The binding affinity of human pediatric respiratory syncytial virus Phosphoprotein's C-terminal tail to nucleocapsid can be improved by a rationally designed halogen-bonded system.

Human respiratory syncytial virus (hRSV) is a common contagious virus that causes infections of pediatric pneumonia and specifically impacts infants and small children. The hRSV phosphoprotein is a key component of the viral RNA polymerase, which can interact with nucleocapsid and other partners through its C-terminal tail (CTT) to promote the formation of viral transcriptase complex, where the Phe241 is a key anchor residue. Based on the crystal template-modeled complex structure of hRSV nucleocapsid with a peptidic segment derived from the phosphoprotein's CTT, we successfully introduced a rationally designed halogen-bonded system to the complex interface by substituting para (p)-position of the side-chain phenyl moiety of CTT Phe241 residue with a halogen atom X (X = F, Cl, Br or I). The halogen-bonded system consists of a halogen bond (X-bond) between nucleocapsid Ser131 residue and CTT Phe241 residue as well as a hydrogen bond (H-bond) between nucleocapsid Ser131 residue and nucleocapsid Glu128 residue; the X-bond and H-bond share a common hydroxyl group of nucleocapsid Ser131 residue. High-level theoretical calculations suggested that bromine Br is the best choice that can render strong potency for the X-bond and can confer high affinity to the nucleocapsid-CTT binding. Affinity analysis revealed that the p-brominated CTT ([p]bCTT) exhibited 6.3-fold affinity improvement relative to its nonhalogenated counterpart. In contrast, the Br-substitutions at ortho (o)- and meta (m)-positions, which resulted in two negative controls of o-brominated [o]bCTT and m-brominated [m]bCTT, respectively, were unable to form effective X-bond with nucleocapsid according to theoretical investigation and did not improve the binding affinity essentially relative to native CTT.

TUSC8 enhances cisplatin sensitivity of NSCLC cells through regulating VEGFA.

PURPOSE: We aimed at studying LncRNA TUSC8 expression in non-small cell lung cancer (NSCLC) cells and its sensitivity to cisplatin chemotherapy, and explore its role in the occurrence, development and treatment of NSCLC. METHODS: NSCLC tissues and adjacent normal ones were randomly selected from 45 patients in our hospital who were pathologically diagnosed as NSCLC. Then H358 and H1299 cells were treated with cisplatin at different concentrations (0 µM, 2 µM, 4 µM, 8 µM, 16 µM) for 24 hours. RESULTS: Our data showed that long non-coding RNA (LncRNA) TUSC8 mRNA expression in NSCLC tissue specimens was remarkably lower than that in adjacent ones. A great link was found between LncRNA TUSC8 and tumor size, TNM stage and overall survival rates of patients with Lung cancer (LCa). The proliferation of NSCLC cells remarkably reduced after overexpression of LncRNA TUSC8 compared with the control group pcDNA3.1-NC, while cell apoptosis indicated an opposite trend. A binding relationship between LncRNA TUSC8 and its downstream target gene VEGFA was verified by luciferase assay. The proliferation rate of NSCLC cells decreased with the increase of cisplatin concentration, and the inhibition rate of LncRNA TUSC8 overexpression group was higher than that of the control group pcDNA3.1-NC under different concentrations of cisplatin. CONCLUSIONS: Lowly expressed LncRNA TUSC8 in NSCLC is related to pathological parameters and prognosis of NSCLC patients. It may negatively regulate VEGFA by targeting its 3'UTR, thereby increasing the sensitivity of NSCLC cell lines to cisplatin, inhibiting the proliferation of NSCLC cells and promoting their apoptosis.