Abstract 2057 The role of dnaja2 in reactive oxygen species homeostasis

To conduct a more in-depth examination of the involvement of DNAJA2 in the cellular reaction to the toxic effects of doxorubicin during cancer treatment. DnaJ homolog subfamily A member 2, DNAJA2, is a constituent of the heat-shock protein 40 family. It serves as a co-chaperone for Hsc70, aiding in the hydrolysis of ATP and assisting the refolding process of denatured proteins. DNAJA2 protein has been reported to exhibit elevated levels of expression in diverse cancers in humans. DNAJA2 gene amplification or overexpression is a common genetic alteration occurring in breast cancers. Our previous results indicate that DNAJA2 can rescue the sensitivity of a ydj1 yeast deletion mutant to doxorubicin. The rescue was specific to the reactive oxygen species (ROS) activity of doxorubicin and not to the generation of DNA double-strand breaks. To further investigate the role of DNAJA2 in the response to cytotoxic stress of doxorubicin in cancer therapy, we proceeded to downregulate DNAJA2 in the MDA-MB-231 breast cancer cell line, which is representative of triple-negative breast cancer (TNBC). DNAJA2 was knocked down in the MDA-MB-231 cell line using a lentivirus-mediated short hairpin RNA (shRNA) and cells were made stably transfected by selection with puromycin. The knocked down (DNAJA2-KD) cells display a significant reduction in the levels of DNAJA2 protein. DNAJA2-KD cells show sensitivity to heat-shock and anthracyclines, reduced migration and interestingly, increased levels of ROS. Further analysis shows that DNAJA2-KD cells present a decline in the expression of catalase and SOD2, but not SOD 1 in comparison to the MDA-MB-231 wild type cells. These results indicate that the decrease in DNAJA2 expression significantly impacts ROS homeostasis in MDA-MB-231 cells, suggesting that redox proteins may constitute client proteins of DNAJA2. Funding provided by the Florida-California Cancer Research, Education and Engagement (CaRE2) Health Equity Center. Tissue Modeling and Drug Discovery Core. 2U54CA233396-06, subproject 5684.