Serum levels of polyamine synthesis enzymes increase in diabetic patients with breast cancer

Predicting Survival Signature of Bladder Cancer Related to Cancer-Associated Fibroblast (CAF) Constructed by Intersecting Genes in TCGA and GEO

Bladder cancer was one of the most common carcinomas around the world. However, the mechanism of the disease still remained to be investigated. We expected to establish a prognostic survival model with 9 prognostic genes to predict overall survival (OS) in patients of bladder cancer. The gene expression data of bladder cancer were obtained from TCGA and GEO datasets. TCGA and GEO datasets were used for screening prognostic genes along with developing and validating a 9-gene prognostic survival model by method of weighted gene co-expression network analysis (WGCNA) and LASSO with Cox regression. The relative analysis of evaluate tumor burden mutation (TBM), GO, KEGG, chemotherapy drug and functional pathway were also performed based on CAF-related mRNAs. 151 Overlapping CAF-related genes were distinguished after intersecting differentially expressed genes from 945 genes in TCGA and 491 genes in GEO dataset. 9 Prognostic genes (MSRB2, AGMAT, KLF6, DDAH2, GADD45B, SERPINE2, STMN3, TEAD2, and COMP) were used for construction of prognostic model after LASSO with Cox regression. Receiver operating characteristic (ROC) curves showed a good survival prediction by this model. Functional analysis indicated chemokine, cytokine, ECM interaction, oxidative stress and apoptosis were highly appeared. Potential drugs targeted different CAF-related genes like vemurafenib, irofulven, ghiotepa, and idarubicin were found as well. We constructed a novel 9 CAF-related mRNAs prognostic model and explored the gene expression and potential functional information of related genes, which might be worthy of clinical application. In addition, potential chemotherapy drugs could provide useful insights into the potential clinical treatment of bladder cancer.

Identification of a polyamine-related signature and six novel prognostic biomarkers in oral squamous cell carcinoma

Elevated polyamine levels are required for tumor transformation and development; however, expression patterns of polyamines and their diagnostic potential have not been investigated in oral squamous cell carcinoma (OSCC), and its impact on prognosis has yet to be determined. A total of 440 OSCC samples and clinical data were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). Consensus clustering was conducted to classify OSCC patients into two subgroups based on the expression of the 17 polyamine regulators. Polyamine-related differentially expressed genes (PARDEGs) among distinct polyamine clusters were determined. To create a prognostic model, PARDEGs were examined in the training cohorts using univariate-Lasso-multivariate Cox regression analyses. Six prognostic genes, namely, "CKS2," "RIMS3," "TRAC," "FMOD," CALML5," and "SPINK7," were identified and applied to develop a predictive model for OSCC. According to the median risk score, the patients were split into high-risk and low-risk groups. The predictive performance of the six gene models was proven by the ROC curve analysis of the training and validation cohorts. Kaplan-Meier curves revealed that the high-risk group had poorer prognosis. Furthermore, the low-risk group was more susceptible to four chemotherapy drugs according to the IC50 of the samples computed by the "pRRophetic" package. The correlation between the risk scores and the proportion of immune cells was calculated. Meanwhile, the tumor mutational burden (TMB) value of the high-risk group was higher. Real-time quantitative polymerase chain reaction was applied to verify the genes constructing the model. The possible connections of the six genes with various immune cell infiltration and therapeutic markers were anticipated. In conclusion, we identified a polyamine-related prognostic signature, and six novel biomarkers in OSCC, which may provide insights to identify new treatment targets for OSCC.

Probiotic induced synthesis of microbiota polyamine as a nutraceutical for metabolic syndrome and obesity-related type 2 diabetes

The gut microbiota regulates multiple facets of host metabolism and immunity through the production of signaling metabolites, such as polyamines which are small organic compounds that are essential to host cell growth and lymphocyte activation. Polyamines are most abundant in the intestinal lumen, where their synthesis by the gut microbiota is influenced by microbiome composition and host diet. Disruption of the host gut microbiome in metabolic syndrome and obesity-related type 2 diabetes (obesity/T2D) results in potential dysregulation of polyamine synthesis. A growing body of evidence suggests that restoration of the dysbiotic gut microbiota and polyamine synthesis is effective in ameliorating metabolic syndrome and strengthening the impaired immune responses of obesity/T2D. In this review, we discuss existing studies on gut microbiome determinants of polyamine synthesis, polyamine production in obesity/T2D, and evidence that demonstrates the potential of polyamines as a nutraceutical in obesity/T2D hosts.

Guanidino acid hydrolysis by the human enzyme annotated as agmatinase

Guanidino acids such as taurocyamine, guanidinobutyrate, guanidinopropionate, and guanidinoacetate have been detected in humans. However, except for guanidionacetate, which is a precursor of creatine, their metabolism and potential functions remain poorly understood. Agmatine has received considerable attention as a potential neurotransmitter and the human enzyme so far annotated as agmatinase (AGMAT) has been proposed as an important modulator of agmatine levels. However, conclusive evidence for the assigned enzymatic activity is lacking. Here we show that AGMAT hydrolyzed a range of linear guanidino acids but was virtually inactive with agmatine. Structural modelling and direct biochemical assays indicated that two naturally occurring variants differ in their substrate preferences. A negatively charged group in the substrate at the end opposing the guanidine moiety was essential for efficient catalysis, explaining why agmatine was not hydrolyzed. We suggest to rename AGMAT as guanidino acid hydrolase (GDAH). Additionally, we demonstrate that the GDAH substrates taurocyamine, guanidinobutyrate and guanidinopropionate were produced by human glycine amidinotransferase (GATM). The presented findings show for the first time an enzymatic activity for GDAH/AGMAT. Since agmatine has frequently been proposed as an endogenous neurotransmitter, the current findings clarify important aspects of the metabolism of agmatine and guanidino acid derivatives in humans.

One-Carbon and Polyamine Metabolism as Cancer Therapy Targets

Cancer metabolic reprogramming is essential for maintaining cancer cell survival and rapid replication. A common target of this metabolic reprogramming is one-carbon metabolism which is notable for its function in DNA synthesis, protein and DNA methylation, and antioxidant production. Polyamines are a key output of one-carbon metabolism with widespread effects on gene expression and signaling. As a result of these functions, one-carbon and polyamine metabolism have recently drawn a lot of interest for their part in cancer malignancy. Therapeutic inhibitors that target one-carbon and polyamine metabolism have thus been trialed as anticancer medications. The significance and future possibilities of one-carbon and polyamine metabolism as a target in cancer therapy are discussed in this review.

Research Progress and Potential Applications of Spermidine in Ocular Diseases

Spermidine, a natural polyamine, exists in almost all human tissues, exhibiting broad properties like anti-aging, autophagy induction, anti-inflammation, anti-oxidation, cell proliferation activation, and ion channel regulation. Considering that spermidine is already present in human nutrition, recent studies targeting supplementing exogenous sources of this polyamine appear feasible. The protective role of spermidine in various systems has been illuminated in the literature, while recent progress of spermidine administration in ocular diseases remains to be clarified. This study shows the current landscape of studies on spermidine and its potential to become a promising therapeutic agent to treat ocular diseases: glaucoma, optic nerve injury, age-related macular degeneration (AMD), cataracts, dry eye syndrome, and bacterial keratitis. It also has the potential to become a potent biomarker to predict keratoconus (KC), cataracts, uveitis, glaucoma, proliferative diabetic retinopathy (PDR), proliferative vitreoretinopathy (PVR), and retinopathy of prematurity (ROP). We also summarize the routes of administration and the effects of spermidine at different doses.

Recent advances on discovery of enzyme inhibitors from natural products using bioactivity screening

The essence of enzymes is to keep the homeostasis and balance of human by catalyzing metabolic responses and modulating cell. Suppression of enzyme slows the progress of some diseases, making it a therapeutic target. Therefore, it is important to develop enzyme inhibitors by proper bioactivity screening strategies for the future treatment of some major diseases. In this review, we summarized the recent (2015-2020) applications of several screening strategies (electrophoretically mediated microanalysis, enzyme immobilization, affinity chromatography, and affinity ultrafiltration) in finding enzyme inhibitors from certain species of bioactive natural compounds of plant origin (flavonoids, alkaloids, phenolic acids, saponins, anthraquinones, coumarins). At the same time, the advantages and disadvantages of each strategy were also discussed, and the future possible development direction in enzyme inhibitor screening has prospected. To sum up, it is expected to help readers select suitable screening strategies for enzyme inhibitors and provide useful information for the study of the biological of specific kinds of natural products. This article is protected by copyright. All rights reserved.

Hyperglycemic conditions proliferate triple negative breast cancer cells: role of ornithine decarboxylase

PURPOSE

Several cancer subtypes (pancreatic, breast, liver, and colorectal) rapidly advance to higher aggressive stages in diabetes. Though hyperglycemia has been considered as a fuel for growth of cancer cells, pathways leading to this condition are still under investigation. Cellular polyamines can modulate normal and cancer cell growth, and inhibitors of polyamine synthesis have been approved for treating colon cancer, however the role of polyamines in diabetes-mediated cancer advancement is unclear as yet. We hypothesized that polyamine metabolic pathway is involved with increased proliferation of breast cancer cells under high glucose (HG) conditions.

METHODS

Studies were performed with varying concentrations of glucose (5-25 mM) exposure in invasive, triple negative breast cancer cells, MDA-MB-231; non-invasive, estrogen/progesterone receptor positive breast cancer cells, MCF-7; and non-tumorigenic mammary epithelial cells, MCF-10A.

RESULTS

There was a significant increase in proliferation with HG (25 mM) at 48-72 h in both MDA-MB-231 and MCF-10A cells but no such effect was observed in MCF-7 cells. This was correlated to higher activity of ornithine decarboxylase (ODC), a rate-limiting enzyme in polyamine synthesis pathway. Inhibitor of polyamine synthesis (difluoromethylornithine, DFMO, 5 mM) was quite effective in suppressing HG-mediated cell proliferation and ODC activity in MDA-MB-231 and MCF-10A cells. Polyamine (putrescine) levels were significantly elevated with HG treatment in MDA-MB-231 cells. HG exposure also increased the metastasis of MDA-MB-231 cells.

CONCLUSIONS

Our cellular findings indicate that polyamine inhibition should be explored in patient population as a target for future chemotherapeutics in diabetic breast cancer.

Metabolism and function of polyamines in cancer progression

Polyamines are essential for the proliferation, differentiation, and development of eukaryotes. They include spermine, spermidine, and the diamine precursor putrescine, and are low-molecular-weight, organic polycations with more than two amino groups. Their intracellular concentrations are strictly maintained within a specific physiological range through several regulatory mechanisms in normal cells. In contrast, polyamine metabolism is dysregulated in many neoplastic states, including cancer. In various types of cancer, polyamine levels are elevated, and crosstalk occurs between polyamine metabolism and oncogenic pathways, such as mTOR and RAS pathways. Thus, polyamines might have potential as therapeutic targets in the prevention and treatment of cancer. The molecular mechanisms linking polyamine metabolism to carcinogenesis must be unraveled to develop novel inhibitors of polyamine metabolism. This overview describes the nature of polyamines, their association with carcinogenesis, the development of polyamine inhibitors and their potential, and the findings of clinical trials.

Polyamine Homeostasis in Development and Disease

Polycationic polyamines are present in nearly all living organisms and are essential for mammalian cell growth and survival, and for development. These positively charged molecules are involved in a variety of essential biological processes, yet their underlying mechanisms of action are not fully understood. Several studies have shown both beneficial and detrimental effects of polyamines on human health. In cancer, polyamine metabolism is frequently dysregulated, and elevated polyamines have been shown to promote tumor growth and progression, suggesting that targeting polyamines is an attractive strategy for therapeutic intervention. In contrast, polyamines have also been shown to play critical roles in lifespan, cardiac health and in the development and function of the brain. Accordingly, a detailed understanding of mechanisms that control polyamine homeostasis in human health and disease is needed to develop safe and effective strategies for polyamine-targeted therapy.

Effects of agmatine, glutamate, arginine, and nitric oxide on executive functions in children with attention deficit hyperactivity disorder

In this study, we aimed to investigate the effects of agmatine, nitric oxide (NO), arginine, and glutamate, which are the metabolites in the polyamine pathway,  on the performance of executive functions (EF) in attention deficit hyperactivity disorder (ADHD). The ADHD group included 35 treatment-naive children (6-14 years old) who were ewly diagnosed with ADHD. The control group consisted of 35 healthy children with the same age and sex, having no previous psychiatric disorders. In the study groups, Stroop test (ST) and trail making test (TMT) were used to monitor EF, and blood samples were collected to measure agmatine with ultra-high-performance liquid chromatography and NO, glutamate, and arginine with enzyme-linked immunosorbent assay (ELISA). The EFs were significantly impaired in the ADHD group. The agmatine and arginine levels of the ADHD group were significantly higher than their peers. The NO and glutamate levels were also higher in the ADHD group compared to the control group, but these differences did not reach statistical significance. Children with ADHD had more difficulties during EF tasks compared to healthy children. The elevated NO and glutamate levels may be related with the impairment during EF tasks. Therefore, agmatine and arginine may increase to improve EF tasks through its inhibitory effect on the synthesis of NO and glutamate. Further studies are needed about polyamine pathway molecules to shed light on the pathophysiology of ADHD.

Agmatinase promotes the lung adenocarcinoma tumorigenesis by activating the NO-MAPKs-PI3K/Akt pathway

Lung adenocarcinoma (LUAD) is one of the leading causes of cancer-related death worldwide. There is an urgent need to uncover the pathogenic mechanism to develop new treatments. Agmatinase (AGMAT) expression and its association with clinicopathological characteristics were analyzed via GEO, Oncomine, and TCGA databases, and IHC staining in human LUAD specimens. An EdU cell proliferation kit, propidiumiodide staining, colony formation, cell migration, and invasion assays, and a xenograft tumor model were used to detect the biological function of AGMAT in LUAD. Furthermore, the expression level of nitric oxide (NO) was detected using a DAF-FMDA fluorescent probe or nitrite assay kit, and further validated with Carboxy-PTIO (a NO scavenger). The roles of three isoforms of nitric oxide synthases (nNOS, eNOS, and iNOS) were validated using L-NAME (eNOS inhibitor), SMT (iNOS inhibitor), and spermidine (nNOS inhibitor). AGMAT expression was up-regulated in LUAD tissues. LUAD patients with high AGMAT levels were associated with poorer prognoses. AGMAT promoted LUAD tumorigenesis in NO released by iNOS both in vitro and in vivo. Importantly, NO signaling up-regulated the expression of cyclin D1 via activating the MAPK and PI3K/Akt-dependent c-myc activity, ultimately promoting the malignant proliferation of tumor cells. On the whole, AGMAT promoted NO release via up-regulating the expression of iNOS. High levels of NO drove LUAD tumorigenesis via activating MAPK and PI3K/Akt cascades. AGMAT might be a potential diagnostic and therapeutic target for LUAD patients.