Soluble Guanylate Cyclase ß1 Subunit Represses Human Glioblastoma Growth.

Malignant glioma is the most common and deadly brain tumor. A marked reduction in the levels of sGC (soluble guanylyl cyclase) transcript in the human glioma specimens has been revealed in our previous studies. In the present study, restoring the expression of sGCß1 alone repressed the aggressive course of glioma. The antitumor effect of sGCß1 was not associated with enzymatic activity of sGC since overexpression of sGCß1 alone did not influence the level of cyclic GMP. Additionally, sGCß1-induced inhibition of the growth of glioma cells was not influenced by treatment with sGC stimulators or inhibitors. The present study is the first to reveal that sGCß1 migrated into the nucleus and interacted with the promoter of the TP53 gene. Transcriptional responses induced by sGCß1 caused the G0 cell cycle arrest of glioblastoma cells and inhibition of tumor aggressiveness. sGCß1 overexpression impacted signaling in glioblastoma multiforme, including the promotion of nuclear accumulation of p53, a marked reduction in CDK6, and a significant decrease in integrin α6. These anticancer targets of sGCß1 may represent clinically important regulatory pathways that contribute to the development of a therapeutic strategy for cancer treatment.

Nitric oxide-releasing gel accelerates healing in a diabetic murine splinted excisional wound model.

Introduction: According to the American Diabetes Association (ADA), 9-12 million patients suffer from chronic ulceration each year, costing the healthcare system over USD $25 billion annually. There is a significant unmet need for new and efficacious therapies to accelerate closure of non-healing wounds. Nitric Oxide (NO) levels typically increase rapidly after skin injury in the inflammatory phase and gradually diminish as wound healing progresses. The effect of increased NO concentration on promoting re-epithelization and wound closure has yet to be described in the context of diabetic wound healing. Methods: In this study, we investigated the effects of local administration of an NO-releasing gel on excisional wound healing in diabetic mice. The excisional wounds of each mouse received either NO-releasing gel or a control phosphate-buffered saline (PBS)-releasing gel treatment twice daily until complete wound closure. Results: Topical administration of NO-gel significantly accelerated the rate of wound healing as compared with PBS-gel-treated mice during the later stages of healing. The treatment also promoted a more regenerative ECM architecture resulting in shorter, less dense, and more randomly aligned collagen fibers within the healed scars, similar to that of unwounded skin. Wound healing promoting factors fibronectin, TGF-ß1, CD31, and VEGF were significantly elevated in NO vs. PBS-gel-treated wounds. Discussion: The results of this work may have important clinical implications for the management of patients with non-healing wounds.

John Mendelsohn: A visionary scientist, oncologist and leader.

Dr. John Mendelsohn is credited for the concept of targeting the epidermal growth factor receptor (EGFR), providing the first evidence of anticancer activity of antagonist anti-EGFR mAb, and developing the Erbitux (Cetuximab) drug for cancer patients. During his professional journey, Dr. Mendelsohn also helped to build and elevate the status of three cancer cancers, all while touching the lives of cancer patients around the globe. He was a towering figure, and his passing in January 2019 casts a very long shadow over the entire field of cancer research and treatment. Although no one person can ever adequately fill John Mendelsohn's very large shoes, we can all learn by his remarkable example. Here we discuss Dr. Mendelsohn's professional life to spotlight his influence on oncology and also share personal reflections from us and several colleagues: Tony Hunter, Robert A. Weinberg, Robert C. Bast, Raymond Sawaya, David M. Gershenson, Christopher J Logothetis, Stanley R. Hamilton, Mien-Chie Hung, and George M. Stancel. See related article Kumar et al. Can Res 2019; 79:4315-4323.

Differentiation of Human Induced Pluripotent or Embryonic Stem Cells Decreases the DNA Damage Repair by Homologous Recombination.

The nitric oxide (NO)-cyclic GMP pathway contributes to human stem cell differentiation, but NO free radical production can also damage DNA, necessitating a robust DNA damage response (DDR) to ensure cell survival. How the DDR is affected by differentiation is unclear. Differentiation of stem cells, either inducible pluripotent or embryonic derived, increased residual DNA damage as determined by γ-H2AX and 53BP1 foci, with increased S-phase-specific chromosomal aberration after exposure to DNA-damaging agents, suggesting reduced homologous recombination (HR) repair as supported by the observation of decreased HR-related repair factor foci formation (RAD51 and BRCA1). Differentiated cells also had relatively increased fork stalling and R-loop formation after DNA replication stress. Treatment with NO donor (NOC-18), which causes stem cell differentiation has no effect on double-strand break (DSB) repair by non-homologous end-joining but reduced DSB repair by HR. Present studies suggest that DNA repair by HR is impaired in differentiated cells.

Tadalafil: Protective Action against the Development of Multiple Organ Failure Syndrome.

INTRODUCTION: Multiple organ failure syndrome (MOFS) is a pathology associated to unspecified and severe trauma, characterized by elevated morbidity and mortality. The complex inflammatory MOFS-related reactions generate important ischemia-reperfusion responses in the induction of this syndrome. Nitric oxide elevation, through the activation of cyclic guanosine monophosphate (cGMP), has the potential of counteracting the typical systemic vasoconstriction, and platelet-induced hypercoagulation. Tadalafil would possibly act protectively by reducing cGMP degradation with consequent diffuse vasodilatation, besides reduction of platelet-induced hypercoagulation, thus, preventing multiple organ failure syndrome development. METHODS: The experimental protocol was previously approved by an institution animal research committee. Experimental MOFS was induced through the stereotaxic micro-neurosurgical bilateral anterior hypothalamic lesions model. Groups of 10 Wistar rats were divided into: a) Non-operated control; b) Operated control group; c) 2 hours after tadalafil-treated operated group; d) 4 hours after tadalafil-treated operated group; e) 8 hours after post-treated operated group. The animals were sacrificed 24 hours after the neurosurgical procedure and submitted to histopathologic examination of five organs: brain, lungs, stomach, kidneys, and liver. RESULTS: The electrolytic hypothalamic lesions resulted in a full picture of MOFS with disseminated multiple-organs lesions, provoked primarily by diffusely spread micro-thrombi. The treatment with tadalafil 2 hours after the micro-neurosurgical lesions reduced the experimental MOFS lesions development, in a highly significant level (P<0.01) of 58.75%. The treatment with tadalafil, 4 hours after the micro-neurosurgically-induced MOFS lesions, also reduced in 49.71%, in a highly significant level (P<0.01). Finally, the treatment with tadalafil 8 hours after the neurosurgical procedure resulted in a statistically significant reduction of 30.50% (P<0.05) of the experimentally-induced MOFS gravity scores. CONCLUSION: The phosphodiesterase 5 inhibitor, tadalafil, in the doses and timing utilized, showed to protect against the experimentally-induced MOFS.

Tadalafil: protective action against the development of multiple organ failure syndrome

Abstract Introduction: Multiple organ failure syndrome (MOFS) is a pathology associated to unspecified and severe trauma, characterized by elevated morbidity and mortality. The complex inflammatory MOFS-related reactions generate important ischemia-reperfusion responses in the induction of this syndrome. Nitric oxide elevation, through the activation of cyclic guanosine monophosphate (cGMP), has the potential of counteracting the typical systemic vasoconstriction, and platelet-induced hypercoagulation. Tadalafil would possibly act protectively by reducing cGMP degradation with consequent diffuse vasodilatation, besides reduction of platelet-induced hypercoagulation, thus, preventing multiple organ failure syndrome development. Methods: The experimental protocol was previously approved by an institution animal research committee. Experimental MOFS was induced through the stereotaxic micro-neurosurgical bilateral anterior hypothalamic lesions model. Groups of 10 Wistar rats were divided into: a) Non-operated control; b) Operated control group; c) 2 hours after tadalafil-treated operated group; d) 4 hours after tadalafil-treated operated group; e) 8 hours after post-treated operated group. The animals were sacrificed 24 hours after the neurosurgical procedure and submitted to histopathologic examination of five organs: brain, lungs, stomach, kidneys, and liver. Results: The electrolytic hypothalamic lesions resulted in a full picture of MOFS with disseminated multiple-organs lesions, provoked primarily by diffusely spread micro-thrombi. The treatment with tadalafil 2 hours after the micro-neurosurgical lesions reduced the experimental MOFS lesions development, in a highly significant level (P<0.01) of 58.75%. The treatment with tadalafil, 4 hours after the micro-neurosurgically-induced MOFS lesions, also reduced in 49.71%, in a highly significant level (P<0.01). Finally, the treatment with tadalafil 8 hours after the neurosurgical procedure resulted in a statistically significant reduction of 30.50% (P<0.05) of the experimentally-induced MOFS gravity scores. Conclusion: The phosphodiesterase 5 inhibitor, tadalafil, in the doses and timing utilized, showed to protect against the experimentally-induced MOFS.

Enhancing cold atmospheric plasma treatment of cancer cells by static magnetic field.

It has been reported since late 1970 that magnetic field interacts strongly with biological systems. Cold atmospheric plasma (CAP) has also been widely studied over the past few decades in physics, biology, and medicine. In this study, we propose a novel idea to combine static magnetic field (SMF) with CAP as a tool for cancer therapy. Breast cancer cells and wild type fibroblasts were cultured in 96-well plates and treated by CAP with or without SMF. Breast cancer cells MDA-MB-231 showed a significant decrease in viability after direct plasma treatment with SMF (compared to only plasma treatment). In addition, cancer cells treated by the CAP-SMF-activated medium (indirect treatment) also showed viability decrease but was slightly weaker than the direct plasma-SMF treatment. By integrating the use of SMF and CAP, we were able to discover their advantages that have yet to be utilized. Bioelectromagnetics. 38:53-62, 2017. © 2016 Wiley Periodicals, Inc.

Epigenetic regulation of soluble guanylate cyclase (sGC) ß1 in breast cancer cells.

Soluble guanylate cyclase (sGC) is a heterodimer composed of α and ß subunits. The loss of sGCß1 has been implicated in several vascular and nonvascular diseases. Our analysis showed that higher levels of sGCß1 in breast cancer tissues are correlated with greater survival probability than lower sGCß1 levels. However, there is no information on sGC regulation by epigenetic mechanisms. We examined the role of histone deacetylase (HDAC) inhibitors in regulating sGCα1 and -ß1 expression in human breast cancer MDA-MB-231 and MDA-MB-468 cell lines. The class I HDAC inhibitors increased the expression of sGCß1 more than sGCα1. Transient overexpression of HDAC3, but not HDAC1 or HDAC2, significantly reduced sGCß1 mRNA. Chromatin immunoprecipitation assay confirmed an enhanced binding of HDAC3 to the sGCß1 proximal promoter, which could be reversed by panobinostat (LBH-589) treatment. Mutations at the CCAAT binding sequence, a major element regulating sGCß1 expression, markedly reduced the efficacy of LBH-589 in augmenting sGCß1 promoter activity. LBH-589 markedly enhanced the binding of nuclear transcription factor Y, subunit α, to the sGCß1 promoter (CCAAT binding sequence). In summary, HDAC3 is an endogenous antagonist of sGCß1 expression. Inhibition of HDAC3 with targeted therapy could benefit treatment of the diseases associated with sGCß1 down-regulation and/or deficiency such as cancer and several vascular-related diseases.-Sotolongo, A., Mónica, F. Z., Kots, A., Xiao, H., Liu, J., Seto, E., Bian, K., Murad, F. Epigenetic regulation of soluble guanylate cyclase (sGC) ß1 in breast cancer cells.

Stabilizing the cold plasma-stimulated medium by regulating medium's composition.

Over past several years, the cold plasma-stimulated medium (PSM) has shown its remarkable anti-cancer capacity in par with the direct cold plasma irradiation on cancer cells or tumor tissues. Independent of the cold plasma device, PSM has noticeable advantage of being a flexible platform in cancer treatment. Currently, the largest disadvantage of PSM is its degradation during the storage over a wide temperature range. So far, to stabilize PSM, it must be remained frozen at -80 °C. In this study, we first reveal that the degradation of PSM is mainly due to the reaction between the reactive species and specific amino acids; mainly cysteine and methionine in medium. Based on this finding, both H2O2 in PSM and the anti-cancer capacity of PSM can be significantly stabilized during the storage at 8 °C and -25 °C for at least 3 days by using phosphate-buffered saline (PBS) and cysteine/methionine-free Dulbecco's Modified Eagle Medium (DMEM). In addition, we demonstrate that adding a tyrosine derivative, 3-Nitro-L-tyrosine, into DMEM can mitigate the degradation of PSM at 8 °C during 3 days of storage. This study provides a solid foundation for the future anti-cancer application of PSM.

Rutaecarpine ameliorates hyperlipidemia and hyperglycemia in fat-fed, streptozotocin-treated rats via regulating the IRS-1/PI3K/Akt and AMPK/ACC2 signaling pathways.

AIM: We have shown that rutaecarpine extracted from the dried fruit of Chinese herb Evodia rutaecarpa (Juss) Benth (Wu Zhu Yu) promotes glucose consumption and anti-inflammatory cytokine expression in insulin-resistant primary skeletal muscle cells. In this study we investigated whether rutaecarpine ameliorated the obesity profiles, lipid abnormality, glucose metabolism and insulin resistance in rat model of hyperlipidemia and hyperglycemia. METHODS: Rats fed on a high-fat diet for 8 weeks, followed by injection of streptozotocin (30 mg/kg, ip) to induce hyperlipidemia and hyperglycemia. One week after streptozotocin injection, the fat-fed, streptozotocin-treated rats were orally treated with rutaecarpine (25 mg·kg(-1)·d(-1)) or a positive control drug metformin (250 mg·kg(-1)·d(-1)) for 7 weeks. The body weight, visceral fat, blood lipid profiles and glucose levels, insulin sensitivity were measured. Serum levels of inflammatory cytokines were analyzed. IRS-1 and Akt/PKB phosphorylation, PI3K and NF-κB protein levels in liver tissues were assessed; pathological changes of livers and pancreases were examined. Glucose uptake and AMPK/ACC2 phosphorylation were studied in cultured rat skeletal muscle cells in vitro. RESULTS: Administration of rutaecarpine or metformin significantly decreased obesity, visceral fat accumulation, water consumption, and serum TC, TG and LDL-cholesterol levels in fat-fed, streptozotocin-treated rats. The two drugs also attenuated hyperglycemia and enhanced insulin sensitivity. Moreover, the two drugs significantly decreased NF-κB protein levels in liver tissues and plasma TNF-α, IL-6, CRP and MCP-1 levels, and ameliorated the pathological changes in livers and pancreases. In addition, the two drugs increased PI3K p85 subunit levels and Akt/PKB phosphorylation, but decreased IRS-1 phosphorylation in liver tissues. Treatment of cultured skeletal muscle cells with rutaecarpine (20-180 µmol/L) or metformin (20 µmol/L) promoted the phosphorylation of AMPK and ACC2, and increased glucose uptake. CONCLUSION: Rutaecarpine ameliorates hyperlipidemia and hyperglycemia in fat-fed, streptozotocin-treated rats via regulating IRS-1/PI3K/Akt signaling pathway in liver and AMPK/ACC2 signaling pathway in skeletal muscles.

Anti-Inflammatory Effect of 1,3,5,7-Tetrahydroxy-8-isoprenylxanthone Isolated from Twigs of Garcinia esculenta on Stimulated Macrophage.

Garcinia Linn. plants having rich natural xanthones and benzophenones with anti-inflammatory activity attracted a great deal of attention to discover and develop them as potential drug candidates. Through screening targeting nitric oxide accumulation in stimulated macrophage, we found that 1,3,5,7-tetrahydroxy-8-isoprenylxanthone (TIE) had potential anti-inflammatory effect. To understand how TIE elicits its anti-inflammatory activity, we uncovered that it significantly inhibits the production of nitric oxide (NO) and prostaglandin E2 (PGE2) in LPS/IFNγ-stimulated RAW264.7 cells. In further study, we showed that TIE reduced the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), two key molecules responsible for the production of NO and PGE2 during inflammation progress. Additionally, TIE also suppressed the expression of inflammatory cytokines IL-6, IL-12, and TNF-α. TIE-led suppression in iNOS, COX-2, and cytokines production were probably the consequence of TIE's capability to block ERK and p38MAPK signaling pathway. Moreover, TIE blocked activation of nuclear factor-kappa B (NF-κB) as well as NF-κB regulation of miR155 expression. Our study suggests that TIE may represent as a potential therapeutic agent for the treatment of inflammatory diseases.

Differential Effects of Cold Atmospheric Plasma in the Treatment of Malignant Glioma.

OBJECTIVE: Cold atmospheric plasma (CAP) has recently been shown to selectively target cancer cells with minimal effects on normal cells. We systematically assessed the effects of CAP in the treatment of glioblastoma. METHODS: Three glioma cell lines, normal astrocytes, and endothelial cell lines were treated with CAP. The effects of CAP were then characterized for viability, cytotoxicity/apoptosis, and cell cycle effects. Statistical significance was determined with student's t-test. RESULTS: CAP treatment decreases viability of glioma cells in a dose dependent manner, with the ID50 between 90-120 seconds for all glioma cell lines. Treatment with CAP for more than 120 seconds resulted in viability less than 35% at 24-hours posttreatment, with a steady decline to less than 20% at 72-hours. In contrast, the effect of CAP on the viability of NHA and HUVEC was minimal, and importantly not significant at 90 to 120 seconds, with up to 85% of the cells remained viable at 72-hours post-treatment. CAP treatment produces both cytotoxic and apoptotic effects with some variability between cell lines. CAP treatment resulted in a G2/M-phase cell cycle pause in all three cell lines. CONCLUSIONS: This preliminary study determined a multi-focal effect of CAP on glioma cells in vitro, which was not observed in the non-tumor cell lines. The decreased viability depended on the treatment duration and cell line, but overall was explained by the induction of cytotoxicity, apoptosis, and G2/M pause. Future studies will aim at further characterization with more complex pre-clinical models.

What is next in nitric oxide research? From cardiovascular system to cancer biology.

The broad role of nitric oxide (NO) and cyclic GMP in biochemistry and biology as important messenger molecules is evident from the numerous publications in this research field. NO and cGMP have been known as components of the key signaling pathway in regulating numerous processes such as vascular dilation, blood pressure, neurotransmission, cardiovascular function, and renal function. In spite of almost 150,000 publications with nitric oxide and cyclic GMP, there are few publications regarding the effects of these messenger molecules on gene regulation, cell differentiation and cell proliferation. Our research data with embryonic stem cells and several cancer cell lines suggest that nitric oxide, its receptor soluble guanylyl cyclase (sGC) and sGC's product cyclic GMP can regulate the processes of proliferation and differentiation. Furthermore, we have found that undifferentiated stem cells and some malignant tumors such as human glioma have decreased levels of sGC and translocation of the sGCß1 subunit to the nucleus. We propose that sGC and cyclic GMP function as tumor suppressors. An understanding of the mechanisms of the translocation of the sGCß1 subunit into the nucleus and the possible regulation of gene expression of NO and/or cyclic CMP could lead to novel and innovative approaches to cancer therapy and stem cell proliferation and differentiation.

sGC-cGMP signaling: target for anticancer therapy.

The biologic endogenous production of cGMP was reported in the 1960s and followed by the demonstration of guanylyl cyclase activity and the isoforms of soluble and membrane-bound guanylyl cyclases. During the same period, cGMP specific phosphodiesterases also was discovered. Murad's lab established link between the endothelium derived relaxation factor (EDRF) and elevated cGMP concentration in the vascular system. October 12, 1998, the Nobel Assembly awarded the Nobel Prize in Medicine or Physiology to scientists Robert Furchgott, Louis Ignarro, and Ferid Murad for their discoveries concerning nitric oxide (NO) as a signaling molecule in the cardiovascular system. In contrast with the short research history of the enzymatic synthesis of NO, the introduction of nitrate-containing compounds for medicinal purposes marked its 150th anniversary in 1997. Glyceryl trinitrate (nitroglycerin; GTN) is the first compound of this category. Alfred Nobel (the founder of the Nobel Prize) himself had suffered from angina pectoris and was prescribed nitroglycerin for his chest pain while he refused to take due to the induction of headaches. Almost a century after its first chemical use, research in the nitric oxide and 3',5'-cyclic guanosine monophosphate (NO/cGMP) pathway has dramatically expanded and the role of NO/cGMP in physiology and pathology has been extensively studied. Soluble guanylyl cyclase (sGC) is the receptor for NO. The α1ß1 heterodimer is the predominant isoform of sGC that is obligatory for catalytic activity. NO binds to the ferrous (Fe(2+)) heme at histidine 105 of the ß1 subunit and leads to an increase in sGC activity and cGMP production of at least 200-fold. In this chapter, we reviewed the studies of sGC-cGMP signaling in cell proliferation; introduced our work of targeting sGC-cGMP signaling for cancer therapy; and explored the role of sGC-cGMP signaling in the chromatin-microenvironment.

Hydrogen peroxide alters splicing of soluble guanylyl cyclase and selectively modulates expression of splicing regulators in human cancer cells.

BACKGROUND: Soluble guanylyl cyclase (sGC) plays a central role in nitric oxide (NO)-mediated signal transduction in the cardiovascular, nervous and gastrointestinal systems. Alternative RNA splicing has emerged as a potential mechanism to modulate sGC expression and activity. C-α1 sGC is an alternative splice form that is resistant to oxidation-induced protein degradation and demonstrates preferential subcellular distribution to the oxidized environment of endoplasmic reticulum (ER). METHODOLOGY/PRINCIPAL FINDINGS: Here we report that splicing of C-α1 sGC can be modulated by H(2)O(2) treatment in BE2 neuroblastoma and MDA-MD-468 adenocarcinoma human cells. In addition, we show that the H(2)O(2) treatment of MDA-MD-468 cells selectively decreases protein levels of PTBP1 and hnRNP A2/B1 splice factors identified as potential α1 gene splicing regulators by in silico analysis. We further demonstrate that down-regulation of PTBP1 by H(2)O(2) occurs at the protein level with variable regulation observed in different breast cancer cells. CONCLUSIONS/SIGNIFICANCE: Our data demonstrate that H(2)O(2) regulates RNA splicing to induce expression of the oxidation-resistant C-α1 sGC subunit. We also report that H(2)O(2) treatment selectively alters the expression of key splicing regulators. This process might play an important role in regulation of cellular adaptation to conditions of oxidative stress.

Curcumin induces differentiation of embryonic stem cells through possible modulation of nitric oxide-cyclic GMP pathway.

Curcumin, an active ingredient of dietary spice used in curry, has been shown to exhibit anti-oxidant, anti-inflammatory and anti-proliferative properties. Using EB directed differentiation protocol of H-9 human embryonic stem (ES) cells; we evaluated the effect of curcumin (0-20 µmol/L) in enhancing such differentiation. Our results using real time PCR, western blotting and immunostaining demonstrated that curcumin significantly increased the gene expression and protein levels of cardiac specific transcription factor NKx2.5, cardiac troponin I, myosin heavy chain, and endothelial nitric oxide synthase during ES cell differentiation. Furthermore, an NO donor enhanced the curcumin-mediated induction of NKx2.5 and other cardiac specific proteins. Incubation of cells with curcumin led to a dose dependent increase in intracellular nitrite to the same extent as giving an authentic NO donor. Functional assay for second messenger(s) cyclic AMP (cAMP) and cyclic GMP (cGMP) revealed that continuous presence of curcumin in differentiated cells induced a decrease in the baseline levels of cAMP but it significantly elevated baseline contents of cGMP. Curcumin addition to a cell free assay significantly suppressed cAMP and cGMP degradation in the extracts while long term treatment of intact cells with curcumin increased the rates of cAMP and cGMP degradation suggesting that this might be due to direct suppression of some cyclic nucleotide-degrading enzyme (phosphodiesterase) by curcumin. These studies demonstrate that polyphenol curcumin may be involved in differentiation of ES cells partly due to manipulation of nitric oxide signaling.

NOS-2 signaling and cancer therapy.

The role of NO and cGMP signaling in tumor biology has been extensively studied during the past three decades. However, whether the pathway is beneficial or detrimental in cancer is still open to question. We suggest several reasons for this ambiguity: first, although NO participates in normal signaling (e.g., vasodilation and neurotransmission), NO is also a cytotoxic or apoptotic molecule when produced at high concentrations by inducible nitric-oxide synthase (iNOS or NOS-2). In addition, the cGMP-dependent (NO/sGC/cGMP pathway) and cGMP-independent (NO oxidative pathway) components may vary among different tissues and cell types. Furthermore, solid tumors contain two compartments: the parenchyma (neoplastic cells) and the stroma (nonmalignant supporting tissues including connective tissue, blood vessels, and inflammatory cells) with different NO biology. Thus, the NO/sGC/cGMP signaling molecules in tumors as well as the surrounding tissue must be further characterized before targeting this signaling pathway for tumor therapy. In this review, we focus on the NOS-2 expression in tumor and surrounding cells and summarized research outcome in terms of cancer therapy. We propose that a normal function of the sGC-cGMP signaling axis may be important for the prevention and/or treatment of malignant tumors. Inhibiting NOS-2 overexpression and the tumor inflammatory microenvironment, combined with normalization of the sGC/cGMP signaling may be a favorable alternative to chemotherapy and radiotherapy for malignant tumors.

Targeting different types of human meningioma and glioma cells using a novel adenoviral vector expressing GFP-TRAIL fusion protein from hTERT promoter.

OBJECTIVE: The objective of this study was to evaluate the anti-tumor effects of Ad/gTRAIL (an adenoviral vector in which expression of GFP and TRAIL is driven by a human telomerase reverse transcriptase promoter, hTERT) on malignant meningiomas and gliomas. BACKGROUND: Gliomas and meningiomas are the two most common types of human brain tumors. Currently there is no effective cure for recurrent malignant meningiomas or for gliomas. Ad/gTRAIL has been shown to be effective in killing selected lung, colon and breast cancer cells, but there have been no studies reporting its antitumor effects on malignant meningiomas. Therefore, we tested the antitumor effect of Ad/gTRAIL for the first time in human malignant meningioma and glioma cell lines, and in intracranial M6 and U87 xenografts. MATERIALS AND METHODS: Human malignant meningioma and glioma cells were infected with adenoviruses, Ad/gTRAIL and Ad/CMV-GFP. Cell viability was determined by proliferation assay. FACS analysis and quantification of TRAIL were used to measure apoptosis in these cells. We injected Ad/gTRAIL viruses in intracranial M6 and U87 xenografts, and measured the brain tumor volume, quantified apoptosis by TUNEL assay in the brain tumor tissue. RESULTS: Our studies demonstrate that in vitro/in vivo treatment with Ad/gTRAIL virus resulted in significant increase of TRAIL activity, and elicited a greater tumor cell apoptosis in malignant brain tumor cells as compared to treatment with the control, Ad/CMV-GFP virus without TRAIL activity. CONCLUSIONS: We showed for the first time that adenovirus Ad/gTRAIL had significant antitumor effects against high grade malignant meningiomas as well as gliomas. Although more work needs to be done, our data suggests that Ad/gTRAIL has the potential to be useful as a tool against malignant brain tumors.