Impaired lysosomal activity mediated autophagic flux disruption by graphite carbon nanofibers induce apoptosis in human
- PDF / 9,733,131 Bytes
- 25 Pages / 595.276 x 790.866 pts Page_size
- 79 Downloads / 143 Views
RESEARCH
Open Access
Impaired lysosomal activity mediated autophagic flux disruption by graphite carbon nanofibers induce apoptosis in human lung epithelial cells through oxidative stress and energetic impairment Sandeep Mittal1,2, Pradeep Kumar Sharma3, Ratnakar Tiwari4, Raja Gopal Rayavarapu1,2, Jai Shankar5, Lalit Kumar Singh Chauhan5 and Alok Kumar Pandey1,2*
Abstract Background: Graphite carbon nanofibers (GCNF) have emerged as a potential alternative of carbon nanotubes (CNT) for various biomedical applications due to their superior physico-chemical properties. Therefore in-depth understanding of the GCNF induced toxic effects and underlying mechanisms in biological systems is of great interest. Currently, autophagy activation by nanomaterials is recognized as an emerging toxicity mechanism. However, the association of GCNF induced toxicity with this form of cell death is largely unknown. In this study, we have assessed the possible mechanism; especially the role of autophagy, underlying the GCNF induced toxicity. Methods: Human lung adenocarcinoma (A549) cells were exposed to a range of GCNF concentrations and various cellular parameters were analyzed (up to 48 h). Transmission electron microscopy, immunofluorescent staining, western blot and quantitative real time PCR were performed to detect apoptosis, autophagy induction, lysosomal destabilization and cytoskeleton disruption in GCNF exposed cells. DCFDA assay was used to evaluate the reactive oxygen species (ROS) production. Experiments with N-acetyl-L-cysteine (NAC), 3-methyladenine (3-MA) and LC3 siRNA was carried out to confirm the involvement of oxidative stress and autophagy in GCNF induced cell death. Comet assay and micronucleus (MN) assay was performed to assess the genotoxicity potential. Results: In the present study, GCNF was found to induce nanotoxicity in human lung cells through autophagosomes accumulation followed by apoptosis via intracellular ROS generation. Mechanistically, impaired lysosomal function and cytoskeleton disruption mediated autophagic flux blockade was found to be the major cause of accumulation rather than autophagy induction which further activates apoptosis. The whole process was in line with the increased ROS level and their pharmacological inhibition leads to mitigation of GCNF induced cell death. Moreover the inhibition of autophagy attenuates apoptosis indicating the role of autophagy as cell death process. GCNF was also found to induce genomic instability. (Continued on next page)
* Correspondence: [email protected]; [email protected] 1 Academy of Scientific and Innovative Research (AcSIR), CSIR-IITR Campus, Lucknow, India 2 Nanomaterials Toxicology Laboratory, Nanotherapeutics and Nanomaterial Toxicology Group, CSIR - Indian Institute of Toxicology Research (CSIR - IITR), Vishvigyan Bhawan, 31, Mahatma Gandhi Marg, Lucknow 226001, Uttar Pradesh, India Full list of author information is available at the end of the article © The Author(s). 2017 Open Access This article is distributed under the terms o
Data Loading...
