Published ahead of print on September 15, 2005, doi:10.1165/rcmb.2005-0213OC
© 2005 American Thoracic Society DOI: 10.1165/rcmb.2005-0213OC Molecular Mechanisms of Hexavalent Chromium–Induced Apoptosis in Human Bronchoalveolar CellsDepartment of Integrated Medical Oncology, Laboratory of Translational Research B (Lung Cancer), National Cancer Institute, Genoa; Department of Biology, University of Genoa, Genoa; Department of Surgical Science, Division of General Thoracic Surgery, Catholic University, Rome; Clinical Respiratory and Pathology Translational Laboratory, and Department of Internal Medicine Sciences, Istituto Ricerca Cura Carattere Scientifico San Raffaele, Rome; and Center of Thoracic Surgery, University of Insubria, Varese, Italy Correspondence and requests for reprints should be addressed to Dr. Patrizia Russo, Department of Integrated Medical Oncology (DOMI), Laboratory of Translational Research B (Lung Cancer), National Cancer Institute, Largo Rosanna Benzi 10, I-16132 Genoa, Italy. E-mail: patrizia.russo{at}istge.it Hexavalent chromium (Cr[VI]) is classified by the International Agency for Research on Cancer as a group I carcinogen. Although the U.S. Occupational Safety and Health Administration was obliged to reduce the permissible exposure limit (PEL), it was reported that U.S. workers continue to be exposed to dangerously high Cr(VI) levels. In this study, we examined the role of p53 and target genes in a bronchoalveolar carcinoma isogenic cell line system and in primary human bronchial epithelial cells. p53-Negative parental H358 cell line, the same line in which the wild-type p53 expression vector (pC53-SN3) was introduced, and cells obtained from biopsies of human bronchus were exposed to chromate. Induction of DNA strand breaks were evaluated by alkaline elution assay, and apoptosis was analyzed by gel ladder, annexin V-PI staining, and ELISA, whereas p53 and target genes were evaluated by Western blots. Although Cr(VI) induced DNA strand breaks in both H358 cell clones, apoptosis was present only in the p53-transfected cells (H358p53+/+). In these cells, Cr(VI)-induced apoptosis is mediated by p53 upregulation of p53-upregulated modulator of apoptosis (PUMA), BAX translocation to mitochondria, cytochrome c release, and caspase-3 activation. In primary human bronchial epithelial cells expressing functional p53, Cr(VI) induced expression of PUMA and Noxa, which promote apoptosis through BAX. This result establishes p53 as the "necessary" player in Cr(VI)-induced apoptosis. To the best of our knowledge, this is the first report indicating strict correlation of Cr(VI) apoptosis to PUMA induction on primary human bronchoalveolar cells in short-term cultures.
Key Words: apoptosis • bronchial epithelial cells • hexavalent chromium • p53 • PUMA This article has been cited by other articles:
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