G-quadruplex-guided RNA engineering to modulate CRISPR-based genomic regulation.

It is important to develop small moelcule-based methods to modulate gene editing and expression in human cells. The roles of the G-quadruplex (G4) in biological systems have been widely studied. Here, G4-guided RNA engineering is performed to generate guide RNA with G4-forming units (G4-gRNA). We further demonstrate that chemical targeting of G4-gRNAs holds promise as a general approach for modulating gene editing and expression in human cells. The rich structural diversity of RNAs offers a reservoir of targets for small molecules to bind, thus creating the potential to modulate RNA biology.

Bioactivatable reductive cleavage of azobenzene for controlling functional dumbbell oligodeoxynucleotides.

Application of stimuli-responsive bioactive molecules is an attractive strategy due to use for target special tissues and cells. Here, we reported synthesis of an azo-linker, 2,2'-dimethoxyl-4,4'-dihydroxymethylazobenzene (mAzo), which was more effectively recognized and cleaved by reducing glutathione (GSH) via comparing with 4,4'-dihydroxymethylazobenzene (Azo). In addition, mAzo is further exploited to engineer dumbbell asODNs, which could result in the release of asODNs and thus modulate their hybridization to target nucleic acids. The present study is the first example to disclose efficient reductive cleavage of azobenzene by GSH to generate aromatic amine. This would provide a valuable strategy for tunable cell-specific release of ODNs and modulation of known disease-causing gene expression in cancer cells.

Design, synthesis and antitumor activity of Novel Sorafenib derivatives bearing pyrazole scaffold.

Four series of Sorafenib derivatives bearing pyrazole scaffold (8a-m, 9a-c, 10a-e and 11a) were synthesized and characterized by NMR and MS. All of the target compounds were evaluated for the cytotoxicity against A549, HepG2, MCF-7, and PC-3 cancer cell lines and some selected compounds were further evaluated for the activity against VEGFR-2/KDR, BRAF, CRAF, c-Met, EGFR and Flt-3 kinases. Compounds 8b and 8i were more active than that of compounds 8h, 9a, especially the IC50 value of compounds 8b on VEGFR-2 kinase was 0.56µM. And compound 8b exhibited moderate to good activity toward c-Met and showed moderate to no activity against CRAF, c-Met, EGFR, Flt-3 kinases. Eleven of the target compounds exhibited moderate to good antitumor activities. The most promising compound 8b showed strong antitumor activities against A549, HepG2 and MCF-7 cell lines with IC50 values of 2.84±0.78µM, 1.85±0.03µM and 1.96±0.28µM, which were equivalent to Sorafenib (2.92±0.68µM, 3.44±0.50µM and 3.18±0.18µM). Structure-activity relationships (SARs) and docking studies indicated that the pyrazole scaffolds exerted key effect on antitumor activities of target compounds. Substitutions of aryl group at C-3 positions had a significant impact on the antitumor activities, and 3-Br substitution produced the best potency.

Chemical Control of CRISPR Gene Editing via Conditional Diacylation Crosslinking of Guide RNAs.

Conditional control of RNA structure and function has emerged as an effective toolkit. Here, a strategy based on a one-step introduction of diacylation linkers and azide groups on the 2'-OH of RNA is advance. Selected from eight phosphine reagents, it is found that 2-(diphenylphosphino)ethylamine has excellent performance in reducing azides via a Staudinger reduction to obtain the original RNA. It is demonstrated that the enzymatic activities of Cas13 and Cas9 can be regulated by chemically modified guide RNAs, and further achieved ligand-induced gene editing in living cells by a controllable CRISPR/Cas9 system.