title: Combined analysis of Rac1, IQGAP1, Tiam1 and E-cadherin expression in gastric cancer.
abstract: Rho GTPases are a family of major regulators of E-cadherin-mediated cell adhesion that are implicated in the carcinogenic process by deregulated expression of the family members itself or of upstream modulators or downstream effectors. Combined investigation of the Rho GTPase Rac1, the effector protein IQGAP1 and the activator Tiam1 in relation to expression or mutation of E-cadherin in gastric adenocarcinomas has not been reported. The aim of the study was to determine the expression and prognostic significance of Rac1, IQGAP1, Tiam1 and E-cadherin in gastric adenocarcinomas. Gastric carcinomas of 76 patients were investigated immunohistochemically in a tissue microarray study for expression of Rac1, IQGAP1, Tiam1 and E-cadherin. Correlations with clinical and follow-up data were examined. Moderate or strong reactivity for Rac1 was observed in 46% and for Tiam1 in 56% of tumors. Expression of IQGAP1 was present in 59% and of E-cadherin in 87% of tumors. While Rac1 and E-cadherin expression were not related to prognosis, a trend was observed between a lack of IQGAP1 expression (log-rank 0.088) as well as presence of Tiam1 (log-rank 0.097) and favorable prognosis in Kaplan-Meier survival analysis. Expression of Rac1 was positively linked to IQGAP1 expression (P=0.007, r=0.343) and tended to be inversely associated with expression of E-cadherin (P=0.055, r=-0.245). In conclusion, we observed deregulated expression of Rac1, IQGAP1, Tiam1 and E-cadherin in gastric cancer. We present evidence that either upregulation (for Rac1 and IQGAP1) or downregulation (for Tiam1 and E-cadherin) occurs. Rac1 and E-cadherin expression were not related to prognosis, while trends pointing to favorable prognosis of patients with Tiam1 expression and a lack of IQGAP1 expression were observed. These results indicate that the investigated regulators of E-cadherin-mediated cell adhesion play a role in gastric carcinogenesis.
authors.affiliation: Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Institut für Pathologie, Neuherberg, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Walch
authors.forename: Stefan
authors.initials: S
authors.lastname: Seidl
authors.forename: Christine
authors.initials: C
authors.lastname: Hermannstädter
authors.forename: Sandra
authors.initials: S
authors.lastname: Rauser
authors.forename: Joëlle
authors.initials: J
authors.lastname: Deplazes
authors.forename: Rupert
authors.initials: R
authors.lastname: Langer
authors.forename: Claus Hann
authors.initials: CH
authors.lastname: von Weyhern
authors.forename: Mario
authors.initials: M
authors.lastname: Sarbia
authors.forename: Raymonde
authors.initials: R
authors.lastname: Busch
authors.forename: Marcus
authors.initials: M
authors.lastname: Feith
authors.forename: Sonja
authors.initials: S
authors.lastname: Gillen
authors.forename: Heinz
authors.initials: H
authors.lastname: Höfler
authors.forename: Birgit
authors.initials: B
authors.lastname: Luber
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis; D015820:Cadherins / Q000096:biosynthesis*; D005260:Female; D020662:Guanine Nucleotide Exchange Factors / Q000096:biosynthesis*; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D013274:Stomach Neoplasms / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D000075684:T-Lymphoma Invasion and Metastasis-inducing Protein 1; D046888:Tissue Array Analysis; D020830:rac1 GTP-Binding Protein / Q000096:biosynthesis*; D020703:ras GTPase-Activating Proteins / Q000096:biosynthesis*
chemical_list: D014408:Biomarkers, Tumor; D015820:Cadherins; D020662:Guanine Nucleotide Exchange Factors; C101203:IQ motif containing GTPase activating protein 1; C107953:RAC1 protein, human; D000075684:T-Lymphoma Invasion and Metastasis-inducing Protein 1; C087334:TIAM1 protein, human; D020703:ras GTPase-Activating Proteins; D020830:rac1 GTP-Binding Protein