title: Gene expression profiling following constitutive activation of MEK1 and transformation of rat intestinal epithelial cells.
abstract: BACKGROUND
  Constitutive activation of MEK1 (caMEK) can induce the oncogenic transformation of normal intestinal epithelial cells. To define the genetic changes that occur during this process, we used oligonucleotide microarrays to determine which genes are regulated following the constitutive activation of MEK in normal intestinal epithelial cells.
  
  
  RESULTS
  Microarray analysis was performed using Affymetrix GeneChip and total RNA from doxycycline inducible RIEtiCAMEK cells in the presence or absence of doxycycline. MEK-activation induced at least a three-fold difference in 115 gene transcripts (75 transcripts were up-regulated, and 40 transcripts were down-regulated). To verify whether these mRNAs are indeed regulated by the constitutive activation of MEK, RT-PCR analysis was performed using the samples from caMEK expressing RIE cells (RIEcCAMEK cells) as well as RIEtiCAMEK cells. The altered expression level of 69 gene transcripts was confirmed. Sixty-one of the differentially expressed genes have previously been implicated in cellular transformation or tumorogenesis. For the remaining 8 genes (or their human homolog), RT-PCR analysis was performed on RNA from human colon cancer cell lines and matched normal and tumor colon cancer tissues from human patients, revealing three novel targets (rat brain serine protease2, AMP deaminase 3, and cartilage link protein 1).
  
  
  CONCLUSIONS
  Following MEK-activation, many tumor-associated genes were found to have significantly altered expression levels. However, we identified three genes that were differentially expressed in caMEK cells and human colorectal cancers, which have not been previously linked to cellular transformation or tumorogenesis.
authors.affiliation: Department of Gastroenterology, Honjo Daiichi General Hospital, Yurihonjo, Japan. koga-k@qb3.so-net.ne.jp
authors.forename: Koga
authors.initials: K
authors.lastname: Komatsu
authors.forename: F Gregory
authors.initials: FG
authors.lastname: Buchanan
authors.forename: Michiro
authors.initials: M
authors.lastname: Otaka
authors.forename: Mario
authors.initials: M
authors.lastname: Jin
authors.forename: Masaru
authors.initials: M
authors.lastname: Odashima
authors.forename: Yohei
authors.initials: Y
authors.lastname: Horikawa
authors.forename: Sumio
authors.initials: S
authors.lastname: Watanabe
authors.forename: Raymond N
authors.initials: RN
authors.lastname: Dubois
mesh_terms: D000818:Animals; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D003110:Colonic Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000201:enzymology / Q000473:pathology*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006801:Humans; D007422:Intestines / Q000201:enzymology / Q000473:pathology*; D048369:MAP Kinase Kinase 1 / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D051381:Rats; D015398:Signal Transduction; D013997:Time Factors
chemical_list: D048369:MAP Kinase Kinase 1