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Abstract: Thioredoxin reductase (TrxR) is critical for cellular redox regulation and is involved in tumor proliferation, apoptosis and metastasis. Its C-terminal redox-active center contains a cysteine (Cys497) and a unique selenocysteine (Sec498), which are exposed to solvent and easily accessible. Thus, it is becoming an important target for anticancer drugs. Selective inhibition of TrxR by 1,2-(bis-1,2-benzisoselenazol-3(2H)-one)ethane (4a) prevents proliferation of several cancer cell lines both in vivo and in vitro. Using the structure of 4a as a starting point, a series of novel bis-1,2-benzisoselenazol-3(2H)-ones was designed, prepared and tested to explore the structure–activity relationships (SARs) for this class of inhibitor and to improve their potency. Notably, 1,2-(5,5′-dimethoxybis(1,2-benzisoselenazol-3(2H)-one))ethane (12) was found to be more potent than 4a in both in vitro and in vivo evaluation. Its binding sites were confirmed by biotin-conjugated iodoacetamide assay and a SAR model was generated to guide further structural modification. [Copyright &y& Elsevier]

Background Glioma is the most common cause of cancer-related death. Therapy based on radiation seemed to effectively, while the radioresistance of several glioblastoma cells abolished the therapy. Thus, to employ the potential mechanism underlying the radioresistance is essential for glioma treatment. Methods Radioresistant cells were constructed using the X-ray radiation. Cell viability and apoptosis were detect using CCK-8 and Annexin-V/propidium iodide (PI), respectively. Real-time PCR and western blot were performed to determine gene expression. Luciferase reporter assay was carried out to detect the relationship between miR-183 and LRIG1. Mice xenotransplant model of glioma was established to detect the role of miR-183 in vivo. Results The expression of miR-183 was increased, while LRIG1 was decreased in resistant tissues rather than in sensitive tissues. The expression of LRIG1 was lower in radioresistant gliblastoma cell line U251R rather than in normal glioblastoma cell line U251. Overexpressed miR-183 suppressed cell apoptosis in radioresistance U251R cells (U251R). MiR-183 targets LRIG1 to regulate its expression. U251R cells transfected miR-183 inhibitor promoted the expression of LRIG1, and decreased the expression of EFGR and p-Akt, while U251R cells co-transfected with shRNA-LRIG1 abolished the effects of miR-183 knockdown. U251 cells transfected with miR-183 mimic decreased the expression of LRIG1, and promoted the expression of EFGR and p-Akt, while cells co-transfected with pcDNA-LRIG1 abolished the effects of miR-183 overexpression. In vivo experiments demonstrated that miR-183 inhibitor suppressed tumor growth, while miR-183 mimic promoted tumor growth. Conclusion MiR-183 overexpression promoted radioresistance of glioblastoma via down-regulating LRIG1 and increasing the activity of EFGR/Akt. [ABSTRACT FROM AUTHOR]