Effect of group III phospholipase A2 deletion in azoxymethane-induced colon carcinogenesis modeled colon
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ABSTRACT: Lipid mediators play pivotal roles in colorectal cancer and colitis, but only a limited member of the phospholipase A2 (PLA2) subtypes, which lie upstream of various lipid mediators, have been implicated in the positive or negative regulation of these diseases. Clinical and biochemical evidence suggests that secreted PLA2 group III (sPLA2-III) is associated with colorectal cancer, although its precise role remains obscure. Here we have found that sPLA2-III-null (Pla2g3-/-) mice are highly resistant to colon carcinogenesis. Furthermore, Pla2g3-/- mice are less susceptible to dextran sulfateinduced colitis, implying that the amelioration of colonic inflammation by sPLA2-III ablation may underlie the protective effect against colon cancer. Lipidomics analysis of the colon revealed significant reduction of pro-inflammatory/pro-tumorigenic lysophosholipids as well as unusual elevation of colon-protective fatty acids and their oxygenated metabolites in Pla2g3-/- mice. Overall, our results establish a role of sPLA2-III in the promotion of colorectal inflammation and cancer, expand our understanding of the divergent roles of multiple PLA2 enzymes in the gastrointestinal tract, and point to sPLA2-III as a novel druggable target for colorectal diseases.
Project description:Asthma is a chronic inflammatory disease of the airways characterized by recurrent episodes of airway obstruction, hyperresponsiveness, remodeling, and eosinophilia. Phospholipase A2s (PLA2s), which release fatty acids and lysophospholipids from membrane phospholipids, have been implicated in exacerbating asthma by generating pro-asthmatic lipid mediators, but an understanding of the association between individual PLA2 subtypes and asthma is still incomplete. Here, we show that group III secreted PLA2 (sPLA2-III) plays an ameliorating, rather than aggravating, role in asthma pathology. In both mouse and human lungs, sPLA2-III was expressed in bronchial epithelial cells and decreased during the asthmatic response. In an ovalbumin (OVA)-induced asthma model, Pla2g3-/- mice exhibited enhanced airway hyperresponsiveness, eosinophilia, OVA-specific IgE production, and type 2 cytokine expression as compared to Pla2g3+/+ mice. Lipidomics analysis showed that the pulmonary levels of several lysophospholipids, including lysophosphatidylcholine, lysophosphatidylethanolamine, and lysophosphatidic acid (LPA), were decreased in OVA-challenged Pla2g3-/- mice relative to Pla2g3+/+ mice. LPA receptor 2 agonists suppressed thymic stromal lymphopoietin expression in bronchial epithelial cells and reversed airway hyperresponsiveness and eosinophilia in Pla2g3-/- mice, suggesting that sPLA2-III negatively regulates allergen-induced asthma at least by producing LPA. Thus, the activation of the sPLA2-III-LPA pathway may be a new therapeutic target for allergic asthma. Microarray gene profiling of the OVA-challenged lung revealed that the genes related to cytokines and inflammatory response were highly changed in Pla2g3-/- mice relative to Pla2g3+/+ mice
Project description:Asthma is a chronic inflammatory disease of the airways characterized by recurrent episodes of airway obstruction, hyperresponsiveness, remodeling, and eosinophilia. Phospholipase A2s (PLA2s), which release fatty acids and lysophospholipids from membrane phospholipids, have been implicated in exacerbating asthma by generating pro-asthmatic lipid mediators, but an understanding of the association between individual PLA2 subtypes and asthma is still incomplete. Here, we show that group III secreted PLA2 (sPLA2-III) plays an ameliorating, rather than aggravating, role in asthma pathology. In both mouse and human lungs, sPLA2-III was expressed in bronchial epithelial cells and decreased during the asthmatic response. In an ovalbumin (OVA)-induced asthma model, Pla2g3 knockout (-/-) mice exhibited enhanced airway hyperresponsiveness, eosinophilia, OVA-specific IgE production, and type 2 cytokine expression as compared to Pla2g3 wild-type (+/+) mice. Lipidomics analysis showed that the pulmonary levels of several lysophospholipids, including lysophosphatidylcholine, lysophosphatidylethanolamine, and lysophosphatidic acid (LPA), were decreased in OVA-challenged Pla2g3-/- mice relative to Pla2g3+/+ mice. LPA receptor 2 agonists suppressed thymic stromal lymphopoietin expression in bronchial epithelial cells and reversed airway hyperresponsiveness and eosinophilia in Pla2g3-/- mice, suggesting that sPLA2-III negatively regulates allergen-induced asthma at least by producing LPA. Thus, the activation of the sPLA2-III-LPA pathway may be a new therapeutic target for allergic asthma. Microarray gene profiling of the bronchial epithelial cells isolated from OVA-challenged lung revealed the increased expression of various chemokines and type 2 epithelial cytokines in bronchial epithelial cells from Pla2g3-/- mice as compared to those from Pla2g3+/+ mice following OVA challenge.
Project description:Within the secreted phospholipase A2 (sPLA2) family, group X sPLA2 (sPLA2-X) has the highest capacity to hydrolyze cellular membranes and has long been thought to promote inflammation by releasing arachidonic acid (AA), a precursor of pro-inflammatory eicosanoids. Unexpectedly, we found that transgenic mice globally overexpressing human sPLA2-X (PLA2G10-Tg) displayed striking immunosuppressive and lean phenotypes with lymphopenia and increased M2-like macrophages, accompanied by marked elevation of free omega-3 polyunsaturated fatty acids (PUFAs) and their metabolites. Studies using Pla2g10-deficient mice revealed that endogenous sPLA2-X, which is highly expressed in the colon epithelium and spermatozoa, mobilized omega-3 PUFAs or their metabolites to protect against dextran sulfate sodium (DSS)-induced colitis and to promote fertilization, respectively. In colitis, sPLA2-X deficiency increased colorectal expression of Th17 cytokines, and omega-3 PUFAs attenuated their production by lamina propria cells partly through the fatty acid receptor GPR120. In comparison, cytosolic phospholipase A2 (cPLA2alpha) protects from colitis by mobilizing omega-6 AA metabolites including prostaglandin E2. Thus, our results underscore a previously unrecognized role of sPLA2-X as an omega-3 PUFA mobilizer in vivo, segregated mobilization of omega-3 and omega-6 PUFA metabolites by sPLA2-X and cPLA2alpha, respectively, in protection against colitis, and the novel role of a particular sPLA2-X-driven PUFA in fertilization.
Project description:We obtained snap-frozen tissue samples from 20 colorectal cancer (CRC) patients with stage III disease who had undergone curative resection. The expression profiles were determined using Affymetrix Human Genome U133Plus 2.0 arrays. We used microarrays to identify potential gene deregulation correlated with the outcomes of colon cancer patients.
Project description:Purpose: A 128-gene signature has been proposed to predict poor outcomes in patients with stage II and III colorectal cancer. In the present study we aimed to validate this previously published 128-gene signature on external and independent data from patients with stage II and III colon cancer.
Project description:Background and Aims: Staging inadequately predicts metastatic risk in colon cancer patients. We used a gene expression profile derived from invasive murine colon cancer cells that were highly metastatic in an immunocompetent mouse model to identify colon cancer patients at risk for recurrence in a phase I, exploratory biomarker study. Methods: 55 colorectal cancer patients from Vanderbilt Medical Center (VMC) were used as the training dataset and 177 patients from the Moffitt Cancer Center were used as the independent dataset. The metastasis-associated gene expression profile developed from the mouse model was refined using comparative functional genomics in the VMC gene expression profiles to identify a 34-gene classifier associated with high risk of metastasis and death from colon cancer. A recurrence score derived from the biologically based classifier was tested in the Moffitt dataset. Results: A high score was significantly associated with increased risk of metastasis and death from colon cancer across all pathological stages and specifically in stage II and stage III patients. The recurrence score was shown to independently predict risk of cancer recurrence and death in both univariate and multivariate models. For example, among stage III patients, a high score translated to increased relative risk for cancer recurrence (hazard ratio = 4.7 (95% CI=1.566-14.05)). Furthermore, the recurrence score identified stage III patients whose five-year recurrence-free survival was >88% and for whom adjuvant chemotherapy did not provide improved survival. Conclusion: Our biologically based gene expression profile yielded a potentially useful classifier to predict cancer recurrence and death independently of conventional measures in colon cancer patients. Experiment Overall Design: Gene expression array differences between highly invasive mouse colon cancer cells and non-invasive colon cancer cells were used to develop a metastasis gene expression profile. It was refined using gene expression data from 55 patient (VMC) samples and trained using 177 patient (Moffitt) samples.
Project description:We obtained snap-frozen tissue samples from 20 colorectal cancer (CRC) patients with stage III disease who had undergone curative resection. The expression profiles were determined using Affymetrix Human Genome U133Plus 2.0 arrays. We used microarrays to identify potential gene deregulation correlated with the outcomes of colon cancer patients. mRNA from 20 primary colorectal tumour samples were extracted and hybridized to HG-U133Plus 2.0 expression arrays. The NexusExp3 procedure was used to make calls of expression. Of the 20 patients, 7 had disease relapse within 3 years after surgery.
Project description:Background and Aims: Staging inadequately predicts metastatic risk in colon cancer patients. We used a gene expression profile derived from invasive murine colon cancer cells that were highly metastatic in an immunocompetent mouse model to identify colon cancer patients at risk for recurrence in a phase I, exploratory biomarker study. Methods: 55 colorectal cancer patients from Vanderbilt Medical Center (VMC) were used as the training dataset and 177 patients from the Moffitt Cancer Center were used as the independent dataset. The metastasis-associated gene expression profile developed from the mouse model was refined using comparative functional genomics in the VMC gene expression profiles to identify a 34-gene classifier associated with high risk of metastasis and death from colon cancer. A recurrence score derived from the biologically based classifier was tested in the Moffitt dataset. Results: A high score was significantly associated with increased risk of metastasis and death from colon cancer across all pathological stages and specifically in stage II and stage III patients. The recurrence score was shown to independently predict risk of cancer recurrence and death in both univariate and multivariate models. For example, among stage III patients, a high score translated to increased relative risk for cancer recurrence (hazard ratio = 4.7 (95% CI=1.566-14.05)). Furthermore, the recurrence score identified stage III patients whose five-year recurrence-free survival was >88% and for whom adjuvant chemotherapy did not provide improved survival. Conclusion: Our biologically based gene expression profile yielded a potentially useful classifier to predict cancer recurrence and death independently of conventional measures in colon cancer patients. Experiment Overall Design: Gene expression array differences between highly invasive mouse colon cancer cells and non-invasive colon cancer cells were used to develop a metastasis gene expression profile. It was refined using gene expression data from 55 patient (VMC) samples and trained using 177 patient (Moffitt) samples.
Project description:Chronic inflammation of the intestine has been associated with an elevated risk of developing colorectal cancer. Recent association studies have highlighted the role of genetic predisposition in the etiology of colitis and started to unravel its complexity. However, the genetic factors influencing the progression from colon inflammation to tumorigenesis are not known. We used Helicobacter hepaticus-induced colitis in a 129.RAG(-/-) mouse model to explore early onset of the disease. Experiments purpose and justifications: to elucidate early genes and pathways changed in the mouse strain susceptible to innate colitis triggered by Hh infection. Experimental factors: steady state, and days 2 and 4 of infection (n=4 mice per condition). The time course is validated on the same samples using qPCR for inflammatory genes. Samples: RNA from proximal mouse colon. Two mouse genetic strains are compared 129Rag-/- (susceptible) and 129.R17Rag-/- (protected from colitis).
Project description:Chronic inflammation underlies tumor initiation, progression, invasion, and metastasis. In the colon, long-term exposure to chronic inflammation drives colitis associated colon cancer (CAC) in patients with inflammatory bowel disease (IBD). While the causal and clinical links between chronic inflammation and CAC are well established, our molecular understanding of how chronic inflammation leads to the development of colon cancer is still lacking. Here we deconstruct the evolving microenvironment of CAC, by measuring proteomic changes and extracellular matrix (ECM) organization over time in a genetically modified mouse model of CAC. We detect early changes in ECM structure and composition, and report that the transcriptional regulator heat shock factor 1 (HSF1) plays a crucial role in orchestrating these events. Activated in stromal fibroblasts of the gut, HSF1 promotes ECM remodeling and inflammatory programs which lead to the development of CAC. Loss of HSF1 abrogates ECM assembly by colon fibroblasts in cell culture, prevents inflammation-induced ECM remodeling in mice and significantly inhibits progression to CAC. Establishing the relevance of our experimental findings to human disease, we find high activation of stromal HSF1 in CAC patients, and detect the HSF1-dependent proteomic ECM signature in human colorectal cancer. Thus, HSF1-dependent ECM remodeling plays a crucial role in mediating inflammation-driven colon cancer.