Attenuation of catalase activity in the malignant phenotype plays a functional role in an in vitro model for tumor progression

Inhibitory effect of selected Indian honey on colon cancer cell growth by inducing apoptosis and targeting the β-catenin/Wnt pathway

Colon cancer is the most prevalent cause of death from cancer across the globe. Although chemotherapy drugs are predominantly used, their toxicity always remains a cause of concern. As an alternative to synthetic drugs, natural compounds or nutraceuticals are comparatively less toxic. Honey is widely used across different cultures as an alternative form of medicine. It represents a prominent source of plant-phenolic compounds and there is demonstrable evidence of its anti-oxidant and anti-microbial activities. The aim of the present work was to investigate the anti-proliferative effect of some Indian honeys and analyze their mechanism of action in colon cancer. In order to establish the composition-activity relationship, we evaluated the bioactive components present in selected honey samples by GC-MS and HPLC analysis. Indian honey samples showed a significant inhibitory impact on cell growth by restricting cell proliferation, causing apoptosis, and restricting the cell cycle in the G₂/M phase specifically for colon cancer cells. The apoptotic activities, as imparted by the honey samples, were established by Annexin V/PI staining, real-time PCR, and immunoblot analyses. The treated cells showed increased expressions of p53 and caspases 3, 8, and 9, thus indicating the involvement of both extrinsic and intrinsic apoptotic pathways. The honey samples were also found to inhibit the β-catenin/Wnt pathway. In the next phase of the study, the efficacy of these honey samples was evaluated in colon carcinoma induced SD-rats. Overall, these findings demonstrated that selected Indian honeys could be established as effective nutraceuticals for the prevention as well as cure of colon cancer.

Mechanisms exploration of Xiaojin Pills on lung cancer based on metabolomics and network pharmacology

OBJECTIVES

This study was designed to evaluate the pharmacological activity and therapeutic mechanism of Xiaojin Pills (XJW) on lung cancer.

METHODS

Mice were orally administered with Xiaojin Pills for 21 days. Tumour samples were collected to evaluate the antilung cancer effect, and blood samples were collected to identify differential metabolites with metabolomics. Through the analysis of network pharmacology, the active ingredients and targets related to XJW therapy for lung cancer were filtered.

KEY FINDINGS

Different expression of seven metabolites related to seven pathways, including Arachidonic acid metabolism, Citrate cycle, tryptophan metabolism, glyoxylate and dicarboxylate metabolism, arginine and proline metabolism, primary bile acid biosynthesis and nicotinate and nicotinamide metabolism, were demonstrated to explain the efficacy of XJW in the treatment of lung cancer. Furthermore, a total of 19 active ingredients (ursolic acid, α-thujone, pelargonidin, succinic acid, boswellic acid, muscone, daidzein, xanthorrhizol, isoeugenol, oleic acid, β-caryophyllene, vanillin, β-sitosterol, lupeol, palmitic acid, eugenol, methylbutenol, β-elemene and quercetin) acted directly on 9 targets (CAT, PTGS2, PTGS1, CTH, ABTA, ALT1, ME2, AGXT and AGXT 2) and regulated 3 out of 7 metabolites (3-Hydroxyanthranilic acid, Pyruvate and Prostaglandin G2).

CONCLUSIONS

Through metabolomics and network pharmacology analyses, this study demonstrated that the major metabolites of XJW in treating lung cancer were regulated by multitarget and multicomponent interaction network.

A quantitative method for the detection and validation of catalase activity at physiological concentration in human serum, plasma and erythrocytes

A novel method has been proposed to develop a simple, rapid, sensitive and affordable chromogenic attempt for the quantification of catalase (CAT) activity in blood samples. The method is based on the oxidation of pyrocatechol (PC) to give quinone form which by oxidative coupling with aminyl radical of 4-aminoantipyrine (4-AAP) resulting from H₂O₂/CAT to produce a pink colored quinone-imine product with λ_max = 530 nm in a 100 mmol/L of tris buffer of pH 9.8 at room temperature (30 °C). The linearity of CAT assay was between 0.316 and 10 U/mL. The accuracy ranges for CAT having concentrations of 1.25, 5 and 7.5 μmol/L were 89-105.52, 90-107%, and 91-104.58% respectively. Within-run and between-run precision studies showed CV's of 1.98-3.02% (n = 7) and 2.97-4.40% (n = 7), respectively. The detection and quantification limits of CAT were 0.12 and 0.225 μmol/L, respectively. The Michaelis-Menten constant and maximum velocity of the reaction was K_m = 1.052 mM and V_max = 0.168 μmol/min, respectively. The present method provides a convenient means for investigating the usefulness of CAT measurements in biological sample assessing the potential for free radical-induced pathology.

Catalase immunoexpression in colorectal lesions

Introduction

It is generally accepted that the gastrointestinal tract, and especially the colon, is constantly exposed to reactive oxygen species (ROS) that may be responsible for the appearance of genetic mutations. To keep a steady-state control over ROS production-detoxification, organisms have evolved a defensive system. Nevertheless, many reports have described decreased level of antioxidant enzymes, especially catalase (CAT), in cancer tissues.

Aim

In this work we try to assess the immunohistochemical expression of CAT protein in colorectal adenoma and adenocarcinoma samples.

Material and methods

This study was performed on resected specimens obtained from 122 patients who had undergone surgical resection for colorectal cancer, and from 120 patients who had undergone colonoscopy. Paraffin- embedded, 4 µm-thick tissue sections were stained for rabbit polyclonal anti CAT antibody obtained from GeneTex (cat. no. GTX110704).

Results

In adenoma strong immunoexpression was detected mainly in infiltrating mononuclear cells within lamina propria. High expression of CAT was significantly associated with grade of dysplasia (high grade vs. low grade, p = 0.037). In adenocarcinoma samples, the high level of CAT immunoexpression was significantly correlated with histological grade of tumour (G1 vs. G2 vs. G3, p = 0.001) and depth of invasion (T1 vs. T2 vs. T3 vs. T4, p = 0.003).

Conclusions

Development of colorectal cancer is associated with increased expression of CAT in the stage of adenoma and decreased expression in the stage of adenocarcinoma.

Reactive oxygen species-induced activation of Yes-associated protein-1 through the c-Myc pathway is a therapeutic target in hepatocellular carcinoma

BACKGROUND

The Hippo signaling pathway regulates organ size by regulating cell proliferation and apoptosis with terminal effectors including Yes-associated protein-1 (YAP-1). Dysregulation in Hippo pathway has been proposed as one of the therapeutic targets in hepatocarcinogenesis. The levels of reactive oxygen species (ROS) increase during the progression from early to advanced hepatocellular carcinoma (HCC).

AIM

To study the activation of YAP-1 by ROS-induced damage in HCC and the involved signaling pathway.

METHODS

The expression of YAP-1 in HCC cells (Huh-7, HepG2, and SNU-761) was quantified using real-time polymerase chain reaction and immunoblotting. Human HCC cells were treated with H₂O₂, which is a major component of ROS in living organisms, and with either YAP-1 small interfering RNA (siRNA) or control siRNA. To investigate the role of YAP-1 in HCC cells under oxidative stress, MTS assays were performed. Immunoblotting was performed to evaluate the signaling pathway responsible for the activation of YAP-1. Eighty-eight surgically resected frozen HCC tissue samples and 88 nontumor liver tissue samples were used for gene expression analyses.

RESULTS

H₂O₂ treatment increased the mRNA and protein expression of YAP-1 in HCC cells (Huh-7, HepG2, and SNU-761). Suppression of YAP-1 using siRNA transfection resulted in a significant decrease in tumor proliferation during H₂O₂ treatment both in vitro and in vivo (both P < 0.05). The oncogenic action of YAP-1 occurred via the activation of the c-Myc pathway, leading to the upregulation of components of the unfolded protein response (UPR), including 78-kDa glucose-regulated protein and activating transcription factor-6 (ATF-6). The YAP-1 mRNA levels in human HCC tissues were upregulated by 2.6-fold compared with those in nontumor tissues (P < 0.05) and were positively correlated with the ATF-6 Levels (Pearson’s coefficient = 0.299; P < 0.05).

CONCLUSION

This study shows a novel connection between YAP-1 and the UPR through the c-Myc pathway during oxidative stress in HCC. The ROS-induced activation of YAP-1 via the c-Myc pathway, which leads to the activation of the UPR pathway, might be a therapeutic target in HCC.

Reprogramming human A375 amelanotic melanoma cells by catalase overexpression: Reversion or promotion of malignancy by inducing melanogenesis or metastasis

Advanced melanoma is the most aggressive form of skin cancer. It is highly metastatic and dysfunctional in melanogenesis; two processes that are induced by H₂O₂. This work presents a melanoma cell model with low levels of H₂O₂ induced by catalase overexpression to study differentiation/dedifferentiation processes. Three clones (A7, C10 and G10) of human A375 amelanotic melanoma cells with quite distinct phenotypes were obtained. These clones faced H₂O₂ scavenging by two main strategies. One developed by clone G10 where ROS increased. This resulted in G10 migration and metastasis associated with the increased of cofilin-1 and CAP1. The other strategy was observed in clone A7 and C10, where ROS levels were maintained reversing malignant features. Particularly, C10 was not tumorigenic, while A7 reversed the amelanotic phenotype by increasing melanin content and melanocytic differentiation markers. These clones allowed the study of potential differentiation and migration markers and its association with ROS levels in vitro and in vivo, providing a new melanoma model with different degree of malignancy.

Downregulation of catalase by CuO nanoparticles via hypermethylation of CpG island II on the catalase promoter

The advent of nanotechnology has led to new applications of copper as antibiotic treatment alternatives, nanocomposite coatings, catalysts, and lubricants among others. However, few studies address the impact of nano-size copper on the molecular mechanism of eukaryotic cells. Therefore, in the present study, the human hepatic cell line (WRL-68) was used to evaluate the molecular mechanism involved in the adverse effect of CuO NPs. CuO NPs were characterized by scanning electron microscopy and dynamic light scattering to confirm their 100 nm size and their purity was determined by Fourier transform infra-red spectroscopy. The side scattered intensity in WRL-68 cells at a CuO NP concentration of 250, 500, 750 and 1000 μM was found to be 108.83%, 126.86%, 189.03% and 250.88% respectively. The reactive oxygen species (ROS) generation at a CuO NP concentration of 1000 μM in WRL-68 cells was 417.75%. Moreover, the ROS induced methylation of CpG island II on the catalase promoter and downregulated catalase expression at the transcriptional level in WRL-68 cells. Furthermore, the activity of the catalase enzyme was found to decrease with an increase in concentration of CuO NPs. Subsequently, the proliferation of the WRL-68 cells was increased on exposure to the CuO NPs as demonstrated by the mitochondrial activity in the MTT assay. Conclusively, it is demonstrated that exposure of CuO NPs at 1000 μM for 24 h in the WRL-68 cell induced methylation of CpG island II via ROS on the catalase promoter and downregulated catalase expression at the transcriptional level. The obtained molecular mechanistic insights described adverse effects related to the CuO NPs.

Free radicals hasten head and neck cancer risk: A study of total oxidant, total antioxidant, DNA damage, and histological grade

Background:

Free radicals such as reactive oxygen species (ROS), which induce oxidative stress, are the main contributors to head and neck carcinogenesis (HNC). The present study was conducted with the aim to assess the oxidant/antioxidant status and DNA damage analysis in head and neck cancer/control patients.

Materials and Methods:

This prospective study was conducted on 60 patients with biopsy-proven HNC and 17 patients of head and neck disease (HND). The total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI) were determined by novel automatic colorimetric methods from tissue homogenate. DNA damage analysis was determined by single cell gel electrophoresis (SCGE).

Results:

The mean age of the study cohort was 46.65 ± 14.84 years for HNC patients, while it was 49.41 ± 13.00 years for HND patients. There were no significant differences found between the two groups with respect to demographic presentation except tobacco addiction. The association between oxidative stress parameters and DNA damage analysis with study group revealed the following. (A) DNA damage - tissue homogenate TOS and OSI were significantly higher in HNC subjects than in HND (16.06 ± 1.78 AU vs 7.86 ± 5.97 AU, P < 0.001; 53.00 ± 40.61 vs 19.67 ± 21.90, P < 0.01; 7.221 ± 5.80 vs 2.40 ± 2.54, P < 0.01, respectively), while TAS was significantly decreased. (B) Aggressive histological features were identified, more commonly with higher TOS and lower TAS [probability (P) = 0.002, relative risk (RR) = 11.838, 95% confidence interval CI = 2.514-55.730 and P = 0.043, RR = 0.271, 95% CI = 0.077-0.960, respectively].

Conclusion:

The increase in free radicals may be the event that led to the reduction of antioxidant status in HNC, thus explaining the oxidative damage of DNA and the severity of disease. Increased OSI represents a general mechanism in its pathogenesis.

trans-Chalcone, a flavonoid precursor, inhibits UV-induced skin inflammation and oxidative stress in mice by targeting NADPH oxidase and cytokine production

trans-Chalcone inhibits UV-induced skin inflammation and also indirectly reduces oxidative stress.

Prophylaxis of Diallyl Disulfide on Skin Carcinogenic Model via p21-dependent Nrf2 stabilization

Cancer prevention through intake of biologically active natural products appears to be an accessible way to reduce the risk of cancer. Diallyl disulfide (DADS), a major garlic derivative, has exhibited potential role in cancer therapy. The study is aimed to evaluate the prophylactic effect of DADS in chemically induced mouse skin carcinogenesis and investigate the molecular targets mediated by DADS. Two-stage chemically induced carcinogenesis model by cutaneous application of DMBA and subsequent TPA was established to study the prophylactic effect of DADS. As a result, we observed that DADS dose-dependently attenuated skin tumor incidence and multiplicity in the model mice, which was related to the up-regulation of a bunch of antioxidant enzymes activities and the nuclear accumulation of Nrf2. Furthermore, we developed skin carcinogenesis in Nrf2 knockout mice which could reverse the activity of DADS. Finally, we uncovered the underlying mechanism that DADS promoted the endogenous interaction between p21 and Nrf2, which was critical for impairing the Keap1-mediated degradation of Nrf2. Based on the results, we concluded that DADS was a promising cancer chemoprevention agent and suggested a garlic-rich diet might be beneficial to reduce the cancer risk in our daily life.

Mitochondria Biogenesis and Bioenergetics Gene Profiles in Isogenic Prostate Cells with Different Malignant Phenotypes

Background. The most significant hallmarks of cancer are directly or indirectly linked to deregulated mitochondria. In this study, we sought to profile mitochondria associated genes in isogenic prostate cell lines with different tumorigenic phenotypes from the same patient. Results. Two isogenic human prostate cell lines RC77N/E (nonmalignant cells) and RC77T/E (malignant cells) were profiled for expression of mitochondrial biogenesis and energy metabolism genes by qRT-PCR using the Human Mitochondria and the Mitochondrial Energy Metabolism RT² PCR arrays. Forty-seven genes were differentially regulated between the two cell lines. The interaction and regulatory networks of these genes were generated by Ingenuity Pathway Analysis. UCP2 was the most significantly upregulated gene in primary adenocarcinoma cells in the current study. The overexpression of UCP2 upon malignant transformation was further validated using human prostatectomy clinical specimens. Conclusions. This study demonstrates the overexpression of multiple genes that are involved in mitochondria biogenesis, bioenergetics, and modulation of apoptosis. These genes may play a role in malignant transformation and disease progression. The upregulation of some of these genes in clinical samples indicates that some of the differentially transcribed genes could be the potential targets for therapeutic interventions.

Prognostic significance of catalase expression and its regulatory effects on hepatitis B virus X protein (HBx) in HBV-related advanced hepatocellular carcinomas

Hepatitis B virus X protein (HBx) plays a role in liver cancer development. We previously showed that ROS increased HBx levels and here, we investigated the role of antioxidants in the regulation of HBx expression and their clinical relevance. We found that overexpression of catalase induced a significant loss in HBx levels. The cysteine null mutant of HBx (Cys-) showed a dramatic reduction in its protein stability. In clonogenic proliferation assays, Huh7-X cells produced a significant number of colonies whereas Huh7-Cys- cells failed to generate them. The Cys at position 69 of HBx was crucial to maintain its protein stability and transactivation function in response to ROS. Among 50 HBV-related hepatocellular carcinoma (HCC) specimens, 72% of HCCs showed lower catalase levels than those of surrounding non-tumor tissues. In advanced stage IV, catalase levels in non-tumor tissues were increased whereas those in tumors were further reduced. Accordingly, patients with a high T/N ratio for catalase showed significantly longer survival than those with a low T/N ratio. Together, catalase expression in HCC patients can be clinically useful for prediction of patient survival, and restoration of catalase expression in HCCs could be an important strategy for intervention in HBV-induced liver diseases.

Manganese superoxide dismutase (SOD2/MnSOD)/catalase and SOD2/GPx1 ratios as biomarkers for tumor progression and metastasis in prostate, colon, and lung cancer

The role of manganese-dependent superoxide dismutase (SOD2/MnSOD) during tumor progression has been studied for several decades with controversial results. While SOD2 downregulation was initially associated with tumor initiation and was proposed as a tumor suppressor gene, recent studies have reported that SOD2 might favor tumor progression and dissemination. To our knowledge this is the first time that changes in SOD2 expression in three different types of tumors, i.e., prostate, lung, and colon cancer, are studied by analyzing both SOD2 mRNA and protein levels in a total of 246 patients' samples. In prostate samples, SOD2 protein levels were also increased, especially in middle stage tumors. In the case of colon and lung tumors both mRNA and protein SOD2 levels were increased in malignant tissues compared to those in nontumor samples. More importantly, all metastases analyzed showed increased levels of SOD2 when compared to those of normal primary tissue and healthy adjacent tissue. Together, these results suggest that a common redox imbalance in these three types of tumor occurs at intermediate stages which then might favor migration and invasion, leading to a more aggressive cancer type. Consequently, the ratios SOD2/catalase and SOD2/Gpx1 could be considered as potential markers during progression from tumor growth to metastasis.

Nutraceutical preconditioning with arginine and oil mixes. Effects on inflammatory mediators, oxidative stress and lipid profile in patients undergoing radical prostatectomy

PURPOSE

To investigate whether there is any effect resulting from preconditioning with nutraceutical supplementation containing arginine and oil mixes with high ω9:ω6 ratio and low ω6:ω3 ratio containing EPA and DHA, ALA fatty acids on inflammatory mediators, antioxidant and lipid profile modulation in surgical trauma.

METHODS

Twenty-six men scheduled for radical prostatectomy were randomized into three groups and treated as follows: Group 1 (skim milk, 0% fat), Group 2 (supplement with ω6:ω3 ratio of 8:1 and arginine) and Group 3 (supplement with high ω9:ω6 ratio of 3.2:1 and low ω6:ω3 ratio of 1.4:1 and arginine). Patients received skin milk or supplements twice a day (200 ml) during five days prior to surgery. Peripheral venous blood samples were collected at three different timepoints: five days before surgery (PRE), before anesthesia induction (IND) and on the 2nd postoperative day (POS). Parameters analyzed included inflammatory cytokines (IL-1β, IL-6, IL-8 and TNF-α), antioxidants (catalase), lipid profile and heat shock protein (HSP-27).

RESULTS

There were no significant differences between groups on inflammatory mediators and antioxidant parameters. However, lipid profile values (Cholesterol, LDL, Triglycerides, VLDL), were significantly different.

CONCLUSION

Preconditioning with arginine and oil mixes containing high ω9:ω6 ratio and low ω6:ω3 ratio, has no effects on inflammatory mediators and oxidative stress in patients undergoing radical prostatectomy. Reduction of cholesterol, triglycerides, LDL and VLDL profiles may be related to the trauma effect.

Selective protection of normal cells during chemotherapy by RY4 peptides

Mitochondrial targeted Szeto-Schiller (SS) peptides have recently gained attention for their antioxidative stress ability; however, the functional variations between normal and cancer cells have not been determined. Here, we report the results of such experiments conducted with a newly designed class of peptide called RY4, which is based on SS peptide sequence characteristics. The RY4 peptide exhibits distinct differences in antioxidative stress response between normal and cancer cells when challenged with chemotherapeutics like the glycolytic inhibitor dichloroacetate (DCA), the platinating agent carboplatin, and the DNA damage inducer doxorubicin. Interestingly, only normal human cells were protected by the RY4 peptide and catalase (CAT) activity was significantly enhanced in normal but not tumor cells when incubated with RY4. Pull-down, coimmunoprecipitation, and LC/MS-MS proteomic analysis demonstrated that RY4 and catalase are capable of forming protein complexes. Finally, in vivo efficacy was evaluated by intraperitoneal administration of RY4 into a lung cancer xenograft model, which revealed significant myocardiocyte protection from doxorubicin-induced cardiotoxicity without diminishing doxorubicin's tumoricidal effects. Taken together, RY4 offers selective protection to normal cells from chemotherapy-induced toxicity by enhancing the activity of cellular antioxidant enzymes.

IMPLICATIONS

RY4 peptides selectively reduce chemotherapeutic-induced oxidative stress and represent a new class of chemoprotective agents with clinical potential.

Loss of p27 upregulates MnSOD in a STAT3-dependent manner, disrupts intracellular redox activity and enhances cell migration

Cell migration is a dynamic process that is central to a variety of physiological functions as well as disease pathogenesis. The modulation of cell migration by p27 (officially known as CDKN1B) has been reported, but the exact mechanism(s) whereby p27 interacts with downstream effectors that control cell migration have not been elucidated. By systematically comparing p27(+/+) mouse embryonic fibroblasts (MEFs) with genetically ablated p27(-/-) MEFs using wound-healing, transwell and time-lapse microscopic analyses, we provide direct evidence that p27 inhibits both directional and random cell migration. Identical results were obtained with normal and cancer epithelial cells using complementary knockdown and overexpression approaches. Additional studies revealed that overexpression of manganese superoxide dismutase (MnSOD, officially known as SOD2) and reduced intracellular oxidation played a key role in increased cell migration in p27-deficient cells. Furthermore, we identified signal transducer and activator of transcription 3 (STAT3) as the transcription factor responsible for p27-regulated MnSOD expression, which was further mediated by ERK- and ATF1-dependent transactivation of the cAMP response element (CRE) within the Stat3 promoter. Collectively, our data strongly indicate that p27 plays a crucial negative role in cell migration by inhibiting MnSOD expression in a STAT3-dependent manner.

Reactive oxygen species production by catechol stabilized copper nanoparticles

Stable Cu nanoparticles (NPs) prepared using catechol containing dopamine-based linkers could generate reactive oxygen species (ROS) that can activate peroxidase enzymes and catalyze the degradation of fluorescent dye pollutants.

Preventative topical diclofenac treatment differentially decreases tumor burden in male and female Skh-1 mice in a model of UVB-induced cutaneous squamous cell carcinoma

Ultraviolet B (UVB) light is the major environmental carcinogen contributing to non-melanoma skin cancer (NMSC) development. There are over 3.5 million NMSC diagnoses in two million patients annually, with men having a 3-fold greater incidence of squamous cell carcinoma (SCC) compared with women. Chronic inflammation has been linked to tumorigenesis, with a key role for the cyclooxygenase-2 (COX-2) enzyme. Diclofenac, a COX-2 inhibitor and non-steroidal anti-inflammatory drug, currently is prescribed to patients as a short-term therapeutic agent to induce SCC precursor lesion regression. However, its efficacy as a preventative agent in patients without evidence of precursor lesions but with significant UVB-induced cutaneous damage has not been explored. We previously demonstrated in a murine model of UVB-induced skin carcinogenesis that when exposed to equivalent UVB doses, male mice had lower levels of inflammation but developed increased tumor multiplicity, burden and grade compared with female mice. Because of the discrepancy in the degree of inflammation between male and female skin, we sought to determine if topical treatment of previously damaged skin with an anti-inflammatory COX-2 inhibitor would decrease tumor burden and if it would be equally effective in the sexes. Our results demonstrated that despite observed sex differences in the inflammatory response, prolonged topical diclofenac treatment of chronically UVB-damaged skin effectively reduced tumor multiplicity in both sexes. Unexpectedly, tumor burden was significantly decreased only in male mice. Our data suggest a new therapeutic use for currently available topical diclofenac as a preventative intervention for patients predisposed to cutaneous SCC development before lesions appear.

Redox modulation of the DNA damage response

Lesions to DNA trigger the DNA-damage response (DDR), a complex, multi-branched cell-intrinsic process targeted to DNA repair, or elimination of the damaged cells by apoptosis. DDR aims at reducing permanence of mutated cells, decreasing the risk of tumor development: the more stringent the response, the lower the likelihood that sub-lethally damaged, unrepaired cells survive and proliferate. Accordingly, leakage often occurs in tumor cells with compromised DDR, accumulating mutations and accelerating tumor progression. Oxidations mediate DNA damage upon different insults such as UV, X and γ radiation, pollutants, poisons, or endogenous disequilibria, producing different types of lesions that trigger DDR, which can be alleviated by antioxidants. But reactive oxygen species (ROS), and the enzymes involved in their production or scavenging, also participate in DDR signaling, modulating the activity of key enzymes, and regulating the stringency of DDR. Accordingly, antioxidant enzymes such as superoxide dismutase play intimate and complex roles in tumor development, exceeding the basal roles of preventing the initial DNA damage. Likewise, it is emerging that dietary antioxidants help controlling tumor onset and progression by preventing DNA damage and by acting on cell cycle checkpoints, opening a novel and promising frontier to anticancer therapy.

Association of Pb, Cd, and Se concentrations and oxidative damage-related markers in different grades of prostate carcinoma

Prostate cancer is known to be affected by the heavy metal levels and oxidative damage of the body, yet there are very few studies which look into the way it occurs. The aim of this study was to determine whether blood and tissue lead (Pb), cadmium (Cd), and selenium (Se) levels are associated with oxidative damage in the context of prostate cancer progression and development. Seventy-nine patients comprising 25 patients with benign prostatic hypertrophy (BPH), 23 patients with malignant prostatic carcinoma (malign Ca), 16 patients with low-grade prostatic intraepithelial neoplasia (LGPIN), and 15 patients with high-grade prostatic intraepithelial neoplasia (HGPIN) diagnosed on the basis of their clinical profile, transrectal ultrasonography, and histopathology were included in this study. Cd and Pb levels in whole blood were found to be increased in patients with HGPIN compared with the BPH group; also, the levels of Cd in whole blood and tissue were found to be increasing in patients with malign Ca, unlike BPH patients. Moreover, the levels of malondialdehyde (MDA) in plasma and tissue were significantly increased in malign Ca, LGPIN, and HGPIN than those in BPH. However, the levels of tissue Pb were found to be decreasing in BPH, unlike the malign Ca and HGPIN patients, and the levels of tissue protein carbonyls in malign Ca were significantly lower than those in HGPIN. The levels of tissue reduced glutathione (GSH) in malign Ca were significantly lower than those in BPH. Additionally, the levels of Se in serum and tissue in LGPIN were significantly lower than those in BPH. The serum Se levels in HGPIN were also significantly lower than those in BPH and malign Ca groups. Furthermore, the concentrations of serum Se in LGPIN were significantly lower than those in malign Ca. From the Pearson correlation analysis, there were significant positive correlations between tissue Cd and MDA levels in malign Ca, LGPIN, and HGPIN and between the tissue Pb and tissue MDA and protein carbonyl levels in malign Ca. Blood Pb and tissue Pb were also significantly positively correlated with plasma MDA and protein carbonyl levels in malign Ca. In addition, blood Pb was significantly positively correlated with tissue MDA and protein carbonyl levels in malign Ca, and a significant positive correlation was also found between blood Cd and plasma protein carbonyls and tissue MDA in LGPIN. We observed that altered prooxidant-antioxidant balance and heavy metal levels may lead to an increase in oxidative damage and may consequently play an important role in prostate carcinogenesis. These findings indicate that changes in the levels of Pb, Cd, Se, MDA, protein carbonyls, and GSH in the blood and/or tissue are related to the prostatic carcinoma development and progression, although triggering one of the mentioned changes is unknown; therefore, further study is required to determine the exact steps of the process and clarify the roles of different substances in order to obtain a more detailed explanation of the phenomenon.

UV light B-mediated inhibition of skin catalase activity promotes Gr-1+ CD11b+ myeloid cell expansion

Skin cancer incidence and mortality are higher in men compared to women, but the causes of this sex discrepancy remain largely unknown. Ultraviolet light exposure induces cutaneous inflammation and neutralizes cutaneous antioxidants. Gr-1⁺CD11b⁺ myeloid cells are heterogeneous bone marrow-derived cells that promote inflammation-associated carcinogenesis. Reduced activity of catalase, an antioxidant present within skin, has been associated with skin carcinogenesis. We utilized the outbred, immune competent Skh-1 hairless mouse model of ultraviolet light B (UVB)-induced inflammation and non-melanoma skin cancer to further define sex discrepancies in UVB-induced inflammation. Our results demonstrated that male skin had relatively lower baseline catalase activity, which was inhibited following acute UVB exposure in both sexes. Further analysis revealed that skin catalase activity inversely correlated with splenic Gr-1⁺CD11b⁺ myeloid cell percentage. Acute UVB exposure induced Gr-1⁺CD11b⁺ myeloid cell skin infiltration, which was inhibited to a greater extent in males by topical catalase treatment. In chronic UVB studies, we demonstrated that the percentage of splenic Gr-1⁺CD11b⁺ myeloid cells was 55% higher in male tumor-bearing mice compared to their female counterparts. Together, our findings indicate that lower skin catalase activity in male mice may at least in part contribute to increased UVB-induced Gr-1⁺CD11b⁺ myeloid cells and subsequent skin carcinogenesis.

Reactive oxygen species downregulate catalase expression via methylation of a CpG island in the Oct-1 promoter

Reactive oxygen species (ROS) caused oxidative stress plays a key role in carcinogenesis. The POU domain transcription factor Oct-1 and catalase is closely associated with ROS. However, a correlation between these two key proteins has not been demonstrated before. In this report, we show that Oct-1 acts as an activator of catalase, by binding to the catalase promoter in hepatocellular carcinoma (HCC) cell lines. In addition, we suggest that Oct-1 is downregulated by ROS via CpG island methylation in its promoter. These findings contribute to a better understanding of the epigenetic changes induced by ROS in the process of carcinogenesis.

The Na+/H+ exchanger controls deoxycholic acid-induced apoptosis by a H+-activated, Na+-dependent ionic shift in esophageal cells

Apoptosis resistance is a hallmark of cancer cells. Typically, bile acids induce apoptosis. However during gastrointestinal (GI) tumorigenesis the cancer cells develop resistance to bile acid-induced cell death. To understand how bile acids induce apoptosis resistance we first need to identify the molecular pathways that initiate apoptosis in response to bile acid exposure. In this study we examined the mechanism of deoxycholic acid (DCA)-induced apoptosis, specifically the role of Na⁺/H⁺ exchanger (NHE) and Na⁺ influx in esophageal cells. In vitro studies revealed that the exposure of esophageal cells (JH-EsoAd1, CP-A) to DCA (0.2 mM -0.5 mM) caused lysosomal membrane perturbation and transient cytoplasmic acidification. Fluorescence microscopy in conjunction with atomic absorption spectrophotometry demonstrated that this effect on lysosomes correlated with influx of Na⁺, subsequent loss of intracellular K⁺, an increase of Ca²⁺ and apoptosis. However, ethylisopropyl-amiloride (EIPA), a selective inhibitor of NHE, prevented Na⁺, K⁺ and Ca²⁺ changes and caspase 3/7 activation induced by DCA. Ouabain and amphotericin B, two drugs that increase intracellular Na⁺ levels, induced similar changes as DCA (ion imbalance, caspase3/7 activation). On the contrary, DCA-induced cell death was inhibited by medium with low a Na⁺ concentrations. In the same experiments, we exposed rat ileum ex-vivo to DCA with or without EIPA. Severe tissue damage and caspase-3 activation was observed after DCA treatment, but EIPA almost fully prevented this response. In summary, NHE-mediated Na⁺ influx is a critical step leading to DCA-induced apoptosis. Cells tolerate acidification but evade DCA-induced apoptosis if NHE is inhibited. Our data suggests that suppression of NHE by endogenous or exogenous inhibitors may lead to apoptosis resistance during GI tumorigenesis.

Effects of synbiotic fermentation products on primary chemoprevention in human colon cells

The consumption of synbiotics, a mixture of probiotics and indigestible food constituents such as dietary fiber, has been reported to reduce colon cancer risk. We investigated the effects of fermented wheat aleurone enriched with the probiotics Lactobacillus rhamnosus GG/Bifidobacterium animalis supsp. lactis on the gene expression and functional end points related to cellular defence in HT29 and primary human colon cells. Aleurone was digested and fermented in vitro with/without probiotics. The resulting fermentation supernatants (fs) were analyzed for concentrations of deoxycholic acid and ammonia. The cells were treated with the fs, and effects on gene expression of catalase, GSTP1 and SULT2B1, enzyme activity of catalase and glutathione S-transferase as well as H₂O₂-induced DNA damage were examined. Fermentation of aleurone reduced deoxycholic acid concentration by 84%, while the probiotics enhanced this effect. Ammonia was increased by fs aleurone, whereas a reduction occurred by the addition of L. rhamnosus GG/B. animalis supsp. lactis 12. GSTP1 expression tended to result in an increase by the fs aleurone in both cell types, whereas the probiotics could not additionally increase the effect. Catalase was not modulated by fs aleurone enriched with probiotics. Only in HT29 cells, expression of SULT2B1 was enhanced by fs aleurone. Enzyme activity of catalase and glutathione S-transferase was induced (2-3.6 fold, 72 h) in HT29 cells only. Addition of probiotics had no influence on this effect. In HT29 cells, a reduced H₂O₂-induced DNA damage by the fs aleurone after 48 h, enhanced by the addition of probiotics, was detected. The observed effects could improve detoxification of xenobiotics and therefore may lower colon cancer risk.

Mitochondrial targeted catalase suppresses invasive breast cancer in mice

BACKGROUND

Treatment of invasive breast cancer has an alarmingly high rate of failure because effective targets have not been identified. One potential target is mitochondrial generated reactive oxygen species (ROS) because ROS production has been associated with changes in substrate metabolism and lower concentration of anti-oxidant enzymes in tumor and stromal cells and increased metastatic potential.

METHODS

Transgenic mice expressing a human catalase gene (mCAT) were crossed with MMTV-PyMT transgenic mice that develop metastatic breast cancer. All mice (33 mCAT positive and 23 mCAT negative) were terminated at 110 days of age, when tumors were well advanced. Tumors were histologically assessed for invasiveness, proliferation and metastatic foci in the lungs. ROS levels and activation status of p38 MAPK were determined.

RESULTS

PyMT mice expressing mCAT had a 12.5 per cent incidence of high histological grade primary tumor invasiveness compared to a 62.5 per cent incidence in PyMT mice without mCAT. The histological grade correlated with incidence of metastasis with 56 per cent of PyMT mice positive for mCAT showing evidence of pulmonary metastasis compared to 85.4 per cent of PyMT mice negative for mCAT with pulmonary metastasis (p ≤ 0.05). PyMT tumor cells expressing mCAT had lower ROS levels and were more resistant to hydrogen peroxide-induced oxidative stress than wild type tumor cells, suggesting that mCAT has the potential of quenching intracellular ROS and subsequent invasive behavior. The metastatic tumor burden in PyMT mice expressing mCAT was 0.1 mm2/cm2 of lung tissue compared with 1.3 mm2/cm2 of lung tissue in PyMT mice expressing the wild type allele (p ≤ 0.01), indicating that mCAT could play a role in mitigating metastatic tumor progression at a distant organ site. Expression of mCAT in the lungs increased resistance to hydrogen peroxide-induced oxidative stress that was associated with decreased activation of p38MAPK suggesting ROS signaling is dependent on p38MAPK for at least some of its downstream effects.

CONCLUSION

Targeting catalase within mitochondria of tumor cells and tumor stromal cells suppresses ROS-driven tumor progression and metastasis. Therefore, increasing the antioxidant capacity of the mitochondrial compartment could be a rational therapeutic approach for invasive breast cancer.

Mitochondrial subversion in cancer

Mitochondria control essential cellular activities including generation of ATP via oxidative phosphorylation. Mitochondrial DNA (mtDNA) mutations in the regulatory D-loop region and somatic mtDNA mutations are common in primary human cancers. The biological impact of a given mutation may vary, depending on the nature of the mutation and the proportion of mutant mtDNAs carried by the cell. Identification of mtDNA mutations in precancerous lesions supports their early contribution to cell transformation and cancer progression. Introduction of mtDNA mutations in transformed cells has been associated with increased ROS production and tumor growth. Studies reveal that increased and altered mtDNA plays a role in the development of cancer but further work is required to establish the functional significance of specific mitochondrial mutations in cancer and disease progression. This review offers some insight into the extent of mtDNA mutations, their functional consequences in tumorigenesis, mitochondrial therapeutics, and future clinical application.

Peroxisome proliferator-activated receptor γ regulates angiotensin II-induced catalase downregulation in adventitial fibroblasts of rats

Peroxisome proliferator-activated receptor (PPAR) γ ligands oppose the effect induced by angiotensin II (Ang II) to reduce oxidative stress and improve antioxidant status. In this study, Ang II inhibited catalase (CAT) and peroxisome proliferator-activated receptor γ (PPAR γ) protein and mRNA expressions. Transfection with PPAR γ small-interfering RNA (siRNA) led to a reduction in CAT expression. PPAR γ ligands enhanced CAT expression and inhibited extracellular signal-regulated kinase 1/2 activation. We further reveal that Ang II type 1 receptor is not involved in the inhibitory effects of PPAR γ ligands on Ang II stimulatory events.

Fermented wheat aleurone induces enzymes involved in detoxification of carcinogens and in antioxidative defence in human colon cells

Dietary fibre is fermented by the human gut flora resulting mainly in the formation of SCFA, for example, acetate, propionate and butyrate. SCFA, in particular butyrate, may be important for secondary cancer prevention by inducing apoptosis and inhibiting cell growth of cancer cells, thereby inhibiting the promotion and/or progression of cancer. Furthermore, SCFA could also act on primary cancer prevention by activation of detoxifying and antioxidative enzymes. We investigated the effects of fermented wheat aleurone on the expression of genes involved in stress response and toxicity, activity of drug-metabolising enzymes and anti-genotoxic potential. Aleurone was digested and fermented in vitro to obtain samples that reflect the content of the colon. HT29 cells and colon epithelial stripes were incubated with the resulting fermentation supernatant fractions (fs) and effects on mRNA expression of CAT, GSTP1 and SULT2B1 and enzyme activity of glutathione S-transferase (GST) and catalase (CAT) were measured. Fermented aleurone was also used to study the protection against H2O2-induced DNA damage in HT29 cells. The fs of aleurone significantly induced the mRNA expression of CAT, GSTP1 and SULT2B1 (HT29) and GSTP1 (epithelial stripes), respectively. The enzyme activities of GST (HT29) and CAT (HT29, epithelial stripes) were also unambiguously increased (1·4- to 3·7-fold) by the fs of aleurone. DNA damage induced by H2O2 was significantly reduced by the fs of aleurone after 48 h, whereupon no difference was observed compared with the faeces control. In conclusion, fermented aleurone is able to act on primary prevention by inducing mRNA expression and the activity of enzymes involved in detoxification of carcinogens and antioxidative defence.

Antineoplastic activities of MT81 and its structural analogue in Ehrlich ascites carcinoma-bearing Swiss Albino mice

Many fungal toxins exhibit in vitro and in vivo antineoplastic effects on various cancer cell types. Luteoskyrin,a hydroxyanthraquinone has been proved to be a potent inhibitor against Ehrlich ascites tumor cells. The comparative antitumor activity and antioxidant status of MT81 and its structural analogue [Acetic acid-MT81 (Aa-MT81)] having polyhydroxyanthraquinone structure were assessed against Ehrlich ascites carcinoma (EAC) tumor in mice. The in vitro cytotoxicity was measured by the viability of EAC cells after direct treatment of the said compounds. In in vivo study, MT81 and its structural analogue were administered (i.p.) at the two different doses (5, 7 mg MT81; 8.93, 11.48 mg Aa-MT81/kg body weight) for 7 days after 24 hrs. of tumor inoculation. The activities were assessed using mean survival time (MST), increased life span (ILS), tumor volume, viable tumor cell count, peritoneal cell count, protein percentage and hematological parameters. Antioxidant status was determined by malondialdehyde (MDA) and reduced glutathione (GSH) content, and by the activity of superoxide dismutase (SOD) and catalase (CAT). MT81 and its structural analogues increased the mean survival time, normal peritoneal cell count. They decreased the tumor volume, viable tumor cell count, hemoglobin percentage and packed cell volume. Differential counts of WBC, total counts of RBC & WBC that altered by EAC inoculation, were restored in a dose-dependent manner. Increased MDA and decreased GSH content and reduced activity of SOD, and catalase in EAC bearing mice were returned towards normal after the treatment of MT81 and its structural analogue. Being less toxic than parent toxin MT81, the structural analogue showed more prominent antineoplastic activities against EAC cells compared to MT81. At the same time, both compounds exhibit to some extent antioxidant potential for the EAC-bearing mice.

Photodynamic therapy with 5-aminolevulinic acid and diamino acid derivatives of protoporphyrin IX reduces papillomas in mice without eliminating transformation into squamous cell carcinoma of the skin

Photodynamic therapy (PDT) is used to treat malignant and nonmalignant diseases. It is also used for cosmetological skin treatment. PDT is generally considered to have a low risk of carcinogenicity. However, instances of nonmalignant human tumors turning malignant have been linked to PDT. In this study, we used 5-aminolevulinic (ALA) acid and 3 water soluble photosensitizers-PP(Arg)(2), PP(Ser)(2)Arg(2), PP(Ala)(2)Arg(2), all diamino acid derivatives of protoporphyrin IX-to treat benign papillomas in FVB/N mice induced by 7,12-dimethylbenz(a)anthracene (DMBA)-12-O-tetradecanoyl-phorbol-13-acetate (TPA). Of these drugs, ALA and PP(Arg)(2) were found the most efficient. PDT reduced the number of papillomas, but with increasing effectiveness of the drugs, the risk of malignant transformation of the papillomas into squamous cell carcinomas increased. The underlying mechanisms are not clear and further investigations are needed.

Progestins induce catalase activities in breast cancer cells through PRB isoform: correlation with cell growth inhibition

Reactive oxygen species (ROS) have been suggested to participate in tumor emergence due to their mitogenic and apoptotic signaling, and as contributors to DNA structural damage. Here we report that progesterone and various synthetic steroids with progestin potencies (norethisterone acetate, MPA, and Tibolone) counteract cell growth induced by hydrogen peroxide (H(2)O(2)), through a potent induction of catalase activities, in breast cancer cells and normal human epithelial breast cells. At physiological concentrations, progesterone and the pure progestin, Org2058, displayed the most potent H(2)O(2) detoxification ability suggesting its effect was characteristic of its progestin potency. We also report on the enhancement of catalase activities by progesterone receptor isoform B (PRB), as determined from experiments using antiprogestins and MDA-MB-231, cells engineered for the selective expression of progesterone receptor isoform A or B. The potent action of progesterone on catalase activities indicates its contribution to a beneficial role in breast cell homeostasis.

Loss of catalase increases malignant mouse keratinocyte cell growth through activation of the stress activated JNK pathway

A cell line that produces mouse squamous cell carcinoma (6M90) was modified to develop a cell line with an introduced Tet-responsive catalase transgene (MTOC2). We have previously reported that the overexpressed catalase in the MTOC2 cells reverses the malignant phenotype in part by decreasing epidermal growth factor receptor (EGFR) signaling. With this work we expanded the investigation into the differences between these two cell lines. We found that the decreased EGFR pathway activity of the MTOC2 cells is not because of reduced autocrine secretion of an epidermal growth factor (EGF) ligand but rather because of lower basal receptor activity. Phosphorylated levels of the mitogen-activated protein kinase (MAPK) members JNK and p38 were both higher in the 6M90 cells with low catalase when compared with the MTOC2 cell line. Although treatment with an EGFR inhibitor, AG1478, blocked the increased activity of JNK in the 6M90 cells, a similar effect was not observed for p38. Basal levels of downstream c-jun transcription were also found to be higher in the 6M90 cells versus MTOC2 cells. Activated p38 was found to down-regulate the JNK MAPK pathway in the 6M90 cells. However, the 6M90 cells contain constitutively high levels of phosphorylated JNK, generating higher levels of phosphorylated c-jun and total c-jun than those in the MTOC2 cells. Inhibition of JNK activity in the 6M90 cells reduced AP-1 transcription and cell proliferation. The data confirm the inhibitory effects of catalase on tumor cell growth, specifically through a ligand-independent decrease in the stress activated JNK pathway.

Reactive oxygen species in tumor metastasis

Tumor metastasis is attributed not only to the abnormalities of cancer cells, but also to changes induced by the interaction of cancer cells and surrounding cells/tissues. The host immune response to cancer cells may contribute to an increased incidence of tumor metastasis. Surgical removal of tumor tissues can trigger tumor recurrence and metastatic tumor growth in distant organs. An important class of molecules involved in these events is the reactive oxygen species (ROS), which have been identified as involved in not only to tumor metastasis but also most disease processes. ROS will contribute to various aspects of malignant tumors, including carcinogenesis, aberrant growth, metastasis, and angiogenesis. High-level ROS, which can be reached by several anti-cancer treatments, suppresses tumor metastasis by destroying cancer cells because of the oxidative nature of the molecules. On the other hand, sublethal levels of ROS can induce additional changes in DNA of tumor cells to make those cells malignant, stimulate the proliferation of cancer cells, and activate the expression of various molecules, some of which assist cancer cells to form metastatic colonies. Thus, a precise understanding how ROS are generated and involved in tumor metastasis will help us to design better strategies to overcome such life-threatening events.

Manganese superoxide dismutase enhances the invasive and migratory activity of tumor cells

Clinically significant elevations in the expression of manganese superoxide dismutase (Sod2) are associated with an increased frequency of tumor invasion and metastasis in certain cancers. The aim of this study was to examine whether increases in Sod2 activity modulate the migratory potential of tumor cells, contributing to their enhanced metastatic behavior. Overexpression of Sod2 in HT-1080 fibrosarcoma cells significantly enhanced their migration 2-fold in a wound healing assay and their invasive potential 3-fold in a transwell invasion assay. Severity of invasion was directly correlated to Sod2 expression levels and this invasive phenotype was similarly observed in 253J bladder tumor cells, in which Sod expression resulted in a 3-fold increase in invasion compared with controls. Further, migration and invasion of the Sod2-expressing cells was inhibited following overexpression of catalase, indicating that the promigratory/invasive phenotype of Sod2-expressing cells is H(2)O(2) dependent. Sod2 overexpression was associated with a loss of vinculin-positive focal adhesions that were recovered in cells coexpressing catalase. Tail vein injections of Sod2-GFP-expressing HT-1080 cells in NCR nude mice led to the development of pulmonary metastatic nodules displaying high Sod2-GFP expression. Isolated tumors were shown to retain high Sod2 activity in culture and elevated levels of the matrix degrading protein matrix metalloproteinase-1, and a promigratory phenotype was observed in a population of cells growing out from the tumor nodule. These findings suggest that the association between increased Sod2 activity and poor prognosis in cancer can be attributed to alterations in their migratory and invasive capacity.

Gene expression profiling in human gastric mucosa infected with Helicobacter pylori

Pathogenic mechanisms associated with Helicobacter pylori infection enhance susceptibility of the gastric epithelium to carcinogenic conversion. We have characterized the gene expression profiles of gastric biopsies from 69 French Caucasian patients, of which 43 (62%) were infected with H. pylori. The bacterium was detected in 27 of the 42 antral biopsies examined and in 16 of the 27 fundic biopsies. Infected biopsies were selected for the presence of chronic active gastritis, in absence of metaplasia and dysplasia of the gastric mucosa. Infected antral and fundic biopsies exhibited distinct transcriptional responses. Altered responses were linked with: (1) the extent of polymorphonuclear leukocyte infiltration, (2) bacterial density, and (3) the presence of the virulence factors vacA, babA2, and cagA. Robust modulation of transcripts associated with Toll-like receptors, signal transduction, the immune response, apoptosis, and the cell cycle was consistent with expected responses to Gram-negative bacterial infection. Altered expression of interferon-regulated genes (IFITM1, IRF4, STAT6), indicative of major histocompatibility complex (MHC) II-mediated and Th1-specific responses, as well as altered expression of GATA6, have previously been described in precancerous states. Upregulation of genes abundantly expressed in cancer tissues (UBD, CXCL13, LY96, MAPK8, MMP7, RANKL, CCL18) or in stem cells (IFITM1 and WFDC2) may reveal a molecular switch towards a premalignant state in infected tissues. Tissue microarray analysis of a large number of biopsies, which were either positive or negative for the cag-A virulence factor, when compared to each other and to noninfected controls, confirmed observed gene alterations at the protein level, for eight key transcripts. This study provides 'proof-of-principle' data for identifying molecular mechanisms driving H. pylori-associated carcinogenesis before morphological evidence of changes along the neoplastic progression pathway.

Oxidative stress in lymphocytes, neutrophils, and serum of oral cavity cancer patients: modulatory array of L-glutamine

OBJECTIVES

Our aim was to assess the oxidative stress and ameliorative effect of L-glutamine in serum, neutrophils, and lymphocytes of oral cancer patients by measuring the levels of malondialdehyde (MDA) and antioxidants.

MATERIALS AND METHODS

This study has been conducted on serum and specific blood cells in adult, male oral cancer patients (stage III-6, stage IV-42) and normal subjects of an equal number of age and sex-matched disease-free healthy subjects. The levels of lipid peroxidation and antioxidant enzymes were assayed using spectrophotometric methods.

RESULTS

MDA levels were elevated, and antioxidant enzyme status was decreased significantly in all groups of cancer patients simultaneously, but after supplementation of "glutammune" (66.66% L-glutamine), oxidative stress has been alleviated to some extent; especially, it has repaired the glutathione cascade system.

CONCLUSION

We conclude that oxidative stress is due to the enhanced lipid peroxidation and decrease in antioxidant enzymes, and it can be restored with dietary supplementation of L-glutamine related drug.

The signaling mechanism of ROS in tumor progression

Reactive oxygen species (ROS) are recently proposed to be involved in tumor metastasis which is a complicated processes including epithelial-mesenchymal transition (EMT), migration, invasion of the tumor cells and angiogenesis around the tumor lesion. ROS generation may be induced intracellularly, in either NADPH oxidase- or mitochondria-dependent manner, by growth factors and cytokines (such as TGFbeta and HGF) and tumor promoters (such as TPA) capable of triggering cell adhesion, EMT and migration. As a signaling messenger, ROS are able to oxidize the critical target molecules such as PKC and protein tyrosine phosphates (PTPs), which are relevant to tumor cell invasion. PKC contain multiple cysteine residues that can be oxidized and activated by ROS. Inactivation of multiple PTPs by ROS may relieve the tyrosine phosphorylation-dependent signaling. Two of the down-stream molecules regulated by ROS are MAPK and PAK. MAPKs cascades were established to be a major signal pathway for driving tumor cell metastasis, which are mediated by PKC, TGF-beta/Smad and integrin-mediated signaling. PAK is an effector of Rac-mediated cytoskeletal remodeling that is responsible for cell migration and angiogenesis. There are several transcriptional factors such as AP1, Ets, Smad and Snail regulating a lot of genes relevant to metastasis. AP-1 and Smad can be activated by PKC activator and TGF-beta1, respectively, in a ROS dependent manner. On the other hand, Est-1 can be upregulated by H2O2 via an antioxidant response element in the promoter. The ROS-regulated genes relevant to EMT and metastasis include E-cahedrin, integrin and MMP. Comprehensive understanding of the ROS-triggered signaling transduction, transcriptional activation and regulation of gene expressions will help strengthen the critical role of ROS in tumor progression and devising strategy for chemo-therapeutic interventions.

High-level expression and purification of recombinant human catalase in Pichia pastoris

Catalase is one of the antioxidant enzymes and is involved in many pathophysiologic processes and human diseases. This study focused on high-level expression and purification of recombinant catalase in Pichia pastoris. The cDNA encoding catalase was cloned by RT-PCR from Fetal liver of Homo sapiens. After PCR and construction of expression vector pPIC9K-CAT, human catalase was expressed highly in P. pastoris yeast SMD1168 and secreted into the culture medium. The secreted catalase was purified to a purity of 95% by ammonium sulfate fractionation, anionic exchange-chromatography, and Macro-prep Ceramic Hydroxyapatite with a overall yield of 60%. This study provides a new method for large-scale expression and purification of recombinant protein catalase.

Catalase reverses tumorigenicity in a malignant cell line by an epidermal growth factor receptor pathway

We have used a keratinocyte in vivo/in vitro cell model to test the hypothesis that hydrogen peroxide acts as a signaling molecule, contributing to proliferation and tumorigenesis. A cell line, 6M90, that produces squamous cell carcinoma (SCC), has high levels of ROS and low levels of catalase. A new cell line, MTOC2, generated from parental 6M90 cells by introduction of a Tet-responsive catalase transgene, effectively expressed higher peroxisomal catalase. Increased catalase expression diminished constitutive ROS and enhanced viability after treatment with hydrogen peroxide. Protein tyrosine phosphatase activity was higher in the MTOC2 cells with high catalase, consistent with detection of a lower level of phosphorylation at tyrosine 1068 of the epidermal growth factor receptor (EGF-R). Transcription of downstream c-fos, AP-1 transactivation and cell proliferation were higher in the low catalase cells. An EGF-R inhibitor, AG1478, blocks the higher AP-1 transactivation and cell proliferation of the low catalase 6M90 cells. Tumorigenesis in SCID mice was greatly diminished in the high catalase cells. Our data suggest that hydrogen peroxide functions as a signaling molecule that can modulate activity of a protein tyrosine phosphatase/(s) resulting in phosphorylation of tryrosine/(s) on the EGF-R. Therefore, catalase acts as a tumor-suppressor gene in part by decreasing EGF-R signaling.

Metastatic progression of pancreatic cancer: changes in antioxidant enzymes and cell growth

Pancreatic cancer has a dismal prognosis due to the fact that patients present late when metastatic disease is already present. Previous studies have demonstrated that pancreatic cancer cells have decreased levels of MnSOD, which correlates well with increased rates of tumor cell proliferation. Recently, we have found that nude mice injected with MIA PaCa-2 human pancreatic cancer cells in the flank occasionally develop ascites and intra-abdominal metastatic deposits. Mice that developed ascites were sacrificed and the ascites cultured. Necropsy demonstrated metastatic tumors in the retroperitoneum, which were excised, digested, and cultured. Western blots, enzyme activity and enzyme activity gels were performed for manganese superoxide dismutase (MnSOD), copper/zinc (CuZnSOD), catalase, and glutathione peroxidase (GPx) in the ascites cell line, metastatic tumor cell line, MIA PaCa-2 primary pancreatic cancer cell line, and the Capan-1, a metastatic pancreatic cancer cell line. Cell growth, plating efficiency, growth in soft agar and growth in nude mice were determined in the ascites, metastatic tumor, and MIA PaCa-2 cell lines. MnSOD, CuZnSOD, and GPx protein and activity were increased in the ascites, metastatic tumor, and Capan-1 cell lines compared to MIA PaCa-2. The ascites and metastatic tumor cell lines had decreased cell growth, plating efficiency, and growth in soft agar, but the ascites cell line had increased cell growth in 4 and 1% O(2) concentrations in vitro and more rapid growth in vivo. Metastatic disease is associated with changes in the content and activity of antioxidant enzymes with an associated change in growth characteristics depending on the O(2) concentrations.

Transcriptional repression of catalase in mouse skin tumor progression

Previous studies in our laboratory have shown that the elevation of reactive oxygen species levels and the repression of the antioxidant enzyme, catalase, played a critical role in the in vitro progression of benign papilloma cells to malignant carcinoma cells. Catalase message, protein levels, and activity levels were found to be downregulated in the malignantly progressed cells. The goal of this study is to further characterize the repression of catalase in malignant progression of mouse skin tumors. To validate the in vitro observations, we examined catalase expression in tumor samples generated by the multistep chemical carcinogenesis protocol. Higher levels of catalase mRNA and protein were observed in benign papillomas versus malignant carcinomas. Nuclear run-on analysis showed that catalase repression in the cultured malignant cells was transcription-dependent. Results from luciferase reporter assays indicated that malignant cells have lower catalase promoter activities than benign papilloma cells, in part through the Wilm's tumor suppressor 1 (WT1) binding site within the proximal promoter region. The WT1 protein levels were found to be inversely correlated with the observed catalase promoter activities, with higher levels observed in the malignant cells versus the benign cells. These results led us to conclude that WT1 is acting as a transcription repressor in catalase gene regulation during tumor progression.