DRB

DRB (53-85-0) is a classic inhibitor of transcription by RNA polymerase II.A relatively selective inhibitor of Cdk9 (IC50=3 μM), the kinase of the positive transcription elongation factor b (P-TEF-b) required for processive transcription elongation by RNA polymerase II.1,2Also inhibits casein kinase II, IC50=4-10 μM.3Suppresses the SIRT1/CK2α pathway and enhances the radiosensitivity of human cancer cells.4Kinase-independent activities of Cdk9 such as glucocorticoid receptor modulation are not inhibited by DRB.5

White Solid

5,6-Dichlorobenzimidazole 1-β-D-ribofuranoside has been used:

• as an inhibitor of RNA polymerase II in mouse melanoma cells
• for the inhibition of cyclin D1 mRNA synthesis in human prostate epithelial cell lines
• in the inhibition of interleukin-2 gene transcription in Jurkat cells

DRB is an inhibitor of RNA synthesis (causes premature termination of transcription).

Inhibits casein kinase II and blocks RNA synthesis. An adenosine analog.5,6-Dichlorobenzimidazole riboside is used as an inhibitor of RNA Polymerase II. It is nucleoside analogue and used in research to study the mechanisms of cellular regulation. Further, it inhibits some protein kinases.

5,6-Dichlorobenzimidazole 1-β-D-ribofuranoside (DRB), a nucleoside analog that halts mRNA synthesis by phosphorylation of the C-terminal domain of RNA polymerase II, making it inactive. It also interferes with the DNA topoisomerase II, may modulate response to cytokines and blocks the human immunodeficiency virus (HIV) via RNA modification. It also inhibits cyclin-dependent kinases (CDKs) 7 and 9 and favors apoptosis in leukemic cells. It may serve as a therapeutic agent in treating cancer.

[1] SONJA BAUMLI L N J Jane A Endicott. Halogen bonds form the basis for selective P-TEFb inhibition by DRB.[J]. Chemistry & biology, 2010: 931-936. DOI:10.1016/j.chembiol.2010.07.012
[2] YUKI YAMAGUCHI  Hiroshi H  Tadashi Wada. Interplay between positive and negative elongation factors: drawing a new view of DRB[J]. Genes to Cells, 2001, 3 1: 9-15. DOI:10.1046/j.1365-2443.1998.00162.x
[3] ZANDOMENI R O. Kinetics of inhibition by 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole on calf thymus casein kinase II.[J]. Biochemical Journal, 1989, 262 2: 469-473. DOI:10.1042/bj2620469
[4] ZHI-QIANG WANG. Inhibition of P-TEFb by DRB suppresses SIRT1/CK2α pathway and enhances radiosensitivity of human cancer cells.[J]. Anticancer research, 2014, 34 12: 6981-6989.
[5] RONG ZHU, *. A Kinase-Independent Activity of Cdk9 Modulates Glucocorticoid Receptor-Mediated Gene Induction[J]. Biochemistry Biochemistry, 2014, 53 11: 1753-1767. DOI:10.1021/bi5000178