Reactive nitrogen species control apoptosis and autophagy in K562 cells: implication of TAp73α induction in controlling autophagy

Abstract

The biological outcome of nitric oxide (NO) and reactive nitrogen species (RNS) in regulating pro survival and pro death autophagic pathways still demand further investigation. In the present study, we investigated the effect of nitrosative stress in K562 cells using NO donor compound DETA-NONOate, peroxynitrite, and SIN-1. Exposure to NO, peroxynitrite, and SIN-1 caused decrease in K562 cell survival. NO induced autophagy but not apoptosis or necrosis in K562 cells. In contrast, peroxynitrite and SIN-1 treatment induced apoptosis in K562 cells. Surprisingly, inhibition of autophagic response using 3-methyladenine led to the induction of apoptosis in K562 cells. Increase in 5’adenosine monophosphate-activated protein kinase (AMPK) phosphorylation was only observed in the presence of NO donor indicated that AMPK was crucial to induce autophagy in K562 cells. We for the first time discovered a novel role of p73 in autophagy induction under nitrosative stress in K562 cells. TAp73α was only induced upon exposure to NO but not in the presence of peroxynitrite. Reduced glutathione (GSH)/oxidised glutathione (GSSG) ratio remained unaltered upon NO exposure. Our data suggest a complex network of interaction and cross regulations between NO and p73. These data open a new path for therapies based on the abilities of RNS to induce autophagy-mediated cell death.

Keywords:

• Nitric oxide
• nitrosative stress
• cellular redox status
• autophagy
• apoptosis
• CML-K562 cell line
• TAp73α

Acknowledgements

The authors would like to thank Dr Santu Bandopadhyay, Scientist, Indian Institute of Chemical Biology (IICB) for providing K562 cell line. We thank Dr Debajit Bhowmik (at the University of Calcutta-BD Flow Cytometry Facility at CRNN, University of Calcutta) for his help in interpreting the flow cytometry data. The consumable for the entire work was supported by DBT, government offices of India, Grant BT/PR12551/BRB/10/02/2009 dated 3 September 2010. We thank CRNN, University of Calcutta, DBT-IPLS, UPE, DAE, and UGC CAS Phase II Govt. of India for providing their infrastructural facility, UGC, government offices of India, Grant no. UGC/787/JRF (Up gradation) dated 22.05.2014 for providing fellowship to S.D., CSIR, government offices of India, grant No. 09/028 (0945)/2015-EMR-I dated 10.07.2015 for providing fellowship to S.C. and DST-PURSE programme, government offices of India for providing fellowship to C.P. the funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Disclosure statement

The authors declare that they have no competing interests.