4-hydroxy-2-nonenal and Colorectal-Neoplasms

4-hydroxy-2-nonenal (HNE) is an amazing reactive compound, originating from lipid peroxidation within cells but also in food and considered as a "second messenger" of oxidative stress. Due to its chemical features, HNE is able to make covalent links with DNA, proteins and lipids. The aim of this review is to give a comprehensive summary of the chemical properties of HNE and of the consequences of its reactivity in relation to cancer development. The formation of exocyclic etheno-and propano-adducts and genotoxic effects are addressed. The adduction to cellular proteins and the repercussions on the regulation of cell signaling pathways involved in cancer development are reviewed, notably on the Nrf2/Keap1/ARE pathway. The metabolic pathways leading to the inactivation/elimination or, on the contrary, to the bioactivation of HNE are considered. A special focus is given on the link between HNE and colorectal cancer development, due to its occurrence in foodstuffs and in the digestive lumen, during digestion.

Topics: Aldehydes; Carcinogenesis; Colon; Colorectal Neoplasms; DNA Adducts; Gene Expression Regulation, Neoplastic; Humans; Inflammatory Bowel Diseases; Kelch-Like ECH-Associated Protein 1; Mitogen-Activated Protein Kinases; NF-E2-Related Factor 2; Oxidation-Reduction; Oxidative Stress; Precancerous Conditions; Protein Kinase C; Signal Transduction

Consistent experimental data suggest the importance of inflammation-associated oxidative stress in colorectal cancer (CRC) pathogenesis. Inflammatory bowel disease with chronic intestinal inflammation is now considered a precancerous condition. Oxidative stress is an essential feature of inflammation. Activation of redox-sensitive pro-inflammatory cell signals and inflammatory mediators concur to establish a pro-tumoral environment. In this frame, lipid oxidation products, namely 4-hydroxynonenal and oxysterols, can be produced in big quantity so as to be able to exert their function as inducers of cell signaling pathways of proliferation and survival. Notably, an important source of these two compounds is represented by a high fat diet, which is undoubtedly a risk factor for inflammation and CRC development. Current evidence for the emerging implication of these two oxidized lipids in inflammation and CRC development is discussed in this review.

Topics: Aldehydes; Carcinogenesis; Cholesterol; Colon; Colorectal Neoplasms; Diet, High-Fat; Gene Expression Regulation, Neoplastic; Humans; Inflammation; Inflammatory Bowel Diseases; NF-kappa B; Oxidation-Reduction; Oxidative Stress; Oxysterols; Risk Factors; Signal Transduction; STAT3 Transcription Factor

The review aims at elucidating the role of lipid peroxidation of polyunsaturated fatty acids (PUFAs) in colorectal cancer (CRC) risk and treatment.. CRC is one of the most overriding threats to public health. Despite a broad range of treatments, up to 50% of patients will inevitably develop incurable metastatic disease. Peroxidation of PUFAs contributes to augmentation of oxidative stress and causes in consequence inflammation, which is one of the possible carcinogenic factors of CRC. End products of PUFAs might be used as biomarkers for CRC detection and surveillance for treatment. They also have cytotoxic effect in CRC cells. Experimental results suggest that ω-3 PUFAs could increase the efficacy of radiotherapy and chemotherapy of CRC.. Lipid peroxidation, one factor of oxidative stress, might play a paramount role not only in carcinogenesis but also in potential therapeutic strategy on CRC. End products of lipid peroxidation, such as malondialdehyde, 4-hydroxy-2-nonenal, and isoprostanes, could be used as biomarkers for cancer detection, surveillance of treatment outcome and prognostic index for CRC patients. Furthermore, malondialdehyde and 4-hydroxy-2-nonenal have cytotoxic effect not only in normal cells but also in CRC cancer cells, which implies the potential role of PUFAs in CRC treatment.

Topics: Aldehydes; Biomarkers; Colorectal Neoplasms; Fatty Acids, Unsaturated; Humans; Isoprostanes; Lipid Peroxidation; Malondialdehyde; Oxidative Stress; Risk Factors; Treatment Outcome

To assess the association of the expression of apolipoprotein B (apoB) and 4-hydroxynonenal (4HNE) with the clinicopathological data of patients with colorectal cancer (CRC).. We obtained 80 CRC histopathological specimens sent to the Pathology Laboratory of Hospital Universiti Sains Malaysia from 2015 to 2019. Data on demographic factors, body mass index (BMI), and clinicopathological characteristics were also collected. Formalin-fixed paraffin-embedded tissues were stained by using an optimized immunohistochemical protocol.. Patients were mostly older than 50 years, male, Malay, and overweight or obese. A high apoB expression was observed in 87.5% CRC samples (70/80), while a high 4HNE expression was observed in only 17.5% (14/80) of CRCs. The expression of apoB was significantly associated with the sigmoid and rectosigmoid tumor sites (p =0.001) and tumor size 3-5 cm (p =0.005). 4HNE expression was significantly associated with tumor size 3-5 cm (p =0.045). Other variables were not significantly associated with the expression of either marker.. ApoB and 4HNE proteins may play a role in promoting CRC carcinogenesis.

Topics: Aldehydes; Apolipoproteins B; Colorectal Neoplasms; Humans; Male; Middle Aged; Retrospective Studies

Electrophilic carbonyl compounds are highly cytotoxic and genotoxic. Aldo-keto reductase 1B10 (AKR1B10) is an enzyme catalyzing reduction of carbonyl compounds to less toxic alcoholic forms. This study presents novel evidence that AKR1B10 protects colon cells from DNA damage induced by electrophilic carbonyl compounds. AKR1B10 is specifically expressed in epithelial cells of the human colon, but this study found that AKR1B10 expression was lost or markedly diminished in colorectal cancer, precancerous tissues, and a notable portion of normal adjacent tissues (NAT). SiRNA-mediated silencing of AKR1B10 in colon cancer cells HCT-8 enhanced cytotoxicity of acrolein and HNE, whereas ectopic expression of AKR1B10 in colon cancer cells RKO prevented the host cells against carbonyl cytotoxicity. Furthermore, siRNA-mediated AKR1B10 silencing led to DNA breaks and activation of γ-H2AX protein, a marker of DNA double strand breaks, particularly in the exposure of HNE (10 μM). In the AKR1B10 silenced HCT-8 cells, hypoxanthine-guanine phosphoribosyl transferase (HPRT) mutant frequency increased by 26.8 times at basal level and by 33.5 times in the presence of 10 μM HNE when compared to vector control cells. In these cells, the cyclic acrolein-deoxyguanosine adducts levels were increased by over 10 times. These findings were confirmed by pharmacological inhibition of AKR1B10 activity by Epalrestat. Taken together, these data suggest that AKR1B10 is a critical protein that protects host cells from DNA damage induced by electrophilic carbonyl compounds. AKR1B10 deficiency in the colon may be an important pathogenic factor in disease progression and carcinogenesis. © 2016 Wiley Periodicals, Inc.

Topics: Acrolein; Aldehyde Reductase; Aldehydes; Aldo-Keto Reductases; Cell Line, Tumor; Colon; Colorectal Neoplasms; DNA Damage; Gene Silencing; Humans; Mutagens; Rectum

Epidemiological studies have associated red meat intake with risk of colorectal cancer. Experimental studies explain this positive association by the oxidative properties of heme iron released in the colon. This latter is a potent catalyst for lipid peroxidation, resulting in the neoformation of deleterious aldehydes in the fecal water of heme-fed rats. The toxicity of fecal water of heme-fed rats was associated to such lipid peroxidation. This study demonstrated that fecal water of hemoglobin- and beef-fed rats preferentially induced apoptosis in mouse normal colon epithelial cells than in those carrying mutation on Apc (Adenomatous polyposis coli) gene, considered as preneoplastic. Highlighting the importance of lipid peroxidation and neoformation of secondary aldehydes like 4-hydroxy-2-nonenal (HNE), we optimized the depletion of carbonyl compounds in the fecal water which turned out to abolish the differential apoptosis in both cell lines. To explain the resistance of preneoplastic cells towards fecal water toxicity, we focused on Nrf2, known to be activated by aldehydes, including HNE. Fecal water activated Nrf2 in both cell lines, associated with the induction of Nrf2-target genes related to aldehydes detoxification. However, the antioxidant defense appeared to be higher in preneoplastic cells, favoring their survival, as evidenced by Nrf2 inactivation. Taken together, our results suggest that Nrf2-dependent antioxidant response was involved in the resistance of preneoplastic cells upon exposure to fecal water of hemoglobin- and beef-fed rats. This difference could explain the promoting effect of red meat and heme-enriched diet on colorectal cancer, by initiating positive selection of preneoplastic cells.

Topics: Aldehydes; Animals; Antioxidants; Apoptosis; Colon; Colorectal Neoplasms; Feces; Hemoglobins; Inactivation, Metabolic; Male; Mice; NF-E2-Related Factor 2; Precancerous Conditions; Rats, Inbred F344; Red Meat

Glutathione S-transferase alpha 4 (GSTA4) is a phase II detoxifying enzyme that metabolizes electrophiles and carcinogens including 4-hydroxy-2-nonenal (4-HNE), an endogenous carcinogen that contributes to colorectal carcinogenesis. In this study, we investigated GSTA4 expression and regulation in murine primary colonic epithelial cells, microbiome-driven murine colitis and human carcinomas. Exposure of YAMC cells to 4-HNE induced Gsta4 expression. Using an inflammation-associated model of colorectal cancer (CRC), Gsta4 expression increased in vivo in colon macrophages and serum after 2 weeks of colonization of IL-10 deficient (Il10

Topics: Aldehydes; Animals; Base Sequence; Binding Sites; Cell Line, Tumor; Colorectal Neoplasms; Disease Models, Animal; Epithelial Cells; Gene Expression; Gene Expression Regulation, Neoplastic; Glutathione Transferase; Humans; Immunohistochemistry; Intestinal Mucosa; Mice; Mice, Knockout; Models, Biological; NF-E2-Related Factor 2; Protein Binding; Proto-Oncogene Proteins c-jun; Transcription Factor AP-1

Protein alkylation by 4-hydroxy-2-nonenal (HNE), an endogenous lipid derived electrophile, contributes to stress signaling and cellular toxicity. Although previous work has identified protein targets for HNE alkylation, the sequence specificity of alkylation and dynamics in a cellular context remain largely unexplored. We developed a new quantitative chemoproteomic platform, which uses isotopically tagged, photocleavable azido-biotin reagents to selectively capture and quantify the cellular targets labeled by the alkynyl analogue of HNE (aHNE). Our analyses site-specifically identified and quantified 398 aHNE protein alkylation events (386 cysteine sites and 12 histidine sites) in intact cells. This data set expands by at least an order of magnitude the number of such modification sites previously reported. Although adducts formed by Michael addition are thought to be largely irreversible, we found that most aHNE modifications are lost rapidly in situ. Moreover, aHNE adduct turnover occurs only in intact cells and loss rates are site-selective. This quantitative chemoproteomics platform provides a versatile general approach to map bioorthogonal-chemically engineered post-translational modifications and their cellular dynamics in a site-specific and unbiased manner.

Topics: Aldehydes; Alkylation; Chromatography, Liquid; Colorectal Neoplasms; Cross-Linking Reagents; Humans; Neoplasm Proteins; Protein Processing, Post-Translational; Tandem Mass Spectrometry; Tumor Cells, Cultured

Opuntia species have been used for thousands of years as a folk medicine in the treatment of diseases. However, the components and protective mechanisms are still unclear. We make the hypothesis that Opuntia species may protect the development of oxidative stress-associated diseases, such as atherosclerosis or colon cancer, via their antioxidant properties. We investigated the protective effect of Opuntia cladode powder against the oxidation of low-density lipoprotein (LDL) evoked by vascular endothelial cells, an important risk factor for atherosclerosis development, and the toxicity of 4-hydroxynonenal (a major lipid peroxidation product) on normal (Apc +/+) and preneoplastic (Apc min/+) immortalized epithelial colon cells. Various Opuntia species classified according to their degree of domestication, from the wildest (Opuntia streptacantha, Opuntia hyptiacantha, Opuntia megacantha), medium (Opuntia albicarpa), to the most domesticated (Opuntia ficus-indica) were tested. Cladode powders prepared from these Opuntia species significantly inhibited LDL oxidation induced by incubation with murine endothelial cells and the subsequent foam cell formation of RAW 264.7 murine macrophages and cytotoxicity on murine endothelial cells. Moreover, Opuntia cladode powder blocked the promotion of colon cancer development on an in vitro model of colonocytes. It may be noted that the phenolic acid and flavonoids content, the antioxidant capacity, and the protective effect were relatively similar in all the cladode powders from wild (O. streptacantha) and domesticated Opuntia. Altogether, these data confirm the therapeutic potential of Opuntia cladodes in diseases associated with oxidative stress.

Topics: Aldehydes; Animals; Anticarcinogenic Agents; Colorectal Neoplasms; Endothelial Cells; Endothelium, Vascular; Lipid Peroxidation; Lipoproteins, LDL; Mice, Inbred C57BL; Opuntia; Oxidation-Reduction; Plant Extracts

Uncured and nitrite-cured pork were subjected, raw, cooked (65 °C, 15 min) or overcooked (90 °C, 30 min), to an in vitro digestion model, which includes mouth, stomach, duodenum, and colon phases. Heating of uncured meat resulted in a pronounced increase in lipid and protein oxidation products throughout digestion. Nitrite-curing had an antioxidant effect during digestion, but this effect disappeared when the meat was overcooked, resulting in up to ninefold higher 4-hydroxy-2-nonenal concentrations compared with digested nitrite-cured raw and cooked pork. Colonic digesta contained significantly higher concentrations of the NOC-specific DNA adduct O(6)-carboxy-methylguanine when pork underwent a more intense heating procedure, independent of nitrite-curing, depending strongly on the fecal inoculum used. Since processed meats are usually nitrite-cured, the present study suggests that overcooking processed meat is likely to result in the formation of genotoxic compounds during digestion and should, therefore, be avoided.

Topics: Aldehydes; Animals; Colon; Colony Count, Microbial; Colorectal Neoplasms; Cooking; Digestion; DNA Adducts; Feces; Gastrointestinal Microbiome; Humans; Nitrites; Nitrosation; Oxidation-Reduction; Red Meat; Swine

Reactive electrophiles produced during oxidative stress, such as 4-hydroxynonenal (HNE), are increasingly recognized as contributing factors in a variety of degenerative and inflammatory diseases. Here we used the RNA-seq technology to characterize transcriptome responses in RKO cells induced by HNE at subcytotoxic and cytotoxic doses. RNA-seq analysis rediscovered most of the differentially expressed genes reported by microarray studies and also identified novel gene responses. Interestingly, differential expression detection at the coding DNA sequence (CDS) level helped to further improve the consistency between the two technologies, suggesting the utility and importance of the CDS level analysis. RNA-seq data analysis combining gene and CDS levels yielded an informative and comprehensive picture of gradually evolving response networks with increasing HNE doses, from cell protection against oxidative injury at low dose, initiation of cell apoptosis and DNA damage at intermediate dose to significant deregulation of cellular functions at high dose. These evolving dose-dependent pathway changes, which cannot be observed by the gene level analysis alone, clearly reveal the HNE cytotoxic effect and are supported by IC50 experiments. Additionally, differential expression at the CDS level provides new insights into isoform regulation mechanisms. Taken together, our data demonstrate the power of RNA-seq to identify subtle transcriptome changes and to characterize effects induced by HNE through the generation of high-resolution data coupled with differential analysis at both gene and CDS levels.

Topics: Aldehydes; Amino Acid Sequence; Cell Line, Tumor; Colorectal Neoplasms; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Humans; Oligonucleotide Array Sequence Analysis; Sequence Analysis, RNA; Transcriptome

Enterococcus faecalis is a human intestinal commensal that produces extracellular superoxide and promotes chromosome instability via macrophage-induced bystander effects. We investigated the ability of 4-hydroxy-2-nonenal (4-HNE), a diffusible breakdown product of ω-6 polyunsaturated fatty acids, to mediate these effects.. 4-HNE was purified from E faecalis-infected macrophages; its genotoxicity was assessed in human colon cancer (HCT116) and primary murine colon epithelial (YAMC) cell lines.. 4-HNE induced G(2)-M cell cycle arrest, led to formation γH2AX foci, and disrupted the mitotic spindle in both cell lines. Binucleate tetraploid cells that formed after incubation with 4-HNE were associated with the activation of stathmin and microtubule catastrophe. Silencing glutathione S-transferase α4, a scavenger of 4-HNE, increased the susceptibility of epithelial cells to 4-HNE-induced genotoxicity. Interleukin-10 knockout mice colonized with superoxide-producing E faecalis developed inflammation and colorectal cancer, whereas colonization with a superoxide-deficient strain resulted in inflammation but not cancer. 4-HNE-protein adducts were found in the lamina propria and macrophages in areas of colorectal inflammation.. 4-HNE can act as an autochthonous mitotic spindle poison in normal colonic epithelial and colon cancer cells. This finding links the macrophage-induced bystander effects to colorectal carcinogenesis.

Topics: Aldehydes; Animals; Autocrine Communication; Biopsy; Bystander Effect; Coculture Techniques; Colon; Colorectal Neoplasms; Disease Models, Animal; DNA Damage; Enterococcus faecalis; Epithelial Cells; G2 Phase Cell Cycle Checkpoints; Glutathione Transferase; Gram-Positive Bacterial Infections; HCT116 Cells; Histones; Humans; Interleukin-10; Macrophages; Mice; Mice, Knockout; RNA Interference; Spindle Apparatus; Stathmin; Tetraploidy; Time Factors; Transfection

Animal and epidemiological studies suggest that dietary heme iron would promote colorectal cancer. Oxidative properties of heme could lead to the formation of cytotoxic and genotoxic secondary lipid oxidation products, such as 4-hydroxy-2(E)-nonenal (HNE). This compound is more cytotoxic to mouse wild-type colon cells than to isogenic cells with a mutation on the adenomatous polyposis coli (APC) gene. The latter thus have a selective advantage, possibly leading to cancer promotion. This mutation is an early and frequent event in human colorectal cancer. To explain this difference, the HNE biotransformation capacities of the two cell types have been studied using radiolabeled and stable isotope-labeled HNE. Apc-mutated cells showed better biotransformation capacities than nonmutated cells did. Thiol compound conjugation capacities were higher for mutated cells, with an important advantage for the extracellular conjugation to cysteine. Both cells types were able to reduce HNE to 4-hydroxynonanal, a biotransformation pathway that has not been reported for other intestinal cells. Mutated cells showed higher capacities to oxidize 4-hydroxynonanal into 4-hydroxynonanoic acid. The mRNA expression of different enzymes involved in HNE metabolism such as aldehyde dehydrogenase 1A1, 2 and 3A1, glutathione transferase A4-4, or cystine transporter xCT was upregulated in mutated cells compared with wild-type cells. In conclusion, this study suggests that Apc-mutated cells are more efficient than wild-type cells in metabolizing HNE into thiol conjugates and 4-hydroxynonanoic acid due to the higher expression of key biotransformation enzymes. These differential biotransformation capacities would explain the differences of susceptibility between normal and Apc-mutated cells regarding secondary lipid oxidation products.

Topics: Adenomatous Polyposis Coli Protein; Aldehyde Dehydrogenase; Aldehydes; Animals; Biotransformation; Chromatography, High Pressure Liquid; Colon; Colorectal Neoplasms; DNA Damage; Epithelial Cells; Glutathione; Glutathione Transferase; Heme; Humans; Iron; Isotope Labeling; Mass Spectrometry; Mice; Mutation; Oxidation-Reduction; RNA, Messenger; Tumor Cells, Cultured

The effects of polyunsaturated fatty acids (PUFAs) obtained from the diet on colorectal cancer have been widely explored. However, controversial results have been obtained about the role played by the lipid peroxidation products of PUFAs, such as 4-hydroxy-nonenal (HNE), in the control of colon cancer growth. This aldehyde, indeed, showed both procarcinogenic and protective effects. In an attempt to verify the action of HNE, we studied the effects of a low dose of HNE (1 microM), similar to those "physiologically" found in normal cells and plasma, on telomerase activity, a key parameter of malignant transformation. Caco-2 cells were exposed to HNE and, paralleling cell growth inhibition, we observed the down-regulation of telomerase activity and hTERT expression. Similar effects have also been observed in HT-29 cells, in which HNE inhibited cell proliferation, telomerase activity and hTERT expression, suggesting that the inhibition of telomerase activity could be a general mechanism involved in the antiproliferative effect exerted by this aldehyde. Finally, we elucidated the mechanism of hTERT inhibition by HNE. A reduction of GSH content preceded the decrease of telomerase activity, but this only partially explained the telomerase activity inhibition. The major mechanism of HNE action seems to be the modulation of expression and activity of transcription factors belonging to the Myc/Mad/Max network. Since the presence of PUFAs in the diet exposes epithelial colon cells to HNE, this aldehyde could contribute to cell growth control through the inhibitory action on telomerase activity and hTERT expression, suggesting a protective effect on colon mucosa.

Topics: Aldehydes; Apoptosis; Caco-2 Cells; Cell Differentiation; Cell Division; Cell Proliferation; Colorectal Neoplasms; Down-Regulation; Gene Expression; Glutathione; HT29 Cells; Humans; Lipid Peroxidation; Telomerase

Since damage to DNA and other cellular molecules by reactive oxygen species ranks high as a major culprit in the onset and development of colorectal cancer, the aim of the present study is to clarify the role of antioxidant seleonoproteins including glutathione peroxidase (GPx), thioredoxin reductase (TXR) and selenoprotein P (SePP), and the effect of oxidative stress on the progression of colorectal cancer. Expression of 14 oxidative stress-related molecules in both tumorous and non-tumorous tissues in 41 patients was examined by immunohistochemistry and Western blot analysis. Expression levels of proteins modified by 4-hydroxy-2-nonenal (4-HNE), malonyldialdehyde (MDA) and 4-hydroxy-2-hexenal (4-HHE), and the positive rate of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in tumorous tissues were much higher than those in non-tumorous tissues. Glutathione (GSH) content in tumor tissues was much lower than that in non-tumorous tissues. Expression level of selenoproteins such as GPx-1, GPx-3, and SePP, which are rapidly degraded during selenium deprivation, was significantly decreased in tumorous tissues, whereas that of GPx-2, which is resistant to selenium deprivation, was increased. Expression of SePP was decreased at stage III and IV, compared to that of stage II. These data suggest that contrasting expression pattern of the antioxidant selenoproteins plays an important role in the progression of colorectal cancer.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Aldehydes; Antioxidants; Apoptosis; Blotting, Western; Cell Proliferation; Colorectal Neoplasms; Deoxyguanosine; Disease Progression; Female; Glutathione; Glutathione Peroxidase; Humans; Immunohistochemistry; Male; Malondialdehyde; Oxidative Stress; Proliferating Cell Nuclear Antigen; Selenoprotein P; Selenoproteins; Superoxide Dismutase; Superoxide Dismutase-1; Thioredoxin-Disulfide Reductase; Tumor Suppressor Protein p53

The oxidation of polyunsaturated fatty acids during oxidative stress gives rise to a series of toxic alpha,beta-unsaturated aldehydes, including the electrophile 4-hydroxy-2-nonenal (4-HNE) and the related aldehydes, 4-hydroperoxy-2-nonenal (4-HPNE) and 4-oxo-2-nonenal (4-ONE). We synthesized these compounds, as well as the resolved enantiomers of 4-HNE, and compared their toxicities and apoptotic responses in the human colorectal cancer cell line RKO. All of these molecules execute similar death responses at comparable doses over almost identical time frames in RKO cells. The apoptotic response induced by 4-HPNE, 4-ONE, and 4-HNE enantiomers involves activation of caspases, proteolysis of downstream caspase targets, and nucleosomal DNA fragmentation. The results presented herein suggest that these molecules commonly activate certain signaling pathways that control cell death irrespective of their reactive properties.

Topics: Aldehydes; Apoptosis; Carcinoma; Colorectal Neoplasms; DNA Damage; Humans; Lipid Peroxidation; Proteins; Tumor Cells, Cultured

We investigated the mechanism by which 4-hydroxynonenal (HNE), a major aldehydic product of lipid peroxidation, induces apoptosis in tumor cells. Treatment of human colorectal carcinoma (RKO) cells with HNE-induced poly-ADP-ribose-polymerase (PARP) cleavage and DNA fragmentation in a dose- and time-dependent manner. The induction of PARP cleavage and DNA fragmentation paralleled caspase-2, -3, -8, and -9 activation. Pretreatment of cells with an inhibitor of caspase-3, z-DEVD-fmk, or a broad spectrum caspase inhibitor, z-VAD-fmk, abolished caspase activation and subsequent PARP cleavage. Constitutive expression of high levels of Bcl-2 protected cells from HNE-mediated apoptosis. In addition, Bcl-2 overexpression inhibited cytochrome c release from mitochondria and subsequent caspase-2, -3, and -9 activation. These findings demonstrate that HNE triggers apoptotic cell death through a mitochondrion-dependent pathway involving cytochrome c release and caspase activation. Bcl-2 overexpression protected cells from HNE-induced apoptosis through inhibition of cytochrome c release.

Topics: Aldehydes; Apoptosis; Caspase 3; Caspases; Colorectal Neoplasms; Cross-Linking Reagents; Cytochrome c Group; DNA Damage; Enzyme Induction; Gene Expression Regulation, Neoplastic; Genes, bcl-2; Humans; Lipid Peroxidation; Mitochondria; Proto-Oncogene Proteins c-bcl-2; Tumor Cells, Cultured

Few studies have been conducted focusing on a potential role of reactive oxygen species in tumor cell metabolism. Here we studied human colorectal adenocarcinomas and adenomas to determine whether oxidative stress is imposed on cancer cells in vivo and used specific antibodies against 8-hydroxy-2'-deoxyguanosine (8-OHdG), 4-hydroxy-2-nonenal (HNE)-modified proteins, and 3-nitro-L-tyrosine (3-NT) to determine whether there is an association between oxidative stress and cellular proliferation. Higher levels of oxidative modifications in DNA and proteins were observed in carcinoma cells, but not in adenoma cells, than in the corresponding nontumorous epithelial cells by immunohistochemistry as well as high-performance liquid chromatography (HPLC)-based 8-OHdG determination. The fraction of proliferating cell nuclear antigen-positive cells was proportionally associated in adenocarcinomas with the staining intensities of 8-OHdG and 3-NT. Furthermore, Western blot analysis of the proteins extracted from carcinoma cells revealed several specific proteins modified by HNE or peroxynitrite. Thus we concluded that colorectal carcinoma, but not adenoma cells, are exposed to more oxidative stress than their corresponding nontumorous epithelial cells, regardless of clinical stage and histology, and further that the oxidative stress in carcinoma cells might stimulate cellular proliferation.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenocarcinoma; Adenoma; Adult; Aged; Aldehydes; Case-Control Studies; Chromatography, High Pressure Liquid; Colorectal Neoplasms; Deoxyguanosine; Epithelial Cells; Female; Humans; Immunohistochemistry; Male; Middle Aged; Nitrates; Oxidants; Oxidative Stress; Reactive Oxygen Species; Time Factors