Anti-tumor efficacy of a novel CLK inhibitor via targeting RNA splicing and MYC-dependent vulnerability.

The modulation of pre-mRNA splicing is proposed as an attractive anti-neoplastic strategy, especially for the cancers that exhibit aberrant pre-mRNA splicing. Here, we discovered that T-025 functions as an orally available and potent inhibitor of Cdc2-like kinases (CLKs), evolutionally conserved kinases that facilitate exon recognition in the splicing machinery. Treatment with T-025 reduced CLK-dependent phosphorylation, resulting in the induction of skipped exons, cell death, and growth suppression in vitro and in vivo Further, through growth inhibitory characterization, we identified high CLK2 expression or MYC amplification as a sensitive-associated biomarker of T-025. Mechanistically, the level of CLK2 expression correlated with the magnitude of global skipped exons in response to T-025 treatment. MYC activation, which altered pre-mRNA splicing without the transcriptional regulation of CLKs, rendered cancer cells vulnerable to CLK inhibitors with synergistic cell death. Finally, we demonstrated in vivo anti-tumor efficacy of T-025 in an allograft model of spontaneous, MYC-driven breast cancer, at well-tolerated dosage. Collectively, our results suggest that the novel CLK inhibitor could have therapeutic benefits, especially for MYC-driven cancer patients.

Total synthesis of buergerinin F via effective construction of the asymmetric quaternary carbons using an enantioselective aldol reaction.

An efficient method for the synthesis of (+)-buergerinin F is established via the enantioselective aldol reaction of a tetra-substituted ketene silyl acetal with crotonaldehyde, followed by intramolecular Wacker-type ketalization.

4-(Dimethylamino)pyridine N-oxide (DMAPO): an effective nucleophilic catalyst in the peptide coupling reaction with 2-methyl-6-nitrobenzoic anhydride.

Various carboxamides or peptides were synthesized from the corresponding carboxylic acids and amines or alpha-amino acids in high yields by the catalysis of 4-(dimethylamino)pyridine N-oxide (DMAPO) with 2-methyl-6-nitrobenzoic anhydride (MNBA). Because the segment-coupling reaction of alpha-amino acids proceeds through the effective activation of the carboxylic acid moieties with DMAPO in the presence of tertiary amines under mild conditions, undesired racemization was hardly observed in the synthesis of oligopeptides such as Z-Gly-Phe-Val-OMe, Z-Phe-Val-Ala-OMe, and Bz-Val-Val-OMe.

Taxol derivatives are selective inhibitors of DNA polymerase alpha.

During screening for mammalian DNA polymerase inhibitors, we found and succeeded in isolating a potent inhibitor from a higher plant, Taxus cuspidate. The compound was unexpectedly determined to be taxinine, an intermediate of paclitaxel (taxol) metabolism. Taxinine was found to selectively inhibit DNA polymerase alpha (pol.alpha) and beta (pol.beta). We therefore, tested taxol and other derivatives and found that taxol itself had no such inhibitory effect, and only taxinine could inhibit both pol.alpha and beta. The other compounds used, one derivative, cephalomannine, and five intermediates synthesized chemically inhibited only the pol.alpha activity in vitro. None of the compounds, including taxinine, influenced the activities of the other DNA polymerases, which are reportedly targeted by many pol.beta inhibitors. With both pol.alpha and beta, all of the compounds tested noncompetitively inhibited with respect to both the DNA template-primer and the dNTP substrate.