title: Interruption of RNA processing machinery by a small compound, 1-[(4-chlorophenyl)methyl]-1H-indole-3-carboxaldehyde (oncrasin-1).
abstract: Protein kinase Ciota (PKCiota) is activated by oncogenic Ras proteins and is required for K-Ras-induced transformation and colonic carcinogenesis in vivo. However, the role of PKCiota in signal transduction and oncogenesis is not clear. We recently identified a small molecule, designated 1-[(4-chlorophenyl)methyl]-1H-indole-3-carboxaldehyde (oncrasin-1), that can selectively kill K-Ras mutant cancer cells and induce abnormal nuclear aggregation of PKCiota in sensitive cells but not in resistant cells. To determine the causes and biological consequences of PKCiota aggregates in the nucleus, we analyzed the effect of oncrasin-1 on proteins involved in DNA repair and RNA processing. Our results showed that oncrasin-1 treatment led to coaggregation of PKCiota and splicing factors into megaspliceosomes but had no obvious effects on the DNA repair molecule Rad51. Moreover, oncrasin-1 treatment suppressed the phosphorylation of the largest subunit of RNA polymerase II and the expression of intronless reporter genes in sensitive cells but not in resistant cells, suggesting that suppression of RNA transcription is a major effect of oncrasin-1 treatment. Studies with cultured cells or with recombinant proteins showed that oncrasin-1 can disrupt the interaction of PKCiota and cyclin-dependent protein kinase 9/cyclin T1 complex, which is known to phosphorylate the largest subunit of RNA polymerase II and is required for RNA transcription. Together, our results suggest that oncrasin-1 suppresses the function of RNA processing machinery and that PKCiota might be involved in the biological function of RNA processing complexes.
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Guo
authors.forename: Shuhong
authors.initials: S
authors.lastname: Wu
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Rui-yu
authors.initials: RY
authors.lastname: Wang
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Wei
authors.forename: Jinsong
authors.initials: J
authors.lastname: Liu
authors.forename: Bingliang
authors.initials: B
authors.lastname: Fang
mesh_terms: D045744:Cell Line, Tumor; D056906:Cyclin T; D042863:Cyclin-Dependent Kinase 9 / Q000378:metabolism; D016213:Cyclins / Q000378:metabolism; D004354:Drug Screening Assays, Antitumor; D017930:Genes, Reporter; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D007527:Isoenzymes / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000378:metabolism; D020836:Protein Structure, Quaternary; D021381:Protein Transport / Q000187:drug effects; D012319:RNA Polymerase II / Q000037:antagonists & inhibitors; D012323:RNA Processing, Post-Transcriptional / Q000187:drug effects*; D016601:RNA-Binding Proteins / Q000378:metabolism; D051135:Rad51 Recombinase / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism; D000068103:Serine-Arginine Splicing Factors; D014158:Transcription, Genetic / Q000187:drug effects; D000099293:Protein Kinase C-lambda
chemical_list: D056906:Cyclin T; D042863:Cyclin-Dependent Kinase 9; D016213:Cyclins; D007211:Indoles; D007527:Isoenzymes; D008156:Luciferases; D009687:Nuclear Proteins; D011493:Protein Kinase C; D012319:RNA Polymerase II; D016601:RNA-Binding Proteins; D051135:Rad51 Recombinase; D012261:Ribonucleoproteins; D000068103:Serine-Arginine Splicing Factors; D000099293:Protein Kinase C-lambda; C503684:CCNT1 protein, human; C532252:oncrasin-1; C073288:SRSF2 protein, human; C467969:CDK9 protein, human; C495153:RAD51 protein, human