Inhibiting Importin 4-mediated nuclear import of CEBPD enhances chemosensitivity by repression of PRKDC-driven DNA damage repair in cervical cancer

Oncogene. 2020 Aug;39(34):5633-5648. doi: 10.1038/s41388-020-1384-3. Epub 2020 Jul 13.

Abstract

Cervical cancer (CC) remains highest in the mortality of female reproductive system cancers, while cisplatin (CDDP) resistance is the one of main reasons for the lethality. Preceding evidence has supported that karyopherins are associated with chemoresistance. In this study, we simultaneously compared CDDP-incomplete responders with CDDP-complete responders of CC patients and CDDP-insensitive CC cell lines with CDDP-sensitive group. We finally identified that DNA-PKcs (PRKDC) was related to CDDP sensitivity after overlapping in CC sample tissues and CC cell lines. Further functional assay revealed that targeting PRKDC by shRNA and NU7026 (specific PRKDC inhibitor) could enhance CDDP sensitivity in vitro and in vivo, which was mediated by impairing DNA damage repair pathway in CC. Mechanistically, we found that PRKDC was transcriptionally upregulated by CCAAT/enhancer-binding protein delta (CEBPD), while intriguingly, CDDP treatment strengthened the transcriptional activity of CEBPD to PRKDC. We further disclosed that Importin 4 (IPO4) augmented the nuclear translocation of CEBPD through nuclear localization signals (NLS) to activate PRKDC-mediated DNA damage repair in response to CDDP. Moreover, we demonstrated that IPO4 and CEBPD knockdown improved CDDP-induced cytotoxicity in vitro and in vivo. Together, we shed the novel insight into the role of IPO4 in chemosensitivity and provide a clinical translational potential to enhance CC chemosensitivity since the IPO4-CEBPD-PRKDC axis is actionable via NU7026 (PRKDC inhibitor) or targeting IPO4 in combination with CDDP.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus / genetics
  • Animals
  • Antineoplastic Agents / pharmacology
  • CCAAT-Enhancer-Binding Protein-delta / genetics*
  • CCAAT-Enhancer-Binding Protein-delta / metabolism
  • Cell Line, Tumor
  • Chromones / pharmacology
  • Cisplatin / pharmacology*
  • DNA Damage
  • DNA Repair / drug effects*
  • DNA Repair / genetics
  • DNA-Activated Protein Kinase / antagonists & inhibitors
  • DNA-Activated Protein Kinase / genetics*
  • DNA-Activated Protein Kinase / metabolism
  • Drug Resistance, Neoplasm / genetics
  • Female
  • Gene Expression Regulation, Neoplastic
  • HeLa Cells
  • Humans
  • Membrane Transport Proteins / genetics*
  • Membrane Transport Proteins / metabolism
  • Mice, Nude
  • Morpholines / pharmacology
  • RNA Interference
  • Uterine Cervical Neoplasms / genetics*
  • Uterine Cervical Neoplasms / metabolism
  • Uterine Cervical Neoplasms / therapy
  • Xenograft Model Antitumor Assays / methods

Substances

  • 2-(morpholin-4-yl)benzo(h)chromen-4-one
  • Antineoplastic Agents
  • CEBPD protein, human
  • Chromones
  • IPO4 protein, human
  • Membrane Transport Proteins
  • Morpholines
  • CCAAT-Enhancer-Binding Protein-delta
  • DNA-Activated Protein Kinase
  • PRKDC protein, human
  • Cisplatin