Oxidative Stress Inducers in Cancer Therapy: Preclinical and Clinical Evidence

Reactive oxygen species (ROS) are metabolic byproducts that regulate various cellular processes. However, at high levels, ROS induce oxidative stress, which in turn can trigger cell death. Cancer cells alter the redox homeostasis to facilitate protumorigenic processes; however, this leaves them vulnerable to further increases in ROS levels. This paradox has been exploited as a cancer therapeutic strategy with the use of pro-oxidative drugs. Many chemotherapeutic drugs presently in clinical use, such as cisplatin and doxorubicin, induce ROS as one of their mechanisms of action. Further, various drugs, including phytochemicals and small molecules, that are presently being investigated in preclinical and clinical studies attribute their anticancer activity to ROS induction. Consistently, this review aims to highlight selected pro-oxidative drugs whose anticancer potential has been characterized with specific focus on phytochemicals, mechanisms of ROS induction, and anticancer effects downstream of ROS induction.

Iron imbalance in cancer: Intersection of deficiency and overload

Iron, an essential trace element, plays a complex role in tumour biology. While iron causes cancer clearance through toxic free radical generation, iron‐induced free radical flux also acts as a cancer promoter. These fates majorly guided through cellular response towards pro‐oxidant and antioxidant settings in a tumour microenvironment, designate iron‐induced oxidative stress as a common yet paradoxical factor in pro‐tumorigenesis as well as anti‐tumorigenesis, posing a challenge to laying down iron thresholds favouring tumour clearance. Additionally, complexity of iron's association with carcinogenesis has been extended to iron‐induced ROS's involvement in states of both iron deficiency and overload, conditions identified as comparable, inevitable and significant coexisting contributors as well as outcomes in chronic infections and tumorigenesis. Besides, iron overload may also develop as an unwanted outcome in certain cancer patients, as a result of symptomatic anaemia treatment owed to irrational iron‐restoration therapies without a prior knowledge of body's iron status with both conditions synergistically acting towards tumour aggravation. The co‐play of iron deficiency and overload along with iron's pro‐tumour and antitumour roles with intersecting mechanisms, thus presents an unpredictable regulatory response loop in a state of malignancy. The relevance of iron's thresholds beyond which it proves to be beneficial against tumorigenesis hence becomes questionable. These factors pose a challenge, over establishing if iron chelation or iron flooding acts as a better approach towards antitumour therapies. This review presents a critical picture of multiple contrasting features of iron's behaviour in cancer, leading towards two conditions lying at opposite ends of a spectrum: iron deficiency and overload in chronic disease conditions including cancer, hence, validating the critical significance of diagnosis of patients' iron status prior to opting for subsequent therapies.

Targeting Cellular Iron Homeostasis with Ironomycin in Diffuse Large B-cell Lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common hematological malignancy. Although more than half of patients with DLBCL achieve long-term remission, the majority of remaining patients succumb to the disease. As abnormal iron homeostasis is implicated in carcinogenesis and the progression of many tumors, we searched for alterations in iron metabolism in DLBCL that could be exploited to develop novel therapeutic strategies. Analysis of the iron metabolism gene expression profile of large cohorts of patients with DLBCL established the iron score (IS), a gene expression-based risk score enabling identification of patients with DLBCL with a poor outcome who might benefit from a suitable targeted therapy. In a panel of 16 DLBCL cell lines, ironomycin, a promising lysosomal iron-targeting small molecule, inhibited DLBCL cell proliferation at nanomolar concentrations compared with typical iron chelators. Ironomycin also induced significant cell growth inhibition, ferroptosis, and autophagy. Ironomycin treatment resulted in accumulation of DNA double-strand breaks, delayed progression of replication forks, and increased RPA2 phosphorylation, a marker of replication stress. Ironomycin significantly reduced the median number of viable primary DLBCL cells of patients without major toxicity for nontumor cells from the microenvironment and presented low toxicity in hematopoietic progenitors compared with conventional treatments. Significant synergistic effects were also observed by combining ironomycin with doxorubicin, BH3 mimetics, BTK inhibitors, or Syk inhibitors. Altogether, these data demonstrate that a subgroup of high-risk patients with DLBCL can be identified with the IS that can potentially benefit from targeting iron homeostasis.

SIGNIFICANCE

Iron homeostasis represents a potential therapeutic target for high-risk patients with DLBCL that can be targeted with ironomycin to induce cell death and to sensitize tumor cells to conventional treatments.

Alterations of Ion Homeostasis in Cancer Metastasis: Implications for Treatment

We have previously reported that metastases from all malignancies are characterized by a core program of gene expression that suppresses extracellular matrix interactions, induces vascularization/tissue remodeling, activates the oxidative metabolism, and alters ion homeostasis. Among these features, the least elucidated component is ion homeostasis. Here we review the literature with the goal to infer a better mechanistic understanding of the progression-associated ionic alterations and identify the most promising drugs for treatment. Cancer metastasis is accompanied by skewing in calcium, zinc, copper, potassium, sodium and chloride homeostasis. Membrane potential changes and water uptake through Aquaporins may also play roles. Drug candidates to reverse these alterations are at various stages of testing, with some having entered clinical trials. Challenges to their utilization comprise differences among tumor types and the involvement of multiple ions in each case. Further, adverse effects may become a concern, as channel blockers, chelators, or supplemented ions will affect healthy and transformed cells alike.

Iron: An Essential Element of Cancer Metabolism

Cancer cells undergo considerable metabolic changes to foster uncontrolled proliferation in a hostile environment characterized by nutrient deprivation, poor vascularization and immune infiltration. While metabolic reprogramming has been recognized as a hallmark of cancer, the role of micronutrients in shaping these adaptations remains scarcely investigated. In particular, the broad electron-transferring abilities of iron make it a versatile cofactor that is involved in a myriad of biochemical reactions vital to cellular homeostasis, including cell respiration and DNA replication. In cancer patients, systemic iron metabolism is commonly altered. Moreover, cancer cells deploy diverse mechanisms to increase iron bioavailability to fuel tumor growth. Although iron itself can readily participate in redox reactions enabling vital processes, its reactivity also gives rise to reactive oxygen species (ROS). Hence, cancer cells further rely on antioxidant mechanisms to withstand such stress. The present review provides an overview of the common alterations of iron metabolism occurring in cancer and the mechanisms through which iron promotes tumor growth.

Targeting ferroptosis in breast cancer

Ferroptosis is a recently discovered distinct type of regulated cell death caused by the accumulation of lipid-based ROS. Metabolism and expression of specific genes affect the occurrence of ferroptosis, making it a promising therapeutic target to manage cancer. Here, we describe the current status of ferroptosis studies in breast cancer and trace the key regulators of ferroptosis back to previous studies. We also compare ferroptosis to common regulated cell death patterns and discuss the sensitivity to ferroptosis in different subtypes of breast cancer. We propose that viewing ferroptosis-related studies from a historical angle will accelerate the development of ferroptosis-based biomarkers and therapeutic strategies in breast cancer.

Altered Iron Metabolism and Impact in Cancer Biology, Metastasis, and Immunology

Iron is an essential nutrient that plays a complex role in cancer biology. Iron metabolism must be tightly controlled within cells. Whilst fundamental to many cellular processes and required for cell survival, excess labile iron is toxic to cells. Increased iron metabolism is associated with malignant transformation, cancer progression, drug resistance and immune evasion. Depleting intracellular iron stores, either with the use of iron chelating agents or mimicking endogenous regulation mechanisms, such as microRNAs, present attractive therapeutic opportunities, some of which are currently under clinical investigation. Alternatively, iron overload can result in a form of regulated cell death, ferroptosis, which can be activated in cancer cells presenting an alternative anti-cancer strategy. This review focuses on alterations in iron metabolism that enable cancer cells to meet metabolic demands required during different stages of tumorigenesis in relation to metastasis and immune response. The strength of current evidence is considered, gaps in knowledge are highlighted and controversies relating to the role of iron and therapeutic targeting potential are discussed. The key question we address within this review is whether iron modulation represents a useful approach for treating metastatic disease and whether it could be employed in combination with existing targeted drugs and immune-based therapies to enhance their efficacy.

Microcellular Environmental Regulation of Silver Nanoparticles in Cancer Therapy: A Critical Review

Silver nanoparticles (AgNPs) play significant roles in various cancer cells such as functional heterogeneity, microenvironmental differences, and reversible changes in cell properties (e.g., chemotherapy). There is a lack of targets for processes involved in tumor cellular heterogeneity, such as metabolic clampdown, cytotoxicity, and genotoxicity, which hinders microenvironmental biology. Proteogenomics and chemical metabolomics are important tools that can be used to study proteins/genes and metabolites in cells, respectively. Chemical metabolomics have many advantages over genomics, transcriptomics, and proteomics in anticancer therapy. However, recent studies with AgNPs have revealed considerable genomic and proteomic changes, particularly in genes involved in tumor suppression, apoptosis, and oxidative stress. Metabolites interact biochemically with energy storage, neurotransmitters, and antioxidant defense systems. Mechanobiological studies of AgNPs in cancer metabolomics suggest that AgNPs may be promising tools that can be exploited to develop more robust and effective adaptive anticancer therapies. Herein, we present a proof-of-concept review for AgNPs-based proteogenomics and chemical metabolomics from various tumor cells with the help of several technologies, suggesting their promising use as drug carriers for cancer therapy.

Reclassifying Hepatic Cell Death during Liver Damage: Ferroptosis-A Novel Form of Non-Apoptotic Cell Death?

Ferroptosis has emerged as a new type of cell death in different pathological conditions, including neurological and kidney diseases and, especially, in different types of cancer. The hallmark of this regulated cell death is the presence of iron-driven lipid peroxidation; the activation of key genes related to this process such as glutathione peroxidase-4 (gpx4), acyl-CoA synthetase long-chain family member-4 (acsl4), carbonyl reductase [NADPH] 3 (cbr3), and prostaglandin peroxidase synthase-2 (ptgs2); and morphological changes including shrunken and electron-dense mitochondria. Iron overload in the liver has long been recognized as both a major trigger of liver damage in different diseases, and it is also associated with liver fibrosis. New evidence suggests that ferroptosis might be a novel type of non-apoptotic cell death in several liver diseases including non-alcoholic steatohepatitis (NASH), alcoholic liver disease (ALD), drug-induced liver injury (DILI), viral hepatitis, and hemochromatosis. The interaction between iron-related lipid peroxidation, cellular stress signals, and antioxidant systems plays a pivotal role in the development of this novel type of cell death. In addition, integrated responses from lipidic mediators together with free iron from iron-containing enzymes are essential to understanding this process. The presence of ferroptosis and the exact mechanisms leading to this non-apoptotic type of cell death in the liver remain scarcely elucidated. Recognizing ferroptosis as a novel type of cell death in the liver could lead to the understanding of the complex interaction between different types of cell death, their role in progression of liver fibrosis, the development of new biomarkers, as well as the use of modulators of ferroptosis, allowing improved theranostic approaches in the clinic.

Heme Oxygenase-1 Inhibits Tumor Metastasis Mediated by Notch1 Pathway in Murine Mammary Carcinoma

Heme oxygenase-1 (HO-1) plays an important role in the progression of several malignancies including breast cancer. However, its role in breast cancer metastasis is still ambiguous. In this study, we observed the effect of HO-1 on mouse mammary carcinoma metastasis using the in vivo tumor metastasis model. Our results revealed that overexpression of HO-1 strongly inhibits the lung metastasis of 4T1 cells. In in vitro analysis, associated indices for epithelial-mesenchymal transition (EMT), migration, and proliferation of 4T1 cells were evaluated. The results show that HO-1 inhibits EMT, migration, and proliferation of 4T1 cells. In addition, the Notch1/Slug pathway is found to mediate an antimetastasis role of HO-1 in mouse mammary carcinoma. In conclusion, since HO-1/Notch1/Slug axis plays an important role in breast cancer metastasis, induction of HO-1 could be used as a potential therapeutic strategy for breast cancer treatment.

Heme Oxygenase-1 Has an Antitumor Role in Breast Cancer

Aims: Heme oxygenase-1 (HO-1) is an enzyme involved in cellular responses to oxidative stress and has also been shown to regulate processes related to cancer progression. In this regard, HO-1 has been shown to display a dual effect with either antitumor or protumor activity, which is also true for breast cancer (BC). In this work, we address this discrepancy regarding the role of HO-1 in BC. Results: HO-1 was detected in human BC tissues, and its protein levels correlated with reduced tumor size and longer overall survival time of patients, thus suggesting the clinical importance of HO-1 in this type of cancer. Contrariwise, nuclear localization of HO-1 correlated with higher tumor grade suggesting that the effect of HO-1 is dependent on its cellular localization. In vivo experiments showed that both pharmacological activation and genetic overexpression of HO-1 reduce the tumor burden in two different animal models of BC. Furthermore, the pharmacological and genetic activation of HO-1 in several BC cell lines reduce the cellular viability by inducing apoptosis and cell cycle arrest and decrease the cellular migration and invasion rates by modulating pathways involved in the epithelial-mesenchymal transition. Furthermore, HO-1 activation impaired in vivo the metastatic dissemination. Innovation and Conclusion: By using various BC cell lines and animal models as well as human tumor samples, we demonstrated that total HO-1 displays antitumor activities in BC. Furthermore, our study suggests that HO-1 subcellular localization may explain the differential effects observed for the protein in different tumor types.

Can heme oxygenase-1 be a prognostic factor in patients with hepatocellular carcinoma?

Heme oxygenase-1 (HO-1) is an important catalytic enzyme in heme degradation, which increases during stressful conditions. It plays a major role in antioxidative and antiapoptotic processes and is associated with tumor growth and metastasis.This study aimed to evaluate the degree of HO-1 expressions in hepatocellular carcinoma (HCC) surgical specimens and the correlation between HO-1 expression and patient prognosis. Formalin-fixed, paraffin-embedded HCC tissue samples (n = 96) were included in the analysis, and the expression of HO-1 was evaluated by immunohistochemical staining. We reviewed clinical features of patients and evaluated the prognostic role of HO-1 in patient survival and recurrence.Positive HO-1 expression was identified in 43 cases (44.8%) and was frequently found in patients with advanced histology (Edmondson-Steiner [E-S] grade 2, 3, 4), α-fetoprotein (AFP) level of more than 200 IU/mL, and the presence of microvascular and capsular invasion (P < .05). In the univariate analysis, the overall survival (OS) and disease-free survival (DFS) of patients with HO-1-positive HCC were not statistically different from those with HO-1-negative HCC. Moreover, HO-1 expression was not associated with patient survival and recurrence based on the multivariate analysis. In the subgroup analysis of patients without preoperative transarterial chemoembolization (TACE) (n = 61), HO-1 was not also associated with tumor recurrence (P = .681).The clinical implication of HO-1 activity is controversial in various malignancies. However, HO-1 expression did not seem to influence the prognosis of HCC patients.

HO-1 is a favorable prognostic factor for HBV-HCC patients who underwent hepatectomy

Background

More than 500,000 people suffered from hepatocelluar carcinoma (HCC) annually and the relative incidence to mortality rate indicates its unfavorable prognosis. Several studies have proved that heme-oxygenase-1 (HO-1) is indirectly engaged in the invasion and the metastasis of some types of malignancies, including breast cancer, prostate cancer, and lung cancer. The role of HO-1 in hepatitis B virus (HBV)-related HCC is still not clarified.

Materials and methods

The Western blot, doubling time, cell cycle analysis, migration assay, invasion assay, gene transfection, xenograft animal model, immunohistochemistry staining, and clinical validation study were applied in this study.

Results

HO-1 overexpression not only decreased the growth but also inhibited the migration and invasion in human HBV-HCC cells (Hep-3B vs PLC/PRF/5). The inhibitory effect on growth, migration, and invasion is further demonstrated by the overexpression of HO-1 in Hep-3B cell by transfection study. Furthermore, HO-1 decreasing the growth of HBV-HCC was confirmed in animal study. The clinical validation illustrated that higher HO1 expression was also associated with favorable disease-free survival of HBV-HCC patients who underwent hepatectomy.

Conclusions

We identified HO-1 as a favorable prognostic factor for HBV-HCC patients who underwent hepatectomy.

Structural/Functional Matches and Divergences of Phytoprostanes and Phytofurans with Bioactive Human Oxylipins

Structure-activity relationship (SAR) constitutes a crucial topic to discover new bioactive molecules. This approach initiates with the comparison of a target candidate with a molecule or a collection of molecules and their attributed biological functions to shed some light in the details of one or more SARs and subsequently using that information to outline valuable application of the newly identified compounds. Thus, while the empiric knowledge of medicinal chemistry is critical to these tasks, the results retrieved upon dedicated experimental demonstration retrieved resorting to modern high throughput analytical approaches and techniques allow to overwhelm the constraints adduced so far to the successful accomplishment of such tasks. Therefore, the present work reviews critically the evidences reported to date on the occurrence of phytoprostanes and phytofurans in plant foods, and the information available on their bioavailability and biological activity, shedding some light on the expectation waken up due to their structural similarities with prostanoids and isoprostanes.

The standardized Korean Red Ginseng extract and its ingredient ginsenoside Rg3 inhibit manifestation of breast cancer stem cell-like properties through modulation of self-renewal signaling

Background

The ginsenoside Rg3, one of active components of red ginseng, has chemopreventive and anticancer potential. Cancer stem cells retain self-renewal properties which account for cancer recurrence and resistance to anticancer therapy. In our present study, we investigated whether the standardized Korean Red Ginseng extract (RGE) and Rg3 could modulate the manifestation of breast cancer stem cell–like features through regulation of self-renewal activity.

Methods

The effects of RGE and Rg3 on the proportion of CD44^high/CD24^low cells, as representative characteristics of stem-like breast cancer cells, were determined by flow cytometry. The mammosphere formation assay was performed to assess self-renewal capacities of breast cancer cells. Aldehyde dehydrogenase activity of MCF-7 mammospheres was measured by the ALDEFLUOR assay. The expression levels of Sox-2, Bmi-1, and P-Akt and the nuclear localization of hypoxia inducible factor-1α in MCF-7 mammospheres were verified by immunoblot analysis.

Results

Both RGE and Rg3 decreased the viability of breast cancer cells and significantly reduced the populations of CD44^high/CD24^low in MDA-MB-231 cells. RGE and Rg3 treatment attenuated the expression of Sox-2 and Bmi-1 by inhibiting the nuclear localization of hypoxia inducible factor-1α in MCF-7 mammospheres. Suppression of the manifestation of breast cancer stem cell–like properties by Rg3 was mediated through the blockade of Akt-mediated self-renewal signaling.

Conclusion

This study suggests that Rg3 has a therapeutic potential targeting breast cancer stem cells.

15-Deoxy-Δ12,14-prostaglandin J2 activates PI3K-Akt signaling in human breast cancer cells through covalent modification of the tumor suppressor PTEN at cysteine 136

15-Deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ₂), one of the terminal products of cyclooxygenase-2-catalized arachidonic acid metabolism, has been shown to stimulate breast cancer cell proliferation and migration through Akt activation, but the underlying mechanisms remain poorly understood. In the present study, we investigated the effects of 15d-PGJ₂ on the activity of PTEN, the inhibitor of the phosphoinositide 3-kinase (PI3K)-Akt axis, in human breast cancer (MCF-7) cells. Since the α,β-unsaturated carbonyl moiety in the cyclopentenone ring of 15d-PGJ₂ is electrophilic, we hypothesized that 15d-PGJ₂-induced Akt phosphorylation might result from the covalent modification and subsequent inactivation of PTEN that has several critical cysteine residues. When treated to MCF-7 cells, 15d-PGJ₂ bound to PTEN, and this was abolished in the presence of the thiol-reducing agent dithiothreitol. A mass spectrometric analysis by using recombinant and endogenous PTEN protein revealed that the cysteine 136 residue (Cys¹³⁶) of PTEN is covalently modified upon treatment with 15d-PGJ₂. Notably, the ability of 15d-PGJ₂ to covalently bind to PTEN as well as to induce Akt phosphorylation was abolished in the cells expressing a mutant form of PTEN in which Cys¹³⁶ was replaced by serine (C136S-PTEN). The present study demonstrates for the first time that electrophilic 15d-PGJ₂ directly binds to cysteine 136 of PTEN and provides new insight into PTEN loss in cancer progression associated with chronic inflammation. These observations suggest that 15d-PGJ₂ can undergo nucleophilic addition to PTEN, presumably at Cys¹³⁶, thereby inactivating this tumor suppressor protein with concomitant Akt activation.

4-Hydroxyestradiol induces mammary epithelial cell transformation through Nrf2-mediated heme oxygenase-1 overexpression

Estrogen (17β-estradiol, E₂) undergoes oxidative metabolism by CYP1B1 to form 4-hydroxyestradiol (4-OHE₂), a putative carcinogenic metabolite of estrogen. Our previous study showed that 4-OHE₂-induced production of reactive oxygen species contributed to neoplastic transformation of human breast epithelial (MCF-10A) cells. In this study, 4-OHE₂, but not E₂, increased the expression of heme oxygenase-1 (HO-1), a sensor and regulator of oxidative stress, in MCF-10A cells. Silencing the HO-1 gene in MCF-10A cells suppressed 4-OHE₂-induced cell proliferation and transformation. In addition, subcutaneous administration of 4-OHE₂ markedly enhanced the growth of the MDA-MB-231 human breast cancer xenografts, which was retarded by zinc protoporphyrin, a pharmacological inhibitor of HO-1. 4-OHE₂-induced HO-1 expression was mediated by NF-E2-related factor 2 (Nrf2). We speculate that an electrophilic quinone formed as a consequence of oxidation of 4-OHE₂ binds directly to Kelch-like ECH-associated protein 1 (Keap1), an inhibitory protein that sequesters Nrf2 in the cytoplasm. This will diminish association between Nrf2 and Keap1. 4-OHE₂ failed to interrupt the interaction between Keap1 and Nrf2 and to induce HO-1 expression in Keap1-C273S or C288S mutant cells. Lano-LC-ESI-MS/MS analysis in MCF-10A-Keap1-WT cells which were treated with 4-OHE₂ revealed that the peptide fragment containing Cys288 gained a molecular mass of 287.15 Da, equivalent to the addition of a single molecule of 4-OHE₂-derived ortho-quinones.

Heme oxygenase-1 retards hepatocellular carcinoma progression through the microRNA pathway

Heme metabolism system is involved in microRNA (miRNA) biogenesis. The complicated interplay between heme oxygenase-1 (HO-1) and miRNA has been observed in various tissues and diseases, including human malignancy. In the present study, our data showed that stable HO-1 overexpression in hepatocellular carcinoma (HCC) cells downregulated several oncomiRs. The most stably downregulated are miR-30d and miR-107. Iron, one of HO-1 catalytic products, was an important mediator in this regulation. Cell function analysis demonstrated that HO-1 inhibited the proliferation and metastasis of HepG2 cells, whereas miR-30d/miR-107 improved the proliferative and migratory ability of HepG2 cells. The beneficial effect of HO-1 in HCC inhibition could be reversed by upregulating miR-30d and miR-107. Akt and ERK pathways may be involved in the regulation of HO-1/miR-30d/miR-107 in HCC. These data indicate that HO-1 significantly suppresses HCC progression by regulating the miR-30d/miR-107 level, suggesting miR-30d/miR-107 regulation as a new molecular mechanism of HO-1 anticancer effect.

Epalrestat Upregulates Heme Oxygenase-1, Superoxide Dismutase, and Catalase in Cells of the Nervous System

Heme oxygenase (HO)-1 has potent antioxidant and anti-inflammatory functions. Recent studies have shown that the upregulation of HO-1 is beneficial to counteract neuroinflammation, making HO-1 a new therapeutic target for neurological diseases. We have reported that epalrestat (EPS), which is currently used for the treatment of diabetic neuropathy, increases HO-1 levels through the activation of nuclear factor erythroid 2-related factor 2 (Nrf2) in bovine aortic endothelial cells. In this study, we tested the hypothesis that EPS upregulates HO-1 via Nrf2 activation in the component cells of the nervous system, by using rat Schwann cells and human SH-SY5Y cells. Treatment of Schwann cells with EPS at near-plasma concentration led to a dramatic increase in HO-1 levels. Nrf2 knockdown by small interfering RNA (siRNA) suppressed the EPS-induced HO-1 expression. EPS did not promote the intracellular accumulation of free ferrous ion and reactive oxygen species, by increasing ferritin via Nrf2 during HO-1 induction. Moreover, EPS stimulated the expression of superoxide dismutase 1 and catalase, which also are Nrf2 target gene products. It also markedly increased HO-1 levels in SH-SY5Y cells through the activation of Nrf2. We demonstrated for the first time that EPS upregulates HO-1, superoxide dismutase, and catalase by activating Nrf2. We suggest that EPS has the potential to prevent several neurological diseases.

Haem oxygenase 1 expression is associated with prognosis in cholangiocarcinoma patients and with drug sensitivity in xenografted mice

OBJECTIVE

Haem oxygenase-1 (HO-1) plays important roles in cytoprotection and tumour growth. Cholangiocarcinoma (CCA) is a deadly malignancy with very poor prognosis. The role of HO-1 in tumour progression in CCA up to now has been relatively unexplored, thus, its possible therapeutic implications in CCA have been investigated here.

MATERIALS AND METHODS

HO-1 expression in tumour tissues from 50 CCA patients was determined by immunohistochemical analysis and its association with survival time was evaluated using the Kaplan-Meier method. Its role in CCA cells in vitro was evaluated by transwell and wound healing assays and suppression of HO-1 expression by siRNA. Effects of HO-1 inhibition on gemicitabine (GEM)-mediated tumour suppression was evaluated in nude mice xenografted with CCA cells.

RESULTS

HO-1 expression was inversely associated with median overall survival time. Hazard ratio of patients with high HO-1 expression was 2.42 (95% CI: 1.16-5.08) with reference to low expression and HO-1 knock-down expression inhibited transwell cell migration. Suppression of HO-1 by Zn-protoporphyrin (ZnPP) enhanced cytotoxicity to GEM in CCA cells, validated in CCA xenografts. Treatment with GEM and ZnPP almost completely arrested tumour growth, whereas treatment with only a single reagent, retarded it. Tumour inhibition was associated with reduction in expression of Ki-67 and microvascular density, and enhanced p53 and p21 immunohistochemical staining.

CONCLUSION

High HO-1 expression was associated with poor prognosis of CCA. Synergistic role of HO-1 inhibition in chemotherapy of CCA is a promising insight for treatment of this tumour and warrants further investigation.

HO-1/CO system in tumor growth, angiogenesis and metabolism - Targeting HO-1 as an anti-tumor therapy

Heme oxygenase-1 (HO-1, hmox-1) catalyzes the rate-limiting step in the heme degradation processes. Out of three by-products of HO-1 activity, biliverdin, iron ions and carbon monoxide (CO), the latter was mostly shown to mediate many beneficial HO-1 effects, including protection against oxidative injury, regulation of apoptosis, modulation of inflammation as well as contribution to angiogenesis. Mounting evidence suggests that HO-1/CO systemmay be of special benefit in protection inmany pathological conditions, like atherosclerosis or myocardial infarction. By contrast, the augmented expression of HO-1 in tumor tissues may have detrimental effect as HO-1 accelerates the formation of tumor neovasculature and provides the selective advantage for tumor cells to overcome the increased oxidative stress during tumorigenesis and during treatment. The inhibition of HO-1 has been proposed as an anti-cancer therapy, however, because of non-specific effects of known HO-1 inhibitors, the discovery of ideal drug lowering HO-1 expression/activity is still an open question. Importantly, in several types of cancer HO-1/CO system exerts opposite activities, making the possible treatment more complicated. All together indicates the complex role for HO-1/CO in various in vitro and in vivo conditions.

The role of cyclooxygenase-2, interleukin-1β and fibroblast growth factor-2 in the activation of matrix metalloproteinase-1 in sheared-chondrocytes and articular cartilage

MMP-1 expression is detected in fluid shear stress (20 dyn/cm²)-activated and osteoarthritic human chondrocytes, however, the precise mechanisms underlying shear-induced MMP-1 synthesis remain unknown. Using primary chondrocytes and T/C-28a2 chondrocytic cells as model systems, we report that prolonged application of high fluid shear to human chondrocytes induced the synthesis of cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β) and fibroblast growth factor-2 (FGF-2), which led to a marked increase in MMP-1 expression. IL-1β, COX-2-dependent PGE₂ activated the PI3-K/AKT and p38 signaling pathways, which were in turn responsible for MMP-1 synthesis via NF-κB- and c-Jun-transactivating pathways. Prolonged shear stress exposure (>12 h) induced 15-Deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ₂) synthesis. Although 15d-PGJ₂ suppressed PI3-K/AKT and p38 signaling pathways, it stimulated MMP-1 expression via activating heme oxygenase 1 (HO-1). The critical role of COX-2 in regulating MMP-1 expression in articular cartilage in vivo was demonstrated using COX-2^+/− transgenic mice in the absence or presence of rofecoxib oral administration. These findings provide novel insights for developing therapeutic strategies to combat OA.

15-deoxy-δ12,14-prostaglandin j2 inhibits osteolytic breast cancer bone metastasis and estrogen deficiency-induced bone loss

Breast cancer is the major cause of cancer death in women worldwide. The most common site of metastasis is bone. Bone metastases obstruct the normal bone remodeling process and aberrantly enhance osteoclast-mediated bone resorption, which results in osteolytic lesions. 15-deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ₂) is an endogenous ligand of peroxisome proliferator-activated receptor gamma (PPARγ) that has anti-inflammatory and antitumor activity at micromolar concentrations through PPARγ-dependent and/or PPARγ-independent pathways. We investigated the inhibitory activity of 15d-PGJ₂ on the bone loss that is associated with breast cancer bone metastasis and estrogen deficiency caused by cancer treatment. 15d-PGJ₂ dose-dependently inhibited viability, migration, invasion, and parathyroid hormone-related protein (PTHrP) production in MDA-MB-231 breast cancer cells. 15d-PGJ₂ suppressed receptor activator of nuclear factor kappa-B ligand (RANKL) mRNA levels and normalized osteoprotegerin (OPG) mRNA levels in hFOB1.19 osteoblastic cells treated with culture medium from MDA-MB-231 cells or PTHrP, which decreased the RANKL/OPG ratio. 15d-PGJ₂ blocked RANKL-induced osteoclastogenesis and inhibited the formation of resorption pits by decreasing the activities of cathepsin K and matrix metalloproteinases, which are secreted by mature osteoclasts. 15d-PGJ₂ exerted its effects on breast cancer and bone cells via PPARγ-independent pathways. In Balb/c nu/nu mice that received an intracardiac injection of MDA-MB-231 cells, subcutaneously injected 15d-PGJ₂ substantially decreased metastatic progression, cancer cell-mediated bone destruction in femora, tibiae, and mandibles, and serum PTHrP levels. 15d-PGJ₂ prevented the destruction of femoral trabecular structures in estrogen-deprived ICR mice as measured by bone morphometric parameters and serum biochemical data. Therefore, 15d-PGJ₂ may be beneficial for the prevention and treatment of breast cancer-associated bone diseases.

Novel imidazole derivatives as heme oxygenase-1 (HO-1) and heme oxygenase-2 (HO-2) inhibitors and their cytotoxic activity in human-derived cancer cell lines

Heme oxygenase (HO) is a cytoprotective enzyme that can be overexpressed in some pathological conditions, including certain cancers. In this work, novel imidazole derivatives were designed and synthesized as inhibitors of heme oxygenase-1 (HO-1) and heme oxygenase-2 (HO-2). In these compounds the imidazole ring, crucial for the activity, is connected to a hydrophobic group, represented by aryloxy, benzothiazole, or benzoxazole moieties, by means of alkyl or thioalkyl chains of different length. Many of the tested compounds were potent and/or selective against one of the two isoforms of HO. Furthermore, most of the pentyl derivatives showed to be better inhibitors of HO-2 with respect to HO-1, revealing a critical role of the alkyl chain in discriminating between the two isoenzymes. Compounds which showed the better profile of HO inhibition were selected and tested to evaluate their cytotoxic properties in prostate and breast cancer cell lines (DU-145, PC3, LnCap, MDA-MB-231, and MCF-7). In these assays, aryloxyalkyl derivatives resulted more cytotoxic than benzothiazolethioalkyl ones; in particular compound 31 was active against all the cell lines tested, confirming the anti-proliferative properties of HO inhibitors and their potential use in the treatment of specific cancers.

Lipocalin-2 enhances angiogenesis in rat brain endothelial cells via reactive oxygen species and iron-dependent mechanisms

Inflammation is a key part of central nervous system pathophysiology. However, inflammatory factors are now thought to have both beneficial and deleterious effects. Here, we examine the hypothesis that lipocalin-2 (LCN2), an inflammatory molecule that can be up-regulated in the distressed central nervous system, may enhance angiogenesis in brain endothelial cells. Adding LCN2 (0.5-2.0 μg/mL) to RBE (Rat brain endothelial cells). 4 rat brain endothelial cells significantly increased matrigel tube formation and scratch migration, and also elevated levels of iron and reactive oxygen species. Co-treatment with a radical scavenger (U83836E), a Nox inhibitor (apocynin) and an iron chelating agent (deferiprone) significantly dampened the ability of LCN2 to enhance tube formation and scratch migration in brain endothelial cells. These findings provide in vitro proof of the concept that LCN2 can promote angiogenesis via iron- and reactive oxygen species-related pathways, and support the idea that LCN2 may contribute to the neurovascular recovery aspects of inflammation. Angiogenesis is an important part of stroke recovery. In the present study, we examined the hypothesis that lipocalin-2 (LCN2) may enhance angiogenesis in brain endothelial cells. LCN2 promoted tube formation and migration via iron and ROS-related pathways in rat brain endothelial cells. ROS scavengers, Nox inhibitors and iron chelators all dampened the ability of LCN2 to enhance in vitro angiogenesis. These findings support the idea that LCN2 that is released by damaged neurons may act as a 'help me' signal that promotes neurovascular recovery after stroke and brain injury.

15-Deoxy-Δ12,14-prostaglandin J2 induces expression of 15-hydroxyprostaglandin dehydrogenase through Elk-1 activation in human breast cancer MDA-MB-231 cells

Overproduction of prostaglandin E2 (PGE2) has been reported to be implicated in carcinogenesis. The intracellular level of PGE2 is maintained not only by its biosynthesis, but also by inactivation/degradation. 15-Hydroxyprostaglandin dehydrogenase (15-PGDH) is the key enzyme that catalyzes the conversion of oncogenic PGE2 to a biologically inactive keto metabolite. In the present study, we demonstrate that 15-deoxy-Δ(12,14)-prostaglandin J2 (15 d-PGJ2), one of the terminal products of cyclooxygenase-2, updregulates the expression and the activity of 15-PGDH in human breast cancer MDA-MB-231 cells. By using deletion constructs of the 15-PGDH promoter, we have found that E-twenty six (Ets) is the most essential determinant for 15-PGDH induction. 15 d-PGJ2 induced phosphorylation of Elk-1, one of Ets transcription factor family members, in the nucleus. Knockdown of Elk-1 abolished the ability of 15 d-PGJ2 to upregulate 15-PGDH expression. Furthermore, 15 d-PGJ2-mediated activation of Elk-1 was found to be dependent on activation of extracellular-signal related kinase (ERK) 1/2. Treatment of U0126, a pharmacological inhibitor of MEK1/2-ERK, abolished phosphorylation and DNA binding of Elk-1 as well as 15-PGDH induction in 15 d-PGJ2-treated MDA-MB-231 cells. Moreover, 15 d-PGJ2 generated reactive oxygen species (ROS), which contribute to the expression of 15-PGDH as well as phosphorylation of ERK1/2 and Elk-1. 15 d-PGJ2 inhibited the migration of MDA-MB-231 cells, which was attenuated by transient transfection with 15-PGDH siRNA. Taken together, these findings suggest that 15 d-PGJ2 induces the expression of 15-PGDH through ROS-mediated activation of ERK1/2 and subsequently Elk-1 in the MDA-MB-231 cells, which may contribute to tumor suppressive activity of this cyclopentenone prostaglandin.

Do iron chelators increase the antiproliferative effect of trichostatin A through a glucose-regulated protein 78 mediated mechanism?

Histone deacetylase (HDAC) inhibitors, such as trichostatin A (TSA), and iron chelators, including deferoxamine (DFO) and phenanthroline (PHEN), appear to have anticancer effects. We hypothesized that the HDAC inhibitors and iron chelators would be synergistic with their effect on breast cancer cell line MCF7, because the HDAC inhibitors increase glucose-regulated protein 78 (Grp78) and the iron chelators reduce its expression. Although the administration of TSA alone resulted in a dose-related decrease in the cell index, it did not have an antiproliferative effect except the 62.5 and 500 nM of TSA. However, all doses of TSA produced a cytotoxic effect from the initial hours when combined with 150 μM of DFO and 25 μM of PHEN. DFO and PHEN downregulated Grp78, Grp94, and MRP1 expressions and upregulated CHOP and HO-1 expressions. TSA upregulated all the genes in various rates when used alone but resulted in decreased expression levels when combined with DFO and PHEN. Increased HDAC-1 levels in the Grp78 promoter region indicated that DFO and PHEN either promoted binding of HDAC-1 to this region or inhibited its detachment. We determined that the reduction of increased Grp78, Grp94, HO-1, and MRP1 expressions, which appears to inhibit the chemotherapeutic effect of TSA, through the combination with DFO or PHEN will contribute to the anticancer effect.

Oncogenic potential of Nrf2 and its principal target protein heme oxygenase-1

Nuclear factor erythroid 2-related factor 2 (Nrf2) is an essential component of cellular defense against a vast variety of endogenous and exogenous insults, including oxidative stress. Nrf2 acts as a master switch in the circuits upregulating the expression of various stress-response proteins, especially heme oxygenase-1 (HO-1). Paradoxically, however, recent studies have demonstrated oncogenic functions of Nrf2 and its major target protein HO-1. Levels of Nrf2 and HO-1 are elevated in many different types of human malignancies, which may facilitate the remodeling of the tumor microenvironment making it advantageous for the autonomic growth of cancer cells, metastasis, angiogenesis, and tolerance to chemotherapeutic agents and radiation and photodynamic therapy. In this context, the cellular stress response or cytoprotective signaling mediated via the Nrf2-HO-1 axis is hijacked by cancer cells for their growth advantage and survival of anticancer treatment. Therefore, Nrf2 and HO-1 may represent potential therapeutic targets in the management of cancer. This review highlights the roles of Nrf2 and HO-1 in proliferation of cancer cells, their tolerance/resistance to anticancer treatments, and metastasis or angiogenesis in tumor progression.

The role of peroxisome proliferator-activated receptors in colorectal cancer

Colorectal cancer is one of the most common cancers in the world. Dietary fat intake is a major risk factor for colorectal cancer. Some nuclear hormone receptors play an important role in regulating nutrient metabolism and energy homeostasis. Among these receptors, special attention has been focused on the role of peroxisome proliferator-activated receptors (PPARs) in colorectal cancer, because PPARs are involved in regulation of lipid and carbohydrate metabolism. PPARs are ligand-activated intracellular transcription factors. The PPAR subfamily consists of three subtypes encoded by distinct genes named PPARα, PPARβ/δ, and PPARγ. PPARγ is the most extensively studied subtype of PPARs. Even though many investigators have studied the expression and clinical implications of PPARs in colorectal cancer, there are still many controversies about the role of PPARs in colorectal cancer. In this paper, the recent progresses in understanding the role of PPARs in colorectal cancer are summarized.

15-deoxy-Δ¹²,¹⁴ -prostaglandin J₂ inhibits human immunodeficiency virus-1 tat-induced monocyte chemoattractant protein-1/CCL2 production by blocking the extracellular signal-regulated kinase-1/2 signaling pathway independently of peroxisome proliferator-activated receptor-γ and heme oxygenase-1 in rat hippocampal slices

Human immunodeficiency virus (HIV)-induced inflammation, and its consequences within the central nervous system (CNS), must be countered by multiple pharmacologic agents, and 15-deoxy-Δ(12,14) -prostaglandin J(2) (15d-PGJ2) may hold promise in the treatment of pathologies associated with this inflammatory response. 15d-PGJ2 can repress the inflammatory response by means of peroxisome proliferator-activated receptor-γ (PPARγ)-dependent and -independent mechanisms. However, its precise role and antiinflammatory mechanism in the hippocampus remain poorly understood. In the present study, rat hippocampal slices were stimulated with full-length HIV-1 Tat protein to investigate the role of 15d-PGJ2 8in the hippocampal inflammatory response. Pretreatment of slices with 15d-PGJ2 markedly reduced Tat-induced monocyte chemoattractant protein-1 (MCP-1/CCL2) production. Interestingly, the PPARγ antagonist GW9662 did not inhibit action of 15d-PGJ2, confirming the latter's PPARγ-independent mechanism of mediating antiinflammatory effects. Despite 15d-PGJ2's increasing the expression of heme oxygenase-1 (HO-1), its action was not abrogated by the HO-1 inhibitor zinc protoporphyrin IX (ZnPPIX), nor was it recapitulated by HO-1 inducers such as cobalt protoporphyrin (CoPP). Moreover, short interfering RNA (siRNA)-directed knockdown of HO-1 did not abolish the antiinflammatory action of 15d-PGJ2 against Tat-induced MCP-1 production in human microglia-like THP-1 cells. Conversely, 15d-PGJ2 suppressed Tat-induced ERK1/2 activation, decreasing MCP-1 production upon Tat stimulation. The NADPH oxidase inhibitors DPI and apocynin also abrogated Tat-stimulated ERK1/2 activation, reducing MCP-1 production. Collectively, these data demonstrate that the antiinflammatory effects of 15d-PGJ2 on the hippocampus are exerted through inhibition of Tat-mediated ERK1/2 activation, coupled with that of a redox-sensitive pathway, independent of PPARγ and HO-1.

Curcumin-induced heme oxygenase-1 expression plays a negative role for its anti-cancer effect in bladder cancers

Some phytochemicals with the characteristics of cytotoxicity and anti-metastasis has generated intense interest among the invasive cancer study. Curcumin, one of these anti-cancer phytochemicals, has been reported to induce the cytoprotective enzyme heme oxygenase-1 expression. Since heme oxygenase-1 has been suggested to enhance cancer cell invasion, we investigated the anti-invasive effect of curcumin when heme oxygenase-1 was knocked down in vitro, and the heme oxygenase-1 expression after curcumin treatment in vivo. Curcumin inhibited cell viability and the MMP-2/9 activities of human bladder cancer cells. At 10 μM, curcumin inhibited cell viability and cell invasive activity by 15% and 40%, respectively. Ten micrometer curcumin increased the intracellular reactive oxygen species concentration and heme oxygenase-1 protein and mRNA expression in bladder cancer cells. The anti-invasive activity of curcumin was elevated when heme oxygenase-1 was knocked down by siRNA or inhibited by pharmacological inhibitor. In vivo, curcumin induced heme oxygenase-1 protein expression in the lung tissue of murine lung metastasis tumor model and in the bladder tissue of murine orthotopic bladder tumor model. Taken together, our data suggest that curcumin-induced heme oxygenase-1 attenuates the anti-invasive effect of curcumin in cancer therapy, and co-treatment by heme oxygenase-1 inhibitor enhances the anti-invasive activity of curcumin.

Emerging avenues linking inflammation and cancer

The role of inflammation in carcinogenesis has been extensively investigated and well documented. Many biochemical processes that are altered during chronic inflammation have been implicated in tumorigenesis. These include shifting cellular redox balance toward oxidative stress; induction of genomic instability; increased DNA damage; stimulation of cell proliferation, metastasis, and angiogenesis; deregulation of cellular epigenetic control of gene expression; and inappropriate epithelial-to-mesenchymal transition. A wide array of proinflammatory cytokines, prostaglandins, nitric oxide, and matricellular proteins are closely involved in premalignant and malignant conversion of cells in a background of chronic inflammation. Inappropriate transcription of genes encoding inflammatory mediators, survival factors, and angiogenic and metastatic proteins is the key molecular event in linking inflammation and cancer. Aberrant cell signaling pathways comprising various kinases and their downstream transcription factors have been identified as the major contributors in abnormal gene expression associated with inflammation-driven carcinogenesis. The posttranscriptional regulation of gene expression by microRNAs also provides the molecular basis for linking inflammation to cancer. This review highlights the multifaceted role of inflammation in carcinogenesis in the context of altered cellular redox signaling.

The glutathionylation of p65 modulates NF-κB activity in 15-deoxy-Δ¹²,¹⁴-prostaglandin J₂-treated endothelial cells

Protein glutathionylation is a posttranslational modification of cysteine residues with glutathione in response to mild oxidative stress. Because 15-deoxy-Δ12,14-prostaglandin J(2) (15d-PGJ(2)) is an electrophilic prostaglandin that can increase glutathione (GSH) levels and augment reactive oxygen species (ROS) production, we hypothesized that it induces NF-κB-p65 glutathionylation and would exert anti-inflammatory effects. Herein, we show that 15d-PGJ(2) suppresses the expression of ICAM-1 and NF-κB-p65 nuclear translocation. 15d-PGJ(2) upregulates the Nrf2-related glutathione synthase gene and thereby increases the GSH levels. Consistent with this, Nrf2 siRNA molecules abolish the inhibition of p65 nuclear translocation in 15d-PGJ(2)-induced endothelial cells (ECs). ECs treated with GSSG show increased thiol modifications of p65 and also a block in TNFα-induced p65 nuclear translocation and ICAM-1 expression, but not in IκBα degradation. However, the overexpression of glutaredoxin 1 was found to be accompanied by a modest increase in NF-κB activity. Furthermore, we found that multiple cysteine residues in p65 are responsible for glutathionylation. 15d-PGJ(2) was observed to induce p65 glutathionylation and is suppressed by a GSH synthesis inhibitor, buthionine sulfoximine, by catalase, and by Nrf2 siRNA molecules. Our results thus indicate that the GSH/ROS-dependent glutathionylation of p65 is likely to be responsible for 15d-PGJ(2)-mediated NF-κB inactivation and for the enhanced inhibitory effects of 15d-PGJ(2) on TNFα-treated ECs.

Role of the Nrf2-heme oxygenase-1 pathway in silver nanoparticle-mediated cytotoxicity

Silver nanoparticles (nano-Ag) have been widely used in various commercial products including textiles, electronic appliances and biomedical products. However, there remains insufficient information on the potential risk of nano-Ag to human health and environment. In the current study, we have investigated the role of NF-E2-related factor 2 (Nrf2) transcription factor in nano-Ag-induced cytotoxicity. When Nrf2 expression was blocked using interring RNA expression in ovarian carcinoma cell line, nano-Ag treatment showed a substantial decrease in cell viability with concomitant increases in apoptosis and DNA damage compared to the control cells. Target gene analysis revealed that the expression of heme oxygenase-1 (HO-1) was highly elevated by nano-Ag in nonspecific shRNA expressing cells, while Nrf2 knockdown cells (NRF2i) did not increase HO-1 expression. The role of HO-1 in cytoprotection against nano-Ag was reinforced by results using pharmacological inducer of HO-1: cobalt protoporphyrin-mediated HO-1 activation in the NRF2i cells prevented nano-Ag-mediated cell death. Similarly, pharmacological or genetic inhibition of HO-1 in nonspecific control cells exacerbated nano-Ag toxicity. As the upstream signaling mechanism, nano-Ag required the phosphoinositide 3-kinase (PI3K) and p38MAPK signaling cascades for HO-1 induction. The treatment with either PI3K inhibitor or p38MAPK inhibitor suppressed HO-1 induction and intensified nano-Ag-induced cell death. Taken together, these results suggest that Nrf2-dependent HO-1 up-regulation plays a protective role in nano-Ag-induced DNA damage and consequent cell death. In addition, nano-Ag-mediated HO-1 induction is associated with the PI3K and p38MAPK signaling pathways.

Heme oxygenase-1: a molecular brake on hepatocellular carcinoma cell migration

Hepatocellular carcinoma (HCC) is a fatal disease with great public health impact worldwide. Heme oxygenase (HO)-1 has recently been reported as an important player in tumor angiogenesis and metastasis. However, the role of HO-1 in liver cancer metastasis is unclear. In this study, we explored genetic differences and downstream signal transduction pathways of HO-1 in liver cancer cell lines. HO-1 wild-type and mutant cell lines were generated from human liver cancer cell line HepG2. The overexpression of wild-type HO-1 decreased the migration of HepG2 cells. In contrast, the overexpression of mutant HO-1G143H increased the migration of the cancer cells. Interleukin (IL)-6 is one of the major downstream molecules that mediated this process because IL-6 expression and migration are suppressed by HO-1 and increased when HO-1 is knocked down by shRNA. In addition, we demonstrated carbon monoxide (CO) and p38MAPK are the cofactors in this signal pathway. In vivo animal model demonstrated HO-1 inhibited the tumor growth. In conclusion, in vitro and in vivo data show HO-1 inhibits the human HCC cells migration and tumor growth by suppressing the expression of IL-6. The heme degradation product CO is a cofactor in this process and inhibits p38MAPK phosphorylation.

Inflammation-related signaling pathways implicating TGFβ are revealed in the expression profiling of MCF7 cell treated with fermented soybean, chungkookjang

Chungkookjang is a Korean fermented soybean containing microorganisms, proteinase, and diverse bioactive compounds, including a high concentration of isoflavones and peptides. Growth of breast cancer MCF7 cells decreased dependent on the concentration of fermented soybean extracts. The effect of fermented soybean on cellular gene expression was determined in a systematic manner comprehensively. DNA microarray analysis was performed using 25,804 probes. Ninety one genes whose expression levels were significantly changed were selected. TGFβI and Smad3 were upregulated. Downregulation of inflammation-related CSF2, CSF2RA, and CSF3 was found. Differential expression of chemokines CCL2, CCL3, CCL3L3, CXCL1, and CXCL2 were observed. Network analysis identified ERβ in the network. Based on the experimental results, taking fermented soybean might be helpful for preventing breast cancer by a mechanism activating TGFβ pathway and depressing inflammation.

Resveratrol inhibits human lung adenocarcinoma cell metastasis by suppressing heme oxygenase 1-mediated nuclear factor-kappaB pathway and subsequently downregulating expression of matrix metalloproteinases

Resveratrol exhibits potential anti-carcinogenic activities. Heme oxygenase-1 (HO-1) is involved in angiogenesis and tumor metastasis. Matrix metalloproteinases (MMPs) are key enzymes in the degradation of extracellular matrix, and their expression may be dysregulated in lung cancer metastasis. In this study, we investigated the anti-invasive mechanism of resveratrol in lung cancer cells. HO-1 was shown to be elevated (approximately 4.7-fold) in lung cancer tumor samples as compared with matched normal tissues. After treatment of lung adenocarcinoma cell line A549 cells with resveratrol (50 microM) for 24 h, the migratory and invasive abilities (38 and 30% inhibition, respectively) of A549 cells were significantly reduced. Resveratrol significantly inhibited HO-1-mediated MMP-9 (35% inhibition) and MMP-2 (28% inhibition) expression in lung cancer cells. Nuclear factor (NF)-kappaB inhibitor induced a marked reduction in MMP-9 and MMP-2 expression, suggesting NF-kappaB pathway could play an important role. Furthermore, HO-1 inhibition and silencing significantly suppressed MMPs and invasion of lung cancer cells. Our results suggest that resveratrol inhibited HO-1 and subsequently MMP-9 and MMP-2 expression in lung cancer cells. The inhibitory effects of resveratrol on MMP expression and invasion of lung cancer cells are, in part, associated with the HO-1-mediated NF-kappaB pathway.

Gene expression profile and cytotoxicity of human bronchial epithelial cells exposed to crotonaldehyde

Crotonaldehyde is an environment pollutant and lipid peroxidation product. Crotonaldehyde produces adverse effects to humans and serves as a risk factor for human pulmonary diseases. Like acrolein and 4-hydroxynonenal, crotonaldehyde seems likely to alter many cell signaling cascades, including inflammatory responses. The purpose of this study was to investigate the genome-wide transcriptional responses of normal human bronchial epithelial cells exposed to crotonaldehyde. Using microarrays technology, the global changes in transcriptional level were analyzed. Prior to RNA extraction, cells were exposed to crotonaldehyde at 40 or 80 microM for 3 or 6h. Real-time quantitative polymerase chain reaction (qPCR) was performed to validate microarray data and cell cycle arrest was determined. The commonly differentially regulated genes in many biological processes were dysregulated including inflammatory responses, exogenous metabolism, cell cycle, heat shock responses, and antioxidant responses. Results in the present study screen out the important roles of HMOX1 in regulating other signaling cascades and ALDH1A3 in detoxifying exogenous toxicants. Collectively, our study demonstrated that crotonaldehyde altered gene expression profile in the genome-wide transcriptional level in normal human bronchial epithelial cells. And many of them represented potential mechanisms of crotonaldehyde causing cytotoxicity and tissue injury in the human lung.

Nrf2-Keap1 signaling as a potential target for chemoprevention of inflammation-associated carcinogenesis

Persistent inflammatory tissue damage is causally associated with each stage of carcinogenesis. Inflammation-induced generation of reactive oxygen species, reactive nitrogen species, and other reactive species not only cause DNA damage and subsequently mutations, but also stimulate proliferation of initiated cells and even metastasis and angiogenesis. Induction of cellular cytoprotective enzymes (e.g., heme oxygenase-1, NAD(P)H:quinone oxidoreductase, superoxide dismutase, glutathione-S-transferase, etc.) has been shown to mitigate aforementioned events implicated in inflammation-induced carcinogenesis. A unique feature of genes encoding these cytoprotective enzymes is the presence of a cis-acting element, known as antioxidant response element (ARE) or electrophile response element (EpRE), in their promoter region. A stress-responsive transcription factor, nuclear factor erythroid-2-related factor-2 (Nrf2), initially recognized as a key transcriptional regulator of various cytoprotective enzymes, is known to play a pivotal role in cellular defense against inflammatory injuries. Activation of Nrf2 involves its release from the cytosolic repressor Kelch-like ECH-associated protein-1 (Keap1) and subsequent stabilization and nuclear localization for ARE/EpRE binding. Genetic or pharmacologic inactivation of Nrf2 has been shown to abolish cytoprotective capability and to aggravate experimentally induced inflammatory injuries. Thus, Nrf2-mediated cytoprotective gene induction is an effective strategy for the chemoprevention of inflammation-associated carcinogenesis.

Pivotal Advance: Heme oxygenase 1 expression by human CD4+ T cells is not sufficient for their development of immunoregulatory capacity

HO-1 is the only inducible one of three isoenzymes that catalyzes the oxidative degradation of heme. HO-1 is inducible by various cellular stress factors and exerts cytoprotective and immunomodulatory effects. Recent publications demonstrated that HO-1 is constitutively expressed by CD4(+)CD25(+) T(regs) and induced in CD4(+)CD25(-) T cells upon FoxP3 transfection. Here, we investigated whether HO-1 was essential and sufficient for human T(regs) to exert immunosuppression in vitro. PGJ(2) induced pronounced expression of HO-1 in CD4(+)CD25(-) T cells without accompanying FoxP3 induction. Treatment of CD4(+)CD25(-) T cells with PGJ(2) decreased their proliferation, whereas the HO-1 inhibitor SnPP enhanced the proliferation of HO-1-expressing T(regs), suggesting that HO-1 may modulate the proliferative capacity of T lymphocytes. HO-1 modulation by SnPP treatment of T(regs) or PGJ(2) treatment of CD4(+)CD25(-) T cells neither suppressed nor induced immune-modulatory function in these cells, respectively, as measured by responder-cell proliferation and/or IL-2 production. In summary, these data suggest that HO-1 expression by T(regs) might contribute to their typical reluctance to proliferate but does not account independently for their suppressive functions.