ABSTRACT
Despite frequent KRAS mutation, the early molecular mechanisms of pancreatic ductal adenocarcinoma (PDAC) development have not been fully elucidated. By tracking a potential regulator of another feature of PDAC precursors, acquisition of foregut or gastric epithelial gene signature, we herein report that aberrant overexpression of ecotropic viral integration site 1 (EVI1) oncoprotein, which is usually absent in normal pancreatic duct, is a widespread marker across the full spectrum of human PDAC precursors and PDAC. In pancreatic cancer cells, EVI1 depletion caused remarkable inhibition of cell growth and migration, indicating its oncogenic roles. Importantly, we found that EVI1 upregulated KRAS expression through suppression of a potent KRAS suppressor, miR-96, in pancreatic cancer cells. Collectively, the present findings suggest that EVI1 overexpression and KRAS mutation converge on activation of the KRAS pathway in early phases of pancreatic carcinogenesis and propose EVI1 and/or miR-96 as early markers and therapeutic targets in this dismal disease.
Subject(s)
Carcinoma, Pancreatic Ductal/genetics , DNA-Binding Proteins/genetics , MicroRNAs/genetics , Pancreatic Neoplasms/genetics , Proto-Oncogene Proteins/genetics , Proto-Oncogenes/genetics , Transcription Factors/genetics , ras Proteins/genetics , Blotting, Western , Carcinoma, Pancreatic Ductal/metabolism , Cell Line, Tumor , Chromatin Immunoprecipitation , DNA-Binding Proteins/metabolism , Gene Expression Regulation, Neoplastic/genetics , Humans , Immunohistochemistry , MDS1 and EVI1 Complex Locus Protein , Mutation , Oligonucleotide Array Sequence Analysis , Oncogenes , Pancreatic Neoplasms/metabolism , Proto-Oncogene Proteins/metabolism , Proto-Oncogene Proteins p21(ras) , RNA, Small Interfering , Reverse Transcriptase Polymerase Chain Reaction , Signal Transduction/genetics , Transcription Factors/metabolism , Up-Regulation , ras Proteins/metabolismABSTRACT
A chloroplast-type ferredoxin containing two non-heme iron and two labile sulfur atoms per molecule was prepared from Aphanothece sacrum. Crystals were obtained by dialysis against 75% saturated a-monium sulfate solution, and belong to the tetragonal system with cell dimensions a = b = 92.2 A and c = 47.6 A, containing four molecules in an asymmetric unit. The electron density map at 5 A resolution was calculated by using the best phase angles determined by the single isomorphous replacement method coupled with the anomalous dispersion effect. An anomalous dispersion difference Fourier map for the native crystal clearly showed four humps corresponding to the iron atoms in an asymmetric unit. The electron densis surface.
