A Novel 3-Benzyloxychromone From Celastrus orbiculatus Thunb. Exhibits Anticancer Effects on Non-Small Cell Lung Cancer Cells via GSK-3ß-Dependent c-Jun/ATF2 Pathway.

Celastrus orbiculatus Thunb. is a vine used as a traditional Chinese medicinal herb. In this study, we focused on the anticancer cytotoxicity and underlying mechanism of previously unreported 3-oxygen-substituted isoflavone analogue (3-benzyloxychromone, 3-Boc) from the herb. Initially, we established cell line-derived xenograft mouse model using H1299 non-small cell lung cancer (NSCLC) cells and found that the ethanol crude extracts of the stem part of C. orbiculatus (200 mg/kg) could substantially suppress the growth of xenograft tumors in athymic nu/nu mice. We compared 3-Boc with three other flavonoid analogues isolated from the stem part of C. orbiculatus. Among these, 3-Boc showed the most potent cytotoxicity against H1299 and H1975 NSCLC cells. Colony formation, EdU incorporation and Annexin V-FITC/PI apoptosis assays demonstrated that 3-Boc induced growth inhibition primarily by inhibiting DNA replication and inducing apoptotic death of NSCLC cells. Structure-based target prediction and MD simulation suggested that 3-Boc potentially suppressed the activity of glycogen synthase kinase-3ß (GSK-3ß) by interacting with the ATP-binding site. Western blot analysis indicated that 3-Boc triggered the phosphorylation of Serine 21 of GSK-3α or Serine 9 of GSK-3ß in a time- and dose-dependent manner. To investigate the dependency of GSK-3ß, we established GSK-3ß knockout in H1299 cells. Depletion of GSK-3ß enhanced 3-Boc-induced cytotoxicity compared with wild-type counterparts through activated c-Jun/ATF2 signaling pathway. Altogether, our study highlights the anticancer potential of C. orbiculatus and the discovery of novel 3-oxygen-substituted chromone from the herb, which may have important implications for screening promising modulators of GSK-3ß and related signaling pathways in the treatment of cancer.

Anti-psoriasis effect of 18ß-glycyrrhetinic acid by breaking CCL20/CCR6 axis through its vital active group targeting GUSB/ATF2 signaling.

BACKGROUND: Psoriasis is an immune-mediated chronic inflammatory skin disease. Current research suggests that the long-term persistence and recurrence of psoriasis are closely related to the feedback loop formed between keratinocytes and immune cells, especially in Th 17 or DC cells expressing CCR6. CCL20 is the ligand of CCR6. Therefore, drugs that block the expression of CCL20 or CCR6 may have a certain therapeutic effect on psoriasis. Glycyrrhetinic acid (GA) is the main active ingredient of the plant drug licorice and is often used to treat autoimmune diseases, including psoriasis. However, its mechanism of action is still unclear. METHODS: Psoriasis like skin lesion model was established by continuously applying imiquimod on the back skin of normal mice and CCR6-/- mice for 7 days. The therapeutic and preventive effects of glycyrrhetinic acid (GA) on the model were observed and compared. The severity of skin injury is estimated through clinical PASI scores and histopathological examination. qRT-PCR and multiple cytoline assay were explored to detect the expression levels of cytokines in animal dorsal skin lesions and keratinocyte line HaCaT cells, respectively. The dermis and epidermis of the mouse back were separated for the detection of CCL20 expression. Transcription factor assay was applied to screen, and luciferase activity assay to validate transcription factors regulated by GA. Technology of surface plasmon laser resonance with LC-MS (SPR-MS), molecular docking, and enzyme activity assay were used to identified the target proteins for GA. Finally, we synthesized different derivatives of 18beta-GA and compared their effects, as well as glycyrrhetinic acid (GL), on the skin lesion of imiquimod-induced mice to evaluate the active groups of 18beta-GA. RESULTS: 18ß-glycyrrhetinic acid (GA) improved IMQ-induced psoriatic lesions, and could specifically reduce the chemokine CCL20 level of the epidermis in lesion area, especially in therapeutic administration manner. The process was mainly regulated by transcription factor ATF2 in the keratinocytes. In addition, GUSB was identified as the primary target of 18ßGA. Our findings indicated that the subject on molecular target research of glycyrrhizin should be glycyrrhetinic acid (GA) instead of glycyrrhizic acid (GL), because GL showed little activity in vitro or in vivo. Apart from that, α, ß, -unsaturated carbonyl in C11/12 positions was crucial or unchangeable to its activity of 18ßGA, while proper modification of C3 or C30 position of 18ßGA may vastly increase its activity. CONCLUSION: Our research indicates that 18ßGA exerted its anti-psoriasis effect mainly by suppressing ATF2 and downstream molecule CCL20 predominately through α, ß, -unsaturated carbonyl at C11/12 position binding to GUSB in the keratinocytes, and then broke the feedback loop between keratinocytes and CCR6-expressing immune cells. GA has more advantages than GL in the external treatment of psoriasis. A highlight of this study is to investigate the influence of special active groups on the pharmacological action of a natural product, inspired by the molecular docking result.

The P38MAPK/ATF2 signaling pathway is involved in PND in mice.

Accumulating evidence indicates that microglia-mediated neuroinflammation in the hippocampus contributes to the development of perioperative neurocognitive disorder (PND). P38MAPK, a point of convergence for different signaling processes involved in inflammation, can be activated by various stresses. This study aims to investigate the role of the P38MAPK/ATF2 signaling pathway in the development of PND in mice. Aged C57BL/6 mice were subjected to tibial fracture surgery under isoflurane anesthesia to establish a PND animal model. The open field test was used to evaluate the locomotor activity of the mice. Neurocognitive function was assessed with the Morris water maze (MWM) and fear conditioning test (FCT) on postoperative days 1, 3 and 7. The mice exhibited cognitive impairment accompanied by increased expression of proinflammatory factors (IL-1ß, TNF-α), proapoptotic molecules (caspase-3, bax) and microglial activation in the hippocampus 1, 3 and 7 days after surgery. Treatment with SB239063 (a P38MAPK inhibitor) decreased the expression of proinflammatory factors, proapoptotic molecules and Iba-1 in the CA1 region of the hippocampus. The number of surviving neurons was significantly increased. Inhibition of the P38MAPK/ATF2 signaling pathway attenuates hippocampal neuroinflammation and neuronal apoptosis in aged mice with PND, thus improving the perioperative cognitive function of the mice.

Emerging roles of activating transcription factor 2 in the development of breast cancer: a comprehensive review.

Activating transcription factor 2 (ATF2) is a member of the leucine zipper family of DNA binding proteins that are responsible for regulating various genes that play an essential role in major biological and cellular functions. Since ATF2 plays a vital role in cellular proliferation and apoptosis, it is believed that it greatly affects the development of breast cancers. However, its exact role in breast cancer is incompletely understood. It remains a subject of debate, ambiguity, and continuous research. Several studies have suggested the role of ATF2 as an oncogene, promoting cellular proliferation and worsening the outcome of cancers. In contrast, other studies have postulated that ATF2 plays a tumor suppressive role in estrogen receptor-positive breast cancer. The ambiguity surrounding its role in breast cancer is the reason why there is an influx of recent studies and research in this area. In this narrative review, we investigate several studies that have been published about the role of ATF2 in breast cancer. We also explore studies that have examined the association between ATF2 and endocrine therapy resistance. ATF2 has been suggested to modulate estrogen receptor (ER) expression and activity, potentially affecting tamoxifen sensitivity in breast cancer cells. Therefore, the role of ATF2 in DNA repair mechanisms and drug resistance has been deeply explored in this review. Additionally, there are numerous ongoing clinical trials exploring the effect of targeting ATF2 pathways and mechanisms on the outcome of breast cancers, some of which we have discussed. The studies and clinical trials that are being conducted to understand the multifaceted role of ATF2 and its signaling pathways may provide valuable insight for developing efficient targeted therapeutic solutions to enhance the outcomes of breast cancer and overcome endocrine resistance. We suggest further research to elucidate the dual roles of ATF2 in breast cancer and potential therapeutic therapies for its treatment.

ANKRD49 promotes the metastasis of NSCLC via activating JNK-ATF2/c-Jun-MMP-2/9 axis.

BACKGROUND: Ankyrin repeat domain 49 (ANKRD49) has been found to be highly expressed in multiple cancer including lung adenocarcinoma (LUAD) and lung squamous carcinoma (LUSC). However, the function of ANKRD49 in the pathogenesis of NSCLC still remains elusive. Previously, ANKRD49 has been demonstrated to promote the invasion and metastasis of A549 cells, a LUAD cell line, via activating the p38-ATF-2-MMP2/MMP9 pathways. Considering the heterogeneity of tumor cells, the function and mechanism of ANKRD49 in NSCLC need more NSCLC-originated cells to clarify. METHODS: Real-time qPCR was employed to test ANKRD49 expression levels in nine pairs of fresh NSCLC tissues and the corresponding adjacent normal tissues. The function of ANKRD49 was investigated using overexpression and RNA interference assays in lung adenocarcinoma cell line (NCI-H1299) and lung squamous carcinoma cell line (NCI-H1703) through gelatin zymography, cell counting kit-8, colony formation, wound healing, migration and invasion assays mmunoprecipitation was performed to in vitro. Immunoprecipitation was performed to test the interaction of c-Jun and ATF2. Chromatin immunoprecipitation was conducted to assess the transcriptional regulation of ATF2/c-Jun on MMP-2/9. Moreover, the tumorigenicity of ANKRD49 was evaluated in nude mice models and the involved signal molecular was also measured by immunohistochemical method. RESULTS: We found that the levels of ANKRD49 in cancerous tissues were higher than those in adjacent normal tissues. in vitro assay showed that ANKRD49 promoted the migration and invasion of NCI-H1299 and NCI-H1703 cells via enhancing the levels of MMP-2 and MMP-9. Furthermore, ANKRD49 elevated phosphorylation of JNK and then activated c-Jun and ATF2 which interact in nucleus to promote the binding of ATF2:c-Jun with the promoter MMP-2 or MMP-9. In vivo assay showed that ANKRD49 promoted lung metastasis of injected-NSCLC cells and the high metastatic rate was positively correlated with the high expression of ANKRD49, MMP-2, MMP-9, p-JNK, p-c-Jun and p-ATF2. CONCLUSION: The present study indicated that ANKRD49 accelerated the invasion and metastasis of NSCLC cells via JNK-mediated transcription activation of c-Jun and ATF2 which regulated the expression of MMP-2/MMP-9. The molecular mechanisms of ANKRD49's function is different from those found in A549 cells. The current study is a supplement and improvement to the previous research.

ATF2-driven osteogenic activity of enoxaparin sodium-loaded polymethylmethacrylate bone cement in femoral defect regeneration.

BACKGROUND: Polymethylmethacrylate (PMMA) bone cement loaded with enoxaparin sodium (PMMA@ES) has been increasingly highlighted to affect the bone repair of bone defects, but the molecular mechanisms remain unclear. We addressed this issue by identifying possible molecular mechanisms of PMMA@ES involved in femoral defect regeneration based on bioinformatics analysis and network pharmacology analysis. METHODS: The upregulated genes affecting the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) were selected through bioinformatics analysis, followed by intersection with the genes of ES-induced differentiation of BMSCs identified by network pharmacology analysis. PMMA@ES was constructed. Rat primary BMSCs were isolated and cultured in vitro in the proliferation medium (PM) and osteogenic medium (OM) to measure alkaline phosphatase (ALP) activity, mineralization of the extracellular matrix, and the expression of RUNX2 and OCN using gain- or loss-of-function experiments. A rat femoral bone defect model was constructed to detect the new bone formation in rats. RESULTS: ATF2 may be a key gene in differentiating BMSCs into osteoblasts. In vitro cell assays showed that PMMA@ES promoted the osteogenic differentiation of BMSCs by increasing ALP activity, extracellular matrix mineralization, and RUNX2 and OCN expression in PM and OM. In addition, ATF2 activated the transcription of miR-335-5p to target ERK1/2 and downregulate the expression of ERK1/2. PMMA@ES induced femoral defect regeneration and the repair of femoral defects in rats by regulating the ATF2/miR-335-5p/ERK1/2 axis. CONCLUSION: The evidence provided by our study highlighted the ATF2-mediated mechanism of PMMA@ES in the facilitation of the osteogenic differentiation of BMSCs and femoral defect regeneration.

Sinapic acid alleviates inflammatory bowel disease (IBD) through localization of tight junction proteins by direct binding to TAK1 and improves intestinal microbiota.

Introduction: Although sinapic acid is found in various edible plants and has been shown to have anti-inflammatory properties including colitis, its underlying mechanism and effects on the composition of the gut microbiota are largely unknown. We aimed to identify an early response kinase that regulates the localization of tight junction proteins, act at the onset of the inflammatory response, and is regulated by sinapic acid. Additionally, we analyzed the effects of sinapic acid on the homeostasis of the intestinal microbiome. Methods: We examined the aberrant alterations of early response genes such as nuclear factor-kappa B (NF-κB) and activating transcription factor (ATF)-2 within 2 h of sinapic acid treatment in fully differentiated Caco-2 cells with or without lipopolysaccharide and tumor necrosis factor (TNF)-α stimulation. To confirm the effect of sinapic acid on stimulus-induced delocalization of tight junction proteins, including zonula occludens (ZO)-1, occludin, and claudin-2, all tight junction proteins were investigated by analyzing a fraction of membrane and cytosol proteins extracted from Caco-2 cells and mice intestines. Colitis was induced in C57BL/6 mice using 2% dextran sulfate sodium and sinapic acid (2 or 10 mg/kg/day) was administrated for 15 days. Furthermore, the nutraceutical and pharmaceutical activities of sinapic acid for treating inflammatory bowel disease (IBD) evaluated. Results: We confirmed that sinapic acid significantly suppressed the stimulus-induced delocalization of tight junction proteins from the intestinal cell membrane and abnormal intestinal permeability as well as the expression of inflammatory cytokines such as interleukin (IL)-1ß and TNF-α in vitro and in vivo. Sinapic acid was found to bind directly to transforming growth factor beta-activated kinase 1 (TAK1) and inhibit the stimulus-induced activation of NF-κB as well as MAPK/ATF-2 pathways, which in turn regulated the expression of mitogen-activated protein kinase (MLCK). Dietary sinapic acid also alleviated the imbalanced of gut microbiota and symptoms of IBD, evidenced by improvements in the length and morphology of the intestine in mice with colitis. Discussion: These findings indicate that sinapic acid may be an effective nutraceutical and pharmaceutical agent for IBD treatment as it targets TAK1 and inhibits subsequent NF-κB and ATF-2 signaling.

The transcription factor ATF2 promotes gastric cancer progression by activating the METTL3/cyclin D1 pathway.

Globally, gastric cancer (GC) is a major cause of cancer death. This study is aimed at investigating the biological functions of activating transcription factor 2 (ATF2) and the underlying mechanism in GC. In the present work, GEPIA, UALCAN, Human Protein Atlas and StarBase databases were adopted to analyze ATF2 expression characteristics in GC tissues and normal gastric tissues, and its relationships with tumor grade and patients' survival time. Quantitative real-time polymerase chain reaction (qRT-PCR) method was employed to examine ATF2 mRNA expression in normal gastric tissues, GC tissues, and GC cell lines. Cell counting kit-8 (CCK-8) and EdU assays were utilized for detecting GC cell proliferation. Cell apoptosis was detected by flow cytometry. PROMO database was applied to predict the binding site of ATF2 with the METTL3 promoter region. The binding relationship between ATF2 and the METTL3 promoter region was verified through dual-luciferase reporter gene assay and chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) assay. Western blot was performed to evaluate the effect of ATF2 on METTL3 expression. METTL3-related signaling pathways were predicted using Gene Set Enrichment Analysis (GSEA) in the LinkedOmics database. It was found that, ATF2 level was elevated in GC tissues and cell lines in comparison with normal tissues and correlated with short patients' survival time. ATF2 overexpression facilitated GC cell growth and suppressed the apoptosis, whereas ATF2 knockdown suppressed GC cell proliferation and facilitated the apoptosis. ATF2 bound to the METTL3 promoter region, and ATF2 overexpression promoted the transcription of METTL3, and ATF2 knockdown restrained the transcription of METTL3. METTL3 was associated with cell cycle progression, and ATF2 overexpression enhanced cyclin D1 expression, and METTL3 knockdown reduced cyclin D1 expression. In summary, ATF2 facilitates GC cell proliferation and suppresses the apoptosis via activating the METTL3/cyclin D1 signaling pathway, and ATF2 is promising to be an anti-drug target for GC.

ATF2 orchestrates macrophage differentiation and activation to promote antibacterial responses.

The differentiation and activation of macrophages are critical regulatory programs that are central to host inflammation and pathogen defense. However, the transcriptional regulatory pathways involved in these programs are not well understood. Herein, we demonstrate that the activity and expression of the transcription factor ATF2 is precisely regulated during primary human monocyte-to-macrophage differentiation and that its activation is linked to M1 polarization and antibacterial responses. Genetic perturbation experiments demonstrated that deletion of ATF2 (THP-ΔATF2) resulted in irregular and abnormal macrophage morphology, whereas macrophages overexpressing ATF2 (THP-ATF2) developed round and pancake-like morphology, resembling classically activated (M1) macrophages. Mechanistically, we show that ATF2 binds to the core promoter of PPM1A, a phosphatase that regulates monocyte-to-macrophage differentiation, to regulate its expression. Functionally, overexpression of ATF2 sensitized macrophages to M1 polarization, resulting in increased production of major histocompatibility complex class II, IL-1ß, and IP-10; improved phagocytic capacity; and enhanced control of the intracellular pathogen Mycobacterium tuberculosis. Gene expression profiling revealed that overexpression of ATF2 reprogramed macrophages to promote antibacterial pathways enriched in chemokine signaling, metabolism, and antigen presentation. Consistent with pathways analysis, metabolic profiling revealed that genetic overexpression or stimuli-induced activation of ATF2 alters the metabolic capacity of macrophages and primes these cells for glycolytic metabolism during M1 polarization or bacterial infection. Our findings reveal that ATF2 plays a central role during macrophage differentiation and M1 polarization to enhance the functional capacities of macrophages.

Amentoflavone attenuates cell proliferation and induces ferroptosis in human gastric cancer by miR-496/ATF2 axis.

Amentoflavone (AF) is a natural multifunctional biflavonoid that has been revealed to possess multiple biological activities, including anticancer activity. Here, this work focused on exploring the functions and mechanism of AF in gastric cancer (GC). Levels of genes and proteins were examined by quantitative real-time PCR and western blotting. Cell proliferation and cell death were analyzed using cell counting kit-8, colony formation, and lactate dehydrogenase (LDH) release assay, respectively. Cell ferroptosis was evaluated by detecting the levels of malondialdehyde (MDA), reduced glutathione (GSH), Fe2+ , and intracellular reactive oxygen species (ROS). The binding between miR-496 and activating transcription factor 2 (ATF2) was confirmed by using dual-luciferase reporter assay. Murine xenograft assay was conducted for in vivo experiments. The results showed that AF suppressed the proliferation and induced ferroptotic cell death in GC cells. MiR-496 expression was decreased in GC tissues and cells, and AF treatment increased miR-496 expression level in GC cells. Functionally, miR-496 inhibition reversed the inhibitory effects of AF on GC cell proliferation and promoting effects on ferroptotic cell death. Mechanistically, ATF2 was targeted by miR-496. ATF2 expression was increased in GC tissues and cells, which was decreased by AF treatment and subsequently rescued by miR-496 downregulation in GC cells. Moreover, miR-496 overexpression suppressed the proliferation and induced ferroptotic cell death in GC cells via targeting ATF2. In all, AF suppressed the proliferation and induced ferroptotic cell death in GC cells via miR-496/ATF2 axis, indicating a novel therapeutic approach for GC patients.

USP14 Regulates ATF2/PIK3CD Axis to Promote Microvascular Endothelial Cell Proliferation, Migration, and Angiogenesis in Diabetic Retinopathy.

Diabetic retinopathy (DR) is one of the leading causes of blindness in diabetic patients. However, the pathogenesis of DR is complex, and no firm conclusions have been drawn so far. It has become a hot spot in ophthalmology research to deeply study the mechanism of DR pathological changes and find effective treatment options. Human retinal microvascular endothelial cells (HRMECs) were induced by high glucose (HG) to construct DR cell model. CCK-8 assay was used to detect the viability of HRMECs. Transwell assay was used to detect the migration ability of HRMECs. Tube formation assay was used to identify the tube formation ability of HRMECs. The expressions of USP14, ATF2 and PIK3CD were detected by Western blot analysis and qRT-PCR assay. Immunoprecipitation (IP) was used to ascertain the relationship of USP14 and ATF2. To explore the regulatory relationship between ATF2 and PIK3CD by dual-luciferase reporter gene assay and Chromatin immunoprecipitation (ChIP) assay. High glucose treatment promoted the proliferation, migration, and tube formation of HRMEC, and the expressions of USP14, ATF2 and PIK3CD were significantly up-regulated. USP14 or ATF2 knockdown inhibited HG-induced HRMECs proliferation, migration, and tube formation. USP14 regulated the expression of ATF2, and ATF2 promoted PIK3CD expression. PIK3CD overexpression attenuated the inhibitory effectiveness of USP14 knockdown on proliferation, migration and tube formation of DR cell model. Here, we revealed that USP14 regulated the ATF2/PIK3CD axis to promote proliferation, migration, and tube formation in HG-induced HRMECs.

NEDD4L represses prostate cancer cell proliferation via modulating PHF8 through the ubiquitin–proteasome pathway

Purpose Prostate cancer (PC) is a heterogeneous malignancy that greatly threatens man’s health. E3 ubiquitin-protein ligase neural precursor cell expressed developmentally downregulated 4-like (NEDD4L) imparts an regulatory role in various malignancies. This study focused on the modulatory mechanism of NEDD4L in proliferation of prostate cancer cells (PCCs) via regulating histone demethylase plant homeodomain finger protein 8 (PHF8/KDM7B) through the ubiquitin–proteasome system. Methods The expression levels of NEDD4L, PHF8, H3 lysine 9 dimethylation (H3K9me2) and activating transcription factor 2 (ATF2) in PC tissues and cell lines were detected via real-time quantitative polymerase chain reaction and Western blotting. After transfection of pcDNA3.1-NEDD4L, pcDNA3.1-PHF8, and pcDNA3.1-ATF2 into PCCs, cell proliferation was assessed via the cell counting kit-8 and 5-ethynyl-2'-deoxyuridine assays. Interaction between NEDD4L and PHF8 was identified via the protein immunoprecipitation. The ubiquitination level of PHF8 was determined via the ubiquitination detection. The enrichments of H3K9me2 and PHF8 in the ATF2 promotor region were detected via the chromatin-immunoprecipitation assay. Results PHF8 and ATF2 were highly expressed while NEDD4L was poorly expressed in PC tissues and cells. NEDD4L overexpression reduced proliferation of PCCs. NEDD4L induced degradation of PHF8 via ubiquitination. PHF8 limited the enrichment of H3K9me2 in the ATF2 promotor region and enhanced ATF2 transcription. Up regulation of PHF8 or ATF2 abolished the inhibitory role of NEDD4L in proliferation of PCCs. Conclusion NEDD4L facilitated degradation of PHF8 to limit ATF2 transcription, thereby suppressing proliferation of PCCs. (AU)

Effects of the interaction between Brahma-related gene 1 and activating transcription factor 2 on the proliferation, migration and invasion of cutaneous squamous cell carcinoma cells / 中华皮肤科杂志

Objective:To determine the expression of Brahma-related gene 1 (BRG1) in cutaneous squamous cell carcinoma (cSCC) tissues and cells, and to investigate molecular mechanisms underlying the regulatory effect of its interaction with activating transcription factor 2 (ATF2) on the proliferation, migration and invasion of cSCC cells.Methods:From 2015 to 2021, 66 paraffin-embedded actinic keratosis (AK) tissue samples and 80 paraffin-embedded cSCC (including squamous cell carcinoma in situ) tissue samples were collected from the Department of Dermatology, Affiliated Hospital 2 of Nantong University, and the diagnoses of all the cases were confirmed histopathologically; at the same time, 35 paraffin-embedded normal skin tissue samples obtained by cosmetic surgery served as normal control group. Immunohistochemical staining was performed to determine the BRG1 expression in cSCC, AK, and normal skin tissues, and correlations between BRG1 expression and clinicopathological parameters of cSCC patients were analyzed. Fresh tissue samples were collected from 12 cSCC patients and 12 healthy controls, and cSCC cell lines A431 and Scl-1 and a human immortalized keratinocyte cell line HaCaT were routinely cultured; real-time fluorescence-based quantitative PCR (qRT-PCR) was performed to determine the mRNA expression of BRG1 in tissues and cells, and co-immunoprecipitation assay and cellular immunofluorescence staining were conducted to analyze the interaction between BRG1 and ATF2. The expression of BRG1 (BRG1 siRNA1 - 5 groups) and ATF2 (ATF2-shRNA group) in A431 and Scl-1 cells was knocked down by RNA interference, and cells transfected with negative control siRNA or shNC served as controls (control siRNA group and shNC group, respectively), cell counting kit-8 (CCK8) assay, colony formation assay, cell scratch assay, and Transwell assay were conducted to evaluate effects of knocking down BRG1 and ATF2 on the proliferation, migration, and invasion of cSCC cells. Comparisons of measurement data among multiple groups were conducted using one-way analysis of variance, and multiple comparisons were conducted using Dunnett- t test. Results:Immunohistochemical staining showed that the expression intensity of BRG1 protein was significantly lower in the cSCC and AK tissues than in the normal skin tissues ( χ2 = 44.40, P < 0.001). qRT-PCR showed that the mRNA expression level of BRG1 was significantly lower in the cSCC tissues (1.345 ± 0.956) than in the normal skin tissues (2.499 ± 1.501, t = 2.25, P = 0.035), and also significantly lower in A431 and Scl-1 cells (0.041 ± 0.002, 0.026 ± 0.003, respectively) than in HaCaT cells (0.135 ± 0.033, t = 4.95, 5.73, P = 0.008, 0.005, respectively). The low expression of BRG1 was associated with tumors at sun-exposed sites ( P = 0.041), low tumor differentiation ( P = 0.001), and high Broder′s grade ( P < 0.001) in the cSCC patients. In both A431 cells and Scl-1 cells, the BRG1 siRNA1 group and BRG1 siRNA2 group showed significantly increased numbers of cell colonies, migratory cells and invasive cells, as well as cell migration rates compared with the control siRNA group (all P < 0.05). Co-immunoprecipitation assay showed that BRG1 protein could bind to ATF2 protein in A431 and Scl-1 cells, and immunofluorescence staining showed that the two proteins were co-localized; compared with the control siRNA group, the BRG1 siRNA1 group (both A431 and Scl-1 cells) and BRG1 siRNA2 group (A431 cells) both showed increased phosphorylation and activation of ATF2 (all P < 0.05) ; in both A431 cells and Scl-1 cells, the shATF2 group showed significantly decreased numbers of cell colonies (both P = 0.001), cellular proliferative activity at 24 - 96 hours (all P < 0.001), and numbers of migratory cells and invasive cells compared with the shNC group (all P ≤ 0.001) . Conclusion:BRG1 was lowly expressed in the cSCC and AK tissues, and could inhibit the proliferation, migration, and invasion of cSCC cells; ATF2 could promote the proliferation, migration, and invasion of cSCC cells; BRG1 may exert an anti-tumor effect by interacting with ATF2 protein and inhibiting phosphorylation-dependent activation of ATF2.

NEDD4L represses prostate cancer cell proliferation via modulating PHF8 through the ubiquitin-proteasome pathway.

PURPOSE: Prostate cancer (PC) is a heterogeneous malignancy that greatly threatens man's health. E3 ubiquitin-protein ligase neural precursor cell expressed developmentally downregulated 4-like (NEDD4L) imparts an regulatory role in various malignancies. This study focused on the modulatory mechanism of NEDD4L in proliferation of prostate cancer cells (PCCs) via regulating histone demethylase plant homeodomain finger protein 8 (PHF8/KDM7B) through the ubiquitin-proteasome system. METHODS: The expression levels of NEDD4L, PHF8, H3 lysine 9 dimethylation (H3K9me2) and activating transcription factor 2 (ATF2) in PC tissues and cell lines were detected via real-time quantitative polymerase chain reaction and Western blotting. After transfection of pcDNA3.1-NEDD4L, pcDNA3.1-PHF8, and pcDNA3.1-ATF2 into PCCs, cell proliferation was assessed via the cell counting kit-8 and 5-ethynyl-2'-deoxyuridine assays. Interaction between NEDD4L and PHF8 was identified via the protein immunoprecipitation. The ubiquitination level of PHF8 was determined via the ubiquitination detection. The enrichments of H3K9me2 and PHF8 in the ATF2 promotor region were detected via the chromatin-immunoprecipitation assay. RESULTS: PHF8 and ATF2 were highly expressed while NEDD4L was poorly expressed in PC tissues and cells. NEDD4L overexpression reduced proliferation of PCCs. NEDD4Linduced degradation of PHF8 via ubiquitination. PHF8 limited the enrichment of H3K9me2 in the ATF2 promotor region and enhanced ATF2 transcription. Upregulation of PHF8 or ATF2 abolished the inhibitory role of NEDD4L in proliferation of PCCs. CONCLUSION: NEDD4L facilitated degradation of PHF8 to limit ATF2 transcription, thereby suppressing proliferation of PCCs.

Increased ATF2 expression predicts poor prognosis and inhibits sorafenib-induced ferroptosis in gastric cancer.

Sorafenib, a tyrosine kinase inhibitor, has an important antitumor effect as a ferroptosis inducer in multiple cancers, including gastric cancer (GC). However, the status of sorafenib as a ferroptosis inducer has recently been questioned. There is very limited information about the relationship between ferroptosis and ATF2, and the role of ATF2 in sorafenib-induced ferroptosis has not been studied. In this study, we investigated the role and underlying molecular mechanisms of ATF2 in sorafenib-induced ferroptosis in GC. We found that ATF2 was significantly upregulated in GC tissues and predicted a poor clinical prognosis. Silencing ATF2 significantly inhibited the malignant phenotype of GC cells. In addition, we observed that ATF2 was activated during sorafenib-induced ferroptosis in GC cells. ATF2 knockdown promoted sorafenib-induced ferroptosis, while ATF2 overexpression showed the opposite results in GC cells. Using ChIP-Seq and RNA-Seq, we identified HSPH1 as a target of ATF2 and further validated it by ChIP‒qPCR analysis. HSPH1 can interact with SLC7A11 (cystine/glutamate transporter) and increase its protein stability. Importantly, knockdown of HSPH1 partly reversed the effects caused by ATF2 overexpression on sorafenib-induced ferroptosis in GC cells. In addition, the results from the tumor xenograft model showed that ATF2 knockdown can effectively enhance sorafenib sensitivity in vivo. Collectively, our study reveals a novel mechanism by which sorafenib induces ferroptosis in GC.

Low-dose Aspirin may Prevent Preeclampsia by Inhibiting the Expression of ATF2.

AIMS: To explore the ATF2 expression of preeclampsia patients and investigate whether the level of ATF2 expression impacted the low-dose aspirin treatment of preeclampsia patients. BACKGROUND: Preeclampsia is a severe pregnancy-related hypertension disorder and refers to hypertension. OBJECTIVE: This study was designed to explore the activating transcription factor 2 (ATF2) expression of preeclampsia patients and investigate whether the level of ATF2 expression impacted the low-dose aspirin treatment of preeclampsia patients. METHODS: Firstly, we collected the plasma of normal and preeclampsia pregnancies and quantified the expressions of ATF2 by ELISA. Then we quantified the expression of the three downstream target genes of ATF2 (IL-8, IL-6 and MMP-2). Finally, we collected and quantified the interventional and observational group plasma. All data were compared by t-test (p<0.05). RESULTS: ATF2 and its target genes (IL-6, IL-8 and MMP-2) were upregulated in preeclampsia patients. In addition, ATF2 and its target genes were downregulated in the interventional group (LDA-treated group). CONCLUSION: Our results indicated that LDA could inhibit ATF2 expression in preeclampsia. It suggests that ATF2 may be a potential target of LDA in the prevention of preeclampsia.

Effects of Sijunzi decoction-containing serum on polyamine/HuR signaling pathway during IEC-6 cell proliferation / 中国药理学通报

Aim To investigate the effect of Sijunzi Decoction on mRNA and protein expression related to growth and cell cycle in polyamine/HuR signaling pathway during small intestinal epithelial cell (IEC-6) proliferation, and to explore its mechanism on intestinal mucosal injury repair. Methods Sijunzi Decoction-containing serum (SJZD) was prepared from SD rats, the expression of HuR protein in cytoplasm and nucleus was analyzed by immunofluorescence and Western blot, the mRNA level of activating transcription factor-2 (A T F - 2), JunD and cyclin dependent kinase 4 (CDK4) were determined by real-time fluorescent quantitative PCR (RT-PCR), Western blot was used to detect protein level of HuR, ATF-2, JunD and CDK4, and flow cytometry was applied to analyse cell cycle distribution. Results Compared with the control group, the mRNA and protein expression of ATF-2 and JunD decreased, while the expression of Cdk4 mRNA and protein increased in SZJD group, and the proportion of G

Activating transcription factor 2 (AccATF2) regulates tolerance to oxidative stress in Apis cerana cerana.

Activating transcription factor 2 (ATF2), a basic leucine zipper (bZIP) transcription factor, plays a crucial role in immune and DNA damage response in mammals. However, the function of ATF2 in insects remains unknown. Here, we isolated the ATF2 gene from Apis cerana cerana (AccATF2) and found that AccATF2 was a main regulator of the honeybee response to oxidative stress. Our results showed that AccATF2 was highly expressed in the head, thorax and integument. AccATF2 was expressed throughout the development period of honeybees, and the highest AccATF2 transcript level was noted in brown-eyed pupae, indicating its indispensable roles in honeybee survival. Antioxidant function analysis showed that AccATF2 expression was markedly induced in response to oxidative stress caused by various environmental stresses. AccATF2 overexpression substantially enhanced the tolerance to oxidative stress of Escherichia coli cells compared with control cells. AccATF2 knockdown significantly increased the production of malondialdehyde (MDA), the transcription of antioxidant genes and the activity of antioxidant enzymes in honeybees, suggesting that AccATF2 knockdown resulted in oxidative damage to honeybees. Moreover, AccATF2 knockdown decreased honeybee resistance to oxidative stress caused by high temperature. Overall, AccATF2 plays an important role in maintaining redox homeostasis and protecting honeybees from oxidative stress caused by various environmental stimuli. Our discoveries add to a growing understanding of how honeybees cope with various adverse environmental conditions to ensure their survival.

ANKRD49 promotes the invasion and metastasis of lung adenocarcinoma via a P38/ATF-2 signalling pathway.

Lung adenocarcinoma (LUAD) is the most challenging neoplasm to treat in clinical practice. Ankyrin repeat domain 49 protein (ANKRD49) is highly expressed in several carcinomas; however, its pattern of expression and role in LUAD are not known. Tissue microarrays, immunohistochemistry, χ2 test, Spearman correlation analysis, Kaplan-Meier, log-rank test, and Cox's proportional hazard model were used to analyse the clinical cases. The effect of ANKRD49 on the LUAD was investigated using CCK-8, clonal formation, would healing, transwell assays, and nude mice experiment. Expressions of ANKRD49 and its associated downstream protein molecules were verified by real-time PCR, Western blot, immunohistochemistry, and/or immunofluorescence analyses. ANKRD49 expression was highly elevated in LUAD. The survival rate and Cox's modelling analysis indicated that there may be an independent prognostic indicator for LUAD patients. We also found that ANKRD49 promoted the invasion and migration in both in in vitro and in vivo assays, through upregulating matrix metalloproteinase (MMP)-2 and MMP-9 activities via the P38/ATF-2 signalling pathway Our findings suggest that ANKRD49 is a latent biomarker for evaluating LUAD prognosis and promotes the metastasis of A549 cells via upregulation of MMP-2 and MMP-9 in a P38/ATF-2 pathway-dependent manner.

Phospho-proteomics identifies a critical role of ATF2 in pseudorabies virus replication.

Pseudorabies virus (PRV), an etiological agent of pseudorabies in livestock, has negatively affected the porcine industry all over the world. Epithelial cells are reported as the first site of PRV infection. However, the role of host proteins and its related signaling pathways in PRV replication is largely unclear. In this study, we performed a quantitative phosphoproteomics screening on PRV-infected porcine kidney (PK-15) epithelial cells. Totally 5723 phosphopeptides, corresponding to 2180 proteins, were obtained, and the phosphorylated states of 810 proteins were significantly different in PRV-infected cells compared with mock-infected cells (P â€‹< â€‹0.05). GO and KEGG analysis revealed that these differentially expressed phosphorylated proteins were predominantly related to RNA transport and MAPK signaling pathways. Further functional studies of NF-κB, transcription activator factor-2 (ATF2), MAX and SOS genes in MAPK signaling pathway were analyzed using RNA interference (RNAi) knockdown. It showed that only ATF2-knockdown reduces both PRV titer and viral genome copy number. JNK pathway inhibition and CRISPR/Cas9 gene knockout showed that ATF2 was required for the effective replication of PRV, especially during the biogenesis of viral genome DNA. Subsequently, by overexpression of the ATF2 gene and point mutation of the amino acid positions 69/71 of ATF2, it was further demonstrated that the phosphorylation of ATF2 promoted PRV replication. These findings suggest that ATF2 may provide potential therapeutic target for inhibiting PRV infection.