The effects of the inhibition of inducible nitric oxide synthase on angiogenesis of epithelial ovarian cancer

The potential benefits of dinitrophenol combination with chemotherapy in the treatment of ovarian cancer

BACKGROUND

2,4-dinitrophenol (DNP), an uncoupling mitochondrial agent, has been identified as a source of oxidative stress and linked to the pathogenesis of ovarian cancer. In this study, we determine the cytotoxic effect of DNP alone or in combination with chemotherapies in ovarian cancer cells.

METHODS

We utilized human ovarian cancer cell lines SKOV-3 and MDAH-2774 with their chemoresistant counterparts. Cancer stem cells (CSCs) were isolated from SKOV-3 utilizing magnetic-activated cell sorting technique for CD44+/CD117+ cells. Human normal primary ovarian epithelial (NOEC) and HOSEpiC cell lines were used as a control. Cells were treated with and without chemotherapy (taxotere 0.3 µM or cisplatin 50 µM), with or without increasing doses of DNP (0.125, 0.25, or 0.5 mM) for 24 hours followed by evaluation of cell viability and IC50 utilizing MTT assay. For determination of synergism, Fa-combination Index plots were created using the CompuSyn software (ComboSyn, Inc., Paramus, NJ, USA). All data were run in triplicates and analyzed by t-test.

RESULTS

DNP treatment of ovarian cancer and chemoresistant ovarian cancer cell lines as well as CSCs resulted in decreased cell viability in a dose dependent manner with no effect on normal cells. Combination of DNP with chemotherapy synergistically enhances cytotoxicity of chemotherapeutics in all ovarian cancer cells as compared to chemotherapy alone.

CONCLUSIONS

Our data indicates the potential of the addition of DNP to the arsenal of drugs available to treat ovarian cancer, whether alone or in combination with chemotherapies. The synergistic effects of DNP in reducing the required amount of chemotherapy, is critical for the alleviation of harmful side effects.

Is there a link between talcum powder, oxidative stress, and ovarian cancer risk?

INTRODUCTION

The link between talcum powder use and cancer, particularly ovarian cancer, has been a topic of scientific research and legal debate for several years. Studies have suggested a potential association between long-term talcum powder use in the genital area and an increased risk of ovarian cancer.

AREAS COVERED

The following report includes up-to-date evidence to support the potential link between talcum powder use and the risk of developing ovarian cancer. The International Agency for Research on Cancer, which is part of the World Health Organization, classified talc-based body powder as possibly carcinogenic to humans when used in the female genital area. However, other studies have not consistently supported this association, and thus more research is needed to establish a clear and definitive link between talcum powder use and cancer. Despite this, recent molecular-level data have linked talc to alterations in redox balance, gene mutations, and inflammatory responses. Specifically, we have identified a role for talc to induce the pro-oxidant state, inhibit apoptosis, and more importantly induced cellular transformation in normal ovarian cells.

EXPERT OPINION

We presented unequivocal evidence to support our opinion that talc is not biologically inert and induces molecular changes that mimic the hallmarks of cancer.

Tumor-targeted delivery of lnc antisense RNA against RCAS1 by live-attenuated tryptophan-auxotrophic Salmonella inhibited 4T1 breast tumors and metastasis in mice

Emerging chemo- and radiotherapy resistance exacerbated the cancer risk and necessitated novel treatment strategies. Although RNA therapeutics against pro-oncogenic genes are highly effective, tumor-specific delivery remains a barrier to the implementation of this valuable tool. In this study, we report a tryptophan-auxotrophic Salmonella typhimurium strain as an onco-therapeutic delivery system with tumor-targeting ability using 4T1 mice breast-cancer model. The receptor-binding cancer antigen expressed on SiSo cell (RCAS1) is a cancer-specific protein that induces the apoptosis of peripheral lymphocytes and confers tumor immune evasion. We designed a long non-coding antisense-RNA against RCAS1 (asRCAS1) and delivered by Salmonella using a non-antibiotic, auxotrophic-selective, eukaryotic expression plasmid, pJHL204. After in vivo tumor-to-tumor passaging, the JOL2888 (ΔtrpA, ΔtrpE, Δasd + asRCAS1) strain exhibited high sustainability in tumors, but did not last in healthy organs, thereby demonstrating tumor specificity and safety. RCAS1 inhibition in the tumor was confirmed by western blotting and qPCR. In mice, JOL2888 treatment reduced tumor-associated macrophages, improved the T cell population, elicited cell-mediated immunity, and suppressed cancer-promoting genes. Consequently, the JOL2888 treatment significantly decreased the tumor volume by 80%, decreased splenomegaly by 30%, and completely arrested lung metastasis. These findings highlight the intrinsic tumor-targeting ability of tryptophan-auxotrophic Salmonella for delivering onco-therapeutic macromolecules.

Gasotransmitters in the tumor microenvironment: Impacts on cancer chemotherapy (Review)

Nitric oxide, carbon monoxide and hydrogen sulfide are three endogenous gasotransmitters that serve a role in regulating normal and pathological cellular activities. They can stimulate or inhibit cancer cell proliferation and invasion, as well as interfere with cancer cell responses to drug treatments. Understanding the molecular pathways governing the interactions between these gases and the tumor microenvironment can be utilized for the identification of a novel technique to disrupt cancer cell interactions and may contribute to the conception of effective and safe cancer therapy strategies. The present review discusses the effects of these gases in modulating the action of chemotherapies, as well as prospective pharmacological and therapeutic interfering approaches. A deeper knowledge of the mechanisms that underpin the cellular and pharmacological effects, as well as interactions, of each of the three gases could pave the way for therapeutic treatments and translational research.

The Breast Cancer Protooncogenes HER2, BRCA1 and BRCA2 and Their Regulation by the iNOS/NOS2 Axis

The expression of inducible nitric oxide synthase (iNOS; NOS2) and derived NO in various cancers was reported to exert pro- and anti-tumorigenic effects depending on the levels of expression and the tumor types. In humans, the breast cancer level of iNOS was reported to be overexpressed, to exhibit pro-tumorigenic activities, and to be of prognostic significance. Likewise, the expression of the oncogenes HER2, BRCA1, and BRCA2 has been associated with malignancy. The interrelationship between the expression of these protooncogenes and oncogenes and the expression of iNOS is not clear. We have hypothesized that there exist cross-talk signaling pathways between the breast cancer protooncogenes, the iNOS axis, and iNOS-mediated NO mutations of these protooncogenes into oncogenes. We review the molecular regulation of the expression of the protooncogenes in breast cancer and their interrelationships with iNOS expression and activities. In addition, we discuss the roles of iNOS, HER2, BRCA1/2, and NO metabolism in the pathophysiology of cancer stem cells. Bioinformatic analyses have been performed and have found suggested molecular alterations responsible for breast cancer aggressiveness. These include the association of BRCA1/2 mutations and HER2 amplifications with the dysregulation of the NOS pathway. We propose that future studies should be undertaken to investigate the regulatory mechanisms underlying the expression of iNOS and various breast cancer oncogenes, with the aim of identifying new therapeutic targets for the treatment of breast cancers that are refractory to current treatments.

Beta-glucans is a potential inhibitor of ovarian cancer: based on molecular and biological aspects

Ovarian cancer is a lethal type of cancer which is initiated in the ovaries and affects 1 out of every 75 women. Due to the high number of deaths (almost 152,000) related to this cancer, it seems that novel effiecient therapeutic methods are required in this field. Beta-glucans are a type of glucose linear polymers which have proven to have a lot of advantageous activities. Recently, investigations have declared that these polysaccharides have the potential to be used as anti-cancer drugs. These agents are able to affect several mechanisms such as inflammation and apoptosis and that is how cancers are prone to be affected by them. In this review, we attempt to investigate the role of beta-glucans on ovarian cancer. We hope that this paper might give novel insights in the field of ovarian cancer treatment.

The Dual Role of STAT1 in Ovarian Cancer: Insight Into Molecular Mechanisms and Application Potentials

The signal transducer and activator of transcription 1 (STAT1) is a transducer protein and acts as a transcription factor but its role in ovarian cancer (OC) is not completely understood. Practically, there are two-faced effects of STAT1 on tumorigenesis in different kinds of cancers. Existing evidence reveals that STAT1 has both tumor-suppressing and tumor-promoting functions involved in angiogenesis, cell proliferation, migration, invasion, apoptosis, drug resistance, stemness, and immune responses mainly through interacting and regulating target genes at multiple levels. The canonical STAT1 signaling pathway shows that STAT1 is phosphorylated and activated by the receptor-activated kinases such as Janus kinase in response to interferon stimulation. The STAT1 signaling can also be crosstalk with other signaling such as transforming growth factor-β signaling involved in cancer cell behavior. OC is often diagnosed at an advanced stage due to symptomless or atypical symptoms and the lack of effective detection at an early stage. Furthermore, patients with OC often develop chemoresistance and recurrence. This review focuses on the multi-faced role of STAT1 and highlights the molecular mechanisms and biological functions of STAT1 in OC.

Variances in the Level of COX-2 and iNOS in Different Grades of Endometrial Cancer

BACKGROUND

Many experimental studies have demonstrated the importance of COX-2 in the tumor angiogenesis. Inducible iNOS is responsible for a high and stable level of nitric oxide and is expressed in response to pro-inflammatory factors.

OBJECTIVE

The aim of this study was to evaluate the expression of COX-2 and iNOS at the protein level and to assess their potential prognostic significance in patients with endometrial cancer.

METHODS

The study group consisted of 45 women with endometrial cancer divided according to the degree of histological differentiation i.e. G1, 17; G2, 15; G3, 13. The control group consisted of 15 women without neoplastic changes. The expression of studied proteins was determined immunohistochemically with specific polyclonal antibodies.

RESULTS

Analysis of the COX-2 expression showed that the optical density of the reaction product in G1 reached 186% in the control group, while the values in G2 and G3 reached 243% and 293%, respectively. In the case of iNOS, the optical density of the reaction product reached the following percentages in the control group: 147% in G1, 243% in G2, and 241% in G3.

CONCLUSION

Our findings suggest that changes in the expression of COX-2 and iNOS may be potentially useful in predicting the progression of endometrial cancer and treatment effectiveness.

Quercetin: a natural compound for ovarian cancer treatment

Ovarian cancer is the main cause of death among all reproductive cancers in females. In 2018, ovarian cancer was the seventh most common cancer of women entire the world. A wide variety of molecular and genetic alterations as well as different response to therapies in the different types of ovarian cancer lead to problems in design a common therapeutic strategy. Besides, ovarian cancer cells have tendency to acquire resistance to common cancer treatments through multiple mechanisms. Various factors, including cytokines, growth factors, proteases, adhesion molecules, coagulation factors, hormones and apoptotic agents have been examined to find effective cancer treatment. Phytochemicals have been indicated to have great potential anti-cancer properties against various types of cancers. Quercetin is one of the phytochemicals that exists extensively in daily foods. Wide evidences revealed that quercetin is able to inhibit various types of cancers including breast, lung, nasopharyngeal, kidney, colorectal, prostate, pancreatic, and ovarian cancer. Several in vitro and in vivo studied conducted to evaluate cytotoxic effects of quercetin on ovarian cancer. Since quercetin does not harm healthy cells and it is cytotoxic to cancer cells via various mechanisms, researchers suggest that it could be an ideal agent for ovarian cancer treatment or an adjuvant agent in combination with other anti-cancer drugs. Thus, in this review, we focused on chemo-preventive and curative attitude of quercetin for ovarian cancer and summarize some of the most recent findings which regard the possible molecular mechanisms by which this natural compound inhibits this cancer.

The Potential Role of iNOS in Ovarian Cancer Progression and Chemoresistance

Inducible nitric oxide synthase (iNOS), the enzyme responsible for nitric oxide (NO) production, is not present in most cells under normal conditions. The expression of its mRNA, as well as its protein synthesis and full enzymatic activity, undergoes multilevel regulation including transcriptional and posttranscriptional mechanisms, the availability of iNOS substrate and cofactors and oxygen tension. However, in various malignant diseases, such as ovarian cancer, the intracellular mechanisms controlling iNOS are dysregulated, resulting in the permanent induction of iNOS expression and activation. The present review summarizes the multistaged processes occurring in normal cells that promote NO synthesis and focuses on factors regulating iNOS expression in ovarian cancer. The possible involvement of iNOS in the chemoresistance of ovarian cancer and its potential as a prognostic/predictive factor in the course of disease development are also reviewed. According to the available yet limited data, it is difficult to draw unequivocal conclusions on the pros and cons of iNOS in ovarian cancer. Most clinical data support the hypothesis that high levels of iNOS expression in ovarian tumors are associated with a greater risk of disease relapse and patient death. However, in vitro studies with various ovarian cancer cell lines indicate a correlation between a high level of iNOS expression and sensitivity to cisplatin.

Effects of eNOS gene polymorphisms on individual susceptibility to cancer: A meta-analysis

BACKGROUND

Whether endothelial nitric oxide synthase (eNOS) polymorphisms are implicated in cancer development remains controversial. Therefore, we performed this study to obtain a more conclusive result on associations between eNOS polymorphisms and cancer.

METHODS

Literature retrieve was conducted in PubMed, Medline and Embase. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated.

RESULTS

Forty-one studies were enrolled for analyses. Pooled overall analyses showed that rs1799983 (dominant model: p = 0.01; recessive model: p = 0.007; allele model: p = 0.005), rs2070744 (recessive model: p = 0.004) and rs869109213 (recessive model: p < 0.0001; allele model: p = 0.02) polymorphisms were all significantly associated with individual susceptibility to cancer. Further subgroup analyses revealed that rs2070744 and rs869109213 polymorphisms were only significantly associated with individual susceptibility to cancer in Caucasians, whereas the rs1799983 polymorphism was significantly associated with individual susceptibility to cancer in both Caucasians and Asians.

CONCLUSIONS

Our findings indicated that rs1799983, rs2070744 and rs869109213 polymorphisms may serve as genetic biomarkers of cancer in certain ethnicities.

Pharmacological Inhibition of NOS Activates ASK1/JNK Pathway Augmenting Docetaxel-Mediated Apoptosis in Triple-Negative Breast Cancer

Purpose: Chemoresistance in triple-negative breast cancer (TNBC) is associated with the activation of a survival mechanism orchestrated by the endoplasmic reticulum (EnR) stress response and by inducible nitric oxide synthase (iNOS). Our aim was to determine the effects of pharmacologic NOS inhibition on TNBC.Experimental Design: TNBC cell lines, SUM-159PT, MDA-MB-436, and MDA-MB-468, were treated with docetaxel and NOS inhibitor (L-NMMA) for 24, 48, and 72 hours. Apoptosis was assessed by flow cytometry using Annexin-V and propidium iodide. Western blot was used to assess ER stress and apoptosis, and rtPCR was used to evaluate s-XBP1. TNBC patient-derived xenografts (PDX) were treated either with vehicle, docetaxel, or combination therapy (NOS inhibition + docetaxel). Mouse weight and tumor volumes were recorded twice weekly. Docetaxel concentration was determined using mass spectrometry. To quantify proliferation and apoptosis, PDX tumor samples were stained using Ki67 and TUNEL assay.Results:In vitro, L-NMMA ameliorated the iNOS upregulation associated with docetaxel. Apoptosis increased when TNBC cells were treated with combination therapy. In TNBC PDXs, combination therapy significantly reduced tumor volume growth and increased survival proportions. In the BCM-5998 PDX model, intratumoral docetaxel concentration was higher in mice receiving combination therapy. Coupling docetaxel with NOS inhibition increased EnR-stress response via coactivation of ATF4 and CHOP, which triggered the pASK1/JNK proapoptotic pathway, promoting cleavage of caspases 3 and 9.Conclusions: iNOS is a critical target for docetaxel resistance in TNBC. Pharmacologic inhibition of NOS enhanced chemotherapy response in TNBC PDX models. Combination therapy may improve prognosis and prevent relapse in TNBC patients who have failed conventional chemotherapy. Clin Cancer Res; 24(5); 1152-62. ©2018 AACR.

Enzymes involved in tumor-driven angiogenesis: A valuable target for anticancer therapy

Angiogenesis plays a pivotal role in cancer progression and is required for tissue invasion and metastasis. Starting with Folkman's initial observations in 1971, basic research continued to shed new molecular insight into this multifaceted process, leading to the development of several anti-angiogenic drugs. To date, anti-vascular endothelial growth factor monoclonal antibodies, such as bevacizumab and ramucirumab, and receptor tyrosine kinase inhibitors (e.g., sorafenib, sunitinib, regorafenib and axitinib) have had a profound impact on the way we treat patients with advanced cancer, providing in some cases unprecedented clinical benefit. The molecular mechanisms underlying tumor-driven angiogenesis have been explored extensively and have unveiled a number of potential clinically relevant targets, including several novel enzymes. In this review, we summarized the current strategies to target tumor-driven angiogenesis through the inhibition of relevant and selected classes of enzymes involved in this process.

Inflammation and Nitrosative Stress Effects in Ovarian and Prostate Pathology and Carcinogenesis

SIGNIFICANCE

Prostate and ovarian cancers are major contributors to cancer-related deaths worldwide. Recently, inflammation and nitrosative stress have been implicated in carcinogenesis, with the overexpression of NOS2 and concomitant release of nitric oxide (NO) associated with cancer initiation and progression. Recent Advances: An increasing body of evidence indicates an association between NOS2 expression and aggressive ovarian cancer. Research also indicates a role for NO in prostate disease pathology and prostate cancer. A therapeutic role for NOS2 inhibition and/or NO drugs exists for the treatment of both ovarian and prostate tumors.

CRITICAL ISSUES

Herein, we review the key molecular effects associated with NOS2 in ovarian and prostate cancer. NOS2 increases angiogenesis and tumor proliferation and correlates with aggressive type II ovarian tumors. NOS2 expressing tumors are sensitive to cisplatin chemotherapy, and NO may be used to sensitize cisplatin-resistant tumors to chemotherapy. NOS2 is highly expressed in prostate tumors compared to non-neoplastic prostate pathologies. NO may play a role in the development of androgen-independent prostate cancer via s-nitrosylation of the androgen receptor. Moreover, NOS2 inhibitors and NO donor drugs show therapeutic potential in ovarian and prostate cancer as single agents or dual drugs, by either inhibiting the effects of NOS2 or increasing NO levels to induce cytotoxic effects.

FUTURE DIRECTIONS

NOS2 and NO present new targets for the treatment of ovarian and prostate tumors. Furthermore, understanding NO-related tumor biology in these cancers presents a new means for improved patient stratification to the appropriate treatment regimen. Antioxid. Redox Signal. 26, 1078-1090.

Reduction-oxidation pathways involved in cancer development: a systematic review of literature reviews

Oxidative stress results from an imbalance of the reactive oxygen species/reactive nitrogen species (ROS/RNS) production and the oxidants defense system. Extensive research during the last decades has revealed that oxidative stress can mediate cancer initiation and development by leading not only to molecular damage but also to a disruption of reduction-oxidation (redox) signaling. In order to provide a global overview of the redox signaling pathways, which play a role in cancer formation, we conducted a systematic literature search in PubMed and ISI Web of Science and identified 185 relevant reviews published in the last 10 years. The 20 most frequently described pathways were selected to be presented in this systematic review and could be categorized into 3 groups: Intracellular ROS/RNS generating organelles and enzymes, signal transduction cascades kinases/phosphatases and transcription factors. Intracellular ROS/RNS generation organelles are mitochondria, endoplasmic reticulum and peroxisomes. Enzymes, including NOX, COX, LOX and NOS, are the most prominent enzymes generating ROS/RNS. ROS/RNS act as redox messengers of transmembrane receptors and trigger the activation or inhibition of signal transduction kinases/phosphatases, such as the family members of protein tyrosine kinases and protein tyrosine phosphatases. Furthermore, these reactions activate downstream signaling pathways including protein kinase of the MAPK cascade, PI3K and PKC. The kinases and phosphatases regulate the phosphorylation status of transcription factors including APE1/Ref-1, HIF-1α, AP-1, Nrf2, NF-κB, p53, FOXO, STAT, and β-catenin. Finally, we briefly discuss cancer prevention and treatment opportunities, which address redox pathways and further research needs.

Updates of the role of oxidative stress in the pathogenesis of ovarian cancer

Clinical and epidemiological investigations have provided evidence supporting the role of reactive oxygen species (ROS) and reactive nitrogen species (RNS), collectively known as oxidative stress, in the etiology of cancer. Exogenous factors such as chronic inflammation, infection and hypoxia are major sources of cellular oxidative stress. Specifically, oxidative stress plays an important role in the pathogenesis, neoangiogenesis, and dissemination of local or distant ovarian cancer, as it is known to induce phenotypic modifications of tumor cells by cross talk between tumor cells and the surrounding stroma. Subsequently, the biological significance of the relationship between oxidative stress markers and various stages of epithelial ovarian cancer highlights potential therapeutic interventions as well as provides urgently needed early detection biomarkers. In the light of our scientific research and the most recent experimental and clinical observations, this review provides the reader with up to date most relevant findings on the role of oxidative stress in the pathogenesis of ovarian cancer and the possible therapeutic implications.

Specific point mutations in key redox enzymes are associated with chemoresistance in epithelial ovarian cancer

Oxidative stress plays an important role in the pathophysiology of ovarian cancer. Resistance to chemotherapy presents a significant challenge for ovarian cancer treatment. Specific single nucleotide polymorphisms (SNPs) in key redox enzymes have been associated with ovarian cancer survival and progression. The objective of this study was to determine whether chemotherapy induces point mutations in key redox enzymes that lead to the acquisition of chemoresistance in epithelial ovarian cancer (EOC). Human EOC cell lines and their chemoresistant counterpart were utilized for this study. Specific SNPs in key redox enzymes were analyzed by TaqMan SNP Genotyping. Activities and levels of key redox enzymes were determined by real-time RT-PCR, ELISA and a greiss assay. Point mutations in key redox enzymes were introduced into sensitive EOC cells via the CRISPR/Cas9 system. Cell viability and IC₅₀ for cisplatin were determined by the MTT Cell Proliferation Assay. Data was analyzed with SPSS using Student's two-tailed t-tests and One-way ANOVA followed by Dunnett's or Tukey's post hoc tests, p<0.05. Here, we demonstrate that chemoresistant EOC cells are characterized by a further enhancement in oxidative stress as compared to sensitive counterparts. Additionally, chemoresistant EOC cells manifested specific point mutations, which are associated with altered enzymatic activity, in key redox enzymes that are not detected in sensitive counterparts. Supplementation of an antioxidant was able to successfully sensitize EOC cells to chemotherapeutics. Causality was established by the induction of these point mutations in sensitive EOC cells, which resulted in a significant increase in the level of chemoresistance. These findings indicate that chemotherapy induces specific point mutations in key redox enzymes that contribute to the acquisition of chemoresistance in EOC cells, highlighting a potential novel mechanism. Identification of targets for chemoresistance with either biomarker and/or screening potential will have a significant impact for the treatment of this disease.

The Role of Angiogenesis in the Persistence of Chemoresistance in Epithelial Ovarian Cancer

OBJECTIVE

Chemoresistance remains a major challenge in the treatment of ovarian cancer. As part of a survival mechanism, tumor cells have been shown to release proangiogenic factors, such as vascular endothelial growth factor (VEGF), through a mechanism that involves the upregulation of hypoxia-induced factor (HIF)-1α. The objective of this study was to compare the expression of VEGF and its receptors (R1 and R2) as well as HIF-1α in chemoresistant epithelial ovarian cancer (EOC) cells to their chemosensitive counterparts and determine their impact on angiogenesis.

METHODS

Two human EOC cell lines, MDAH-2774 and SKOV-3, and their cisplatin- or taxotere-resistant counterparts were used. Total RNA and protein were subjected to real-time reverse transcriptase-polymerase chain reaction, immunoprecipitation/Western blot and enzyme-linked immunosorbent assay to evaluate the expression of VEGF, VEGF receptors (R1 and R2), and HIF-1α. Angiogenesis was assessed with an in vitro angiogenesis assay. Data were analyzed using independent Student t tests and chi-square.

RESULTS

Both taxotere- and cisplatin-resistant MDAH-2774 and SKOV-3 EOC cell lines manifested a significant decrease in VEGF, VEGF receptors, HIF-1α messenger RNA, and protein levels as compared to their chemosensitive counterparts. There was a significant decrease in the number and thickness of polygon blood vessel formation in chemoresistant EOC cells compared to chemosensitive counterparts.

CONCLUSION

Cisplatin- and taxotere-resistant EOC cells are characterized by lower VEGF, VEGF receptors, and HIF-1α, and decreased angiogenesis. These findings may indicate a decrease in drug delivery at the tumor site, hence allowing the persistence of chemoresistant EOC cells.

A Single Nucleotide Polymorphism in Catalase Is Strongly Associated with Ovarian Cancer Survival

Ovarian cancer is the deadliest of all gynecologic cancers. Recent evidence demonstrates an association between enzymatic activity altering single nucleotide polymorphisms (SNP) with human cancer susceptibility. We sought to evaluate the association of SNPs in key oxidant and antioxidant enzymes with increased risk and survival in epithelial ovarian cancer. Individuals (n = 143) recruited were divided into controls, (n = 94): healthy volunteers, (n = 18), high-risk BRCA1/2 negative (n = 53), high-risk BRCA1/2 positive (n = 23) and ovarian cancer cases (n = 49). DNA was subjected to TaqMan SNP genotype analysis for selected oxidant and antioxidant enzymes. Of the seven selected SNP studied, no association with ovarian cancer risk (Pearson Chi-square) was found. However, a catalase SNP was identified as a predictor of ovarian cancer survival by the Cox regression model. The presence of this SNP was associated with a higher likelihood of death (hazard ratio (HR) of 3.68 (95% confidence interval (CI): 1.149–11.836)) for ovarian cancer patients. Kaplan-Meier survival analysis demonstrated a significant median overall survival difference (108 versus 60 months, p<0.05) for those without the catalase SNP as compared to those with the SNP. Additionally, age at diagnosis greater than the median was found to be a significant predictor of death (HR of 2.78 (95% CI: 1.022–7.578)). This study indicates a strong association with the catalase SNP and survival of ovarian cancer patients, and thus may serve as a prognosticator.

iNOS Activity Modulates Inflammation, Angiogenesis, and Tissue Fibrosis in Polyether-Polyurethane Synthetic Implants

There is considerable interest in implantation techniques and scaffolds for tissue engineering and, for safety and biocompatibility reasons, inflammation, angiogenesis, and fibrosis need to be determined. The contribution of inducible nitric oxide synthase (iNOS) in the regulation of the foreign body reaction induced by subcutaneous implantation of a synthetic matrix was never investigated. Here, we examined the role of iNOS in angiogenesis, inflammation, and collagen deposition induced by polyether-polyurethane synthetic implants, using mice with targeted disruption of the iNOS gene (iNOS^−/−) and wild-type (WT) mice. The hemoglobin content and number of vessels were decreased in the implants of iNOS^−/− mice compared to WT mice 14 days after implantation. VEGF levels were also reduced in the implants of iNOS^−/− mice. In contrast, the iNOS^−/− implants exhibited an increased neutrophil and macrophage infiltration. However, no alterations were observed in levels of CXCL1 and CCL2, chemokines related to neutrophil and macrophage migration, respectively. Furthermore, the implants of iNOS^−/− mice showed boosted collagen deposition. These data suggest that iNOS activity controls inflammation, angiogenesis, and fibrogenesis in polyether-polyurethane synthetic implants and that lack of iNOS expression increases foreign body reaction to implants in mice.

[Arginase and NO-synthase pathways of L-arginine metabolism in peripheral blood lymphocytes of patients with ovarian cancer]

The peculiarities ofarginase and NO-synthase pathways of L-arginine metabolism in peripheral blood lymphocytes of patients with ovarian cancer were studied. It was shown that the development of cancer pathology is associated with an imbalance in the NO synthesis in blood lymphocytes. The reason for such imbalance is the activation of arginase and inducible isoform of NO-synthase (iNOS) and significant inhibition of its constitutive isoform. The analysis of the kinetic properties of NOS of blood lymphocytes of patients with ovarian cancer was carried out. It was shown that the affinity constant of iNOS affinity for L-arginine is 5.4-fold lower than for eNOS of blood lymphocytes of persons in the control group. The inhibition of eNOS occurs via non-competitive type and is related to the reduction of maximum reaction rate.

The role of oxidative stress in the development of cisplatin resistance in epithelial ovarian cancer

OBJECTIVE

To investigate the role of oxidative stress in the development of cisplatin resistance in epithelial ovarian cancer (EOC).

METHODS

Two parent EOC cell lines (MDAH-2774 and SKOV-3) and their chemoresistant counterparts (cisplatin, 50 µmol/L) were used. Total RNA was extracted and subjected to real-time reverse transcriptase polymerase chain reaction to evaluate the expression of glutathione reductase (GSR) and inducible nitric oxide synthase (iNOS), as well as nitrate/nitrite levels. Analysis of variance was used for main effects and Tukey for post hoc analysis at P < .05 for statistical significance.

RESULTS

Both cisplatin resistant cell lines displayed a significant decrease in GSR messenger RNA (mRNA) levels and activity (P < .01). As compared to sensitive controls, nitrate/nitrite levels were significantly higher in SKOV-3 cisplatin resistant cells while iNOS mRNA levels were significantly higher in MDAH-2774 cisplatin resistant cells (P < .05).

CONCLUSION

Our data suggest that the development of cisplatin resistance tilts the balance toward a pro-oxidant state in EOC.

Targeted inhibition of inducible nitric oxide synthase inhibits growth of human melanoma in vivo and synergizes with chemotherapy

PURPOSE

Aberrant expression of inflammatory molecules, such as inducible nitric oxide (NO) synthase (iNOS), has been linked to cancer, suggesting that their inhibition is a rational therapeutic approach. Whereas iNOS expression in melanoma and other cancers is associated with poor clinical prognosis, in vitro and in vivo studies suggest that iNOS and NO can have both protumor and antitumor effects. We tested the hypothesis that targeted iNOS inhibition would interfere with human melanoma growth and survival in vivo in a preclinical model.

EXPERIMENTAL DESIGN

We used an immunodeficient non-obese diabetic/severe combined immunodeficient xenograft model to test the susceptibility of two different human melanoma lines to the orally-given iNOS-selective small molecule antagonist N(6)-(1-iminoethyl)-l-lysine-dihydrochloride (L-nil) with and without cytotoxic cisplatin chemotherapy.

RESULTS

L-nil significantly inhibited melanoma growth and extended the survival of tumor-bearing mice. L-nil treatment decreased the density of CD31+ microvessels and increased the number of apoptotic cells in tumor xenografts. Proteomic analysis of melanoma xenografts with reverse-phase protein array identified alterations in the expression of multiple cell signaling and survival genes after L-nil treatment. The canonical antiapoptotic protein Bcl-2 was downregulated in vivo and in vitro after L-nil treatment, which was associated with increased susceptibility to cisplatin-mediated tumor death. Consistent with this observation, combination therapy with L-nil plus cisplatin in vivo was more effective than either drug alone, without increased toxicity.

CONCLUSIONS

These data support the hypothesis that iNOS and iNOS-derived NO support tumor growth in vivo and provide convincing preclinical validation of targeted iNOS inhibition as therapy for solid tumors.

Reduction of hypoxia-induced angiogenesis in ovarian cancer cells by inhibition of HIF-1 alpha gene expression

PURPOSE

The goal of this study was to investigate the effects of silencing HIF-1 alpha gene expression with specific small interfering RNA (siRNA) on VEGF production and angiogenesis in epithelial ovarian cancer (EOC) cells.

METHODS

Two EOC cell lines, MDAH-2774 and SKOV-3, were cultured under normoxic (20% O(2)) and hypoxic (2% O(2)) conditions using standard techniques. After EOC cells were transfected with siRNA, HIF-1 alpha and VEGF mRNA levels were measured by real-time RT-PCR. Angiogenesis was evaluated utilizing an in vitro assay model consisting of human umbilical vein endothelial cells (HUVEC) and polymerized ECM Matrix.

RESULTS

Both EOC cell lines evaluated constitutively expressed HIF-1 alpha and VEGF mRNA. HIF-1 alpha and VEGF mRNA levels were significantly increased in response to hypoxia (P < 0.05). Under hypoxic conditions, inhibition of HIF-1 alpha gene expression by a specific siRNA resulted in a significant reduction in HIF-1 alpha and VEGF mRNA levels (P < 0.05). In the in vitro angiogenesis model, supernatant from the hypoxic EOC cells induced the HUVEC to form a complex tubular network, a hallmark of angiogenesis. Semi-quantitative analysis of the angiogenesis assay revealed a significant reduction in tube formation when supernatant from HIF-1 alpha siRNA-treated hypoxic EOC cell was used (P < 0.05).

CONCLUSION

Inhibition of HIF-1 alpha expression by specific siRNA resulted in a significant decrease in VEGF production and angiogenesis. Further investigation of HIF-1 alpha inhibition for anti-tumor activity is warranted and may potentially prove HIF-1 alpha as a therapeutic target in the management ovarian cancer.

Myeloperoxidase serves as a redox switch that regulates apoptosis in epithelial ovarian cancer

OBJECTIVES

Resistance to apoptosis is a key feature of cancer cells and is believed to be regulated by nitrosonium ion (NO(+))-induced S-nitrosylation of key enzymes. Nitric oxide (NO), produced by inducible nitric oxide synthase (iNOS), is utilized by MPO to generated NO(+). We sought to investigate the expression of myeloperoxidase (MPO) and iNOS in epithelial ovarian cancer (EOC) and determine their effect on S-nitrosylation of caspase-3 and its activity as well as apoptosis.

METHODS

MPO and iNOS expression were determined using immunofluorescence in SKOV-3 and MDAH-2774 and EOC tissue sections. S-nitrosylation of caspase-3 and its activity, levels of MPO and iNOS, as well as apoptosis, were evaluated in the EOC cells before and after silencing MPO or iNOS genes with specific siRNA probes utilizing real-time RT-PCR, ELISA, and TUNEL assays.

RESULTS

MPO and iNOS are expressed in EOC cell lines and in over 60% of invasive EOC cases with no expression in normal ovarian epithelium. Indeed, silencing of MPO or iNOS gene expression resulted in decreased S-nitrosylation of caspase-3, increased caspase-3 activity, and increased apoptosis but with a more significant effect when silencing MPO.

CONCLUSION

MPO and iNOS are colocalized to the same cells in EOC but not in the normal ovarian epithelium. Silencing of either MPO or iNOS significantly induced apoptosis, highlighting their role as a redox switch that regulates apoptosis in EOC. Understanding the mechanisms by which MPO functions as a redox switch in regulating apoptosis in EOC may lead to future diagnostic tools and therapeutic interventions.

Production of nitric oxide and expression of inducible nitric oxide synthase in ovarian cystic tumors

Tumor sections from nonneoplastic (n = 15), benign (n = 28), and malignant ovarian tumors (n = 20) were obtained from 63 women. Immunohistochemistry of the tumor sections demonstrated that inducible nitric oxide synthase (iNOS) expression was increased in ovarian cancer samples compared to nonneoplastic or benign tumor samples. Using the Griess method, nitric oxide (NO) metabolite levels were also found to be elevated in malignant tumor samples compared to benign tumor samples (P < .05). For stage I ovarian cancer, intracystic NO levels >80 μM were more frequent than NO levels <80 μM, and iNOS expression in well-differentiated carcinomas was greater than in moderately/poorly differentiated carcinomas (P < .05). These data suggest an important role for NO in ovarian carcinogenesis.