Analysis of E-cadherin in diffuse-type gastric cancer using a mutation-specific monoclonal antibody.
In-frame deletions from the E-cadherin mRNA, coding for a homophilic cell adhesion molecule, are characteristic for diffuse-type gastric carcinomas. Using immunohistochemical analysis the mutant form cannot be distinguished from normal E-cadherin, making results difficult to interpret. In this study, a rat monoclonal antibody, designated E-cad delta 9-1, was generated against a peptide spanning the fusion junction region between exons 8 and 10. This new epitope is present in an E-cadherin variant that lacks exon 9 from the mRNA due to different splice-site gene mutations. Using Western blotting and immunohistochemistry of E-cadherin-transfected cells, we demonstrate that E-cad delta 9-1 specifically reacts with E-cadherin lacking exon 9 but not with the wild-type protein. No immunoreactivity was observed in 31 nontumorous and embryonal tissues analyzed. In gastric carcinoma specimens known to express mutant E-cadherin mRNA lacking exon 9, E-cad delta 9-1 targets exclusively tumor cells in routine formalin-fixed and paraffin-embedded material from biopsies, primary tumors, and lymph node metastases. In a retrospective series of 172 diffuse-type gastric carcinomas expressing E-cadherin, E-cad delta 9-1 reacted with 22 tumors (13%). This new tumor marker-monoclonal antibody system could open novel avenues for selective diagnosis and specific therapy of a subgroup of diffuse-type gastric cancer patients.
Becker
K F
KF
Technische Universität München, Klinikum rechts der Isar, Institut für Pathologie, München, Germany. kf.becker@lrz.tum.de
Kremmer
E
E
Eulitz
M
M
Becker
I
I
Handschuh
G
G
Schuhmacher
C
C
Müller
W
W
Gabbert
H E
HE
Ochiai
A
A
Hirohashi
S
S
Höfler
H
H
D000818:Animals; D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor; D015153:Blotting, Western; D015820:Cadherins / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D000939:Epitopes; D006801:Humans; D007150:Immunohistochemistry; D009154:Mutation; D012333:RNA, Messenger; D051381:Rats; D013274:Stomach Neoplasms / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology; D014162:Transfection; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor; D015820:Cadherins; D000939:Epitopes; D012333:RNA, Messenger