Exogenous DNA enhances DUOX2 expression and function in human pancreatic cancer cells by activating the cGAS-STING signaling pathway

Pro-inflammatory cytokines upregulate the expression of the H2O2-producing NADPH oxidase dual oxidase 2 (DUOX2)2 which, when elevated, adversely affects survival from pancreatic ductal adenocarcinoma (PDAC). Because the cGAS-STING pathway is known to initiate pro-inflammatory cytokine expression following uptake of exogenous DNA, we examined whether activation of cGAS-STING could play a role in the generation of reactive oxygen species by PDAC cells. Here, we found that a variety of exogenous DNA species markedly increased the production of cGAMP, the phosphorylation of TBK1 and IRF3, and the translocation of phosphorylated IRF3 into the nucleus, leading to a significant, IRF3-dependent enhancement of DUOX2 expression, and a significant flux of H2O2 in PDAC cells. However, unlike the canonical cGAS-STING pathway, DNA-related DUOX2 upregulation was not mediated by NF-κB. Although exogenous IFN-β significantly increased Stat1/2-associated DUOX2 expression, intracellular IFN-β signaling that followed cGAMP or DNA exposure did not itself increase DUOX2 levels. Finally, DUOX2 upregulation subsequent to cGAS-STING activation was accompanied by the enhanced, normoxic expression of HIF-1α and VEGF-A as well as DNA double strand cleavage, suggesting that cGAS-STING signaling may support the development of an oxidative, pro-angiogenic microenvironment that could contribute to the inflammation-related genetic instability of pancreatic cancer.

Abstract 2915: Synergistic, cytokine mediated stimulation (IL-1α/β + IL-6) of colon cancer cells reveals a novel mechanism of DNA damage facilitated by up-regulation of NOX1 and DUOX2

Inflammatory bowel diseases are states of long-term inflammation of the colon resulting from an interplay of environmental factors and dysregulated immune responses. As inflammatory exposure increases over the time frame of active disease, patients with these chronic conditions are at risk of developing colorectal cancers. Chronic inflammation is thought to contribute to cancer initiation through persistent release of reactive oxygen species (ROS), leading to genome damage. Accumulating evidence suggests inflammatory cells contribute to this process, as the secretion of cytokines and growth factors in response to gut inflammation also supports cancer cell progression. Specifically, IL-1 family members play a pivotal role in the pathogenesis of acute and chronic intestinal inflammation, regulating both innate and adaptive immune responses. To elucidate a direct link between IL-1 family cytokines, ROS generation and colorectal cancer, we observed that treatment of HT29 or T84 cells with IL-1α or IL-1β, in cooperation with IL-6, resulted in oxidant production through up-regulation of both NOX1 and DUOX2 enzymes. Up-regulation of the hydrogen peroxide generating DUOX2/DUOXA2 enzyme complex was directly associated with enhanced histone H2AX phosphorylation (γH2AX), a marker of DNA double strand breaks. Interestingly, this concentration and time-dependent induction of expression and oxidative response was absent in Caco2 cells and was not mediated by other IL-1 family members (IL-18, IL-33 or IL-37). Prior studies from our group have demonstrated significant up-regulation of DUOX2 and DUOXA2 in surgically resected colon cancer specimens compared with adjacent normal colonic epithelium. Future studies will focus on cytokine stimulation of colon organoids derived from patient tumor and adjacent non-malignant tissues to evaluate enzymatic expression and oxidant level changes in a novel patient-derived colon model system.

Citation Format: Jennifer L. Meitzler, Yongzhong Wu, Agnes Juhasz, Annamaria Rapisarda, Petreena Campbell, Becky A. Diebold, Smitha Antony, Guojian Jiang, Jiamo Lu, David J. Mallick, Mariam M. Konaté, Krishnendu Roy, James H. Doroshow. Synergistic, cytokine mediated stimulation (IL-1α/β + IL-6) of colon cancer cells reveals a novel mechanism of DNA damage facilitated by up-regulation of NOX1 and DUOX2 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2915.

Abstract 3571: Oxidative stress and the ovarian surface epithelium: TGF-β1 stimulation of IOSE cell lines reveals novel upregulation of NADPH oxidase 4, a membrane bound hydrogen peroxide producing enzyme

Normal ovarian surface epithelium (OSE) has been widely studied as the origin of ovarian cancer. Repetitive ovulation has been implicated in cancer initiation based on damage and inflammation incurred to the OSE upon continuous cycles of tear and repair. Transforming growth factor-beta (TGF-β) plays a role in this normal ovulatory cycle, having been shown to inhibit human OSE proliferation and induce apoptosis, which may prevent the over-proliferation of cells. NADPH oxidase 4 (NOX4), a membrane-associated hydrogen peroxide-producing enzyme, has previously been shown to be sensitive to TGF-β1, with increased expression stimulated in smooth muscle cells and fibroblasts. Here we describe for the first time TGF-β1 induced upregulation of NOX4 in immortalized OSE (IOSE) cells (IOSE121, IOSE144, IOSE364, IOSE386 and IOSE397). This time-dependent increased expression (>5 fold at 2 ng/ml TGF-β1, 24 h) was simulated by direct overexpression of NOX4 in IOSE397 cells and has demonstrated that increased NOX4, in the absence of further growth factor related effects, affords induction of p18 and p21. In addition, using immunohistochemical evaluation of human ovarian cancers in tissue microarrays (n=17 patients), we observed significantly increased expression of NOX4, suggesting that NOX4 upregulation may contribute to the malignant transformation of ovarian cells.

Citation Format: Jennifer L. Meitzler, Becky A. Diebold, Smitha Antony, Yongzhong Wu, Agnes Juhasz, Iris Dahan, Guojian Jiang, Jiamo Lu, Stephen Wang, Mariam M. Konaté, Krishnendu Roy, James H. Doroshow. Oxidative stress and the ovarian surface epithelium: TGF-β1 stimulation of IOSE cell lines reveals novel upregulation of NADPH oxidase 4, a membrane bound hydrogen peroxide producing enzyme [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3571.

Abstract 3348: Exogenous DNA upregulates DUOX2 expression in pancreatic cancer via activation of the cGAS-STING signaling pathway

Dual oxidase 2 (DUOX2) is a transmembrane protein that produces hydrogen peroxide in the extracellular environment, mediates innate immunity at mucosal surfaces, contributes to chronic inflammation-related tissue injury and angiogenesis, and can promote the initiation of epithelial-derived cancers. In pancreatic adenocarcinomas (PDAC), the composition of the tumor microbiome significantly affects patient outcomes. However, it remains unclear how microbes in the tumor microbiome affect PDAC on a cellular level. In recent years, the cGAS-STING signaling pathway has been identified as a crucial mediator of anti-viral defense by recognizing the presence of DNA in the cytosol and subsequently producing Type I interferons (IFNs) as well as a host of other anti-viral genes. Using Western blot and qPCR, we show that the introduction of exogenous DNA into the cytosol significantly upregulates DUOX2 expression in human PDAC cells after activating cGAS-STING signaling. Expression of DUOX2 occurs most strongly 2 days post-transfection of DNA, while cGAS-STING signaling is activated within hours. Treatment of BxPC-3 cells with exogenous cyclic GMP-AMP (cGAMP) for 24 hrs increases DUOX2 expression in a concentration-dependent manner, suggesting the necessity of cGAS activity for DUOX2 induction. Furthermore, Western analysis of phospho-NF-κB p65 in BxPC-3 cells demonstrates activation of NF-κB that mirrors the time-dependent induction of DUOX2. In CFPAC-1 cells, another PDAC line, Jak-Stat signaling is activated along with the components of cGAS-STING. These data suggest that DNA-induced DUOX2 upregulation in PDAC cells may be mediated in a cell context-specific fashion, beyond the canonical components of the cGAS-STING pathway. Upregulation of DUOX2 by exogenous DNA is not observed in colon cancer cell lines. In summary, these data suggest that extracellular DNA could contribute to a DUOX2-induced, H2O2-mediated pro-inflammatory milieu that specifically contributes to the pathogenesis of PDAC, in part through activation of the cGAS-STING pathway.

Citation Format: Stephen L. Wang, Yongzhong Wu, Smitha Antony, Agnes Juhasz, Jennifer Meitzler, Goujian Jiang, Iris Dahan, Jiamo Lu, Krishnendu Roy, James Doroshow. Exogenous DNA upregulates DUOX2 expression in pancreatic cancer via activation of the cGAS-STING signaling pathway [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3348.

NADPH oxidase 1 is highly expressed in human large and small bowel cancers

To facilitate functional investigation of the role of NADPH oxidase 1 (NOX1) and associated reactive oxygen species in cancer cell signaling, we report herein the development and characterization of a novel mouse monoclonal antibody that specifically recognizes the C-terminal region of the NOX1 protein. The antibody was validated in stable NOX1 overexpression and knockout systems, and demonstrates wide applicability for Western blot analysis, confocal microscopy, flow cytometry, and immunohistochemistry. We employed our NOX1 antibody to characterize NOX1 expression in a panel of 30 human colorectal cancer cell lines, and correlated protein expression with NOX1 mRNA expression and superoxide production in a subset of these cells. Although a significant correlation between oncogenic RAS status and NOX1 mRNA levels could not be demonstrated in colon cancer cell lines, RAS mutational status did correlate with NOX1 expression in human colon cancer surgical specimens. Immunohistochemical analysis of a comprehensive set of tissue microarrays comprising over 1,200 formalin-fixed, paraffin-embedded tissue cores from human epithelial tumors and inflammatory disease confirmed that NOX1 is overexpressed in human colon and small intestinal adenocarcinomas, as well as adenomatous polyps, compared to adjacent, uninvolved intestinal mucosae. In contradistinction to prior studies, we did not find evidence of NOX1 overexpression at the protein level in tumors versus histologically normal tissues in prostate, lung, ovarian, or breast carcinomas. This study constitutes the most comprehensive histopathological characterization of NOX1 to date in cellular models of colon cancer and in normal and malignant human tissues using a thoroughly evaluated monoclonal antibody. It also further establishes NOX1 as a clinically relevant therapeutic target in colorectal and small intestinal cancer.

IL-4 and IL-17A Cooperatively Promote Hydrogen Peroxide Production, Oxidative DNA Damage, and Upregulation of Dual Oxidase 2 in Human Colon and Pancreatic Cancer Cells

Dual oxidase 2 (DUOX2) generates H₂O₂ that plays a critical role in both host defense and chronic inflammation. Previously, we demonstrated that the proinflammatory mediators IFN-γ and LPS enhance expression of DUOX2 and its maturation factor DUOXA2 through STAT1- and NF-κB‒mediated signaling in human pancreatic cancer cells. Using a panel of colon and pancreatic cancer cell lines, we now report the induction of DUOX2/DUOXA2 mRNA and protein expression by the T_H2 cytokine IL-4. IL-4 activated STAT6 signaling that, when silenced, significantly decreased induction of DUOX2. Furthermore, the T_H17 cytokine IL-17A combined synergistically with IL-4 to increase DUOX2 expression in both colon and pancreatic cancer cells mediated, at least in part, by signaling through NF-κB. The upregulation of DUOX2 was associated with a significant increase in the production of extracellular H₂O₂ and DNA damage-as indicated by the accumulation of 8-oxo-dG and γH2AX-which was suppressed by the NADPH oxidase inhibitor diphenylene iodonium and a DUOX2-specific small interfering RNA. The clinical relevance of these experiments is suggested by immunohistochemical, microarray, and quantitative RT-PCR studies of human colon and pancreatic tumors demonstrating significantly higher DUOX2, IL-4R, and IL-17RA expression in tumors than in adjacent normal tissues; in pancreatic adenocarcinoma, increased DUOX2 expression is adversely associated with overall patient survival. These data suggest a functional association between DUOX2-mediated H₂O₂ production and induced DNA damage in gastrointestinal malignancies.

Modulation of selenium-dependent glutathione peroxidase activity enhances doxorubicin-induced apoptosis, tumour cell killing and hydroxyl radical production in human NCI/ADR-RES cancer cells despite high-level P-glycoprotein expression

To define the role of glutathione peroxidase (GPx) in modulating the oxygen radical-related cytotoxicity of doxorubicin and H₂O₂ in cells that overexpress P-glycoprotein (Pgp), the GPx activity of NCI/ADR-RES cancer cells was altered by growth in 0.5% serum with (MR-30 subline) or without (MR-0 subline) selenium supplementation. GPx activity increased from 2.2 nmol/min/mg (MR-0) to 22.5 nmol/min/mg (MR-30) when cells were grown in 30-nM selenium, p < .01; the activities of other antioxidant enzymes were unchanged by selenium. By reverse transcriptase polymerase chain reaction, MR-30 and MR-0 cells expressed similar levels of the MDR1, GPx-1, BCL2 and TOP2A mRNA. The IC₅₀ concentration for H₂O₂ in MR-0 cells was 10-fold lower than in the MR-30 subline, p < .01. Despite identical anthracycline accumulation and efflux in these two lines that expressed equivalent levels of Pgp, the doxorubicin IC₅₀ decreased fivefold in MR-0 versus MR-30 cells, p < .01. Log-linear tumour cell killing by doxorubicin was observed only in selenium-deficient MR-0 cells. Doxorubicin exposure also produced substantially more apoptosis in MR-0 than MR-30 cells; this was not related to the presence of selenium per se. MR-0 cells generated ≈5-times more methane from dimethyl sulfoxide (a measure of reactive oxygen metabolism) than MR-30 cells in the presence of equimolar doxorubicin concentrations (p < .05). These studies suggest that GPx-mediated detoxification of peroxides can modulate the antitumor activity of doxorubicin in the presence of high levels of Pgp.

Abstract 514: DUOX2-related H2O2 production contributes to pro-inflammatory cytokine-related DNA damage and tumor cell growth in models of pancreatic ductal adenocarcinoma

Chronic inflammation is an important risk factor for the development of pancreatic ductal adenocarcinoma (PDAC). Dual oxidase 2 (DUOX2), one of the seven NADPH oxidase (NOX) family members, by generating extracellular H2O2, is intimately involved in both host defense and chronic inflammation in the gastrointestinal tract. Previously, we demonstrated that short (24 h) exposures of several human pancreatic cancer cell lines to pro-inflammatory cytokines (IFN-γ, IL-4/IL-13, IL-17A) can effectively enhance expression of DUOX2 and its maturation factor DUOXA2. To better mimic chronic inflammation in vivo, a panel of human PDAC cell lines was exposed to the TH2 cytokine IL-4 (50ng/ml) for longer times (7 days); and the effect of cytokine treatment on Stat6 activation and DUOX2 mRNA and protein expression was explored. In BxPC-3 and AsPC-1 cell lines, prolonged IL-4 stimulation results in a sustained activation of Stat6, dramatic induction of DUOX2 mRNA and protein expression, a 3-5-fold increase in extracellular H2O2 production compared to solvent-treated cells, and–most importantly–a robust DNA double strand break (DSB) response indicated by elevated levels of γH2AX. In marked contrast, for two JAK-Stat6 signaling defective PDAC lines, PANC-1 and CFPAC-1, no enhancement of DUOX2 expression with concomitant DSBs was observed under the same conditions. Moreover, when the anti-inflammatory drug dexamethasone (Dex) was co-administered with IL-4 (for 48h), cytokine-related DUOX2 induction and DNA damage in BxPC-3 and AsPC-1 cells was significantly diminished. Furthermore, in the KPC GEMM of PDAC, RT-PCR and immunohistochemistry revealed that DUOX2 mRNA and protein expression in pancreatic tumor tissues were significantly increased compared to adjacent normal tissues and were associated with areas of chronic inflammation. Finally, xenografts established with BxPC-3 cell clones in which DUOX2 mRNA was silenced by stable expression of DUOX2-specific shRNAs demonstrated severely delayed growth in vivo compared to clones stably expressing scrambled shRNAs. These studies, coupled with our previous data demonstrating elevated DUOX protein expression in pancreatitis, pancreatic intra-epithelial neoplasia (PanIN), and frank pancreatic cancers in humans, suggest that ROS- derived from cytokine-mediated DUOX2 up-regulation may initiate and promote pancreatic cancer progression through ROS-induced DNA damage.

Citation Format: Yongzhong Wu, Jiamo Lu, Smitha Antony, Jennifer L. Meitzler, Agnes Juhasz, Guojian Jiang, Iris Dahan, James H. Doroshow. DUOX2-related H2O2 production contributes to pro-inflammatory cytokine-related DNA damage and tumor cell growth in models of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 514.

Abstract 876: CD40-induced growth inhibition of Burkitt lymphoma: A possible role for NADPH oxidase by upregulation of p67phox

CD40 stimulation together with IL4 has been shown to promote growth of normal B cells in vitro. In contrast to this, CD40 stimulation in several B cell lymphoma cell lines has been demonstrated to be growth inhibitory. Though the mechanism is not completely known, CD40-stimulated cells exhibit increased levels of reactive oxygen species (ROS). In B lymphocytes, a major source of ROS production is the NADPH oxidase (NOX) that is comprised of a membrane-bound Nox2 catalytic subunit and four cytosolic regulatory components, with the p67phox cytosolic protein being the activator factor. Upon stimulation, by either cross linking of the B-cell receptor or following treatment with PMA, the active NADPH oxidase generates superoxide. We have investigated the role of NADPH oxidase in CD40-mediated growth inhibition in Burkitt lymphoma (BL) cells. For this study, we first evaluated the effect of CD40 stimulation on the expression of Nox2 and p67phox in BL cells that demonstrate different levels of endogenous Nox2 and p67phox. Accordingly, Daudi and Raji cell lines, with endogenously high Nox2 and low p67phox, NAMALWA cells which have high Nox2 and no p67phox expression, and Ramos cells that contain no Nox2 or p67phox were analyzed. Treatment with anti-CD40 or CD40 ligand (CD40L) for 24 h induced up-regulation of p67phox in Daudi, Ramos, and NAMALWA cells, but not in the Raji line. No significant change in the expression of Nox2 was observed. Additionally, Daudi, Ramos and NAMALWA cells showed higher production of ROS after CD40 stimulation and activation with anti-IgM or PMA, in a chemiluminescence assay. To determine whether the change in ROS level was related to the upregulation of p67phox, Daudi cells that express either stable p67phox shRNA or control shRNA were generated. Treatment with CD40L for 24 h demonstrated significant ROS production only in control shRNA and not in the p67shRNA cells, confirming that the ROS production is NOX2-p67phox mediated. This enhanced ROS production was observed following treatment with CD40L alone and was enhanced further in conjunction with anti-IgM or PMA. However, cells with the p67phox shRNA showed detectable level of ROS only after activation with anti IgM, albeit to much lower levels than the control. Co-treatment of Daudi cells with anti-CD40 or CD40L and IL4 further increased the expression of p67phox. Although the basal level of ROS in the cells was unchanged upon co-treatment, the ROS generated following stimulation with anti-IgM or PMA was significantly enhanced. Preliminary MTT studies confirmed the growth inhibition of CD40-stimulated Daudi cells but not of Raji cells, suggesting a role for p67phox-dependent, ROS-related inhibition of lymphoma cell proliferation. Experiments are currently ongoing to delineate further the role of CD40 stimulation and Nox2-p67phox mediated ROS in affecting the growth of Burkitt lymphomas and signaling pathways downstream of CD40.

Citation Format: Mazal Iris Dahan, Smitha Antony, Agnes Juhasz, Guojian Jiang, Mariam Konate, Jiamo Lu, Jennifer Meitzler, YongZhong Wu, Krishnendu Roy, James H. Doroshow. CD40-induced growth inhibition of Burkitt lymphoma: A possible role for NADPH oxidase by upregulation of p67phox [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 876.

NADPH oxidase 5 (NOX5)-induced reactive oxygen signaling modulates normoxic HIF-1α and p27Kip1 expression in malignant melanoma and other human tumors

NADPH oxidase 5 (NOX5) generated reactive oxygen species (ROS) have been implicated in signaling cascades that regulate cancer cell proliferation. To evaluate and validate NOX5 expression in human tumors, we screened a broad range of tissue microarrays (TMAs), and report substantial overexpression of NOX5 in malignant melanoma and cancers of the prostate, breast, and ovary. In human UACC‐257 melanoma cells that possesses high levels of functional endogenous NOX5, overexpression of NOX5 resulted in enhanced cell growth, increased numbers of BrdU positive cells, and increased γ‐H2AX levels. Additionally, NOX5‐overexpressing (stable and inducible) UACC‐257 cells demonstrated increased normoxic HIF‐1α expression and decreased p27^Kip1 expression. Similarly, increased normoxic HIF‐1α expression and decreased p27^Kip1 expression were observed in stable NOX5‐overexpressing clones of KARPAS 299 human lymphoma cells and in the human prostate cancer cell line, PC‐3. Conversely, knockdown of endogenous NOX5 in UACC‐257 cells resulted in decreased cell growth, decreased HIF‐1α expression, and increased p27^Kip1 expression. Likewise, in an additional human melanoma cell line, WM852, and in PC‐3 cells, transient knockdown of endogenous NOX5 resulted in increased p27^Kip1 and decreased HIF‐1α expression. Knockdown of endogenous NOX5 in UACC‐257 cells resulted in decreased Akt and GSK3β phosphorylation, signaling pathways known to modulate p27^Kip1 levels. In summary, our findings suggest that NOX5 expression in human UACC‐257 melanoma cells could contribute to cell proliferation due, in part, to the generation of high local concentrations of extracellular ROS that modulate multiple pathways that regulate HIF‐1α and networks that signal through Akt/GSK3β/p27^Kip1.

Characterization of potent and selective iodonium-class inhibitors of NADPH oxidases

The NADPH oxidases (NOXs) play a recognized role in the development and progression of inflammation-associated disorders, as well as cancer. To date, several NOX inhibitors have been developed, through either high throughput screening or targeted disruption of NOX interaction partners, although only a few have reached clinical trials. To improve the efficacy and bioavailability of the iodonium class NOX inhibitor diphenylene iodonium (DPI), we synthesized 36 analogs of DPI, focusing on improved solubility and functionalization. The inhibitory activity of the analogs was interrogated through cell viability and clonogenic studies with a colon cancer cell line (HT-29) that depends on NOX for its proliferative potential. Lack of altered cellular respiration at relevant iodonium analog concentrations was also demonstrated. Additionally, inhibition of ROS generation was evaluated with a luminescence assay for superoxide, or by Amplex Red® assay for H₂O₂ production, in cell models expressing specific NOX isoforms. DPI and four analogs (NSCs 740104, 751140, 734428, 737392) strongly inhibited HT-29 cell growth and ROS production with nanomolar potency in a concentration-dependent manner. NSC 737392 and 734428, which both feature nitro functional groups at the meta position, had >10-fold higher activity against ROS production by cells that overexpress dual oxidase 2 (DUOX2) than the other compounds examined (IC₅₀≈200-400nM). Based on these results, we synthesized and tested NSC 780521 with optimized potency against DUOX2. Iodonium analogs with anticancer activity, including the first generation of targeted agents with improved specificity against DUOX2, may provide a novel therapeutic approach to NOX-driven tumors.

Decoding NADPH oxidase 4 expression in human tumors

NADPH oxidase 4 (NOX4) is a redox active, membrane-associated protein that contributes to genomic instability, redox signaling, and radiation sensitivity in human cancers based on its capacity to generate H₂O₂ constitutively. Most studies of NOX4 in malignancy have focused on the evaluation of a small number of tumor cell lines and not on human tumor specimens themselves; furthermore, these studies have often employed immunological tools that have not been well characterized. To determine the prevalence of NOX4 expression across a broad range of solid tumors, we developed a novel monoclonal antibody that recognizes a specific extracellular region of the human NOX4 protein, and that does not cross-react with any of the other six members of the NOX gene family. Evaluation of 20 sets of epithelial tumors revealed, for the first time, high levels of NOX4 expression in carcinomas of the head and neck (15/19 patients), esophagus (12/18 patients), bladder (10/19 patients), ovary (6/17 patients), and prostate (7/19 patients), as well as malignant melanoma (7/15 patients) when these tumors were compared to histologically-uninvolved specimens from the same organs. Detection of NOX4 protein upregulation by low levels of TGF-β1 demonstrated the sensitivity of this new probe; and immunofluorescence experiments found that high levels of endogenous NOX4 expression in ovarian cancer cells were only demonstrable associated with perinuclear membranes. These studies suggest that NOX4 expression is upregulated, compared to normal tissues, in a well-defined, and specific group of human carcinomas, and that its expression is localized on intracellular membranes in a fashion that could modulate oxidative DNA damage.

NADPH oxidase 1 supports proliferation of colon cancer cells by modulating reactive oxygen species-dependent signal transduction

Reactive oxygen species (ROS) play a critical role in cell signaling and proliferation. NADPH oxidase 1 (NOX1), a membrane-bound flavin dehydrogenase that generates O₂^˙̄, is highly expressed in colon cancer. To investigate the role that NOX1 plays in colon cancer growth, we used shRNA to decrease NOX1 expression stably in HT-29 human colon cancer cells. The 80–90% decrease in NOX1 expression achieved by RNAi produced a significant decline in ROS production and a G₁/S block that translated into a 2–3-fold increase in tumor cell doubling time without increased apoptosis. The block at the G₁/S checkpoint was associated with a significant decrease in cyclin D₁ expression and profound inhibition of mitogen-activated protein kinase (MAPK) signaling. Decreased steady-state MAPK phosphorylation occurred concomitant with a significant increase in protein phosphatase activity for two colon cancer cell lines in which NOX1 expression was knocked down by RNAi. Diminished NOX1 expression also contributed to decreased growth, blood vessel density, and VEGF and hypoxia-inducible factor 1α (HIF-1α) expression in HT-29 xenografts initiated from NOX1 knockdown cells. Microarray analysis, supplemented by real-time PCR and Western blotting, revealed that the expression of critical regulators of cell proliferation and angiogenesis, including c-MYC, c-MYB, and VEGF, were down-regulated in association with a decline in hypoxic HIF-1α protein expression downstream of silenced NOX1 in both colon cancer cell lines and xenografts. These studies suggest a role for NOX1 in maintaining the proliferative phenotype of some colon cancers and the potential of NOX1 as a therapeutic target in this disease.

Kinetics of Exhaled Carbon Monoxide After Water-pipe Smoking Indoors and Outdoors

BACKGROUND

Despite accumulating evidence about its adverse health effects, water-pipe tobacco smoking has become very popular among youth. The aim of this study was to compare smoke exposure and the kinetics of exhaled carbon monoxide (eCO) between water-pipe and cigarette smokers under different conditions.

METHODS

Using a cross-over study design, changes in eCO and urinary cotinine levels were measured in a cohort of 32 healthy university students after sessions of water-pipe smoking indoors and outdoors. An indoor cigarette smoking session with equal amounts of tobacco was conducted for reference purposes. Both active and passive smokers participated in all sessions.

RESULTS

In indoor sessions, we found that among active participants, eCO levels were approximately 7.5-fold higher in water-pipe users than cigarette smokers. eCO levels remained significantly elevated even 10 h after discontinuing water-pipe smoking. Notably, eCO levels in passive water-pipe smokers were in the same range as in active cigarette smokers. Compared with indoor sessions, eCO levels in active water-pipe users were reduced in outdoor environments. Nonetheless, levels were still higher in these subjects than those in active cigarette smokers measured in indoor sessions. Urinary cotinine levels were comparable in active water-pipe and cigarette smokers.

CONCLUSIONS

Our results suggest that water-pipe smoking is associated with significantly higher toxicant exposure than cigarette smoking even in outdoor environments. Furthermore, even passive, indoor water-pipe smoke exposure may have significant health hazards compared with those of active cigarette smoking.

The winds from HL Tau

Outflowing motions, whether a wind launched from the disc, a jet launched from the protostar, or the entrained molecular outflow, appear to be a ubiquitous feature of star formation. These outwards motions have a number of root causes, and how they manifest is intricately linked to their environment as well as the process of star formation itself. Using the Atacama Large Millimeter/submillimeter Array (ALMA) Science Verification data of HL Tau, we investigate the high-velocity molecular gas being removed from the system as a result of the star formation process. We aim to place these motions in context with the optically detected jet, and the disc. With these high-resolution (∼1 arcsec) ALMA observations of CO (J=1-0), we quantify the outwards motions of the molecular gas. We find evidence for a bipolar outwards flow, with an opening angle, as measured in the redshifted lobe, starting off at 90°, and narrowing to 60° further from the disc, likely because of magnetic collimation. Its outwards velocity, corrected for inclination angle is of the order of 2.4 km s^-1.

Abstract 1456: Dexamethasone suppresses cytokine-induced dual oxidase 2 (Duox2) and VEGF-A expression in human pancreatic cancer cells in vitro and pancreatic cancer growth in xenografts

Chronic pancreatic inflammation is strongly associated with pancreatic cancer. We previously demonstrated that inflammatory cytokines interact to produce a Duox2 (one of 7 members of the NADPH Oxidase family)-dependent, reactive oxygen species (ROS)-related, pro-oxidant milieu that could increase the pathologic potential of pancreatic inflammation, enhancing malignant transformation. Furthermore, we have shown that Duox2 expression is upregulated in patients with chronic pancreatitis as well as pancreatic ductal adenocarcinoma (PDAC). Dexamethasone (Dex) has been reported to inhibit PDAC invasiveness, the formation of pancreatic intraepithelial neoplasia in genetically-engineered mouse models of pancreatic cancer, as well as epithelial to mesenchymal transition, and local tumor recurrence and metastasis in vivo. Using cultured human pancreatic cancer cell lines, we found that in a dose- and time-dependent fashion Dex inhibited cytokine (IFN-γ/LPS, IL-4, and IL-17)-mediated up-regulation of Duox2 and VEGF-A expression in several human pancreatic cancer cell lines, including BxPC-3, ASPC-1, and CFPAC-1. The effects of Dex were abolished by pre-treatment with the Dex antagonist RU-486. As expected, we did not observe anti-proliferative effects of Dex on PDAC cells in vitro. However, Dex strongly repressed Duox2 mRNA and protein expression as well as the growth of xenografts initiated from BxPC-3 cells; in contrast, for the MIA-Paca line that is unresponsive to cytokines in culture, Dex produced no effect on Duox2 expression and tumor growth when these cells were grown as xenografts. Examination of the human Duox2 promotor in silico revealed a putative negative glucocorticoid receptor (GR) binding element. Western analysis, using nuclear extracts from pancreatic cancer cells treated with Dex, revealed that both activated glucocorticoid receptor and certain co-repressors, such as NCOR-1/2 and histone deacetylases (HDAC1, 2, and 3) exist in human pancreatic cancer cell nuclei. Our ongoing experiments are focused on understanding the molecular mechanism of Dex-mediated Duox2 repression both in vitro and in vivo. In summary, these studies suggest that cytokine-related oxidant stress, generated by Duox2, could play a role in the progression of pancreatic cancer.

Citation Format: Yongzhong Wu, Smitha Antony, Jennifer L. Meitzler, Jiamo Lu, Agnes Juhasz, Guojian Jiang, Krishnendu Roy, James H. Doroshow. Dexamethasone suppresses cytokine-induced dual oxidase 2 (Duox2) and VEGF-A expression in human pancreatic cancer cells in vitro and pancreatic cancer growth in xenografts. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1456.

Abstract 2809: ROS signaling by NADPH oxidase 5 (Nox5) modulates proliferation of human melanoma UACC-257 cells and prolongs growth in the absence of serum or growth factors

Reactive oxygen species (ROS) produced by the NADPH oxidase (Noxs) homologs participate in signaling cascades regulating proliferation. Recently, we have reported substantial overexpression of Nox5 in several human cancers including those of prostate, ovary and melanomas. Despite being upregulated in many human cancers and implicated in promoting cell proliferation, the molecular mechanisms modulated by Nox5 are poorly understood. In this study, the functional significance of Nox5 was assessed in human UACC-257 and WM-852 melanoma cells by generating Nox5-overexpressing and knockdown cells. Stable overexpression of Nox5 in UACC-257 cells resulted in enhanced cell growth, increased BrdU positive cells and decreased protein tyrosine phosphatase activity. Additionally, these cells had increased normoxic Hif-1α expression and decreased p27Kip1 expression. Conversely, knockdown of endogenous Nox5 in UACC-257 cells resulted in decreased cell growth, decreased BrdU positive cells, decreased Hif-1α expression and increased p27Kip1 expression. Likewise, in human WM-852 melanoma cells, transient overexpression of Nox5 decreased p27Kip1 expression and knockdown of endogenous Nox5 resulted in increased p27Kip1 and gamma-H2AX expression with decreased cell growth. Cadherin switch, loss of E-cadherin expression and upregulation of N-cadherin was observed in UACC-257 Nox5 overexpressing cells indicative of an invasive phenotype; conversely, an upregulation of E-cadherin expression in Nox5 knockdown cells was noted. Cell invasion assay through matrigel-coated membranes also demonstrated enhanced invasion by Nox5 overexpressing cells. Additionally, 3D cultures of Nox5 overexpressing UACC-257 cells exhibit an amoeboid morphology compared to that of the Nox5 knockdown cells that were mesenchymal, suggestive of an amoeboid - mesenchymal (AMT) transition. Strikingly, UACC-257 cells that overexpress Nox5 were able to proliferate in serum-free conditions for over a month. In summary, our findings suggest that ROS signaling by Nox5 in human melanoma could modulate multiple signaling networks that regulate Hif-1α and p27Kip1 expression, contributing in part, to cell proliferation and the ability to grow in the absence of serum or growth factors.

Citation Format: Smitha Antony, Yongzhong Wu, Diana C. Haines, Guojian Jiang, Jennifer L. Meitzler, Agnes Juhasz, Jiamo Lu, Krishnendu K. Roy, James H. Doroshow. ROS signaling by NADPH oxidase 5 (Nox5) modulates proliferation of human melanoma UACC-257 cells and prolongs growth in the absence of serum or growth factors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2809.

Abstract 4750: Development of potent NADPH oxidase inhibitors with significant activity against colon cancer

The NADPH oxidase (NOX) gene family (NOX1-5 and Duox1/2) plays an important role in host defense and the development of inflammation-induced carcinogenesis. We recently found that two iodonium-class NOX inhibitors, diphenyleneiodonium (DPI) and di-2-thienyliodonium (DTI), block NOX-dependent reactive oxygen species (ROS) formation, NOX1 mRNA expression, and growth of human colon cancer cells in vitro and in vivo (Free Rad. Biol. Med. 57: 162, 2013). To improve the efficacy and bioavailability of DPI and DTI, we synthesized 48 new analogs of these compounds (21 DPI analogs, 12 DTI analogs, and 15 DPI and/or DTI hybrids; structures to be presented at the meeting) and prioritized the agents for further study based on inhibition of: HT-29 growth (MTT and clonogenic assay), ROS generation (by chemiluminescence and flow cytometry), and NOX1 mRNA expression (by qRT-PCR). The compounds were also characterized for lack of altered mitochondrial ROS production, and inhibitory effects on ROS generated by cell-based assays specific for NOX1, NOX2, NOX4, NOX5, and Duox2. DPI and five DPI analogs, NSCs 740104, 734428, 742837, 751140, 737392, strongly inhibited HT-29 cell growth in a dose dependant manner (IC50's after 48 hr drug exposure of 300, 50, 74, 87, 148, and 202 nM, respectively). Treatment for 24 hr with 10 nM DPI, 740104, 734428, or 751140, or with 100 nM 737392 significantly decreased ROS production in HT-29 cells. In addition, 60% or greater inhibition of NOX1 mRNA expression was observed following treatment with 250 nM 740104 and 734428 for 4 hr; 751140 and DPI for 24 hr; and 737392 for 48 hr. Analog 742837 demonstrated no significant inhibition of either ROS production or NOX1 expression in HT-29 cells; it was not analyzed further. Growth inhibitory properties of 734958, a DTI analog, were similar to the parent molecule. To evaluate compound specificity, a luminescence assay for O2•¯ was used with: HEK293 cells expressing all components of the NOX1 complex; fully differentiated HL-60 cells expressing active NOX2; and UACC257 melanoma cells that exclusively express active NOX5. H2O2 was measured by Amplex Red assay to determine NOX4 or Duox2 activity in fully reconstituted HEK293 cells. DPI, 734428, 740104, 737392, or 751140 exposure for 30 min inhibited NOX1, 2, 4, and 5 with low nM IC50's; analogs 740104, 734428, and 751140 were more potent inhibitors of NOX1, 2, and 4, respectively, than DPI; each was broadly active against these NOX isoforms. The DTI analog 734958 was more potent than its parent molecule. NSC737392 and 734428 were &gt;10-fold more active than the other compounds examined against Duox2 (200-400 nM IC50's). In summary, we developed novel iodonium analogs with anticancer activity that possess enhanced potency against human NOX species, including the first agents with specificity against Duox2. These tool compounds will be evaluated in vivo for their therapeutic and anti-inflammatory activities in NOX-containing tumor xenograft models.

Citation Format: Jiamo Lu, Prabhakar Risbood, Charles T. Kane, Md Tafazzal Hossain, Yongzhong Wu, Smitha Antony, Jennifer L. Meitzler, Agnes Juhasz, Han Liu, Guojian Jiang, Krishnendu Roy, James H. Doroshow. Development of potent NADPH oxidase inhibitors with significant activity against colon cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4750. doi:10.1158/1538-7445.AM2014-4750

NADPH oxidases: a perspective on reactive oxygen species production in tumor biology

SIGNIFICANCE

Reactive oxygen species (ROS) promote genomic instability, altered signal transduction, and an environment that can sustain tumor formation and growth. The NOX family of NADPH oxidases, membrane-bound epithelial superoxide and hydrogen peroxide producers, plays a critical role in the maintenance of immune function, cell growth, and apoptosis. The impact of NOX enzymes in carcinogenesis is currently being defined and may directly link chronic inflammation and NOX ROS-mediated tumor formation.

RECENT ADVANCES

Increased interest in the function of NOX enzymes in tumor biology has spurred a surge of investigative effort to understand the variability of NOX expression levels in tumors and the effect of NOX activity on tumor cell proliferation. These initial efforts have demonstrated a wide variance in NOX distribution and expression levels across numerous cancers as well as in common tumor cell lines, suggesting that much remains to be discovered about the unique role of NOX-related ROS production within each system. Progression from in vitro cell line studies toward in vivo tumor tissue screening and xenograft models has begun to provide evidence supporting the importance of NOX expression in carcinogenesis.

CRITICAL ISSUES

A lack of universally available, isoform-specific antibodies and animal tumor models of inducible knockout or over-expression of NOX isoforms has hindered progress toward the completion of in vivo studies.

FUTURE DIRECTIONS

In vivo validation experiments and the use of large, existing gene expression data sets should help define the best model systems for studying the NOX homologues in the context of cancer.

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.

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.

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.

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.