Caveolin-1 regulates lung cancer stem-like cell induction and p53 inactivation in carbon nanotube-driven tumorigenesis
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Sudjit Luanpitpong1,2, Liying Wang3, Todd A. Stueckle3, William Tse2, Yi Charlie Chen4 and Yon Rojanasakul1,2
1 Pharmaceutical and Pharmacological Sciences Program, West Virginia University, WV 26506, USA
2 Mary Babb Randolph Cancer Center, West Virginia University, WV 26506, USA
3 Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
4 College of Science, Technology and Mathematics, Alderson Broaddus University, Philippi, WV 26416, USA
Sudjit Luanpitpong, email:
Keywords: caveolin-1, p53, lung, cancer stem-like cells, tumorigenesis, carbon nanotubes.
Received: March 22, 2014 Accepted: May 7, 2014 Published: May 8, 2014
Cancer stem cells (CSCs) may represent targets for carcinogenic initiation by chemical and environmental agents. Recent studies have raised a concern over the potential carcinogenicity of carbon nanotubes (CNTs), one of the most commonly used engineered nanomaterials with asbestos-like properties. Here, we show that chronic (6-month) exposure of human lung epithelial cells to single-walled (SW) CNTs at the workplace-relevant concentration induced an emergence of lung CSCs, as indicated by the induction of CSC tumor spheres and side population (SP). These CSCs, which were found to overexpress tumor promoter caveolin-1 (Cav-1), displayed aggressive cancer phenotypes of apoptosis resistance and enhanced cell invasion and migration compared with their non-CSC counterpart. Using gene manipulation strategies, we reveal for the first time that Cav-1 plays an essential role in CSC regulation and aggressiveness of SWCNT-transformed cells partly through p53 dysregulation, consistent with their suggested role by microarray and gene ontology analysis. Cav-1 not only promoted tumorigenesis in a xenograft mouse model but also metastasis of the transformed cells to neighboring tissues. Since CSCs are crucial to the initiation and early development of carcinogenesis, our findings on CSC induction by SWCNTs and Cav-1 could aid in the early detection and risk assessment of the disease.
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