Molecular and Cellular Biochemistry

, Volume 444, Issue 1–2, pp 207–218 | Cite as

Radioresistant Sf9 insect cells readily undergo an intrinsic mode of apoptosis in response to histone deacetylase (HDAC) inhibition

  • Jyoti Swaroop Kumar
  • Shubhankar Suman
  • Sudhir Chandna


Insect cell lines have been utilized as an important higher eukaryotic model system to decipher stress responses and cell death mechanisms. Lepidopteran Sf9 cells (derived from the ovaries of Spodoptera frugiperda) display nearly 100 times higher resistance to ionizing radiation in contrast to mammalian cells, which is partly contributed by an unusually high HDAC activity. However, their response to HDAC inhibition remains to be evaluated. In the present study, the effects of HDAC inhibitor (NaBt) on Sf9 cellular/nuclear morphology, cell cycle progression, DNA damage/repair, redox status, and mitochondrial perturbations were evaluated. NaBt-induced apoptosis was evident at 18 h in Sf9 cells at 2 mM concentration, primarily through mitochondrial induction of oxidative stress and subsequent DNA damage. Cell cycle analysis revealed appearance of sub-G1 DNA content at 12 h onwards and DNA fragmentation by 18 h. Initial few hours of treatment caused significant loss in MMP through oxidation of mitochondrial inner membrane protein, i.e., cardiolipin. HDAC inhibition-mediated apoptosis was associated with increased Bax/Bcl2 ratio, mitochondrial cytochrome-c release, and caspase-3 activation. The study thus infers that Sf9 cells, which can withstand very high radiation doses, are quite sensitive to the increase in the chromatin acetylation levels. In addition, HDAC inhibition also sensitized Sf9 cells to radiation-induced DNA damage, further corroborating our recent finding that chromatin compactness contributes significantly to their radioresistance. Therefore, the study demonstrates prominence of prevailing DNA/chromatin protective mechanisms in Lepidopteran insect cells.


Apoptosis Sf9 cells Reactive oxygen species DNA damage Sodium butyrate HDAC inhibitor 



Spodoptera frugiperda-9


Reactive oxygen species


Mitochondrial membrane potential


Sodium butyrate


Histone deacetylases



This study was funded through DRDO (Defence Research and Development Organization) Grant# INM-311.1.5. JSK received research fellowship/associateship from Indian Council of Medical Research (ICMR)/Defence Research and Development Organization (DRDO), India during the course of this study.

Author contributions

SC and JSK designed the study; JSK conducted the experiments; SC, SS, and JSK analyzed data; SC provided materials and supplies; JSK, SS, and SC wrote and approved this manuscript for final submission.

Compliance with ethical standards

Conflict of interest

Authors have no conflict of interest to declare.


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2017

Authors and Affiliations

  • Jyoti Swaroop Kumar
    • 1
  • Shubhankar Suman
    • 1
    • 2
  • Sudhir Chandna
    • 1
  1. 1.Division of Natural Radiation Response MechanismsInstitute of Nuclear Medicine and Allied SciencesDelhiIndia
  2. 2.Department of Biochemistry and Molecular & Cellular Biology, Lombardi Comprehensive Cancer CenterGeorgetown UniversityWashingtonUSA

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