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Substituted toluenyl groups are considered as close isosteres of the thymine residue. They can be recognized by DNA polymerases as if they were thymine. These toluene derivatives are generally inert toward radical additions, including the [2+2] photo-cycloadditions, due to the stable structure of the aromatic ring and are usually used as solvents for radical reactions. Surprisingly, after incorporating toluene into the dinucleotide framework, we found that the UV excited thymine residue readily dimerizes with the toluenyl moiety through a [2+2] photo-addition reaction. Furthermore, the reaction site on the toluenyl moiety is not the C5C6 bond, as commonly observed in cyclobutane pyrimidine dimers, but the C4C5 or C3C4 instead. Such a reaction pattern suggests that in the stacked structure, it is one of these bonds, not the C5C6, that is close to the thymine C5C6 bond. A similar structural feature is found in DNA duplex with a thymine replaced by a 2,4-difluorotoluene. Our results argue that although the substituted toluenyl moieties closely mimic the size and shape of the thymine residue, their more hydrophobic nature determines that they stack on DNA bases differently from the natural thymine residue and likely cause local conformational changes in duplex DNA. [ABSTRACT FROM AUTHOR]

The synthesis of heterocyclic amides containing pyrrole, pyrrolidinone, and piperidone fragments is described and these are tested together with a wide range of previously prepared analogous derivatives for their binding activity at the urokinase receptor. [ABSTRACT FROM AUTHOR]

Pyrimidine dimers are the most common DNA lesions generated under UV radiation. To reveal the molecular mechanisms behind their formation, it is of significance to reveal the roles of each pyrimidine residue. We thus replaced the 5′-pyrimidine residue with a photochemically inert xylene moiety (X). The electron-rich X can be readily oxidized but not reduced, defining the direction of interbase electron transfer (ET). Irradiation of the XpT dinucleotide under 254 nm UV light generates two major photoproducts: a pyrimidine (6-4) pyrimidone analog (6-4PP) and an analog of the so-called spore photoproduct (SP). Both products are formed by reaction at C4=O of the photo-excited 3′-thymidine (T), which indicates that excitation of a single 'driver' residue is sufficient to trigger pyrimidine dimerization. Our quantum-chemical calculations demonstrated that photo-excited 3′-T accepts an electron from 5′-X. The resulting charge-separated radical pair lowers its energy upon formation of interbase covalent bonds, eventually yielding 6-4PP and SP. [ABSTRACT FROM AUTHOR]

N6‐methyladenosine (m6A) and long noncoding RNAs (lncRNAs) are both crucial regulators in non‐small‐cell lung cancer (NSCLC) tumorigenesis. However, the pathological roles of m6A and lncRNAs in NSCLC progression are still limited and undefined. Here, lncRNA ABHD11‐AS1 was upregulated in NSCLC tissue specimens and cells and the ectopic overexpression was closely correlated with unfavorable prognosis of NSCLC patients. Functionally, ABHD11‐AS1 promoted the proliferation and Warburg effect of NSCLC. Mechanistically, m6A profile was analyzed by methylated RNA immunoprecipitation sequencing (MeRIP‐Seq). MeRIP‐Seq presented that there was m6A modification site in ABHD11‐AS1. m6A methyltransferase‐like 3 (METTL3) installed the m6A modification and enhanced ABHD11‐AS1 transcript stability to increase its expression. In conclusion, our findings highlight the function and mechanism of METTL3‐induced ABHD11‐AS1 in NSCLC and inspire the understanding of m6A and lncRNA in cancer biology. [ABSTRACT FROM AUTHOR]