rna pol ii phosphorylation

RNA polymerase II-IN-2 (compound 20iii), a potent inhibitor of RNA polymerase II (Pol II) with a K i value of 9.5 nM, exhibits cytotoxicity against cancer cells, demonstrating toxicity levels 2 and 5 times higher than α-amanitin in CHO and HEK293 cells, respectively [1].

RNA polymerase II-IN-1 (compound 19iv), an amatoxin, selectively inhibits RNA polymerase II (Pol II) with an IC50 of 36.66 nM and exhibits heightened cytotoxicity towards cancer cells while reducing toxicity in normal cells compared to α-Amanitin [1].

MFH290 is a novel cysteine (Cys)-directed covalent inhibitor of CDK12/13. MFH290 forms a covalent bond with Cys-1039 of CDK12, exhibits excellent kinome selectivity, inhibits the phosphorylation of serine-2 in the C-terminal domain (CTD) of RNA-polymerase II (Pol II), and reduces the expression of key DNA damage repair genes. Importantly, these effects were demonstrated to be CDK12-dependent as mutation of Cys-1039 rendered the kinase refractory to MFH290 and restored Pol II CTD phosphorylation and DNA damage repair gene expression. Consistent with its effect on DNA damage repair gene expression, MFH290 augments the antiproliferative effect of the PARP inhibitor olaparib.

CDK9-Cyclin T1 PPI-IN-1 (Compound B19) is a selective inhibitor of the CDK9-Cyclin T1 protein-protein interaction (PPI), suppressing cell proliferation in TNBC MDA-MB-231 cells with an IC50 of 0.044 μM and inducing apoptosis. This compound diminishes CDK9 transcriptional activity and downregulates phosphorylation of RNA Pol II CTD ser2. In vivo, CDK9-Cyclin T1 PPI-IN-1 effectively impedes tumor growth in a TNBC 4T1 mouse model [1].

Toyocamycin (Vengicide) is an adenosine analog produced by Actinomycetes, functioning as an XBP1 inhibitor and inhibiting IRE1α-induced ATP-dependent XBP1 mRNA cleavage (IC50: 80 nM), and induces apoptosis.