MiR-574-5p activates human TLR8 to promote autoimmune signaling and lupus.

Endosomal single-stranded RNA-sensing Toll-like receptor-7/8 (TLR7/8) plays a pivotal role in inflammation and immune responses and autoimmune diseases. However, the mechanisms underlying the initiation of the TLR7/8-mediated autoimmune signaling remain to be fully elucidated. Here, we demonstrate that miR-574-5p is aberrantly upregulated in tissues of lupus prone mice and in the plasma of lupus patients, with its expression levels correlating with the disease activity. miR-574-5p binds to and activates human hTLR8 or its murine ortholog mTlr7 to elicit a series of MyD88-dependent immune and inflammatory responses. These responses include the overproduction of cytokines and interferons, the activation of STAT1 signaling and B lymphocytes, and the production of autoantigens. In a transgenic mouse model, the induction of miR-574-5p overexpression is associated with increased secretion of antinuclear and anti-dsDNA antibodies, increased IgG and C3 deposit in the kidney, elevated expression of inflammatory genes in the spleen. In lupus-prone mice, lentivirus-mediated silencing of miR-574-5p significantly ameliorates major symptoms associated with lupus and lupus nephritis. Collectively, these results suggest that the miR-574-5p-hTLR8/mTlr7 signaling is an important axis of immune and inflammatory responses, contributing significantly to the development of lupus and lupus nephritis.

Androgen Receptor Transcriptionally Inhibits Programmed Death Ligand-1 Expression and Influences Immune Escape in Bladder Cancer.

In multiple clinical trials, immune checkpoint blockade-based immunotherapy has shown significant therapeutic efficacy in bladder cancer (BCa). Sex is closely related to the incidence rate and prognosis of BCa. As one of the sex hormone receptors, the androgen receptor (AR) is a well-known key regulator that promotes the progression of BCa. However, the regulatory mechanism of AR in the immune response of BCa is still unclear. In this study, the expression of AR and programmed death ligand 1 (PD-L1) was negatively correlated in BCa cells, clinical tissues, and tumor data extracted from The Cancer Genome Atlas Bladder Urothelial Carcinoma cohort. A human BCa cell line was transfected to alter the expression of AR. The results show that AR negatively regulated PD-L1 expression by directly binding to AR response elements on the PD-L1 promoter region. In addition, AR overexpression in BCa cells significantly enhanced the antitumor activity of cocultured CD8+ T cells. Injection of anti-PD-L1 monoclonal antibodies into C3H/HeN mice significantly suppressed tumor growth, and stable expression of AR dramatically enhanced the antitumor activity in vivo. In conclusion, this study describes a novel role of AR in regulating the immune response to BCa by targeting PD-L1, thus providing potential therapeutic strategies for immunotherapy in BCa.

Multi-Omics Comparison of the Spontaneous Diabetes Mellitus and Diet-Induced Prediabetic Macaque Models.

The prevalence of diabetes mellitus has been increasing for decades worldwide. To develop safe and potent therapeutics, animal models contribute a lot to the studies of the mechanisms underlying its pathogenesis. Dietary induction using is a well-accepted protocol in generating insulin resistance and diabetes models. In the present study, we reported the multi-omics profiling of the liver and sera from both peripheral blood and hepatic portal vein blood from Macaca fascicularis that spontaneously developed Type-2 diabetes mellitus with a chow diet (sDM). The other two groups of the monkeys fed with chow diet and high-fat high-sugar (HFHS) diet, respectively, were included for comparison. Analyses of various omics datasets revealed the alterations of high consistency. Between the sDM and HFHS monkeys, both the similar and unique alterations in the lipid metabolism have been demonstrated from metabolomic, transcriptomic, and proteomic data repeatedly. The comparison of the proteome and transcriptome confirmed the involvement of fatty acid binding protein 4 (FABP4) in the diet-induced pathogenesis of diabetes in macaques. Furthermore, the commonly changed genes between spontaneous diabetes and HFHS diet-induced prediabetes suggested that the alterations in the intra- and extracellular structural proteins and cell migration in the liver might mediate the HFHS diet induction of diabetes mellitus.

SUCLA2-coupled regulation of GLS succinylation and activity counteracts oxidative stress in tumor cells.

Glutaminase regulates glutaminolysis to promote cancer cell proliferation. However, the mechanism underlying glutaminase activity regulation is largely unknown. Here, we demonstrate that kidney-type glutaminase (GLS) is highly expressed in human pancreatic ductal adenocarcinoma (PDAC) specimens with correspondingly upregulated glutamine dependence for PDAC cell proliferation. Upon oxidative stress, the succinyl-coenzyme A (CoA) synthetase ADP-forming subunit ß (SUCLA2) phosphorylated by p38 mitogen-activated protein kinase (MAPK) at S79 dissociates from GLS, resulting in enhanced GLS K311 succinylation, oligomerization, and activity. Activated GLS increases glutaminolysis and the production of nicotinamide adenine dinucleotide phosphate (NADPH) and glutathione, thereby counteracting oxidative stress and promoting tumor cell survival and tumor growth in mice. In addition, the levels of SUCLA2 pS79 and GLS K311 succinylation, which were mutually correlated, were positively associated with advanced stages of PDAC and poor prognosis for patients. Our findings reveal critical regulation of GLS by SUCLA2-coupled GLS succinylation regulation and underscore the regulatory role of metabolites in glutaminolysis and PDAC development.

The ubiquitination ligase SMURF2 reduces aerobic glycolysis and colorectal cancer cell proliferation by promoting ChREBP ubiquitination and degradation.

The glucose-responsive transcription factor carbohydrate response element-binding protein (ChREBP) critically promotes aerobic glycolysis and cell proliferation in colorectal cancer cells. It has been reported that ubiquitination may be important in the regulation of ChREBP protein levels and activities. However, the ChREBP-specific E3 ligase and molecular mechanism of ChREBP ubiquitination remains unclear. Using database exploration and expression analysis, we found here that levels of the E3 ligase SMURF2 (Smad-ubiquitination regulatory factor 2) negatively correlate with those of ChREBP in cancer tissues and cell lines. We observed that SMURF2 interacts with ChREBP and promotes ChREBP ubiquitination and degradation via the proteasome pathway. Interestingly, ectopic SMURF2 expression not only decreased ChREBP levels but also reduced aerobic glycolysis, increased oxygen consumption, and decreased cell proliferation in colorectal cancer cells. Moreover, SMURF2 knockdown increased aerobic glycolysis, decreased oxygen consumption, and enhanced cell proliferation in these cells, mostly because of increased ChREBP accumulation. Furthermore, we identified Ser/Thr kinase AKT as an upstream suppressor of SMURF2 that protects ChREBP from ubiquitin-mediated degradation. Taken together, our results indicate that SMURF2 reduces aerobic glycolysis and cell proliferation by promoting ChREBP ubiquitination and degradation via the proteasome pathway in colorectal cancer cells. We conclude that the SMURF2-ChREBP interaction might represent a potential target for managing colorectal cancer.

Advanced glycation end products promote ChREBP expression and cell proliferation in liver cancer cells by increasing reactive oxygen species.

The aim of the study was to elucidate the mechanism by which advanced glycation end products (AGEs) promote cell proliferation in liver cancer cells.We treated liver cancer HepG2 cells with 200 mg/L AGEs or bovine serum albumin (BSA) and assayed for cell viability, cell cycle, and apoptosis. We performed real-time PCR and Western blot analysis for RNA and protein levels of carbohydrate responsive element-binding protein (ChREBP) in AGEs- or BSA-treated HepG2 cells. We analyzed the level of reactive oxygen species (ROS) in HepG2 cells treated with AGEs or BSA.We found that increased S-phase cell percentage and decreased apoptosis contributed to AGEs-induced liver cancer cell proliferation. Real-time PCR and Western blot analysis showed that AGEs stimulated RNA and protein levels of ChREBP, a transcription factor promoting glycolysis and maintaining cell proliferation in liver cancer cells. Intriguingly, the level of ROS was higher in AGEs-treated liver cancer cells. Treating liver cancer cells with antioxidant N-acetyl cystein (NAC) partly blocked AGEs-induced ChREBP expression and cell proliferation.Our results suggest that the AGEs-ROS-ChREBP pathway plays a critical role in promoting ChREBP expression and liver cancer cell proliferation.

Advanced glycation end products increase carbohydrate responsive element binding protein expression and promote cancer cell proliferation.

Diabetic patients have increased levels of advanced glycation end products (AGEs) and the role of AGEs in regulating cancer cell proliferation is unclear. Here, we found that treating colorectal and liver cancer cells with AGEs promoted cell proliferation. AGEs stimulated both the expression and activation of a key transcription factor called carbohydrate responsive element binding protein (ChREBP) which had been shown to promote glycolytic and anabolic activity as well as proliferation of colorectal and liver cancer cells. Using siRNAs or the antagonistic antibody for the receptor for advanced glycation end-products (RAGE) blocked AGEs-induced ChREBP expression or cell proliferation in cancer cells. Suppressing ChREBP expression severely impaired AGEs-induced cancer cell proliferation. Taken together, these results demonstrate that AGEs-RAGE signaling enhances cancer cell proliferation in which AGEs-mediated ChREBP induction plays an important role. These findings may provide new explanation for increased cancer progression in diabetic patients.

Flightless I homolog negatively regulates ChREBP activity in cancer cells.

The glucose-responsive transcription factor carbohydrate responsive element binding protein (ChREBP) plays an important role in regulating glucose metabolism in support of anabolic synthesis in both hepatocytes and cancer cells. In order to further investigate the molecular mechanism by which ChREBP regulates transcription, we used a proteomic approach to identify proteins interacting with ChREBP. We found several potential ChREBP-interacting partners, one of which, flightless I homolog (FLII) was verified to interact and co-localize with ChREBP in HCT116 colorectal cancer and HepG2 hepatocellular carcinoma cells. FLII is a member of the gelsolin superfamily of actin-remodeling proteins and can function as a transcriptional co-regulator. The C-terminal 227 amino acid region of ChREBP containing the DNA-binding domain interacted with FLII. Both the N-terminal leucine-rich repeat (LRR) domain and C-terminal gelsolin homolog domain (GLD) of FLII interacted and co-localized with ChREBP. ChREBP and FLII localized in both the cytoplasm and nucleus of cancer cells. Glucose increased expression and nuclear localization of ChREBP, and had minimal effect on the level and distribution of FLII. FLII knockdown using siRNAs increased mRNA and protein levels of ChREBP-activated genes and decreased transcription of ChREBP-repressed genes in cancer cells. Conversely, FLII overexpression negatively regulated ChREBP-mediated transcription in cancer cells. Our findings suggest that FLII is a component of the ChREBP transcriptional complex and negatively regulates ChREBP function in cancer cells.