Gene deletion of Interleukin-1α reduces ER stress-induced CHOP expression in macrophages and attenuates the progression of atherosclerosis in apoE-deficient mice.

The pathophysiology of atherosclerosis initiation and progression involves many inflammatory cytokines, one of them is interleukin (IL)-1α that has been shown to be secreted by activated macrophages. We have previously shown that IL-1α from bone marrow-derived cells is critical for early atherosclerosis development in mice. It is known that endoplasmic reticulum (ER) stress in macrophages is involved in progression to more advanced atherosclerosis, but it is still unknown whether this effect is mediated through cytokine activation or secretion. We previously demonstrated that IL-1α is required in ER stress-induced activation of inflammatory cytokines in hepatocytes and in the associated induction of steatohepatitis. In the current study, we aimed to examine the potential role of IL-1α in ER stress-induced activation of macrophages, which is relevant to progression of atherosclerosis. First, we demonstrated that IL-1α is required for atherosclerosis development and progression in the apoE knockout (KO) mouse model of atherosclerosis. Next, we showed that ER stress in mouse macrophages results in the protein production and secretion of IL-1α in a dose-dependent manner, and that IL-1α is required in ER stress-induced production of the C/EBP homologous protein (CHOP), a critical step in ER stress-mediated apoptosis. We further demonstrated that IL-1α-dependent CHOP production in macrophages is specifically mediated through the PERK-ATF4 signaling pathway. Altogether, these findings highlight IL-1α as a potential target for prevention and treatment of atherosclerotic cardiovascular disease.

Second pregnancy following kidney transplantation is not associated with an increased risk of graft loss in a single center retrospective cohort study.

INTRODUCTION: Previous studies on first pregnancy following kidney transplantation (KT) show no association with decreased graft survival. This study examined patients with multiple gestations compared to a single pregnancy following KT and evaluated the risk of graft function deterioration. METHODS: A retrospective cohort study on fertile female kidney transplant recipients (KTRs) from Rabin Medical Center between January 2001 and December 2017 was performed. Data were collected on patients' comorbidities, pregnancy complications, graft loss, mortality, and lab results. Time-varying COX analysis was performed - second pregnancy being the time-related variable. RESULTS: Fifty-two KTRs split into 30 single pregnancy and 22 multiple pregnancy patients following KT. Single pregnancy patients were older during their first pregnancy and had a higher caesarian section rate. During a median follow-up period of 5.6 years, multiple pregnancies, compared to a single pregnancy, were not associated with an increased rate of graft loss. No significant difference was seen between first and second pregnancy in gestational age, birth weight, graft function, and proteinuria rates. CONCLUSIONS: Second pregnancy following KT was not shown to be associated with a decreased graft survival. In addition, obstetrical, maternal, and fetal complication rates are not increased in second compared to first pregnancy following KT.

Targeting purine synthesis in ASS1-expressing tumors enhances the response to immune checkpoint inhibitors.

Argininosuccinate synthase (ASS1) downregulation in different tumors has been shown to support cell proliferation and yet, in several common cancer subsets ASS1 expression associates with poor patient prognosis. Here we demonstrate that ASS1 expression under glucose deprivation is induced by c-MYC, providing survival benefit by increasing nitric oxide synthesis and activating the gluconeogenic enzymes pyruvate carboxylase and phosphoenolpyruvate carboxykinase by S-nitrosylation. The resulting increased flux through gluconeogenesis enhances serine, glycine and subsequently purine synthesis. Notably, high ASS1-expressing breast cancer mice do not respond to immune checkpoint inhibitors and patients with breast cancer with high ASS1 have more metastases. We further find that inhibiting purine synthesis increases pyrimidine to purine ratio, elevates expression of the immunoproteasome and significantly enhances the response of autologous primary CD8+ T cells to anti-PD-1. These results suggest that treating patients with high-ASS1 cancers with purine synthesis inhibition is beneficial and may also sensitize them to immune checkpoint inhibition therapy.

Acid-Induced Downregulation of ASS1 Contributes to the Maintenance of Intracellular pH in Cancer.

Downregulation of the urea cycle enzyme argininosuccinate synthase (ASS1) by either promoter methylation or by HIF1α is associated with increased metastasis and poor prognosis in multiple cancers. We have previously shown that in normoxic conditions, ASS1 downregulation facilitates cancer cell proliferation by increasing aspartate availability for pyrimidine synthesis by the enzyme complex CAD. Here we report that in hypoxia, ASS1 expression in cancerous cells is downregulated further by HIF1α-mediated induction of miR-224-5p, making the cells more invasive and dependent on upstream substrates of ASS1 for survival. ASS1 was downregulated under acidic conditions, and ASS1-depleted cancer cells maintained a higher intracellular pH (pHi), depended less on extracellular glutamine, and displayed higher glutathione levels. Depletion of substrates of urea cycle enzymes in ASS1-deficient cancers decreased cancer cell survival. Thus, ASS1 levels in cancer are differentially regulated in various environmental conditions to metabolically benefit cancer progression. Understanding these alterations may help uncover specific context-dependent cancer vulnerabilities that may be targeted for therapeutic purposes. SIGNIFICANCE: Cancer cells in an acidic or hypoxic environment downregulate the expression of the urea cycle enzyme ASS1, which provides them with a redox and pH advantage, resulting in better survival.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/3/518/F1.large.jpg.

Rewiring urea cycle metabolism in cancer to support anabolism.

Cancer cells reprogramme metabolism to maximize the use of nitrogen and carbon for the anabolic synthesis of macromolecules that are required during tumour proliferation and growth. To achieve this aim, one strategy is to reduce catabolism and nitrogen disposal. The urea cycle (UC) in the liver is the main metabolic pathway to convert excess nitrogen into disposable urea. Outside the liver, UC enzymes are differentially expressed, enabling the use of nitrogen for the synthesis of UC intermediates that are required to accommodate cellular needs. Interestingly, the expression of UC enzymes is altered in cancer, revealing a revolutionary mechanism to maximize nitrogen incorporation into biomass. In this Review, we discuss the metabolic benefits underlying UC deregulation in cancer and the relevance of these alterations for cancer diagnosis and therapy.

Arginine and the metabolic regulation of nitric oxide synthesis in cancer.

Nitric oxide (NO) is a signaling molecule that plays important roles in diverse biological processes and thus its dysregulation is involved in the pathogenesis of various disorders. In cancer, NO has broad and sometimes dichotomous roles; it is involved in cancer initiation and progression, but also restricts cancer proliferation and invasion, and contributes to the anti-tumor immune response. The importance of NO in a range of cellular processes is exemplified by its tight spatial and dosage control at multiple levels, including via its transcriptional, post-translational and metabolic regulation. In this Review, we focus on the regulation of NO via the synthesis and availability of its precursor, arginine, and discuss the implications of this metabolic regulation for cancer biology and therapy. Despite the established contribution of NO to cancer pathogenesis, the implementation of NO-related cancer therapeutics remains limited, likely due to the challenge of targeting and inducing its protective functions in a cell- and dosage-specific manner. A better understanding of how arginine regulates the production of NO in cancer might thus support the development of anti-cancer drugs that target this key metabolic pathway, and other metabolic pathways involved in NO production.

Urea Cycle Dysregulation Generates Clinically Relevant Genomic and Biochemical Signatures.

The urea cycle (UC) is the main pathway by which mammals dispose of waste nitrogen. We find that specific alterations in the expression of most UC enzymes occur in many tumors, leading to a general metabolic hallmark termed "UC dysregulation" (UCD). UCD elicits nitrogen diversion toward carbamoyl-phosphate synthetase2, aspartate transcarbamylase, and dihydrooratase (CAD) activation and enhances pyrimidine synthesis, resulting in detectable changes in nitrogen metabolites in both patient tumors and their bio-fluids. The accompanying excess of pyrimidine versus purine nucleotides results in a genomic signature consisting of transversion mutations at the DNA, RNA, and protein levels. This mutational bias is associated with increased numbers of hydrophobic tumor antigens and a better response to immune checkpoint inhibitors independent of mutational load. Taken together, our findings demonstrate that UCD is a common feature of tumors that profoundly affects carcinogenesis, mutagenesis, and immunotherapy response.

Dual Regulatory Role of Polyamines in Adipogenesis.

Adipogenesis is a complex process, accompanied by a chain of interdependent events. Disruption of key events in this cascade may interfere with the correct formation of adipose tissue. Polyamines were demonstrated necessary for adipogenesis; however, the underlying mechanism by which they act has not been established. Here, we examined the effect of polyamine depletion on the differentiation of 3T3-L1 preadipocytes. Our results demonstrate that polyamines are required early in the adipogenic process. Polyamine depletion inhibited the second division of the mitotic clonal expansion (MCE), and inhibited the expression of PPARγ and C/EBPα, the master regulators of adipogenesis. However, it did not affect the expression of their transcriptional activator, C/EBPß. Additionally, polyamine depletion resulted in elevation of mRNA and protein levels of the stress-induced C/EBP homologous protein (CHOP), whose dominant negative function is known to inhibit C/EBPß DNA binding activity. Conditional knockdown of CHOP in polyamine-depleted preadipocytes restored PPARγ and C/EBPα expression, but failed to recover MCE and differentiation. Thus, our results suggest that the need for MCE in the adipogenic process is independent from the requirement for PPARγ and C/EBPα expression. We conclude that de novo synthesis of polyamines during adipogenesis is required for down-regulation of CHOP to allow C/EBPß activation, and for promoting MCE.

c-Abl forces YAP to switch sides.

Cancer research has been significantly accelerated by viewing cancer as a functional collision between 2 dichotomous sets of genes: oncogenes and tumor suppressors. Signaling pathways turn oncogenes and tumor suppressors on and off to dictate cell fate decisions. We contend that signaling also dictates opposing behaviors of a given effector.

c-Abl tyrosine kinase promotes adipocyte differentiation by targeting PPAR-gamma 2.

Adipocyte differentiation, or adipogenesis, is a complex and highly regulated process. A recent proteomic analysis has predicted that the nonreceptor tyrosine kinase Abelson murine leukemia viral oncogene (c-Abl) is a putative key regulator of adipogenesis, but the underlying mechanism remained obscure. We found that c-Abl was activated during the early phase of mouse 3T3-L1 preadipocyte differentiation. Moreover, c-Abl activity was essential and its inhibition blocked differentiation to mature adipocytes. c-Abl directly controlled the expression and activity of the master adipogenic regulator peroxisome proliferator-activator receptor gamma 2 (PPARγ2). PPARγ2 physically associated with c-Abl and underwent phosphorylation on two tyrosine residues within its regulatory activation function 1 (AF1) domain. We demonstrated that this process positively regulates PPARγ2 stability and adipogenesis. Remarkably, c-Abl binding to PPARγ2 required the Pro12 residue that has a phenotypically well-studied common human genetic proline 12 alanine substitution (Pro12Ala) polymorphism. Our findings establish a critical role for c-Abl in adipocyte differentiation and explain the behavior of the known Pro12Ala polymorphism.

Targeting ErbB-1 and ErbB-4 in irradiated head and neck cancer: results of in vitro and in vivo studies.

BACKGROUND: ErbB oncogenes have a major role in cancer. The role of ErbB-4 in cancer cell biology and the effect of anti-ErbB-1 and anti-ErbB-4 monoclonal antibodies were evaluated in this study. METHODS: ErbB-4 expression and binding was evaluated by Western blot, enzyme-linked immunosorbent assay (ELISA), fluorescent microscopy, and flow cytometry. Cell survival was measured by XTT assay. Tumor progression was followed up in nude mice model. RESULTS: High ErbB-1 levels in head and neck cancer cell lines were determined, whereas ErbB-4 expression varied. Specific antibody binding to the cells was demonstrated. High ErbB-4 expressing squamous cell carcinoma 1 (SCC-1) cells proliferated faster and generated faster growing tumors in mice. Cetuximab and mAb-3 reduced cell survival proportional to ErbB-1 and ErbB-4 expression. Combination of antibodies with irradiation was most effective in reducing cell survival and tumor growth. CONCLUSION: ErbB-4 plays a role in head and neck cancer cell biology. Anti-ErbB-4 targeted therapy can serve as a new strategy against head and neck cancer when combined with established treatments.

Diagnostic and prognostic significance of serum C-reactive protein levels in patients admitted to the department of medicine.

BACKGROUND: : Despite its apparent role as a marker of different disease processes, to date, no study has presented comprehensive comparative data regarding the distribution of serum C-reactive protein (CRP) levels in all admitted patients. We aimed to examine the distribution of serum CRP levels in internal medicine patients and to find whether initial serum CRP value had a diagnostic and prognostic significance. METHODS: : Serum CRP levels together with epidemiologic, clinical, and laboratory data were analyzed for 370 consecutive adult patients admitted to the department of internal medicine during a 2-month period. RESULTS: : The median CRP level on admission was 24 mg/L, with a range between 0 and 346 mg/L. Infections had significantly higher median CRP than noninfections (99 versus 11 mg/L), and bacterial infections had distinctively higher CRP (120 mg/L) compared with nonbacterial infections (32 mg/L). The highest noninfectious median CRP was recorded in inflammatory bowel disease exacerbation (107 mg/L). Moreover, serum CRP was divided into 5 ranges. Very high CRP >200 mg/L was a marker of sepsis. In contrast, low CRP range (<10 mg/L) was characteristic to cardiovascular diseases and viral infections, but included none of the patients with severe infections or sepsis. Furthermore, higher CRP was significantly associated with mortality, the need for intubation, and longer hospitalization, and had better distinguishing ability compared with erythrocyte sedimentation rate or platelets count for the comparison of major disease categories, such as bacterial infections, inflammatory and rheumatic disease, viral infections, and cardiovascular disorders. CONCLUSIONS: : Initial serum CRP has an important role as a diagnostic and prognostic tool in patients admitted to internal medicine.