Uses
A cell-permeable benzothiazole compound that selectively inhibits RNA polymerase I-mediated pre-rRNA transcription (IC50 = 142, 113, 54, and 74 nM in HCT-116, A375, MIA PaCa-2, and BJ-hTert cells, respectively), but not Pol II-mediated c-myc transcription, by preventing TAF (TATA Binding Protein-/TBP-Associated Factor) SL1 and rDNA association, effectively inhibiting Pol I-dependent proliferation among 39 cancer cell lines (IC50<1 µM) in vitro. While Pol I inhibition by CX-5461 is shown to result in p53-dependent apoptosis in cancer cells of hematopoietic origin, cell death by CX-5461 treatment in solid tumors-derived A375 and MIA PaCa-2 cultures are primarily due to autophagy and senescence, but not apoptosis, induction. Shown to suppress A375 (50 mg/kg/d p.o.) and MIA PaCa-2 (50 mg/kg/3d p.o.) tumor expansion, as well as selectively induce p53-mediated cell death of Eμ-Myc lymphoma, but not normal B cells, in mice (50 mg/kg p.o.) in vivo.
Definition
ChEBI: CX-5461 is an organic heterotetracyclic compound that is 5-oxo-5H-[1,3]benzothiazolo[3,2-a][1,8]naphthyridine-6-carboxylic acid substituted by a 4-methyl-1,4-diazepan-1-yl group at position 2 and in which the carboxy group at position 6 is substituted by a [(5-methylpyrazin-2-yl)methyl]nitrilo group. An inhibitor of ribosomal RNA (rRNA) synthesis which specifically inhibits RNA polymerase I-driven transcription of rRNA in several cancer cell lines. It is currently in phase I/II clinical trials for advanced hematologic malignancies and triple-negative breast cancer with BRCA1/2 mutation. It has a role as an antineoplastic agent, an apoptosis inducer and an EC 2.7.7.6 (RNA polymerase) inhibitor. It is a diazepine, an organic heterotetracyclic compound, a member of pyrazines, a secondary carboxamide and a naphthyridine derivative.
General Description
A cell-permeable benzothiazole compound that selectively inhibits RNA polymerase I-mediated pre-rRNA transcription (IC50 = 142 nM in HCT-116), but not Pol II-mediated c-myc transcription, by preventing TAF SL1 and rDNA association). Effectively inhibits Pol I-dependent proliferation among 39 cancer cell lines (IC50<1 μM) in vitro and suppresses A375 (50 mg/kg/d p.o.) and MIA PaCa-2 (50 mg/kg/3d p.o.) tumor expansion in vivo.
Biological Activity
cx-5461 is a potent and orally bioavailable small-molecule inhibitor of rrna synthesis that specifically inhibits rna polymerase (pol) i-driven transcription with ic50 value of 142 nm. cx-5461 exhibits antiproliferative activity against human pancreatic tumor cells mia paca-2, human melanoma cells a375 and colorectal carcinoma cells hct-116 with ec50 values of 74, 58, and 167 nmol/l, respectively. [1].cx-5461 was revealed to inhibit pol i transcription via promoting the stabilization of p53. in addition, cx-5461 has been demonstrated to induce autophagy and senescence but not apoptosis in mia paca-2 and a375 cell lines.
Biochem/physiol Actions
Cell permeable: yes
in vivo
cx-5461 has shown to suppress tumor volume in both mia paca-2 and a375 derived xenograft mice models [1].
References
[1] drygin d1, lin a, bliesath j, ho cb, o'brien se, proffitt c, omori m, haddach m, schwaebe mk, siddiqui-jain a, streiner n, quin je, sanij e, bywater mj,hannan rd, ryckman d, anderes k, rice wg. targeting rna polymerase i with an oral small molecule cx-5461 inhibits ribosomal rna synthesis and solid tumor growth. cancer res. 2011 feb 15;71(4):1418-30
