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Tumor associated macrophages protect colon cancer cells from TRAIL-induced apoptosis through IL-1beta-dependent stabilization of Snail in tumor cells.

Kaler P, Galea V, Augenlicht L, Klampfer L - PLoS ONE (2010)

Bottom Line: Macrophages and IL-1beta failed to inhibit TRAIL-induced apoptosis in HCT116 cells expressing dnIkappaB, dnAKT or dnTCF4, confirming that they oppose TRAIL-induced cell death through induction of Wnt signaling in tumor cells.Vitamin D(3) halts this amplifying loop by interfering with the release of IL-1beta from macrophages.Accordingly, vitamin D(3) sensitizes tumor cells to TRAIL-induced apoptosis, suggesting that the therapeutic efficacy of TRAIL could be augmented by this readily available chemopreventive agent.

View Article: PubMed Central - PubMed

Affiliation: Department of Oncology, Albert Einstein Cancer Center, Montefiore Medical Center, New York, New York, United States of America.

ABSTRACT

Background: We recently reported that colon tumor cells stimulate macrophages to release IL-1beta, which in turn inactivates GSK3beta 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-1beta by neutralizing IL-1beta antibody, or silencing of IL-1beta in macrophages inhibited their ability to counter TRAIL-induced apoptosis. Accordingly, IL-1beta was sufficient to inhibit TRAIL-induced apoptosis. TRAIL-induced collapse of the mitochondrial membrane potential (Delta psi) and activation of caspases were prevented by macrophages or by recombinant IL-1beta. Pharmacological inhibition of IL-1beta release from macrophages by vitamin D(3), a potent chemopreventive agent for colorectal cancer, restored the ability of TRAIL to induce apoptosis of tumor cells cultured with macrophages. Macrophages and IL-1beta failed to inhibit TRAIL-induced apoptosis in HCT116 cells expressing dnIkappaB, 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-1beta stabilized Snail in tumor cells in an NF-kappaB/Wnt dependent manner and that Snail deficient tumor cells were not protected from TRAIL-induced apoptosis by macrophages or by IL-1beta, demonstrating a crucial role of Snail in the resistance of tumor cells to TRAIL.

Significance: We have identified a positive feedback 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-1beta, which in turn, promotes Wnt signaling and stabilizes Snail in tumor cells, conferring resistance to TRAIL. Vitamin D(3) halts this amplifying loop by interfering with the release of IL-1beta from macrophages. Accordingly, vitamin D(3) sensitizes tumor cells to TRAIL-induced apoptosis, suggesting that the therapeutic efficacy of TRAIL could be augmented by this readily available chemopreventive agent.

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Macrophages and macrophage-derived factors protect colon cancer cells from TRAIL-induced apoptosis.A: HCT116 (average of 5 independent experiments) and Hke-3 cells (average of 4 independent experiments) were treated with TRAIL in the absence or the presence of macrophages or IL-1β (5 ng/ml) as indicated and the extent of apoptosis was determined after 7 hours. B: The mitochondrial membrane potential (MMP) was determined by JC1 staining 5 hours after treatment. C: Activation of caspase 8 and caspase-9 was determined in colon cancer cells treated with TRAIL (50 ng/ml) under conditions indicated. D: TRAIL- sensitive cancer cell lines were treated with TRAIL in the absence or the presence of human peripheral blood monocytes (Mo) and the extent of apoptosis was determined 7 hours after treatment. Data shown represent the average of 2 or 3 independent experiments.
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pone-0011700-g002: Macrophages and macrophage-derived factors protect colon cancer cells from TRAIL-induced apoptosis.A: HCT116 (average of 5 independent experiments) and Hke-3 cells (average of 4 independent experiments) were treated with TRAIL in the absence or the presence of macrophages or IL-1β (5 ng/ml) as indicated and the extent of apoptosis was determined after 7 hours. B: The mitochondrial membrane potential (MMP) was determined by JC1 staining 5 hours after treatment. C: Activation of caspase 8 and caspase-9 was determined in colon cancer cells treated with TRAIL (50 ng/ml) under conditions indicated. D: TRAIL- sensitive cancer cell lines were treated with TRAIL in the absence or the presence of human peripheral blood monocytes (Mo) and the extent of apoptosis was determined 7 hours after treatment. Data shown represent the average of 2 or 3 independent experiments.

Mentions: We demonstrated that macrophages induce several prosurvival signaling pathways in colon cancer cells, including NF-κB, AKT and Wnt signaling [7], [8], suggesting that the presence of macrophages could affect the response of tumor cells to therapeutic agents. HCT116 colon cancer cells are highly susceptible to TRAIL-induced apoptosis [16]. Accordingly, TRAIL significantly inhibited the clonogenic growth of HCT116 and HKe-3 cells (Fig. 1A and B), cell lines that differ only by the presence of the mutant kRas [21]. There was no reproducible difference between the responsiveness of HCT116 and Hke-3 cells to TRAIL (Fig. 1 and 2), demonstrating that the presence of mutant kRas does not regulate the responsiveness of cells to TRAIL. To determine whether macrophages alter the sensitivity of tumor cells to TRAIL, we treated HCT116 and Hke-3 cells with TRAIL in the absence or in the presence of THP1 macrophages. Remarkably, the presence of THP1 macrophages or treatment with IL-1β, a cytokine produced in cocultures of tumor cells and macrophages [7], restored the clonogenic growth of TRAIL-treated colon cancer cells (Fig. 1).


Tumor associated macrophages protect colon cancer cells from TRAIL-induced apoptosis through IL-1beta-dependent stabilization of Snail in tumor cells.

Kaler P, Galea V, Augenlicht L, Klampfer L - PLoS ONE (2010)

Macrophages and macrophage-derived factors protect colon cancer cells from TRAIL-induced apoptosis.A: HCT116 (average of 5 independent experiments) and Hke-3 cells (average of 4 independent experiments) were treated with TRAIL in the absence or the presence of macrophages or IL-1β (5 ng/ml) as indicated and the extent of apoptosis was determined after 7 hours. B: The mitochondrial membrane potential (MMP) was determined by JC1 staining 5 hours after treatment. C: Activation of caspase 8 and caspase-9 was determined in colon cancer cells treated with TRAIL (50 ng/ml) under conditions indicated. D: TRAIL- sensitive cancer cell lines were treated with TRAIL in the absence or the presence of human peripheral blood monocytes (Mo) and the extent of apoptosis was determined 7 hours after treatment. Data shown represent the average of 2 or 3 independent experiments.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2908545&req=5

pone-0011700-g002: Macrophages and macrophage-derived factors protect colon cancer cells from TRAIL-induced apoptosis.A: HCT116 (average of 5 independent experiments) and Hke-3 cells (average of 4 independent experiments) were treated with TRAIL in the absence or the presence of macrophages or IL-1β (5 ng/ml) as indicated and the extent of apoptosis was determined after 7 hours. B: The mitochondrial membrane potential (MMP) was determined by JC1 staining 5 hours after treatment. C: Activation of caspase 8 and caspase-9 was determined in colon cancer cells treated with TRAIL (50 ng/ml) under conditions indicated. D: TRAIL- sensitive cancer cell lines were treated with TRAIL in the absence or the presence of human peripheral blood monocytes (Mo) and the extent of apoptosis was determined 7 hours after treatment. Data shown represent the average of 2 or 3 independent experiments.
Mentions: We demonstrated that macrophages induce several prosurvival signaling pathways in colon cancer cells, including NF-κB, AKT and Wnt signaling [7], [8], suggesting that the presence of macrophages could affect the response of tumor cells to therapeutic agents. HCT116 colon cancer cells are highly susceptible to TRAIL-induced apoptosis [16]. Accordingly, TRAIL significantly inhibited the clonogenic growth of HCT116 and HKe-3 cells (Fig. 1A and B), cell lines that differ only by the presence of the mutant kRas [21]. There was no reproducible difference between the responsiveness of HCT116 and Hke-3 cells to TRAIL (Fig. 1 and 2), demonstrating that the presence of mutant kRas does not regulate the responsiveness of cells to TRAIL. To determine whether macrophages alter the sensitivity of tumor cells to TRAIL, we treated HCT116 and Hke-3 cells with TRAIL in the absence or in the presence of THP1 macrophages. Remarkably, the presence of THP1 macrophages or treatment with IL-1β, a cytokine produced in cocultures of tumor cells and macrophages [7], restored the clonogenic growth of TRAIL-treated colon cancer cells (Fig. 1).

Bottom Line: Macrophages and IL-1beta failed to inhibit TRAIL-induced apoptosis in HCT116 cells expressing dnIkappaB, dnAKT or dnTCF4, confirming that they oppose TRAIL-induced cell death through induction of Wnt signaling in tumor cells.Vitamin D(3) halts this amplifying loop by interfering with the release of IL-1beta from macrophages.Accordingly, vitamin D(3) sensitizes tumor cells to TRAIL-induced apoptosis, suggesting that the therapeutic efficacy of TRAIL could be augmented by this readily available chemopreventive agent.

View Article: PubMed Central - PubMed

Affiliation: Department of Oncology, Albert Einstein Cancer Center, Montefiore Medical Center, New York, New York, United States of America.

ABSTRACT

Background: We recently reported that colon tumor cells stimulate macrophages to release IL-1beta, which in turn inactivates GSK3beta 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-1beta by neutralizing IL-1beta antibody, or silencing of IL-1beta in macrophages inhibited their ability to counter TRAIL-induced apoptosis. Accordingly, IL-1beta was sufficient to inhibit TRAIL-induced apoptosis. TRAIL-induced collapse of the mitochondrial membrane potential (Delta psi) and activation of caspases were prevented by macrophages or by recombinant IL-1beta. Pharmacological inhibition of IL-1beta release from macrophages by vitamin D(3), a potent chemopreventive agent for colorectal cancer, restored the ability of TRAIL to induce apoptosis of tumor cells cultured with macrophages. Macrophages and IL-1beta failed to inhibit TRAIL-induced apoptosis in HCT116 cells expressing dnIkappaB, 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-1beta stabilized Snail in tumor cells in an NF-kappaB/Wnt dependent manner and that Snail deficient tumor cells were not protected from TRAIL-induced apoptosis by macrophages or by IL-1beta, demonstrating a crucial role of Snail in the resistance of tumor cells to TRAIL.

Significance: We have identified a positive feedback 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-1beta, which in turn, promotes Wnt signaling and stabilizes Snail in tumor cells, conferring resistance to TRAIL. Vitamin D(3) halts this amplifying loop by interfering with the release of IL-1beta from macrophages. Accordingly, vitamin D(3) sensitizes tumor cells to TRAIL-induced apoptosis, suggesting that the therapeutic efficacy of TRAIL could be augmented by this readily available chemopreventive agent.

Show MeSH
Related in: MedlinePlus