Polyamine Structure and Synthetic Analogs

Accumulating evidence indicate that astrocytes are essential players of the excitatory and inhibitory signaling during normal and epileptiform activity via uptake and release of gliotransmitters, ions, and other substances. Polyamines can be regarded as gliotransmitters since they are almost exclusively stored in astrocytes and can be released by various mechanisms. The polyamine putrescine (PUT) is utilized to synthesize GABA, which can also be released from astrocytes and provide tonic inhibition on neurons. The polyamine spermine (SPM), synthesized form PUT through spermidine (SPD), is known to unblock astrocytic Cx43 gap junction channels and therefore facilitate astrocytic synchronization. In addition, SPM released from astrocytes may also modulate neuronal NMDA, AMPA, and kainate receptors. As a consequence, astrocytic polyamines possess the capability to significantly modulate epileptiform activity. In this study, we investigated different steps in polyamine metabolism and coupled GABA release to assess their potential to control seizure generation and maintenance in two different epilepsy models: the low-[Mg2+] model of temporal lobe epilepsy in vitro and in the WAG/Rij rat model of absence epilepsy in vivo. We show that SPM is a gliotransmitter that is released from astrocytes and significantly contributes to network excitation. Importantly, we found that inhibition of SPD synthesis completely prevented seizure generation in WAG/Rij rats. We hypothesize that this antiepileptic effect is attributed to the subsequent enhancement of PUT to GABA conversion in astrocytes, leading to GABA release through GAT-2/3 transporters. This interpretation is supported by the observation that antiepileptic potential of the Food and Drug Administration (FDA)-approved drug levetiracetam can be diminished by specifically blocking astrocytic GAT-2/3 with SNAP-5114, suggesting that levetiracetam exerts its effect by increasing surface expression of GAT-2/3. Our findings conclusively suggest that the major pathway through which astrocytic polyamines contribute to epileptiform activity is the production of GABA. Modulation of astrocytic polyamine levels, therefore, may serve for a more effective antiepileptic drug development in the future.

Diseases caused by parasitic organisms are a significant component of global morbidity and represent a serious challenge for drug discovery and development. Because polyamines are absolutely required for growth, survival and cellular homeostasis in parasitic organisms, polyamine metabolism is an important target for the discovery of antiparasitic agents. The rational design of antiparasitic agents that target the polyamine pathway relies on the fact that there are significant differences between human and parasitic polyamine metabolism. However, polyamine metabolism in these parasitic organisms is as diverse as the parasites themselves. As a result, a thorough understanding of polyamine metabolism in each organism, and of the structural differences in enzymes involved in this pathway, greatly facilitates the drug discovery process. In this chapter, the current understanding of polyamine metabolism in various organisms is described. In addition, recent efforts to specifically target parasitic enzymes involved in polyamine metabolism, or to modulate parasitic metabolic processes that are not found in humans, are described.

Polyamine metabolism is essential for cancer cell growth, with enzymes like ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (AdoMetDC) playing key roles in polyamine (PA) biosynthesis. These polyamines (putrescine, spermidine, and spermine) regulate vital cellular processes, including DNA replication, protein synthesis, and cell cycle progression. Dysregulated polyamine metabolism is common in cancer, making ODC and AdoMetDC attractive therapeutic targets. This review highlights polyamines' role in cancer and explores combination therapies targeting polyamine metabolism and critical signaling pathways for improved clinical outcomes. A comprehensive analysis of both historical and recent literature on polyamine metabolism in cancer was performed using PubMed, which provides access to over 37 million citations from biomedical literature. Expression data for key polyamine biosynthetic enzymes, ODC and AdoMetDC, were obtained from the UALCAN portal - an interactive web resource for the analysis of cancer OMICS data. The IUPAC names of drugs and inhibitors targeting the polyamine pathway were retrieved from the PubChem database and used to generate molecular structures using the BIOVIA Draw 2025 program. Additionally, the ClinicalTrials.gov database was explored to identify ongoing and completed clinical research studies, as well as to gather detailed information on therapeutic agents targeting polyamine metabolism. Aberrant polyamine metabolism in cancer is driven by oncogenic pathways like MYC, Akt, and mTOR. MYC upregulates ODC1, promoting polyamine dysregulation. Defects in enzymes such as MTA phosphorylase (MTAP) enhance cancer cell sensitivity to inhibitors of purine/pyrimidine synthesis and the ubiquitin-proteasome pathway, suggesting alternative therapeutic strategies. Therapeutic strategies combining polyamine biosynthesis inhibition with targeting nucleotide synthesis or proteasome function have shown synergistic potential. However, the dual nature of polyamines - supporting both, tumor growth and ferroptotic cell death - poses a therapeutic challenge. Balancing these effects is key to designing effective interventions. Advancing this field requires not only selective inhibitors but also a deeper understanding of context-dependent polyamine functions in tumor biology. Developing more potent inhibitors with improved drug-like properties is crucial for advancing polyamine- targeted therapies and positioning this field at the forefront of cancer research.

The polyamines putrescine, spermidine and spermine are organic cations shown to participate in a bewildering number of cellular reactions, yet their exact functions in intermediary metabolism and specific interactions with cellular components remain largely elusive. Pharmacological interventions have demonstrated convincingly that a steady supply of these compounds is a prerequisite for cell proliferation to occur. The last decade has witnessed the appearance of a substantial number of studies, in which genetic engineering of polyamine metabolism in transgenic rodents has been employed to unravel their cellular functions. Transgenic activation of polyamine biosynthesis through an overexpression of their biosynthetic enzymes has assigned specific roles for these compounds in spermatogenesis, skin physiology, promotion of tumorigenesis and organ hypertrophy as well as neuronal protection. Transgenic activation of polyamine catabolism not only profoundly disturbs polyamine homeostasis in most tissues, but also creates a complex phenotype affecting skin, female fertility, fat depots, pancreatic integrity and regenerative growth. Transgenic expression of ornithine decarboxylase antizyme has suggested that this unique protein may act as a general tumor suppressor. Homozygous deficiency of the key biosynthetic enzymes of the polyamines, ornithine and S-adenosylmethionine decarboxylase, as achieved through targeted disruption of their genes, is not compatible with murine embryogenesis. Finally, the first reports of human diseases apparently caused by mutations or rearrangements of the genes involved in polyamine metabolism have appeared.

Among histamine-containing cells, mast cells (MCs) are immediately associated with allergic diseases and other pathologies. After leaving the bone marrow as immature precursors, MCs differentiate under the infl uence of micro-environmental stimuli within the peripheral tissues, where they synthesize and store several mediators including histamine, cytokines and MC proteases [1]. As with any other cell type, MCs also require polyamines (putrescine, spermidine and spermine) for macromolecular synthesis and proliferation [2]. Working with MC-like cell lines, we have previously observed that treatments which increase intracellular histamine levels provoke a downregulation of total polyamines at the expense of different mechanisms [3, 4]. These observations indicated an antagonism between both metabolisms in this cell type. However, MC-like cell lines, due to their lack of many MC-features, represent a poor counterpart of the mature MCs that reside in the body, and they do not constitute a suitable model to study any putative relationship between histamine and polyamine metabolism during the course of the MCs differentiation. Here we show that bone marrow derived MCs (BMMCs), which represent a better approach to this cell type, provide an excellent model to characterize both histamine and polyamines metabolism and their antagonistic interplay during the differentiation of MCs from their cell precursors in the bone marrow.

Tuberous sclerosis complex (TSC) is an autosomal dominant neurodevelopmental disorder and the quintessential disorder of mechanistic Target of Rapamycin Complex 1 (mTORC1) dysregulation. Loss of either causative gene, TSC1 or TSC2, leads to constitutive mTORC1 kinase activation and a pathologically anabolic state of macromolecular biosynthesis. Little is known about the organ-specific metabolic reprogramming that occurs in TSC-affected organs. Using a mouse model of TSC in which Tsc2 is disrupted in radial glial precursors and their neuronal and glial descendants, we performed an unbiased metabolomic analysis of hippocampi to identify Tsc2-dependent metabolic changes. Significant metabolic reprogramming was found in well-established pathways associated with mTORC1 activation, including redox homeostasis, glutamine/tricarboxylic acid cycle, pentose and nucleotide metabolism. Changes in two novel pathways were identified: transmethylation and polyamine metabolism. Changes in transmethylation included reduced methionine, cystathionine, S-adenosylmethionine (SAM-the major methyl donor), reduced SAM/S-adenosylhomocysteine ratio (cellular methylation potential), and elevated betaine, an alternative methyl donor. These changes were associated with alterations in SAM-dependent methylation pathways and expression of the enzymes methionine adenosyltransferase 2A and cystathionine beta synthase. We also found increased levels of the polyamine putrescine due to increased activity of ornithine decarboxylase, the rate-determining enzyme in polyamine synthesis. Treatment of Tsc2+/- mice with the ornithine decarboxylase inhibitor α-difluoromethylornithine, to reduce putrescine synthesis dose-dependently reduced hippocampal astrogliosis. These data establish roles for SAM-dependent methylation reactions and polyamine metabolism in TSC neuropathology. Importantly, both pathways are amenable to nutritional or pharmacologic therapy.

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.

Corona virus is quickly spreading around the world. The goal of viral management is to disrupt the virus’s life cycle, minimize lung damage, and alleviate severe symptoms. Numerous strategies have been used, including repurposing existing antivirals or drugs used in previous viral outbreaks. One such strategy is to repurpose FDA-approved kinase inhibitors that are potential chemotherapeutic agents and have demonstrated antiviral activity against a variety of viruses, including MERS, SARS-CoV-1, and others, by inhibiting the viral life cycle and the inflammatory response associated with COVID-19. The purpose of this article is to identify licensed kinase inhibitors that have the ability to reduce the virus’s life cycle, from entrance through viral propagation from cell to cell. Several of these inhibitors, including imatinib, ruxolitinib, silmitasertib, and tofacitinib (alone and in conjunction with hydroxychloroquine), are now undergoing clinical studies to determine their efficacy as a possible treatment drug. The FDA approved baricitinib (a Janus kinase inhibitor) in combination with remdesivir for the treatment of COVID-19 patients receiving hospital care in November 2020. While in vitro trials with gilteritinib, fedratinib, and osimertinib are encouraging, further research is necessary before these inhibitors may be used to treat COVID-19 patients.

The content of water-insoluble amine conjugates (di-feruloylputrescine, di-feruloyl- spermidine, feruloytyramine) decreased drastically during tobacco germination, concomitantly with a rapid increase in free polyamines (putrescine, spermidine, tyramine). Neither DFMA nor DFMO inhibited the emergence of the radicle, which is considered to be the end of the germination process, nor where the putrescine and spermidine titers modified during the first two days. We present evidence that ADC and ODC regulate putrescine biosynthesis at different stages of tobacco root development, with ADC being active early in development and ODC later. Arginine decarboxylase reached a peak on day 3 of germination (Fig. 1) and was required for root elongation. Ornithine decarboxylase activity peaked 3 days after emergence of the radicle (Fig. 2), and was required for subsequent root development and branching. When ADC action was blocked by DFMA, polyamine diminished only during the first few days of development; when agmatine or putrescine were added, normal polyamine titers and growth were restored. The effects of DFMA were concentration dependent. DFMO promoted root elongation during the first few days of seedling development. This effect of DFMO is related to the observed enhancement of plant ADC and accumulation of polyamines. Fundamental changes in growth and tobacco root development were associated with inhibition of ODC by DFMO (root elongation was stopped, and no, or only limited ramification, was observed during the whole period of development). They correlated with the inhibition of the production of free polyamines, and with inhibition of putrescine conjugates. Our results lead to the following conclusions: ADC leads to the production of free polyamines which are required for growth by cell expansion; ODC is required for cell division and differentiation; putrescine conjugates are important in

The study aims (1) to evaluate the effect of Mesorhizobium tianshanense on plant proline and polyamine levels of Lotus tenuis and its modulatory effect during plant response to short-term salt stress and (2) to compare these effects with those caused by mycorrhizal symbiosis. Experiments consisted of a randomized factorial design of two factors: salinity (two levels, 0 and 150 mM NaCl) and symbiosis (three levels, uninoculated, Glomus intraradices, and M. tianshanense). Salinization led to increased proline levels regardless of plant organ and symbiotic status, excepting mycorrhizal L. tenuis roots. Salinity diminished the total polyamine level of control and rhizobial plants but not in mycorrhizal ones. Variations in the pattern response of the three individual polyamines (putrescine, spermidine, and spermine) differed in accordance with the symbiotic status of the plant, highlighting a divergence on proline and polyamine metabolisms between rhizobial and mycorrhizal symbiosis. Spermidine and spermine contributed the most with the salt-induced root polyamine increment observed upon salinization in roots of nodulated plants, suggesting that these polyamines might mediate an adaptive role of the plant–M. tianshanense symbiosis in L. tenuis plants growing in a saline environment.

Translating advances in cancer research to clinical applications requires better insight into the metabolism of normal cells and tumour cells in vivo. Much effort has focused on understanding how glycolysis and oxidative phosphorylation (OxPhos) support proliferation, while their impact on other aspects of development and tumourigenesis remain largely unexplored. We found that inhibition of OxPhos in neural stem cells (NSCs) or tumours in the Drosophila brain not only decreases proliferation, but also affects many different aspects of stem cell behaviour. In NSCs, OxPhos dysfunction leads to a protracted G1/S-phase and results in delayed temporal patterning and reduced neuronal diversity. As a consequence, NSCs fail to undergo terminal differentiation, leading to prolonged neurogenesis into adulthood. Similarly, in brain tumours inhibition of OxPhos slows proliferation and prevents differentiation, resulting in reduced tumour heterogeneity. Thus, in vivo, highly proliferative stem cells and tumour cells require OxPhos for efficient growth and generation of diversity.

Structural and spectroscopic characterization of a novel potential chemotherapeutic agent 3-(1-adamantyl)-1-{[4-(2-methoxyphenyl)piperazin-1-yl]methyl}-4-methyl-1H-1,2,4-triazole-5(4H)-thione by first principle calculations

Evaluation of Jatropha isabelli natural products and their synthetic analogs as potential antimalarial therapeutic agents

Enhanced gene transfection of macrophages by photochemical internalization: Potential for gene-directed enzyme prodrug therapy of gliomas.

Epigenetic modulators in combination with proapoptotic drugs have become a standard of treatment for acute myeloid leukemia. However, the clinical efficacy of these combinations in solid tumors has shown to be negligible. Our group has demonstrated that the epigenetic drug CM272, which targets DNMT and G9a, induces synergistic responses in combination with proapoptotic drugs in hematological malignancies (Cancer Discovery 2021). We have also reported that CM272 induces an immunogenic cell death that sensitizes tumor cells to immune checkpoint blockade (ICB) (Nature Medicine 2020). Here, we hypothesized that CM272 in combination with proapoptotic drugs may sensitize tumor cells to ICB, resulting in profound anti-tumor responses. To test this hypothesis, we evaluated in vitro the sensitivity of cancer cells to different combinations of epigenetic and proapoptotic drugs. The most efficient combination was tested in various immunocompetent mouse models, followed by an immunophenotypic characterization of the tumor microenvironment. We found that CM272 in combination with inhibitors of BCL-XL, BCL2 or MCL1, yielded synergistic in vitro responses in a large collection of human and mouse cell lines derived from solid tumors. Mechanistically, the treatments induced the expression of endogenous retroelements/retroviruses, which led to the activation of RIG-1 and MDA5 viral sensors, ATP hydrolysis and tumor cell death. Remarkably, we found that CM272 in combination with BCL-XL inhibition had more potent anti-tumor effects than that found with BCL2 or MCL1 inhibitors. In vivo, the triple combination CM272, A1331852 (BCL-XL inhibitor) and an anti-PD-1 moAb significantly reduced tumor growth and increased overall survival in three subcutaneous lung cancer models (LLC, 393P, Lacun-3) in comparison to double treatments. Moreover, this triple combination also induced significant anti-tumor responses in subcutaneous mouse models of colon cancer (MC38) and melanoma (B16), as well as in orthotopic models of lung cancer (LLC), glioblastoma (CT-2A) and breast cancer (ANV5), leading to prolonged survival and cure in a fraction of animals. The triple therapy was associated with a significant increase in the ratio of CD8 T versus immunosuppressive Treg cells, and M1 versus M2 macrophages. In conclusion, we report a novel regimen combining a dual epigenetic inhibitor, an anti-BCL-XL, and an anti-PD-1 moAb that results in potent responses in multiple pre-clinical models of solid tumors. The mechanisms underneath the antitumor responses include the modulation of the energy metabolism in tumor cells, leading to cell death boosted by an anti-BCL-XL pro-apoptotic drug, along with fostering the immune system to generate an efficient anti-tumor response assisted by ICB. This study reveals the potential of epigenetic therapeutics to treat and cure patients with solid tumors. Citation Format: Yaiza Senent, Vicente Fresquet, Victoria Jimenez, Karmele Valencia, Ana Remirez, Francisco Exposito, Marisol Gonzalez-Huarriz, Borja Ruiz-Fernandez de Cordoba, Haritz Moreno, Daniel Ajona, Marta M Alonso, Fernando Lecanda, Antonio Pineda-Lucena, Felipe Prosper, Alfonso Calvo, Jose Angel Martinez-Climent, Ruben Pio. Combined treatment with the epigenetic drug CM272 and an anti-BCL-XL proapoptotic drug sensitizes solid tumors to immune checkpoint blockade. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5117.