Radiotherapy is becoming one major therapeutics for non-small cell lung cancer (NSCLC). Identifying novel radiosensitizers will greatly increase the efficacy of radiotherapy and benefit more patients. OTU deubiquitinase 4 (OTUD4) has been reported involved in DNA damage repair pathways and could be a potential target for chemotherapy therapy. This study aimed to investigate the roles of OTUD4 in regulation of radiosensitivity of NSCLC via modulating DNA repair. The expression of OTUD4, γ-H2Ax and ATM/CHK2/p53 pathway-related signaling molecules were detected by Western blotting and QRT-PCR. The methylation of OTUD4 promoter was investigated by 5-aza-deoxycytidine treatment, methylation-specific PCR and bisulfite genomic sequencing assays. Radiosensitivity was assessed by the clonogenic formation assay. Cell cycle, cell apoptosis were analyzed by flow cytometry. DNA damage and repair were determined by comet assay, γ-H2Ax foci staining and flow cytometry. OTUD4 is dramatically downregulated in NSCLC and its downregulation significantly correlates with poor prognosis of NSCLC patients. Promoter hypermethylation is responsible for the loss of OTUD4 expression in NSCLC cells. Overexpression of OTUD4 increases radiosensitivity of NSCLC cells exhibiting as impaired clonogenic formation ability, enhanced cell cycle arrest and increased cell apoptosis. Moreover, molecular mechanism study reveals that OTUD4 radiosensitizs NSCLC cells via ATM/CHK2/P53 signaling and inhibiting homology-directed repair of DNA double strand breaks induced by ionizing radiation. This study uncovers a tumor-suppressing role of OTUD4 and that OTUD4 is a potential radiosensitizer for NSCLC.

To determine the therapeutic efficacy and safety of risk‐adapted stereotactic body radiation therapy (SBRT) schedules for patients with early‐stage central and ultra‐central inoperable non‐small cell lung cancer. From 2006 to 2015, 80 inoperable T1‐2N0M0 NSCLC patients were treated with two median dose levels: 60 Gy in six fractions (range, 48‐60 Gy in 4‐8 fractions) prescribed to the 74% isodose line (range, 58%‐79%) for central lesions (ie within 2 cm of, but not abutting, the proximal bronchial tree; n = 43), and 56 Gy in seven fractions (range, 48‐60 Gy in 5‐10 fractions) prescribed to the 74% isodose line (range, 60%‐80%) for ultra‐central lesions (ie abutting the proximal bronchial tree; n = 37) on consecutive days. Primary endpoint was overall survival (OS); secondary endpoints included progression‐free survival (PFS), tumor local control rate (LC), and toxicity. Median OS and PFS were 64.47 and 32.10 months (respectively) for ultra‐central patients, and not reached for central patients. Median time to local failure, regional failure, and any distant failures for central versus ultra‐central lesions were: 27.37 versus 26.07 months, 20.90 versus 12.53 months, and 20.85 versus 15.53 months, respectively, all P < .05. Multivariate analyses showed that tumor categorization (ultra‐central) and planning target volume ≥52.76 mL were poor prognostic factors of OS, PFS, and LC, respectively (all P < .05). There was one grade 5 toxicity; all other toxicities were grade 1‐2. Our results showed that ultra‐central tumors have a poor OS, PFS, and LC compared with central patients because of the use of risk‐adapted SBRT schedules that allow for equal and favorable toxicity profiles.

Prostate tumor over expressed gene 1 (PTOV1) has been reported as an oncogene in several human cancers. However, the clinical significance and biological role of PTOV1 remain elusive in non-small cell lung cancer (NSCLC). The Cancer Genome Atlas (TCGA) data and NCBI/GEO data mining, western blotting analysis and immunohistochemistry were employed to characterize the expression of PTOV1 in NSCLC cell lines and tissues. The clinical significance of PTOV1 in NSCLC was studied by immunohistochemistry statistical analysis and Kaplan–Meier Plotter database mining. A series of in-vivo and in-vitro assays, including colony formation, CCK-8 assays, flow cytometry, wound healing, trans-well assay, tumor sphere formation, quantitative PCR, gene set enrichment analysis (GSEA), immunostaining and xenografts tumor model, were performed to demonstrate the effects of PTOV1 on chemosensitivity of NSCLC cells and the underlying mechanisms. PTOV1 is overexpressed in NSCLC cell lines and tissues. High PTOV1 level indicates a short survival time and poor response to chemotherapy of NSCLC patients. Depleting PTOV1 increased sensitivity to chemotherapy drugs cisplatin and docetaxel by increasing cell apoptosis, inhibiting cell migration and invasion. Our study verified that depleting PTOV1 attenuated cancer stem cell traits through impairing DKK1/β-catenin signaling to enhance chemosensitivity of NSCLC cells. These results suggest that PTOV1 plays an important role in the development and progression of human NSCLC and PTOV1 may serve as a therapeutic target for NSCLC patients.