Multi-walled carbon nanotubes induce oxidative stress and apoptosis in human lung cancer cell line-A549

Abstract

Multi-walled carbon-nanotubes (MWCNTs)-induced apoptotic changes were studied in human lung epithelium cell line-A549. Non-cytotoxic doses of MWCNTs were identified using tetrazolium bromide salt (MTT) and lactate dehydrogenase (LDH) release assays. Cells were exposed to MWCNTs (0.5–100 μg/ml) for 6–72 h. Internalization and characterization of CNTs was performed by electron microscopy. Apoptotic changes were estimated by nuclear condensation, DNA laddering, and confirmed by expression of associated markers: p⁵³, p^21WAF1/CIP1, Bax, Bcl₂ and activated caspase-3. MWCNTs induced the production of reactive oxygen species and malondialdehyde along with significant decrease in the activity of catalase and glutathione. MWCNTs-induced ROS generation was found not to be associated with the mitochondrial activity. In general, the changes were significant at 10 and 50 μg/ml only. Results indicate the involvement of oxidative stress and apoptosis in A549 cells exposed to MWCNTs. Our studies provide insights of the mechanisms involved in MWCNTs-induced apoptosis at cellular level.

Keywords::

• A549
• apoptosis
• genotoxicity
• oxidative stress
• MWCNTs
• electron microscopy

Acknowledgements

Authors are grateful to the Director, Indian Institute of Toxicology Research, Lucknow, India, for his keen interest in the study. Financial support by Council of Scientific and Industrial Research, New Delhi, (SIP-08) is acknowledged. The technical support by Mr Rajesh Mishra is also acknowledged.

Declaration of interest : The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.