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Aflatoxin G1

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Xianghong Zhang – One of the best experts on this subject based on the ideXlab platform.

  • High mobility group box-1 protects against Aflatoxin G1-induced pulmonary epithelial cell damage in the lung inflammatory environment.
    Toxicology letters, 2020
    Co-Authors: Lifei Kang, Ling-xiao Xing, Chunping Liu, Ningfei Guo, Xiaoyi Liu, Xiuqing Wang, Wenli Guo, Shelly M. Xie, Xianghong Zhang

    Abstract:

    Abstract Aflatoxin G1 (AFG1) is a member of the carcinogenic Aflatoxin family. Our previous studies indicated that oral administration of AFG1 caused tumor necrosis factor (TNF)-α-dependent inflammation that enhanced oxidative DNA damage in alveolar epithelial cells, which may be related to AFG1-induced lung carcinogenesis. High mobility group box-1 (HMGB1) is a nuclear DNA-binding protein; the intracellular and extracellular roles of HMGB1 have been shown to contribute to DNA repair and sterile inflammation. The role of HMGB1 in DNA damage in an Aflatoxin-induced lung inflammatory environment was investigated in this study. Upregulation of HMGB1, TLR2, and RAGE was observed in AFG1-induced lung inflamed tissues and adenocarcinoma. Blocking AFG1-induced inflammation by neutralization of TNF-α inhibited the upregulation of HMGB1 in mouse lung tissues, suggesting that AFG1-induced TNF-α-dependent inflammation regulated HMGB1 expression. In the in vitro human pulmonary epithelial cell line model, Beas-2b, AFG1 directly enhanced the cytosolic translocation of HMGB1 and its extracellular secretion. The addition of extracellular soluble HMGB1 protected AFG1-induced DNA damage through the TLR2/NF-κB pathway in Beas-2b cells. In addition, blockade of endogenous HMGB1 by siRNA significantly enhanced AFG1-induced damage. Thus, our findings showed that both extracellularly-released and nuclear and cytosolic HMGB1 could protect the cell from AFG1-induced cell damage in a TNF-α-dependent lung inflammatory environment.

  • Oral administration of Aflatoxin G1 induces chronic alveolar inflammation associated with lung tumorigenesis
    Toxicology letters, 2014
    Co-Authors: Chunping Liu, Xia Yan, Ling-xiao Xing, Haitao Shen, Peilu Shao, Athena M. Soulika, Xinxing Meng, Xianghong Zhang

    Abstract:

    Abstract Our previous studies showed oral gavage of Aflatoxin G1 (AFG1) induced lung adenocarcinoma in NIH mice. We recently found that a single intratracheal administration of AFG1 caused chronic inflammatory changes in rat alveolar septum. Here, we examine whether oral gavage of AFG1 induces chronic lung inflammation and how it contributes to carcinogenesis. We evaluated chronic lung inflammatory responses in Balb/c mice after oral gavage of AFG1 for 1, 3 and 6 months. Inflammatory responses were heightened in the lung alveolar septum, 3 and 6 months after AFG1 treatment, evidenced by increased macrophages and lymphocytes infiltration, up-regulation of NF-κB and p-STAT3, and cytokines production. High expression levels of superoxide dismutase (SOD-2) and hemoxygenase-1 (HO-1), two established markers of oxidative stress, were detected in alveolar epithelium of AFG1-treated mice. Promoted alveolar type II cell (AT-II) proliferation in alveolar epithelium and angiogenesis, as well as increased COX-2 expression were also observed in lung tissues of AFG1-treated mice. Furthermore, we prolonged survival of the mice in the above model for another 6 months to examine the contribution of AFG1-induced chronic inflammation to lung tumorigenesis. Twelve months later, we observed that AFG1 induced alveolar epithelial hyperplasia and adenocarcinoma in Balb/c mice. Up-regulation of NF-κB, p-STAT3, and COX-2 was also induced in lung adenocarcinoma, thus establishing a link between AFG1-induced chronic inflammation and lung tumorigenesis. This is the first study to show that oral administration of AFG1 could induce chronic lung inflammation, which may provide a pro-tumor microenvironment to contribute to lung tumorigenesis.

  • Aflatoxin G1-induced oxidative stress causes DNA damage and triggers apoptosis through MAPK signaling pathway in A549 cells.
    Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 2013
    Co-Authors: Haitao Shen, Jun-ling Wang, Xia Yan, Ling-xiao Xing, Jing Liu, Yuan Wang, Hongguang Lian, Juan Wang, Xianghong Zhang

    Abstract:

    Our previous studies showed that Aflatoxin G1 (AFG1) could induce lung adenocarcinoma, and that the cancer cells originated from alveolar type II cells (AT-II cells). Recently, we found AFG1 induced structural impairment in rat AT-II cells, which may account for an early event in lung tumorigenesis. However, the mechanism of AFG1-induced AT-II cell damage remains unclear. DNA damage and apoptosis induced by oxidative stress are well accepted causes of cell damage. Thus, we explore whether AFG1 activates the reactive oxygen species (ROS)/MAPK/apoptosis pathway to cause cell damage in human AT-II cells like the cell line (A549). We found AFG1 induced oxidative stress by increasing ROS generation and caused DNA double-strand breaks (DSBs) by up-regulating γH2AX expression. AFG1 also triggered apoptosis in A549 cells by regulating Fas/FasL, caspase-8, Bax, Bcl-2, and activating caspase-3. Pre-treatment with antioxidant n-acetyl-l-cysteine (NAC) reduced ROS generation and DNA DSBs, inhibited apoptosis, and increased cell viability in AFG1-treated cells. Furthermore, we found AFG1 activated ROS-mediated JNK and p38 pathways to induce cell apoptosis in A549 cells. In conclusion, our results indicate that AFG1 induces oxidative DNA damage and triggers apoptosis through ROS-mediated JNK and p38 signaling pathways in A549 cells, which may contribute to AFG1-induced AT-II cell damage.

Ling-xiao Xing – One of the best experts on this subject based on the ideXlab platform.

  • High mobility group box-1 protects against Aflatoxin G1-induced pulmonary epithelial cell damage in the lung inflammatory environment.
    Toxicology letters, 2020
    Co-Authors: Lifei Kang, Ling-xiao Xing, Chunping Liu, Ningfei Guo, Xiaoyi Liu, Xiuqing Wang, Wenli Guo, Shelly M. Xie, Xianghong Zhang

    Abstract:

    Abstract Aflatoxin G1 (AFG1) is a member of the carcinogenic Aflatoxin family. Our previous studies indicated that oral administration of AFG1 caused tumor necrosis factor (TNF)-α-dependent inflammation that enhanced oxidative DNA damage in alveolar epithelial cells, which may be related to AFG1-induced lung carcinogenesis. High mobility group box-1 (HMGB1) is a nuclear DNA-binding protein; the intracellular and extracellular roles of HMGB1 have been shown to contribute to DNA repair and sterile inflammation. The role of HMGB1 in DNA damage in an Aflatoxin-induced lung inflammatory environment was investigated in this study. Upregulation of HMGB1, TLR2, and RAGE was observed in AFG1-induced lung inflamed tissues and adenocarcinoma. Blocking AFG1-induced inflammation by neutralization of TNF-α inhibited the upregulation of HMGB1 in mouse lung tissues, suggesting that AFG1-induced TNF-α-dependent inflammation regulated HMGB1 expression. In the in vitro human pulmonary epithelial cell line model, Beas-2b, AFG1 directly enhanced the cytosolic translocation of HMGB1 and its extracellular secretion. The addition of extracellular soluble HMGB1 protected AFG1-induced DNA damage through the TLR2/NF-κB pathway in Beas-2b cells. In addition, blockade of endogenous HMGB1 by siRNA significantly enhanced AFG1-induced damage. Thus, our findings showed that both extracellularly-released and nuclear and cytosolic HMGB1 could protect the cell from AFG1-induced cell damage in a TNF-α-dependent lung inflammatory environment.

  • Enhanced Phenotypic Alterations of Alveolar Type II Cells in Response to Aflatoxin G1-Induced Lung Inflammation
    Journal of cellular physiology, 2015
    Co-Authors: Haitao Shen, Chunping Liu, Peilu Shao, Yuan Wang, Juan Wang, Ziqiang Tian, Xin Zhao, Ling-xiao Xing

    Abstract:

    Recently, we discovered that Aflatoxin G1 (AFG1) induces chronic lung inflammatory responses, which may contribute to lung tumorigenesis in Balb/C mice. The cancer cells originate from alveolar type II cells (AT-II cells). The activated AT-II cells express high levels of MHC-II and COX-2, may exhibit altered phenotypes, and likely inhibit antitumor immunity by triggering regulatory T cells (Tregs). However, the mechanism underlying phenotypic alterations of AT-II cells caused by AFG1-induced inflammation remains unknown. In this study, increased MHC-II expression in alveolar epithelium was observed and associated with enhanced Treg infiltration in mouse lung tissues with AFG1-induced inflammation. This provides a link between phenotypically altered AT-II cells and Treg activity in the AFG1-induced inflammatory microenvironment. AFG1-activated AT-II cells underwent phenotypic maturation since AFG1 upregulated MHC-II expression on A549 cells and primary human AT-II cells in vitro. However, mature AT-II cells may exhibit insufficient antigen presentation, which is necessary to activate effector T cells, due to the absence of CD80 and CD86. Furthermore, we treated A549 cells with AFG1 and TNF-α together to mimic an AFG1-induced inflammatory response in vitro, and we found that TNF-α and AFG1 coordinately enhanced MHC-II, CD54, COX-2, IL-10, and TGF-β expression levels in A549 cells compared to AFG1 alone. The phenotypic alterations of A549 cells in response to the combination of TNF-α and AFG1 were mainly regulated by TNF-α-mediated induction of the NF-κB pathway. Thus, enhanced phenotypic alterations of AT-II cells were induced in response to AFG1-induced inflammation. Thus, AT-II cells are likely to suppress anti-tumor immunity by triggering Treg activity. J. Cell. Physiol. 230: 1199–1211, 2015. © 2014 Wiley Periodicals, Inc., A Wiley Company

  • Oral administration of Aflatoxin G1 induces chronic alveolar inflammation associated with lung tumorigenesis
    Toxicology letters, 2014
    Co-Authors: Chunping Liu, Xia Yan, Ling-xiao Xing, Haitao Shen, Peilu Shao, Athena M. Soulika, Xinxing Meng, Xianghong Zhang

    Abstract:

    Abstract Our previous studies showed oral gavage of Aflatoxin G1 (AFG1) induced lung adenocarcinoma in NIH mice. We recently found that a single intratracheal administration of AFG1 caused chronic inflammatory changes in rat alveolar septum. Here, we examine whether oral gavage of AFG1 induces chronic lung inflammation and how it contributes to carcinogenesis. We evaluated chronic lung inflammatory responses in Balb/c mice after oral gavage of AFG1 for 1, 3 and 6 months. Inflammatory responses were heightened in the lung alveolar septum, 3 and 6 months after AFG1 treatment, evidenced by increased macrophages and lymphocytes infiltration, up-regulation of NF-κB and p-STAT3, and cytokines production. High expression levels of superoxide dismutase (SOD-2) and hemoxygenase-1 (HO-1), two established markers of oxidative stress, were detected in alveolar epithelium of AFG1-treated mice. Promoted alveolar type II cell (AT-II) proliferation in alveolar epithelium and angiogenesis, as well as increased COX-2 expression were also observed in lung tissues of AFG1-treated mice. Furthermore, we prolonged survival of the mice in the above model for another 6 months to examine the contribution of AFG1-induced chronic inflammation to lung tumorigenesis. Twelve months later, we observed that AFG1 induced alveolar epithelial hyperplasia and adenocarcinoma in Balb/c mice. Up-regulation of NF-κB, p-STAT3, and COX-2 was also induced in lung adenocarcinoma, thus establishing a link between AFG1-induced chronic inflammation and lung tumorigenesis. This is the first study to show that oral administration of AFG1 could induce chronic lung inflammation, which may provide a pro-tumor microenvironment to contribute to lung tumorigenesis.

Haitao Shen – One of the best experts on this subject based on the ideXlab platform.

  • Enhanced Phenotypic Alterations of Alveolar Type II Cells in Response to Aflatoxin G1-Induced Lung Inflammation
    Journal of cellular physiology, 2015
    Co-Authors: Haitao Shen, Chunping Liu, Peilu Shao, Yuan Wang, Juan Wang, Ziqiang Tian, Xin Zhao, Ling-xiao Xing

    Abstract:

    Recently, we discovered that Aflatoxin G1 (AFG1) induces chronic lung inflammatory responses, which may contribute to lung tumorigenesis in Balb/C mice. The cancer cells originate from alveolar type II cells (AT-II cells). The activated AT-II cells express high levels of MHC-II and COX-2, may exhibit altered phenotypes, and likely inhibit antitumor immunity by triggering regulatory T cells (Tregs). However, the mechanism underlying phenotypic alterations of AT-II cells caused by AFG1-induced inflammation remains unknown. In this study, increased MHC-II expression in alveolar epithelium was observed and associated with enhanced Treg infiltration in mouse lung tissues with AFG1-induced inflammation. This provides a link between phenotypically altered AT-II cells and Treg activity in the AFG1-induced inflammatory microenvironment. AFG1-activated AT-II cells underwent phenotypic maturation since AFG1 upregulated MHC-II expression on A549 cells and primary human AT-II cells in vitro. However, mature AT-II cells may exhibit insufficient antigen presentation, which is necessary to activate effector T cells, due to the absence of CD80 and CD86. Furthermore, we treated A549 cells with AFG1 and TNF-α together to mimic an AFG1-induced inflammatory response in vitro, and we found that TNF-α and AFG1 coordinately enhanced MHC-II, CD54, COX-2, IL-10, and TGF-β expression levels in A549 cells compared to AFG1 alone. The phenotypic alterations of A549 cells in response to the combination of TNF-α and AFG1 were mainly regulated by TNF-α-mediated induction of the NF-κB pathway. Thus, enhanced phenotypic alterations of AT-II cells were induced in response to AFG1-induced inflammation. Thus, AT-II cells are likely to suppress anti-tumor immunity by triggering Treg activity. J. Cell. Physiol. 230: 1199–1211, 2015. © 2014 Wiley Periodicals, Inc., A Wiley Company

  • Oral administration of Aflatoxin G1 induces chronic alveolar inflammation associated with lung tumorigenesis
    Toxicology letters, 2014
    Co-Authors: Chunping Liu, Xia Yan, Ling-xiao Xing, Haitao Shen, Peilu Shao, Athena M. Soulika, Xinxing Meng, Xianghong Zhang

    Abstract:

    Abstract Our previous studies showed oral gavage of Aflatoxin G1 (AFG1) induced lung adenocarcinoma in NIH mice. We recently found that a single intratracheal administration of AFG1 caused chronic inflammatory changes in rat alveolar septum. Here, we examine whether oral gavage of AFG1 induces chronic lung inflammation and how it contributes to carcinogenesis. We evaluated chronic lung inflammatory responses in Balb/c mice after oral gavage of AFG1 for 1, 3 and 6 months. Inflammatory responses were heightened in the lung alveolar septum, 3 and 6 months after AFG1 treatment, evidenced by increased macrophages and lymphocytes infiltration, up-regulation of NF-κB and p-STAT3, and cytokines production. High expression levels of superoxide dismutase (SOD-2) and hemoxygenase-1 (HO-1), two established markers of oxidative stress, were detected in alveolar epithelium of AFG1-treated mice. Promoted alveolar type II cell (AT-II) proliferation in alveolar epithelium and angiogenesis, as well as increased COX-2 expression were also observed in lung tissues of AFG1-treated mice. Furthermore, we prolonged survival of the mice in the above model for another 6 months to examine the contribution of AFG1-induced chronic inflammation to lung tumorigenesis. Twelve months later, we observed that AFG1 induced alveolar epithelial hyperplasia and adenocarcinoma in Balb/c mice. Up-regulation of NF-κB, p-STAT3, and COX-2 was also induced in lung adenocarcinoma, thus establishing a link between AFG1-induced chronic inflammation and lung tumorigenesis. This is the first study to show that oral administration of AFG1 could induce chronic lung inflammation, which may provide a pro-tumor microenvironment to contribute to lung tumorigenesis.

  • Aflatoxin G1-induced oxidative stress causes DNA damage and triggers apoptosis through MAPK signaling pathway in A549 cells.
    Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 2013
    Co-Authors: Haitao Shen, Jun-ling Wang, Xia Yan, Ling-xiao Xing, Jing Liu, Yuan Wang, Hongguang Lian, Juan Wang, Xianghong Zhang

    Abstract:

    Our previous studies showed that Aflatoxin G1 (AFG1) could induce lung adenocarcinoma, and that the cancer cells originated from alveolar type II cells (AT-II cells). Recently, we found AFG1 induced structural impairment in rat AT-II cells, which may account for an early event in lung tumorigenesis. However, the mechanism of AFG1-induced AT-II cell damage remains unclear. DNA damage and apoptosis induced by oxidative stress are well accepted causes of cell damage. Thus, we explore whether AFG1 activates the reactive oxygen species (ROS)/MAPK/apoptosis pathway to cause cell damage in human AT-II cells like the cell line (A549). We found AFG1 induced oxidative stress by increasing ROS generation and caused DNA double-strand breaks (DSBs) by up-regulating γH2AX expression. AFG1 also triggered apoptosis in A549 cells by regulating Fas/FasL, caspase-8, Bax, Bcl-2, and activating caspase-3. Pre-treatment with antioxidant n-acetyl-l-cysteine (NAC) reduced ROS generation and DNA DSBs, inhibited apoptosis, and increased cell viability in AFG1-treated cells. Furthermore, we found AFG1 activated ROS-mediated JNK and p38 pathways to induce cell apoptosis in A549 cells. In conclusion, our results indicate that AFG1 induces oxidative DNA damage and triggers apoptosis through ROS-mediated JNK and p38 signaling pathways in A549 cells, which may contribute to AFG1-induced AT-II cell damage.