title: The CRKL gene encoding an adaptor protein is amplified, overexpressed, and a possible therapeutic target in gastric cancer.
abstract: BACKGROUND
  Genomic DNA amplification is a genetic factor involved in cancer, and some oncogenes, such as ERBB2, are highly amplified in gastric cancer. We searched for the possible amplification of other genes in gastric cancer.
  
  
  RESULTS
  A genome-wide single nucleotide polymorphism microarray analysis was performed using three cell lines of differentiated gastric cancers, and 22 genes (including ERBB2) in five highly amplified chromosome regions (with a copy number of more than 6) were identified. Particular attention was paid to the CRKL gene, the product of which is an adaptor protein containing Src homology 2 and 3 (SH2/SH3) domains. An extremely high CRKL copy number was confirmed in the MKN74 gastric cancer cell line using fluorescence in situ hybridization (FISH), and a high level of CRKL expression was also observed in the cells. The RNA-interference-mediated knockdown of CRKL in MKN74 disclosed the ability of CRKL to upregulate gastric cell proliferation. An immunohistochemical analysis revealed that CRKL protein was overexpressed in 24.4% (88/360) of the primary gastric cancers that were analyzed. The CRKL copy number was also examined in 360 primary gastric cancers using a FISH analysis, and CRKL amplification was found to be associated with CRKL overexpression. Finally, we showed that MKN74 cells with CRKL amplification were responsive to the dual Src/BCR-ABL kinase inhibitor BMS354825, likely via the inhibition of CRKL phosphorylation, and that the proliferation of MKN74 cells was suppressed by treatment with a CRKL-targeting peptide.
  
  
  CONCLUSIONS
  These results suggested that CRKL protein is overexpressed in a subset of gastric cancers and is associated with CRKL amplification in gastric cancer. Furthermore, our results suggested that CRKL protein has the ability to regulate gastric cell proliferation and has the potential to serve as a molecular therapy target for gastric cancer.
authors.affiliation: Department of Tumor Pathology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi Ward, Hamamatsu, Shizuoka 431-3192, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Natsume
authors.forename: Kazuya
authors.initials: K
authors.lastname: Shinmura
authors.forename: Hong
authors.initials: H
authors.lastname: Tao
authors.forename: Hisaki
authors.initials: H
authors.lastname: Igarashi
authors.forename: Masaya
authors.initials: M
authors.lastname: Suzuki
authors.forename: Kiyoko
authors.initials: K
authors.lastname: Nagura
authors.forename: Masanori
authors.initials: M
authors.lastname: Goto
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Yamada
authors.forename: Matsuyoshi
authors.initials: M
authors.lastname: Maeda
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Konno
authors.forename: Satoki
authors.initials: S
authors.lastname: Nakamura
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Sugimura
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D002877:Chromosomes, Human / Q000235:genetics; D000069439:Dasatinib; D005260:Female; D005784:Gene Amplification / Q000187:drug effects / Q000235:genetics*; D018628:Gene Dosage; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D058990:Molecular Targeted Therapy; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism; D010455:Peptides / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology / Q000627:therapeutic use; D013274:Stomach Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D013844:Thiazoles / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C082869:CRKL protein; D009687:Nuclear Proteins; D010455:Peptides; D011743:Pyrimidines; D013844:Thiazoles; D000069439:Dasatinib