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Nicotinic receptor β2 determines NK cell-dependent metastasis in a murine model of metastatic lung cancer.

Hao J, Shi FD, Abdelwahab M, Shi SX, Simard A, Whiteaker P, Lukas R, Zhou Q - PLoS ONE (2013)

Bottom Line: Further, nicotinic suppression of NF-κB-induced transcriptional activity in NK cells is dependent on nAChR β2.This nAChR subtype also plays a large role in the NK cell-mediated control of melanoma lung metastasis, in a murine lung metastasis model exposed to nicotine.Our findings suggest nAChR β2 as a prominent pathway for nicotine induced impairment of NK cell functions which contributes to the occurrence of smoking-related pathologies.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Tianjin Neurological Institute, Tianjin Medical University General Hospital, Tianjin, China. jhao0216@gmail.com

ABSTRACT
Cigarette smoke exposure markedly compromises the ability of the immune system to protect against invading pathogens and tumorigenesis. Nicotine is a psychoactive component of tobacco products that acts as does the natural neurotransmitter, acetylcholine, on nicotinic receptors (nAChRs). Here we demonstrate that natural killer (NK) cells strongly express nAChR β2. Nicotine exposure impairs the ability of NK cells to kill target cells and release cytokines, a process that is largely abrogated by nAChR β2 deficiency. Further, nicotinic suppression of NF-κB-induced transcriptional activity in NK cells is dependent on nAChR β2. This nAChR subtype also plays a large role in the NK cell-mediated control of melanoma lung metastasis, in a murine lung metastasis model exposed to nicotine. Our findings suggest nAChR β2 as a prominent pathway for nicotine induced impairment of NK cell functions which contributes to the occurrence of smoking-related pathologies.

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Impairment of NK cell-dependent suppression of B16 tumor cell metastasis by nicotine is mediated by nAChR β2.Mice of different genotypes received nicotine (Nic) or PBS for 21 days and engrafted with the B16 melanoma cell line (1×106 cells/mouse). A. Seven or 14 days later, a portion of mice were euthanized and the lung dissected. Total numbers of melanoma nodules counted in these organs are shown (n = 12 mice/group). B, C. Quantification of tumor growth in these animals during the period are achieved via bioluminescence imaging (B) and high field MRI (C for T1 images; Figure S2 denotes Th2 images. N = 15–18/group. P values, ANOVA, *p<0.05. D. Survival for the remaining animals are monitored for 60 days (n = 15–18 mice/group). E. Mice were engrafted with melanoma cells lines (1×106/mouse) in the presence or absence of nicotine, and NK cells (5×105 NK cells/mouse) from wild type or nAChR β2−/− mice. Mice were then monitored for survival up to 60 days. Results are pooled from three experiments with similar results. N = 6–8 mice/group.
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pone-0057495-g005: Impairment of NK cell-dependent suppression of B16 tumor cell metastasis by nicotine is mediated by nAChR β2.Mice of different genotypes received nicotine (Nic) or PBS for 21 days and engrafted with the B16 melanoma cell line (1×106 cells/mouse). A. Seven or 14 days later, a portion of mice were euthanized and the lung dissected. Total numbers of melanoma nodules counted in these organs are shown (n = 12 mice/group). B, C. Quantification of tumor growth in these animals during the period are achieved via bioluminescence imaging (B) and high field MRI (C for T1 images; Figure S2 denotes Th2 images. N = 15–18/group. P values, ANOVA, *p<0.05. D. Survival for the remaining animals are monitored for 60 days (n = 15–18 mice/group). E. Mice were engrafted with melanoma cells lines (1×106/mouse) in the presence or absence of nicotine, and NK cells (5×105 NK cells/mouse) from wild type or nAChR β2−/− mice. Mice were then monitored for survival up to 60 days. Results are pooled from three experiments with similar results. N = 6–8 mice/group.

Mentions: Cigarette smoke has been experimentally demonstrated to increase lung metastatic tumor burden [11]. As multiple chemicals contained in cigarette smoke can have this effect, we sought to specifically address the role of nicotine exposure in this process. To this end, we adopted the murine B16 cell line derived from spontaneous murine melanoma. Because B16 tumor cells have high lung metastasis potential and such metastasis can be inhibited by NK cells, this model is ideal to address the role of nicotine and its receptors in this pathological process. For this purpose, C57BL/6 RAG2−/− mice were treated with nicotine or PBS via osmotic pump implantation for 14 days and beyond. The dosage selection is based on smokers and justified in detail in the methods section and in our previous publications [7], [8]. These mice were then challenged i.v. with 1×106 B16- melanoma cells. Based on the literature [11], [15], [16], we did preparation experiments in which tumor burden and survival rates were compared in mice receiving 1×105, 2.5×105, 5×105, 1×106 and 2.5×106 B16 cells. We found that transplantation of 1×106 provided the most efficient comparison of tumor burden, and thus this concentration was used for all subsequent experiments (Table S1). 14 days of nicotine or PBS exposure at the onset of tumor challenge lead to no significant difference in tumor burden between the two groups (data not shown). Nicotine was thus continuously released in these mice until 21 days post tumor challenge. Compared with control mice that received PBS, mice treated with nicotine had significantly greater lung tumor burden (Figure S1; Figure 5A), increased bioluminescence imaging (Figure 5B),tumor volume when assessed by high field MRI of both T1 (Figure 5C) and T2 imaging (Figure S2), as well as decreased survival rates (Figure 5D).


Nicotinic receptor β2 determines NK cell-dependent metastasis in a murine model of metastatic lung cancer.

Hao J, Shi FD, Abdelwahab M, Shi SX, Simard A, Whiteaker P, Lukas R, Zhou Q - PLoS ONE (2013)

Impairment of NK cell-dependent suppression of B16 tumor cell metastasis by nicotine is mediated by nAChR β2.Mice of different genotypes received nicotine (Nic) or PBS for 21 days and engrafted with the B16 melanoma cell line (1×106 cells/mouse). A. Seven or 14 days later, a portion of mice were euthanized and the lung dissected. Total numbers of melanoma nodules counted in these organs are shown (n = 12 mice/group). B, C. Quantification of tumor growth in these animals during the period are achieved via bioluminescence imaging (B) and high field MRI (C for T1 images; Figure S2 denotes Th2 images. N = 15–18/group. P values, ANOVA, *p<0.05. D. Survival for the remaining animals are monitored for 60 days (n = 15–18 mice/group). E. Mice were engrafted with melanoma cells lines (1×106/mouse) in the presence or absence of nicotine, and NK cells (5×105 NK cells/mouse) from wild type or nAChR β2−/− mice. Mice were then monitored for survival up to 60 days. Results are pooled from three experiments with similar results. N = 6–8 mice/group.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3585320&req=5

pone-0057495-g005: Impairment of NK cell-dependent suppression of B16 tumor cell metastasis by nicotine is mediated by nAChR β2.Mice of different genotypes received nicotine (Nic) or PBS for 21 days and engrafted with the B16 melanoma cell line (1×106 cells/mouse). A. Seven or 14 days later, a portion of mice were euthanized and the lung dissected. Total numbers of melanoma nodules counted in these organs are shown (n = 12 mice/group). B, C. Quantification of tumor growth in these animals during the period are achieved via bioluminescence imaging (B) and high field MRI (C for T1 images; Figure S2 denotes Th2 images. N = 15–18/group. P values, ANOVA, *p<0.05. D. Survival for the remaining animals are monitored for 60 days (n = 15–18 mice/group). E. Mice were engrafted with melanoma cells lines (1×106/mouse) in the presence or absence of nicotine, and NK cells (5×105 NK cells/mouse) from wild type or nAChR β2−/− mice. Mice were then monitored for survival up to 60 days. Results are pooled from three experiments with similar results. N = 6–8 mice/group.
Mentions: Cigarette smoke has been experimentally demonstrated to increase lung metastatic tumor burden [11]. As multiple chemicals contained in cigarette smoke can have this effect, we sought to specifically address the role of nicotine exposure in this process. To this end, we adopted the murine B16 cell line derived from spontaneous murine melanoma. Because B16 tumor cells have high lung metastasis potential and such metastasis can be inhibited by NK cells, this model is ideal to address the role of nicotine and its receptors in this pathological process. For this purpose, C57BL/6 RAG2−/− mice were treated with nicotine or PBS via osmotic pump implantation for 14 days and beyond. The dosage selection is based on smokers and justified in detail in the methods section and in our previous publications [7], [8]. These mice were then challenged i.v. with 1×106 B16- melanoma cells. Based on the literature [11], [15], [16], we did preparation experiments in which tumor burden and survival rates were compared in mice receiving 1×105, 2.5×105, 5×105, 1×106 and 2.5×106 B16 cells. We found that transplantation of 1×106 provided the most efficient comparison of tumor burden, and thus this concentration was used for all subsequent experiments (Table S1). 14 days of nicotine or PBS exposure at the onset of tumor challenge lead to no significant difference in tumor burden between the two groups (data not shown). Nicotine was thus continuously released in these mice until 21 days post tumor challenge. Compared with control mice that received PBS, mice treated with nicotine had significantly greater lung tumor burden (Figure S1; Figure 5A), increased bioluminescence imaging (Figure 5B),tumor volume when assessed by high field MRI of both T1 (Figure 5C) and T2 imaging (Figure S2), as well as decreased survival rates (Figure 5D).

Bottom Line: Further, nicotinic suppression of NF-κB-induced transcriptional activity in NK cells is dependent on nAChR β2.This nAChR subtype also plays a large role in the NK cell-mediated control of melanoma lung metastasis, in a murine lung metastasis model exposed to nicotine.Our findings suggest nAChR β2 as a prominent pathway for nicotine induced impairment of NK cell functions which contributes to the occurrence of smoking-related pathologies.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Tianjin Neurological Institute, Tianjin Medical University General Hospital, Tianjin, China. jhao0216@gmail.com

ABSTRACT
Cigarette smoke exposure markedly compromises the ability of the immune system to protect against invading pathogens and tumorigenesis. Nicotine is a psychoactive component of tobacco products that acts as does the natural neurotransmitter, acetylcholine, on nicotinic receptors (nAChRs). Here we demonstrate that natural killer (NK) cells strongly express nAChR β2. Nicotine exposure impairs the ability of NK cells to kill target cells and release cytokines, a process that is largely abrogated by nAChR β2 deficiency. Further, nicotinic suppression of NF-κB-induced transcriptional activity in NK cells is dependent on nAChR β2. This nAChR subtype also plays a large role in the NK cell-mediated control of melanoma lung metastasis, in a murine lung metastasis model exposed to nicotine. Our findings suggest nAChR β2 as a prominent pathway for nicotine induced impairment of NK cell functions which contributes to the occurrence of smoking-related pathologies.

Show MeSH
Related in: MedlinePlus