Nutritional factors and polyamine metabolism in colorectal cancer

Anticancer effect of a combinatorial treatment of 5-fluorouracil and cell extract of some probiotic lactobacilli strains isolated from camel milk on colorectal cancer cells

Colorectal cancer (CRC) has the highest mortality rate among cancer types, emphasizing the need for auxiliaries to 5-fluorouracil (5-FU) due to resistance and side effects. Metabolites produced by probiotic bacteria exhibit promising anticancer properties against CRC. In the current study, the anticancer effects of cell extract of three potential probiotic lactobacilli strains isolated from camel milk, Lactobacillus helveticus, Lactobacillus gallinarum, and Lactiplantibacillus plantarum, as well as that of the standard probiotic strain Lacticaseibacillus rhamnosus GG (LGG), on the human colon cancer cell line (HT-29) and the normal HEK293 cell line separately or in combination with 5-FU, were evaluated. This study isolated strains from camel milk and compared their probiotic properties to those of LGG. The cell viability, cell apoptosis, and Th17 cytokine production were assessed using the MTT assay, acridine orange/ethidium bromide (AO/EB) staining, and flow cytometry techniques, respectively. The cell extracts of lactobacilli strains combined with 5-FU reduced HT-29 cell viability effectively and increased cell apoptosis. Nevertheless, the cell extracts of lactobacilli strains combined with 5-FU controlled the cytotoxic impact of 5-FU on HEK-293 cell viability and reduced cell apoptosis. No significant differences were observed among the strains. Moreover, the cell extracts from the strains combined with 5-FU increased the levels of cytokines IFN-γ, TNF-α, and IL-17A, all of which contribute to immunity against tumors. The performance of the studied strains was similar to that of the standard probiotic strain (LGG). The investigation revealed that cell extracts from lactobacilli strains may serve as a promising complementary anticancer treatment.

Multicopper Oxidase from Lactobacillus hilgardii: Mechanism of Degradation of Tyramine and Phenylethylamine in Fermented Food

Elevated levels of biogenic amines (BAs) in fermented food can have negative effects on both the flavor and health. Mining enzymes that degrade BAs is an effective strategy for controlling their content. The study screened a strain of Lactobacillus hilgardii 1614 from fermented food system that can degrade BAs. The multiple copper oxidase genes LHMCO1614 were successfully mined after the whole genome protein sequences of homologous strains were clustered and followed by homology modeling. The enzyme molecules can interact with BAs to stabilize composite structures for catalytic degradation, as shown by molecular docking results. Ingeniously, the kinetic data showed that purified LHMCO1614 was less sensitive to the substrate inhibition of tyramine and phenylethylamine. The degradation rates of tyramine and phenylethylamine in huangjiu (18% vol) after adding LHMCO1614 were 41.35 and 40.21%, respectively. Furthermore, LHMCO1614 demonstrated universality in degrading tyramine and phenylethylamine present in other fermented foods as well. HS-SPME-GC-MS analysis revealed that, except for aldehydes, the addition of enzyme treatment did not significantly alter the levels of major flavor compounds in enzymatically treated fermented foods (p > 0.05). This study presents an enzymatic approach for regulating tyramine and phenylethylamine levels in fermented foods with potential applications both targeted and universal.

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.

Polyamines: their significance for maintaining health and contributing to diseases

Polyamines are essential for the growth and proliferation of mammalian cells and are intimately involved in biological mechanisms such as DNA replication, RNA transcription, protein synthesis, and post-translational modification. These mechanisms regulate cellular proliferation, differentiation, programmed cell death, and the formation of tumors. Several studies have confirmed the positive effect of polyamines on the maintenance of health, while others have demonstrated that their activity may promote the occurrence and progression of diseases. This review examines a variety of topics, such as polyamine source and metabolism, including metabolism, transport, and the potential impact of polyamines on health and disease. In addition, a brief summary of the effects of oncogenes and signaling pathways on tumor polyamine metabolism is provided. Video Abstract.

Effects of Microbial Communities on Volatile Profiles and Biogenic Amines in Beef Jerky from Inner Mongolian Districts

Beef jerky is a traditional fermented meat product from Inner Mongolia, handcrafted by artisans. We investigated the bacteria of the microbial community, volatile flavor components, and biogenic amines of Inner Mongolia beef jerky via high-throughput sequencing, solid-phase microextraction with gas chromatography−mass spectrometry, and high-performance liquid chromatography, respectively. Thirty-three bacteria were identified, predominantly from the genera Pseudomonas (45.4%), Ralstonia (13.4%), and Acinetobacter (7.3%). Fifty-nine volatile flavor compounds and eight biogenic amines were detected. Based on Spearman’s correlation coefficient, 20 bacterial genera were significantly associated with the dominant volatile compounds in the beef jerky samples (p < 0.05). The results demonstrated that beef jerky may be toxic due to cadaverine, putrescine, and histamine; moreover, the amounts of putrescine and cadaverine were positively correlated with the abundance of unclassified_f_Enterobacteriaceae (p < 0.05). These findings shed light on the formation of the microbial community, flavor components, and biogenic amines of beef jerky, thereby providing a basis for improving its quality.

Polyamines: Functions, Metabolism, and Role in Human Disease Management

Putrescine, spermine, and spermidine are the important polyamines (PAs), found in all living organisms. PAs are formed by the decarboxylation of amino acids, and they facilitate cell growth and development via different cellular responses. PAs are the integrated part of the cellular and genetic metabolism and help in transcription, translation, signaling, and post-translational modifications. At the cellular level, PA concentration may influence the condition of various diseases in the body. For instance, a high PA level is detrimental to patients suffering from aging, cognitive impairment, and cancer. The levels of PAs decline with age in humans, which is associated with different health disorders. On the other hand, PAs reduce the risk of many cardiovascular diseases and increase longevity, when taken in an optimum quantity. Therefore, a controlled diet is an easy way to maintain the level of PAs in the body. Based on the nutritional intake of PAs, healthy cell functioning can be maintained. Moreover, several diseases can also be controlled to a higher extend via maintaining the metabolism of PAs. The present review discusses the types, important functions, and metabolism of PAs in humans. It also highlights the nutritional role of PAs in the prevention of various diseases.

Dietary Polyamines Intake and Risk of Colorectal Cancer: A Case-Control Study

Polyamines (including putrescine, spermidine, and spermine) are small, cationic molecules that are necessary for cell proliferation and differentiation. Few studies have examined the association of dietary polyamines intake with colorectal cancer risk. The aim of this study was to evaluate total polyamines, putrescine, spermidine, and spermine intake in relation to colorectal cancer risk in China. In total, 2502 colorectal cancer cases and 2538 age-(5-year interval) and sex-matched controls were recruited from July 2010 to April 2019. Odds ratios (ORs) and 95% confidence intervals (CI) were calculated by multivariable unconditional logistic regression after adjustment for various potential confounding factors. Higher intake of total polyamine, putrescine and spermidine was significantly associated with reduced risk of colorectal cancer. The adjusted ORs for the highest compared with the lowest quartile of intake were 0.60 (95% CI 0.50, 0.72; P_trend < 0.001) for total polyamines, 0.35 (95% CI 0.29, 0.43; P_trend < 0.001) for putrescine and 0.79 (95% CI 0.66, 0.95; P_trend = 0.001) for spermidine, respectively. However, higher intake of spermine was associated with increased risk of colorectal cancer, with an adjusted OR of 1.58 (95% CI 1.29, 1.93; P_trend < 0.001). This data indicate that higher intake of total polyamines, putrescine and spermidine, as well as lower intake of spermine, is associated with a decreased risk of colorectal cancer.

Dietary natural methylxanthines and colorectal cancer: a systematic review and meta-analysis

Some evidence suggests that caffeine, theophylline, and theobromine, as natural methylxanthines (MTXs), possess anti-cancer effects.

Biogenic Amines Formation Mechanism and Determination Strategies: Future Challenges and Limitations

The evolution in foodstuff-monitoring processes has increased the number of studies on biogenic amines (BAs), in recent years. This trend with future perspective needs to be assembled to address the associated health risks. Thus, this study aims to cover three main aspects of BAs: (i) occurrence, physiology, and toxicological effects, most probable formation mechanisms and factors controlling their growth; (ii) recent advances, strategies for determination, preconcentration steps, model technique, and nature of the matrix; and (iii) milestone, limitations with existing methodologies, future trends, and detailed expected developments for clinical use and on-site ultra-trace determination. The core of the ongoing review will discuss recent trends in pre-concentration toward miniaturization, automation, and possible coupling with electrochemical techniques, surface-enhanced Raman scattering, spectrofluorimetry, and lateral flow protocols to be exploited for the development of rapid, facile, and sensitive on-site determination strategies for BAs.

Anticancer and Antimigration Effects of a Combinatorial Treatment of 5-Fluorouracil and Lactobacillus paracasei subsp. paracasei NTU 101 Fermented Skim Milk Extracts on Colorectal Cancer Cells

Colorectal cancer (CRC) is one of the most prevalent cancers worldwide. Metabolites of lactic acid bacteria (LAB) have anticancer and antimetastasis capacities. This study aimed to investigate the chemotherapeutic effects of Lactobacillus paracasei subsp. paracasei NTU 101-fermented skim milk (NTU101-FM) extracts in combination with the chemotherapeutic drug 5-fluorouracil (5-FU) in a cellular CRC model. The NTU101-FM extracts effectively reduced CRC cell viability but were not cytotoxic to colon epithelial cells. Moreover, they increased RAW 264.7 cell viability. Notably, the cell viability of CRC cells was decreased by 5-FU in combination with the NTU101-FM extracts; the combinatorial treatment inhibited cell viability significantly more than 5-FU alone ( p < 0.05). An ethanol extract of NTU101-FM effectively attenuated CT26 cell migration. In conclusion, the ethanol extract prepared from NTU101-FM has a potential application as an anticancer agent in CRC.

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.

Consumption effect of a synbiotic beverage made from soy and yacon extracts containing Bifidobacterium animalis ssp. lactis BB-12 on the intestinal polyamine concentrations in elderly individuals

This study aimed to investigate the effect of a synbiotic beverage made from soy and yacon (Smallanthus sonchifolius) extracts containing Bifidobacterium animalis ssp. lactis BB-12 on healthy elderly individuals' intestinal polyamine concentrations. A randomized, double-blinded, placebo-controlled trial has been conducted with twenty-nine volunteers (over 65years of age) who either had a daily intake of 150mL of synbiotic (synbiotic group - S) or placebo (placebo group - P) beverages. Both had the same nutrient composition, except that a probiotic culture was added to the synbiotic beverage. Total experiment time was 8weeks, which was divided into 3 consecutive phases: a prefeeding period (2weeks), followed by a feeding period (4weeks) and a postfeeding period (2weeks). Stool samples were collected at 3 time periods. Fecal concentrations of polyamines, putrescine (PUT), cadaverine (CAD) and spermidine (SPD) that were obtained during the synbiotic and placebo consumption period were significantly higher (p<0.05) than those found during the pre-consumption baseline level period. No significant differences in the number of bifidobacteria, clostridia, or enterobacteria were observed in any of the two groups at the three time periods. Similarly, no significant effect on the production of proinflammatory cytokines tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and anti-inflammatory interleukin-10 (IL-10) was induced by the synbiotic or placebo beverages consumption. The results herein indicate that both the synbiotic and the placebo beverage consumption have increased polyamines levels, which are often reduced in elderly individuals, without influencing inflammatory responses. In addition, both placebo and synbiotic beverages seems to contribute by maintaining increased polyamines levels.

Anti-tumour immune effect of oral administration of Lactobacillus plantarum to CT26 tumour-bearing mice

Colorectal cancer (CRC) is one of the most prevalent forms of cancer that shows a high mortality and increasing incidence. There are numerous successful treatment options for CRC, including surgery, chemotherapy, radiotherapy and immunotherapy; however, their side effects and limitations are considerable. Probiotics may be an effective strategy for preventing and inhibiting tumour growth through stimulation of host innate and adaptive immunity. We investigated and compared potential anti-tumour immune responses induced by two isolated Lactobacillus strains, Lactobacillus plantarum A and Lactobacillus rhamnosus b, by pre-inoculating mice with lactobacilli for 14 days. Subsequently, subcutaneous and orthotopic intestinal tumours were generated in the pre-inoculated mice using CT26 murine adenocarcinoma cells and were assessed for response against the tumour. Our results indicated that oral administration with L. plantarum inhibited CT26 cell growth in BALB/c mice and prolonged the survival time of tumour-bearing mice compared with mice administered L. rhamnosus. L. plantarum produced protective immunity against the challenge with CT26 cells by increasing the effector functions of CD8+ and natural killer (NK) cell infiltration into tumour tissue, up-regulation of IFN-gamma (but not IL-4 or IL-17) production, and promotion of Th1-type CD4+ T differentiation. Consequently, our results suggest that L. plantarum can enhance the anti-tumour immune response and delay tumour formation.

AguR, a Transmembrane Transcription Activator of the Putrescine Biosynthesis Operon in Lactococcus lactis, Acts in Response to the Agmatine Concentration

Dairy industry fermentative processes mostly use Lactococcus lactis as a starter. However, some dairy L. lactis strains produce putrescine, a biogenic amine that raises food safety and spoilage concerns, via the agmatine deiminase (AGDI) pathway. The enzymatic activities responsible for putrescine biosynthesis in this bacterium are encoded by the AGDI gene cluster. The role of the catabolic genes aguB, aguD, aguA, and aguC has been studied, but knowledge regarding the role of aguR (the first gene in the cluster) remains limited. In the present work, aguR was found to be a very low level constitutively expressed gene that is essential for putrescine biosynthesis and is transcribed independently of the polycistronic mRNA encoding the catabolic genes (aguBDAC). In response to agmatine, AguR acts as a transcriptional activator of the aguB promoter (PaguB), which drives the transcription of the aguBDAC operon. Inverted sequences required for PaguB activity were identified by deletion analysis. Further work indicated that AguR is a transmembrane protein which might function as a one-component signal transduction system that senses the agmatine concentration of the medium and, accordingly, regulates the transcription of the aguBDAC operon through a C-terminal cytoplasmic DNA-binding domain typically found in LuxR-like proteins.

Vitamin K1 exerts antiproliferative effects and induces apoptosis in three differently graded human colon cancer cell lines

Vitamin K1 has been demonstrated as having anticancer potentiality mainly in liver cancer cells. Beyond the reported mechanisms of cancer inhibition (cell cycle arrest and induction of apoptosis), a possible control by vitamin K1 on molecules affecting cell growth could be hypothesized. In the literature, few (if any) data are available on its antitumor effects on colon cancer cells. Therefore, the aims of the study were to investigate in three differently graded human colon cancer cell lines (Caco-2, HT-29, and SW480) the effects of increasing concentrations of vitamin K1 (from 10 μM to 200 μM) administered up to 72 h on (1) cell proliferation, (2) apoptosis with the possible involvement of the MAPK pathway, and (3) polyamine biosynthesis. Vitamin K1 treatment caused a significant antiproliferative effect and induced apoptosis in all the cell lines, with the involvement of the MAPK pathway. A concomitant and significant decrease in the polyamine biosynthesis occurred. This is the first study demonstrating a significant polyamine decrease in addition to the antiproliferative and proapoptotic effects following vitamin K1 administration to colon cancer cell lines. Therapeutically, combinations of vitamin K1 with polyamine inhibitors and/or analogues may represent a suitable option for chemoprevention and/or treatment in future strategies for colorectal cancer management.

Prevention of oxaliplatin-induced peripheral neuropathy by a polyamine-reduced diet-NEUROXAPOL: protocol of a prospective, randomised, controlled, single-blind and monocentric trial

INTRODUCTION

Oxaliplatin remains the most widely used chemotherapeutic agent for treating advanced colorectal cancer but its efficacy is hampered by dose-limiting neurotoxicity manifested by a painful polyneuropathy. Oxaliplatin-induced peripheral neuropathy (OIPN) is characterised by acute and transient cold hyperaesthesia in the hours and days following oxaliplatin infusion (>90% of patients), but also by retarded chronic neuropathy due to the repetition of chemotherapy cycles (30-50% of patients). OIPN impairs the health-related quality of life (HRQOL) of patients and no preventive or curative strategies have as yet proven effective. A polyamine-reduced diet (PRD) has recently demonstrated its efficacy to prevent OIPN in animals without adverse effects.

METHODS AND ANALYSIS

The NEUROXAPOL trial is a prospective, randomised, controlled, single-blind, monocentric and interventional study. This trial is aimed at evaluating the efficacy and feasibility of a PRD compared to a normal polyamine containing diet to prevent OIPN in patients treated by oxaliplatin-based chemotherapy. Patients (n=40 per group) will be randomly assigned to receive either a PRD or a normal diet before and during the chemotherapy regimen. The main objectives are to improve the cold pain thresholds, neuropathic pain symptoms, comorbidities (anxiety and depression) and HRQOL of patients. The primary end point is the assessment of cold pain thresholds 2 weeks after the third cycle of chemotherapy. The secondary end points are the evaluation of thermal pain thresholds, the grade of neuropathy, neuropathic pain, symptoms of anxiety and depression and HRQOL, until the 12th cycle of chemotherapy.

ETHICS AND DISSEMINATION

The study was approved by an independent medical ethics committee 1 (CPP Sud Est 1, Saint Etienne, France) and registered by the competent French authority (ANSM, Saint Denis, France). The results will be disseminated in a peer-reviewed journal and presented at international congresses.

TRIAL REGISTRATION NUMBER

NCT01775449.

Induction of HT-29 cells apoptosis by lactobacilli isolated from fermented products

A total of 138 lactobacillus strains were obtained from the traditional fermented foods of minority nationalities or infant faeces, respectively. The lactobacillus strains were screened for anticancer effects and probiotic potential. The results showed that 10 strains exerted anti-proliferative activity and higher adhering capability on HT-29 cells. They were then screened for resistance to biological barriers (acid and bile salts), and the four most promising strains were selected. Further analysis revealed that the 4 strains (cell walls and cytoplasm extracts) displayed the high anti-proliferative activity and the large extent of DNA strand breakage in individual cells. Through the selected procedure, cell walls that were extracted from X12, M5 and K14 strains induced apoptosis in HT-29 cells. Further investigation confirmed that apoptosis-inducing ability of cell wall extracts was attributed to the breakdown of mitochondrial membrane potential, which is a known initiation of apoptotic mitochondrial pathway. Cell walls from X12, M5 and K14 strains, were determined to be less harmful to noncancerous Vero cells than to human colon cancer HT-29 cells. These findings suggested that X12, M5 and K14 strains opposing the ability to induce HT-29 cells apoptosis, and cell wall extracts were involved in this apoptosis induction.

Probiotics in colorectal cancer (CRC) with emphasis on mechanisms of action and current perspectives

Colorectal cancer (CRC) is the third most common form of cancer. Diverse therapies such as chemotherapy, immunotherapy and radiation have shown beneficial effects, but are limited because of their safety and toxicity. Probiotic formulations have shown great promise in CRC as preventive and early stage therapeutics. This review highlights the importance of a balanced intestinal microbiota and summarizes the recent developments in probiotics for treating CRC. Specifically, this report describes evidence of the role of probiotics in modulating the microbiota, in improving the physico-chemical conditions of the gut and in reducing oxidative stress. It also discusses the mechanisms of probiotics in inhibiting tumour progression, in producing anticancer compounds and in modulating the host immune response. Even though some of these effects were observed in several clinical trials, when probiotic formulations were used as a supplement to CRC therapies, the application of probiotics as biotherapeutics against CRC still needs further investigation.

Role of dietary polyamines in a phase III clinical trial of difluoromethylornithine (DFMO) and sulindac for prevention of sporadic colorectal adenomas

Background:

The polyamine-inhibitory regimen difluoromethylornithine (DFMO)+sulindac has marked efficacy in preventing metachronous colorectal adenomas. Polyamines are synthesised endogenously and obtained from dietary sources. Here we investigate dietary polyamine intake and outcomes in the DFMO+sulindac colorectal adenoma prevention trial.

Methods:

Dietary polyamine data were available for 188 of 267 patients completing the study. Total dietary polyamine content was derived by the sum of dietary putrescine, spermine and spermidine values and categorised into two groups: highest (>75–100%) vs the lower three quartiles (0–25, 25–50 and 50–75%). Baseline tissue polyamine concentration and ODC1 genotype were determined. Logistic regression models were used for risk estimation.

Results:

A significant interaction was detected between dietary polyamine group and treatment with regard to adenoma recurrence (P=0.012). Significant metachronous adenoma risk reduction was observed after DFMO+sulindac treatment in dietary polyamine quartiles 1–3 (risk ratio (RR) 0.19; 95% confidence interval (CI) 0.08–0.42; P<0.0001) but not in quartile 4 (RR 1.51; 95% CI 0.53–4.29; P=0.44). However, a lower number of events in the placebo group within dietary quartile 4 confound the aforementioned risk estimates.

Conclusion:

These preliminary findings reveal complex relationships between diet and therapeutic prevention, and they support further clinical trial-based investigations where the dietary intervention itself is controlled.

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.

Oral inoculation of probiotics Lactobacillus acidophilus NCFM suppresses tumour growth both in segmental orthotopic colon cancer and extra-intestinal tissue

Modulation of the cellular response by the administration of probiotic bacteria may be an effective strategy for preventing or inhibiting tumour growth. We orally pre-inoculated mice with probiotics Lactobacillus acidophilus NCFM (La) for 14 d. Subcutaneous dorsal-flank tumours and segmental orthotopic colon cancers were implanted into mice using CT-26 murine colon adenocarcinoma cells. On day 28 after tumour initiation, the lamina propria of the colon, mesenteric lymph nodes (MLN) and spleen were harvested and purified for flow cytometry and mRNA analyses. We demonstrated that La pre-inoculation reduced tumour volume growth by 50·3 %, compared with untreated mice at 28 d after tumour implants (2465·5 (SEM 1290·4) v. 4950·9 (SEM 1689·3) mm³, P<0·001). Inoculation with La reduced the severity of colonic carcinogenesis caused by CT-26 cells, such as level of colonic involvement and structural abnormality of epithelial/crypt damage. Moreover, La enhanced apoptosis of CT-26 cells both in dorsal-flank tumour and segmental orthotopic colon cancer, and the mean counts of apoptotic body were higher in mice pre-inoculated with La (P<0·05) compared with untreated mice. La pre-inoculation down-regulated the CXCR4 mRNA expressions in the colon, MLN and extra-intestinal tissue, compared with untreated mice (P<0·05). In addition, La pre-inoculation reduced the mean fluorescence index of MHC class I (H-2Dd, -Kd and -Ld) in flow cytometry analysis. Taken together, these findings suggest that probiotics La may play a role in attenuating tumour growth during CT-26 cell carcinogenesis. The down-regulated expression of CXCR4 mRNA and MHC class I, as well as increasing apoptosis in tumour tissue, indicated that La may be associated with modulating the cellular response triggered by colon carcinogenesis.

Isothiocyanate sulforaphane inhibits protooncogenic ornithine decarboxylase activity in colorectal cancer cells via induction of the TGF-β/Smad signaling pathway

SCOPE

The objective of this study was to elucidate molecular mechanisms behind the antitumor activities of the isothiocyanate sulforaphane (SFN) in colorectal cancer cells.

METHODS AND RESULTS

Cell growth was determined by BrdU incorporation and crystal violet staining. Protein levels were examined by Western blot analysis. Ornithine decarboxylase (ODC) activity was assayed radiometrically. Reverse transcriptase-PCR was used for measuring mRNA expression. For reporter gene assays plasmids were transfected into cells via lipofection and luciferase activity was measured luminometrically. Acetyl-histone H3 and H4 chromatin immunoprecipitation (ChIP) assays were performed followed by PCR with TGF-β-receptor II promoter specific primers. We could show that SFN-mediated cell growth inhibition closely correlates with a dose-dependent reduction of protein expression and enzymatic activity of ODC. This effect seems to be due to reduced protein levels and transactivation activity of transcription factor c-myc, a direct regulator of ODC expression, as a consequence of SFN-induced TGF-β/Smad signaling. The coherency of these results was further confirmed by using TGF-β receptor kinase inhibitor SB431542, which largely abolishes inhibitory effects of SFN on both, ODC activity and cell growth.

CONCLUSION

Since elevated ODC enzyme activity is associated with enhanced tumor development, SFN may be a dietary phytochemical with potential to prevent carcinogenesis.

A central role for polyamines in microtubule assembly in cells

Owing to preferential electrostatic adsorption of multivalent cations on highly anionic surfaces, natural multivalent polyamines and especially quadrivalent spermine can be considered as potential regulators of the complex dynamical properties of anionic MTs (microtubules). Indeed, the C-terminal tails of tubulin display many negative residues in a row which should enable the formation of a correlated liquid-like phase of multivalent counterions on its surface. Although it is known that polyamine counterions promote MT assembly in vitro, little is known about the relevance of this interaction in vivo. In the present study, we have explored the relationship between polyamine levels and MT assembly in HeLa and epithelial NRK (normal rat kidney) cells using DFMO (α-difluoromethylornithine), an irreversible inhibitor of ornithine decarboxylase, and APCHA [N-(3-aminopropyl)-N-cyclohexylamine], a spermine synthase inhibitor. Under conditions of intracellular polyamine depletion, the MT network is clearly disrupted and the MT mass decreases. Addition of spermine to polyamine-depleted cells reverses this phenotype and rapidly promotes the extensions of the MT network. Finally, we show that polyamine levels modulate the coating of MTs with MAP4 (MT-associated protein 4), an MT-stabilizing protein, and the spatial distribution of EB1 (end-binding protein 1), an MT plus-end-binding protein. In addition, polyamines favour the formation of gap junctions in NRK cells, a process which requires MT extensions at the cell periphery. The present study provides a basis for a better understanding of the role played by polyamines in MT assembly and establishes polyamine metabolism as a potential cellular target for modulating MT functions.

Anti-proliferative effects of Lethariella zahlbruckneri extracts in human HT-29 human colon cancer cells

This study was performed to elucidate the anti-proliferative effects and the apoptotic mechanisms of extracts from Lethariella zahlbruckneri in HT-29 human colon cancer cells. Both the acetone extract (AEL) and methanolic extract (MEL) of L. zahlbruckneri decreased viable cell numbers in a dose- and time-dependent manner in HT-29 cells. The AEL showed stronger cytotoxicity than MEL. Cell death induced by AEL increased cell populations in the sub-G1 phase, as well as the formation of apoptotic bodies and nuclear condensation, whereas MEL did not. Therefore, the potential of AEL to induce apoptosis was examined. Apoptosis induced by AEL was associated with the activation of initiator caspases-8 and -9, as well as the effector caspase-3. AEL stimulated Bid cleavage. This indicated that the apoptotic action of caspase-8-mediated Bid cleavage leads to the activation of caspase-9. AEL increased the expression of the pro-apoptotic protein, Bax, and decreased the expression of the anti-apoptotic protein, Bcl-2. AEL also increased the expression of the caspase-independent mitochondrial apoptosis factor, AIF, in HT-29 cells. These results indicate that AEL inhibited HT-29 cell proliferation by inducing apoptosis, which might be mediated via both caspase-dependent and -independent pathways.

Induction of apoptosis in HT-29 colon cancer cells by crude saponin from Platycodi Radix

This study examined the apoptotic effects of crude saponins acquired from the roots of Platycodon grandiflorum (SPR) in HT-29 human colon cancer cells. SPR decreased HT-29 cell proliferation in dose- and time-dependent manners by inducing apoptosis via DNA fragmentation and poly (ADP-ribose) polymerase (PARP) cleavage. The apoptosis induced by SPR was associated with the activation of initiator caspases-8 and -9, as well as the effector caspase-3. SPR stimulated Bid cleavage, indicating that the apoptotic action of caspase-8-mediated Bid cleavage leads to the activation of caspase-9. SPR increased the expression of the pro-apoptotic protein, Bax, and decreased the expression of the anti-apoptotic protein, Bcl-2. SPR also increased the expression of the caspase-independent mitochondrial apoptosis factor, AIF, in HT-29 cells. These results indicate that SPR inhibits HT-29 cell proliferation by inducing apoptosis, which may be mediated via both caspase-dependent and -independent pathways.