Oil for the cancer engine: The cross-talk between oncogenic signaling and polyamine metabolism

Impaired polyamine metabolism causes behavioral and neuroanatomical defects in a mouse model of Snyder-Robinson syndrome

Snyder-Robinson syndrome (SRS) is a rare X-linked recessive disorder caused by a mutation in the SMS gene, which encodes spermine synthase, and aberrant polyamine metabolism. SRS is characterized by intellectual disability, thin habitus, seizure, low muscle tone/hypotonia and osteoporosis. Progress towards understanding and treating SRS requires a model that recapitulates human gene variants and disease presentations. Here, we evaluated molecular and neurological presentations in the G56S mouse model, which carries a missense mutation in the Sms gene. The lack of SMS protein in the G56S mice resulted in increased spermidine/spermine ratio, failure to thrive, short stature and reduced bone density. They showed impaired learning capacity, increased anxiety, reduced mobility and heightened fear responses, accompanied by reduced total and regional brain volumes. Furthermore, impaired mitochondrial oxidative phosphorylation was evident in G56S cerebral cortex, G56S fibroblasts and Sms-null hippocampal cells, indicating that SMS may serve as a future therapeutic target. Collectively, our study establishes the suitability of the G56S mice as a preclinical model for SRS and provides a set of molecular and functional outcome measures that can be used to evaluate therapeutic interventions for SRS.

Activation of polyamine catabolism promotes glutamine metabolism and creates a targetable vulnerability in lung cancer

Polyamines are a class of small polycationic alkylamines that play essential roles in both normal and cancer cell growth. Polyamine metabolism is frequently dysregulated and considered a therapeutic target in cancer. However, targeting polyamine metabolism as monotherapy often exhibits limited efficacy, and the underlying mechanisms are incompletely understood. Here we report that activation of polyamine catabolism promotes glutamine metabolism, leading to a targetable vulnerability in lung cancer. Genetic and pharmacological activation of spermidine/spermine N1-acetyltransferase 1 (SAT1), the rate-limiting enzyme of polyamine catabolism, enhances the conversion of glutamine to glutamate and subsequent glutathione (GSH) synthesis. This metabolic rewiring ameliorates oxidative stress to support lung cancer cell proliferation and survival. Simultaneous glutamine limitation and SAT1 activation result in ROS accumulation, growth inhibition, and cell death. Importantly, pharmacological inhibition of either one of glutamine transport, glutaminase, or GSH biosynthesis in combination with activation of polyamine catabolism synergistically suppresses lung cancer cell growth and xenograft tumor formation. Together, this study unveils a previously unappreciated functional interconnection between polyamine catabolism and glutamine metabolism and establishes cotargeting strategies as potential therapeutics in lung cancer.

Natural Product Quercetin-3-methyl ether Promotes Colorectal Cancer Cell Apoptosis by Downregulating Intracellular Polyamine Signaling

Dysregulation of cellular metabolism is a key marker of cancer, and it is suggested that metabolism should be considered as a targeted weakness of colorectal cancer. Increased polyamine metabolism is a common metabolic change in tumors. Thus, targeting polyamine metabolism for anticancer therapy, particularly polyamine blockade therapy, has gradually become a hot topic. Quercetin-3-methyl ether is a natural compound existed in various plants with diverse biological activities like antioxidant and antiaging. Here, we reported that Quercetin-3-methyl ether inhibits colorectal cancer cell viability, and promotes apoptosis in a dose-dependent and time-dependent manner. Intriguingly, the polyamine levels, including spermidine and spermine, in colorectal cancer cells were reduced upon treatment of Quercetin-3-methyl ether. This is likely resulted from the downregulation of SMOX, a key enzyme in polyamine metabolism that catalyzes the oxidation of spermine to spermidine. These findings suggest Quercetin-3-methyl ether decreases cellular polyamine level by suppressing SMOX expression, thereby inducing colorectal cancer cell apoptosis. Our results also reveal a correlation between the anti-tumor activity of Quercetin-3-methyl ether and the polyamine metabolism modulation, which may provide new insights into a better understanding of the pharmacological activity of Quercetin-3-methyl ether and how it reprograms cellular polyamine metabolism.

Role of m6A modification in regulating the PI3K/AKT signaling pathway in cancer

The phosphoinositide 3-kinase (PI3K)/AKT signaling pathway plays a crucial role in the pathogenesis of cancer. The dysregulation of this pathway has been linked to the development and initiation of various types of cancer. Recently, epigenetic modifications, particularly N6-methyladenosine (m6A), have been recognized as essential contributors to mRNA-related biological processes and translation. The abnormal expression of m6A modification enzymes has been associated with oncogenesis, tumor progression, and drug resistance. Here, we review the role of m6A modification in regulating the PI3K/AKT pathway in cancer and its implications in the development of novel strategies for cancer treatment.

Molecular Subtypes and Machine Learning-Based Predictive Models for Intracranial Aneurysm Rupture

BACKGROUND

The determination of biological mechanisms and biomarkers related to intracranial aneurysm (IA) rupture is of utmost significance for the development of effective preventive and therapeutic strategies in the clinical field.

METHODS

GSE122897 and GSE13353 datasets were downloaded from Gene Expression Omnibus. Data extracted from GSE122897 were used for analyzing differential gene expression, and consensus clustering was performed to identify stable molecular subtypes. Clinical characteristics were compared between subgroups, and fast gene set enrichment analysis and weighted gene coexpression network analysis were performed. Hub genes were identified via least absolute shrinkage and selection operator analysis. Predictive models were constructed based on hub genes using the Light Gradient Boosting Machine, eXtreme Gradient Boosting, and logistic regression algorithm. Immune cell infiltration in IA samples was analyzed using Microenvironment Cell Population counter, CIBERSORT, and xCell algorithm. The correlation between hub genes and immune cells was analyzed. The predictive model and immune cell infiltration were validated using data from the GSE13353 dataset.

RESULTS

A total of 43 IA samples were classified into 2 subgroups based on gene expression profiles. Subgroup I had a higher risk of rupture, while 70% of subgroup II remained unruptured. In subgroup I, specific genes were associated with inflammation and immunity, and weighted gene coexpression network analysis revealed that the black module genes were linked to IA rupture. We identified 4 hub genes (spermine synthase, macrophage receptor with collagenous structure, zymogen granule protein 16B, and LIM and calponin-homology domains 1), which constructed predictive models with good diagnostic performance in differentiating between ruptured and unruptured IA samples. Monocytic lineage was found to be a significant factor in IA rupture, and the 4 hub genes were linked to monocytic lineage (P < 0.05).

CONCLUSIONS

We reveal a new molecular subtype that can reflect the actual pathological state of IA rupture, and our predictive models constructed by machine learning algorithms can efficiently predict IA rupture.

Polyamine catabolism is concentrated in tumor-associated histiocytes in diffuse large B-cell lymphoma and classic Hodgkin lymphoma

Polyamines are cationic molecules necessary for cell survival, growth, and replication [1-5]. Polyamines come in a variety of structural forms and are principally regulated by two enzymes, spermine/spermidine acetyltransferase-1 (SAT1) and ornithine decarboxylase-1 (ODC1). SAT1 targets the polyamines spermidine and spermine for degradation via acetylation, while ODC1 is involved in converting the polyamine precursor molecule to more complex polyamines [6-8]. Polyamines and their regulatory enzymes have been implicated in tumor metastasis [9,10] and in crosstalk between oncogenes [11-13] in numerous types of cancer, but their role has never been evaluated in B-cell malignancies. In this study, we examine the expression of SAT1 in diffuse large B-cell lymphoma (DLBCL) and classic Hodgkin lymphoma (HL). We found that SAT1 is expressed in all examined cases of DLBCL (n = 15) and HL (n = 5), though the levels of expression across cases vary. We also note that SAT1 expression appears to be concentrated in tumor-associated histiocytes, rather than tumor cells in both DLBCL and HL. We propose that these findings indicate that the polyamine catabolic enzyme, SAT1, plays an unappreciated role in the pathogenesis of B-cell neoplasms.

Maternal-fetal toxicity of Strychnos pseudoquina extract treatment during pregnancy

ETHNOPHARMACOLOGICAL RELEVANCE

Plants and herbs have been used by women throughout history for therapeutic purposes. Strychnos pseudoquina, a plant used in the treatment of various diseases, can also function as an abortive herb. There is no scientific confirmation of its effects during pregnancy, and the activity of this plant needs to be substantiated or refuted with experimental evidence.

AIM OF THE STUDY

Evaluating the effect of the S. pseudoquina aqueous extract on maternal reproductive toxicity and fetal development.

MATERIALS AND METHODS

The aqueous extract of S. pseudoquina bark was evaluated in Wistar rats. Pregnant rats were distributed into four experimental groups (n = 12 rats/group): Control = treated with water (vehicle); Treated 75, Treated 150, and Treated 300 = treated with S. pseudoquina at dose 75, 150 and 300 mg/kg, respectively. The rats were treated by an intragastric route (gavage) from day 0 to day 21 of pregnancy. At the end of pregnancy, maternal reproductive outcomes, organs, biochemical and hematological profiles, fetuses, and placentas were analyzed. Maternal toxicity was evaluated through body weight gain, water, and food intake. With knowledge of the harmful dosage of the plant, other rats were used on gestational day 4 for the evaluation of morphological analyses before embryo implantation. P < 0.05 was considered as statistically significant.

RESULTS

The S. pseudoquina treatment showed elevated liver enzymatic activities. The Treated 300 group presented toxicity with reduced maternal body weight, water and food intake, and increased kidney relative weight compared to those of the Control group. At a high dosage, the plant presents an abortifacient activity, confirmed by embryo losses before and after implantation and degenerated blastocysts. In addition, the treatment contributed to an increased percentage of fetal visceral anomalies, decreased ossification sites, and intrauterine growth restriction (300 mg/kg dose).

CONCLUSION

In general, our study showed that an aqueous extract of S. pseudoquina bark caused significant abortifacient activity that testified to its traditional use. Furthermore, the S. pseudoquina extract caused maternal toxicity that contributed to impaired embryofetal development. Therefore, the use of this plant should be completely avoided during pregnancy to prevent unintended abortion and risks to maternal-fetal health.

Tumor cell-derived spermidine is an oncometabolite that suppresses TCR clustering for intratumoral CD8+ T cell activation

The activation and expansion of T cells that recognize cancer cells is an essential aspect to antitumor immunity. Tumors may escape destruction by the immune system through ectopic expression of inhibitory immune ligands typically exemplified by the PD-L1/PD-1 pathway. Here, we reveal another facet of tumor evasion from T cell surveillance. By secretome profiling of necrotic tumor cells, we identified an oncometabolite spermidine as a unique inhibitor of T cell receptor (TCR) signaling. Mechanistically, spermidine causes the downregulation of the plasma membrane cholesterol levels, resulting in the suppression of TCR clustering. Using syngeneic mouse models, we show that spermidine is abundantly detected in the tumor immune microenvironment (TIME) and that administration of the polyamine synthesis inhibitor effectively enhanced CD8+ T cell-dependent antitumor responses. Further, the combination of the polyamine synthesis inhibitor with anti-PD-1 immune checkpoint antibody resulted in a much stronger antitumor immune response. This study reveals an aspect of immunosuppressive TIME, wherein spermidine functions as a metabolic T cell checkpoint that may offer a unique approach for promoting tumor immunotherapy.

Fibronectin, DHPS and SLC3A2 Signaling Cooperate to Control Tumor Spheroid Growth, Subcellular eIF5A1/2 Distribution and CDK4/6 Inhibitor Resistance

Extracellular matrix (ECM) protein expression/deposition within and stiffening of the breast cancer microenvironment facilitates disease progression and correlates with poor patient survival. However, the mechanisms by which ECM components control tumorigenic behaviors and responses to therapeutic intervention remain poorly understood. Fibronectin (FN) is a major ECM protein controlling multiple processes. In this regard, we previously reported that DHPS-dependent hypusination of eIF5A1/2 is necessary for fibronectin-mediated breast cancer metastasis and epithelial to mesenchymal transition (EMT). Here, we explored the clinical significance of an interactome generated using hypusination pathway components and markers of intratumoral heterogeneity. Solute carrier 3A2 (SLC3A2 or CD98hc) stood out as an indicator of poor overall survival among patients with basal-like breast cancers that express elevated levels of DHPS. We subsequently discovered that blockade of DHPS or SLC3A2 reduced triple negative breast cancer (TNBC) spheroid growth. Interestingly, spheroids stimulated with exogenous fibronectin were less sensitive to inhibition of either DHPS or SLC3A2 - an effect that could be abrogated by dual DHPS/SLC3A2 blockade. We further discovered that a subset of TNBC cells responded to fibronectin by increasing cytoplasmic localization of eIF5A1/2. Notably, these fibronectin-induced subcellular localization phenotypes correlated with a G0/G1 cell cycle arrest. Fibronectin-treated TNBC cells responded to dual DHPS/SLC3A2 blockade by shifting eIF5A1/2 localization back to a nucleus-dominant state, suppressing proliferation and further arresting cells in the G2/M phase of the cell cycle. Finally, we observed that dual DHPS/SLC3A2 inhibition increased the sensitivity of both Rb-negative and -positive TNBC cells to the CDK4/6 inhibitor palbociclib. Taken together, these data identify a previously unrecognized mechanism through which extracellular fibronectin controls cancer cell tumorigenicity by modulating subcellular eIF5A1/2 localization and provides prognostic/therapeutic utility for targeting the cooperative DHPS/SLC3A2 signaling axis to improve breast cancer treatment responses.

Effectiveness of a novel gene nanotherapy based on putrescine for cancer treatment

Gene therapy has long been proposed for cancer treatment. However, the use of therapeutic nucleic acids presents several limitations such as enzymatic degradation, rapid clearance, and poor cellular uptake and efficiency. In this work we propose the use of putrescine, a precursor for higher polyamine biosynthesis for the preparation of cationic nanosystems for cancer gene therapy. We have formulated and characterized putrescine-sphingomyelin nanosystems (PSN) and studied their endocytic pathway and intracellular trafficking in cancer cells. After loading a plasmid DNA (pDNA) encoding the apoptotic Fas Ligand (FasL), we proved their therapeutic activity by measuring the cell death rate after treatment of MDA-MB-231 cells. We have also used xenografted zebrafish embryos as a first in vivo approach to demonstrate the efficacy of the proposed PSN-pDNA formulation in a more complex model. Finally, intratumoral and intraperitoneal administration to mice-bearing MDA-MB-231 xenografts resulted in a significant decrease in tumour cell growth, highlighting the potential of the developed gene therapy nanoformulation for the treatment of triple negative breast cancer.

Impaired polyamine metabolism causes behavioral and neuroanatomical defects in a novel mouse model of Snyder-Robinson Syndrome

Polyamines (putrescine, spermidine, and spermine) are essential molecules for normal cellular functions and are subject to strict metabolic regulation. Mutations in the gene encoding spermine synthase (SMS) lead to accumulation of spermidine in an X-linked recessive disorder known as Snyder-Robinson syndrome (SRS). Presently, no treatments exist for this rare disease that manifests with a spectrum of symptoms including intellectual disability, developmental delay, thin habitus, and low muscle tone. The development of therapeutic interventions for SRS will require a suitable disease-specific animal model that recapitulates many of the abnormalities observed in patients. Here, we characterize the molecular, behavioral, and neuroanatomical features of a mouse model with a missense mutation in Sms gene that results in a glycine-to-serine substitution at position 56 (G56S) of the SMS protein. Mice harboring this mutation exhibit a complete loss of SMS protein and elevated spermidine/spermine ratio in skeletal muscles and the brain. In addition, the G56S mice demonstrate increased anxiety, impaired learning, and decreased explorative behavior in fear conditioning, Morris water maze, and open field tests, respectively. Furthermore, these mice failed to gain weight over time and exhibit abnormalities in brain structure and bone density. Transcriptomic analysis of the cerebral cortex revealed downregulation of genes associated with mitochondrial oxidative phosphorylation and ribosomal protein synthesis. Our findings also revealed impaired mitochondrial bioenergetics in fibroblasts isolated from the G56S mice, indicating a correlation between these processes in the affected mice. Collectively, our findings establish the first in-depth characterization of an SRS preclinical mouse model that identifies cellular processes that could be targeted for future therapeutic development.

Spermine oxidase induces DNA damage and sensitizes fusion negative rhabdomyosarcoma cells to irradiation

Rhabdomyosarcoma (RMS) is a pediatric myogenic soft tissue sarcoma that includes fusion-positive (FP) and fusion-negative (FN) molecular subtypes. FP-RMS expresses PAX3-FOXO1 fusion protein and often shows dismal prognosis. FN-RMS shows cytogenetic abnormalities and frequently harbors RAS pathway mutations. Despite the multimodal heavy chemo and radiation therapeutic regimens, high risk metastatic/recurrent FN-RMS shows a 5-year survival less than 30% due to poor sensitivity to chemo-radiotherapy. Therefore, the identification of novel targets is needed. Polyamines (PAs) such as putrescine (PUT), spermidine (SPD) and spermine (SPM) are low-molecular-mass highly charged molecules whose intracellular levels are strictly modulated by specific enzymes. Among the latter, spermine oxidase (SMOX) regulates polyamine catabolism oxidizing SPM to SPD, which impacts cellular processes such as apoptosis and DNA damage response. Here we report that low SMOX levels are associated with a worse outcome in FN-RMS, but not in FP-RMS, patients. Consistently, SMOX expression is downregulated in FN-RMS cell lines as compared to normal myoblasts. Moreover, SMOX transcript levels are reduced FN-RMS cells differentiation, being indirectly downregulated by the muscle transcription factor MYOD. Noteworthy, forced expression of SMOX in two cell lines derived from high-risk FN-RMS: 1) reduces SPM and upregulates SPD levels; 2) induces G0/G1 cell cycle arrest followed by apoptosis; 3) impairs anchorage-independent and tumor spheroids growth; 4) inhibits cell migration; 5) increases γH2AX levels and foci formation indicative of DNA damage. In addition, forced expression of SMOX and irradiation synergize at activating ATM and DNA-PKCs, and at inducing γH2AX expression and foci formation, which suggests an enhancement in DNA damage response. Irradiated SMOX-overexpressing FN-RMS cells also show significant decrease in both colony formation capacity and spheroids growth with respect to single approaches. Thus, our results unveil a role for SMOX as inhibitor of tumorigenicity of FN-RMS cells in vitro. In conclusion, our in vitro results suggest that SMOX induction could be a potential combinatorial approach to sensitize FN-RMS to ionizing radiation and deserve further in-depth studies.

miR‑151a‑5p promotes the proliferation and metastasis of colorectal carcinoma cells by targeting AGMAT

Colorectal carcinoma (CRC) is one of the most common types of digestive cancer. It has been reported that the ectopic expression of microRNAs (miRs) plays a critical role in the occurrence and progression of CRC. In addition, it has also been suggested that miR‑151a‑5p may serve as a useful biomarker for the early detection and treatment of different types of cancer and particularly CRC. However, the specific effects and underlying mechanisms of miR‑151a‑5p in CRC remain elusive. The results of the current study demonstrated that miR‑151a‑5p was upregulated in CRC cell lines and clinical tissues derived from patients with CRC. Functionally, the results showed that miR‑151a‑5p significantly promoted CRC cell proliferation, migration and invasion. Additionally, dual luciferase reporter assays verified that agmatinase (AGMAT) was a direct target of miR‑151a‑5p and it was positively associated with miR‑151a‑5p expression. Mechanistically, miR‑151a‑5p could enhance the epithelial‑mesenchymal transition of CRC cells. Taken together, the results of the current study revealed a novel molecular mechanism indicating that the miR‑151a‑5p/AGMAT axis could serve a crucial role in the regulation of CRC and could therefore be considered as a potential therapeutic strategy for CRC.

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.

MicroRNA-378a-3p prevents initiation and growth of colorectal cancer by fine tuning polyamine synthesis

BACKGROUND

Inhibitors of ornithine decarboxylase (ODC) are effective at preventing colorectal cancer (CRC). However, their high toxicity limits their clinical application. This study was aimed to explore the potential of microRNAs (miRNAs) as an inhibitor of ODC.

METHODS

miRNA array was used to identify dysregulated miRNAs in CRC tumors of mice and patients. Azoxymethane (AOM)/Dextran Sodium Sulfate (DSS) were used to induce CRC in mice. miRNA function in carcinogenesis was determined by soft-agar colony formation, flow cytometry, and wound healing of CRC cells. Mini-circle was used to deliver miRNA into colons.

RESULTS

MiRNA profiling identified miR-378a-3p (miR-378a) as the most reduced miRNA in CRC tumors of patients and mice treated with AOM/DSS. Pathway array analysis revealed that miR-378a impaired c-MYC and ODC1 pathways. Further studies identified FOXQ1 (forkhead box Q1) and ODC1 as two direct targets of miR-378a. FOXQ1 activated transcription of c-MYC, a transcription activator of ODC1. In addition to directly targeting ODC1, miR-378a also inhibited expression of ODC1 via the FOXQ1-cMYC axis, thereby inhibiting polyamine synthesis in human CRC cells. Phenotypically, by reducing polyamine synthesis, miR-378a induced apoptosis and inhibited proliferation and migration of CRC cells, while disrupting the association of miR-378a with FOXQ1 and ODC1 offset the effects of miR-378a, suggesting that FOXQ1 and ODC1 were required for miR-378a to inhibit CRC cell growth. MiR-378a treatment robustly prevented growth of HCC by inhibiting polyamine synthesis in AOM/DSS mice.

CONCLUSION

MiR-378a prevents CRC by inhibiting polyamine synthesis, suggesting its use as a novel ODC inhibitor against CRC.

CD8+ T cell metabolic rewiring defined by scRNA-seq identifies a critical role of ASNS expression dynamics in T cell differentiation

T cells dynamically rewire their metabolism during an immune response. We applied single-cell RNA sequencing to CD8⁺ T cells activated and differentiated in vitro in physiological medium to resolve these metabolic dynamics. We identify a differential time-dependent reliance of activating T cells on the synthesis versus uptake of various non-essential amino acids, which we corroborate with functional assays. We also identify metabolic genes that potentially dictate the outcome of T cell differentiation, by ranking them based on their expression dynamics. Among them, we find asparagine synthetase (Asns), whose expression peaks for effector T cells and decays toward memory formation. Disrupting these expression dynamics by ASNS overexpression promotes an effector phenotype, enhancing the anti-tumor response of adoptively transferred CD8⁺ T cells in a mouse melanoma model. We thus provide a resource of dynamic expression changes during CD8⁺ T cell activation and differentiation, and identify ASNS expression dynamics as a modulator of CD8⁺ T cell differentiation.

METTL3-IGF2BP3-axis mediates the proliferation and migration of pancreatic cancer by regulating spermine synthase m6A modification

Spermine synthase (SMS) is an enzyme participating in polyamine synthesis; however, its function and role in pancreatic cancer remains elusive. Here we report that SMS is upregulated in pancreatic cancer and predicts a worse overall survival and significantly promotes the proliferation and migration of pancreatic cancer cells. Excessive SMS reduces the accumulation of spermidine by converting spermidine into spermine, which activates the phosphorylation of serine/threonine kinase (AKT) and epithelial-mesenchymal transition (EMT) signaling pathway, thereby inhibiting pancreatic cancer cell proliferation and invasion. Moreover, SMS was identified as the direct target of both methyltransferase like 3 (METTL3) and insulin like growth factor 2 mRNA binding protein 3 (IGF2BP3), which directly bind to the m6A modification sites of SMS and inhibit mRNA degradation. Knockdown of METTL3 or IGF2BP3 significantly reduced the SMS protein expression and inhibited the migration of pancreatic cancer. We propose a novel regulatory mechanism in which the METTL3-IGF2BP3 axis mediates the mRNA degradation of SMS in an m6A-dependent manner to regulate spermine/spermidine conversion, which regulates AKT phosphorylation and EMT activation, thereby inducing tumor progression and migration in pancreatic cancer.

Autophagy-inducing nutritional interventions in experimental and clinical oncology

Numerous pro-autophagic dietary interventions are being investigated for their potential cancer-preventive or therapeutic effects. This applies to different fasting regimens, methionine restriction and ketogenic diets. In addition, the supplementation of specific micronutrients such as nicotinamide (vitamin B3) or spermidine induces autophagy. In humans, leanness, plant-based diets (that may lead to partial methionine restriction) and high dietary uptake of spermidine are associated with a low incidence of cancers. Moreover, clinical trials have demonstrated the capacity of nicotinamide to prevent non-melanoma skin carcinogenesis. Multiple interventional trials are evaluating the capacity of autophagy-inducing regimens to improve the outcome of chemotherapy and immunotherapy. Here, we discuss the mechanistic underpinnings of autophagy induction by nutritional interventions, as well as the mechanisms through which autophagy induction in malignant or immune cells improves anticancer immunosurveillance.

Understanding the Polyamine and mTOR Pathway Interaction in Breast Cancer Cell Growth

The polyamines putrescine, spermidine and spermine are nutrient-like polycationic molecules involved in metabolic processes and signaling pathways linked to cell growth and cancer. One important pathway is the PI3K/Akt pathway where studies have shown that polyamines mediate downstream growth effects. Downstream of PI3K/Akt is the mTOR signaling pathway, a nutrient-sensing pathway that regulate translation initiation through 4EBP1 and p70S6K phosphorylation and, along with the PI3K/Akt, is frequently dysregulated in breast cancer. In this study, we investigated the effect of intracellular polyamine modulation on mTORC1 downstream protein and general translation state in two breast cancer cell lines, MCF-7 and MDA-MB-231. The effect of mTORC1 pathway inhibition on the growth and intracellular polyamines was also measured. Results showed that polyamine modulation alters 4EBP1 and p70S6K phosphorylation and translation initiation in the breast cancer cells. mTOR siRNA gene knockdown also inhibited cell growth and decreased putrescine and spermidine content. Co-treatment of inhibitors of polyamine biosynthesis and mTORC1 pathway induced greater cytotoxicity and translation inhibition in the breast cancer cells. Taken together, these data suggest that polyamines promote cell growth in part through interaction with mTOR pathway. Similarly intracellular polyamine content appears to be linked to mTOR pathway regulation. Finally, dual inhibition of polyamine and mTOR pathways may provide therapeutic benefits in some breast cancers.

Approaching to biogenic amines as quality markers in packaged chicken meat

Following the chicken meat quality decay remains a tricky procedure. On one hand, food companies need of fast and affordable methods to keep constant higher sensory and safety standards, on the other hand, food scientists and operators find difficult conjugating these exigencies by means of univocal parameters. Food quality definition itself is, in fact, a multi-layered and composite concept in which many features play a part. Thus, here we propose an index that relies on biogenic amines (BAs) evolution. These compounds may indirectly inform about microbial contamination and wrong management, production, and storage conditions of meat and meat products. In this study, three cuts of chicken meat (breast filets, drumsticks, and legs) packed under modified atmosphere, under vacuum, and in air-packaging, stored at +4°C (until to 15 days), were analyzed. Some BAs were combined in an index (BAI) and their evolution was followed. The Thiobarbituric Acid Reactive Species assay (TBARS) was also used as a common reference method. Generally, BAI may better identify the beginning of quality impairment than lipid oxidation spreading. ANOVA statistical analysis has highlighted that the storage time is anyway the most detrimental factor for chicken decay when it is stored in refrigerated rooms (p > 0.01). Despite TBARS still remains a powerful tool for chicken goods, its exclusive use may not be enough to explain quality loss. On the contrary, BAI implementation in fresh meat can give a more complete information combining food safety exigencies with sensory attributes.

Structure of human spermine oxidase in complex with a highly selective allosteric inhibitor

Human spermine oxidase (hSMOX) plays a central role in polyamine catabolism. Due to its association with several pathological processes, including inflammation and cancer, hSMOX has garnered interest as a possible therapeutic target. Therefore, determination of the structure of hSMOX is an important step to enable drug discovery and validate hSMOX as a drug target. Using insights from hydrogen/deuterium exchange mass spectrometry (HDX-MS), we engineered a hSMOX construct to obtain the first crystal structure of hSMOX bound to the known polyamine oxidase inhibitor MDL72527 at 2.4 Å resolution. While the overall fold of hSMOX is similar to its homolog, murine N1-acetylpolyamine oxidase (mPAOX), the two structures contain significant differences, notably in their substrate-binding domains and active site pockets. Subsequently, we employed a sensitive biochemical assay to conduct a high-throughput screen that identified a potent and selective hSMOX inhibitor, JNJ-1289. The co-crystal structure of hSMOX with JNJ-1289 was determined at 2.1 Å resolution, revealing that JNJ-1289 binds to an allosteric site, providing JNJ-1289 with a high degree of selectivity towards hSMOX. These results provide crucial insights into understanding the substrate specificity and enzymatic mechanism of hSMOX, and for the design of highly selective inhibitors.

Rational engineering of human spermine oxidase yields crystallizable structures and the design of an allosteric inhibitor.

Polyamines in cancer: integrating organismal metabolism and antitumour immunity

The natural mammalian polyamines putrescine, spermidine and spermine are essential for both normal and neoplastic cell function and replication. Dysregulation of metabolism of polyamines and their requirements is common in many cancers. Both clinical and experimental depletion of polyamines have demonstrated their metabolism to be a rational target for therapy; however, the mechanisms through which polyamines can establish a tumour-permissive microenvironment are only now emerging. Recent data indicate that polyamines can play a major role in regulating the antitumour immune response, thus likely contributing to the existence of immunologically 'cold' tumours that do not respond to immune checkpoint blockade. Additionally, the interplay between the microbiota and associated tissues creates a tumour microenvironment in which polyamine metabolism, content and function can all be dramatically altered on the basis of microbiota composition, dietary polyamine availability and tissue response to its surrounding microenvironment. The goal of this Perspective is to introduce the reader to the many ways in which polyamines, polyamine metabolism, the microbiota and the diet interconnect to establish a tumour microenvironment that facilitates the initiation and progression of cancer. It also details ways in which polyamine metabolism and function can be successfully targeted for therapeutic benefit, including specifically enhancing the antitumour immune response.

Amino acid metabolism: challenges and opportunities for the therapeutic treatment of leukemia and lymphoma

Leukemia and lymphoma-the most common hematological malignant diseases-are often accompanied by complications such as drug resistance, refractory diseases and relapse. Amino acids (AAs) are important energy sources for malignant cells. Tumor-mediated AA metabolism is associated with the immunosuppressive properties of the tumor microenvironment, thereby assisting malignant cells to evade immune surveillance. Targeting abnormal AA metabolism in the tumor microenvironment may be an effective therapeutic approach to address the therapeutic challenges of leukemia and lymphoma. Here, we review the effects of glutamine, arginine and tryptophan metabolism on tumorigenesis and immunomodulation, and define the differences between tumor cells and immune effector cells. We also comment on treatments targeting these AA metabolism pathways in lymphoma and leukemia and discuss how these treatments have profound adverse effects on tumor cells, but leave the immune cells unaffected or mildly affected.

A novel signature derived from metabolism-related genes GPT and SMS to predict prognosis of laryngeal squamous cell carcinoma

Background

A growing body of evidence has suggested the involvement of metabolism in the occurrence and development of tumors. But the link between metabolism and laryngeal squamous cell carcinoma (LSCC) has rarely been reported. This study seeks to understand and explain the role of metabolic biomarkers in predicting the prognosis of LSCC.

Methods

We identified the differentially expressed metabolism-related genes (MRGs) through RNA-seq data of The Cancer Genome Atlas (TCGA) and Gene set enrichment analysis (GSEA). After the screening of protein–protein interaction (PPI), hub MRGs were analyzed by least absolute shrinkage and selection operator (LASSO) and Cox regression analyses to construct a prognostic signature. Kaplan–Meier survival analysis and the receiver operating characteristic (ROC) was applied to verify the effectiveness of the prognostic signature in four cohorts (TCGA cohort, GSE27020 cohort, TCGA-sub1 cohort and TCGA-sub2 cohort). The expressions of the hub MRGs in LSCC cell lines and clinical samples were verified by quantitative reverse transcriptase PCR (qRT-PCR). The immunofluorescence staining of the tissue microarray (TMA) was carried out to further verify the reliability and validity of the prognostic signature. Cox regression analysis was then used to screen for independent prognostic factors of LSCC and a nomogram was constructed based on the results.

Results

Among the 180 differentially expressed MRGs, 14 prognostic MRGs were identified. A prognostic signature based on two MRGs (GPT and SMS) was then constructed and verified via internal and external validation cohorts. Compared to the adjacent normal tissues, SMS expression was higher while GPT expression was lower in LSCC tissues, indicating poorer outcomes. The prognostic signature was proven as an independent risk factor for LSCC in both internal and external validation cohorts. A nomogram based on these results was developed for clinical application.

Conclusions

Differentially expressed MRGs were found and proven to be related to the prognosis of LSCC. We constructed a novel prognostic signature based on MRGs in LSCC for the first time and verified it via different cohorts from both databases and clinical samples. A nomogram based on this prognostic signature was developed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02647-2.

Phenylbutyrate modulates polyamine acetylase and ameliorates Snyder-Robinson syndrome in a Drosophila model and patient cells

Polyamine dysregulation plays key roles in a broad range of human diseases from cancer to neurodegeneration. Snyder-Robinson syndrome (SRS) is the first known genetic disorder of the polyamine pathway, caused by X-linked recessive loss-of-function mutations in spermine synthase. In the Drosophila SRS model, altered spermidine/spermine balance has been associated with increased generation of ROS and aldehydes, consistent with elevated spermidine catabolism. These toxic byproducts cause mitochondrial and lysosomal dysfunction, which are also observed in cells from SRS patients. No efficient therapy is available. We explored the biochemical mechanism and discovered acetyl-CoA reduction and altered protein acetylation as potentially novel pathomechanisms of SRS. We repurposed the FDA-approved drug phenylbutyrate (PBA) to treat SRS using an in vivo Drosophila model and patient fibroblast cell models. PBA treatment significantly restored the function of mitochondria and autolysosomes and extended life span in vivo in the Drosophila SRS model. Treating fibroblasts of patients with SRS with PBA ameliorated autolysosome dysfunction. We further explored the mechanism of drug action and found that PBA downregulates the first and rate-limiting spermidine catabolic enzyme spermidine/spermine N1-acetyltransferase 1 (SAT1), reduces the production of toxic metabolites, and inhibits the reduction of the substrate acetyl-CoA. Taken together, we revealed PBA as a potential modulator of SAT1 and acetyl-CoA levels and propose PBA as a therapy for SRS and potentially other polyamine dysregulation-related diseases.

The biguanide polyamine analog verlindamycin promotes differentiation in neuroblastoma via induction of antizyme

Deregulated polyamine biosynthesis is emerging as a common feature of neuroblastoma and drugs targeting this metabolic pathway such as DFMO are in clinical and preclinical development. The polyamine analog verlindamycin inhibits the polyamine biosynthesis pathway enzymes SMOX and PAOX, as well as the histone demethylase LSD1. Based on our previous research in acute myeloid leukemia (AML), we reasoned verlindamycin may also unblock neuroblastoma differentiation when combined with all-trans-retinoic acid (ATRA). Indeed, co-treatment with verlindamycin and ATRA strongly induced differentiation regardless of MYCN status, but in MYCN-expressing cells, protein levels were strongly diminished. This process was not transcriptionally regulated but was due to increased degradation of MYCN protein, at least in part via ubiquitin-independent, proteasome-dependent destruction. Here we report that verlindamycin effectively induces the expression of functional tumor suppressor-antizyme via ribosomal frameshifting. Consistent with previous results describing the function of antizyme, we found that verlindamycin treatment led to the selective targeting of ornithine decarboxylase (the rate-limiting enzyme for polyamine biosynthesis) as well as key oncoproteins, such as cyclin D and Aurora A kinase. Retinoid-based multimodal differentiation therapy is one of the few interventions that extends relapse-free survival in MYCN-associated high-risk neuroblastoma and these results point toward the potential use of verlindamycin in this regimen.

Nanospermidine in Combination with Nanofenretinide Induces Cell Death in Neuroblastoma Cell Lines

A new strategy to cause cell death in tumors might be the increase of intracellular polyamines at concentrations above their physiological values to trigger the production of oxidation metabolites at levels exceeding cell tolerance. To test this hypothesis, we prepared nanospermidine as a carrier for spermidine penetration into the cells, able to escape the polyamine transport system that strictly regulates intracellular polyamine levels. Nanospermidine was prepared by spermidine encapsulation in nanomicelles and was characterized by size, zeta potential, loading, dimensional stability to dilution, and stability to spermidine leakage. Antitumor activity, ROS production, and cell penetration ability were evaluated in vitro in two neuroblastoma cell lines (NLF and BR6). Nanospermidine was tested as a single agent and in combination with nanofenretinide. Free spermidine was also tested as a comparison. The results indicated that the nanomicelles successfully transported spermidine into the cells inducing cell death in a concentration range (150–200 μM) tenfold lower than that required to provide similar cytotoxicity with free spermidine (1500–2000 μM). Nanofenretinide provided a cytostatic effect in combination with the lowest nanospermidine concentrations evaluated and slightly improved nanospermidine cytotoxicity at the highest concentrations. These data suggest that nanospermidine has the potential to become a new approach in cancer treatment. At the cellular level, in fact, it exploits polyamine catabolism by means of biocompatible doses of spermidine and, in vivo settings, it can exploit the selective accumulation of nanomedicines at the tumor site. Nanofenretinide combination further improves its efficacy. Furthermore, the proven ability of spermidine to activate macrophages and lymphocytes suggests that nanospermidine could inhibit immunosuppression in the tumor environment.

Urea transporter B downregulates polyamines levels in melanoma B16 cells via p53 activation

Urea transporter B (UT-B, encoded by the SLC14A1 gene) is a membrane channel protein involved in urea transmembrane transport. Compared with normal tissues, UT-B expression is significantly decreased in most tumours, especially melanoma. However, the UT-B role in tumorigenesis and development is still unclear. Herein, we investigated the effects of UT-B overexpression on polyamine metabolism and the urea cycle in murine melanoma B16 cells, to explore the roles of mitochondrial dysfunction and p53 activation in cell growth and polyamines metabolism. UT-B overexpression in B16 cells decreased cell growth, increased apoptosis, and significantly altered metabolic pathways related to the urea cycle, which were characterized by reduced production of urea and polyamines and increased production of nitric oxide. Subsequently, we observed that activation of the p53 pathway may be the main cause of the above phenomena. The p53 inhibitor pifithrin-α partially restored the production of polyamines, but the mitochondrial morphology and function were still impaired. Further treatment of UT-B-overexpressing B16 cells with reactive oxygen species scavenging agent N-acetyl-l-cysteine and coenzyme Q10 restored cell viability and mitochondrial function and increased polyamine production. In conclusion, UT-B overexpression caused mitochondrial dysfunction and increased oxidative stress in B16 cells, and then activated p53 expression, which may be one of the mechanisms leading to the decrease in intracellular polyamines.

Downregulation of MTAP promotes Tumor Growth and Metastasis by regulating ODC Activity in Breast Cancer

5'-Methylthioadenosine phosphorylase (MTAP) is a key enzyme in the methionine salvage pathway and has been reported to suppress tumorigenesis. The MTAP gene is located at 9p21, a chromosome region often deleted in breast cancer (BC). However, the clinical and biological significance of MTAP in BC is still unclear. Here, we reported that MTAP was frequently downregulated in 41% (35/85) of primary BCs and 89% (8/9) of BC cell lines. Low expression of MTAP was significantly correlated with a poor survival of BC patients (P=0.0334). Functional studies showed that MTAP was able to suppress both in vitro and in vivo tumorigenic ability of BC cells, including migration, invasion, angiogenesis, tumor growth and metastasis in nude mice with orthotopic xenograft tumor of BC. Mechanistically, we found that downregulation of MTAP could increase the polyamine levels by activating ornithine decarboxylase (ODC). By treating the MTAP-repressing BC cells with specific ODC inhibitor Difluoromethylornithine (DFMO) or treating the MTAP-overexpressing BC cells with additional putrescine, metastasis-promoting or -suppressing phenotype of these MTAP-manipulated cells was significantly reversed, respectively. Taken together, our data suggested that MTAP has a critical metastasis-suppressive role by tightly regulating ODC activity in BC cells, which may serve as a prominent novel therapeutic target for advanced breast cancer treatment.

Polyamine biosynthesis and eIF5A hypusination are modulated by the DNA tumor virus KSHV and promote KSHV viral infection

Polyamines are critical metabolites involved in various cellular processes and often dysregulated in cancers. Kaposi’s sarcoma-associated Herpesvirus (KSHV), a defined human oncogenic virus, leads to profound alterations of host metabolic landscape to favor development of KSHV-associated malignancies. In our studies, we identified that polyamine biosynthesis and eIF5A hypusination are dynamically regulated by KSHV infection through modulation of key enzymes (ODC1 and DHPS) of these pathways. During KSHV latency, ODC1 and DHPS are upregulated along with increase of hypusinated eIF5A (hyp-eIF5A), while hyp-eIF5A is further induced along with reduction of ODC1 and intracellular polyamines during KSHV lytic reactivation. In return these metabolic pathways are required for both KSHV lytic reactivation and de novo infection. Further analysis unraveled that synthesis of critical KSHV latent and lytic proteins (LANA, RTA) depends on hypusinated-eIF5A. We also demonstrated that KSHV infection can be efficiently and specifically suppressed by inhibitors targeting these pathways. Collectively, our results illustrated that the dynamic and profound interaction of a DNA tumor virus (KSHV) with host polyamine biosynthesis and eIF5A hypusination pathways promote viral propagation, thus defining new therapeutic targets to treat KSHV-associated malignancies.

Understanding virus-host interactions is crucial to develop and improve therapies. Kaposi’s sarcoma associated Herpesvirus (KSHV) is a human gamma-herpesvirus which deeply modulates the host metabolism and is associated with various cancers of endothelial and lymphoid origin. Polyamines are critical metabolites often dysregulated in cancers. In this study we demonstrated KSHV dynamically modulates polyamine metabolism to favor eIF5A hypusination and translation of critical KSHV latent and lytic proteins (LANA, RTA). Consequently, we found KSHV lytic switch from latency and de novo infection were dependent on polyamines and hypusination and pharmacological inhibition efficiently and specifically restricted KSHV infection. Our study provides new insights into KSHV alteration of the host metabolism and describe new therapeutic targets to treat KSHV-associated malignancies.

Polyamine Metabolites as Biomarkers in Head and Neck Cancer Biofluids

Background: Novel, non-invasive diagnostic biomarkers that facilitate early intervention in head and neck cancer are urgently needed. Polyamine metabolites have been observed to be elevated in numerous cancer types and correlated with poor prognosis. The aim of this study was to assess the concentration of polyamines in the saliva and urine from head and neck cancer (HNC) patients, compared to healthy controls. Methods: Targeted metabolomic analysis was performed on saliva and urine from 39 HNC patient samples and compared to 89 healthy controls using a quantitative, targeted liquid chromatography mass spectrometry approach. Results: The metabolites N¹-acetylspermine (ASP), N⁸-acetylspermidine (ASD) and N¹,N¹²-diacetylspermine (DAS) were detected at significantly different concentrations in the urine of HNC patients as compared to healthy controls. Only ASP was detected at elevated levels in HNC saliva as compared to healthy controls. Conclusion: These data suggest that assessment of polyamine-based metabolite biomarkers within the saliva and urine warrants further investigation as a potential diagnostic in HNC patients.

Angiocrine polyamine production regulates adiposity

Reciprocal interactions between endothelial cells (ECs) and adipocytes are fundamental to maintain white adipose tissue (WAT) homeostasis, as illustrated by the activation of angiogenesis upon WAT expansion, a process that is impaired in obesity. However, the molecular mechanisms underlying the crosstalk between ECs and adipocytes remain poorly understood. Here, we show that local production of polyamines in ECs stimulates adipocyte lipolysis and regulates WAT homeostasis in mice. We promote enhanced cell-autonomous angiogenesis by deleting Pten in the murine endothelium. Endothelial Pten loss leads to a WAT-selective phenotype, characterized by reduced body weight and adiposity in pathophysiological conditions. This phenotype stems from enhanced fatty acid β-oxidation in ECs concomitant with a paracrine lipolytic action on adipocytes, accounting for reduced adiposity. Combined analysis of murine models, isolated ECs and human specimens reveals that WAT lipolysis is mediated by mTORC1-dependent production of polyamines by ECs. Our results indicate that angiocrine metabolic signals are important for WAT homeostasis and organismal metabolism.

Polyamines: Α bioenergetic smart switch for plant protection and development

The present review highlights the bioenergetic role of polyamines in plant protection and development and proposes a universal model for describing polyamine-mediated stress responses. Any stress condition induces an excitation pressure on photosystem II by reforming the photosynthetic apparatus. To control this phenomenon, polyamines act directly on the molecular structure and function of the photosynthetic apparatus as well as on the components of the chemiosmotic proton-motive force (ΔpH/Δψ), thus regulating photochemical (qP) and non-photochemical quenching (NPQ) of energy. The review presents the mechanistic characteristics that underline the key role of polyamines in the structure, function, and bioenergetics of the photosynthetic apparatus upon light adaptation and/or under stress conditions. By following this mechanism, it is feasible to make stress-sensitive plants to be tolerant by simply altering their polyamine composition (especially the ratio of putrescine to spermine), either chemically or by light regulation.

PI3K-regulated Glycine N-methyltransferase is required for the development of prostate cancer

Glycine N-Methyltransferase (GNMT) is a metabolic enzyme that integrates metabolism and epigenetic regulation. The product of GNMT, sarcosine, has been proposed as a prostate cancer biomarker. This enzyme is predominantly expressed in the liver, brain, pancreas, and prostate tissue, where it exhibits distinct regulation. Whereas genetic alterations in GNMT have been associated to prostate cancer risk, its causal contribution to the development of this disease is limited to cell line-based studies and correlative human analyses. Here we integrate human studies, genetic mouse modeling, and cellular systems to characterize the regulation and function of GNMT in prostate cancer. We report that this enzyme is repressed upon activation of the oncogenic Phosphoinositide-3-kinase (PI3K) pathway, which adds complexity to its reported dependency on androgen signaling. Importantly, we demonstrate that expression of GNMT is required for the onset of invasive prostate cancer in a genetic mouse model. Altogether, our results provide further support of the heavy oncogenic signal-dependent regulation of GNMT in prostate cancer.

YAP/TAZ drives cell proliferation and tumour growth via a polyamine-eIF5A hypusination-LSD1 axis

Metabolic reprogramming is central to oncogene-induced tumorigenesis by providing the necessary building blocks and energy sources, but how oncogenic signalling controls metabolites that play regulatory roles in driving cell proliferation and tumour growth is less understood. Here we show that oncogene YAP/TAZ promotes polyamine biosynthesis by activating the transcription of the rate-limiting enzyme ornithine decarboxylase 1. The increased polyamine levels, in turn, promote the hypusination of eukaryotic translation factor 5A (eIF5A) to support efficient translation of histone demethylase LSD1, a transcriptional repressor that mediates a bulk of YAP/TAZ-downregulated genes including tumour suppressors in YAP/TAZ-activated cells. Accentuating the importance of the YAP/TAZ-polyamine-eIF5A hypusination-LSD1 axis, inhibiting polyamine biosynthesis or LSD1 suppressed YAP/TAZ-induced cell proliferation and tumour growth. Given the frequent upregulation of YAP/TAZ activity and polyamine levels in diverse cancers, our identification of YAP/TAZ as an upstream regulator and LSD1 as a downstream effector of the oncometabolite polyamine offers a molecular framework in which oncogene-induced metabolic and epigenetic reprogramming coordinately drives tumorigenesis, and suggests potential therapeutic strategies in YAP/TAZ- or polyamine-dependent human malignancies.

Microbiota Alterations and Their Association with Oncogenomic Changes in Pancreatic Cancer Patients

Pancreatic cancer (PC) is an aggressive disease with a high mortality and poor prognosis. The human microbiome is a key factor in many malignancies, having the ability to alter host metabolism and immune responses and participate in tumorigenesis. Gut microbes have an influence on physiological functions of the healthy pancreas and are themselves controlled by pancreatic secretions. An altered oral microbiota may colonize the pancreas and cause local inflammation by the action of its metabolites, which may lead to carcinogenesis. The mechanisms behind dysbiosis and PC development are not completely clear. Herein, we review the complex interactions between PC tumorigenesis and the microbiota, and especially the question, whether and how an altered microbiota induces oncogenomic changes, or vice versa, whether cancer mutations have an impact on microbiota composition. In addition, the role of the microbiota in drug efficacy in PC chemo- and immunotherapies is discussed. Possible future scenarios are the intentional manipulation of the gut microbiota in combination with therapy or the utilization of microbial profiles for the noninvasive screening and monitoring of PC.

The potential role of c-MYC and polyamine metabolism in multiple drug resistance in bladder cancer investigated by metabonomics

Bladder cancer has a high incidence worldwide accompanies by high recurrent rate after treatment. The emergence of primary or acquired chemotherapy resistance leads to poor efficacy in many cases. To explore the underlying mechanisms of drug resistance, we firstly established a drug-resistant cell model T24/THP by repeated exposure of T24 cells to pirarubicin (THP) whose concentration increases gradually. Non-targeted metabolomics was performed to identify metabolic changes and key metabolism pathways variance in T24/THP cells. Pathway enrichment analysis demonstrated that the arginine and proline metabolic pathway was the most significantly changed pathway, where two representative members of polyamine, putrescine and spermidine were remarkably down regulated in T24/THP. Subsequent experiments further confirmed that ornithine decarboxylase (ODC1) and spermidine synthase (SRM), the key enzymes involved in the synthesis of these compounds, also showed a stable low expression in T24/THP. However, knocking down of ODC1 and SRM sensitized cells to chemotherapy treatment while overexpression of these two enzymes enhances chemotherapy resistance. This leaded to the point that ODC1 and SRM themselves are more likely to promote the drug resistance, which appears to contradict their low expression in T24/THP. We hypothesize that their diminished levels were due to the declined activity of genes upstream. According to this line of thought, we found that c-MYC was also down-regulated in T24/THP and its content could be significantly affected by drug administration. In addition, c-MYC could not only regulate the expression levels of ODC1 and SRM but also influence drug resistance in T24/THP. In conclusion, alterations in gene expression of ODC1 and SRM in drug resistance cell line is probably mediated by some upstream regulators rather than antineoplastic agents alone. Exploration of upstream signals and research on detailed regulatory mechanism, thereby understanding the actual role of c-MYC and polyamine in response to chemotherapy, can become a potential field direction to overcome drug resistance in bladder cancer.

The endocytic pathway taken by cationic substances requires Rab14 but not Rab5 and Rab7

Endocytosis and endosome dynamics are controlled by proteins of the small GTPase Rab family. Besides possible recycling routes to the plasma membrane and various organelles, previously described endocytic pathways (e.g., clathrin-mediated endocytosis, macropinocytosis, CLIC/GEEC pathway) all appear to funnel the endocytosed material to Rab5-positive early endosomes that then mature into Rab7-positive late endosomes/lysosomes. By studying the uptake of a series of cell-penetrating peptides (CPPs), we identify an endocytic pathway that moves material to nonacidic Lamp1-positive late endosomes. Trafficking via this endocytic route is fully independent of Rab5 and Rab7 but requires the Rab14 protein. The pathway taken by CPPs differs from the conventional Rab5-dependent endocytosis at the stage of vesicle formation already, as it is not affected by a series of compounds that inhibit macropinocytosis or clathrin-mediated endocytosis. The Rab14-dependent pathway is also used by physiological cationic molecules such as polyamines and homeodomains found in homeoproteins.

Inhibition of Polyamine Biosynthesis Using Difluoromethylornithine Acts as a Potent Immune Modulator and Displays Therapeutic Synergy With PD-1-blockade

Polyamines are known to play a significant role in cancer progression and treatment using difluoromethylornithine (DFMO), an inhibitor of polyamine biosynthesis, has shown some clinical promise. It is interesting to note that, while DFMO is directly cytostatic in vitro, recent work has suggested that it achieves its antitumor efficacy in vivo by enhancing adaptive antitumor immune responses. On the basis of these data, we hypothesized that DFMO might act as an immune sensitizer to increase tumor responsiveness to checkpoint blockade. To test this hypothesis, we treated tumors with DFMO, in either the presence or absence of additional PD-1 blockade, and subsequently analyzed their immunological and therapeutic responses. Our data demonstrates that treatment with DFMO significantly enhances both the viability and activation status of intratumoral CD8+ T cells, most likely through an indirect mechanism. When combined with PD-1 blockade, this increased viability resulted in unique proinflammatory cytokine profiles and transcriptomes within the tumor microenvironment and improved therapeutic outcomes. Taken together, these data suggest that DFMO might represent a potential immunomodulatory agent that can enhance current PD-1-based checkpoint therapies.

Integrative Cistromic and Transcriptomic Analyses Identify CREB Target Genes in Cystic Renal Epithelial Cells

BACKGROUND

Genome-wide mapping of transcription factor (TF) binding sites is essential to identify a TF's direct target genes in kidney development and diseases. However, due to the cellular complexity of the kidney and limited numbers of a given cell type, it has been challenging to determine the binding sites of a TF in vivo. cAMP response element-binding protein (CREB) is phosphorylated and hyperactive in autosomal dominant polycystic kidney disease (ADPKD). We focus on CREB as an example to profile genomic loci bound by a TF and to identify its target genes using low numbers of specific kidney cells.

METHODS

Cleavage under targets and release using nuclease (CUT&RUN) assays were performed with Dolichos biflorus agglutinin (DBA)-positive tubular epithelial cells from normal and ADPKD mouse kidneys. Pharmacologic inhibition of CREB with 666-15 and genetic inhibition with A-CREB were undertaken using ADPKD mouse models.

RESULTS

CUT&RUN to profile genome-wide distribution of phosphorylated CREB (p-CREB) indicated correlation of p-CREB binding with active histone modifications (H3K4me3 and H3K27ac) in cystic epithelial cells. Integrative analysis with CUT&RUN and RNA-sequencing revealed CREB direct targets, including genes involved in ribosome biogenesis and protein synthesis. Pharmacologic and genetic inhibition of CREB suppressed cyst growth in ADPKD mouse models.

CONCLUSIONS

CREB promotes cystogenesis by activating ribosome biogenesis genes. CUT&RUN, coupled with transcriptomic analysis, enables interrogation of TF binding and identification of direct TF targets from a low number of specific kidney cells.

Relationships of Gut Microbiota Composition, Short-Chain Fatty Acids and Polyamines with the Pathological Response to Neoadjuvant Radiochemotherapy in Colorectal Cancer Patients

Emerging evidence has suggested that dysbiosis of the gut microbiota may influence the drug efficacy of colorectal cancer (CRC) patients during cancer treatment by modulating drug metabolism and the host immune response. Moreover, gut microbiota can produce metabolites that may influence tumor proliferation and therapy responsiveness. In this study we have investigated the potential contribution of the gut microbiota and microbial-derived metabolites such as short chain fatty acids and polyamines to neoadjuvant radiochemotherapy (RCT) outcome in CRC patients. First, we established a profile for healthy gut microbiota by comparing the microbial diversity and composition between CRC patients and healthy controls. Second, our metagenomic analysis revealed that the gut microbiota composition of CRC patients was relatively stable over treatment time with neoadjuvant RCT. Nevertheless, treated patients who achieved clinical benefits from RTC (responders, R) had significantly higher microbial diversity and richness compared to non-responder patients (NR). Importantly, the fecal microbiota of the R was enriched in butyrate-producing bacteria and had significantly higher levels of acetic, butyric, isobutyric, and hexanoic acids than NR. In addition, NR patients exhibited higher serum levels of spermine and acetyl polyamines (oncometabolites related to CRC) as well as zonulin (gut permeability marker), and their gut microbiota was abundant in pro-inflammatory species. Finally, we identified a baseline consortium of five bacterial species that could potentially predict CRC treatment outcome. Overall, our results suggest that the gut microbiota may have an important role in the response to cancer therapies in CRC patients.

Characterization of nanoparticles combining polyamine detection with photodynamic therapy

Polyamine detection and depletion have been extensively investigated for cancer prevention and treatment. However, the therapeutic efficacy is far from satisfactory, mainly due to a polyamine compensation mechanism from the systemic circulation in the tumor environment. Herein, we explore a new solution for improving polyamine detection as well as a possible consumption therapy based on a new photosensitizer that can efficiently consume polyamines via an irreversible chemical reaction. The new photosensitizer is pyrrolopyrroleaza-BODIPY pyridinium salt (PPAB-PyS) nanoparticles that can react with the over-expressed polyamine in cancer cells and produce two photosensitizers with enhanced phototoxicity on cancer destruction. Meanwhile, PPAB-PyS nanoparticles provide a simultaneous ratiometric fluorescence imaging of intracellular polyamine. This combination polyamine consumption with a chemical reaction provides a new modality to enable polyamine detection along with photodynamic therapy as well as a putative depletion of polyamines for cancer treatment and prevention.

A pan-cancer transcriptomic study showing tumor specific alterations in central metabolism

Recently, there has been a resurgence of interest in metabolic rewiring of tumors to identify clinically relevant genes. However, most of these studies have had either focused on individual tumors, or are too general, providing a broad outlook on overall changes. In this study, we have first curated an extensive list of genes encoding metabolic enzymes and metabolite transporters relevant to carbohydrate, fatty acid and amino acid oxidation and biosynthesis. Next, we have used publicly available transcriptomic data for 20 different tumor types from The Cancer Genome Atlas Network (TCGA) and focused on differential expression of these genes between tumor and adjacent normal tissue. Our study revealed major transcriptional alterations in genes that are involved in central metabolism. Most tumors exhibit upregulation in carbohydrate and amino acid transporters, increased glycolysis and pentose phosphate pathway, and decreased fatty acid and amino acid oxidation. On the other hand, the expression of genes of the tricarboxylic acid cycle, anaplerotic reactions and electron transport chain differed between tumors. Although most transcriptomic alterations were conserved across many tumor types suggesting the initiation of common regulatory programs, expression changes unique to specific tumors were also identified, which can provide gene expression fingerprints as potential biomarkers or drug targets. Our study also emphasizes the value of transcriptomic data in the deeper understanding of metabolic changes in diseases.

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.

The Polyamine Regulator AMD1 Upregulates Spermine Levels to Drive Epidermal Differentiation

Maintaining tissue homeostasis depends on a balance between cell proliferation, differentiation, and apoptosis. Within the epidermis, the levels of the polyamines putrescine, spermidine, and spermine are altered in many different skin conditions, yet their role in epidermal tissue homeostasis is poorly understood. We identify the polyamine regulator, Adenosylmethionine decarboxylase 1 (AMD1), as a crucial regulator of keratinocyte (KC) differentiation. AMD1 protein is upregulated on differentiation and is highly expressed in the suprabasal layers of the human epidermis. During KC differentiation, elevated AMD1 promotes decreased putrescine and increased spermine levels. Knockdown or inhibition of AMD1 results in reduced spermine levels and inhibition of KC differentiation. Supplementing AMD1-knockdown KCs with exogenous spermidine or spermine rescued aberrant differentiation. We show that the polyamine shift is critical for the regulation of key transcription factors and signaling proteins that drive KC differentiation, including KLF4 and ZNF750. These findings show that human KCs use controlled changes in polyamine levels to modulate gene expression to drive cellular behavior changes. Modulation of polyamine levels during epidermal differentiation could impact skin barrier formation or can be used in the treatment of hyperproliferative skin disorders.

Integrative Treatment of Lung Cancer Patients: Observational Study of 57 Cases

Introduction A retrospective clinical study was performed to identify the characteristics of patients with lung cancer treated with integrative cancer treatment in addition to conventional medicine.

Materials and Methods We reviewed medical records for lung cancer patients who visited a single integrative setting in Rome, Italy. A total of 57 patients were included, and the majority had advanced-stage cancer. All of them underwent integrative therapy with nutrition and phytotherapy indications. The diet was designed to reduce most of possible factors promoting cancer proliferation, inflammation, and obesity. Foods with anti-inflammatory, prebiotic, antioxidant, and anticancer properties had been chosen. Herbal supplements with known effects on lung cancer were prescribed. In particular, astragal, apigenine, fucosterol, polydatin, epigallocatechin gallate, cannabis, curcumin, and inositol were used. Furthermore, medical mushrooms and other substances were used to improve the immune system and to reduce chemotherapy side effects. Five key parameters have been evaluated for 2 years starting at the first surgery: nutritional status, immune status, discontinuation of therapy, quality of life, and prognosis of the disease.

Results A relevant improvement in parameters relative to nutritional status, immune status, and quality of life has been observed after integrative therapy compared with the same parameters at the first medical visit before starting such approach.

Conclusion The results suggest that integrative therapy may have benefits in patients with lung cancer. Even though there are limitations, the study suggests that integrative therapy could improve nutritional status and quality of life, with possible positive effect on overall survival.

Mitochondrial NADP+ is essential for proline biosynthesis during cell growth

Nicotinamide adenine dinucleotide phosphate (NADP⁺) is vital to produce NADPH, a principal supplier of reducing power for biosynthesis of macromolecules and protection against oxidative stress. NADPH exists in separate pools, in both the cytosol and mitochondria; however, the cellular functions of mitochondrial NADPH are incompletely described. Here, we find that decreasing mitochondrial NADP(H) levels through depletion of NAD kinase 2 (NADK2), an enzyme responsible for production of mitochondrial NADP⁺, renders cells uniquely proline auxotrophic. Cells with NADK2 deletion fail to synthesize proline, due to mitochondrial NADPH deficiency. We uncover the requirement of mitochondrial NADPH and NADK2 activity for the generation of the pyrroline-5-carboxylate metabolite intermediate as the bottleneck step in the proline biosynthesis pathway. Notably, after NADK2 deletion, proline is required to support nucleotide and protein synthesis, making proline essential for the growth and proliferation of NADK2-deficient cells. Thus, we highlight proline auxotrophy in mammalian cells and discover that mitochondrial NADPH is essential to enable proline biosynthesis.

Metformin Inhibits the Urea Cycle and Reduces Putrescine Generation in Colorectal Cancer Cell Lines

The urea cycle (UC) removes the excess nitrogen and ammonia generated by nitrogen-containing compound composites or protein breakdown in the human body. Research has shown that changes in UC enzymes are not only related to tumorigenesis and tumor development but also associated with poor survival in hepatocellular, breast, and colorectal cancers (CRC), etc. Cytoplasmic ornithine, the intermediate product of the urea cycle, is a specific substrate for ornithine decarboxylase (ODC, also known as ODC1) for the production of putrescine and is required for tumor growth. Polyamines (spermidine, spermine, and their precursor putrescine) play central roles in more than half of the steps of colorectal tumorigenesis. Given the close connection between polyamines and cancer, the regulation of polyamine metabolic pathways has attracted attention regarding the mechanisms of action of chemical drugs used to prevent CRC, as the drug most widely used for treating type 2 diabetes (T2D), metformin (Met) exhibits antitumor activity against a variety of cancer cells, with a vaguely defined mechanism. In addition, the influence of metformin on the UC and putrescine generation in colorectal cancer has remained unclear. In our study, we investigated the effect of metformin on the UC and putrescine generation of CRC in vivo and in vitro and elucidated the underlying mechanisms. In nude mice bearing HCT116 tumor xenografts, the administration of metformin inhibited tumor growth without affecting body weight. In addition, metformin treatment increased the expression of monophosphate (AMP)-activated protein kinase (AMPK) and p53 in both HCT116 xenografts and colorectal cancer cell lines and decreased the expression of the urea cycle enzymes, including carbamoyl phosphate synthase 1 (CPS1), arginase 1 (ARG1), ornithine trans-carbamylase (OTC), and ODC. The putrescine levels in both HCT116 xenografts and HCT116 cells decreased after metformin treatment. These results demonstrate that metformin inhibited CRC cell proliferation via activating AMPK/p53 and that there was an association between metformin, urea cycle inhibition and a reduction in putrescine generation.