect of circ0001320. Circ0001320, TNFAIP1, and TPM1 all inhibited the proliferation and invasion of lung cancer cells and promoted apoptosis, while miR-558 had the opposite effects. After transfection with circ0001320 overexpression vector, miR-558 up-regulation or down-regulation of TNFAIP1, or TPM1 expression significantly reversed the inhibition of cell growth and invasion by circ0001320. Similarly, the expression of TNFAIP1 or TPM1 was down-regulated, while miR-558 expression was inhibited, and the levels of cell proliferation, apoptosis, and invasion did not change significantly. Therefore, these fully show that circ0001320 inhibits the growth and invasion of lung cancer cells through miR-558/TNFAIP1 and TPM1 pathways, which may be closely related markers and therapeutic targets of lung cancer.

miR-29c-3p Increases Cell Viability and Suppresses Apoptosis by Regulating the TNFAIP1/NF-κB Signaling Pathway via TNFAIP1 in Aβ-Treated Neuroblastoma Cells

Alzheimer's disease (AD) is the most common cause of dementia among older people in worldwide. miR-29c-3p was reported to play a role in AD development. However, the detail function of miR-29c-3p in AD remains unclear. The aim of this research is to analyze the functional mechanism of miR-29c-3p in AD. The RNA levels of miR-29c-3p and Tumor necrosis factor-α-inducible protein-1 (TNFAIP1) were detected by Quantitative real time polymerase chain (qRT-PCR) reaction. Western blot assay was carried out to examine the protein levels of TNFAIP1, Bax, B-cell lymphoma-2 (Bcl-2), Cleaved caspase 3, and Nuclear factor-k-gene binding (NF-κB). The interaction between miR-29c-3p and TNFAIP1 was predicted by online tool TargrtScan and verified using the dual luciferase reporter assay and RNA immunoprecipitation RIP (RIP) assay. Besides, cell proliferation and apoptosis rate were determined by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay and flow cytometry analysis, respectively. Aβ treatment decreased miR-29c-3p expression and increased TNFAIP1 expression. Overexpression of miR-29c-3p mitigated the effects of Aβ on proliferation and apoptosis. Similarly, knockdown of TNFAIP1 also reversed the effects of Aβ on cell progression. Interestingly, miR-29c-3p suppressed the expression of TNFAIP1 via binding to 3'UTR of TNFAIP1 mRNA. As expected, overexpression of TNFAIP1 reversed the effects of miR-29c-3p on Aβ-mediated cell progression. Besides, we also confirmed that miR-29c-3p affected Aβ-mediated cell progression by regulating TNFAIP1/NF-κB signaling pathway. In conclusion, our findings confirmed that miR-29c-3p attenuated Aβ-induced neurotoxicity through regulation of NF-κB signaling pathway by directly targeting TNFAIP1, providing the potential value for the treatment of AD patients.

TNFAIP1 Mediates Formaldehyde-Induced Neurotoxicity by Inhibiting the Akt/CREB Pathway in N2a Cells

Formaldehyde (FA) is a common air pollutant. Exposure to exogenous FA can cause damage to the nervous system, such as learning and memory impairment, balance dysfunction, and sleep disorders. Excessive production of endogenous FA also causes memory impairment and is thought to be associated with Alzheimer's disease (AD). Tumor necrosis factor alpha-induced protein 1 (TNFAIP1) plays a crucial role in neurodevelopment and neurological diseases. However, the role of TNFAIP1 in FA-induced neurotoxicity is unclear. Herein, using a mouse neuroblastoma cell line (N2a cells), we explored the mechanism of TNFAIP1 in FA-induced neurotoxicity, the involvement of the Akt/CREB signaling pathway, and how the expression of TNFAIP1 is regulated by FA. We found that exposure to 100 μM or 200 μM FA for 24 h led to decreased cell viability, increased cell apoptosis and neurite retraction, increased reactive oxygen species (ROS) levels, upregulated protein expression of TNFAIP1 and decreased the levels of phosphorylated Akt and CREB in the Akt/CREB pathway. Knockdown of TNFAIP1 using a TNFAIP1 small interfering RNA (siRNA) expression vector prevented FA from inhibiting the Akt/CREB pathway, thus reducing cell apoptosis and restoring cell viability and neurite outgrowth. Clearance of ROS by vitamin E (Vit E) repressed the FA-mediated upregulation of TNFAIP1 expression. These results suggest that FA increases the expression of TNFAIP1 by inducing oxidative stress and that upregulated TNFAIP1 then inhibits the Akt/CREB pathway, consequently leading to cell apoptosis and neurite retraction. Therefore, TNFAIP1 is a potential target for alleviating FA-induced neurotoxicity and related neurological disorders.

Knockdown of TNFAIP1 prevents di-(2-ethylhexyl) phthalate-induced neurotoxicity by activating CREB pathway

Di-(2-ethylhexyl) phthalate (DEHP) is a widely used plasticizer. It has neurotoxicity and exposure to it causes impairment of neurodevelopment, behavior and cognition. However, the molecular mechanisms responsible for the DEHP-induced neurotoxicity are not yet clearly defined. Tumor necrosis factor-induced protein 1 (TNFAIP1) was first discovered in umbilical vein endothelial cells and was further found to be important in the progress of Alzheimer's disease. Herein we explore the mechanism of TNFAIP1 in DEHP-induced neurotoxicity with the involvement of cyclic AMP response elements binding protein (CREB) signaling pathway in a mouse neuroblastoma cell line (N2a cells). We found that exposure to DEHP induced apoptosis and downregulated the expression of brain-derived neurotrophic factor (BDNF), synaptic proteins PSD 95 and synapsin-1 while upregulated the expression of TNFAIP1 and decreased the levels of phosphorylated Akt, CaMK Ⅳ, catalytic subunits of PKA and CREB in CREB signaling pathway. Knockdown of TNFAIP1 using TNFAIP1 small interfering RNA (siRNA) expression vector prevented DEHP from inhibiting CREB pathway, thus reduced apoptosis and restored expression of BDNF, PSD 95 and synapsin-1. Our data indicate that downregulation of TNFAIP1 prevents DEHP-induced neurotoxicity via activating CREB pathway. Therefore, TNFAIP1 is a potential target for relieving the DEHP-induced neurotoxicity and related neurological disorders.

Effects of XIST/miR-137 axis on neuropathic pain by targeting TNFAIP1 in a rat model

Non-coding RNAs have been reported to participate in the pathophysiology of neuropathic pain. The objective of our study was to investigate the biological role of XIST in neuropathic pain development. In our study, we identify and validate that lncRNA XIST was markedly increased and miR-137 was significantly decreased in chronic constriction injury (CCI) rats. XIST silencing alleviated pain behaviors including both mechanical and thermal hyperalgesia in the CCI rats. XIST was predicted to interact with miR-137 by bioinformatics technology and dual-luciferase reporter assays confirmed the correlation between XIST and miR-137. miR-137 was negatively modulated by XIST and upregulation of miR-137 greatly reduced neuropathic pain development in CCI rats. Moreover, we observed that tumor necrosis factor alpha-induced protein 1 (TNFAIP1) was enhanced in CCI rats and 3'-untranslated region (UTR) of TNFAIP1 was exhibited to be a target of miR-137 by bioinformatics prediction. TNFAIP1 can act as a crucial inflammation regulator by activating NF-kB activity. Overexpression of miR-137 significantly suppressed TNFAIP1 both in vitro and in vivo. Furthermore, upregulation of XIST reversed the inhibitory role of miR-137 in neuropathic pain development by inhibiting TNFAIP1. In conclusion, our current study indicates that XIST can positively regulate neuropathic pain in rats through regulating the expression of miR-137 and TNFAIP1. Our results imply that XIST/miR-137/TNFAIP1 axis may serve as a novel therapeutic target in neuropathic pain.

miR-137 attenuates Aβ-induced neurotoxicity through inactivation of NF-κB pathway by targeting TNFAIP1 in Neuro2a cells

BACKGROUND

Accumulation of β-amyloid (Aβ) and neuroinflammation are implicated in the pathogenesis and development of Alzheimer's disease (AD). Neuron-enriched miR-137 was aberrantly downregulated and may be associated with the pathogenesis of AD. However, the detailed function of miR-137 in AD pathogenesis and the molecular mechanism have not been elucidated.

METHODS

The expressions of miR-137 and tumor necrosis factor alpha (TNFα)-induced protein 1 (TNFAIP1) at mRNA and protein levels in primary mouse cortical neurons and Neuro2a (N2a) cells exposed to different concentrations of Aβ_25-35 were examined by qRT-PCR and western blot. Luciferase reporter assay was used to confirm the potential target of miR-137. MTT assay, flow cytometry analysis, caspase-3 activity assay, Enzyme-linked immunosorbent assay (ELISA), and western blot were used to detect cell viability, apoptosis, caspase-3 activity, Nuclear factor-kappa B (NF-κB) activity and level, respectively.

RESULTS

Aβ_25-35 downregulated miR-137 and upregulated TNFAIP1 in primary mouse cortical neurons and N2a cells. In addition, miR-137 was found to directly target TNFAIP1 and suppress its mRNA and protein levels. Moreover, miR-137 restoration and TNFAIP1 knockdown facilitate Aβ_25-35-induced cell toxicity, apoptosis, caspase-3 activity, and activated NF-κB in N2a cells, which was partially abolished by TNFAIP1 overexpression.

CONCLUSION

miR-137 attenuated Aβ-induced neurotoxicity through inactivation of NF-κB pathway by targeting TNFAIP1 in N2a cells, shedding light on the molecular mechanism of miR-137 underlying Aβ-induced neurotoxicity.

MiR-424 Promotes Non-Small Cell Lung Cancer Progression and Metastasis through Regulating the Tumor Suppressor Gene TNFAIP1

BACKGROUND/AIMS

This study aimed to investigate the potential roles of miR-424 expression in non-small cell lung cancer (NSCLC) metastasis and growth and its underlying mechanism.

METHODS

The expression of miR-424 in two NSCLC cell lines (A549 and H1975) was altered by transfection with miR-424 mimic and inhibitor. Effects of miR-424 overexpression and suppression on cells migration, invasion and colony formation were analyzed. Target genes for miR-424 were predicted using bioinformatics method and then verified using luciferase assay. Effects of miR-424 expression on cell migration, invasion and proliferation were reanalyzed on the condition of TNFAIP1 was silenced. Moreover, TNFAIP1 silencing and miR-424 modified A549 cells were subcutaneous injected into node BALB/c mice to confirm the regulation of miR-424 on TNFAIP1 in regulating tumor growth.

RESULTS

Compared with the control, miR-424 overexpression significantly increased the migrated and invaded cells, as well as the proliferated colonies. TNFAIP1 was a predicted target gene for miR-424, and was negatively regulated by miR-424. TNFAIP1 silence significantly increased the migrated and invaded cells compared to that in control, while these increases were abolished by miR-424 suppression. Animal experiment further evidenced miR-424 affected tumor growth by regulating TNFAIP1.

CONCLUSIONS

These data demonstrate that miR-424 may be a contributor for NSCLC progression and metastasis through involving in cell migration, invasion and proliferation via inhibiting TNFAIP1. This study may provide theoretical basis for miR-424 in NSCLC target therapeutic treatment.

TNFAIP1 contributes to the neurotoxicity induced by Aβ25-35 in Neuro2a cells

BACKGROUND

Amyloid-beta (Aβ) accumulation is a hallmark of Alzheimer's disease (AD) that can lead to neuronal dysfunction and apoptosis. Tumor necrosis factor, alpha-induced protein 1 (TNFAIP1) is an apoptotic protein that was robustly induced in the transgenic C. elegans AD brains. However, the roles of TNFAIP1 in AD have not been investigated.

RESULTS

We found TNFAIP1 protein and mRNA levels were dramatically elevated in primary mouse cortical neurons and Neuro2a (N2a) cells exposed to Aβ25-35. Knockdown and overexpression of TNFAIP1 significantly attenuated and exacerbated Aβ25-35-induced neurotoxicity in N2a cells, respectively. Further studies showed that TNFAIP1 knockdown significantly blocked Aβ25-35-induced cleaved caspase 3, whereas TNFAIP1 overexpression enhanced Aβ25-35-induced cleaved caspase 3, suggesting that TNFAIP1 plays an important role in Aβ25-35-induced neuronal apoptosis. Moreover, we observed that TNFAIP1 was capable of inhibiting the levels of phosphorylated Akt and CREB, and also anti-apoptotic protein Bcl-2. TNFAIP1 overexpression enhanced the inhibitory effect of Aβ25-35 on the levels of p-CREB and Bcl-2, while TNFAIP1 knockdown reversed Aβ25-35-induced attenuation in the levels of p-CREB and Bcl-2.

CONCLUSION

These results suggested that TNFAIP1 contributes to Aβ25-35-induced neurotoxicity by attenuating Akt/CREB signaling pathway, and Bcl-2 expression.

MicroRNA-224 promotes tumor progression in nonsmall cell lung cancer. Proc Natl Acad Sci U S A. 2015;112:E4288-E4297. [PMID: 26187928 DOI: 10.1073/pnas.1502068112]

Lung cancer is the leading cause of cancer-related deaths worldwide. Despite advancements and improvements in surgical and medical treatments, the survival rate of lung cancer patients remains frustratingly poor. Local control for early-stage nonsmall cell lung cancer (NSCLC) has dramatically improved over the last decades for both operable and inoperable patients. However, the molecular mechanisms of NSCLC invasion leading to regional and distant disease spread remain poorly understood. Here, we identify microRNA-224 (miR-224) to be significantly up-regulated in NSCLC tissues, particularly in resected NSCLC metastasis. Increased miR-224 expression promotes cell migration, invasion, and proliferation by directly targeting the tumor suppressors TNFα-induced protein 1 (TNFAIP1) and SMAD4. In concordance with in vitro studies, mouse xenograft studies validated that miR-224 functions as a potent oncogenic miRNA in NSCLC in vivo. Moreover, we found promoter hypomethylation and activated ERK signaling to be involved in the regulation of miR-224 expression in NSCLC. Up-regulated miR-224, thus, facilitates tumor progression by shifting the equilibrium of the partially antagonist functions of SMAD4 and TNFAIP1 toward enhanced invasion and growth in NSCLC. Our findings indicate that targeting miR-224 could be effective in the treatment of certain lung cancer patients.

Interaction between microRNA-181a and TNFAIP1 regulates pancreatic cancer proliferation and migration

We investigated the role of microRNA 181a (miR-181a) and its downstream target tumor necrosis factor, alpha-induced protein 1 (TNFAIP1) in pancreatic cancer regulation. Quantitative real-time PCR (qRT-PCR) was applied to evaluate the gene expression of miR-181a in seven pancreatic cancer cell lines. MiR-181a inhibitor lentivirus (miR-181a-IN) was used to down-regulate miR-181a in Capan-1 and AsPC-1 cells. The effects of miR-181a down-regulation on pancreatic cancer were evaluated by in vitro proliferation assay and migration assay. Targeting of miR-181a on TNFAIP1 in pancreatic cancer was evaluated by dual-luciferase reporter assay and western blot. TNFAIP1 was either upregulated by pcDNA3.1 (+) expression vector or down-regulated by siRNA in Capan-1 and AsPC-1 cells. The subsequent effects of TNFAIP1 upregulation or down-regulation on miR-181a mediated pancreatic cancer regulation were also evaluated through in vitro proliferation and migration assays. The in vivo effect of miR-181a down-regulation on pancreatic tumor growth was evaluated by a xenograft assay. MiR-181a was consistently upregulated in pancreatic cancer cell lines. MiR-181a down-regulation inhibited proliferation and migration in vitro, and upregulated TNFAIP1 in pancreatic cancer cells. Ectopic TNFAIP1 overexpression had similar tumor-suppressive effects on pancreatic cancer proliferation and migration as miR-181a down-regulation, whereas siRNA-mediated TNFAIP1 down-regulation had opposite or oncogenic effects on pancreatic cancer. In vivo pancreatic xenograft showed miR-181a recapitulated the in vitro anti-tumor effects and its regulation on TNFAIP1. MiR-181a played a critical role in regulating pancreatic cancer growth and migration, likely interacting with TNFAIP1.