Isoniazid-induced apoptosis in HepG2 cells: Generation of oxidative stress and Bcl-2 down-regulation

Abstract

Isoniazid (INH) is a first-line antibiotic used in the treatment of infections caused by Mycobacterium tuberculosis. However it has a serious limitation of being hepatotoxic. Delineating the mechanism underlying INH-induced hepatotoxicity may be beneficial in devising ways to counteract its toxic manifestations. Studies in human hepatoma HepG2 cells have indicated that INH exposure causes induction of apoptosis. This study was aimed at identifying the key components/pathways of the INH-induced apoptotic pathway using HepG2 cells. HepG2 cells were exposed to increasing concentrations of INH (6.5, 13, 26, and 52 mM). Hydrogen peroxide (0.3 mM) served as positive control. After incubating for specific time intervals cells were harvested and evidences of cytotoxicity, oxidative stress, and apoptosis were sought. The findings indicated that INH exposure causes increased ROS generation along with alteration in levels of enzymatic antioxidants such as Superoxide dismutase, Catalase, and Glucose-6-Phosphate dehydrogenase. Altered Bcl-2/Bax content, cytochrome-c translocation, caspase activation, and DNA fragmentation emphasized involvement of apoptosis.

Keywords::

• Apoptosis
• hepatotoxicity
• oxidative stress
• reactive oxygen species

Acknowledgements

We thank the Director of the Central Drug Research Institute and Head, Toxicology for facilities and support. We are grateful to Dr A. Balapure and Dr R. Sharma for providing HepG2 cell line. The authors extend thanks to Dr M. Abbas and Mr M. Srivastava for performing statistical analysis.

Declaration of interest

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