linoleic-acid and Colonic-Neoplasms

Experiments in animal models of mammary carcinogenesis suggest that fatty acids promote mammary tumors development. This effect depends first on the amount then on the type of fatty acids available. n-6 fatty acids such as linoleic acid generally stimulates mammary tumor growth, while n-3 fatty acids oppose this effect. Conjugated diene fatty acids (CLA) inhibit mammary carcinogenesis when brought at elevated amount. There are limitations in using an animal model in the analysis between nutrition and colorectal cancers. This is ascribable to the following: firstly, the digestive tract of rodents if different from that of humans and secondly, the induction of colon cancer in these animals (chemical carcinogenesis, injection of cancerous cells or transgenesis) does not mimic human colon carcinogenesis. However, on the basis of numerous published data, some important correlations have arisen that could generate hypotheses and guide new epidemiological/interventional and experimental studies. In these animal models it appears that an adequate supply of n-3 PUFAs and oleic acid in food may exert a protective effect at all stages of colon carcinogenesis. On the other hand, an excessive consumption of n-6 PUFAs and of saturated fatty acids could promote colon cancers.

Topics: alpha-Linolenic Acid; Animals; Colonic Neoplasms; Dietary Fats; Dietary Fats, Unsaturated; Fatty Acids; Fatty Acids, Omega-3; Fatty Acids, Omega-6; Fatty Acids, Unsaturated; Female; Fish Oils; Humans; Linoleic Acid; Male; Mammary Neoplasms, Experimental; Models, Animal; Neoplasm Transplantation; Neoplasms, Experimental; Oleic Acid; Prostatic Neoplasms; Rodentia

Conjugated linoleic acid (CLA) is a collective term for positional and geometric isomers of octadecadienoic acid in which the double bonds are conjugated, i.e. contiguous. CLA was identified as a component of milk and dairy products over 20 years ago. It is formed as an intermediate in the course of the conversion of linoleic acid to oleic acid in the rumen. The predominant naturally occurring isomer is the cis-9, trans-11 modification. Treatment of linoleic acid-rich oils such as safflower oil, soybean oil, or maize oil with base and heat will result in the formation of CLA. Two isomers predominate in the synthetic preparation, c9,t11 and t10,c12. CLA has been shown to inhibit chemically-induced skin, stomach, mammary or colon tumours in mice and rats. The inhibition of mammary tumours in rats is effective regardless of type of carcinogen or type or amount of dietary fat. CLA has also been shown to inhibit cholesterol-induced atherosclerosis in rabbits. When young animals (mice, pigs) are placed on CLA-containing diets after weaning they accumulate more body protein and less fat. Since CLA is derived from the milk of ruminant animals and is found primarily in their meat and in products derived from their milk there is a concerted world-wide effort to increase CLA content of milk by dietary means. Its effect on growth (less fat, more protein) is also a subject of active research. The mechanisms underlying the effects of CLA are still moot.

Topics: Animals; Antimutagenic Agents; Antineoplastic Agents; Arteriosclerosis; Body Composition; Colonic Neoplasms; Dairy Products; Female; Linoleic Acid; Mammary Neoplasms, Experimental; Mice; Milk; Rabbits; Rats; Skin Neoplasms

Colorectal cancer is a significant cause of mortality in Western societies. The progression of the disease from normal colonic epithelium to the acquisition of the malignant phenotype is accompanied by numerous genetic and epigenetic alterations. Compelling experimental and epidemiological evidence indicates that diet and nutrition are key factors in the modulation of colorectal cancer. A salient case in point is the recent observation that a dietary regimen based on a Western-style diet provokes in the rodent colon the appearance of preneoplastic lesions in the absence of any genotoxic insult. This review mainly describes dietary factors that inhibit the development and progression of colorectal cancer. Much is unknown about the precise mechanisms of action of chemically disparate nutrients and how they interfere with the development and progression of this disease. Current knowledge about this important issue is summarized. We believe that continuing scrutiny and precise assessment of the benefits (and potential risks) of nutrients in the treatment and prevention of colorectal cancer will prove significant to controlling this devastating disease.

Topics: Animals; Colonic Neoplasms; Diet; Dietary Fiber; Energy Intake; Humans; Linoleic Acid; Nutritional Physiological Phenomena; Rectal Neoplasms; Sphingomyelins

During a study of the mechanism of cancer cachexia, a debilitating condition in which catabolism of host muscle and adipose tissue occurs, it has been observed that the process can be effectively reversed in vivo by the polyunsaturated fatty acid, eicosapentaenoic acid (EPA), but not by other PUFA of either the n-3 or n-6 series. In vitro studies showed that EPA blocked the action of a tumour-produced catabolic factor at the level of the adipocyte, and that the effect of EPA also extended to beta-adrenergic stimuli and polypeptide hormones. Again the effect was specific to EPA and appeared to arise from an inhibition of the elevation of cyclic AMP levels in adipocytes in response to varied stimuli. Using isoprenaline stimulated lipolysis as a model system we have shown that EPA has a direct inhibitory effect on isoprenaline-stimulated adenylate cyclase in isolated plasma membrane fractions with half maximal inhibition at a concentration of 165 microM. The inhibitory effect was specific for EPA and was not shown by docosahexaenoic or arachidonic acids. The inhibitory effect of EPA on adenylate cyclase showed properties similar to hormonal inhibition of the enzyme in that it was (i) GTP-dependent, (ii) non-competitive with isoprenaline, (iii) eliminated following treatment of either adipocytes or plasma membrane fractions with pertussis toxin, which is known to ADP-ribosylate the alpha-subunit of an inhibitory guanine nucleotide-regulatory protein (Gi), thus leading to its inactivation. This suggests that inhibition of cyclic AMP formation by EPA was due, at least in part, to a Gi-mediated inhibition of adenylate cyclase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adenocarcinoma; Adenylyl Cyclases; Adipose Tissue; Animals; Cachexia; Colonic Neoplasms; Cyclic AMP; Dietary Fats; Eicosapentaenoic Acid; Enzyme Activation; Fatty Acids, Omega-3; Fatty Acids, Unsaturated; Gene Expression Regulation; Genes, ras; GTP-Binding Proteins; Humans; Isoproterenol; Linoleic Acid; Linoleic Acids; Lipid Metabolism; Lipolysis; Mice; Neoplasms; Signal Transduction

Human and animal studies support that consuming a high level of linoleic acid (LA, 18:2ω-6), an essential fatty acid and key component of the human diet, increases the risk of colon cancer. However, results from human studies have been inconsistent, making it challenging to establish dietary recommendations for optimal LA intake. Given the importance of LA in the human diet, it is crucial to better understand the molecular mechanisms underlying its potential colon cancer-promoting effects. Using LC-MS/MS-based targeted lipidomics, we find that the cytochrome P450 (CYP) monooxygenase pathway is a major pathway for LA metabolism in vivo. Furthermore, CYP monooxygenase is required for the colon cancer-promoting effects of LA, since the LA-rich diet fails to exacerbate colon cancer in CYP monooxygenase-deficient mice. Finally, CYP monooxygenase mediates the pro-cancer effects of LA by converting LA to epoxy octadecenoic acids (EpOMEs), which have potent effects on promoting colon tumorigenesis via gut microbiota-dependent mechanisms. Overall, these results support that CYP monooxygenase-mediated conversion of LA to EpOMEs plays a crucial role in the health effects of LA, establishing a unique mechanistic link between dietary fatty acid intake and cancer risk. These results could help in developing more effective dietary guidelines for optimal LA intake and identifying subpopulations that may be especially vulnerable to LA's negative effects.

Topics: Animals; Chromatography, Liquid; Colonic Neoplasms; Cytochrome P-450 Enzyme System; Diet; Eicosanoids; Humans; Linoleic Acid; Mice; Tandem Mass Spectrometry

There is growing interest in the crosstalk between the gut microbiome, host metabolomic features, and disease pathogenesis. The current investigation compared long-term (26 week) and acute (3 day) dietary spinach intake in a genetic model of colorectal cancer. Metabolomic analyses in the polyposis in rat colon (Pirc) model and in wild-type animals corroborated key contributions to anticancer outcomes by spinach-derived linoleate bioactives and a butanoate metabolite linked to increased α-diversity of the gut microbiome. Combining linoleate and butanoate metabolites in human colon cancer cells revealed enhanced apoptosis and reduced cell viability, paralleling the apoptosis induction in colon tumors from rats given long-term spinach treatment. Mechanistic studies in cell-based assays and in vivo implicated the linoleate and butanoate metabolites in targeting histone deacetylase (HDAC) activity and the interferon-γ (IFN-γ) signaling axis. Clinical translation of these findings to at-risk patients might provide valuable quality-of-life benefits by delaying surgical interventions and drug therapies with adverse side effects.

Topics: Animals; Butyric Acid; Colonic Neoplasms; Diet; Humans; Interferon-gamma; Linoleic Acid; Metabolomics; Rats; Spinacia oleracea

The aim of this study is to explore essential oil from the bark of Cedrus deodara (CDEO) as an potential anticancer agent.. The frontline drugs against cancer in clinical settings are posing challenges of resistance and other detrimental side-effects. This has led to the exploration of new anticancer chemical entities from natural sources, particularly plant-based products such as essential oils that serve as vast repositories of pharmacologically active substances for combating cancer.. The objective is to isolate and characterize the essential oil from the bark of Cedrus deodara (CDEO) and evaluate its potential as an anticancer agent and delineate the possible underlying mechanism of action.. Cedrus deodara essential oil from bark (CDEO) was obtained by hydro-distillation and analyzed by GC/MS for vital constituents. Further, in vitro cytotoxic potential was measured by MTT assay against a panel of cancer cell lines. The apoptosis-inducing potential of CDEO was analyzed by mitochondrial membrane potential loss (ΔΨm) and nuclear fragmentation assay. Besides, wound healing assay and colonogenic assay were employed to check the anti-metastatic potential of CDEO. Molecular docking approaches were employed for target identification, while immuno-blotting was carried out for target validation.. The major components identified were 2-(tert-Buyl)-6-methyl-3-(2- (trifluoromethyl) benzyl)imidazo [1,2-a]pyridine (26.32 %);9- Octadecenoic acid (8.015 %); Copaene (5.181 %);2-(4-Methoxy-2,6-dimethylphenyl) -3-methyl-2H- benzo[g]indazole(4.36 %) and 9(E),11(E)- Conjugated linoleic acid (4.299 %). Further, potent in vitro cytotoxic activity with IC50 values of 11.88 μg/ ml and 14.63 μg/ ml in colon cancer cell lines of HCT-116 and SW-620, respectively. Further, a significant and dose-dependent decrease in colony formation, cell migration, induction of ROS formation and loss in ΔΨm was observed. Additionally, major compounds identified were chosen for ligandprotein binding interaction studies to predict the molecular targets in colon cancer. It was observed that compounds such as 9-Octadecenoic acid;4H-1- Benzopyran-4-one, 3-(3,4-dimethoxyphenyl)-6,7- dimethoxy; 2-(4-Methoxy-2,6-dimethylphenyl) -3-methyl-2H-benzo [g]indazole and 2-Bornanol,5-(2,4- dinitro phenyl) hydrazono have a prominent binding affinity with NF-κB. This was also further validated by immuno-blotting results wherein CDEO treatment in colon cancer cells led to the abrogation of NFκB, and the Bcl-2-associated X protein (Bax): B-cell lymphoma (Bcl)-2 ratio was up-regulated leading to enhanced cleaved caspase 3 formation and subsequent apoptosis.. These results unveil CDEO inhibits cell proliferation and induces apoptosis in colon cancer cells, which can be attributed to the abrogation of the NFκB signaling pathway.

Topics: Antineoplastic Agents; Apoptosis; Caspase 3; Cedrus; Cell Line, Tumor; Cell Proliferation; Colonic Neoplasms; Drug Screening Assays, Antitumor; Humans; Linoleic Acid; Molecular Docking Simulation; NF-kappa B; Oils, Volatile; Plant Bark; Plant Extracts; Plant Oils; Protein Binding; Reactive Oxygen Species; Stearic Acids; Structure-Activity Relationship

Topics: Animals; beta Catenin; Colonic Neoplasms; Humans; Linoleic Acid; Low Density Lipoprotein Receptor-Related Protein-5; Mice; Signal Transduction; Transfection; Wnt Signaling Pathway

Topics: Antihypertensive Agents; Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Cell Survival; Colonic Neoplasms; Drug Therapy, Combination; Humans; Linoleic Acid; PPAR gamma; Telmisartan

Biodegradable polymeric nanoparticles (NPs) have been used frequently as nanocarriers for anticancer drugs. Linoleic acid conjugated SN38 (LA-SN38)-loaded NPs (EBNPs) were developed using biodegradable poly (ethylene oxide)-poly (butylene oxide) (PEO-PBO) diblock copolymer by titration hydration method without using a toxic organic solvent. The EBNPs had high drug loading efficiency and entrapment efficiency for LA-SN38, at 7.53% and 93.55%, respectively. The polydispersity index (PDI) and average diameter were 0.173 ± 0.019 and 226.1 ± 1.2 nm, respectively. The transmission electron microscope (TEM) image presented that the NPs were homogeneous in size and had spherical structures. In vitro study showed the release behavior of EBNPs was slow and sustained. Furthermore, cytotoxicity and apoptosis assay proved that EBNPs were more effective in growth inhibition of human colon cancer cells. Cell uptake experiments further demonstrated that EBNPs could avoid the phagocytosis by macrophages and promote the uptake by cancer cells. In vivo, EBNPs had prolonged blood circulation time and tumor selectivity in biodistribution. The tumor inhibitory rate of EBNPs was higher compared to SNPs group and CPT-11group (P < 0.01), and the drug did not show significant systemic toxicity at the tested dose. These results indicated that EBNPs are a promising candidate for delivery of LA-SN38 to treat colorectal cancer.

Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Proliferation; Cell Survival; Colonic Neoplasms; Drug Screening Assays, Antitumor; HCT116 Cells; HT29 Cells; Humans; Irinotecan; Linoleic Acid; Male; Mice; Nanoparticles; Neoplasms, Experimental; Optical Imaging; Particle Size; Polymers; Rats; Rats, Sprague-Dawley; Surface Properties; Tissue Distribution; Tumor Cells, Cultured

Evidence shows that vitamin D and cyclooxygenase type 2 (COX-2) might play role in aetiology/progression of cancer. It is suggested that antitumour effect of vitamin D depends on vitamin D-receptor (VDR) expression. Aim of the study was to determine vitamin D and polyunsaturated fatty acids in colorectal cancer patients.. A total of 39 patients with colorectal cancer (mean ± SD age: 65.5 ± 6.8 years) and 25 controls (mean ± SD age: 51.0 ± 6.9 years) were studied. 25-hydroxycholecalciferol-25(OH)D. The mean value of 25(OH)D. The assessment of vitamin D status in patients with colorectal cancer should include measurement of mRNA VDR expression in tumour tissue.

Topics: Aged; Arachidonic Acid; Calcifediol; Case-Control Studies; Colon; Colonic Neoplasms; Cyclooxygenase 2; Disease Progression; Female; Humans; Intestinal Mucosa; Linoleic Acid; Male; Middle Aged; Neoplasm Staging; Receptors, Calcitriol; Rectal Neoplasms

The potential effects of 2 types of fatty acids on colorectal cancer (CRC) were assessed using cancer stromal cells. Linoleic acid (LA; C-18, n-6 unsaturated fatty acid) and elaidic acid (EA; C-18, trans acid), both known to affect colon carcinogenesis and cancer progression, were administered by gavage to BALB/c mice, which were inoculated with CT26 syngeneic colon cancer cells in the back. Both EA and LA treatments enhanced tumor growth and metastasis. EA and LA also increased the number of CD133-positive stromal cells in the tumor capsule. Importantly, those cancer cells at the tumor periphery, physically attached to CD133-positive stromal cells, also expressed CD133. These findings suggest that EA and LA might induce stemness in cancer cells through physical association and promote cancer metastasis.

Topics: AC133 Antigen; Animals; Carcinogenesis; Carrier Proteins; Cell Line, Tumor; Cell Movement; Colonic Neoplasms; Disease Models, Animal; Fatty Acids; GTP-Binding Proteins; Isografts; Linoleic Acid; Male; Mice; Mice, Inbred BALB C; Neoplasm Metastasis; Nuclear Proteins; Oleic Acid; Oleic Acids; RNA-Binding Proteins; Stromal Cells

DNA methylation and histone acetylation contribute to the transcriptional regulation of genes involved in apoptosis. We have demonstrated that docosahexaenoic acid (DHA, 22:6 n-3) and butyrate enhance colonocyte apoptosis. To determine if DHA and/or butyrate elevate apoptosis through epigenetic mechanisms thereby restoring the transcription of apoptosis-related genes, we examined global methylation; gene-specific promoter methylation of 24 apoptosis-related genes; transcription levels of Cideb, Dapk1, and Tnfrsf25; and global histone acetylation in the HCT-116 colon cancer cell line. Cells were treated with combinations of (50 µM) DHA or linoleic acid (18:2 n-6), (5 mM) butyrate or an inhibitor of DNA methyltransferases, and 5-aza-2'-deoxycytidine (5-Aza-dC, 2 µM). Among highly methylated genes, the combination of DHA and butyrate significantly reduced methylation of the proapoptotic Bcl2l11, Cideb, Dapk1, Ltbr, and Tnfrsf25 genes compared to untreated control cells. DHA treatment reduced the methylation of Cideb, Dapk1, and Tnfrsf25. These data suggest that the induction of apoptosis by DHA and butyrate is mediated, in part, through changes in the methylation state of apoptosis-related genes.

Topics: Acetylation; Antimetabolites, Antineoplastic; Apoptosis; Apoptosis Regulatory Proteins; Azacitidine; Bcl-2-Like Protein 11; Butyrates; Cell Line, Tumor; Colonic Neoplasms; Death-Associated Protein Kinases; Decitabine; DNA Methylation; DNA Modification Methylases; Docosahexaenoic Acids; HCT116 Cells; Histones; Humans; Linoleic Acid; Lymphotoxin beta Receptor; Membrane Proteins; Promoter Regions, Genetic; Proto-Oncogene Proteins; Receptors, Tumor Necrosis Factor, Member 25; Transcription, Genetic

High-mobility group box 1 (HMGB1) was closely associated with progression and metastasis of colorectal cancer.. We examined the significance of HMGB1 in causing colon carcinogenesis induced by azoxymethane (AOM) injection in Fischer 344 rats fed on a control diet (group C), a 15% linoleic acid (LA) diet (group L), a control diet with 10% glucose drink (group G), and a 15% LA diet with a 10% glucose drink (group L+G).. Group L+G showed the highest body weight and calorie intake. Serum and mucosal HMGB1 levels were temporally increased in all groups, while the highest levels were observed in group L+G. Mucosal HMGB1 levels were correlated with cancer multiplicity and nodal metastases. In the AOM-injected rats fed the 15% LA diet with 10% glucose drink, administration of HMGB1 antibody suppressed serum HMGB1 concentration and cancer multiplicity.. These data suggest that dietary LA and glucose provided the synergistic effect on AOM-induced rat colon cancer through HMGB1 induction.

Topics: Animals; Azoxymethane; Carcinogens; Colonic Neoplasms; Diet; Drug Synergism; Glucose; HMGB1 Protein; Linoleic Acid; Male; Random Allocation; Rats; Rats, Inbred F344

We examined the effect of linoleic acid (LA) on tumor formation. Cell growth was suppressed by LA in a dose-dependent manner in MKN28 and Colo320 cells. Continuous treatment with LA provided growth arrest in both cells at 5-7 weeks after the treatment. LA-pretreated MKN28 and Colo320 cells showed higher tumorigenicity (9/10 and 10/10, respectively) than nontreated cells (2/10 and 3/10, respectively; p < 0.01) in nude mice. In contrast, LA-pretreated MKN28 and Colo320 cells showed more suppressed tumor growth than nontreated cells (p < 0.01). LA-pretreated MKN28 and Colo320 cells with LA administration after the inoculation did not form macroscopic tumors. Histological examination revealed small cancer cell aggregations, which showed no proliferative activity. In LA-treated MKN28 and Colo320 cells, protein production of Bcl-2 was increased, whereas Bak, EGFR and VEGF levels were decreased. These findings suggest that LA might induce quiescence and subsequent dormancy in cancer cells.

Topics: Animals; bcl-2 Homologous Antagonist-Killer Protein; Cell Line, Tumor; Cell Proliferation; Colonic Neoplasms; Dose-Response Relationship, Drug; ErbB Receptors; Humans; Linoleic Acid; Mice; Mice, Inbred BALB C; Mice, Nude; Proto-Oncogene Proteins c-bcl-2; Stomach Neoplasms; Vascular Endothelial Growth Factor A; Xenograft Model Antitumor Assays

Intake of linoleic acid (LA) increased etheno-DNA adducts induced by lipid peroxidation (LPO) in white blood cells (WBC) of female but not of male volunteers [J. Nair, C.E. Vaca, I. Velic, M. Mutanen, L.M. Valsta, H. Bartsch, High dietary omega-6 polyunsaturated fatty acids drastically increase the formation of etheno-DNA adducts in white blood cells of female subjects, Cancer Epidemiol. Biomarkers Prev. 6 (1997) 597-601]. Etheno-adducts were measured in rats gavaged with LA, oleic acid (OA) and saturated fatty acid rich coconut oil for 30 days. DNA from organs and total WBC was analyzed for 1, N(6)-ethenodeoxyadenosine (varepsilondA) and 3, N(4)-ethenodeoxycytidine (varepsilondC) by immunoaffinity/(32)P-postlabeling. Colon was the most affected target with LA-treatment, where etheno-adducts were significantly elevated in both sexes. In WBC both adducts were elevated only in LA-treated females. Unexpectedly, OA treatment enhanced etheno-adduct levels in prostate 3-9 fold. Our results in rodents confirm the gender-specific increase of etheno-adducts in WBC-DNA, likely due to LPO induced by redox-cycling of 4-hydroxyestradiol. Colon was a target for LPO-derived DNA-adducts in both LA-treated male and female rats, supporting their role in omega-6 PUFA induced colon carcinogenesis.

Topics: Animals; Cattle; Coconut Oil; Colon; Colonic Neoplasms; Deoxyadenosines; Deoxycytidine; DNA Adducts; Female; Humans; In Vitro Techniques; Leukocytes; Linoleic Acid; Lipid Peroxidation; Male; Oleic Acid; Organ Specificity; Plant Oils; Rats; Sex Characteristics

Two different pathways of linoleic acid (LA) metabolism have opposite effects on the development of colonic cancer: a protumoral prostaglandin cascade metabolized by cyclooxygenase (COX)-2, and an antitumoral peroxisome proliferator-activated receptor (PPAR)-gamma ligands metabolized by 15-lipooxygenase (LOX)-1. The aim was to examine the switching of the two LA metabolic pathways in colonic adenomas and carcinomas.. The expression of 15LOX-1 mRNA and COX-2 protein was examined in 54 adenomas, 21 pTis carcinoma-in-adenoma lesions and 36 pT3/p Stage II carcinomas of the colon by in-situ hybridization and immunohistochemistry, respectively.. 15LOX-1 expression was found in 89% (48 of 54) of adenomas, 43% (nine of 21) of adenomas and 10% (two of 21) of carcinomas in carcinoma-in-adenoma lesions, but not in pT3 carcinomas (P < 0.0001). In contrast, COX-2 production was found in 11% (six of 54) of adenomas, 52% (11 of 21) of adenomas and 71% (15 of 21) of carcinomas in carcinoma-in-adenoma lesions, and 92% (33 of 36) of pT3 carcinomas (P < 0.0001). Concurrence of 15LOX-1 down-regulation and COX-2 up-regulation was found in 6% (three of 54) of adenomas, 33% (seven of 21) of adenomas and 71% (15 of 21) of carcinomas in carcinoma-in-adenoma lesions, and 92% (33 of 36) of pT3 carcinomas (P < 0.0001).. These results suggest that switching of LA metabolism by reversal of the expression of 15LOX-1 and COX-2 is associated with acquisition of malignant potential in colonic neoplasia.

Topics: Adenoma; Aged; Aged, 80 and over; Arachidonate 15-Lipoxygenase; Carcinoma; Colonic Neoplasms; Cyclooxygenase 2; Disease Progression; Female; Gene Expression Regulation, Neoplastic; Humans; Linoleic Acid; Male; Middle Aged; Neoplasm Staging; RNA, Messenger

The effect on peritoneal metastasis of linoleic acid (LA) was examined using in vitro treatment of cancer cells and mouse peritoneal metastasis models. Firstly, cell growth of MKN28 human gastric cancer cells and Colo320 human colon cancer cells was suppressed by LA in a dose-dependent manner with increment of apoptosis. LA-induced growth inhibition was recovered by the exposure to antisense S-oligodeoxynucleotide for peroxisome proliferator-activated receptor gamma (PPARgamma) or 15-lipoxygenase-1, which converts LA to PPARgamma ligands. LA significantly inhibited invasion into type-IV collagen-coated membrane of MKN28 and Colo320 cells (p<0.05). BALB/c nu/nu mice inoculated with MKN28 and Colo320 cells into their peritoneal cavities were administrated with LA intraperitoneally (weekly, four times). The LA treatment significantly diminished the number of metastatic foci of both cells in the peritoneal cavity (p<0.05). Protein production in MKN28 and Colo320 cells treated with LA showed a decrease of epidermal growth factor receptor and an increase of Bax. These findings suggest that LA inhibits invasion and metastasis of human gastric and colon cancer cells by nondietary administration.

Topics: Animals; Antineoplastic Agents; Apoptosis; Arachidonate 15-Lipoxygenase; bcl-2-Associated X Protein; Cell Line, Tumor; Cell Movement; Colonic Neoplasms; Cricetinae; Dose-Response Relationship, Drug; ErbB Receptors; Humans; Linoleic Acid; Lipoxygenase Inhibitors; Mice; Mice, Inbred BALB C; Mice, Nude; Oligodeoxyribonucleotides, Antisense; Peritoneal Neoplasms; PPAR gamma; Stomach Neoplasms; Xenograft Model Antitumor Assays

Dietary heterocyclic aromatic amines (HCA) and polyunsaturated fatty acids (PUFA) are both believed to play a role in colon carcinogenesis, and are both substrate for the enzyme cyclooxygenase (COX). In HCA-7 cells, highly expressing isoform COX-2, we investigated the effects of PUFA on prostaglandin synthesis and DNA adduct formation by the HCA 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 2-amino-3-methylimidazo[4,5-f]quinoline (IQ). Furthermore, we studied the role of COX, COX-2 in particular, and cytochrome P4501A2 (CYP1A2) by using the enzyme inhibitors indomethacin (IM), NS-398, and phenethyl isothiocyanate (PEITC), respectively. COX-mediated formation of prostaglandin E2 (PGE2) from linoleic acid (LA) showed that HCA-7 cells can convert LA into arachidonic acid (AA). Alternatively, eicosapentaenoic acid (EPA) was found to compete with AA for COX. Strongly decreased PGE2 levels by addition of IM demonstrated involvement of COX in PUFA metabolism. Both IM and NS-398 inhibited adduct formation by HCA to nearly the same extent, indicating involvement of COX-2 rather than COX-1, while CYP1A2 activity in HCA-7 cells was demonstrated by addition of PEITC. Overall, inhibiting effects were stronger for PhIP than for IQ. HCA-DNA adduct formation was stimulated by addition of PUFA, although high PUFA concentrations partly reduced this stimulating effect. Finally, similar effects for n-3 and n-6 fatty acids suggested that adduct formation may not be the crucial mechanism behind the differential effects of PUFA on colon carcinogenesis that have been described. These results show that COX, and COX-2 in particular, can play a substantial role in HCA activation, especially in extrahepatic tissues like the colon. Furthermore, the obvious interactions between PUFA and HCA in COX-2 expressing cancer cells may be important in modulating colorectal cancer risk.

Topics: Adenocarcinoma; Amines; Cell Survival; Colonic Neoplasms; Cytochrome P-450 CYP1A2; Cytochrome P-450 CYP1A2 Inhibitors; Dinoprostone; DNA Adducts; Enzyme Inhibitors; Fatty Acids, Unsaturated; Heterocyclic Compounds; Humans; Linoleic Acid; Prostaglandin-Endoperoxide Synthases; Tumor Cells, Cultured

The relationship between 15(S)-HETE and 13(S)-HODE from different human tumor cells exposed to n-6 and n-3 essential fatty acids (EFAs) and E-cadherin expression was studied. Colon cancer cells (HRT-18) exposed to gamma linoleic acid (18:3n-6, GLA) and eicosapentaenoic (20:5n-3, EPA) (50microM) showed an increased expression of E-cadherin. Breast cancer (MCF-7) exposed to EPA showed an increment whereas GLA had no effect on E-cadherin expression. No expression of E-cadherin was observed for urothelial cancer (T-24) after GLA or EPA treatment. Significant levels of 15(S)-HETE and 13(S)-HODE were detected after GLA or EPA treatment for all tumor lines. E-cadherin expression was inversely proportional to the 13(S)-HODE:15(S)-HETE ratio when cells were pretreated with GLA or EPA. Nevertheless, the liberation of these metabolites seems to be independent of the E-cadherin expression. The increase in the13(S)-HODE:15(S)-HETE correlates to a decrease in the expression of E-cadherin. Both factors may play a role in metastasis development.

Topics: Arachidonic Acid; Breast Neoplasms; Cadherins; Cell Differentiation; Colonic Neoplasms; Female; Humans; Hydroxyeicosatetraenoic Acids; Immunohistochemistry; Linoleic Acid; Linoleic Acids; Neoplasm Metastasis; Tumor Cells, Cultured; Urinary Bladder Neoplasms; Urothelium

Conjugated linoleic acid (CLA) has chemoprotective properties in experimental cancer models, and in vitro studies have shown that CLA inhibits HT-29 colon cancer cell growth. ErbB2 and ErbB3 have been implicated in the development of colon cancer, and both proteins are expressed at high levels in the HT-29 cell line. Activation of ErbB2/ErbB3 heterodimers is regulated by the ErbB3 ligand heregulin. To examine CLA regulation of HT-29 cell proliferation and apoptosis and the influence of CLA on the ErbB3 signaling pathway, HT-29 cells were cultured in the presence of CLA and/or heregulin. CLA inhibited DNA synthesis and induced apoptosis of HT-29 cells. Although the addition of heregulin-alpha led to an increase in cell number, it was not able to counteract the negative growth regulatory effect of CLA. Immunoprecipitation/Western blot studies revealed that CLA inhibited heregulin-alpha-stimulated phosphorylation of ErbB2 and ErbB3, recruitment of the p85 subunit of phosphoinositide 3-kinase (PI3-kinase) to the ErbB3 receptor, ErbB3-associated PI3-kinase activities, and phosphorylation of Akt. CLA decreased ErbB2 and ErbB3 mRNA and protein levels in a dose-dependent manner. In conclusion, we demonstrate that CLA inhibits cell proliferation and stimulates apoptosis in HT-29 cells and that this may be mediated by its ability to downregulate ErbB3 signaling and the PI3-kinase/Akt pathway.

Topics: Adenocarcinoma; Apoptosis; Cell Division; Colonic Neoplasms; Dose-Response Relationship, Drug; Gene Expression Regulation; Humans; Linoleic Acid; Neuregulin-1; Receptor, ErbB-3; Signal Transduction; Tumor Cells, Cultured

Conjugated linoleic acid (CLA) has chemoprotective properties in a variety of experimental cancer models. We have previously observed that dietary CLA inhibits colon tumorigenesis induced by 1,2-dimethylhydrazine in rats. In addition, our in vitro studies have shown that CLA inhibits DNA synthesis and induces apoptosis in HT-29 cells, the human colon adenocarcinoma cell line. The insulin-like growth factor (IGF) system regulates the growth of HT-29 cells by an autocrine mechanism. The present study examined whether the growth inhibitory effect of CLA is related to changes in the IGF system in HT-29 cells. To determine whether CLA inhibits IGF-II production, HT-29 cells were incubated in serum-free medium in the presence of various concentrations of CLA. CLA decreased protein levels of both mature and pro IGF-II and IGF-II transcripts. Whereas exogenous IGF-I and IGF-II produced an increase in cell number, neither IGF-I nor IGF-II counteracted the negative growth regulatory effect of CLA. Reverse transcriptase-polymerase chain reaction and Western blot analysis of total cell lysates revealed that CLA decreased IGF-I receptor (IGF-IR) transcript and protein levels in a dose-dependent manner. Immunoprecipitation/Western blot studies revealed that CLA inhibited IGF-I-induced phosphorylation of IGF-IR and insulin-receptor substrate (IRS)-1, recruitment of the p85 regulatory subunit of phosphatidylinositol 3-kinase (PI3K) to IGF-IR, IGF-IR-associated PI3K activity, and phosphorylated Akt and extracellular signal-regulated kinase (ERK)-1/2 levels. In conclusion, the inhibition of cell proliferation and induction of apoptosis by CLA in HT-29 cells may be mediated in part by its ability to decrease IGF-II synthesis and to downregulate IGF-IR signaling and the PI3K/Akt and ERK-1/2 pathways.

Topics: Colonic Neoplasms; Down-Regulation; Enzyme Activation; Humans; Insulin-Like Growth Factor II; Linoleic Acid; Mitogen-Activated Protein Kinases; Phosphatidylinositol 3-Kinases; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; Receptor, IGF Type 1; RNA, Messenger; Tumor Cells, Cultured

We investigated the effects of conjugated linoleic acid (CLA) on tumor incidence, apoptosis, eicosanoid formation, 1,2-diacylglycerol (DAG), and fatty acid profiles of colonic mucosa in 1,2-dimethylhydrazine-treated rats fed different types of dietary fats.. One hundred twenty male 7-wk-old Sprague-Dawley rats were assigned to a beef tallow (BT) diet or a fish oil (FO) diet; each group was further divided into two groups, one with CLA supplementation (BTC and FOC) and the other without (BT and FO). All groups were fed for 30 wk on experimental diets that contained 12% (w/w) dietary fat (including 1% CLA for the BTC and FOC groups) and were intramuscularly injected with 1,2-dimethylhydrazine for 6 wk, for a total dose of 180 mg/kg of body weight.. Rats fed the FOC, BTC, or FO (omega-3 fatty acids, mainly docosahexaenoic acid) showed a reduced incidence of tumors, increased apoptotic index values (P < 0.05), and lower levels of eicosanoids (prostaglandin E(2) and thromboxane B(2)) and DAG in colonic mucosa (P < 0.05). CLA and docosahexaenoic acid were incorporated into membrane phospholipids and significantly reduced the distribution of arachidonic acid in colonic mucosal phospholipids. Because CLA and omega-3 fatty acids reduced tumor incidence and levels of cell response regulators (prostaglandin E(2), thromboxane B(2), and DAG), they may share at least one common path of action in promoting the apoptotic process of colon carcinogenesis.. These results suggested that increased apoptosis by dietary CLA may be attributed, at least in part, to changes in arachidonic acid metabolism in rats. Therefore, CLA may have anticarcinogenic effects by inducing apoptosis through modification of signal transduction in colonic mucosal cells.

Topics: 1,2-Dimethylhydrazine; Animals; Apoptosis; Biomarkers; Carcinogens; Colonic Neoplasms; Dietary Supplements; Dose-Response Relationship, Drug; Fatty Acids, Omega-3; Incidence; Linoleic Acid; Male; Random Allocation; Rats; Rats, Sprague-Dawley; Signal Transduction

The nuclear hormone receptor peroxisome proliferator-activated receptor (PPAR) gamma plays an important role in the differentiation of intestinal cells and other tissues. Real-time PCR examination of PPAR mRNA for gamma1, gamma2 and gamma3, in Caco-2 and HCT-116 colon cell lines showed that gamma3 is the most abundant message in both lines. Treatment of Caco-2 cells with sodium butyrate, which induces cell differentiation, also leads to an increase in all three PPAR mRNAs. In contrast, treatment of HCT-116 cells with sodium butyrate, which does not lead to differentiation of these cells, causes a decrease in the amount of all three PPAR mRNAs. Furthermore, the amount of PPAR mRNA is greater in Caco-2 cells than in HCT-116 cells at all times examined. As several oxidative metabolites of linoleic acid, including 13-hydroxyoctadecadienoic acid (13-HODE) and 13-oxooctadecadienoic acid (13-OXO) have been shown to bind PPAR, and there is a strong positive correlation between enzymes for metabolism of linoleate oxidation products, intestinal cell differentiation and the distribution of PPAR, we also performed a detailed investigation of the activation of PPAR gamma by 13-HODE and 13-OXO. For these experiments, Caco-2 and HCT-116 cells were transfected with constructs containing PPAR gamma1 or gamma2 then a PPRE-luc reporter construct. Exposure of transfected cells to micromolar concentrations of 13-HODE or 13-OXO produced concentration-dependent increases in luciferase activity. In addition, the two linoleate metabolites activate endogenous PPAR in these cell lines transfected with only PPRE-luc. The data substantiate the contention that oxidation products of linoleic acid are metabolically produced endogenous ligands for PPAR gamma and that PPAR gamma plays an important role in the differentiation of intestinal cells.

Topics: Base Sequence; Cell Line, Tumor; Colonic Neoplasms; DNA Primers; Humans; Ligands; Linoleic Acid; Oxidation-Reduction; Receptors, Cytoplasmic and Nuclear; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Transcription Factors

A commercially available mixture of conjugated linoleic acid (CLA) isomers decreases colon cancer cell growth. We compared the individual potencies of the two main isomers in this mixture [cis-9,trans-11 (c9t11) and trans-10,cis-12 (t10c12)] and assessed whether decreased cell growth is related to changes in secretion of insulin-like growth factor II (IGF-II) and/or IGF-binding proteins (IGFBPs), which regulate Caco-2 cell proliferation. Cells were incubated in serum-free medium with different concentrations of the individual CLA isomers. t10c12 CLA dose dependently decreased viable cell number (55 +/- 3% reduction 96 h after adding 5 microM t10c12 CLA). t10c12 CLA induced apoptosis and decreased DNA synthesis, whereas c9t11 CLA had no effect. Immunoblot analysis of 24-h serum-free conditioned medium using a monoclonal anti-IGF-II antibody revealed that Caco-2 cells secreted both a mature 7,500 molecular weight (M(r)) IGF-II and higher M(r) forms of IGF-II. The levels of the higher M(r) and the mature form of IGF-II were decreased 50 +/- 3% and 22 +/- 2%, respectively, by 5 microM t10c12 CLA. c9t11 CLA had no effect. Ligand blot analysis of conditioned medium using 125I-labeled IGF-II revealed that t10c12 CLA slightly decreased IGFBP-2 production; c9t11 CLA had no effect. Exogenous IGF-II reversed t10c12 CLA-induced growth inhibition and apoptosis. These results indicate that CLA-inhibited Caco-2 cell growth is caused by t10c12 CLA and may be mediated by decreasing IGF-II secretion in Caco-2 cells.

Topics: Apoptosis; Caco-2 Cells; Cell Division; Colonic Neoplasms; Dose-Response Relationship, Drug; Humans; Insulin-Like Growth Factor II; Linoleic Acid; RNA, Messenger

Fatty acids are generally considered as agonists for peroxisome proliferator-activated receptors (PPARs). Fatty acids have been shown to bind to and transactivate PPARs; it is not known whether fatty acids act as generalized agonists for PPARs in different cell types, and thus, stimulate the expression of PPAR-regulated target genes. Here, we investigated the potency of unsaturated fatty acids on transactivation of PPRE, DNA-binding activity of PPARs, and the expression of a PPAR-regulated gene product, CD36. Docosahexaenoic acid (DHA) suppressed the basal and PPAR agonist-induced transactivation of PPRE, and DNA binding of PPARs in colon tumor cells (HCT116). The suppression of PPAR transactivation by DHA leads to reduced expression of CD36 in HCT116 cells and human monocytic cells (THP-1) as determined by promoter reporter gene assay and flow cytometric analysis. Our results demonstrate that DHA and other unsaturated fatty acids act as antagonists instead of agonists for transactivation of PPRE and PPAR-regulated gene expression in the cell lines tested. These results suggest that PPAR-mediated gene expression and cellular responses can be dynamically modulated by different types of dietary fatty acids consumed.

Topics: Binding Sites; CD36 Antigens; Colonic Neoplasms; Dietary Fats, Unsaturated; DNA; Docosahexaenoic Acids; Fatty Acids, Unsaturated; Gene Expression; Humans; Linoleic Acid; Receptors, Cytoplasmic and Nuclear; Transcription Factors; Transcriptional Activation; Tumor Cells, Cultured

Topics: Adenoma; Animals; Anticarcinogenic Agents; Colonic Neoplasms; Disease Models, Animal; Drinking; Fatty Acids; Genes, APC; Linoleic Acid; Male; Mice; Mice, Mutant Strains; Random Allocation

The modifying effects of dietary feeding of conjugated linolenic acid (CLN) isolated from the seeds of bitter gourd (Momordica charantia) on the development of azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) were investigated in male F344 rats to predict its possible cancer chemopreventive efficacy. The effect of CLN on the proliferating cell nuclear antigen (PCNA) index in colonic ACF was also examined. Rats were given subcutaneous injections of AOM (20 mg/kg body weight) once a week for 2 weeks to induce ACF. They also received the experimental diet containing 0.01%, 0.1% or 1% CLN for 5 weeks, starting one week before the first dosing of AOM. AOM exposure produced a substantial number of ACF (108 +/- 21/rat) at the end of the study (week 4). Dietary administration of CLN caused a significant reduction in the frequency of ACF: 87 +/- 14 (19.4% reduction, P < 0.05) at a dose of 0.01%, 69 +/- 28 (36.1% reduction, P < 0.01) at a dose of 0.1% and 40 +/- 6 (63.0% reduction, P < 0.001) at a dose of 1%. Also, CLN administration lowered the PCNA index and induced apoptosis in ACF. These findings might suggest possible chemopreventive activity of CLN in the early phase of colon tumorigenesis through modulation of cryptal cell proliferation activity and/or apoptosis.

Topics: Animals; Antioxidants; Apoptosis; Azoxymethane; Colonic Neoplasms; Dietary Fats, Unsaturated; Fatty Acids; Linoleic Acid; Male; Precancerous Conditions; Proliferating Cell Nuclear Antigen; Rats; Rats, Inbred F344; Receptors, Cytoplasmic and Nuclear; Transcription Factors

Dietary n-3 polyunsaturated fatty acids (PUFAs), as compared with n-6 PUFAs, suppress cellular production of prostaglandins and tumor cell growth both in vitro and in vivo. However, the mechanism by which n-3 PUFAs suppress tumor growth is not understood. We investigated whether the suppression of tumor cell growth by dietary n-3 PUFAs is mediated through inhibition of cyclooxygenase (COX). A colon tumor cell line, HCT-116, that does not express COX was stably transfected with the constitutively expressed COX-1 or the inducible COX-2 cDNA using a retroviral transfection and infection system. Athymic nude mice transplanted with the cells expressing enzymatically active COX were fed isocaloric diets containing either safflower oil or fish oil for 2 weeks before the start of the experiment and for an additional 21 days after transplantation. Both tumor volume and tumor burden (tumor volume/body weight) were significantly reduced in mice fed the fish oil diet as compared with safflower oil-fed mice. This reduction occurred even in control mice that received injections with cells infected with the retroviral vector without COX-1 or COX-2 cDNA. The growth of tumor cells expressing COX was not different from the growth of those transfected with the vector alone in the nude mice and in soft agar. N-3 PUFAs, as compared with linoleic acid, also inhibited the growth of these cells in culture. This growth inhibition by n-3 PUFAs was not affected by COX-1 or COX-2 overexpression. Contrary to general belief, these results indicate that the suppression of tumor growth by dietary n-3 PUFAs is mediated through COX-independent pathways.

Topics: Animals; Cell Adhesion; Cell Division; Colonic Neoplasms; Cyclooxygenase 1; Cyclooxygenase 2; Diet; DNA, Complementary; Fatty Acids, Omega-3; Fatty Acids, Unsaturated; Female; Growth Inhibitors; Humans; Isoenzymes; Linoleic Acid; Membrane Proteins; Mice; Mice, Nude; Prostaglandin-Endoperoxide Synthases; Safflower Oil; Transfection; Triglycerides

The relationship between growth and alterations in arachidonic acid (AA) metabolism in human breast (MCF-7) and colon (SW480) cancer cells was studied. Four different fatty acid preparations were evaluated: a mixture of conjugated linoleic acid (CLA) isomers (c9,t11, t10,c12, c11,t13, and minor amounts of other isomers), the pure c9,t11-CLA isomer, the pure t10,c12-CLA isomer, and linoleic acid (LA) (all at a lipid concentration of 16 microg/mL). 14C-AA uptake into the monoglyceride fraction of MCF-7 cells was significantly increased following 24 h incubation with the CLA mixture (P < 0.05) and c9,t11-CLA (P < 0.02). In contrast to the MCF-7 cells, 14C-AA uptake into the triglyceride fraction of the SW480 cells was increased while uptake into the phospholipids was reduced following treatment with the CLA mixture (P < 0.02) and c9,t11-CLA (P < 0.05). Distribution of 14C-AA among phospholipid classes was altered by CLA treatments in both cell lines. The c9,t11-CLA isomer decreased (P < 0.05) uptake of 14C-AA into phosphatidylcholine while increasing (P < 0.05) uptake into phosphatidylethanolamine in both cell lines. Both the CLA mixture and the t10,c12-CLA isomer increased (P < 0.01) uptake of 14C-AA into phosphatidylserine in the SW480 cells but had no effect on this phospholipid in the MCF-7 cells. Release of 14C-AA derivatives was not altered by CLA treatments but was increased (P < 0.05) by LA in the SW480 cell line. The CLA mixture of isomers and c9,t11-CLA isomer inhibited 14C-AA conversion to 14C-prostaglandin E2 (PGE2) by 20-30% (P < 0.05) while increasing 14C-PGF2alpha by 17-44% relative to controls in both cell lines. LA significantly (P < 0.05) increased 14C-PGD2 by 13-19% in both cell lines and increased 14C-PGE2 by 20% in the SW480 cell line only. LA significantly (P < 0.05) increased 5-hydroperoxyeicosatetraenoate by 27% in the MCF-7 cell line. Lipid peroxidation, as determined by increased levels of 8-epi-prostaglandin F2alpha (8-epi-PGF2alpha), was observed following treatment with c9,t11-CLA isomer in both cell lines (P < 0.02) and with t10,c12-CLA isomer in the MCF-7 cell line only (P < 0.05). These data indicate that the growth-promoting effects of LA in the SW480 cell line may be associated with enhanced conversion of AA to PGE2 but that the growth-suppressing effects of CLA isomers in both cell lines may be due to changes in AA distribution among cellular lipids and an altered prostaglandin profile.

Topics: Arachidonic Acid; Breast Neoplasms; Carbon Radioisotopes; Cell Survival; Colonic Neoplasms; Dinoprost; Dinoprostone; Humans; Leukotriene B4; Leukotrienes; Linoleic Acid; Prostaglandin D2; Tumor Cells, Cultured

Conjugated linoleic acid (CLA) is a potent inhibitor of the initiation and promotion of mammary carcinogenesis in animal models, but its role in colon carcinogenesis remains unclear. The objective of this study was to determine whether CLA inhibits the promotion of colon carcinogenesis. Forty male Sprague-Dawley rats were given a single dose of azoxymethane (20 mg/kg body wt i.p.). After 1 wk, the animals were randomized into two groups (n = 20) and fed a control AIN-93G diet or the control diet supplemented with 1% CLA at the expense of the soybean oil. After 12 wk, the animals were killed, and their colons were stained with methylene blue for aberrant crypt foci (ACF) analysis by light microscopy. The total number of ACF per animal did not differ between the control (174 +/- 11) and CLA (170 +/- 10) groups. Furthermore, CLA did not affect the average crypt multiplicity (crypts/ACF) or the average number of ACF in any size category. However, rats fed the 1% CLA diet had significantly higher serum insulin levels at the time of sacrifice than those fed the control diet. Thus it is possible that the promoting effects of elevated serum insulin on colon carcinogenesis may have counteracted an inhibitory effect of CLA.

Topics: Animals; Azoxymethane; Colon; Colonic Neoplasms; Insulin; Linoleic Acid; Male; Precancerous Conditions; Rats; Rats, Sprague-Dawley

We previously found (I. Shureiqi et al., Carcinogenesis (Lond.), 20: 1985-1995, 1999; I. Shureiqi et al, J. Natl. Cancer Inst., 92: 1136-1142, 2000) that (a) 15-lipoxygenase-1 (15-LOX-1) protein and its product 13-S-hydroxyoctadecadienoic acid (13-S-HODE) are decreased; and (b) nonsteroidal anti-inflammatory drug (NSAID)-induced 15-LOX-1 expression is critical to NSAID-induced apoptosis in colorectal cancer cells expressing cyclooxygenase-2 (COX-2). We used the NSAIDs sulindac sulfone (COX-2-independent) and NS-398 (a COX-2 inhibitor) to assess NSAID upregulation of 15-LOX-1 in relation to COX-2 inhibition during NSAID-induced apoptosis in the DLD-1 (COX-2-negative) colon cancer cell line. We found that: (a) NSAIDs up-regulated 15-LOX-1, which preceded apoptosis; and (b) 15-LOX-1 inhibition blocked NSAID-induced apoptosis, which was restored by 13-S-HODE but not by its parent, linoleic acid. NSAIDs can induce apoptosis in colon cancer cells via up-regulation of 15-LOX-1 in the absence of COX-2.

Topics: Anti-Inflammatory Agents, Non-Steroidal; Antineoplastic Agents; Antioxidants; Antithrombins; Apoptosis; Arachidonate 15-Lipoxygenase; Arachidonic Acid; Blotting, Western; Caffeic Acids; Cell Line; Colonic Neoplasms; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Humans; Hydroxyeicosatetraenoic Acids; Isoenzymes; Linoleic Acid; Linoleic Acids; Membrane Proteins; Nitrobenzenes; Prostaglandin-Endoperoxide Synthases; Recombinant Proteins; Sulfonamides; Sulindac; Time Factors; Tumor Cells, Cultured; Up-Regulation

The cooking of meat and fish produces heterocyclic amine mutagens, including 2-amino-1-methyl-6-phenylimidazo[4,5b]pyridine (PhIP) and 2-amino-3-methylimidazo[4,5-f]quinoline (IQ). Chronic administration of PhIP or IQ to the F344 rat induces tumors at several sites, including adenocarcinomas of the colon, and short-term treatment leads to the formation of colonic aberrant crypt foci (ACF). We have used these end-points to identify potential chemopreventive agents that might be effective against heterocyclic amine colon carcinogens. Typically, IQ or PhIP were administered to groups of 10-15 rats by oral gavage on alternating days in weeks 3 and 4, and ACF were scored after 8, 12, or 16 weeks or tumors were detected at 52 weeks. To distinguish between 'blocking' and 'suppressing' agents, potential inhibitors were administered during the initiation or post-initiation phases, respectively, and subsequent studies focused on the inhibitory mechanisms. Among the most effective inhibitors identified to date, and their major mechanisms, were the following: chlorophyllin (molecular complex formation); indole-3-carbinol (inhibition and induction of cytochromes P450 and phase II enzymes); green and black tea catechins (induction of UDP-glucuronosyl transferase, inhibition of NADPH-cytochrome P450 reductase, scavenging of reactive intermediates); and conjugated linoleic acids (inhibition of cytochrome P450 and prostaglandin H synthase).

Topics: Animals; Anticarcinogenic Agents; Carcinogens; Catechin; Chlorophyllides; Colon; Colonic Neoplasms; Drug Antagonism; Imidazoles; Indoles; Linoleic Acid; Precancerous Conditions; Quinolines; Rats; Rats, Inbred F344

This study examined the effect of n-6 polyunsaturated fatty acids (PUFAs) on the expression of nm-23, a metastasis-suppressor gene, in two highly invasive human cancer cell lines, HT115 and MDA MB 231. A range of n-6 and n-3 PUFAs were tested. We report that while linoleic acid and arachidonic acid reduced the expression of nm-23-H1, gamma linolenic acid (GLA) and its soluble lithium salt markedly increased the expression of the molecules. The stimulation of the expression of nm-23 by GLA was seen at both protein and mRNA levels. Up-regulation of nm-23 was also associated with a reduction of the in vitro invasiveness of these cells. It is concluded that gamma linolenic acid (GLA) enhances the expression of nm-23. This contributes to the inhibition of the in vitro invasion of tumour cells.

Topics: Arachidonic Acid; Breast Neoplasms; Colonic Neoplasms; Drug Screening Assays, Antitumor; Eicosapentaenoic Acid; gamma-Linolenic Acid; Gene Expression Regulation, Neoplastic; Humans; Linoleic Acid; Monomeric GTP-Binding Proteins; Neoplasm Invasiveness; Neoplasm Proteins; NM23 Nucleoside Diphosphate Kinases; Nucleoside-Diphosphate Kinase; RNA, Messenger; RNA, Neoplasm; Transcription Factors; Tumor Cells, Cultured

Topics: Breast Neoplasms; Colonic Neoplasms; Dietary Fats, Unsaturated; Female; Humans; Linoleic Acid; Male; Prostatic Neoplasms

The effects of eicosapentaenoic acid [EPA; n-3 polyunsaturated fatty acid (PUFA)], linoleic acid (LA; n-6 PUFA), and palmitic acid (PA; saturated fatty acid) on 1,2-dimethylhydrazine-induced F344 rat colon carcinoma cells (ACL-15) were investigated in vivo and in vitro. The number and size of liver metastatic foci via a superior mesenteric vein injection of ACL-15 cells in F344 rats were significantly inhibited in the EPA-treated group compared with the LA-treated group (p < 0.01); the PA-treated animals and those fed commercial rodent chow (standard diet) demonstrated intermediate values. In a dot immunoblotting assay, vascular cell adhesion molecule 1 expression on ACL-15 cells was downregulated by EPA-ethyl ester treatment and upregulated by LA-ethyl ester treatment compared with the untreated control cells, whereas the expression of matrix metalloproteinase 1 and 2 was not influenced by the fatty acid ethyl esters. In a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, EPA-ethyl ester suppressed ACL-15 cell growth in a schedule-dependent manner, and LA-ethyl ester showed schedule-dependent stimulation. In contrast, PA demonstrated no regulatory effect on cell growth at lower concentrations (< or = 5 mg/ml) but concentration-dependent inhibition at higher concentrations. According to our in vivo cell kinetic study, the difference in tumor growth at the metastatic site was due to different tumor cell proliferation rates; the cell loss rate was not altered. Therefore, the inhibitory effect of liver metastasis on ACL-15 cells by EPA can be explained by a decreased ability of tumor cell adhesion to the capillary bed (low expression of vascular cell adhesion molecule 1) and a lower potential of tumor cell proliferation (low mitotic rate) at the secondary site.

Topics: Animals; Colonic Neoplasms; Dietary Fats; Eicosapentaenoic Acid; Fatty Acids; Linoleic Acid; Liver Neoplasms; Male; Palmitic Acid; Rats; Rats, Inbred F344; Tumor Cells, Cultured

Animal and ecological studies suggest that linoleic acid intake is related to breast-cancer incidence. Analytical epidemiologic studies, however, do not support such findings. The primary objective of our ecological study was to investigate the association between breast-cancer incidence and linoleic acid status across European countries. In addition, other fatty acids and cancer sites were studied. Mean fatty acid composition of adipose tissue samples in 11 centres from 8 European countries and Israel served as indicators of exposure of the population. Figures on cancer incidence for the respective or comparable regions were obtained from published data. N-6 fatty acids in adipose tissue ranged from 10.4 in Helsinki to 24.6 g/100 g fatty acids in Jerusalem. N-6 fatty acids were not associated significantly with breast, colon or prostate cancer. Cancers of the breast and colon were associated negatively with cis-mono-unsaturated fatty acids and positively with trans fatty acids. Despite a large range in intake, we found no evidence of a positive association between n-6 fatty acid status and breast cancer, but associations were observed between other fatty acids and cancer. Differences in linoleic acid intake cannot explain risk differences in breast-cancer incidence between affluent countries, while associations of other fatty acids with cancer rates may reflect cultural differences.

Topics: Adipose Tissue; Aged; Biomarkers, Tumor; Breast Neoplasms; Case-Control Studies; Colonic Neoplasms; Europe; Fatty Acids; Fatty Acids, Omega-3; Fatty Acids, Omega-6; Fatty Acids, Unsaturated; Female; Humans; International Cooperation; Israel; Linoleic Acid; Linoleic Acids; Male; Middle Aged; Prostatic Neoplasms; Risk Factors

2,3,5-Trimethyl-6-(3-pyridylmethyl)1,4-benzoquinone (CV-6504), an inhibitor of 5-lipoxygenase and thromboxane A2 synthase and a scavenger of active oxygen species, has been shown to exhibit profound anti-tumour activity against three established murine adenocarcinomas (MACs) that are generally refractory to standard cytotoxic agents. For the cachexia-inducing MAC16 tumour, optimal anti-tumour activity was seen at dose levels of 10 and 25 mg kg-1 day-1, together with a reversal of cachexia and a doubling of the time to sacrifice of the animals through cachexia from 8 days to 17 days. The remaining tumour fragments showed extensive necrosis in regions distal from the blood supply. Growth of the MAC13 tumour was also effectively suppressed at dose levels between 5 and 50 mg kg-1 day-1, resulting in a specific growth delay between 1.0 and 1.2. Growth of the MAC26 tumour was also inhibited a concentration-related manner, with doses of 25-50 mg kg-1 day-1 being optimal. Anti-tumour activity towards all three tumours at low dose levels of CV-6504 was effectively suppressed by concurrent administration of linoleic acid (1 g kg-1 day-1), suggesting that inhibition of linoleate metabolism was responsible for the anti-tumour effect. Tumour sensitivity may be correlated with increased DT-diaphorase that are required to metabolise CV-6504 to the active hydroquinone, which inhibits 5-lipoxygenase activity.

Topics: Adenocarcinoma; Administration, Oral; Animals; Antineoplastic Agents; Benzoquinones; Cell Division; Colonic Neoplasms; Growth Inhibitors; Linoleic Acid; Linoleic Acids; Lipoxygenase Inhibitors; Male; Mice; Mice, Inbred Strains

Polarized monolayers of intestinal Caco-2 cells were used to study the effects of saturated palmitic acid (16:0) and polyunsaturated linoleic acid (18:2) on triglyceride synthesis and lipoprotein secretion. Monolayers were incubated for 24 h, at the apical or lumenal side, with palmitic acid (16:0) or linoleic acid (18:2) in physiological concentrations. Incubation with 1.0 mM 16:0 or 18:2 resulted in differences in the composition and amount of secreted lipoproteins. Radiolabeled lipids in the lipoproteins secreted during incubation with 18:2 were found in the chylomicron/VLDL (very low density lipoprotein) density whereas with 16:0 the secreted lipoproteins were in the intermediate density/low density lipoprotein (IDL/LDL) density range. More triglyceride was secreted into the (basolateral) medium during incubation with 1.0 mM 18:2 (41 +/- 12% of total triglyceride synthesized) than with 1.0 mM 16:0 (18 +/- 3% of total). The biochemical findings correlate with conspicuous morphological changes in the cells in the presence of 16:0, but not 18:2. Increasing concentrations of 16:0 (0.1-1.0 mM) caused gradual accumulation of intracellular membrane. Microvilli became strongly reduced in number. With 1.0 mM palmitic acid we found an increased incorporation of [1-14C]palmitic acid into phosphatidic acid (14.8% of total incorporation into phospholipid with 16:0 vs. < 0.5% with 18:2) and diacylglycerol (12.5% with 16:0 vs. < 0.5% with 18:2) and diacylglycerol (12.5% with 16:0 vs. 0.5% with 18:2) and the amount of intracellular phospholipid doubled. The morphological changes were completely reversed after 24 h with 1.0 mM 18:2. We conclude from our results that, compared to 18:2, 16:0 is not efficiently incorporated into triglycerides. 16:0 is incorporated into cellular phospholipids in a greater proportion than 18:2, causing accumulation of intracellular phospholipid and the precursors phosphatidic acid and diacylglycerol. Different processing of 18:2 and 16:0 by Caco-2 cells resulted in profound differences in triglyceride synthesis and lipoprotein composition and secretion.

Topics: Carbon Radioisotopes; Cell Line; Centrifugation, Density Gradient; Colonic Neoplasms; Fatty Acids; Humans; Immunoblotting; Intestinal Mucosa; Intestines; Linoleic Acid; Linoleic Acids; Lipoproteins; Microscopy, Electron; Palmitic Acid; Palmitic Acids; Particle Size; Triglycerides; Tumor Cells, Cultured

In this study we have determined the effects of the n-6 essential fatty acid gamma-linolenic acid (GLA) on the motility and invasive/metastatic nature of the human colon cancer cell lines HT115, HT29 and HRT18. Cell motility was induced by hepatocyte growth factor/scatter factor (HGF/SF) and measured by both colony scattering and dissociation from carrier beads. Invasiveness was measured in vitro by cellular invasion into extracellular matrix. At concentrations up to 100 microM (which had no effect on cell growth over the duration of the experiments) both cell motility and invasion induced by HGF/SF were markedly reduced by GLA and its lithium salt. The attachment of these cells to the extracellular matrix components (Matrigel and fibronectin) was also inhibited. There were also changes in the cell-surface E-cadherin, but not fibronectin receptor at similar concentrations. It is concluded that n-6 essential fatty acids have the ability to inhibit both motility and invasiveness of human colon cancer cells, perhaps by modifying cell-surface adhesion molecules.

Topics: Arachidonic Acid; Cadherins; Cell Adhesion; Cell Line; Cell Movement; Colonic Neoplasms; Extracellular Matrix; gamma-Linolenic Acid; Hepatocyte Growth Factor; Humans; Linoleic Acid; Linoleic Acids; Neoplasm Invasiveness; Receptors, Fibronectin; Tumor Cells, Cultured

Grilled ground beef contains a number of heterocyclic amine carcinogens, such as 2-amino-3-methylimidazo[4,5-f] quinoline (IQ), as well as anticarcinogenic conjugated linoleic acids (CLA). In the present study, CLA was administered to male F344 rats by gavage on alternating days in weeks 1-4, while IQ was given by gavage every other day in weeks 3 and 4 (100 mg/kg body wt). Rats were killed 6 h after the final carcinogen dose 16 in order to score colonic aberrant crypt foci (ACF). In the ACF study, CLA had no effect on the size of the foci, but inhibited significantly (P < 0.05) the number of ACF/colon, from 4.3 +/- 2.4 in controls to 1.1 +/- 1.3 in CLA-treated rats (mean +/- SD, n = 10). Rats given CLA also had significantly lower IQ-DNA adducts in the colon as determined by 32P-postlabeling analysis; relative adduct labeling levels (RAL x 10(7) for the major adduct were 9.13 +/- 2.6 in controls versus 5.42 +/- 1.8 in CLA-treated animals (P < 0.05). Mechanism studies indicated that CLA and other fatty acids interact with certain heterocyclic amines in a manner consistent with substrate-ligand binding. However, no such interaction occurred with IQ, and CLA failed to inhibit significantly the mutagenicity of N-hydroxy-IQ in the Salmonella assay. Liver microsomes from CLA-treated rats exhibited lower activities for dealkylation of 7-ethoxyresorufin and methoxyresorufin and activated IQ to DNA binding species less effectively than microsomes from control animals. Direct addition of CLA to the in vitro incubation inhibited IQ-DNA binding and was associated with increased recovery of unmetabolized parent compound. In the Salmonella assay, CLA inhibited the mutagenic activity of IQ in the presence of S9 or ram seminal vesicle microsomes. Collectively, these results support a mechanism involving inhibition of carcinogen activation by CLA, as opposed to direct interaction with the procarcinogen, scavenging of electrophiles or selective induction of phase I detoxification pathways.

Topics: Animals; Anticarcinogenic Agents; Antimutagenic Agents; Carcinogens; Colonic Neoplasms; DNA Adducts; Enzyme Induction; Linoleic Acid; Linoleic Acids; Male; NADH, NADPH Oxidoreductases; NADPH-Ferrihemoprotein Reductase; Quinolines; Rats; Rats, Inbred F344; Substrate Specificity

The effect of the polyunsaturated fatty acids (PUFAs) linoleic acid (LA) and arachidonic acid (AA) on the growth of two murine colon adenocarcinoma cell lines (MAC26 and MAC13) has been determined both in vitro and in vivo. When the serum concentrations in the medium became growth limiting, low concentrations (18-33 microM) of both PUFAs were growth stimulatory to both cell lines, while higher concentrations were growth inhibitory. Growth stimulation by AA in both cell lines, and by LA in MAC13, was effectively inhibited by both the cyclo-oxygenase and lipoxygenase inhibitor indomethacin, and the lipoxygenase inhibitor BWA4C in a dose-dependent manner. The most effective inhibition was exerted by BWA4C, suggesting metabolism of both PUFAs through the lipoxygenase pathway for growth stimulation. In vivo studies using the MAC26 tumour showed a significant stimulation of tumour growth when LA was administered orally at concentrations higher than 0.4 g kg-1 day-1. Higher concentrations did not produce a further increase in tumour growth rate. This suggests that there is a threshold dose for growth stimulation by LA which, together with that in the diet, amounted to 3.8% of the total caloric intake. The increase in tumour volume induced by LA arose from a reduction in the potential doubling time from 41 to 28 h and was effectively reversed by indomethacin (5 mg kg-1). These results suggest that PUFAs may play an important role in tumour growth and may offer a potential target for the development of chemotherapeutic agents.

Topics: Adenocarcinoma; Analysis of Variance; Animals; Arachidonic Acid; Benzeneacetamides; Cell Division; Colonic Neoplasms; Cyclooxygenase Inhibitors; Dietary Fats, Unsaturated; Dose-Response Relationship, Drug; Hydroxamic Acids; Indomethacin; Linoleic Acid; Linoleic Acids; Lipoxygenase Inhibitors; Male; Mice; Mice, Inbred Strains; Tumor Cells, Cultured

Oral administration of eicosapentaenoic acid (EPA) (2.0 g/kg) by gavage to female NMRI mice bearing the MAC16 colon adenocarcinoma and with weight loss, prevented further loss in body weight and produced a delay in the growth of the tumour. Cell production and loss were determined by the [125I]5-iodo-2'-deoxyuridine method during the stationary and growth phase of the tumour in animals treated with EPA. Tumour stasis appeared to arise from an increase in the rate of cell loss from 38 to 71% without a significant change in the potential doubling time. During the subsequent growth phase the cell loss factor was reduced to 52% and this was combined with a reduced potential doubling time from 32 to 26 hr. The antiproliferative, but not the anticachectic effect of EPA could be reversed by oral administration of pure linoleic acid (LA), (1.9 g/kg) which acted to increase tumour growth by reducing the cell loss factor to 45%. Despite this reversal, incorporation of EPA into tumour cell lipids was not significantly different in animals administered with either EPA alone or combined with LA. This suggests that the antiproliferative effect of EPA in this system may arise from an indirect effect through the blocking of the catabolic effect of the tumour on host adipose tissue, which normally supplies fatty acids essential for tumour growth. This suggests that LA may be required by some tumours to prevent cell loss and that the catabolism of adipose tissue, which accompanies cancer cachexia effectively supplies this fatty acid to the tumour.

Topics: Adenocarcinoma; Animals; Body Weight; Cell Cycle; Colonic Neoplasms; Eicosapentaenoic Acid; Fatty Acids; Female; Linoleic Acid; Linoleic Acids; Lipids; Mice; Tumor Cells, Cultured

The growth-promoting effect of several hormones and growth factors on eight human colon tumor cell lines (SW 48, SW 403, SW 480, SW 620, SW 948, HT29, LS174T and Caco-2) was studied using seven different chemically defined serum-free media [GF3: Chee's essential medium plus insulin, transferrin and selenium; GF3F: GF3 plus fetuin; GF4: GF3 plus linoleic acid/bovine-serum albumin (BSA); GF5: GF4 plus fetuin, GF5E, GF5 plus EGF; GF5T: GF5 plus triiodothyronine; GF7: GF3 plus EGF, transferrin, insulin, linoleic acid/BSA, oleic acid/BSA and fetuin]. GF5 appears to be the best serum-free medium as it supported continuous growth of all of the colon tumor cell lines. GF5 also supported growth of five of the seven human colon and stomach tumor xenografts as primary tissue cultures. However, the stomach xenograft cells had a very slow growth rate as compared to the colon xenograft cells in the medium. Cells grown in GF5 retained their tumorigenicity in athymic (nude) mice and characteristic cellular morphology. GF7 was the poorest of all of the serum-free media studied as none of the cell lines or xenografts grew in this medium.

Topics: Adenocarcinoma; alpha-Fetoproteins; Cell Division; Cell Line; Colonic Neoplasms; Culture Media, Serum-Free; Culture Techniques; Epidermal Growth Factor; Humans; Insulin; Linoleic Acid; Linoleic Acids; Neoplasm Transplantation; Oleic Acid; Oleic Acids; Transferrin; Triiodothyronine; Tumor Cells, Cultured

The effects of dietary unsaturated and saturated fats on chemically induced colon carcinogenesis were examined in male Donryu rats. The rats were fed two types of semipurified diets consisting of 5% linoleic acid or 4.7% stearic acid plus 0.3% essential fatty acid as dietary fats. The rats were treated with azoxymethane (7.4 mg/kg body weight) s.c. once a week for 11 weeks and sacrificed 15 weeks after the last injection of the carcinogen. The rats fed unsaturated fat diet demonstrated a significantly higher incidence of colon tumors [100%], more tumors per rat [2.68 +/- 1.60 (S.D.)], and greater malignant differentiation histologically than did those fed saturated fat diet [76%, 1.79 +/- 1.59, respectively]. Lipid analysis of colon tumors and colon mucosa showed that unsaturated fat diet altered the phosphatide fatty acyl composition of colon mucosa markedly and increased the content of arachidonic acid in the neutral lipid of colon tumors. The altered lipid composition of the mucosa may increase the sensitivity of the colon to the carcinogen, and the excess of arachidonic acid or its metabolites may be the primary agents of cocarcinogenesis of colon tumors. These findings suggest that dietary unsaturated fats have potent cocarcinogenic effects on colon carcinogenesis.

Topics: Animals; Azoxymethane; Body Weight; Colon; Colonic Neoplasms; Dietary Fats; Fatty Acids; Intestinal Mucosa; Linoleic Acid; Linoleic Acids; Liver; Male; Phospholipids; Rats; Rats, Inbred Strains; Stearic Acids