Here we show that macrophage-derived factors, in addition to supporting the growth of tumor cells, also promote their survival upon treatment with TNF-related apoptosis inducing ligand (TRAIL), a potent initiator of the extrinsic pathway of apoptosis

Here we show that macrophage-derived factors, in addition to supporting the growth of tumor cells, also promote their survival upon treatment with TNF-related apoptosis inducing ligand (TRAIL), a potent initiator of the extrinsic pathway of apoptosis. TRAIL initiates apoptosis by binding to two death receptors, DR4 and DR5, while binding to the decoy receptors which lack the death website, such as DCR1, DCR2 and osteoprotegerin, inhibits its pro-apoptotic activity [9]. catenin were determined by immunoblotting (right panel).(0.12 MB TIF) pone.0011700.s002.tif (114K) GUID:?078FC7B6-2A90-4CAE-946F-9A678A6B8704 Number S3: TRAIL inhibits beta-catenin/TCF4 transcriptional activity. A: HCT116 and Hke-3 cells were treated with TRAIL in the presence of pan-caspase inhibitor, ZVAD, and the cleavage of PARP and beta-catenin was determined by immunoblotting. B: HCT116 and Hke-3 cells were transfected with the TOP-FLASH reporter gene and were treated with TRAIL (10 ng/ml) in the presence of macrophages or IL1 as indicated for 24 hours.(0.16 MB TIF) pone.0011700.s003.tif (160K) GUID:?9A973607-B798-40ED-B665-9114D8C2AEA8 Figure S4: Inhibition of GSK3beta stabilizes Snail in tumor cells. HCT116 cells were treated with LiCl (10 mM) or with AR-A014418 (AR, 50 mM) for 24 hours and the levels of Snail and beta actin were determined by immunoblotting.(2.24 MB TIF) pone.0011700.s004.tif (2.1M) GUID:?3A13923A-5D61-4410-8501-399BA380A9A5 Abstract Background We recently reported that colon tumor cells stimulate macrophages to release IL-1, which in turn inactivates GSK3 and enhances Wnt signaling in colon cancer cells, generating a self-amplifying loop that promotes the growth of tumor cells. Principal Findings Here we describe that macrophages protect HCT116 and Hke-3 colon cancer cells from TRAIL-induced apoptosis. Inactivation of IL-1 by neutralizing IL-1 antibody, or silencing of IL-1 in macrophages inhibited their ability to counter TRAIL-induced apoptosis. Accordingly, IL-1 was adequate to inhibit TRAIL-induced apoptosis. TRAIL-induced CDCA8 collapse of the mitochondrial membrane potential () and activation of caspases were TMB-PS prevented by macrophages or by recombinant IL-1. Pharmacological inhibition of IL-1 launch from macrophages by vitamin D3, a potent chemopreventive agent for colorectal malignancy, restored the ability of TRAIL to induce apoptosis of tumor cells cultured with macrophages. Macrophages and IL-1 failed to inhibit TRAIL-induced apoptosis in HCT116 cells expressing dnIB, dnAKT or dnTCF4, confirming that they oppose TRAIL-induced cell death through induction of Wnt signaling in tumor cells. We showed that macrophages and TMB-PS IL-1 stabilized Snail in tumor cells in an NF-B/Wnt dependent manner and that Snail deficient tumor cells were not safeguarded from TRAIL-induced apoptosis by macrophages or by IL-1, demonstrating a crucial part of Snail in the resistance of tumor cells to TRAIL. Significance We have identified a positive opinions loop between tumor cells and macrophages that propagates the growth TMB-PS and promotes the survival of colon cancer cells: tumor cells stimulate macrophages to secrete IL-1, which in turn, promotes Wnt signaling and stabilizes Snail in tumor cells, conferring resistance to TRAIL. Vitamin D3 halts this amplifying loop by interfering with the launch of IL-1 from macrophages. Accordingly, vitamin D3 sensitizes tumor cells to TRAIL-induced apoptosis, suggesting that the restorative efficacy of TRAIL could be augmented by this readily available chemopreventive agent. Intro Inflammation contributes to tumor progression by establishing conditions that support tumor cell growth and survival and increase their metastatic potential. Indeed, chronic inflammation offers been shown to predispose to development of a variety of tumors, a impressive example becoming inflammatory TMB-PS bowel disease, which is definitely associated with elevated risk of colon cancer [1]. Moreover, it appears that colon cancers that do not develop like a complication of inflammatory bowel disease will also be driven by swelling, because it offers been shown that regular use of NSAIDs lowers the mortality from sporadic colon cancer and results in regression of adenomas in FAP individuals, who inherit a mutation in the Apc gene [2]. Soluble factors which propagate swelling can be produced by tumor cells themselves or, more often, by cells recruited to the tumor microenvironment, such as tumor connected macrophages (TAMs). Coordinated signaling between tumor cells and nonmalignant cells in the tumor microenvironment is required for the progression of tumors, and signaling pathways that regulate the crosstalk between colon tumor cells and stroma, such as NF-B and STAT3, possess emerged as important focuses on for chemopreventive and chemotherapeutic providers [3], [4]. Similarly, TNF antagonists are in phase I/II clinical.In addition, tumors can attain resistance through a pathway that is not intrinsic to tumor cells, but originates in the tumor microenvironment, also called the tumor microenvironment mediated drug resistance (TMMDR). pone.0011700.s003.tif (160K) GUID:?9A973607-B798-40ED-B665-9114D8C2AEA8 Figure S4: Inhibition of GSK3beta stabilizes Snail in tumor cells. HCT116 cells were treated with LiCl (10 mM) or with AR-A014418 (AR, 50 mM) for 24 hours and the levels of Snail and beta actin were determined by immunoblotting.(2.24 MB TIF) pone.0011700.s004.tif (2.1M) GUID:?3A13923A-5D61-4410-8501-399BA380A9A5 Abstract Background We recently reported that colon tumor cells stimulate macrophages to release IL-1, which in turn inactivates GSK3 and enhances Wnt signaling in colon cancer cells, generating a self-amplifying loop that promotes the growth of tumor cells. Principal Findings Here we describe that macrophages protect HCT116 and Hke-3 colon cancer cells from TRAIL-induced apoptosis. Inactivation of IL-1 by neutralizing IL-1 antibody, or silencing of IL-1 in macrophages inhibited their ability to counter TRAIL-induced apoptosis. Accordingly, IL-1 was adequate to inhibit TRAIL-induced apoptosis. TRAIL-induced collapse of the mitochondrial membrane potential () and activation of caspases were prevented by macrophages or by recombinant IL-1. Pharmacological inhibition of IL-1 launch from macrophages by vitamin D3, a potent chemopreventive agent for colorectal malignancy, restored the ability of TRAIL to induce apoptosis of tumor cells cultured with macrophages. Macrophages and IL-1 failed to inhibit TRAIL-induced apoptosis in HCT116 cells expressing dnIB, dnAKT or dnTCF4, confirming that they oppose TRAIL-induced cell death through induction of Wnt signaling in tumor cells. We showed that macrophages and IL-1 stabilized Snail in tumor cells in an NF-B/Wnt dependent manner and that Snail deficient tumor cells were not safeguarded from TRAIL-induced apoptosis by macrophages or by IL-1, demonstrating a crucial part of Snail in the resistance of tumor cells to TRAIL. Significance We have identified a positive opinions loop between tumor cells and macrophages that propagates the growth and promotes the survival of colon cancer cells: tumor cells stimulate macrophages to secrete IL-1, which in turn, promotes Wnt signaling and stabilizes Snail in tumor cells, conferring resistance to TRAIL. Vitamin D3 halts this amplifying loop by interfering with the launch of IL-1 from macrophages. Accordingly, vitamin D3 sensitizes tumor cells to TRAIL-induced apoptosis, suggesting that the restorative efficacy of TRAIL could be augmented by this readily available chemopreventive agent. Intro Inflammation contributes to tumor progression by establishing conditions that support tumor cell growth and survival and increase their metastatic potential. Indeed, chronic inflammation offers been shown to predispose to development of a variety of tumors, a impressive example becoming inflammatory bowel disease, which is definitely associated with elevated risk of colon cancer [1]. Moreover, it appears that colon cancers that do not develop like a complication of inflammatory bowel disease will also be driven by swelling, because it offers been shown that regular use of NSAIDs lowers the mortality from sporadic colon cancer and results in regression of adenomas in FAP individuals, who inherit a mutation in the Apc gene [2]. Soluble factors which propagate swelling can be produced by tumor cells themselves or, more often, by cells recruited to the tumor microenvironment, such as tumor connected macrophages (TAMs). Coordinated signaling between tumor cells and nonmalignant cells in the tumor microenvironment is required for the progression of tumors, and signaling pathways that regulate the crosstalk between colon tumor cells and stroma, such as NF-B and STAT3, have emerged as important focuses on for chemopreventive and chemotherapeutic providers [3], [4]. Similarly, TNF antagonists are in phase I/II clinical tests and have been shown to be well tolerated in individuals with solid tumors [5], [6]. We recently founded that macrophages promote Wnt signaling in colon cancer cells and thus enhance their proliferation, and shown that macrophages exert their protumorigenic activity primarily through the release of IL-1 [7], [8]. Here we display that macrophage-derived factors, in addition to assisting the growth of tumor cells, also promote their survival upon treatment with TNF-related apoptosis inducing ligand (TRAIL), a potent initiator of the extrinsic pathway of apoptosis. TRAIL initiates apoptosis by binding to two death receptors, DR4 and DR5, while binding to the decoy receptors which lack the death website, such as DCR1, DCR2.