Chemogenomic screening identifies the Hsp70 co-chaperone DNAJA1 as a hub for anticancer drug resistance

Heat shock protein 70 (HSP70) is an important molecular chaperone that regulates oncoprotein stability and tumorigenesis. However, attempts to develop anti-chaperone drugs targeting molecules such as HSP70 have been hampered by toxicity issues. HSP70 is regulated by a suite of co-chaperone molecules that bring "clients" to the primary chaperone for efficient folding. Rather than targeting HSP70 itself, here we have examined the feasibility of inhibiting the HSP70 co-chaperone DNAJA1 as a novel Anticancer strategy. We found DNAJA1 to be upregulated in a variety of cancers, suggesting a role in malignancy. To confirm this role, we screened the NIH Approved Oncology collection for chemical-genetic interactions with loss of DNAJA1 in Cancer. 41 compounds showed strong synergy with DNAJA1 loss, whereas 18 dramatically lost potency. Several hits were validated using a DNAJA1 inhibitor (116-9e) in castration-resistant prostate Cancer cell (CRPC) and spheroid models. Taken together, these results confirm that DNAJA1 is a hub for Anticancer drug resistance and that DNAJA1 inhibition is a potent strategy to sensitize Cancer cells to current and future therapeutics. The large change in drug efficacy linked to DNAJA1 suggests a personalized medicine approach where tumor DNAJA1 status may be used to optimize therapeutic strategy.