hMOF reduction enhances radiosensitivity through the homologous recombination pathway in non-small-cell lung cancer

PURPOSE: Human males absent on the first (hMOF) is a histone acetyltransferase (HAT) and is responsible for acetylating histone H4 at lysine 16 (H4K16). Recent studies have indicated that hMOF is overexpressed in non-small-cell lung cancer (NSCLC) as an oncogene. The aim of this study is to profile the prognostic roles of hMOF in patients with unresectable stage III NSCLC undergoing definitive radiotherapy (RT) and in the radiosensitivity of human NSCLC cells. MATERIALS AND METHODS: The expression of hMOF was detected in 24 normal and tumor-paired fresh-frozen NSCLC tissue samples. The immunohistochemistry was conducted, and the correlation of hMOF with clinicopathological parameters was studied in tissues from 90 patients with unresectable stage III NSCLC who underwent definitive RT. Radiation sensitivity was monitored using clonogenic assays in NCI-H1299 and A549 NSCLC cell lines with hMOF knockdown. RESULTS: hMOF was overexpressed in NSCLC tissues compared with non-cancerous tissues. Compared to patients with downregulated hMOF, upregulated hMOF was observed in 51.1% (46/90) of the patients, who showed a significantly worse 5-year survival rate (5.4% vs 22.9%, P=0.025). hMOF expression was an independent prognostic factor of unresectable stage III NSCLC patients who underwent definitive RT. Silencing hMOF increased in vitro the sensitive enhancing ratio (SER) of NSCLC cell lines and downregulated the expression of phospho-ataxia telangiectasia mutated (p-ATM) and RAD51 after irradiation (IR). CONCLUSION: Overexpression of hMOF predicts poor prognosis in patients with unresectable stage III NSCLC undergoing definitive RT. Downregulating hMOF might be a promising intervention to improve the outcome after RT.