Decoding NADPH oxidase 4 expression in human tumors
Jennifer L. Meitzler,
Hala R. Makhlouf,
Smitha Antony,
Yongzhong Wu,
Donna Butcher,
Guojian Jiang,
Agnes Juhasz,
Jiamo Lu,
Iris Dahan,
Pidder Jansen-Dürr,
Haymo Pircher,
Ajay M. Shah,
Krishnendu Roy,
James H. Doroshow
Affiliations
Jennifer L. Meitzler
Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
Hala R. Makhlouf
Division of Cancer Treatment and Diagnosis, National Cancer Institute, NIH, Bethesda, MD 20892, USA
Smitha Antony
Division of Cancer Treatment and Diagnosis, National Cancer Institute, NIH, Bethesda, MD 20892, USA
Yongzhong Wu
Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
Donna Butcher
Pathology/Histotechnology Laboratory, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, NIH, Frederick, MD 21702, USA
Guojian Jiang
Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
Agnes Juhasz
Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
Jiamo Lu
Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
Iris Dahan
Division of Cancer Treatment and Diagnosis, National Cancer Institute, NIH, Bethesda, MD 20892, USA
Pidder Jansen-Dürr
Institute for Biomedical Aging Research and Center for Molecular Biosciences Innsbruck (CMBI), Universität Innsbruck, 6020 Innsbruck, Austria
Haymo Pircher
Institute for Biomedical Aging Research and Center for Molecular Biosciences Innsbruck (CMBI), Universität Innsbruck, 6020 Innsbruck, Austria
Ajay M. Shah
King's College London British Heart Foundation Centre, Cardiovascular Division, James Black Centre, London SE5 9NU, United Kingdom
Krishnendu Roy
Division of Cancer Treatment and Diagnosis, National Cancer Institute, NIH, Bethesda, MD 20892, USA
James H. Doroshow
Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
NADPH oxidase 4 (NOX4) is a redox active, membrane-associated protein that contributes to genomic instability, redox signaling, and radiation sensitivity in human cancers based on its capacity to generate H2O2 constitutively. Most studies of NOX4 in malignancy have focused on the evaluation of a small number of tumor cell lines and not on human tumor specimens themselves; furthermore, these studies have often employed immunological tools that have not been well characterized. To determine the prevalence of NOX4 expression across a broad range of solid tumors, we developed a novel monoclonal antibody that recognizes a specific extracellular region of the human NOX4 protein, and that does not cross-react with any of the other six members of the NOX gene family. Evaluation of 20 sets of epithelial tumors revealed, for the first time, high levels of NOX4 expression in carcinomas of the head and neck (15/19 patients), esophagus (12/18 patients), bladder (10/19 patients), ovary (6/17 patients), and prostate (7/19 patients), as well as malignant melanoma (7/15 patients) when these tumors were compared to histologically-uninvolved specimens from the same organs. Detection of NOX4 protein upregulation by low levels of TGF-β1 demonstrated the sensitivity of this new probe; and immunofluorescence experiments found that high levels of endogenous NOX4 expression in ovarian cancer cells were only demonstrable associated with perinuclear membranes. These studies suggest that NOX4 expression is upregulated, compared to normal tissues, in a well-defined, and specific group of human carcinomas, and that its expression is localized on intracellular membranes in a fashion that could modulate oxidative DNA damage.
