PT  - JOURNAL ARTICLE
AU  - Mary E. Law
AU  - Elham Yaaghubi
AU  - Amanda F. Ghilardi
AU  - Bradley J. Davis
AU  - Renan B. Ferreira
AU  - Jin Koh
AU  - Sixue Chen
AU  - Sadie F. DePeter
AU  - Christopher M. Schilson
AU  - Chi-Wu Chiang
AU  - Coy D. Heldermon
AU  - Peter Nørgaard
AU  - Ronald K. Castellano
AU  - Brian K. Law
TI  - Identification of the Molecular Targets of Disulfide Bond Disrupting Agents
AID  - 10.1101/2021.01.13.426390
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.01.13.426390
4099  - http://biorxiv.org/content/early/2021/01/15/2021.01.13.426390.short
4100  - http://biorxiv.org/content/early/2021/01/15/2021.01.13.426390.full
AB  - Breast cancer mortality remains unacceptably high, indicating a need for safer and more effective therapeutic agents. Disulfide bond Disrupting Agents (DDAs) were previously identified as a novel class of anticancer compounds that selectively kill cancers that overexpress the Epidermal Growth Factor Receptor (EGFR) or its family member HER2. DDAs kill EGFR+ and HER2+ cancer cells via the parallel downregulation of EGFR, HER2, and HER3 and activation/oligomerization of Death Receptors 4 and 5 (DR4/5). However, the mechanisms by which DDAs mediate these effects are unknown. Affinity purification analyses employing biotinylated-DDAs reveal that the Protein Disulfide Isomerase (PDI) family members AGR2, AGR3, PDIA1, and ERp44 are DDA target proteins. Further analyses demonstrate that shRNA-mediated knockdown of AGR2 and ERp44, or expression of ERp44 mutants, enhance basal and DDA-induced DR5 oligomerization. DDA treatment of breast cancer cells disrupts PDIA1 and ERp44 mixed disulfide bonds with their client proteins. Together, these results reveal DDAs as the first small molecule, active site inhibitors of AGR2 and ERp44, demonstrate a role for AGR2 and ERp44 in regulating the activity, stability, and localization of DR4 and DR5, and nominate ERp44 as a new molecular target for anticancer therapeutics.Competing Interest StatementBrian Law and Ronald Castellano are inventors on issued and pending patents related to the DDA compounds and are founding members of Quattro Therapeutics, LLC.