Development of the nano-dust analyzer (NDA) for detection and compositional analysis of nanometer-size dust particles originating in the inner heliosphere

A linear time-of-flight mass spectrometer is developed for the detection and chemical analysis of nanometer-sized particles originating near the Sun. Nano-dust particles are thought to be produced by mutual collisions between interplanetary dust particles slowly spiraling toward the Sun and are accelerated outward to high velocities by interaction with the solar wind plasma. The WAVES instruments on the two STEREO spacecraft reported the detection, strong temporal variation, and potentially high flux of these particles. Here we report on the optimization and the results from the detailed characterization of the instrument's performance using submicrometer sized dust particles accelerated to 8-60 km/s. The Nano Dust Analyzer (NDA) concept is derived from previously developed detectors. It has a 200 cm(2) effective target area and a mass resolution of approximately m/Δm = 50. The NDA instrument is designed to reliably detect and analyze nanometer-sized dust particles while being pointed close to the Sun's direction, from where they are expected to arrive. Measurements by such an instrument will determine the size-dependent flux of the nano-dust particles and its variations, it will characterize the composition of the nano-dust and, ultimately, it may determine their source. The flight version of the NDA instrument is estimated to be <5 kg and requires <10 W for operation.

Characterization of NADPH oxidase 5 expression in human tumors and tumor cell lines with a novel mouse monoclonal antibody

Reactive oxygen species generated by NADPH oxidase 5 (Nox5) have been implicated in physiological and pathophysiological signaling pathways, including cancer development and progression. However, because immunological tools are lacking, knowledge of the role of Nox5 in tumor biology has been limited; the expression of Nox5 protein across tumors and normal tissues is essentially unknown. Here, we report the characterization and use of a mouse monoclonal antibody against a recombinant Nox5 protein (bp 600-746) for expression profiling of Nox5 in human tumors by tissue microarray analysis. Using our novel antibody, we also report the detection of endogenous Nox5 protein in human UACC-257 melanoma cells. Immunofluorescence, confocal microscopy, and immunohistochemical techniques were employed to demonstrate Nox5 localization throughout UACC-257 cells, with perinuclear enhancement. Tissue microarray analysis revealed, for the first time, substantial Nox5 overexpression in several human cancers, including those of prostate, breast, colon, lung, brain, and ovary, as well as in malignant melanoma and non-Hodgkin lymphoma; expression in most nonmalignant tissues was negative to weak. This validated mouse monoclonal antibody will promote further exploration of the functional significance of Nox5 in human pathophysiology, including tumor cell growth and proliferation.

Abstract 4796: Characterization of NADPH oxidase 5 expression in human tumors and tumor cell lines with a novel mouse monoclonal antibody

NADPH oxidase (Nox) family enzymes (Nox1-5 and Duox1-2) generate reactive oxygen species (ROS) and modulate cellular pathways that regulate tumorigenesis. Recent studies have proposed that Nox5 plays a role in the proliferative capacity of Hairy cell leukemia, Barrett's esophageal adenocarcinoma, and in prostate cancer cells. Although implicated in several malignancies, the role of Nox5 in tumor cell biology is still unclear. This impediment is due to a lack of reliable immunological probes as well as the fact that little is known regarding Nox5 expression in human tumors. In this study, we report for the first time the generation and characterization of a mouse monoclonal antibody against a recombinant Nox5 protein (600-746), and the expression profile of Nox5 in human tumors by tissue microarray analysis. We also report the detection of endogenous Nox5 protein in the UACC-257 human melanoma cell line using our novel Nox5 antibody. Specificity of the antibody for Nox5 was confirmed by generating stable Nox5 over-expressing UACC-257 cell clones, and by transiently silencing both endogenous Nox5 and stably overexpressed Nox5. Additionally, no cross-reactivity of the antibody with other Nox homologs was detected. Sub-cellular fractionation studies revealed that Nox5 was predominantly expressed in the membranes of UACC-257 cells and its Nox5 overexpressing clones. Immunofluorescence, confocal microscopy, and immunohistochemistry demonstrated that Nox5 localizes throughout parental UACC-257 cells and Nox5 overexpressing clones, with perinuclear enhancement. To evaluate the clinical significance of Nox5 in human cancer, we determined the expression of Nox5 protein in a representative set (382 samples) of human tumors. Tissue microarray analysis revealed substantial Nox5 overexpression in several human tumors of epithelial origin including breast, colon, lung, prostate, and ovarian cancers, as well as non-epithelial malignancies (glioblastoma multiforme, melanoma, and lymphoma). Expression was markedly increased in tumors compared to normal tissues of the same organ. Collectively, our study provides the first demonstration of Nox5 overexpression in human tumors by tissue microarray, and reports on the first mouse monoclonal antibody against Nox5. The elevated expression of Nox5 in tumors provides impetus to explore the functional significance of Nox5 in the context of tumor development and maintenance.

Citation Format: Smitha Antony, Yongzhong Wu, Stephen M. Hewitt, Miriam R. Anver, Guojian Jiang, Jennifer L. Meitzler, Han Liu, Agnes Juhasz, Jiamo Lu, Krishnendu K. Roy, James H. Doroshow. Characterization of NADPH oxidase 5 expression in human tumors and tumor cell lines with a novel mouse monoclonal antibody. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4796. doi:10.1158/1538-7445.AM2013-4796

Abstract 5406: Transcriptional upregulation of NADPH Oxidase 1 (NOX1) by Interleukin-4 (IL-4) enhances tumor cell proliferation and reactive oxygen production in human colon cancer cells

Reactive oxygen species (ROS) produced by the family of NOX genes play a critical role in cytokine-mediated signal transduction in both normal and tumor tissue. Human colon cancers, compared to adjacent normal tissues, overexpress NOX1; and premalignant, chronic inflammatory conditions of the colon (ulcerative colitis, Crohn's disease) are associated with NOX up-regulation. However, a mechanistic understanding of how cytokines might increase ROS production and NOX1 expression in colon cancer remains unclear. We screened a panel of human colon cancer cells with a series of pro-inflammatory cytokines to evaluate their effects on NOX1 expression and function, as well as cell proliferation. Cytokine IL-4 significantly up-regulated NOX1 expression (but not other members of the NOX family) in HT-29 (as well as other) colon cancer cells while increasing O2• production and growth; decreasing NOX1 expression by 90% in stable, NOX1-shRNA-containing HT-29 clones blocked IL-4-related enhancement of cell growth, NOX1 expression, or ROS production. IL-4 up-regulated and activated the GATA3 transcription factor in addition to the Jak1-Stat6 pathway in HT-29 cells. GATA3 played an important role in the transcriptional up-regulation of NOX1 by IL-4; RNAi-mediated silencing of Jak1, Stat6, or GATA3 expression attenuated IL-4-induced NOX1 up-regulation in HT-29 cells. Transient overexpression of GATA3 cDNA in the presence of IL-4 resulted in a further increase in NOX1 expression with enhanced ROS activity beyond IL-4 treatment alone. Using an 1139 bp segment of upstream sequence from the transcription start site of the human NOX1 promoter as a promoter-reporter assay, we found that IL-4 treatment increased NOX1 reporter gene transcription 4-fold in HT-29 cells. DNA sequence analysis of this upstream promoter suggests the presence of four putative GATA3 binding, cis-active elements that may be sufficient for maximal IL-4-enahanced activity of the NOX1 promoter. Ongoing mutational analysis of the NOX1 promoter will further define the role of GATA3 in the control of NOX1 transcriptional up-regulation by IL-4. In summary, our results support a role for IL-4 in producing a NOX1-dependent pro-oxidant milieu that could increase the growth potential of colon cancer cells.

Citation Format: Han Liu, Agnes Juhasz, Guojian Jiang, Smitha Antony, Jennifer L. Meitzler, Yongzhong Wu, Jiamo Lu, Krishnendu Roy, James H. Doroshow. Transcriptional upregulation of NADPH Oxidase 1 (NOX1) by Interleukin-4 (IL-4) enhances tumor cell proliferation and reactive oxygen production in human colon cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5406. doi:10.1158/1538-7445.AM2013-5406

Effects of iodonium-class flavin dehydrogenase inhibitors on growth, reactive oxygen production, cell cycle progression, NADPH oxidase 1 levels, and gene expression in human colon cancer cells and xenografts

Iodonium-class flavoprotein dehydrogenase inhibitors have been demonstrated to possess antiproliferative potential and to inhibit reactive oxygen production in human tumor cells, although the mechanism(s) that explains the relationship between altered cell growth and the generation of reactive oxygen species (ROS) remains an area of active investigation. Because of the ability of these compounds to inhibit the activity of flavoprotein-containing epithelial NADPH oxidases, we chose to examine the effects of several iodonium-class flavoprotein inhibitors on human colon cancer cell lines that express high, functional levels of a single such oxidase (NADPH oxidase 1, or Nox1). We found that diphenyleneiodonium (DPI), di-2-thienyliodonium (DTI), and iodonium diphenyl inhibited the growth of Caco2, HT-29, and LS-174T colon cancer cells at concentrations (10-250nM for DPI, 0.5-2.5μM for DTI, and 155nM to 10μM for iodonium diphenyl) substantially lower than needed for DU145 human prostate cancer cells, which do not possess functional NADPH oxidase activity. Drug treatment was associated with decreased H2O2 production and diminished intracellular ROS levels, lasting up to 24h, after short-term (1-h) exposure to the iodonium analogs. Decreased tumor cell proliferation was caused, in part, by a profound block in cell cycle progression at the G1/S interface in both LS-174T and HT-29 cells exposed to either DPI or DTI; and the G1 block was produced, for LS-174T cells, by upregulation of p27 and a drug concentration-related decrease in the expression of cyclins D1, A, and E that was partially prevented by exogenous H2O2. Not only did DPI and DTI decrease intracellular ROS, they both also significantly decreased the mRNA expression levels of Nox1, potentially contributing to the prolonged reduction in tumor cell reactive oxygen levels. We also found that DPI and DTI significantly decreased the growth of both HT-29 and LS-174T human tumor xenografts, at dose levels that produced peak plasma concentrations similar to those utilized for our in vitro experiments. These findings suggest that iodonium analogs have therapeutic potential for NADPH oxidase-containing human colon cancers in vivo and that at least part of their antineoplastic mechanism of action may be related to targeting Nox1.

Activation of TLR4 is required for the synergistic induction of dual oxidase 2 and dual oxidase A2 by IFN-γ and lipopolysaccharide in human pancreatic cancer cell lines

Pancreatitis is associated with release of proinflammatory cytokines and reactive oxygen species and plays an important role in the development of pancreatic cancer. We recently demonstrated that dual oxidase (Duox)2, an NADPH oxidase essential for reactive oxygen species-related, gastrointestinal host defense, is regulated by IFN-γ-mediated Stat1 binding to the Duox2 promoter in pancreatic tumor lines. Because LPS enhances the development and invasiveness of pancreatic cancer in vivo following TLR4-related activation of NF-κB, we examined whether LPS, alone or combined with IFN-γ, regulated Duox2. We found that upregulation of TLR4 by IFN-γ in BxPC-3 and CFPAC-1 pancreatic cancer cells was augmented by LPS, resulting in activation of NF-κB, accumulation of NF-κB (p65) in the nucleus, and increased binding of p65 to the Duox2 promoter. TLR4 silencing with small interfering RNAs, as well as two independent NF-κB inhibitors, attenuated LPS- and IFN-γ-mediated Duox2 upregulation in BxPC-3 cells. Induction of Duox2 expression by IFN-γ and LPS may result from IFN-γ-related activation of Stat1 acting in concert with NF-κB-related upregulation of Duox2. Sustained extracellular accumulation of H(2)O(2) generated by exposure to both LPS and IFN-γ was responsible for an ∼50% decrease in BxPC-3 cell proliferation associated with a G(1) cell cycle block, apoptosis, and DNA damage. We also demonstrated upregulation of Duox expression in vivo in pancreatic cancer xenografts and in patients with chronic pancreatitis. These results suggest that inflammatory cytokines can interact to produce a Duox-dependent pro-oxidant milieu that could increase the pathologic potential of pancreatic inflammation and pancreatic cancer cells.

Functional activity and tumor-specific expression of dual oxidase 2 in pancreatic cancer cells and human malignancies characterized with a novel monoclonal antibody

Dual oxidase 2 (Duox2), one of the seven members of the NADPH oxidase gene family, plays a critical role in generating H₂O₂ for thyroid hormone biosynthesis and as an integral part of the host defense system of the respiratory epithelium and the gastrointestinal tract. Recent evidence suggests that the regulation of Duox2 expression is under the control of pro-inflammatory cytokines and that Duox2-induced reactive oxygen species (ROS) contribute to the inflammation-related tissue injury that occurs in two pre-malignant, inflammatory conditions: chronic pancreatitis and inflammatory bowel disease. Because no reliable Duox antibodies are commercially available, we report the development of a murine monoclonal antibody (MAb) to Duox2 (clone Duox S-12) and its use for the characterization of Duox2 expression in human tumors, tumor cell lines and normal tissues. Duox S-12 specifically detected both endogenously- and ectopically-expressed Duox2 protein by immunoblotting, immunofluorescence microscopy and immunohistochemistry (where both membranous and cytoplasmic staining were present). Duox2 expression detected by Duox S-12 was functionally coupled to the generation of H₂O₂ in pancreatic cancer cells that expressed Duox2 and its cognate maturation factor DuoxA2. Although Duox S-12 recognizes ectopically expressed Duox1 protein because of the extensive amino acid homology between Duox1 and Duox2, the lack of substantial Duox1 mRNA expression in human tumors (except thyroid cancer) allowed us to evaluate Duox2 expression across a wide range of normal and malignant tissues by immunohistochemistry. Duox2 was expressed at elevated levels in many human cancers, most notably tumors of the prostate, lung, colon and breast while brain tumors and lymphomas demonstrated the lowest frequency of expression. The Duox-specific monoclonal antibody described here provides a promising tool for the further examination of the role of Duox-dependent reactive oxygen production in inflammation-related carcinogenesis, where alterations in oxidant tone play a critical role in cell growth and proliferation.

Abstract 3066: Effect of stable knockdown of NOX1 gene expression with siRNA in human colon cancer cells

NADPH oxidase (Nox)-dependent reactive oxygen species (ROS) play a critical role in cell signaling, cell proliferation, and mitogenesis. We have previously shown that silencing NOX1 gene expression with siRNA decreases cell growth and angiogenesis in human HT-29 colon cancer xenografts. To investigate the mechanism of growth inhibition, we studied cell cycle and signaling pathways. We found using RT-PCR and Western analysis that the expression of the INK4 inhibitors (p15, p18, p19), as well as CDK6, phospho-Cyclin E, Cyclin E, and Cyclin D1 were all decreased when NOX1 was decreased by &gt;80%. We detected important changes in the Raf-MEK-ERK pathway that were associated with NOX1 knockdown. Our stable knock-out cells (clone 6A) showed lower phosphorylation of Rac1, c-Raf, MEK1/2, ERK1/2, p90RSK and CREB. To understand this observation, we studied the activity of Tyr and Ser/Threonine protein phosphatases (PP) in our stable siRNA containing cells (6A) compared to stable scrambled siRNA containing cells (SA) and parental HT-29 cells. PTP1B activity was elevated (100.4+4.4 pmol of phosphate/min/µg) in 6A cells compared to both SA (69.2+3.8) and parental (47.8+2.1) cell controls, P&lt;0.05. Serine/Threonine protein phosphatases demonstrated a similar pattern; elevated in 6A cells (127.3+3.8 pmol of phosphate/min/µg) versus both SA cells (91.7+2.1) and the parental line (88.9+1.9), P&lt;0.05. To demonstrate that protein phosphatases play a key role in the regulation of ERK-CREB signaling, we used a c-Raf antibody to immunoprecipitate the c-Raf-PPs complex, and detected PTP1B and PP2C proteins by Western analysis. These data indicate that siRNA-mediated gene silencing of Nox1 deactivated ERK-CREB signaling, and that increased activity of protein phosphatases, that occur as a consequence of decreased Nox-mediated ROS formation, might play role in modifying the growth enhancing effects of the MAP kinase pathway in HT-29 colon cancer cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3066. doi:1538-7445.AM2012-3066

Abstract 2060: NADPH oxidase NOX5 regulates the expression of the cell cycle inhibitor p27kip1 in the human melanoma UACC-257 cancer cells

NADPH oxidase (NOX) family enzymes (NOX1-5 and DUOX1-2) generate reactive oxygen species (ROS) and modulate cellular pathways that regulate proliferation. While high doses of ROS are clearly toxic, the effects of low doses of NOX-mediated ROS as signaling molecules are less clear. Recent work has proposed that NOX5 plays a role in cell proliferation in Hairy cell leukemia, Barrett's esophageal adenocarcinoma and in prostate cancer cells, yet relatively little is known of the signaling pathways mediated by NOX5. In this study we explored the functional role of NOX5 in cancer cells obtained from the NCI-60 cell line panel. Initial screening of the NCI-60 cancer cell line panel for expression of the Nox family members by real time PCR revealed several melanoma cell lines that express Nox5. Of the NOX5 expressing NCI-60 human cancer cell lines, subsequent studies were carried out in human UACC-257 melanoma cancer cells. Two molecular approaches were undertaken to determine the functional role of NOX5 in UACC-257 cells: 1) generating NOX5 over-expressing stable clones and 2) transiently silencing endogenous NOX5 and the stably over-expressed NOX5. Redox-sensitive assays for both intra- and extracellular ROS production confirmed that NOX5 is functional and generates superoxide in both UACC-257 cells and stable Nox5-over-expressing clones. NOX5 can be activated both by the protein kinase C activating phorbol ester PMA and by the Ca2+ ionophore ionomycin. Furthermore, this enzymatic activity is calcium- and flavin dehydrogenase-dependent; both the calcium chelator BAPTA-AM and the flavoprotein inhibitor DPI (200nM) significantly decreased NOX5-mediated ROS production. Silencing NOX5 over-expression significantly inhibited both endogenous and PMA-stimulated ROS production, suggesting that the ROS production is NOX5-mediated. Furthermore, knockdown of both endogenous and over-expressed NOX5 in UACC-257 cells resulted in increased p27Kip1 expression. Conversely, over-expression of NOX5 in UACC-257 cells resulted in decreased p27Kip1 expression both at the mRNA and protein levels. As the AKT signaling pathways are known to modulate p27Kip1 levels, we observed that knockdown of both endogenous and over-expressed NOX5 in UACC-257 cells resulted in decreased Akt and GSK-3β phosphorylation. Studies to characterize additional mechanisms of translational and transcriptional regulation of p27Kip1 by NOX5 are ongoing. In summary, our findings suggest that NOX5 expression could contribute to cell proliferation in human cancers in part due to the generation of high local concentrations of extracellular ROS that regulate the Akt/GSK-3β/p27Kip1 signaling network.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2060. doi:1538-7445.AM2012-2060

Abstract 3094: Interferon-α induced TLR4 is indispensable for the synergistic induction of Duox2/DuoxA2 by lipopolysacharide (LPS) and IFN-γ in human pancreatic cancer cells

Several bacterial cell wall components, including lipopolysaccharide (LPS), muramyldipeptide (MDP), and flagellin, have been shown to engage their corresponding receptors and mediate NADPH oxidase (NOX)-dependent reactive oxygen species (ROS) generation that may be involved in wound healing, host defense, and the inflammatory response in airway and gastrointestinal epithelial cells. Previously, we reported that two human pancreatic cancer cell lines, BxPC-3 and AsPC-1, respond to the pro-inflammatory cytokine IFN-γ by upregulating the expression of both Dual oxidase 2 and its cognate cofactor DuoxA2 resulting in enhanced ROS production. It has also been reported that human pancreatic cancer cells express TLR4/MyD88, and that signaling downstream of the TLR receptor may be responsible for LPS-induced invasiveness of pancreatic cancer cells. In our studies, we have demonstrated that IFN-γ up-regulates TLR4 and its adaptor protein MyD88 expression in BxPc-3 cells and augments the response of these cells to LPS, resulting in the activation of NFkB signaling, enhancing p65 subunit accumulation in the nucleus. Moreover, we found that p65 binds to the Duox2 promoter, and cooperates with the IFN-γ- induced Stat1 expression to synergistically enhance Duox2/DuoxA2 expression, leading to persistent intra- and extracellular ROS accumulation. TLR4 silencing by RNAi and two independent NF-kB inhibitors (PDTC and BAY11-70829) specifically attenuate LPS- and IFN-γ-mediated Duox2 expression in BxPc-3 cells, underscoring the importance of TLR4 engagement and the activation of NF-kB signaling in regulating Duox2 expression and subsequent ROS generation by LPS and IFN-γ. Our data suggest that sustained extracellular H2O2 accumulation, mediated by LPS- and IFN-γ- induced Duox2/DuoxA2 expression, may contribute to the deleterious effects of cytokine-mediated pancreatic inflammation.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3094. doi:1538-7445.AM2012-3094

Abstract 4205: Regulation of Hif-1α expression by NADPH oxidase 5 (Nox5) in human cancer cell lines

Reactive oxygen species (ROS) produced by NADPH oxidases (Noxs) participate in signaling cascades regulating proliferation. However, the relative contribution to tumor cell growth by the seven Nox homologues (Nox1-5 and Duox 1 and 2) remains unclear. Several studies have proposed that Nox5 plays a role in promoting cell proliferation in Hairy cell leukemia, Barrett's esophageal adenocarcinoma cells, and in prostate cancer; however, little is known about the signaling pathways mediated by Nox5. We explored the functional role of Nox5 in a variety of tumor cell lines, including the NCI-60 cell panel; real time RT-PCR revealed that several melanoma lines express Nox4 and Nox5, but no Nox1 mRNA; and that prostate cell lines express Nox5 mRNA. Of the Nox5- expressing NCI-60 human cancer cell lines, we studied UACC-257 melanoma and PC-3 prostate cancer cells. These lines were characterized for variations in their N-terminus Ca2+ binding domains; RT-PCR revealed that both cell lines expressed the Nox5α and Nox5γ forms. The functional role of Nox5 in UACC-257 and PC-3 cells was studied by generating stable Nox5-overexpressing clones, and by transiently silencing Nox5 that was expressed endogenously, as well as that in clones stably overexpressing Nox5. Redox-sensitive assays for both intra- and extracellular ROS production confirmed that Nox5 was functional and generated superoxide in UACC-257 and PC-3 clones overexpressing Nox5. Nox5 could be activated by the phorbol ester PMA and by the Ca2+ ionophore ionomycin in overexpressing clones. This enzymatic activity was Ca2+- and flavin dehydrogenase-dependent; the calcium chelator BAPTA-AM and the flavoprotein inhibitor DPI (200nM) significantly decreased Nox5-mediated ROS production. Overexpression of Nox5 in UACC-257 cells resulted in increased normoxic Hif-1α expression that was also Ca2+-, flavin dehydrogenase- and ROS-dependent. Silencing Nox5 by RNAi significantly inhibited both endogenous and PMA-stimulated ROS production, confirming that ROS production was Nox5-mediated. Knockdown of both endogenous and overexpressed Nox5 in both UACC-257 and PC-3 cells resulted in decreased Hif-1α expression. Studies to characterize the mechanisms by which Nox5 modulates cell proliferation through the HIF-1α pathway are ongoing. Our experiments suggest that Nox5 expression may play an important role in the generation of high local concentrations of ROS that could contribute to activation of Hif-1α and promote cell proliferation in human cancers.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4205. doi:10.1158/1538-7445.AM2011-4205

Up-regulation and sustained activation of Stat1 are essential for interferon-gamma (IFN-gamma)-induced dual oxidase 2 (Duox2) and dual oxidase A2 (DuoxA2) expression in human pancreatic cancer cell lines

Dual oxidase 2 is a member of the NADPH oxidase (Nox) gene family that plays a critical role in the biosynthesis of thyroid hormone as well as in the inflammatory response of the upper airway mucosa and in wound healing, presumably through its ability to generate reactive oxygen species, including H2O2. The recently discovered overexpression of Duox2 in gastrointestinal malignancies, as well as our limited understanding of the regulation of Duox2 expression, led us to examine the effect of cytokines and growth factors on Duox2 in human tumor cells. We found that exposure of human pancreatic cancer cells to IFN-γ (but not other agents) produced a profound up-regulation of the expression of Duox2, and its cognate maturation factor DuoxA2, but not other members of the Nox family. Furthermore, increased Duox2/DuoxA2 expression was closely associated with a significant increase in the production of both intracellular reactive oxygen species and extracellular H2O2. Examination of IFN-γ-mediated signaling events demonstrated that in addition to the canonical Jak-Stat1 pathway, IFN-γ activated the p38-MAPK pathway in pancreatic cancer cells, and both played an important role in the induction of Duox2 by IFN-γ. Duox2 up-regulation following IFN-γ exposure is also directly associated with the binding of Stat1 to elements of the Duox2 promoter. Our findings suggest that the pro-inflammatory cytokine IFN-γ initiates a Duox2-mediated reactive oxygen cascade in human pancreatic cancer cells; reactive oxygen species production in this setting could contribute to the pathophysiologic characteristics of these tumors.

Relationship of adipokines and non-esterified fatty acid to the insulin resistance in non-diabetic individuals

BACKGROUND

Altered secretion of adipokines and non-esterified fatty acid (NEFA) seems to play a pivotal role in the abdominal obesity-related insulin resistance (IR).

AIM

To determine semi-quantitatively the impact of serum NEFA, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), leptin, adiponectin, and resistin levels on IR measured by homeostasis model assessment (HOMA-IR). MATERIAL/SUBJECTS: Seventy-four Caucasian subjects forming 3 age-, and sex-matched groups were included into the study [Group 1 and 2: non-diabetic obese patients, no.= 25, body mass index (BMI): 28-39.9 kg/m(2), no.=25, BMI≥40 kg/m(2), respectively, and Group 3: 24 healthy, normal weight control subjects].

METHODS

Serum levels of NEFA and adipokines as well as other metabolic variables including HOMA-IR were measured.

RESULTS

HOMA-IR was associated positively with BMI, waist circumference, serum NEFA, leptin, IL-6, and TNF-α levels, negatively with adiponectin, with no significant relation to resistin. In multiple regression analyses, of these factors leptin was a strong, IL-6 and adiponectin were weak independent predictors of HOMA-IR, while the others were not significant determinants of HOMA-IR. However, even together, they explained only 35-36% of variance of HOMAIR.

CONCLUSIONS

Although IR has associations with many of the investigated parameters, of these, only serum level of leptin, and in lesser degree IL-6 and adiponectin are independent determinants of the severity of IR. Moreover, even together they explain only a minority of variance IR.

A phase II study of the antisense oligonucleotide GTI-2040 plus docetaxel and prednisone as first-line treatment in castration-resistant prostate cancer

PURPOSE

GTI-2040 is a novel antisense oligonucleotide to the R2 subunit of ribonucleotide reductase. This phase II trial was conducted to determine the efficacy and tolerability of GTI-2040 when combined with docetaxel and prednisone for the treatment of patients with castration-resistant prostate cancer (CRPC).

METHODS

Chemo-naïve CRPC patients with adequate performance status and organ function were treated with docetaxel 75 mg/m(2) IV on day 1 plus GTI-2040 5 mg/kg/day by continuous intravenous infusion day 1-14 on a 21 day cycle, with prednisone 5 mg orally twice daily. The primary endpoint was PSA response rate. Pharmacokinetic studies of GTI-2040 and pharmacodynamic studies on peripheral blood mononuclear cells (PBMC) were also performed.

RESULTS

Twenty-two patients in total (19 from this study and 3 from a prior phase I/II study at this institution) were treated at the recommended phase II dose. A confirmed PSA response was seen in 9/22 patients (41%). Of 16 patients with measurable disease, there was 1 partial response (PR) and 12 stable disease (SD) lasting 3.6 months (median), as best response. The most common toxicities were anemia, fatigue, lymphopenia, leucopenia and neutropenia. Grade 3+ toxicities included neutropenia, lymphopenia, leucopenia, fatigue, febrile neutropenia and hypophosphatemia.

CONCLUSIONS

The PSA response rate of GTI-2040 in combination with docetaxel and prednisone just met the minimum phase II criteria for further enrollment. However, after evaluation of all the clinical data, further study of this dose and schedule of GTI-2040 in CRPC was not recommended.

Abstract 4012: Upregulation and sustained activation of Stat1 are essential for IFN-γ-induced Duox2/DuoxA2 expression in the human pancreatic cancer cell line BxPc3

Pancreatic inflammation accelerates the development of pancreatic cancer, possibly due to cytokine release and the generation of reactive oxygen species (ROS). Recently, it has been documented that pancreatic tumor cells frequently produce higher concentrations of ROS than their normal cellular counterparts. Although ROS at high concentration may be cytotoxic, physiologic ROS levels play a critical role in the control of tumor cell proliferation and signal transduction. Membrane-bound, epithelial NADPH oxidase (NOX) flavoproteins are major sources of ROS in tumor cells. Dual oxidase 2 (DUOX2) is one member of the NOX gene family; it was originally identified in the thyroid gland as the H2O2-generating enzyme responsible for thyroid hormone biosynthesis. Recently, DUOX2 also has been found in upper airway mucosa and throughout the gastrointestinal tract. Duox2 is a membrane glycoprotein with a unique N-terminal heme peroxidase-like domain as well as a membrane-spanning NAD(P)H oxidase domain, with an additional cytosolic segment containing two calcium-binding domains that generate H2O2 in the extracellular milieu. The associated dual oxidase maturation factor 2 (DUOXA2), an ER-resident protein, is absolutely necessary for posttranslational processing and translocation of DUOX2 to the plasma membrane to produce functional enzymatic activity. Because of the proposed growth promotion and proinflammatory role of DUOX2, we screened a panel of cytokines to determine whether they modulate DUOX2-mediated ROS production. Among several pancreatic cancer cell lines evaluated, BxPc3 is specifically and highly responsive to IFN-γ for the induction of both Duox2 and DuoxA2 mRNA, and Duox2 protein, in a time-dependent as well as concentration-dependent manner. Redox-sensitive assays for both intra- and extracellular ROS production confirmed that IFN-γ-induced Duox2 and DuoxA2 mRNA expression correlates with DUOX2 enzymatic activity. This enzymatic activity is calcium- and flavin dehydrogenase-dependent; both the calcium chelator BAPTA-AM and the flavoprotein inhibitor DPI (200nM) significantly decreased IFN-γ-mediated ROS production. BxPc3 cell exposure to actinomycin D or cyclohexamide demonstrated that IFN-γ-mediated Duox2 and DuoxA2 expression were both transcriptionally regulated; new protein synthesis also appeared to be absolutely necessary for the upregulation of Duox2 by IFN-γ. siRNA blockade of stat1 signaling revealed that upregulation and sustained activation of stat1 plays an important role in IFN-γinduced Duox2 expression in BxPc3 cells. In summary, these experiments suggest that upregulation of DUOX2 by IFN-γ-related stimulation of the stat1 pathway may play an important role in the generation of high local concentrations of extracellular ROS that could contribute to a pro-inflammatory milieu in the pancreas.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4012.

Expression of NADPH oxidase homologues and accessory genes in human cancer cell lines, tumours and adjacent normal tissues

The family of NADPH oxidase (NOX) genes produces reactive oxygen species (ROS) pivotal for both cell signalling and host defense. To investigate whether NOX and NOX accessory gene expression might be a factor common to specific human tumour types, this study measured the expression levels of NOX genes 1-5, dual oxidase 1 and 2, as well as those of NOX accessory genes NoxO1, NoxA1, p47(phox), p67(phox) and p22(phox) in human cancer cell lines and in tumour and adjacent normal tissue pairs by quantitative, real-time RT-PCR. The results demonstrate tumour-specific patterns of NOX gene expression that will inform further studies of the role of NOX activity in tumour cell invasion, growth factor response and proliferative potential.

Human papillomavirus infection as a prognostic factor in oropharyngeal squamous cell carcinomas treated in a prospective phase II clinical trial

The aim of this study was to determine the presence of high-risk HPV-16 in patients with HNSCC, assess the impact of HPV status on treatment response and survival in this select cohort treated with combined modality therapy and to identify the differences in HIF-1alpha and VEGF expression in HPV-positive and -negative tumors.

PATIENTS AND METHODS

Patients had resectable, untreated stage III, IV HNSCC of the oral cavity, oropharynx, hyopharynx or larynx, and stage II cancer of the base of tongue, hypopharynx and larynx. HPV status was determined by conventional PCR in fresh frozen biopsy samples and by Taqman PCR assay on formalin-fixed, paraffin-embedded specimens. HIF-1alpha and VEGF expression were assessed by quantitative real-time PCR (RT-PCR). Multivariate Cox proportional hazards regression analysis was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) based on HPV status.

RESULTS

HPV-16 was detected in 14 of 24 evaluable cases. There were no significant differences in response rates after neoadjuvant chemotherapy (86% vs. 90%) in HPV-positive and HPV-negative patients, respectively. There was a trend toward better progression-free (HR=0.15, 95% CI=0.002-12.54; p=0.06) and overall survival (HR=0.14, 95% CI=0.001-14.12; p=0.10) for HPV-positive patients. In a subset of 13 fresh frozen samples, RT-PCR revealed a significant increase in VEGF mRNA levels in HPV-positive tumors (p<0.01). No difference was seen for HIF-1alpha expression.

CONCLUSION

HPV presence portended a better prognosis in patients with oropharyngeal SCC treated with a multimodality treatment in a prospective clinical trial. The level of VEGF mRNA was up-regulated in HPV-16-positive tumors possibly through an HIF-1 independent manner.

Identification of F-box/LLR-repeated protein 17 as potential useful biomarker for breast cancer therapy

BACKGROUND

The expression and activity of ribonucleotide reductase (RR) has been associated with resistance to multiple drugs in human cancer. The use of antisense oligonucleotide drug, GTI-2040, a 20-mer phosphorothioate oligonucleotide complemented to the human RR M2 subunit mRNA, represents an effective strategy for inhibiting RR. The increased specificity due to the anti-resistance effect of GTI-2040 may also lead to a more favorable therapeutic outcome.

MATERIALS AND METHODS

To understand the molecular mechanism underlying RR inhibition, patients' blood samples were analyzed using multiple dimensional proteomics technology via matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) mass spectrometry.

RESULTS

A major difference occurred at 5k m/z in the MALDI profile, which appeared only in the non-responsive group and diminished after GTI-2040 treatment. This specific peptide peak remained at the basal level in responsive patients. The peak was identified to represent the F-box/LLR-repeat protein 17 (FBXL17) through nanoelectrospray ionization liquid chromatography-tandem mass spectrometry (nanoESI LC-MS/MS). Further characterization revealed that FBXL17 [corrected] directly interacts with the human RR M2 (RRM2) subunit to promote hRRM2 overexpression in the breast cancer cell line MCF-7.

CONCLUSION

Validation of this protein using real-time RT-PCR indicates the F-box protein 17 (FBXL17) can serve as a therapeutic target and surrogate marker for breast cancer therapy.