Abstract 1490: Role of sub-cellular specific reactive oxygen species in heart regeneration after cancer therapy
Authors: Abdisalaam Salim , Bhattacharya Souparno , Srinivasan Kalayarasan , Mukherjee Shibani , Sadek Hesham A. , Asaithamby Aroumougame 
Published: July 2017

Abstract
Introduction: Cardiovascular disease and cancer are the two leading causes of morbidity and mortality worldwide. As advancements in radiation therapy (RT) have significantly increased the number of cancer survivors, the risk of radiation-induced cardiovascular disease in this group is a growing concern. However, the molecular mechanism of radiation-induced heart failure is still elusive. Recently, it has been discovered that the reactive oxygen species (ROS)-mediated oxidative DNA damage is the primary upstream mechanism that prevents cardiomyocyte proliferation. Therefore, elucidating the spatial and temporal aspects of ROS production will lead to the development of countermeasures to prevent heart injury following chest radiotherapy.
Methods: We have generated GSH redox potential (Grx-roGFP) ROS probe targeted to cytoplasm, chromatin, nucleolus, telomere, nuclear inner membrane and heterochromatin. These probes have been inserted into cardiomyocytes specific AAV9 vectors which were used to infect cardiomyocytes both in vitro an in vivo. For in vivo study, we infected three months old mice with high-titer AAV particles via tail vein injection and then exposed to chest-only radiation (5-10 Gy). At different post-radiation times, fresh heart slices of 300-500 µM thickness were either mock- or treated with mitochondrial electron transport complex (ETC) inhibitors and then subjected to live tissue imaging using a confocal microscope.
Results: Interestingly, our results showed that the distribution of basal ROS levels is not uniform in different sub-nuclear compartments. Significantly, upon the induction of oxidative stress, the ROS levels was elevated in all the cellular compartments, but the extent of ROS level was significantly higher in the cytoplasm. Similarly, radiation altered ROS levels in all the cellular compartments; however the effect of radiation on the ROS levels was sub-nuclear compartment-specific. Intriguingly, we found that the complex IV of the ETC was critical for the maintenance of ROS levels in different cellular compartments as compared with complexes I and II.
Conclusion and Future Directions: Our data clearly indicate that the spatial and temporal levels of ROS are not uniform across the cell and the mitochondrial ETC plays a major role in regulation ROS levels in different sub-nuclear compartments. The results obtained from this study can be utilized to develop sub-cellular compartment specific targeted both genetic and pharmacological ROS scavengers that will help to regenerate adult heart by re-activating the proliferative capacity of cardiomyocytes following cancer therapy. Finally, our novel approach can be applied to assess alterations in ROS levels in different cancers.
Funding: This work was supported by the NASA (NNX13AD57G/NNX15AE06G) CPRIT (RP160520) and NIH R01AG053341 grants.
Citation Format: Salim Abdisalaam, Souparno Bhattacharya, Kalayarasan Srinivasan, Shibani Mukherjee, Hesham A. Sadek, Aroumougame Asaithamby. Role of sub-cellular specific reactive oxygen species in heart regeneration after cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1490. doi:10.1158/1538-7445.AM2017-1490