Inflammatory events during murine squamous cell carcinoma development
© Gasparoto et al.; licensee BioMed Central Ltd. 2012
Received: 12 March 2012
Accepted: 6 November 2012
Published: 23 November 2012
Squamous cell carcinoma (SCC) is one of the most common human cancers worldwide. In SCC, tumour development is accompanied by an immune response that leads to massive tumour infiltration by inflammatory cells, and consequently, local and systemic production of cytokines, chemokines and other mediators. Studies in both humans and animal models indicate that imbalances in these inflammatory mediators are associated with cancer development.
We used a multistage model of SCC to examine the involvement of elastase (ELA), myeloperoxidase (MPO), nitric oxide (NO), cytokines (IL-6, IL-10, IL-13, IL-17, TGF-β and TNF-α), and neutrophils and macrophages in tumour development. ELA and MPO activity and NO, IL-10, IL −17, TNF-α and TGF-β levels were increased in the precancerous microenvironment.
ELA and MPO activity and NO, IL-10, IL −17, TNF-α and TGF-β levels were increased in the precancerous microenvironment. Significantly higher levels of IL-6 and lower levels of IL-10 were detected at 4 weeks following 7,12-Dimethylbenz(a)anthracene (DMBA) treatment. Similar levels of IL-13 were detected in the precancerous microenvironment compared with control tissue. We identified significant increases in the number of GR-1+ neutrophils and F4/80+/GR-1- infiltrating cells in tissues at 4 and 8 weeks following treatment and a higher percentage of tumour-associated macrophages (TAM) expressing both GR-1 and F4/80, an activated phenotype, at 16 weeks. We found a significant correlation between levels of IL-10, IL-17, ELA, and activated TAMs and the lesions. Additionally, neutrophil infiltrate was positively correlated with MPO and NO levels in the lesions.
Our results indicate an imbalance of inflammatory mediators in precancerous SCC caused by neutrophils and macrophages and culminating in pro-tumour local tissue alterations.
KeywordsElastase Nitric oxide Myeloperoxidase Inflammatory cells Cytokines
Inflammatory responses play decisive roles in different stages of tumour development, including initiation, promotion, progression, invasion, and metastasis. The tumour microenvironment, which is orchestrated by inflammatory cells, affects malignant cells through the production of cytokines, chemokines, growth factors, prostaglandins, reactive oxygen species (ROS) and nitric oxide (NO)[1–5]. Sub-lethal levels of ROS and NO, which are produced by activated neutrophils and macrophages, drive cancer development by inducing DNA damage[6–8]. They also stimulate cancer cell proliferation, assisting tumour establishment[5, 9]. Myeloperoxidase (MPO), which is abundantly expressed in neutrophils and to a lesser extent in monocytes and certain type of macrophages, has been strongly correlated with different types of cancer progression due to its role in ROS generation[2, 9, 11]. Additionally, the proteolytic enzyme elastase (ELA) is also involved with carcinogenesis and metastasis through degradation of the extracellular matrix, facilitating cancer invasion[12, 13].
Squamous cell carcinoma (SCC) is one of the most common cancers in humans and typically arises from mutated ectodermal or endodermal cells lining body cavities. While SCC can occur in a large number of tissues, cells in the skin are frequently associated with cellular abnormalities in the basal layer of the epidermis resulting from UV-damaged keratinocytes[14–16]. Although immunosuppression is currently considered to be a risk factor for SCC, inflammation is involved in SCC establishment, and UV light has been demonstrated to increase inflammatory infiltrates, which enhances skin tumour growth[17, 18]. In this manner, CXCL8 has been suggested as an earlier biomarker for SCC because this chemokine, one of the most important neutrophil chemotactic and activating factors, is related to angiogenesis, tumour growth and metastasis. However, other cytokines and chemokines that coordinate leukocyte migration to inflammatory sites and cellular trafficking through the lymph nodes and the spleen have been associated with SCC development[20, 21]. The two-stage 7,12-dimethylbenz(a)-anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA) skin carcinogenesis model, which triggers the initiation and promotion steps, respectively, has been commonly used to mimic squamous cell carcinoma, allowing for the investigation of several aspects of SCC[22, 23]. TPA/PMA tumour promotion is based on protein kinase C (PKC) activation culminating in the release of reactive oxygen species (ROS)[24, 25].
Because inflammatory events have been implicated in carcinogenesis and neutrophil infiltration is correlated with some types of cancer metastasis[26, 27], we used a multistage model of SCC to examine the involvement of ELA, MPO, NO, cytokines and inflammatory cells in tumour development.
Eight-week-old female BALB/c mice were purchased from the Bauru School of Dentistry, University of São Paulo. Each mouse was housed in an isolated cage. Food and water were provided ad libitum. The mice were maintained on a 12-h light/12-h dark photocycle in a controlled temperature environment and were quarantined for a minimum of 1 week before treatment. Groups of mice were randomly euthanised between 4 weeks and 16 weeks following 7,12-dimethylbenz-anthracene (DMBA) (Sigma-Aldrich®, St. Louis, MO, USA) application. A total of 36 mice were used in the study. All animal experiments were approved by the Animal Research Ethics Committee of the Bauru School of Dentistry, University of São Paulo.
DMBA/PMA-induced skin carcinogenesis initiation-promotion experiments
The experimental group received DMBA and 12-O-tetradecanoyl-phorbol-13-acetate (TPA) (Sigma-Aldrich®) as follows. Eight-week-old female mice were divided into 3 groups of three mice (at 4th, 8th and 16th weeks) each and were topically treated with four doses of DMBA (25 μg in 200 μl of acetone) and biweekly doses of TPA (200 μl of a 10–4 M solution in acetone) for 16 weeks. The experiment was performed 3 times. Papilloma and carcinoma development were monitored every three days throughout the experiment. Papillomas were characterised by folded epidermal hyperplasia protruding from the skin surface, and carcinomas were characterised as endophytic tumours presenting as plaques with an ulcerated surface. Experimental animals were cared for in accordance with institutional guidelines. Untreated mice were used as the control group. Samples were collected at different time points after initiation and were processed as described below. Lesions were initially identified macroscopically and subsequently identified through histological diagnosis.
Measurement of tumour growth
Skin tumours were measured using a precision calliper allowing discrimination to size modifications >0.1 mm. Tumour volumes were measured the first day of treatment and every week until the day that they were humanely killed and the lesions were measured according to followed: volume = 0.4 ab2, where a and b are the larger and smaller diameters, respectively.
Tissue samples were collected from tumour sites and fixed with 10% (v/v) formalin for 6 hours at room temperature. The tissues were subsequently dehydrated in ethyl alcohol followed by washes in xylol and were then embedded in paraffin. Each sample was sectioned into 5- to 7-μm-thick slices that were dried onto slides and stained with hematoxylin and eosin.
Isolation of leukocytes
To characterise the leukocytes present at the tumour site, biopsies of skin lesions from mice were collected and incubated for 1 h at 37°C in RPMI 1640 medium containing 50 μg/mL of a collagenase CI enzyme blend (Boehringer Ingelheim Chemicals, Normandy Drive Petersburg, VA, USA). The tissues were subsequently dissociated for 4 min in RPMI 1640 (GIBCO®, Life Technologies, Staley Road Grand Island, NY, USA) with 10% bovine foetal serum (GIBCO®, Life Technologies) and 0.05% DNase (Sigma-Aldrich®) using a Medimachine (BD Biosciences, Qume Drive San Jose, CA, USA) cytometry sample preparation system, according to the manufacturer’s instructions. The tissue homogenates were filtered using a 30-μm cell strainer (Falcon; BD Biosciences). Leukocyte viability was evaluated by Trypan blue exclusion, and these cells were subsequently used for cell activation and immunolabelling assays.
Antibodies (Abs) and flow cytometry analysis
For immunostaining, PE- and FITC-conjugated Abs directed against CD11b (17A2), LY6G/GR-1+ (H129.19), F4/80 (6F12) and the respective goat and rat isotype controls were used (BD Biosciences). Intracellular IL-17 (BD Biosciences) in leukocytes obtained from lesions and lymph nodes was detected using Cytofix/Cytoperm and Perm/Wash buffer from BD Biosciences, according to the manufacturer’s instructions. Briefly, the cells were labelled with Abs directed against the cell surface antigens. Following surface staining, the cells were fixed, permeabilised, and stained with PE-labelled anti-mouse IL-17 (MACS Miltenyi Biotech, Miltenyi Biotec GmbH, Bergisch Gladbach, Germany) or the isotype control. The samples were acquired on a FACSort flow cytometer, and the data were analysed using CellQuest software (BD Biosciences).
Immunofluorescence analysis and confocal microscopy
Slides for double immunofluorescence staining were post-fixed with 4% paraformaldehyde and blocked with protein-block assay diluent (BD Company). After washing with PBS, the slides were incubated with the primary antibody, washed again, and incubated with the appropriate fluorochrome-conjugated (Texas Red or FITC) secondary antibodies. After washing, the slides were mounted using mounting medium with DAPI (Vector Laboratories®, Burlingame, CA, USA) to stain the nucleus and were then analysed by confocal microscopy. Images were captured with a Leica TCS SPE confocal laser system equipped with a 63 oil-immersion plan apochromatic objective (1.3 CS) with differential interference contrast. LAS AF 2.5.1 software was used for image acquisition.
The tumour sample supernatants were obtained by disaggregation through treatment with RPMI 1640 medium containing 0.25% collagenase (Worthington Biochemical Corporation, Lakewood, NJ, USA) and were frozen at −80°C until analysis. The total protein concentration was measured using a Quick StartTM Bradford Protein assay kit (Bio-Rad, CA, USA). TNF-α, IL-6, IL-10 and TGF-β levels in the samples were quantified using a quantitative sandwich enzyme-linked immunosorbent assay (ELISA) that employed commercial capture and biotinylated detection antibodies (BD Pharmingen Corp., San Diego, CA), and the respective recombinant mouse cytokines (diluted in PBS) as standards according to the manufacturer’s instructions. IL-13 and IL-17 levels were determined using an eBioscience kit (eBioscience®, San Diego, CA, USA) according to the manufacturer’s instructions. The concentration of each cytokine was dosed as pg/mL, and the results were normalised and expressed as mg/protein.
Myeloperoxidase (MPO) and elastase (ELA) activities
MPO and ELA activities in the samples were assessed after obtaining tissue supernatants by disaggregation through treatment with RPMI 1640 (Gibco) medium containing 0.25% collagenase (Worthington Biochemical Corporation) as described previously.
Nitric oxide production
To detect NO in lesions or skin samples, nitrite (NO-2) production was measured in the supernatant samples using the Griess method. Briefly, 50 μL of supernatant samples were incubated with an equal volume of Griess reagent at room temperature. The absorbance was measured on a plate scanner (Spectra Max 250; Molecular Devices, Sunnywale, California, USA) at 540 nm. The NO-2 concentration was determined using a standard curve for NaNO2 at a concentration range from 1 to 200 μM.
The results are expressed as the mean ± SD, and statistical analysis was performed using unpaired Student’s t-tests to compare each experimental group with the control group and a one-way ANOVA followed by Tukey’s test to compare all groups (GraphPad software 4). p ≤ 0.05 was considered to indicate statistical significance.
The appearance of chemically induced papillomas is accompanied by increased neutrophil infiltration
Inflammatory mediators levels during the establishment of SCC.
NO levels in the tissue samples were significantly higher after chemical treatment compared to the control group (Figure2B). Interestingly, the highest levels of NO were detected in the 8-week group (1460 ± 215.1μM) (Figure2B), which was also verified by MPO activity (Figure2A).
ELA activity increased as a function of the time of treatment. The 4-week (9.8 ± 2.4 units/mg), 8-week (22.4 ± 17.2 units/mg) and 16-week (54.6 ± 9.9 units/mg) groups all had ELA activities that were significantly higher than that of the control group (2.19±0.2 units/mg) (Figure2C).
Cytokine levels in the tumour microenvironment during the establishment of SCC
In agreement with these data, a significant increase in cytokine levels was detected during SCC development compared with the untreated group (week 0). We verified that the highest levels of the cytokines IL-10, IL-17, TNF-α and TGF-β were present at 16 weeks (Figure3).
Determination of macrophages and neutrophils infiltrating squamous cell carcinoma lesions
We next analysed the inflammatory infiltrates, assessing the presence of neutrophils and macrophages in chemically treated tissues from the mice at 4, 8 and 16 weeks following DMBA treatment (Figure4B-4C). To determine the neutrophil and macrophage phenotypes present in the tissues infiltrates, the percentage of cells expressing GR-1 and F4/80 were evaluated by flow cytometry (Figure4B). Neutrophils, as characterised by a GR-1+/F4/80- phenotype, were increased at 4 (34.6 ± 2.5%) and 8 weeks (55.9 ± 3.2%) compared with 16 weeks (27.3 ± 3.8%). Macrophages were also present at higher percentages in the 4th (47.7 ± 4.9%) and 8th (35.6 ± 3.2%) week compared to the 16th week (24.3 ± 6.1%) (Figure4B). However, macrophages exhibiting an activated phenotype and characterised by expression of both GR-1 and F4/80 were present at a significantly higher concentration at 16 weeks (57.7 ± 0.9%) than at 4 (20.5 ± 5.7%) or 8 weeks (26.5 ± 5.9%) following DMBA/TPA treatment (Figure4B). Representative photomicrographs show immunofluorescence staining for 4 weeks (Figure4C-D), 8 weeks (Figure4E-F) and 16 weeks (Figure4 G-H) following DMBA application.
Correlation between lesions and inflammatory mediators during the chemical-induced squamous cell carcinoma development
Correlation between neutrophils and inflammatory mediators during the chemical-induced squamous cell carcinoma development
Correlation between F4/80 + GR1 + macrophages and inflammatory mediators during chemical-induced squamous cell carcinoma development
Cancer is a complex, multistage process characterised by molecular alterations regulated by both genetic and epigenetic mechanisms. Because DNA lesions and methylation states are influenced by oxidative species catalysed by MPO, it is logical to assume that an association exists between this enzyme and cancer initiation[30–32]. Polymorphisms in the MPO gene promoter region are associated with a reduced risk of cancer[33–35]. Here, we demonstrate the presence of neutrophils and activated macrophages during the development of chemically induced squamous cell carcinoma. This cell infiltration was accompanied by myeloperoxidase and elastase activity and the presence of nitric oxide. Both myeloperoxidase (MPO) and elastase (ELA) are enzymes that are abundantly secreted by activated neutrophils, a mechanism that helps these cells to defend against aggression[10, 36]. MPO dimeric alpha-heme halo peroxidase present in azurophilic granules makes up approximately 5% of the dry weight of the neutrophil. Although MPO is correlated with a better prognosis in different types of tumours such as breast cancer[34, 38–41], the majority of studies have shown an important role for MPO in cancer progression[2, 9, 11, 31]. It was shown that TPA-stimulated mouse neutrophils exhibit DNA damage resulting from hydrogen peroxide-induced breaks. In support of this finding, we found MPO to be significantly more active in chemically treated mice than in control mice, and we found a positive correlation with neutrophil infiltration.
Both MPO and ELA appeared to contribute to tissue and extracellular matrix degradation, enhancing cancer development by destroying natural barriers against metastasis[43, 44]. Several studies have also described elastinolytic enzyme production by human and rodent mammary tumour cells that facilitates their dissemination[10, 45, 46]. ROS-mediated oxidative tissue damage and ROS-mediated upregulation of the gene expression responsible for recruitment of inflammatory cells can both inhibit tumour growth and support the metastatic growth of tumour cells[5, 24, 25].
Although three types of ELA have been characterised in mammals, only neutrophil elastase (NE) is able to degrade insoluble elastin and hydrolyse other extramatrix proteins, including fibronectin, proteoglycans, and type IV collagen[13, 47, 48]. NE has also been shown to increase cancer cell malignancy through mechanisms that are still unclear. We detected high ELA activity at 4 weeks after DMBA/TPA treatment that persisted until 16 weeks and increased as the lesions grew. It is possible that ELA sources such as macrophages, neutrophils, and cancer cells change during chemically induced SCC development. Our data showed that macrophage but not neutrophil infiltration was correlated with ELA activity in the lesions. This result should be further elucidated in the future.
Because our results indicated the involvement of inflammation during chemically induced SCC development, and a key molecular link between inflammation and tumour promotion and progression is the NF-kB signalling pathway, which is activated by many proinflammatory cytokines[49, 50], we analysed cytokine production in the tumour microenvironment. IL-6 was significantly enhanced at 4 weeks after DBMA/TPA treatment, while IL-10 levels were lowest in these samples (Figure4). IL-6 and TNF-α are the major pro-inflammatory cytokines implicated in inflammation-associated carcinogenesis, enhancing tumour cell growth[51, 52]. Because the highest levels of IL-6 occurred at the onset of SCC induction, it is possible that this cytokine plays a role in cancer establishment in our model. IL-6 has also been shown to inhibit the extrinsic and intrinsic apoptotic pathways of skin cells, supporting the hypothesis that it may contribute to tumourigenesis. Although IL-6 has previously been connected with squamous cell carcinoma bone invasion, which occurs during late stages of the disease, the highest concentration of this cytokine was detected at the beginning of DMBA-treatment. TNF-α also has also been proposed to contribute to squamous cell carcinoma tumour initiation and bone invasion by stimulating the production of genotoxic molecules that can lead to DNA damage and mutations, such as NO, which is increased in all treated groups (Figure2B)[56–58]. Levels of IL-13 were also diminished in chemically treated skin after the 4th week (Figure3C). Because IL-13 can negatively regulate anti-tumour immunity modulating NKT cell function, it may cooperate in cancer development.
The dual functions of IL-10 in antitumor immunity and immunoregulation have been recognized for some time. In our study, the low levels of IL-10 detected in tumour initiation phase could be contributed to murine SCC development. IL-10 has been shown to modulate apoptosis and suppress angiogenesis and enhance the production of tumor-toxic molecules (e.g., nitric oxide)[61, 62] and low levels of this cytokine could be favour tumor development. In fact, IL-10 deficient mice were more sensitive to DMBA/TPA induced papilloma. In the promotion and progression phase, we detected a significant enhancement in IL-10 at 8 and 16 weeks after DMBA/TPA treatment. An IL-10 autocrine or paracrine loop might play an important role in tumour cell proliferation and survival through the upregulation of antiapoptotic genes such as BCL-2 or BCL-XL[64–66]. In addition, IL-10 inhibits secretion of the proinflammatory cytokines by CD4+ T cells and impairs CD8+ T cells response, whereas tumor clearance can be enhanced in the absence of IL-10[67, 68].
In the 16th week, the cytokines IL-10, IL-17, TGF-β and TNF-α were detected at the highest overall level, creating a chronic inflammation cytokine milieu that may lead to antitumour immunity eradication and accelerated tumour progression. TGF-β enhances tumour invasion and, with TNF-α, affects stromal cells, facilitates angiogenesis, and impairs NK cells, CD8+ T cells and macrophage activity against tumours[58, 69, 70]. Additionally, TGF-β-induced inflammation in precancerous epidermal squamous lesions has been shown to require IL-17. IL-17 has also been associated with different types of cancer and may be expressed by tumour- associated macrophages and neutrophils to a lesser degree[69, 72, 73]. We found significant percentages of GR-1+ macrophages in the tumour tissue at 16 weeks (Figure4B), and this macrophage phenotype has been reported to express IL-12p40 and iNOS. However, GR1+F4/80+ cells have been reported to have negative effects on tumour protection. Neutrophils and GR-1- macrophages were the predominant cell type in lesion tissue at 4 and 8 weeks (Figure4B), and GR-1- macrophages are poor producers of NO. These data suggest that MPO and NO were primarily produced by neutrophils at the start of SCC development and establishment (Table 2). However, ELA seemed to be primarily produced by activated macrophages along with IL-10 and IL-17, correlating with lesion appearance (Table 3).
In summary, the data presented here are in according with previous studies[2–9], which show that inflammatory mediators activate the remodeling of the tumor microenvironment through recruitment of leukocytes. The data presented here expand previous observation's by demonstrate that DMBA-induced inflammatory mediators are produced in the initial phase of carcinogenesis by activated neutrophils and macrophages. These findings may have broad implications besides providing a better insight into the mechanisms involved in DMBA-induced carcinogenesis. Increase of inflammatory mediators such as NO, active MPO and ELA, which are up-regulated in response to chronic inflammation, can increase mutation rates because induce DNA damage and genomic instability, in addition to enhancing the proliferation of mutated cells[2–9]. These events are associated with tumor initiation and progression, suggesting that inflammatory mediators may play an important role in initiation and promotion phase of SCC development. These findings represent a significant step towards in carcinogenesis.
Our results suggest that activated neutrophils and macrophages are involved in inflammatory mediator production in tumour microenvironment. These cells may drive some immunity-related skin tissue damage and support cancer establishment.
This work was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo - FAPESP [grant 2011/03195-1; scholarship to R.N.R. (2006/01617-8), T.H.G. (2009/14127-7), and E.B.B. (2009/03471-9)]; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES; scholarship to C.E.O.), and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq; scholarship to J.S.S., G.P.G, and A.P.C.).
- Wherry EJ: T cell exhaustion. Nat Immunol. 2011, 12: 492-499.View ArticlePubMedGoogle Scholar
- Mika D, Guruvayoorappan C: Myeloperoxidase: the yin and yang in tumour progression. J Exp Ther Oncol. 2011, 9: 93-100.PubMedGoogle Scholar
- Sansone P, Bromberg J: Environment, inflammation, and cancer. Cur Opin Gen Develop. 2011, 21: 80-85. 10.1016/j.gde.2010.11.001.View ArticleGoogle Scholar
- Grivennikov SI, Greten FR, Karin M: Immunity, inflammation, and cancer. Cell. 2010, 140: 883-899. 10.1016/j.cell.2010.01.025.PubMed CentralView ArticlePubMedGoogle Scholar
- Nishikawa M: Reactive oxygen species in tumor metastasis. Cancer Lett. 2008, 266: 53-59. 10.1016/j.canlet.2008.02.031.View ArticlePubMedGoogle Scholar
- Wiseman H, Halliwell B: Damage to DNA by reactive oxygen and nitrogen species: role in inflammatory disease and progression to cancer. Biochem J. 1996, 313: 17-29.PubMed CentralView ArticlePubMedGoogle Scholar
- Nishikawa M, Hashida M, Takakura Y: Catalase delivery for inhibiting ROS-mediated tissue injury and tumor metastasis. Adv Drug Deliv Rev. 2009, 61: 319-326. 10.1016/j.addr.2009.01.001.View ArticlePubMedGoogle Scholar
- Lonkar P, Dedon PC: Reactive species and DNA damage in chronic inflammation: reconciling chemical mechanisms and biological fates. Int J Cancer. 2011, 128: 1999-2009. 10.1002/ijc.25815.PubMed CentralView ArticlePubMedGoogle Scholar
- Federico A, Morgillo F, Tuccillo C, Ciardiello F, Loguercio C: Chronic inflammation and oxidative stress in human carcinogenesis. Int J Cancer. 2007, 121: 2381-2386. 10.1002/ijc.23192.View ArticlePubMedGoogle Scholar
- Dale DC, Boxer L, Liles WC: The phagocytes: neutrophils and monocytes. Blood. 2008, 112: 935-945. 10.1182/blood-2007-12-077917.View ArticlePubMedGoogle Scholar
- Stiborová M, Rupertová M, Frei E: Cytochrome P450- and peroxidase-mediated oxidation of anticancer alkaloid ellipticine dictates its anti-tumor efficiency. Biochim Biophys Acta. 2011, 1814: 175-185. 10.1016/j.bbapap.2010.05.016.View ArticlePubMedGoogle Scholar
- Sun Z, Yang P: Role of imbalance between neutrophil elastase and alpha 1-antitrypsin in cancer development and progression. Lancet Oncol. 2004, 5: 182-190. 10.1016/S1470-2045(04)01414-7.View ArticlePubMedGoogle Scholar
- Sato T, Takahashi S, Mizumoto T, Harao M, Akizuki M, Takasugi M, Fukutomi T, Yamashita J: Neutrophil elastase and cancer. Surg Oncol. 2006, 15: 217-222. 10.1016/j.suronc.2007.01.003.View ArticlePubMedGoogle Scholar
- Pai SI, Westra WH: Molecular pathology of head and neck cancer: implications for diagnosis, prognosis, and treatment. Annu Rev Pathol. 2009, 4: 49-70. 10.1146/annurev.pathol.4.110807.092158.PubMed CentralView ArticlePubMedGoogle Scholar
- Parkin DM, Bray F, Ferlay J, Pisani P: Global cancer statistics, 2002. CA Cancer J Clin. 2005, 55: 74-108. 10.3322/canjclin.55.2.74.View ArticlePubMedGoogle Scholar
- Taylor CR, Sober AJ: Sun exposure and skin disease. Annu Rev Med. 1996, 47: 181-191. 10.1146/annurev.med.47.1.181.View ArticlePubMedGoogle Scholar
- Fortina AB, Piaserico S, Caforio AL, Abeni D, Alaibac M, Angelini A, Iliceto S, Peserico A: Immunosuppressive level and other risk factors for basal cell carcinoma and squamous cell carcinoma in heart transplant recipients. Arch Dermatol. 2004, 140: 1079-1085. 10.1001/archderm.140.9.1079.View ArticlePubMedGoogle Scholar
- Sluyter R, Halliday GM: Infiltration by inflammatory cells required for solar-simulated ultraviolet radiation enhancement of skin tumor growth. Cancer Immunol Immunother. 2001, 50: 151-156. 10.1007/PL00006685.View ArticlePubMedGoogle Scholar
- Lee KD, Lee HS, Jeon CH: Body fluid biomarkers for early detection of head and neck squamous cell carcinomas. Anticancer Res. 2011, 31: 1161-1167.PubMedGoogle Scholar
- Roussos ET, Condeelis JS, Patsialou A: Chemotaxis in cancer. Nat Rev Cancer. 2011, 11: 573-587. 10.1038/nrc3078.PubMed CentralView ArticlePubMedGoogle Scholar
- Pries R, Nitsch S, Wollenberg B: Role of cytokines in head and neck squamous cell carcinoma. Expert Rev Anticancer Ther. 2006, 6: 1195-1203. 10.1586/14737126.96.36.1995.View ArticlePubMedGoogle Scholar
- Reiners JJ, Pavone A, Maldve R, Fischer SM: 12-O-tetradecanoylphorbol-13-acetate-mediated systemic co-promotion in the murine skin multistage carcinogenesis protocol. Carcinogenesis. 1993, 14: 411-415. 10.1093/carcin/14.3.411.View ArticlePubMedGoogle Scholar
- Muller-Decker K, Neufang G, Berger I, Neumann M, Marks F, Furstenberger G: Transgenic cyclooxygenase-2 overexpression sensitises mouse skin for carcinogenesis. Proc Natl Acad Sci USA. 2002, 99: 12483-12488. 10.1073/pnas.192323799.PubMed CentralView ArticlePubMedGoogle Scholar
- Blumberg PM: Protein kinase C as the receptor for the phorbol ester tumor promoters: sixth Rhoads memorial award lecture. Cancer Res. 1988, 48: 1-8.PubMedGoogle Scholar
- Tauber AI: Protein kinase C and the activation of the human neutrophil NADPH-oxidase. Blood. 1987, 69: 711-720.PubMedGoogle Scholar
- De Larco JE, Wuertz BR, Furcht LT: The potential role of neutrophils in promoting the metastatic phenotype of tumors releasing interleukin-8. Clin Cancer Res. 2004, 10: 4895-4900. 10.1158/1078-0432.CCR-03-0760.View ArticlePubMedGoogle Scholar
- Waugh DJ, Wilson C: The interleukin-8 pathway in cancer. Clin Cancer Res. 2008, 14: 6735-6741. 10.1158/1078-0432.CCR-07-4843.View ArticlePubMedGoogle Scholar
- Franco M, Bustuoabad OD, di Gianni PD, Goldman A, Pasqualini CD, Ruggiero RA: A serum-mediated mechanism for concomitant resistance shared by immunogenic and non-immunogenic murine tumours. Br J Cancer. 1996, 74: 178-186. 10.1038/bjc.1996.335.PubMed CentralView ArticlePubMedGoogle Scholar
- Gasparoto TH, Sipert CR, de Oliveira CE, Porto VC, Santos CF, Campanelli AP, Lara VS: Salivary immunity in elderly individuals presented with Candida-related denture stomatitis. Gerodontology. 2012, 47: 741-748.Google Scholar
- Ziech D, Franco R, Pappa A, Panayiotidis MI: Reactive oxygen species (ROS)–induced genetic and epigenetic alterations in human carcinogenesis. Mutat Res. 2011, 711: 167-173. 10.1016/j.mrfmmm.2011.02.015.View ArticlePubMedGoogle Scholar
- Ohshima H, Tatemichi M, Sawa T: Chemical basis of inflammation-induced carcinogenesis. Arch Biochem Biophys. 2003, 417: 3-11. 10.1016/S0003-9861(03)00283-2.View ArticlePubMedGoogle Scholar
- Franco R, Schoneveld O, Georgakilas AG, Panayiotidis MI: Oxidative stress, DNA methylation and carcinogenesis. Cancer Lett. 2008, 266: 6-11. 10.1016/j.canlet.2008.02.026.View ArticlePubMedGoogle Scholar
- Ziech D, Franco R, Georgakilas AG, Georgakila S, Malamou-Mitsi V, Schoneveld O, Pappa A, Panayiotidis MI: The role of reactive oxygen species and oxidative stress in environmental carcinogenesis and biomarker development. Chem Biol Interact. 2010, 188: 334339-Google Scholar
- London SJ, Lehman TA, Taylor JA: Myeloperoxidase genetic polymorphism and lung cancer risk. Cancer Res. 1997, 57: 5001-5003.PubMedGoogle Scholar
- Cascorbi I, Henning S, Brockmöller J, Gephart J, Meisel C, Müller JM, Loddenkemper R, Roots I: Substantially reduced risk of cancer of the aerodigestive tract in subjects with variant–463A of the myeloperoxidase gene. Cancer Res. 2009, 60: 644-649.Google Scholar
- Korkmaz B, Horwitz MS, Jenne DE, Gauthier F: Neutrophil elastase, proteinase 3, and cathepsin G as therapeutic targets in human diseases. Pharmacol Rev. 2010, 62: 726-759. 10.1124/pr.110.002733.PubMed CentralView ArticlePubMedGoogle Scholar
- Schultz J, Kaminker K: Myeloperoxidase of the leukocyte of normal human blood. I. Content and localization. Arch Biochem Biophys. 1962, 96: 465-467. 10.1016/0003-9861(62)90321-1.View ArticlePubMedGoogle Scholar
- Klebanoff SJ: Myeloperoxidase: Friend and foe. J Leukoc Biol. 2005, 77: 598-625. 10.1189/jlb.1204697.View ArticlePubMedGoogle Scholar
- Ambrosone CB, Barlow WE, Reynolds W, Livingston RB, Yeh IT, Choi JY, Davis W, Rae JM, Tang L, Hutchins LR, Ravdin PM, Martino S: Myeloperoxidase genotypes and enhanced efficacy of chemotherapy for early-stage breast cancer in SWOG-8897. J Clin Oncol. 2009, 27: 4973-4979. 10.1200/JCO.2009.21.8669.PubMed CentralView ArticlePubMedGoogle Scholar
- Lanza F, Fietta A, Spisani S, Castoldi GL, Traniello S: Does a relationship exist between neutrophil myeloperoxidase deficiency and the occurrence of neoplasms?. J Clin Lab Immunol. 1987, 22: 175-180.PubMedGoogle Scholar
- Lanza F, Giuliani AL, Amelotti F, Spisani S, Traniello S, Castoldi G: Depressed neutrophil-mediated tumor cell cytotoxicity in subjects affected by hereditary myeloperoxidase deficiency and secondary neoplasia. Haematologica. 1998, 73: 355-358.Google Scholar
- Weitzman SA, Gordon LI: Inflammation and cancer: role of phagocyte-generated oxidants in carcinogenesis. Blood. 1990, 76: 655-663.PubMedGoogle Scholar
- Liotta LA, Stetler-Stevenson WG: Tumor invasion and metastasis: an imbalance of positive and negative regulation. Cancer Res. 1991, 51: 5054-5059.Google Scholar
- Nakajima M, Chop AM: Tumor invasion and extracellular matrix degradative enzymes: regulation of activity by organ factors. Semin Cancer Biol. 1991, 2: 115-127.PubMedGoogle Scholar
- Zeydel M, Nakagawa S, Biempica L, Takahashi S: Collagenase and elastase production by mouse mammary adenocarcinoma primary cultures and cloned cells. Cancer Res. 1986, 46: 6438-6445.PubMedGoogle Scholar
- Grant AJ, Lerro KA, Wu CW: Cell associated elastase activities of rat mammary tumour cells. Bioch. Int. 1990, 22: 1077-1084.Google Scholar
- Baugh RJ, Travis J: Human leukocyte granule elastase: rapid isolation and characterization. Biochemistry. 1976, 15: 836-841. 10.1021/bi00649a017.View ArticlePubMedGoogle Scholar
- Banda MJ, Werb Z: Mouse macrophage elastase. Bioc J. 1981, 193: 589-605.View ArticleGoogle Scholar
- Karin M, Greten FR: NF-kB: linking inflammation and immunity to cancer development and progression. Nat Rev Immunol. 2005, 5: 749-759. 10.1038/nri1703.View ArticlePubMedGoogle Scholar
- Karin M: Nuclear factor-kB in cancer development and progression. Nature. 2006, 441: 431-436. 10.1038/nature04870.View ArticlePubMedGoogle Scholar
- Naugler WE, Karin M: The wolf in sheep’s clothing: the role of interleukin-6 in immunity, inflammation and cancer. Trends Mol Med. 2008, 14: 109-119. 10.1016/j.molmed.2007.12.007.View ArticlePubMedGoogle Scholar
- Hong DS, Angelo LS, Kurzrock R: Interleukin-6 and its receptor in cancer: implications for translational therapeutics. Cancer. 2007, 110: 1911-1928. 10.1002/cncr.22999.View ArticlePubMedGoogle Scholar
- Tomlins C, Storey A: Cutaneous HPV5 E6 causes increased expression of Osteoprotegerin and Interleukin 6 which contribute to evasion of UV-induced apoptosis. Carcinogenesis. 2010, 31: 2155-2164. 10.1093/carcin/bgq200.View ArticlePubMedGoogle Scholar
- Jimi E, Furuta H, Matsuo K, Tominaga K, Takahashi T, Nakanishi O: The cellular and molecular mechanisms of bone invasion by oral squamous cell carcinoma. Oral Dis. 2011, 17: 462-468. 10.1111/j.1601-0825.2010.01781.x.View ArticlePubMedGoogle Scholar
- Hussain SP, Hofseth LJ, Harris CC: Radical causes of cancer. Nat Rev Cancer. 2003, 3: 276-285. 10.1038/nrc1046.View ArticlePubMedGoogle Scholar
- Huang S, Ullrich SE, Bar-Eli M: Regulation of tumor growth and metastasis by interleukin-10: the melanoma experience. J Interferon Cytokine Res. 1999, 19: 697-703. 10.1089/107999099313532.View ArticlePubMedGoogle Scholar
- Kohno T, Mizukami H, Suzuki M, Saga Y, Takei Y, Shimpo M, Matsushita T, Okada T, Hanazono Y, Kume A, Sato I, Ozawa K: Interleukin-10-mediated inhibition of angiogenesis and tumor growth in mice bearing VEGF-producing ovarian cancer. Cancer Res. 2003, 63: 5091-5094.PubMedGoogle Scholar
- Lin WW, Karin M: A cytokine-mediated link between innate immunity, inflammation, and cancer. J Clin Invest. 2007, 117: 1175-1183. 10.1172/JCI31537.PubMed CentralView ArticlePubMedGoogle Scholar
- Terabe M, Park JM, Berzofsky JA: Role of IL-13 in regulation of anti-tumor immunity and tumor growth. Cancer Immunol Immunother. 2004, 53: 79-85. 10.1007/s00262-003-0445-0.View ArticlePubMedGoogle Scholar
- Teng MW, Darcy PK, Smyth MJ: Stable IL-10: a new therapeutic that promotes tumor immunity. Cancer Cell. 2011, 20: 691-693. 10.1016/j.ccr.2011.11.020.View ArticlePubMedGoogle Scholar
- Asadullah K, Sterry W, Volk HD: Interleukin-10 therapy–review of a new approach. Pharmacol Rev. 2003, 55: 241-269. 10.1124/pr.55.2.4.View ArticlePubMedGoogle Scholar
- Cervenak L, Morbidelli L, Donati D, Donnini S, Kambayashi T, Wilson JL, Axelson H, Castaños-Velez E, Ljunggren HG, Malefyt RD, Granger HJ, Ziche M: Abolished angiogenicity and tumorigenicity of Burkitt lymphoma by interleukin-10. Blood. 2000, 96: 2568-2573.PubMedGoogle Scholar
- Mumm JB, Emmerich J, Zhang X, Chan I, Wu L, Mauze S, Blaisdell S, Basham B, Dai J, Grein J, Sheppard C, Hong K: IL-10 elicits IFNγ-dependent tumor immune surveillance. Cancer Cell. 2011, 20: 781-796. 10.1016/j.ccr.2011.11.003.View ArticlePubMedGoogle Scholar
- Alas S, Emmanouilides C, Bonavida B: Inhibition of interleukin 10 by rituximab results in down-regulation of bcl-2 and sensitization of B-cell non-Hodgkin’s lymphoma to apoptosis. Clin Cancer Res. 2001, 7: 709-723.PubMedGoogle Scholar
- Sredni B, Weil M, Khomenok G, Lebenthal I, Teitz S, Mardor Y, Ram Z, Orenstein A, Kershenovich A, Michowiz S, Cohen YI, Rappaport ZH: Ammonium trichloro(dioxoethylene-o, o’)tellurate (AS101) sensitizes tumors to chemotherapy by inhibiting the tumor interleukin 10 autocrine loop. Cancer Res. 2004, 64: 1843-1852. 10.1158/0008-5472.CAN-03-3179.View ArticlePubMedGoogle Scholar
- Alas S, Bonavida B: Rituximab inactivates signal transducer and activation of transcription 3 (STAT3) activity in B-non-Hodgkin’s lymphoma through inhibition of the interleukin 10 autocrine/paracrine loop and results in down-regulation of Bcl-2 and sensitization to cytotoxic drugs. Cancer Res. 2001, 61: 5137-5144.PubMedGoogle Scholar
- Brooks DG, Trifilo MJ, Edelmann KH, Teyton L, McGavern DB, Oldstone MB: Interleukin-10 determines viral clearance or persistence in vivo. Nat Med. 2006, 12: 1301-1309. 10.1038/nm1492.PubMed CentralView ArticlePubMedGoogle Scholar
- Vicari AP, Trinchieri G: Interleukin-10 in viral diseases and cancer: exiting the labyrinth?. Immunol Rev. 2004, 202: 223-236. 10.1111/j.0105-2896.2004.00216.x.View ArticlePubMedGoogle Scholar
- Numasaki M, Fukushi J, Ono M, Narula SK, Zavodny PJ, Kudo T, Robbins PD, Tahara H, Lotze MT: Interleukin-17 promotes angiogenesis and tumor growth. Blood. 2003, 101: 2620-2627. 10.1182/blood-2002-05-1461.View ArticlePubMedGoogle Scholar
- Tian M, Neil JR, Schiemann WP: Transforming growth factor-β and the hallmarks of cancer. Cell Signal. 2011, 23: 951-962. 10.1016/j.cellsig.2010.10.015.PubMed CentralView ArticlePubMedGoogle Scholar
- Mohammed J, Ryscavage A, Perez-Lorenzo R, Gunderson AJ, Blazanin N, Glick AB: TGFβ1-induced inflammation in precancerous epidermal squamous lesions requires IL-17. J Invest Dermatol. 2010, 130: 2295-2303. 10.1038/jid.2010.92.View ArticlePubMedGoogle Scholar
- Wilke CM, Kryczek I, Wei S, Zhao E, Wu K, Wang G, Zou W: Th17 cells in cancer: help or hindrance?. Carcinogenesis. 2011, 32: 643-649. 10.1093/carcin/bgr019.PubMed CentralView ArticlePubMedGoogle Scholar
- Vykhovanets EV, Maclennan GT, Vykhovanets OV, Gupta S: IL-17 Expression by macrophages is associated with proliferative inflammatory atrophy lesions in prostate cancer patients. Int J Clin Exp Pathol. 2011, 4: 552-565.PubMed CentralPubMedGoogle Scholar
- Mordue DG, Sibley LD: A novel population of Gr-1+-activated macrophages induced during acute toxoplasmosis. J Leukoc Biol. 2003, 74: 1015-1025. 10.1189/jlb.0403164.View ArticlePubMedGoogle Scholar
- Liu YY, Sun LC, Wei JJ, Li D, Yuan Y, Yan B, Liang ZH, Zhu HF, Xu Y, Li B, Song CW, Liao SJ: Tumor cell-released TLR4 ligands stimulate Gr-1+CD11b+F4/80+ cells to induce apoptosis of activated T cells. J Immunol. 2010, 185: 2773-2782. 10.4049/jimmunol.1000772.View ArticlePubMedGoogle Scholar
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