Olaparib enhancing radiosensitization and anti-metastatic effect of oral cancer by targeting IL-17A signal.

Purpose: We tested whether the PARP inhibitor, Olaparib, can effectively enhance radiosensitivity while inhibiting OSCC growth and metastasis in vitro and in vivo. Patient samples were used for survival validation.

Methods: The present study investigated the effect of Olaparib and ionizing radiation (IR) on clonogenic, migratory, and invasive ability in human IR-sensitive (OML1) and IR-resistant (OML1-R) OSCC cell lines. We next explored the underlying mechanism with ELISA and a Western blotting assay. Two in vivo mouse models were established to investigate the efficacy of Olaparib combined with radiotherapy (RT) on local tumor growth and lung metastasis. IL-17 A expression was confirmed in tissue specimens of OSCC patients by immunohistochemistry.

Results: We found that Olaparib, in combination with IR, substantially inhibited cell growth, migration, and invasion in vitro. Mechanistically, the Olaparib treatment significantly reduced the secretion of IL-17 A in irradiated OSCC cells by attenuating NF-κB and p38 activity. Consistently, Olaparib enhanced the radiosensitivity and, with RT, synergistically reduced both tumor growth and lung metastasis in mice. In addition, OSCC patients with high IL-17 A expression were substantially associated with an increased risk of lymph node involvement and worse survival.

Conclusions: This study has highlighted that Olaparib displays radiosensitizing and antimetastatic effects by inhibiting the IL-17 A-dependent signal. Remarkably, Olaparib could provide a remarkable anticancer efficacy to improve treatment response in OSCC patients with recurrent/metastatic disease after RT.