Cyclophilin A Inhibitor Debio-025 Targets Crk, Reduces Metastasis, and Induces Tumor Immunogenicity in Breast Cancer

Mol Cancer Res. 2020 Aug;18(8):1189-1201. doi: 10.1158/1541-7786.MCR-19-1144. Epub 2020 Apr 22.


The Crk adaptor protein, a critical modifier of multiple signaling pathways, is overexpressed in many cancers where it contributes to tumor progression and metastasis. Recently, we have shown that Crk interacts with the peptidyl prolyl cis-trans isomerase, Cyclophilin A (CypA; PP1A) via a G219P220Y221 (GPY) motif in the carboxyl-terminal linker region of Crk, thereby delaying pY221 phosphorylation and preventing downregulation of Crk signaling. Here, we investigate the physiologic significance of the CypA/Crk interaction and query whether CypA inhibition affects Crk signaling in vitro and in vivo. We show that CypA, when induced under conditions of hypoxia, regulates Crk pY221 phosphorylation and signaling in cancer cell lines. Using nuclear magnetic resonance spectroscopy, we show that CypA binds to the Crk GPY motif via the catalytic PPII domain of CypA, and small-molecule nonimmunosuppressive inhibitors of CypA (Debio-025) disrupt the CypA-CrkII interaction and restores phosphorylation of Crk Y221. In cultured cell lines, Debio-025 suppresses cell migration, and when administered in vivo in an orthotopic model of triple-negative breast cancer, Debio-025 showed antitumor efficacy either alone or in combination with anti-PD-1 mAb, reducing both tumor volume and metastatic lung dispersion. Furthermore, when analyzed by NanoString immune profiling, treatment of Debio-025 with anti-PD-1 mAb increased both T-cell signaling and innate immune signaling in tumor microenvironment. IMPLICATIONS: These data suggest that pharmacologic inhibition of CypA may provide a promising and unanticipated consequence in cancer biology, in part by targeting the CypA/CrkII axis that regulates cell migration, tumor metastasis, and host antitumor immune evasion.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents, Immunological / administration & dosage
  • Antineoplastic Agents, Immunological / pharmacology
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / metabolism
  • Cell Hypoxia
  • Cell Line, Tumor
  • Cell Movement / drug effects
  • Cyclosporine / administration & dosage*
  • Cyclosporine / pharmacology
  • Drug Synergism
  • Female
  • Gene Expression Profiling
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Immune Checkpoint Inhibitors / administration & dosage*
  • Immune Checkpoint Inhibitors / pharmacology
  • Mice
  • Models, Molecular
  • Neoplasm Metastasis
  • Peptidylprolyl Isomerase / chemistry
  • Peptidylprolyl Isomerase / metabolism*
  • Phosphorylation / drug effects
  • Protein Binding / drug effects
  • Protein Domains
  • Proto-Oncogene Proteins c-crk / chemistry
  • Proto-Oncogene Proteins c-crk / metabolism*
  • Sequence Analysis, RNA
  • Tumor Microenvironment / drug effects


  • Antineoplastic Agents, Immunological
  • CRK protein, human
  • Immune Checkpoint Inhibitors
  • Proto-Oncogene Proteins c-crk
  • Cyclosporine
  • PPIA protein, human
  • Peptidylprolyl Isomerase
  • alisporivir