OTU deubiquitinase 4 is silenced and radiosensitizes non-small cell lung cancer cells via inhibiting DNA repair

Abstract Background 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. Methods 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. Results 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. Conclusions This study uncovers a tumor-suppressing role of OTUD4 and that OTUD4 is a potential radiosensitizer for NSCLC

SPATA2 suppresses epithelial‐mesenchymal transition to inhibit metastasis and radiotherapy sensitivity in non–small cell lung cancer via impairing DVL1/β‐catenin signaling

Abstract Metastasis is the major cause of cancer‐related death of cancer patients. Epithelial‐mesenchymal transition (EMT) is one critical process during the cascade of tumor metastasis. EMT is a developmental program exploited by cancer cells to transition from epithelial state to mesenchymal state and confers metastatic properties as well as treatment resistance. Finding factors to inhibit EMT will greatly improve the prognosis patients. Spermatogenesis associated 2 (SPATA2) was originally isolated from human testis and proved playing a role in spermatogenesis. To date, however, the role of SPATA2 in oncogenesis is unknown. In the current study, by mining the public database and validating in a cohort of collected non–small cell lung cancer (NSCLC) specimens, we uncovered that the expression of SPATA2 positively correlated with the prognosis of patients and was an independent prognosis marker in NSCLC. Functional studies proved that ectopic overexpression of SPATA2 inhibited EMT resulting in impaired motility and invasiveness properties in vitro and metastasis in vivo, and increased radiosensitivity in NSCLC. Mechanistic investigation showed that SPATA2 could suppress the β‐catenin signaling via attenuating DVL1 ubiquitination to achieve the functions. Taken together, the current study revealed an inhibitory role of SPATA2 on EMT and that SPATA2 could be a potential target for therapy of NSCLC

Molecular modeling of human APOBEC3G to predict the binding modes of the inhibitor compounds IMB26 and IMB35

APOBEC3G(A3G) is a host cytidine deaminase that incorporates into HIV-1 virions and efficiently inhibits viral replication. The virally encoded protein Vif binds to A3G and induces its degradation, thereby counteracting the antiviral activity of A3G. Vif-mediated A3G degradation clearly represents a potential target for anti-HIV drug development. Currently, there is an urgent need for understanding the three dimensional structure of full-length A3G. In this work, we use a homology modeling approach to propose a structure for A3G based on the crystal structure of APOBEC2 (APO2) and the catalytic domain structure of A3G. Two compounds, IMB26 and IMB35, which have been shown to bind to A3G and block degradation by Vif, were docked into the A3G model and the binding modes were generated for further analysis. The results may be used to design or optimize molecules targeting Vif–A3G interaction, and lead to the development of novel anti-HIV drugs

Microbial Natural Product Alternariol 5-O-Methyl Ether Inhibits HIV-1 Integration by Blocking Nuclear Import of the Pre-Integration Complex

While Highly Active Antiretroviral Therapy (HAART) has significantly decreased the mortality of human immunodeficiency virus (HIV)-infected patients, emerging drug resistance to approved HIV-1 integrase inhibitors highlights the need to develop new antivirals with novel mechanisms of action. In this study, we screened a library of microbial natural compounds from endophytic fungus Colletotrichum sp. and identified alternariol 5-O-methyl ether (AME) as a compound that inhibits HIV-1 pre-integration steps. Time-of addition analysis, quantitative real-time PCR, confocal microscopy, and WT viral replication assay were used to elucidate the mechanism. As opposed to the approved integrase inhibitor Raltegravir, AME reduced both the integrated viral DNA and the 2-long terminal repeat (2-LTR) circular DNA, which suggests that AME impairs the nuclear import of viral DNA. Further confocal microscopy studies showed that AME specifically blocks the nuclear import of HIV-1 integrase and pre-integration complex without any adverse effects on the importin α/β and importin β-mediated nuclear import pathway in general. Importantly, AME inhibited Raltegravir-resistant HIV-1 strains and exhibited a broad anti-HIV-1 activity in diverse cell lines. These data collectively demonstrate the potential of AME for further development into a new HIV inhibitor, and suggest the utility of viral DNA nuclear import as a target for anti-HIV drug discovery

MOESM1 of 2-thio-6-azauridine inhibits Vpu mediated BST-2 degradation

Additional file 1: Figure S1. 2-thio-6-azauridine inhibits Vpu-mediated down-regulation of cell surface BST-2 (FACS). HeLa-Vpu and HeLa cells were treated with increasing concentrations of 2-thio-6-azauridine (0.05 µM、0.5 µM、5 µM) for 24 h. Cell surface BST-2 was measured using flow cytometry

MOESM3 of 2-thio-6-azauridine inhibits Vpu mediated BST-2 degradation

Additional file 3: Figure S3. FACS result of Figure 6. A) 2-thio-6-azauridine dose not affect Vpu induced down-regulation of cell surface CD4. (B) 2-thio-6-azauridine has no inhibitory effect upon K5 induced BST-2 degradation