Nrf2-deficiency creates a responsive microenvironment for metastasis to the lung.

The Nrf2 transcription factor is crucial for regulating the cellular defense against various carcinogens. However, relationship between host Nrf2 and cancer metastasis remains unexplored. To address this issue, we examined susceptibility of Nrf2-deficient mice to pulmonary cancer metastasis following implantation of the mouse Lewis lung carcinoma (3LL) cell line. Nrf2-deficient mice reproducibly exhibited a higher number of pulmonary metastatic nodules than wild-type mice did. The lung and bone marrow (BM) of cancer-bearing Nrf2-deficient mice contained increased numbers of inflammatory cells, including myeloid-derived suppressor cells (MDSCs), a potent population of immunosuppressive cells. MDSCs can attenuate CD8(+) T-cell immunity through modification of the T-cell receptor complex exploiting reactive oxygen species (ROS). MDSCs of Nrf2-deficient mice retained elevated levels of ROS relative to wild-type mice. BM transplantation experiments revealed functional disturbance in the hematopoietic and immune systems of Nrf2-deficient mice. Wild-type recipient mice with Nrf2-deficient BM cells showed increased levels of lung metastasis after cancer cell inoculation. These mice exhibited high-level accumulation of ROS in MDSCs, which showed very good coincidence to the decrease of splenic CD8(+) T-cells. In contrast, Keap1-knockdown mutant mice harboring high-level Nrf2 expression displayed increased resistance against the cancer cell metastasis to the lung, accompanied by a decrease in ROS in the MDSCs fraction. Our results thus reveal a novel function for Nrf2 in the prevention of cancer metastasis, presumably by its ability to preserve the redox balance in the hematopoietic and immune systems.

[1]  P. Sinha,et al.  Myeloid-Derived Suppressor Cells: Linking Inflammation and Cancer 1 , 2009, The Journal of Immunology.

[2]  S. Hirohashi,et al.  Genetic alteration of Keap1 confers constitutive Nrf2 activation and resistance to chemotherapy in gallbladder cancer. , 2008, Gastroenterology.

[3]  D. Foell,et al.  Proinflammatory S100 Proteins Regulate the Accumulation of Myeloid-Derived Suppressor Cells1 , 2008, The Journal of Immunology.

[4]  I. Hyodo,et al.  Ursodeoxycholic acid stimulates Nrf2-mediated hepatocellular transport, detoxification, and antioxidative stress systems in mice. , 2008, American journal of physiology. Gastrointestinal and liver physiology.

[5]  Tsutomu Ohta,et al.  Cancer related mutations in NRF2 impair its recognition by Keap1-Cul3 E3 ligase and promote malignancy , 2008, Proceedings of the National Academy of Sciences.

[6]  A. Kong,et al.  Increased Susceptibility of Nrf2 Knockout Mice to Colitis-Associated Colorectal Cancer , 2008, Cancer Prevention Research.

[7]  N. Ferrara,et al.  Refractoriness to antivascular endothelial growth factor treatment: role of myeloid cells. , 2008, Cancer research.

[8]  A. Nel,et al.  Nrf2 activation by sulforaphane restores the age-related decrease of T(H)1 immunity: role of dendritic cells. , 2008, The Journal of allergy and clinical immunology.

[9]  D. Gabrilovich,et al.  Tumor escape mechanism governed by myeloid-derived suppressor cells. , 2008, Cancer research.

[10]  S. Hirohashi,et al.  Loss of Keap1 function activates Nrf2 and provides advantages for lung cancer cell growth. , 2008, Cancer research.

[11]  S. Hirohashi,et al.  Loss of Keap 1 Function Activates Nrf 2 and Provides Advantages for Lung Cancer Cell Growth , 2008 .

[12]  A. Kong,et al.  Increased Susceptibility of Nrf 2 Knockout Mice to Colitis-Associated Colorectal Cancer , 2008 .

[13]  M. Fishman,et al.  Mechanism of all-trans retinoic acid effect on tumor-associated myeloid-derived suppressor cells. , 2007, Cancer research.

[14]  H. Akaza,et al.  Nrf2 and p53 cooperatively protect against BBN-induced urinary bladder carcinogenesis. , 2007, Carcinogenesis.

[15]  Justina McEvoy,et al.  Subcellular localization and cytoplasmic complex status of endogenous Keap1 , 2007, Genes to cells : devoted to molecular & cellular mechanisms.

[16]  K. Gupta,et al.  Altered recognition of antigen is a mechanism of CD8+ T cell tolerance in cancer , 2007, Nature Medicine.

[17]  J. Herman,et al.  Dysfunctional KEAP1–NRF2 Interaction in Non-Small-Cell Lung Cancer , 2006, PLoS medicine.

[18]  V. Raman,et al.  Noninvasive optical tracking of red fluorescent protein-expressing cancer cells in a model of metastatic breast cancer. , 2006, Neoplasia.

[19]  A. Conney,et al.  Inhibition of 7,12-dimethylbenz(a)anthracene-induced skin tumorigenesis in C57BL/6 mice by sulforaphane is mediated by nuclear factor E2-related factor 2. , 2006, Cancer research.

[20]  H. Kasai,et al.  Oxidative DNA damage: mechanisms and significance in health and disease. , 2006, Antioxidants & redox signaling.

[21]  Masayuki Yamamoto,et al.  Nrf2 is a critical regulator of the innate immune response and survival during experimental sepsis. , 2006, The Journal of clinical investigation.

[22]  Tsutomu Ohta,et al.  Structural basis for defects of Keap1 activity provoked by its point mutations in lung cancer. , 2006, Molecular cell.

[23]  K. Itoh,et al.  Transcription Factor Nrf2 Plays a Pivotal Role in Protection against Elastase-Induced Pulmonary Inflammation and Emphysema1 , 2005, The Journal of Immunology.

[24]  K. Itoh,et al.  Transcription Factor Nrf 2 Plays a Pivotal Role in Protection against Elastase-Induced Pulmonary Inflammation and Emphysema 1 , 2005 .

[25]  Masayuki Yamamoto,et al.  Oxidative Stress Sensor Keap1 Functions as an Adaptor for Cul3-Based E3 Ligase To Regulate Proteasomal Degradation of Nrf2 , 2004, Molecular and Cellular Biology.

[26]  J. D. Engel,et al.  Small Maf proteins serve as transcriptional cofactors for keratinocyte differentiation in the Keap1-Nrf2 regulatory pathway. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[27]  C. B. Pickett,et al.  Regulatory mechanisms controlling gene expression mediated by the antioxidant response element. , 2003, Annual review of pharmacology and toxicology.

[28]  K. Itoh,et al.  Keap1 regulates both cytoplasmic‐nuclear shuttling and degradation of Nrf2 in response to electrophiles , 2003, Genes to cells : devoted to molecular & cellular mechanisms.

[29]  K. Itoh,et al.  Accelerated DNA adduct formation in the lung of the Nrf2 knockout mouse exposed to diesel exhaust. , 2001, Toxicology and applied pharmacology.

[30]  M. Kwak,et al.  Sensitivity to carcinogenesis is increased and chemoprotective efficacy of enzyme inducers is lost in nrf2 transcription factor-deficient mice , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[31]  K. Itoh,et al.  An Nrf2/small Maf heterodimer mediates the induction of phase II detoxifying enzyme genes through antioxidant response elements. , 1997, Biochemical and biophysical research communications.

[32]  N. Kumano,et al.  Conversion of Lewis lung carcinoma into ascitic form. , 1989, Oncology.

[33]  J. Kyhse-Andersen.  Electroblotting of multiple gels: a simple apparatus without buffer tank for rapid transfer of proteins from polyacrylamide to nitrocellulose. , 1984, Journal of biochemical and biophysical methods.

[34]  R. Roeder,et al.  Accurate transcription initiation by RNA polymerase II in a soluble extract from isolated mammalian nuclei. , 1983, Nucleic acids research.

[35]  I. Fidler,et al.  In vitro selection of murine B16 melanoma variants with enhanced tissue-invasive properties. , 1980, Cancer research.

[36]  G. Stoner,et al.  Test for carcinogenicity of food additives and chemotherapeutic agents by the pulmonary tumor response in strain A mice. , 1973, Cancer research.