Polyamines and colon cancer

New insights into the toxicological effects of dietary biogenic amines

Biogenic amines (BA) are molecules with biological functions, which can accumulate at toxic concentrations in foods. Several microorganisms have been identified as responsible for their accumulation at elevated concentrations. Histamine, tyramine and putrescine are the BA most commonly found at highest concentrations. The ingestion of food containing high BA concentrations leads to intoxication with symptoms depending on the BA and the amount consumed. Moreover, there is evidence of synergy between different BA, something of toxicological importance given that some foods accumulate different BA. This work reviews the BA toxic effects and examines recent discoveries regarding their synergy, cytotoxicity and genotoxicity. These advances in the toxicological consequences of ingesting BA contaminated foods support the need to regulate their presence in foods to preserve the consumer's health. However, more research efforts -focused on the establishment of risk assessments- are needed to reach a consensus in their limits in different food matrices.

Potential of fermented foods and their metabolites in improving gut microbiota function and lowering gastrointestinal inflammation

Foods prepared using microbial conversion of major and minor food components, which are otherwise known as fermented foods continue to impact human health. The live microorganisms and transformed metabolites can also have a deep influence on the gut microbiota, the multifaceted population of microorganisms dwelling inside the gut play a key role in wellbeing of an individual. The probiotic strains delivered through the consumption of fermented food and other bioactive components such as polyphenolic metabolites, bioactive peptides, short-chain fatty acids and others including those produced via gut microbiota mediated transformations have been proposed to balance the gut microbiota diversity and activity, and also to regulate the inflammation in the gut. However, little is known about such effects and only a handful of fermented foods have been explored to date. We herein review the recent knowledge on the dysbiotic gut microbiota linking to major gut inflammatory diseases. Also, evidences that fermented food consumption modulates the gut microbiota, and its impact on the gut inflammation and inflammatory diseases have been discussed. © 2024 Society of Chemical Industry.

Polystyrene microplastics induce size-dependent multi-organ damage in mice: Insights into gut microbiota and fecal metabolites

Particle size is one of the most important factors in determining the biological toxicity of microplastics (MPs). In this study, we attempted to examine the systemic toxicity of polystyrene MPs of different sizes (0.5 µm MP1 and 5 µm MP2) in C57BL/6 J mice. After the mice were given oral gavage of MPs for 8 consecutive weeks, histopathology and molecular biology assays, 16 S rRNA sequencing of the gut microbiota, and untargeted metabolomics were performed. The results showed that MPs were distributed in the organs in a size-dependent manner, with smaller particles demonstrating greater biodistribution. Further analysis indicated that exposure to MPs caused multi-organ damage through distinct toxicity pathways. Specifically, exposure to 0.5 µm MP1 led to excessive accumulation and induced more serious inflammation and mechanical damage in the spleen, kidney, heart, lung, and liver. However, 5 µm MP2 led to more severe intestinal barrier dysfunction, as well as gut dysbiosis and metabolic disorder in association with neuroinflammation. These results are helpful in expanding our knowledge of the toxicity of MPs of different sizes in mammalian models.

Carrier-Mediated Process of Putrescine Elimination at the Rat Blood-Retinal Barrier

Putrescine is a bioactive polyamine. Its retinal concentration is strictly controlled to maintain a healthy sense of vision. The present study investigated putrescine transport at the blood-retinal barrier (BRB) to gain a better understanding of the mechanisms of putrescine regulation in the retina. Our microdialysis study showed that the elimination rate constant during the terminal phase was significantly greater (1.90-fold) than that of [¹⁴C]D-mannitol, which is a bulk flow marker. The difference in the apparent elimination rate constants of [³H]putrescine and [¹⁴C]D-mannitol was significantly decreased by unlabeled putrescine and spermine, suggesting active putrescine transport from the retina to the blood across the BRB. Our study using model cell lines of the inner and outer BRB showed that [³H]putrescine transport was time-, temperature-, and concentration-dependent, suggesting the involvement of carrier-mediated processes in putrescine transport at the inner and outer BRB. [³H]Putrescine transport was significantly reduced under Na⁺-free, Cl^--free, and K⁺-replacement conditions, and attenuated by polyamines or organic cations such as choline, a choline transporter-like protein (CTL) substrate. Rat CTL1 cRNA-injected oocytes exhibited marked alterations in [³H]putrescine uptake, and CTL1 knockdown significantly reduced [³H]putrescine uptake in model cell lines, suggesting the possible participation of CTL1 in putrescine transport at the BRB.

The Role of Microbiota-Derived Metabolites in Colorectal Cancer

The impact of bacterial members of the microbiota on the development of colorectal cancer (CRC) has become clear in recent years. However, exactly how bacteria contribute to the development of cancer is often still up for debate. The impact of bacteria-derived metabolites, which can influence the development of CRC either in a promoting or inhibiting manner, is undeniable. Here, we discuss the effects of the most well-studied bacteria-derived metabolites associated with CRC, including secondary bile acids, short-chain fatty acids, trimethylamine-N-oxide and indoles. We show that the effects of individual metabolites on CRC development are often nuanced and dose- and location-dependent. In the coming years, the array of metabolites involved in CRC development will undoubtedly increase further, which will emphasize the need to focus on causation and mechanisms and the clearly defined roles of bacterial species within the microbiota.

Microbial Metabolite Dysbiosis and Colorectal Cancer

The global burden of colorectal cancer (CRC) is expected to continuously increase. Through research performed in the past decades, the effects of various environmental factors on CRC development have been well identified. Diet, the gut microbiota and their metabolites are key environmental factors that profoundly affect CRC development. Major microbial metabolites with a relevance for CRC prevention and pathogenesis include dietary fiber-derived short-chain fatty acids, bile acid derivatives, indole metabolites, polyamines, trimethylamine-N-oxide, formate, and hydrogen sulfide. These metabolites regulate various cell types in the intestine, leading to an altered intestinal barrier, immunity, chronic inflammation, and tumorigenesis. The physical, chemical, and metabolic properties of these metabolites along with their distinct functions to trigger host receptors appear to largely determine their effects in regulating CRC development. In this review, we will discuss the current advances in our understanding of the major CRC-regulating microbial metabolites, focusing on their production and interactive effects on immune responses and tumorigenesis in the colon.

Exploring the effect of polyamines on NK cell function in colorectal cancer process based on glycolysis

Natural killer (NK) cells are lymphocytes with important anti-tumour functions. Cellular metabolism is dynamically regulated in NK cells and strongly influences their responses. Myc is a key regulator of immune cell activity and function, but little is known about how Myc controls NK cell activation and function. In this study, we found that c-Myc is involved in the regulation of NK cell immune activity. In the development of colon cancer, the energy generation disorder of tumor cells promotes the plunder of polyamines of NK cells by tumor cells, resulting in the inhibition of NK cell c-Myc. After inhibition of c-Myc, glycolysis of NK cells was impaired, resulting in decreased killing activity. There are three main types of polyamines: putrescine (Put), spermidine (Spd) and spermine (Spm). We found that the NK cells could reverse the inhibition state of c-Myc and glycolysis energy supply disorder and recover the killing activity of NK cells after giving certain spermidine. These results suggest that polyamine content and glycolysis supply under the regulation of c-Myc play a crucial role in the immune activity of NK cells.

Quantitative Metabolomics to Explore the Role of Plasma Polyamines in Colorectal Cancer

Colorectal cancer (CRC) is one of the major public health and socio-economic problems, which management demands the development of non-invasive screening tests. Assessment of circulating polyamines could be a valuable tool, although analytical problems still preclude its clinical practice. We exploited ultra-high-resolution liquid chromatography and mass spectrometry, as a highly sensitive and innovative method, to profile eleven polyamines, including spermine and spermidine with their acetylated forms. These data together with an evaluation of the inflammatory indexes might represent suitable biomarkers for the identification of CRC patients. The statistical models revealed good discrimination in distinguishing CRC patients from healthy subjects. The plasma assessment of ornithine and acetylspermine, as well as lymphocyte/platelet ratio, revealed helpful information on the progression of CRC. The combined profiles of circulating polyamines and inflammatory indexes, together with the application of an innovative technology, could represent a valuable tool for discriminating patients from different clinical groups.

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.

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.

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.

Metabolic Reprogramming of Colorectal Cancer Cells and the Microenvironment: Implication for Therapy

Colorectal carcinoma (CRC) is one of the most frequently diagnosed carcinomas and one of the leading causes of cancer-related death worldwide. Metabolic reprogramming, a hallmark of cancer, is closely related to the initiation and progression of carcinomas, including CRC. Accumulating evidence shows that activation of oncogenic pathways and loss of tumor suppressor genes regulate the metabolic reprogramming that is mainly involved in glycolysis, glutaminolysis, one-carbon metabolism and lipid metabolism. The abnormal metabolic program provides tumor cells with abundant energy, nutrients and redox requirements to support their malignant growth and metastasis, which is accompanied by impaired metabolic flexibility in the tumor microenvironment (TME) and dysbiosis of the gut microbiota. The metabolic crosstalk between the tumor cells, the components of the TME and the intestinal microbiota further facilitates CRC cell proliferation, invasion and metastasis and leads to therapy resistance. Hence, to target the dysregulated tumor metabolism, the TME and the gut microbiota, novel preventive and therapeutic applications are required. In this review, the dysregulation of metabolic programs, molecular pathways, the TME and the intestinal microbiota in CRC is addressed. Possible therapeutic strategies, including metabolic inhibition and immune therapy in CRC, as well as modulation of the aberrant intestinal microbiota, are discussed.

Immune System, Microbiota, and Microbial Metabolites: The Unresolved Triad in Colorectal Cancer Microenvironment

Colorectal cancer (CRC) is one of the most common cancers worldwide. As with other cancers, CRC is a multifactorial disease due to the combined effect of genetic and environmental factors. Most cases are sporadic, but a small proportion is hereditary, estimated at around 5-10%. In both, the tumor interacts with heterogeneous cell populations, such as endothelial, stromal, and immune cells, secreting different signals (cytokines, chemokines or growth factors) to generate a favorable tumor microenvironment for cancer cell invasion and metastasis. There is ample evidence that inflammatory processes have a role in carcinogenesis and tumor progression in CCR. Different profiles of cell activation of the tumor microenvironment can promote pro or anti-tumor pathways; hence they are studied as a key target for the control of cancer progression. Additionally, the intestinal mucosa is in close contact with a microorganism community, including bacteria, bacteriophages, viruses, archaea, and fungi composing the gut microbiota. Aberrant composition of this microbiota, together with alteration in the diet-derived microbial metabolites content (such as butyrate and polyamines) and environmental compounds has been related to CRC. Some bacteria, such as pks+ Escherichia coli or Fusobacterium nucleatum, are involved in colorectal carcinogenesis through different pathomechanisms including the induction of genetic mutations in epithelial cells and modulation of tumor microenvironment. Epithelial and immune cells from intestinal mucosa have Pattern-recognition receptors and G-protein coupled receptors (receptor of butyrate), suggesting that their activation can be regulated by intestinal microbiota and metabolites. In this review, we discuss how dynamics in the gut microbiota, their metabolites, and tumor microenvironment interplays in sporadic and hereditary CRC, modulating tumor progression.

Cloud-based archived metabolomics data: A resource for in-source fragmentation/annotation, meta-analysis and systems biology

Archived metabolomics data represent a broad resource for the scientific community. However, the absence of tools for the meta-analysis of heterogeneous data types makes it challenging to perform direct comparisons in a single and cohesive workflow. Here we present a framework for the meta-analysis of metabolic pathways and interpretation with proteomic and transcriptomic data. This framework facilitates the comparison of heterogeneous types of metabolomics data from online repositories (e.g., XCMS Online, Metabolomics Workbench, GNPS, and MetaboLights) representing tens of thousands of studies, as well as locally acquired data. As a proof of concept, we apply the workflow for the meta-analysis of i) independent colon cancer studies, further interpreted with proteomics and transcriptomics data, ii) multimodal data from Alzheimer's disease and mild cognitive impairment studies, demonstrating its high-throughput capability for the systems level interpretation of metabolic pathways. Moreover, the platform has been modified for improved knowledge dissemination through a collaboration with Metabolomics Workbench and LIPID MAPS. We envision that this meta-analysis tool will help overcome the primary bottleneck in analyzing diverse datasets and facilitate the full exploitation of archival metabolomics data for addressing a broad array of questions in metabolism research and systems biology.

Polyamines - A New Metabolic Switch: Crosstalk With Networks Involving Senescence, Crop Improvement, and Mammalian Cancer Therapy

Polyamines (PAs) are low molecular weight organic cations comprising biogenic amines that play multiple roles in plant growth and senescence. PA metabolism was found to play a central role in metabolic and genetic reprogramming during dark-induced barley leaf senescence (DILS). Robust PA catabolism can impact the rate of senescence progression in plants. We opine that deciphering senescence-dependent polyamine-mediated multidirectional metabolic crosstalks is important to understand regulation and involvement of PAs in plant death and re-mobilization of nutrients during senescence. This will involve optimizing the use of PA biosynthesis inhibitors, robust transgenic approaches to modulate PA biosynthetic and catabolic genes, and developing novel germplasm enriched in pro- and anti-senescence traits to ensure sustained crop productivity. PA-mediated delay of senescence can extend the photosynthesis capacity, thereby increasing grain starch content in malting grains such as barley. On the other hand, accelerating the onset of senescence can lead to increases in mineral and nitrogen content in grains for animal feed. Unraveling the "polyamine metabolic switch" and delineating the roles of PAs in senescence should further our knowledge about autophagy mechanisms involved in plant senescence as well as mammalian systems. It is noteworthy that inhibitors of PA biosynthesis block cell viability in animal model systems (cell tumor lines) to control some cancers, in this instance, proliferative cancer cells were led toward cell death. Likewise, PA conjugates work as signal carriers for slow release of regulatory molecule nitric oxide in the targeted cells. Taken together, these and other outcomes provide examples for developing novel therapeutics for human health wellness as well as developing plant resistance/tolerance to stress stimuli.

The biogenic amines putrescine and cadaverine show in vitro cytotoxicity at concentrations that can be found in foods

Putrescine and cadaverine are among the most common biogenic amines (BA) in foods, but it is advisable that their accumulation be avoided. Present knowledge about their toxicity is, however, limited; further research is needed if qualitative and quantitative risk assessments for foods are to be conducted. The present work describes a real-time analysis of the cytotoxicity of putrescine and cadaverine on intestinal cell cultures. Both BA were cytotoxic at concentrations found in BA-rich foods, although the cytotoxicity threshold for cadaverine was twice that of putrescine. Their mode of cytotoxic action was similar, with both BA causing cell necrosis; they did not induce apoptosis. The present results may help in establishing legal limits for both putrescine and cadaverine in food.

Self-Assembled Nanomedicines for Anticancer and Antibacterial Applications

Self-assembly strategies have been widely applied in the nanomedicine field, which provide a convenient approach for building various structures for delivery carriers. When cooperating with biomolecules, self-assembly systems have significant influence on the cell activity and life process and could be used for regulating nanodrug activity. In this review, self-assembled nanomedicines are introduced, including materials, encapsulation, and releasing strategies, where self-assembly strategies are involved. Furthermore, as a promising and emerging area for nanomedicine, in situ self-assembly of anticancer drugs and supramolecular antibiotic switches is also discussed about how to regulate drug activity. Selective pericellular assembly can block mass transformation of cancer cells inducing cell apoptosis, and the intracellular assembly can either cause cell death or effectively avoid drug elimination from cytosol of cancer cells because of the assembly-induced retention (AIR) effect. Host-guest interactions of drug and competitive molecules offer reversible regulations of antibiotic activity, which can reduce drug-resistance and inhibit the generation of drug-resistant bacteria. Finally, the challenges and development trend in the field are discussed.

Curcumin mediates polyamine metabolism and sensitizes gastrointestinal cancer cells to antitumor polyamine-targeted therapies

Curcumin, a natural polyphenol that contributes to the flavor and yellow pigment of the spice turmeric, is known for its antioxidant, anti-inflammatory, and anticarcinogenic properties. Capable of affecting the initiation, promotion, and progression of carcinogenesis through multiple mechanisms, curcumin has potential utility for both chemoprevention and chemotherapy. Previous studies demonstrated that curcumin can inhibit ornithine decarboxylase (ODC) activity in human leukemia and breast cancer cells, and pretreatment with dietary curcumin blocks carcinogen-induced ODC activity in rodent models of skin, colon, and renal cancer. The current study investigated the regulation of polyamine metabolism in human gastric and colon carcinoma cell lines in response to curcumin. Curcumin treatment significantly induced spermine oxidase (SMOX) mRNA and activity, which results in the generation of hydrogen peroxide, a source of ROS. Simultaneously, curcumin down regulated spermidine/spermine N1-acetyltransferase (SSAT) activity and the biosynthetic enzymes ODC and S-adenosylmethionine decarboxylase (SAMDC), thereby diminishing intracellular polyamine pools. Combination treatments using curcumin with the ODC inhibitor 2-difluoromethylornithine (DFMO), an agent currently in clinical chemoprevention trials, significantly enhanced inhibition of ODC activity and decreased growth of GI cancer cell lines beyond that observed with either agent alone. Similarly, combining curcumin with the polyamine analogue bis(ethyl)norspermine enhanced growth inhibition that was accompanied by enhanced accumulation of the analogue and decreased intracellular polyamine levels beyond those observed with either agent alone. Importantly, cotreatment with curcumin permitted the lowering of the effective dose of ODC inhibitor or polyamine analogue. These studies provide insight into the polyamine-related mechanisms involved in the cancer cell response to curcumin and its potential as a chemopreventive or chemotherapeutic agent in the GI tract.

Spermine and spermidine are cytotoxic towards intestinal cell cultures, but are they a health hazard at concentrations found in foods?

Spermine and spermidine are polyamines (PA) naturally present in all organisms, in which they have important physiological functions. However, an excess of PA has been associated with health risks. PA accumulates at quite high concentrations in some foods, but a quantitative assessment of the risk they pose has been lacking. In the present work, the cytotoxicity of spermine and spermidine was evaluated using an in vitro human intestinal cell model, and employing real-time cell analysis. Both spermine and spermidine showed a dose-dependent cytotoxic effect towards the cultured cells, with necrosis the mode of action of spermidine and perhaps also that of spermine. Spermine was more cytotoxic than spermidine, but for both PA the concentrations found to be toxic were above the maximum at which they have been found in food. The present results do not, therefore, support the idea that spermine or spermidine in food is harmful to healthy people.

Autonomous Multimodal Metabolomics Data Integration for Comprehensive Pathway Analysis and Systems Biology

Comprehensive metabolomic data can be achieved using multiple orthogonal separation and mass spectrometry (MS) analytical techniques. However, drawing biologically relevant conclusions from this data and combining it with additional layers of information collected by other omic technologies present a significant bioinformatic challenge. To address this, a data processing approach was designed to automate the comprehensive prediction of dysregulated metabolic pathways/networks from multiple data sources. The platform autonomously integrates multiple MS-based metabolomics data types without constraints due to different sample preparation/extraction, chromatographic separation, or MS detection method. This multimodal analysis streamlines the extraction of biological information from the metabolomics data as well as the contextualization within proteomics and transcriptomics data sets. As a proof of concept, this multimodal analysis approach was applied to a colorectal cancer (CRC) study, in which complementary liquid chromatography-mass spectrometry (LC-MS) data were combined with proteomic and transcriptomic data. Our approach provided a highly resolved overview of colon cancer metabolic dysregulation, with an average 17% increase of detected dysregulated metabolites per pathway and an increase in metabolic pathway prediction confidence. Moreover, 95% of the altered metabolic pathways matched with the dysregulated genes and proteins, providing additional validation at a systems level. The analysis platform is currently available via the XCMS Online ( XCMSOnline.scripps.edu ).

Polyamines: Bio-Molecules with Diverse Functions in Plant and Human Health and Disease

Biogenic amines-polyamines (PAs), particularly putrescine, spermidine and spermine are ubiquitous in all living cells. Their indispensable roles in many biochemical and physiological processes are becoming commonly known, including promoters of plant life and differential roles in human health and disease. PAs positively impact cellular functions in plants-exemplified by increasing longevity, reviving physiological memory, enhancing carbon and nitrogen resource allocation/signaling, as well as in plant development and responses to extreme environments. Thus, one or more PAs are commonly found in genomic and metabolomics studies using plants, particulary during different abiotic stresses. In humans, a general decline in PA levels with aging occurs parallel with some human health disorders. Also, high PA dose is detrimental to patients suffering from cancer, aging, innate immunity and cognitive impairment during Alzheimer and Parkinson diseases. A dichotomy exists in that while PAs may increase longevity and reduce some age-associated cardiovascular diseases, in disease conditions involving higher cellular proliferation, their intake has negative consequences. Thus, it is essential that PA levels be rigorously quantified in edible plant sources as well as in dietary meats. Such a database can be a guide for medical experts in order to recommend which foods/meats a patient may consume and which ones to avoid. Accordingly, designing both high and low polyamine diets for human consumption are in vogue, particularly in medical conditions where PA intake may be detrimental, for instance, cancer patients. In this review, literature data has been collated for the levels of the three main PAs, putrescine, spermidine and spermine, in different edible sources-vegetables, fruits, cereals, nuts, meat, sea food, cheese, milk, and eggs. Based on our analysis of vast literature, the effects of PAs in human/animal health fall into two broad, Yang and Yin, categories: beneficial for the physiological processes in healthy cells and detrimental under pathological conditions.

Regulation of Polyamine Metabolism by Curcumin for Cancer Prevention and Therapy

Curcumin (diferuloylmethane), the natural polyphenol responsible for the characteristic yellow pigment of the spice turmeric (Curcuma longa), is traditionally known for its antioxidant, anti-inflammatory, and anticarcinogenic properties. Capable of affecting the initiation, promotion, and progression of carcinogenesis through multiple mechanisms, curcumin has potential utility for both chemoprevention and chemotherapy. In human cancer cell lines, curcumin has been shown to decrease ornithine decarboxylase (ODC) activity, a rate-limiting enzyme in polyamine biosynthesis that is frequently upregulated in cancer and other rapidly proliferating tissues. Numerous studies have demonstrated that pretreatment with curcumin can abrogate carcinogen-induced ODC activity and tumor development in rodent tumorigenesis models targeting various organs. This review summarizes the results of curcumin exposure with regard to the modulation of polyamine metabolism and discusses the potential utility of this natural compound in conjunction with the exploitation of dysregulated polyamine metabolism in chemopreventive and chemotherapeutic settings.

Biogenic Amines in Dairy Products: Origin, Incidence, and Control Means

Biogenic amines (BAs) are toxic compounds produced by a number of microorganisms (bacteria, yeasts, and molds) as a result of the metabolism of some amino acid, usually decarboxylation reactions. BA-producing microorganisms are not necessarily pathogenic, such as lactic acid bacteria, which are, on the contrary, among the most beneficial microbiota to human beings and some of which even have probiotic properties. However, the incidence of BAs in dairy products and their possible implication in serious dairy-borne intoxications has long been overlooked. Consequently, the implementation of control measures to limit such an incidence has not been considered among the priorities of the food safety authorities. Nonetheless, there is a growing concern with regard to the presence of BAs in dairy products, because their toxicological status as toxins that may have serious acute and/or chronic adverse health effects is becoming increasingly evident and well-documented. The main BAs associated with dairy products are reviewed herein from the perspective of their incidence in these food products, and to draw the attention of readers to the shortage in data to perform pertinent risk assessment, which is considered to be a key action to provide efficient control means and to help decision makers issue appropriate legislative and regulatory measures.

Biologically active amines in fermented and non-fermented commercial soybean products from the Spanish market

Biologically active amines were determined in commercial soybean products. The antioxidant polyamines were found in both non-fermented and fermented soybean products. Natto and tempeh showed the highest content of polyamines (75-124 and 11-24 mg/kg of spermidine and spermine, respectively). On the other hand, the bacterial-related biogenic amines, tyramine, histamine, tryptamine and β-phenylethylamine, were detected in practically all fermented products with a high variability. The highest contents were found in sufu, tamari and soybean paste. Extremely high tyramine and histamine contents, 1700 and 700 mg/kg, respectively, found in some sufu samples could be unhealthy. However, biogenic amines observed in the other soybean products should not be a risk for healthy consumers. However, individuals who take monoamine and diamine oxidase inhibitors drugs should be strongly recommended to avoid this kind of products in order to suffer no adverse health effects. These biogenic amines were not detected in non-fermented soybean products.

Dietary polyamine intake and polyamines measured in urine

Dietary polyamines have recently been associated with increased risk of pre-malignant colorectal lesions. Because polyamines are synthesized in cells and taken up from dietary sources, development of a biomarker of exposure is challenging. Excess polyamines are primarily excreted in the urine. This pilot study seeks to identify dietary correlates of excreted urinary polyamines as putative biomarkers of exposure. Dietary polyamines/other nutrients were estimated from a food frequency questionnaire (FFQ) and correlated with urinary levels of acetylated polyamines in 36 men using 24-h urine samples. Polyamines, abundant in cheese and citrus, were highly positively correlated with urinary N(8)-acetylspermidine (correlation coefficient; r = 0.37, P = 0.03), but this correlation was attenuated after adjustment for total energy intake (r = 0.07, P = 0.68). Dietary energy intake itself was positively correlated with urinary total acetylated polyamine output (r = .40, P = 0.02). In energy-adjusted analyses, folic acid and folate from food were associated with urinary N(1),N(12)-diacetylspermine (r = 0.34, P = 0.05 and r = -0.39, P = 0.02, respectively). Red meat negatively correlated with total urinary acetylated polyamines (r = -0.42, P = 0.01). Our findings suggest that energy, folate, folic acid, saturated fat, and red meat intake, as opposed to FFQ-estimated dietary polyamines, are correlated with urinary polyamines.

Use of defatted flaxseed meal reduces precancerous colon lesions in C57BL/6 mice

PURPOSE

To investigate the hemopreventive effect of defatted flaxseed meal in C57BL/6 mice after induction of precancerous colon lesions with 1.2-dimethylhydrazine (DMH).

METHODS

Thirty-six 12-week-old C57BL/6 mice were divided into three treatment groups(n=12 in each group): (1) diet with 10% defatted flaxseed meal; (2) diet with defatted flaxseed meal and precancerous colon lesions induced by DMH; and (3) precancerous colon lesions induced by DMH, without defatted flaxseed meal. The incidence of aberrant crypt foci (ACF), oxidative processes, expression of tumor suppressor proteins and cyclins, as well as the profile of short-chain fatty acids (SCFA) in animal feces were investigated in the presence and absence of DMH.

RESULTS

The rats consuming defatted flaxseed meals showed lesions with lower multiplicity and a reduced incidence of lesions. No changes in the expression of tumor suppressor proteins and those involved in cell cycle control were detected.

CONCLUSION

Defatted flaxseed meal protected the distal colon of mice from precancerous lesions.

Polyamine pathway inhibition as a novel therapeutic approach to treating neuroblastoma

Polyamines are highly regulated essential cations that are elevated in rapidly proliferating tissues, including diverse cancers. Expression analyses in neuroblastomas suggest that up-regulation of polyamine pro-synthetic enzymes and down-regulation of catabolic enzymes is associated with poor prognosis. Polyamine sufficiency may be required for MYCN oncogenicity in MYCN amplified neuroblastoma, and targeting polyamine homeostasis may therefore provide an attractive therapeutic approach. ODC1, an oncogenic MYCN target, is rate-limiting for polyamine synthesis, and is overexpressed in many cancers including neuroblastoma. Inhibition of ODC1 by difluoromethylornithine (DFMO) decreased tumor penetrance in TH-MYCN mice treated pre-emptively, and extended survival and synergized with chemotherapy in treating established tumors in both TH-MYCN and xenograft models. Efforts to augment DFMO activity, or otherwise maximally reduce polyamine levels, are focused on antagonizing polyamine uptake or augmenting polyamine export or catabolism. Since polyamine inhibition appears to be clinically well tolerated, these approaches, particularly when combined with chemotherapy, have great potential for improving neuroblastoma outcome in both MYCN amplified and non-MYCN amplified neuroblastomas.

Short curcumin treatment modulates oxidative stress, arginase activity, aberrant crypt foci, and TGF-β1 and HES-1 transcripts in 1,2-dimethylhydrazine-colon carcinogenesis in mice

This study investigated the effect of short curcumin treatment, a natural antioxidant on 1,2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) in mice. The incidence of aberrant crypt foci (ACF) was 100%, with 54 ± 6 per colon, 10 weeks after the first DMH injection and reached 67 ± 12 per colon after 12 weeks. A high level of undifferentiated goblet cells and a weak apoptotic activity were shown in dysplastic ACF. The morphological alterations of colonic mucosa were associated to severe oxidative stress ratio with 43% increase in malondialdehyde vs. 36% decrease in GSH. DMH also increased inducible nitric synthase (iNOS) mRNA transcripts (250%), nitrites level (240%) and arginase activity (296%), leading to nitrosative stress and cell proliferation. Curcumin treatment, starting at week 10 post-DMH injection for 14 days, reduced the number of ACF (40%), iNOS expression (25%) and arginase activity (73%), and improved redox status by approximately 46%, compared to DMH-treated mice. Moreover, curcumin induced apoptosis of dysplastic ACF cells without restoring goblet cells differentiation. Interestingly, curcumin induced a parallel increase in TGF-β1 and HES-1 transcripts (42% and 26%, respectively). In conclusion, the protective effect of curcumin was driven by the reduction of arginase activity and nitrosative stress. The up regulation of TGF-β1 and HES-1 expression by curcumin suggests for the first time, a potential interplay between these signalling pathways in the chemoprotective mechanism of curcumin.

COX-2-independent induction of apoptosis by celecoxib and polyamine naphthalimide conjugate mediated by polyamine depression in colorectal cancer cell lines

BACKGROUND

Polyamine metabolism is an intriguing tumor therapeutic target. The present study was designed to assess the synergistic antitumor effects of NPC-16, a novel polyamine naphthalimide conjugate, with celecoxib and to elucidate the mechanism of these effects on human colorectal cancer cells.

METHODS

Cell proliferation was assessed by the MTT assay. Cell apoptosis and mitochondria membrane potential were evaluated by high content screening analysis. Intracellular polyamine content was detected by HPLC. Protein expression was detected by western blot analysis.

RESULTS

The co-treatment with celecoxib enhanced NPC-16-induced apoptosis in HCT116 (COX-2 no expression), HT29 (COX-2 higher expression) and Caco-2 (COX-2 higher expression) colorectal cancer cells, which was mediated by the elevated NPC-16 uptake via the effect of celecoxib on polyamine metabolism, including the up-regulated spermidine/spermine N(1)-acetyltransferase (SSAT) activity and reduced intracellular polyamine levels. The presence of celecoxib does not result in obviously different effect on the NPC-16-triggered apoptosis in diverse COX-2 expressed colorectal cell lines, suggesting that COX-2 was not one vital factor in the apoptotic mechanism. Furthermore, this synergistic apoptosis was involved in the PKB/AKT signal pathway, Bcl-2 and caspase family members. Z-VAD-FMK, a cell permeable pan caspase inhibitor, almost completely inhibited celecoxib and NPC-16 co-induced apoptosis, indicating that this apoptosis was caspase dependent.

CONCLUSIONS

Co-treatment of celecoxib and NPC-16 could induce colorectal cancer cell apoptosis via COX-2-independent and caspase-dependent mechanisms. The combination therapy with these agents might provide a novel therapeutic model for colorectal cancer.

Fish oil improves the lipid profile and reduces inflammatory cytokines in Wistar rats with precancerous colon lesions

A fatty diet is regarded as one of the most important risk factors related to the etiology of colorectal cancer, and this effect is linked to the quantity and principal types of fatty acids consumed. In this study, the chemopreventive effects of different oils on rats were investigated. Forty Wistar rats received 1,2-dimetilhidrazine (DMH) and were divided into 4 groups fed normal lipid diets to which 4% olive, fish, flaxseed, or soybean oils (control) were added. The group fed with fish oil presented higher levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid in hepatic tissue and greater levels of linolenic acid and EPA in adipose tissue compared to the other treatments. In the proximal portion of the colon, lower levels of aberrant crypt foci were found in the fish and flaxseed oil groups; however, this behavior was not observed in the middle and distal regions. Via a benchmarking method, the fish oil group showed a greater transforming growth factor β expression and lower interleukin-8 expression in relation to the other treatments. Fish oil in a normal lipid diet demonstrated a limited protective effect on the colonic precancerous mucosa in carcinogen-treated rodents, whereas it had a beneficial effect on inflammatory modulation.

Sodium butyrate does not decrease the evolution of precancerous lesions in rats

PURPOSE

To evaluate the preventive effect of sodium butyrate in the appearance of aberrant crypt foci (ACF) in rats after induction with the carcinogen 1,2-dimethylhydrazine (DMH).

METHODS

Forty Wistar rats were separated into four groups (n=10) distributed as follows: control 1, control 2, butyrate 1 and butyrate 2. The groups control 1 and butyrate 1 remained under experimentation for 4 weeks, while the groups control 2 and butyrate 2 remained for 8 weeks. In the first four weeks, the animals of the control groups received water ad libitum and the animals of the butyrate groups received a sodium butyrate solution (3.4%) ad libitum. Injections of the drug 1,2-dimethylhydrazine were applied during the two first weeks of the experiment in all the animals, concurrently with the application of sodium butyrate. The large intestine of the animals was removed, for the analysis of the ACF and of the content of polyamines. The animal feces were collected for the analysis of the SCFA profile.

RESULTS

The spermidine presented a higher concentration in the group butyrate 2 in comparison to the group control 2. There was a significant difference in the concentration value (µmol/mL) of acetate in comparison to the groups control 2 and butyrate 2.

CONCLUSION

The use of sodium butyrate together with the induction of colorectal cancer was not effective in the prevention of the disease progression.

DFMO: targeted risk reduction therapy for colorectal neoplasia

Strategies to decrease intracellular polyamine levels have been studied for their efficacy in reducing colorectal cancer (CRC) risk. A successful strategy combined agents that decreased polyamine synthesis by inhibiting ornithine decarboxylase with difluoromethylornithine (DFMO), and increased cellular export of polyamines by activating the spermidine/spermine acetyl transferase with non-steroidal anti-inflammatory drugs (NSAIDs). A Phase III trial treating resected adenoma patients with DFMO plus sulindac demonstrated marked reduction of metachronous adenomas, advanced adenomas and multiple adenomas compared to placebo. This combination regimen was well-tolerated, however there was a non-significant excess of cardiovascular events in the treatment arm compared to placebo as well as modest ototoxicity. Targeting this therapy to people at elevated risk of CRC, and employing clinical and genetic predictors, should improve patient benefit and reduce the risk of side effects to improve the acceptability of this strategy.

Adenovirus-mediated expression of SSAT inhibits colorectal cancer cell growth in vitro

AIM

To construct a recombinant adenovirus that can express human spermidine/ spermine N1-acetyltransferase (SSAT) and detect its inhibitory effect on colorectal cancer cell growth in vitro.

METHODS

A 516 bp cDNA of SSAT was amplified and cloned into a pGL3-hTERT plasmid. The pGL3-hTERT-SSAT recombinant was digested, and the small fragment was cloned into the shuttle vector pAdTrack. The pAdTrack-hTERT-SSAT plasmids were recombined with pAdEasy-1 vectors in AdEasy-1 cells. Positive clones were selected and transfected into the HEK293 packaging cells (transformed human embryonic kidney cells) after they were linearized by PacI. The process of adenovirus packaging and amplification was monitored by green fluorescent protein (GFP) expression. The SSAT protein levels were determined by Western blotting, and the intracellular polyamine content was detected by reverse-phase high performance liquid chromatography. The MTS (3-(4, 5-dimethylthiaol-2-yl)-5-(3-carboxy-methoxyphenyl)-2-(-4- sulfophenyl)-2H-tetrazolium, inner salt) and colony-forming assays were used to analyze the gene transduction efficiency and effect on the growth of HT-29 and LoVo cells. A viable cell count was used to determine the cell growth with or without exogenous polyamines.

RESULTS

The GFP expression in 293 cells during virus packing and amplification was observed by fluorescence microscopy. Western blotting results demonstrated that Ad-hTERT-SSAT could increase the expression of SSAT, and consequently, spermidine and spermine were reduced to low levels. The MTS and colony-forming assay results showed that HT-29 and LoVo cell growth were significantly inhibited, and the inhibitory effect could be partially reversed by exogenous spermidine and spermine.

CONCLUSION

The successfully constructed recombinant adenovirus Ad-hTERT-SSAT could accelerate polyamine catabolism and inhibit the colorectal cell growth in vitro. It also has therapeutic potential in the treatment of colorectal cancer.

Polyamines and the intestinal tract

Owing to their high turnover, the intestinal mucosal cells have a particularly high requirement for polyamines. Therefore, they are an excellent charcol for the study of polyamine function in rapid physiological growth and differentiation. After a cursory introduction to the major aspects of polyamine metabolism, regulation, and mode of action, we discuss the contribution of the polyamines to the maintenance of normal gut function, the maturation of the intestinal mucosa, and its repair after injuries. Repletion of cellular polyamine pools with (D,L)-2-(difluoromethyl)ornithine has considerably improved our understanding of how the polyamines are involved in the regulation of normal and neoplastic growth. Unfortunately, the attempts to exploit polyamine metabolism as a cancer therapeutic target have not yet been successful. However, the selective inactivation of ornithine decarboxylase appears to be a promising chemopreventive method in familial adenomatous polyposis. Presumably, it relies on the fact that ornithine decarboxylase is a critical regulator of the proliferative response of the protooncogene c-myc, but not of its apoptotic response.

Polyamine metabolism and tumorigenesis in the Apc(Min/+) mouse

While polyamine homoeostasis is clearly important in maintenance of normal cell function, the roles of these cations, as well as the enzymes that regulate their metabolism, in the neoplastic process are not clear. In particular, the polyamine catabolic enzyme SSAT (spermidine/spermine N(1)-acetyltransferase) seems to have different roles in tumorigenesis, depending upon the particular system being analysed. In attempts to clarify the function of SSAT in tumour development, we have utilized the Apc(Min/+) mouse, which carries a mutant allele of the Apc (adenomatous polyposis coli) gene, rendering it susceptible to the formation of multiple adenomas in the small intestine and colon. Using genetically engineered animals (i.e. transgenic and knockout mice), we have shown that SSAT acts as a tumour promoter in the Apc(Min/+) model. Modulation of tumorigenesis is not associated with changes in tissue levels of either spermidine or spermine. These findings, along with those made in other animal models of cancer, have prompted us to propose that metabolic flux through the polyamine biosynthetic and catabolic pathways, and the consequent changes in levels of various metabolites within the cell (i.e. the metabolome), is critical to tumour development. The metabolic flux model represents a novel way of thinking about the role of polyamines in cell physiology and the neoplastic process.

Effect of vasoactive intestinal peptide on gastric adenocarcinoma

BACKGROUND AND AIM

Vasoactive intestinal peptide (VIP) is a gastrointestinal hormone in the secretin-VIP family. It has been reported that VIP affects some tumor growth, and there is a VIP autocrine regulation in some cancers. However, the effect of VIP on gastric adenocarcinoma is not clear yet. The aim of the present study was to investigate the effect of VIP on gastric adenocarcinoma, especially autocrine regulation of VIP on gastric adenocarcinoma.

METHODS

VIP mRNA and protein, and its receptor mRNA (VIPR(1) and VIPR(2)) were measured in 15 normal antrum mucosa, 20 gastric adenocarcinoma tissues, and the SGC7901 gastric adenocarcinoma cell line by using reverse transcription polymerase chain reaction (RT-PCR), immunohistochemistry, or radioimmunoassay methods. The effect of the VIP protein and its antagonist (D-p-Cl-Phe6, Leu17)-VIP on SGC7901 cell growth was detected by methylthiazolyldiphenyl-tetrazolium bromide (MTT) method. The expressions of c-myc mRNA and ornithine decarboxylase (ODC) mRNA in SGC7901 cells before and after the incubated VIP protein and/or its antagonist were also measured by RT-PCR method.

RESULTS

The VIP mRNA expression in gastric adenocarcinoma tissues was significantly higher than that in normal antrum mucosa (P < 0.01). The VIP-positive immunoreactivity cells existed in 40% of gastric adenocarcinoma tissues, but not in normal tissues (P < 0.01). The VIP-positive immunoreactivity nerve fibers were observed in normal tissues, but not in adenocarcinoma tissues (P < 0.01). The expression rate of VIPR(1) mRNA in adenocarcinoma tissues was significantly lower than that in normal tissues, but that of VIPR(2) mRNA in the two kinds of tissues were similar (P > 0.05). In addition, the expression quantity of VIPR(1) mRNA and VIPR(2) mRNA in adenocarcinoma tissues was significantly lower than that in normal tissues (P < 0.05). SGC7901 cells expressed not only VIP mRNA and the VIP protein, but also VIPR(1) and VIPR(2) mRNA. 10(6) SGC7901 cells secreted 13.15 +/- 8.54 pg VIP on average. VIP did not affect the proliferation of SGC7901 cells, but the antagonist stimulated the proliferation of SGC7901 cells from 10(-5) to 10(-8) mol/L concentration incubated for 24-96 h. VIP downregulated the expressions of c-myc and ODC mRNA, but its antagonist upregulated their expressions.

CONCLUSIONS

The expression of VIP mRNA upregulates, but the expressions of VIPR mRNA downregulates in gastric adenocarcinoma tissues. The gastric adenocarcinoma tissues contain endocrine cells to secrete VIP, which show malignant specialities. The VIP autocrine regulation exists in SGC7901 cells, and potentially inhibits the proliferation of the cells by downregulating the expressions of c-myc and ODC mRNA. It suggests that VIP may play an important role in the regulation of the growth of gastric cancer cells.

Dietary putrescine reduces the intestinal anticarcinogenic activity of sulindac in a murine model of familial adenomatous polyposis

The nonsteroidal antiinflammatory drug sulindac displays chemopreventive activity in patients with familial adenomatous polyposis (FAP). Sulindac metabolites induce apoptosis in colon tumor cells, in part, by a polyamine-dependent mechanism that can be suppressed with exogenous putrescine. To determine the relevance of this mechanism in animals, we treated Apc(Min/+) mice, a model of human FAP, with sulindac alone or in combination with dietary putrescine. Sulindac increased steady-state RNA levels and enzymatic activity of the polyamine catabolic enzyme spermidine/spermine N(1)-acetyltransferase and intestinal levels of monoacetylspermidine, spermidine, and spermine in the small intestine of mice. Sulindac also decreased the activity of the biosynthetic enzyme ornithine decarboxylase but not adenosylmethionine decarboxylase (AMD). Dietary putrescine increased intestinal putrescine contents, whereas the combination of dietary putrescine and sulindac yielded the highest levels of intestinal putrescine and correlated with a statistically significant reduction in AMD enzyme activity. Dietary putrescine did not statistically significantly increase tumorigenesis, although it significantly increased the grade of adenoma dysplasia (P < 0.05). The effectiveness of sulindac to suppress intestinal carcinogenesis was partially abrogated by dietary putrescine. These data suggest that sulindac exerts at least some of its anticarcinogenic effects in mice via a polyamine-dependent mechanism. Because high concentrations of putrescine can be found in certain dietary components, it may be advantageous to restrict dietary putrescine consumption in patients undergoing treatment with sulindac.

Spermine and spermidine mediate protection against oxidative damage caused by hydrogen peroxide

The polyamines spermidine and spermine have been hypothesized to possess different functions in the protection of DNA from reactive oxygen species. The growth and survival of mouse fibroblasts unable to synthesize spermine were compared to their normal counterparts in their native and polyamine-depleted states in response to oxidative stress. The results of these studies suggest that when present at normal or supraphysiological concentrations, either spermidine or spermine can protect cells from reactive oxygen species. However, when polyamine pools are pharmacologically manipulated to produce cells with low levels of predominately spermine or spermidine, spermine appears to be more effective. Importantly, when cells are depleted of both glutathione and endogenous polyamines, they exhibit increased sensitivity to hydrogen peroxide as compared to glutathione depletion alone, suggesting that polyamines not only play a role in protecting cells from oxidative stress but this role is distinct from that played by glutathione.

Polyamine metabolism and cancer prevention

Colorectal cancer is one of a number of cancers that may be amenable to prevention. The NSAIDs (non-steroidal anti-inflammatory drugs) have been shown to be effective chemopreventative agents in humans, but their mechanism of action is not clear. The polyamines are cellular polycations that are essential for cell growth and are overproduced in cancer cells. It is our hypothesis that inhibition of polyamine metabolism is an integral part of the mechanism of cancer prevention mediated by NSAIDs.

The role of spermidine/spermine N1-acetyltransferase in determining response to chemotherapeutic agents in colorectal cancer cells

Polyamines have been shown to play a role in the growth and survival of several solid tumors, including colorectal cancer. We identified the polyamine catabolic enzyme spermidine/spermine N(1)-acetyltransferase (SSAT) as being one of the most highly inducible genes in two DNA microarray screens to identify novel determinants of response to chemotherapeutic agents in colorectal cancer. SSAT was shown to be inducible in response to 5-fluorouracil (5-FU) or oxaliplatin in parental and drug-resistant HCT116 cell lines. It was also shown that SSAT mRNA was up-regulated in response to 5-FU or oxaliplatin in a panel of six colorectal cancer cell lines. The polyamine analogue N(1),N(11)-diethylnorspermine (DENSpm) depletes polyamine pools and potently induces SSAT. We evaluated the effect of combining DENSpm with chemotherapeutic agents in HCT116 p53(+/+) cells and in HCT116 drug-resistant daughter cell lines. Western blot analyses showed that SSAT protein expression was dramatically enhanced when DENSpm was combined with oxaliplatin or 5-FU in HCT116 p53(+/+) cells. Using cell viability assays and flow cytometry, synergistic induction of cell death was observed following cotreatment of HCT116 p53(+/+) cells with DENSpm and each chemotherapeutic agent. Of note, this combined therapy increased the chemosensitivity of cells rendered resistant to each of these chemotherapeutic agents. Small interfering RNA-mediated down-regulation of SSAT resulted in loss of synergy between DENSpm and these agents. These results show that SSAT plays an important role in regulating cell death following combined cytotoxic drug and DENSpm treatment. Furthermore, DENSpm sensitizes both sensitive and resistant cells to chemotherapeutic agents. Taken together, these results suggest that SSAT may be an important target for therapeutic intervention in colorectal cancer.