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Niraparib-induced STAT3 inhibition increases its antitumor effects

Qianqian Zhao1,2, Adrian Kohut3, Yi-Jia Li1

  • 1Department of Immuno-Oncology, Beckman Research Institute, City of Hope National Medical Center, Duarte, CA, United States.

Frontiers in Oncology
|November 3, 2022
PubMed

Insights

Niraparib effectively inhibits ovarian and pancreatic cancer cell growth, unlike Olaparib. This poly(ADP-ribosyl)ation polymerase inhibitor (PARPi) works by inhibiting STAT3 activity, offering potential treatment for cancers regardless of BRCA mutation status.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cancer Therapeutics

Background:

  • Poly(ADP-ribosyl)ation polymerase inhibitors (PARPis) are promising cancer therapies, particularly for BRCA-mutated cancers.
  • Olaparib (PARPi) is approved for specific deficiencies, while Niraparib is approved for ovarian cancer regardless of DNA repair status.
  • The mechanism of Niraparib's efficacy in non-deficient cancers and its potential in pancreatic ductal adenocarcinoma (PDAC) remain unclear.

Purpose of the Study:

  • To investigate the efficacy of Niraparib compared to Olaparib in ovarian and PDAC tumor cells.
  • To elucidate the molecular mechanism underlying Niraparib's anti-tumor activity, focusing on STAT3 signaling.
  • To explore Niraparib's potential as a therapeutic agent for PDAC patients irrespective of BRCA mutation status.

Main Methods:

  • In vitro cell growth inhibition assays comparing Niraparib and Olaparib.
  • Analysis of STAT3 activity and downstream gene expression in cancer cell lines and patient tumors.
  • Investigation of the role of SRC tyrosine kinase in Niraparib's mechanism of action.
  • Assessment of Niraparib's efficacy in models with and without BRCA mutations.

Main Results:

  • Niraparib demonstrated superior inhibition of ovarian and PDAC tumor cell growth compared to Olaparib, irrespective of BRCA mutational status.
  • Niraparib, unlike Olaparib, inhibited STAT3 activity and regulated apoptosis-associated STAT3 downstream genes.
  • Niraparib's mechanism involves the inhibition of phosphorylated STAT3 (pSTAT3) through interference with SRC tyrosine kinase.
  • Overexpression of a constitutively active STAT3 mutant rescued Niraparib-induced apoptosis, confirming STAT3's role.

Conclusions:

  • Niraparib exhibits potent anti-tumor activity in ovarian and PDAC cells, independent of BRCA mutation status.
  • Niraparib's efficacy is mediated through the inhibition of STAT3 signaling via SRC tyrosine kinase.
  • These findings support the potential of Niraparib as a therapeutic option for a broader range of PDAC patients, including those without BRCA mutations.
Keywords:
SRCSTAT3niraparibovarian cancerpancreatic cancer

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