Therapeutic benefits of niraparib tosylate as radio sensitizer in esophageal squamous cell carcinoma: an in vivo and in vitro preclinical study

Esophageal squamous cell carcinoma is associated with high morbidity and mortality rate for which radiotherapy is the main treatment modality. Niraparib, a Poly (ADP-ribose) polymerase 1 inhibitors (PARPi) was previously reported to confer radiosensitivity in different malignancies including non-small cell lung cancer. In this study, we assessed the in vivo ability of niraparib in conferring radiosensitivity to esophageal squamous cell carcinoma cells.In this study, KYSE-30 and KYSE-150 cell lines were selected as in vivo esophageal squamous cell carcinoma models. The experimental groups were: niraparib tosylate alone, radiotherapy alone, control (no intervention), and combination therapy (radiotherapy + niraparib tosylate). Cell cytotoxicity assay, colony formation assay, flow cytometry, immunofluorescence, Western blotting, immunohistochemistry, lentivirus transfection analysis, and xenograft models were used for confirming radiosensitizing ability of niraparib and to investigate the possible cellular mechanism involved in radiosensitization.The colony formation efficiency of the combination group was significantly much lower than that of the single radiation group (P < 0.01). Cell cytotoxicity assay demonstrated a significant reduction in proliferation of irradiated cells after treatment with niraparib tosylate compared to niraparib tosylate alone (P < 0.01). Cell apoptosis significantly increased in the combination group compared to either niraparib tosylate or radiotherapy alone (P < 0.01). Rate of tumor suppression rate was significantly high in the combined treatment group (P < 0.01) but, significantly decreased in nude mice. Western blot and lentivirus infection model suggested overexpression of FANCG genes to confer radiosensitivity.These results suggest that the synergistic effect of niraparib tosylate and radiation may be related to the down-regulation of FANCG.