Fatty acids promote M1 polarization of monocyte-derived macrophages in healthy or ketotic dairy cows and a bovine macrophage cell line via impairing mTOR-mediated autophagy.

Excessive concentrations of free fatty acids (FFA) are the main factors causing immune dysfunction and inflammation in dairy cows with ketosis. Polarization of macrophages (the process of macrophages freely switching from one phenotype to another) into M1 or M2 phenotypes is an important event during inflammation induced by environmental stimuli. In non-ruminants, mammalian target of rapamycin (mTOR)-mediated autophagy (a major waste degradation process) regulates macrophage polarization. Thus, the objective was to unravel the role of mTOR-mediated autophagy on macrophage polarization in ketotic dairy cows. Four experiments were performed as follows: (1) In vitro differentiated monocyte-derived macrophages from healthy dairy cows or dairy cows with clinical ketosis (CK) were treated with 100 ng/mL lipopolysaccharide (LPS) and 100 ng/mL interferon-γ (IFN-γ) or 10 ng/mL interleukin-4 (IL4) and 10 ng/mL interleukin-10 (IL10) for 24 h; (2) Immortalized bovine macrophages were treated with 0, 0.3, 0.6, 1.2 mM FFA and LPS and IFN-γ or IL4 and IL10 for 24 h; (3) Macrophages were pretreated with 2 µM 4,6-dimorpholino-N-(4-nitrophenyl)-1,3,5-triazin-2-amine (MHY1485) for 30 min before treatment with LPS and IFN-γ or IL4 and IL10; (4) Macrophages were pretreated with 100 nM rapamycin (RAPA) for 2 h before treatment with LPS and IFN-γ or IL4 and IL10. Compared with healthy cows, cows with CK had a greater mean fluorescence intensity (MFI) of CD86+, but lower MFI of CD206+ and lower number of autophagosomes and autolysosomes in macrophages. Exogenous FFA treatment upregulated protein abundance of inducible nitric oxide synthase (iNOS) and mean fluorescence intensity of CD86, whereas it downregulated the protein abundance of arginase 1 (ARG1) and mean fluorescence intensity of CD206. In addition, FFA increased the p-p65/p65 protein abundance and tumor necrosis factor α (TNFA), interleukin-1B (IL1B), and interleukin-6 (IL6) mRNA abundance, but decreased LC3-phosphatidylethanolamine conjugate (LC3-II) protein abundance and autophagosomes and autolysosomes number. Pretreatment with MHY1485 promoted macrophage M1 polarization and inhibited macrophage M2 polarization via decreased mTOR-mediated autophagy. Activation of mTOR-mediated autophagy by pretreatment with RAPA attenuated the upregulation of inflammation in M1 macrophages that was induced by FFA. These data revealed that high concentrations of FFA promote macrophage M1 polarization in ketotic dairy cows via impairing mTOR-mediated autophagy.

Free Fatty Acids Induce Apoptosis of Mammary Epithelial Cells of Ketotic Dairy Cows via the Mito-ROS/NLRP3 Signaling Pathway.

Early lactation increases metabolic stress in ketotic dairy cows, leading to mitochondrial damage, apoptosis, and inflammatory response in mammary epithelial cells. The pyrin domain 3 (NLRP3) pathway involving the mitochondrial reactive oxygen species (Mito-ROS)-induced nucleotide-binding oligomerization domain-like receptor has been recognized as a key mechanism in this inflammatory response and cell apoptosis. This study aimed to elucidate the underlying regulatory mechanism of Mito-ROS-NLRP3 pathway-mediated mammary epithelial cell apoptosis in dairy cows with ketosis. Mitochondrial damage and cellular apoptotic program and NLRP3 inflammasome activation were observed in the mammary gland of ketotic cows. Similar damage was detected in MAC-T cells treated with exogenous fatty acids (FFAs). However, NLRP3 inhibitor MCC950 pretreatment or Mito-ROS scavenging by MitoTEMPO attenuated apoptosis in FFA-induced MAC-T cells by inhibiting the NLRP3 inflammasome pathway. These findings reveal that the Mito-ROS-NLRP3 pathway activation is a potent mechanism underlying mammary epithelial cell apoptosis in response to metabolic stress in ketotic dairy cows, which further contributes to reduced milk yield.

Mitochondrial Calcium Uniporter Regulator 1 (MCUR1) Relieves Mitochondrial Damage Induced by Lipopolysaccharide by Mediating Mitochondrial Ca2+ Homeostasis in Bovine Mammary Epithelial Cells.

The metabolic stress triggered by negative energy balance after calving induces mitochondrial damage of bovine mammary epithelial cells. Mitochondrial calcium uniporter regulator 1 (MCUR1) is a key protein-coding gene that mediates mitochondrial calcium ion (Ca2+) uptake and plays an important role in mediating homeostasis of mitochondria. The aim of the present study was to elucidate the effects of MCUR1-mediated Ca2+ homeostasis on mitochondria of bovine mammary epithelial cells in response to an inflammatory challenge with lipopolysaccharide (LPS). Exogenous LPS resulted in upregulation of the MCUR1 mRNA and protein abundance, mitochondrial Ca2+ content, and mitochondrial reactive oxygen species (Mito-ROS) content while decreasing mitochondrial membrane potential, causing mitochondrial damage, and increasing the rate of apoptosis. Ryanodine pretreatment attenuated the upregulation of the mitochondrial Ca2+ content and Mito-ROS content induced by LPS. Overexpression of MCUR1 increased the mitochondrial Ca2+ content and Mito-ROS content, while it decreased mitochondrial membrane potential, damaged mitochondria, and induced cell apoptosis. In addition, knockdown of MCUR1 by small interfering RNA attenuated LPS-induced mitochondrial dysfunction by inhibiting mitochondrial Ca2+ uptake. Our results revealed that exogenous LPS induces MCUR1-mediated mitochondrial Ca2+ overload in bovine mammary epithelial cells, which leads to mitochondrial injury. Thus, MCUR1-mediated Ca2+ homeostasis may be a potential therapeutic target against mitochondrial damage induced by metabolic challenges in bovine mammary epithelial cells.

Activation of PINK1-mediated mitophagy protects bovine mammary epithelial cells against lipopolysaccharide-induced mitochondrial and inflammatory damage in vitro.

Increased metabolic stress during early lactation results in damage of mitochondria and inflammatory responses in bovine mammary epithelial cells, both of which could be aggravated by inhibition of mitophagy. PTEN-induced putative kinase 1 (PINK1)-mediated mitophagy is essential in the removal of damaged mitochondria and the regulation of inflammatory responses. The aim of the present study was to elucidate the role of PINK1-mediated mitophagy on mitochondrial damage and inflammatory responses in bovine mammary epithelial cells challenged with lipopolysaccharide (LPS). Exogenous LPS activated mitophagy and led to lower protein abundance of oxidative phosphorylation (OXPHOS) complexes (COI-V) and lower oxygen consumption rate (OCR) along with increased mitochondrial reactive oxygen species (Mito-ROS) content. These effects were also associated with increased protein abundance of Nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) in a time-dependent manner. Pretreatment with 3-Methyladenine (3-MA) or knockdown of PINK1 aggravated the downregulation of COI-V protein abundance, the increase in Mito-ROS content, and the protein abundance of NLRP3, Cleaved-Caspase-1 and IL-1ß induced by LPS. Overexpression of PINK1 activated mitophagy and alleviated LPS-induced NLRP3 inflammasome activation by reducing Mito-ROS production. Overall, the data suggested that PINK1-mediated mitophagy is a crucial anti-inflammatory mechanism that removes damaged mitochondria in bovine mammary epithelial cells experiencing an increased inflammatory load.

Sirtuin 3 relieves inflammatory responses elicited by lipopolysaccharide via the PGC1α-NFκB pathway in bovine mammary epithelial cells.

Excessive inflammation in bovine mammary endothelial cells (BMEC) due to mastitis leads to disease progression and eventual culling of cattle. Sirtuin 3 (SIRT3), a mitochondrial deacetylase, downregulates pro-inflammatory cytokines in BMEC exposed to high concentrations of nonesterified fatty acids by blunting nuclear factor-κB (NFκB) signaling. In nonruminants, SIRT3 is under the control of PGC1α, a transcriptional cofactor. Specific aims were to study (1) the effect of SIRT3 on inflammatory responses of lipopolysaccharide (LPS)-challenged bovine mammary epithelial cells (bovine mammary alveolar cells-T, MAC-T) models, and (2) the role of PGC1α in the attenuation of NFκB signaling via SIRT3. To address these objectives, first, MAC-T cells were incubated in triplicate with 0, 50, 100, 150, or 200 µg/mL LPS (derived from Escherichia coli O55:B5) for 12 h with or without a 2-h incubation of the NFκB inhibitor ammonium pyrrolidine dithiocarbamate (APDC, 10 µM). Second, SIRT3 was overexpressed using adenoviral expression (Ad-SIRT3) at different multiplicity of infection (MOI) for 6 h followed by a 12 h incubation with 150 µg/mL LPS. Third, cells were treated with the PGC1α agonist ZLN005 (10 µg/mL) for 24 h and then challenged with 150 µg/mL LPS for 12 h. Fourth, cells were initially treated with the PGC1α inhibitor SR-18292 (100 µM) for 6 h followed by a 6-h culture with or without 50 MOI Ad-SIRT3 and a challenge with 150 µg/mL LPS for 12 h. Data were analyzed using one-way ANOVA with subsequent Bonferroni correction. Linear and quadratic contrasts were used to determine dose-responses to LPS. There were linear and quadratic effects of LPS dosage on cell viability. Incubation with 150 and 200 µg/mL LPS for 12 h decreased cell viability to 78.6 and 34.9%, respectively. Compared with controls, expression of IL1B, IL6, and TNFA was upregulated by 5.2-, 5.9-, and 2.7-fold with 150 µg/mL LPS; concentrations of IL-1ß, IL-6, and tumor necrosis factor-α (TNF-α) in cell medium also increased. Compared with the LPS group, LPS+APDC increased cell viability and reversed the upregulation of IL1B, IL6, and TNFA expression. However, mRNA and protein abundance of SIRT3 decreased linearly with increasing LPS dose. Ad-SIRT3 infection (50 MOI) reduced IL1B, IL6, and TNFA expression and also their concentrations in cell medium, and decreased pNFκB P65/NFκB P65 ratio and nuclear abundance of NFκB P65. The PGC1α agonist increased SIRT3 expression, whereas it decreased cytokine expression, pNFκB P65/NFκB P65 ratio, and prevented NFκB P65 nuclear translocation. Contrary to the agonist, the PGC1α inhibitor had opposite effects, and elevated the concentrations of IL-1ß, IL-6, and TNF-α in cell medium. Overall, data suggested that SIRT3 activity could attenuate LPS-induced inflammatory responses in mammary cells via alterations in the PGC1α-NFκB pathway. As such, there may be potential benefits for targeting SIRT3 in vivo to help prevent or alleviate negative effects of mastitis.

Inhibiting nuclear factor erythroid 2 related factor 2-mediated autophagy in bovine mammary epithelial cells induces oxidative stress in response to exogenous fatty acids.

BACKGROUND: In early lactation, bovine mammary epithelial cells undergo serious metabolic challenges and oxidative stress both of which could be alleviated by activation of autophagy. Nuclear factor erythroid 2 related factor 2 (NFE2L2), a master regulator of cellular redox homeostasis, plays an important role in the regulation of autophagy and oxidative stress. Thus, the objective of this study was to investigate the role of NFE2L2-mediated autophagy on oxidative stress of bovine mammary epithelial cells in response to exogenous free fatty acids (FFA). RESULTS: Exogenous FFA induced linear and quadratic decreases in activities of glutathione peroxidase (GSH-Px), catalase (CAT), and superoxide dismutase (SOD), and increases in the contents of reactive oxygen species (ROS) and malondialdehyde (MDA). Protein abundance of LC3-phosphatidylethanolamine conjugate (LC3-II) and the number of autophagosomes and autolysosomes decreased in a dose-dependent manner, while protein abundance of p62 increased in cells challenged with FFA. Activation of autophagy via pre-treatment with Rap attenuated the FFA-induced ROS accumulation. Importantly, FFA inhibited protein abundance of NFE2L2 and the translocation of NFE2L2 into the nucleus. Knockdown of NFE2L2 by siRNA decreased protein abundance of LC3-II, while it increased protein abundance of p62. Furthermore, sulforaphane (SFN) pre-treatment attenuated the FFA-induced oxidative stress by activating NFE2L2-mediated autophagy. CONCLUSIONS: The data suggested that NFE2L2-mediated autophagy is an important antioxidant mechanism in bovine mammary epithelial cells experiencing increased FFA loads.

Network Pharmacology-Based Analysis of Pogostemon cablin (Blanco) Benth Beneficial Effects to Alleviate Nonalcoholic Fatty Liver Disease in Mice.

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease and is associated with high morbidity and mortality. Pogostemon cablin (Blanco) Benth/Huo Xiang (HX) is a perennial herb with unique anti-oxidant and anti-inflammatory properties, and thus, can positively affect liver function. In this study, we used network pharmacology to predict the potential mechanism of HX on NAFLD. Pharmacological experiments were used to verify the effect of HX on the functions of NAFLD. Network pharmacology identified nine components that interacted with 82 NAFLD-related targets, revealing four target genes: TNF, IL6, TP53, and AKT1. HX prevents the development and progression of NAFLD through different pathways and targets with quercetin-regulated lipid metabolism, anti-inflammatory, and anti-oxidant pathways playing an essential role in the treatment of NAFLD. Compared with feeding HFD, HX significantly attenuated lipid accumulation in vivo with mice and also in vitro with mouse liver cells. A high dose of HX decreased hepatocyte lipid accumulation and the abundance of SREBF1 and FASN. Validation experiments revealed that HX inhibited the activation of NF-κB/IκB signaling and decreased the release and levels of pro-inflammatory factors (TNF-α and IL-6). These data suggest that HX can attenuate abnormal lipid metabolic responses and enhance antioxidant mechanisms. Thus, the pharmacological effects from plants used in traditional Chinese medicine are achievde through a multi-level response.

Nuclear factor erythroid 2-related factor 2 protects bovine mammary epithelial cells against free fatty acid-induced mitochondrial dysfunction in vitro.

Bovine mammary epithelial cells undergo an increase in metabolic rate, mitochondrial dysfunction, and oxidative stress after calving. Nuclear factor erythroid 2-related factor 2 (NFE2L2), a master regulator of cellular redox homeostasis, plays crucial roles in the regulation of mitochondrial function. The objective of this study was to investigate the role of NFE2L2 on mitochondrial function in bovine mammary epithelial cells under hyperlipidemic conditions. Three experiments were conducted as follows: (1) the immortalized bovine mammary epithelial cell line MAC-T was treated with various concentrations of free fatty acids (FFA; 0, 0.6, 1.2, or 2.4 mM) for 24 h to induce stress; (2) MAC-T cells were transfected with small interfering RNA targeting NFE2L2 (si-NFE2L2) and scrambled nontarget negative control (si-Control) for 48 h; and (3) MAC-T cells were pretreated with 10 µM sulforaphane (SFN), an activator of NFE2L2, for 24 h followed by treatment with 1.2 mM FFA for an additional 24 h. Results indicated that exogenous FFA challenge induced linear and quadratic increases in concentrations of mitochondrial reactive oxygen species (ROS). Compared with 0 mM FFA, mitochondrial membrane potential, mRNA abundance of oxidative phosphorylation complexes (CO I-V), protein abundance of nuclear respiratory factor 1 (NRF1), peroxisome proliferator-activated receptor γ coactivator 1 α (PGC-1α), mitochondrial transcription factor A (TFAM), and NFE2L2 along with the contents of ATP, mitochondrial DNA (mtDNA), and total mitochondria were greater in the MAC-T challenged with 0.6 mM FFA group, but lower in the 1.2 and 2.4 mM FFA cultures. Knockdown of NFE2L2 via small interfering RNA led to greater mitochondrial ROS content and lower mitochondrial membrane potential along with contents of ATP, mtDNA, and total mitochondria. The SFN pretreatment upregulated protein abundance of NFE2L2 and attenuated the downregulation of NFE2L2 induced by FFA. Pretreatment with SFN attenuated the downregulation induced by FFA of PGC-1α, NRF1, and TFAM protein abundance along with contents of mtDNA and total mitochondria. Furthermore, SFN pretreatment attenuated the upregulation of mitochondrial ROS content, the downregulation of mitochondrial membrane potential, and the decreases in ATP, mtDNA, and mitochondrial content induced by FFA. Overall, data indicated that FFA inhibit NFE2L2, resulting in mitochondrial dysfunction and ROS production in bovine mammary epithelial cells. Thus, NFE2L2 may be a promising therapeutic target against metabolic challenge-driven mitochondrial dysfunction and oxidative stress in bovine mammary epithelial cells.

miR­224­5p regulates the proliferation, migration and invasion of pancreatic mucinous cystadenocarcinoma by targeting PTEN.

Pancreatic mucinous cystadenocarcinoma (MCC) is a rare malignant tumor, with a limited number of studies. The present study aimed to investigate the function and mechanism of microRNA (miR)­224­5p on proliferation, migration and invasion of MCC of the pancreas. Reverse transcription­quantitative PCR was used to explorethe expression of miR­224­5p and the PTEN gene. MTT, wound healing, Transwell and tumorigenesis assays were conducted to investigate the proliferation, migration and invasion of MCC1 cells in vitro and in vivo. Western blot analysis was employed to test the protein expression of PTEN. The target gene of miR­224­5p was assessed and verified by luciferase assay. miR­224­5p expression was notably higher, while PTEN expression was lower, in MCC1 cells compared with normal tissues and cells. Overexpression of miR­224­5p promoted the proliferation, migration and invasion of MCC and knockdown of miR­224­5p inhibited these functions. Bioinformatics analysis and luciferase assay indicated that PTEN was the direct target gene of miR­224­5p. The negative correlation between miR­224­5p and PTEN was confirmed both in vitro and in vivo. PTEN reversed the effects of miR­224­5p on proliferation, migration and invasion of MCC1 cells. The present study revealed for the first time, to the best of the authors' knowledge, that miR­224­5p was highly expressed and served an oncogenic role in MCC. miR­224­5p not only regulated the proliferation, migration and invasion of pancreatic MCC but may also be a potential therapeutic target for MCC.

Transcription factor EB (TFEB)-mediated autophagy protects bovine mammary epithelial cells against H2O2-induced oxidative damage in vitro.

BACKGROUND: Bovine mammary epithelial cells after calving undergo serious metabolic challenges and oxidative stress both of which could compromise autophagy. Transcription factor EB (TFEB)-mediated autophagy is an important cytoprotective mechanism against oxidative stress. However, effects of TFEB-mediated autophagy on the oxidative stress of bovine mammary epithelial cells remain unknown. Therefore, the main aim of the study was to investigate the role of TFEB-mediated autophagy in bovine mammary epithelial cells experiencing oxidative stress. RESULTS: H2O2 challenge of the bovine mammary epithelial cell MAC-T increased protein abundance of LC3-II, increased number of autophagosomes and autolysosomes while decreased protein abundance of p62. Inhibition of autophagy via bafilomycin A1 aggravated H2O2-induced reactive oxygen species (ROS) accumulation and apoptosis in MAC-T cells. Furthermore, H2O2 treatment triggered the translocation of TFEB into the nucleus. Knockdown of TFEB by siRNA reversed the effect of H2O2 on protein abundance of LC3-II and p62 as well as the number of autophagosomes and autolysosomes. Overexpression of TFEB activated autophagy and attenuated H2O2-induced ROS accumulation. Furthermore, TFEB overexpression attenuated H2O2-induced apoptosis by downregulating the caspase apoptotic pathway. CONCLUSIONS: Our results indicate that activation of TFEB mediated autophagy alleviates H2O2-induced oxidative damage by reducing ROS accumulation and inhibiting caspase-dependent apoptosis.

Macrophage-derived EDA-A2 inhibits intestinal stem cells by targeting miR-494/EDA2R/ß-catenin signaling in mice.

The mucosa microenvironment is critical for intestinal stem cell self-renewal and reconstruction of the epithelial barrier in inflammatory bowel disease (IBD), where the mechanisms underlying cross-talk between intestinal crypts and the microenvironment remain unclear. Here, we firstly identified miR-494-3p as an important protector in colitis. miR-494-3p levels were decreased and negatively correlated with the severity in human IBD samples, as well as in colitis mice. In colitis crypts, a notable cytokine-cytokine receptor, miR-494-3p-targeted EDA2R and the ligand EDA-A2, suppressed colonic stemness and epithelial repair by inhibiting ß-catenin/c-Myc. In differentiated IECs, miR-494-3p inhibits macrophage recruitment, M1 activation and EDA-A2 secretion by targeting IKKß/NF-κB in colitis. A miR-494-3p agomir system notably ameliorated the severity of colonic colitis in vivo. Collectively, our findings uncover a miR-494-3p-mediated cross-talk mechanism by which macrophage-induced intestinal stem cell impairment aggravates intestinal inflammation.

Autophagy promotes malignant migration and invasion via miR-224-5p/BCL2 in pancreatic mucinous cystadenocarcinoma MCC1 cells.

The prognosis of invasive pancreatic mucinous cystadenocarcinoma (MCC) is poor, and the molecular mechanism underlying its development remains unclear. The present study aimed to explore the potential role of autophagy in pancreatic MCC. The results demonstrated an increase in autophagy signaling in pancreatic MCC tissues and the MCC1 cell line compared with adjacent tissues and normal human pancreatic ductal epithelium (HPDE) cells. In addition, abnormal autophagy activation facilitated the migration and invasion of MCC1 cells. MicroRNA (miR)-224-5p expression levels were significantly higher in MCC1 cells compared with those in HPDE cells. Treatment with rapamycin further demonstrated that high levels of autophagy elevated miR-224-5p expression in MCC1 cells in a time-dependent manner. BCL2 was identified as a downstream target gene of miR-224-5p, which binds to the 3'-untranslated region of BCL2. In addition, the results of the present study demonstrated that BCL2 knockdown reversed the inhibition of autophagy mediated by the miR-224-5p inhibitor. To the best of our knowledge, this is the first study to evaluate the role of autophagy in pancreatic MCC. Thus, these results suggested that autophagy may be hyperactivated in pancreatic MCC. In addition, the present study identified a positive feedback loop between autophagy signaling and miR-224-5p, which may promote the aggressive migration and invasion of MCC1. These results may provide a new insight into the relationship between autophagy and tumor metastasis in pancreatic MCC.

Chinese Herbal Formula (CHF03) Attenuates Non-Alcoholic Fatty Liver Disease (NAFLD) Through Inhibiting Lipogenesis and Anti-Oxidation Mechanisms.

Nonalcoholic fatty liver disease (NAFLD) is a hepatic ailment with a rapidly increasing incidence in the human population due largely to dietary hyper nutrition and subsequent obesity. Discovering effective natural compounds and herbs against NAFLD can provide alternative and complementary medical treatments to current chemical pharmaceuticals. In this study, ICR male mice were fed a high-fat diet (HFD) in vivo and the AML12 cells were treated with palmitic acid (PA) in vitro. We explore the protective effect and potential mechanism of Chinese Herbal Formula (CHF03) against NAFLD by HE staining, transmission Electron Microscopy assay, Western blotting, and gene expression. In vivo, oxidative stress markers (GSH, GSH-px, MDA, SOD, and CAT) confirmed that CHF03 alleviated oxidative stress and abundance of NF-κB proteins indicating a reduction in inflammation and oxidative stress. The lower protein abundance of ACACA and FASN indicated a preventive effect on lipogenesis. Histological and ultrastructural observations revealed that CHF03 inhibited NAFLD. Expression of Srebf1, Fasn, and Acaca, which are associated with lipogenesis, were downregulated. In vitro, genes and proteins are expressed in a dose-dependent manner, consistent with those in the liver. CHF03 inhibited lipid accumulation and expression of NF-κB, nuclear transfer, and transcriptional activity in AML12 cells. The CHF03 might have a beneficial role in the prevention of hepatic steatosis by altering the expression of lipogenic genes and attenuating oxidative stress.

Intestinal Barrier Function-Non-alcoholic Fatty Liver Disease Interactions and Possible Role of Gut Microbiota.

Non-alcoholic fatty liver disease (NAFLD) is a metabolic stress liver injury that is closely related to obesity, insulin resistance, type 2 diabetes, atherosclerosis, and metabolic syndrome. The pathological features are diffuse hepatic vesicular steatosis, including non-alcoholic steatohepatitis, liver fibrosis, and even liver cancer. A variety of pathological outcomes cause serious harm to human health. At present, an increasing number of researchers are investigating the pathogenesis of NAFLD from the perspective of changes in the function of the intestinal barrier. The physical, chemical, immunological, and microbiological barriers in the intestinal tract constitute the complete intestinal barrier, which plays an important defensive role against the invasion of harmful substances from the intestines. Protecting the function of the intestinal barrier is a new way to treat NAFLD and its related diseases. In this perspective, we summarized the current knowledge of the role of the intestinal barrier in NAFLD.

RUNX proteins desensitize multiple myeloma to lenalidomide via protecting IKZFs from degradation.

Ikaros family zinc finger protein 1 and 3 (IKZF1 and IKZF3) are transcription factors that promote multiple myeloma (MM) proliferation. The immunomodulatory imide drug (IMiD) lenalidomide promotes myeloma cell death via Cereblon (CRBN)-dependent ubiquitylation and proteasome-dependent degradation of IKZF1 and IKZF3. Although IMiDs have been used as first-line drugs for MM, the overall survival of refractory MM patients remains poor and demands the identification of novel agents to potentiate the therapeutic effect of IMiDs. Using an unbiased screen based on mass spectrometry, we identified the Runt-related transcription factor 1 and 3 (RUNX1 and RUNX3) as interactors of IKZF1 and IKZF3. Interaction with RUNX1 and RUNX3 inhibits CRBN-dependent binding, ubiquitylation, and degradation of IKZF1 and IKZF3 upon lenalidomide treatment. Inhibition of RUNXs, via genetic ablation or a small molecule (AI-10-104), results in sensitization of myeloma cell lines and primary tumors to lenalidomide. Thus, RUNX inhibition represents a valuable therapeutic opportunity to potentiate IMiDs therapy for the treatment of multiple myeloma.

Loss of Wwox drives metastasis in triple-negative breast cancer by JAK2/STAT3 axis.

Loss of WW domain-containing oxidoreductase (Wwox) expression has been observed in breast cancer (BC). However, its regulatory effects are largely unknown, especially in triple-negative breast cancer (TNBC). Herein, gene expression profiling revealed that JAK/STAT3 pathway was one of the most differentially modulated pathways in basal-like BC cells. The lower expression of Wwox was significantly correlated with high activation of STAT3 in basal-like cells and TNBC tissues. Overexpression of Wwox markedly inhibited proliferation and metastasis of BC cells by suppressing STAT3 activation, which is to interact with JAK2 to inhibit JAK2 and STAT3 phosphorylation. Furthermore, Wwox limited STAT3 binding to the interleukin-6 promoter, repressing expression of the IL-6 cytokine. Altogether, our data established that Wwox suppresses BC cell metastasis and proliferation by JAK2/STAT3 pathway. Targeting of Wwox with STAT3 could offer a promising therapeutic strategy for TNBC.

LKB1 obliterates Snail stability and inhibits pancreatic cancer metastasis in response to metformin treatment.

Metastasis to distant organs is a particularly ominous feature of malignant cancer. LKB1 (also known as STK11) has been identified as a tumor suppressor in several types of cancers. Here, we show that LKB1 is at low levels and is negatively associated with poor clinical outcomes in pancreatic cancer (PC). LKB1 is inversely correlated with Snail protein in PC, in which the loss of LKB1 facilitates metastasis through elevating Snail protein level. Furthermore, LKB1 boosts Snail's interaction with E3 ligase FBXL14, leading to increasing ubiquitin-mediated Snail degradation. Notably, metformin could increase Snail protein ubiquitination via augmenting the location of LKB1 at cytoplasm as well as increasing LKB1 expression. Altogether, our data established that LKB1 impedes invasion and metastasis by decreasing the Snail protein level in PC. Targeting the LKB1/FBXL14/Snail axis may represent a promising therapeutic strategy and metformin might be beneficial for PC therapy through activating the LKB1-mediated Snail ubiquitination pathway.

SORBS1 suppresses tumor metastasis and improves the sensitivity of cancer to chemotherapy drug.

Tumor metastasis and invasion are both hallmarks of cancer malignancy and the leading cause of cancer death. Here we show that the adaptor protein SORBS1 (Sorbin and SH3 domain-containing protein 1, also known as CAP/ponsin) is expressed at low levels in clinical cancer samples. In addition, low-level expression of SORBS1 was significantly associated with poor clinical outcomes and the increased tumor cell invasive capacity in breast cancer patients. We demonstrate that depletion of SORBS1 increases protrusions and filopodium-like protrusions (FLPs) formation, as well as the migratory and invasive abilities of cancer cells, via activation of JNK/cJun. Furthermore, silencing of SORBS1 promotes the epithelial-to-mesenchymal transition (EMT) process and attenuates chemical drug sensitivity especially that to cisplatin, by inhibition of p53 in breast cancer cells. Thus, we illustrate that SORBS1 is a potential inhibitor of metastasis in cancer and may be a promising target in chemotherapy.

Loss of Scribble Promotes Snail Translation through Translocation of HuR and Enhances Cancer Drug Resistance.

Drug resistance of cancer cells to various therapeutic agents and molecular targets is a major problem facing current cancer research. The tumor suppressor gene Scribble encodes a polarity protein that is conserved between Drosophila and mammals; loss of the locus disrupts cell polarity, inhibits apoptosis, and mediates cancer process. However, the role of Scribble in drug resistance remains unknown. We show here that knockdown of Scribble enhances drug resistance by permitting accumulation of Snail, which functions as a transcription factor during the epithelial-mesenchymal transition. Then, loss of Scribble activates the mRNA-binding protein human antigen R (HuR) by facilitating translocation of HuR from the nucleus to the cytoplasm. Furthermore, we demonstrate HuR can recognize AU-rich elements of the Snail-encoding mRNA, thereby regulating Snail translation. Moreover, loss of Scribble-induced HuR translocation mediates the accumulation of Snail via activation of the p38 MAPK pathway. Thus, this work clarifies the role of polarity protein Scribble, which is directly implicated in the regulation of developmental transcription factor Snail, and suggesting a mechanism for Scribble mediating cancer drug resistance.

Loss of polarity protein AF6 promotes pancreatic cancer metastasis by inducing Snail expression.

Pancreatic cancer (PC) is a particularly lethal form of cancer with high potential for metastasis to distant organs. Disruption of cell polarity is a hallmark of advanced epithelial tumours. Here we show that the polarity protein AF6 (afadin and MLLT4) is expressed at low levels in PC. We demonstrate that depletion of AF6 markedly promotes proliferation and metastasis of PC cells through upregulation of the expression of Snail protein, and this requires the nuclear localization of AF6. Furthermore, AF6 deficiency in PC cells leads to increased formation of a Dishevelled 2 (Dvl2)-FOXE1 complex on the promoter region of Snail gene, and activation of Snail expression. Altogether, our data established AF6 as a potential inhibitor of metastasis in PC cells. Targeting the Dvl2-FOXE1-Snail signalling axis may thus represent a promising therapeutic strategy.