Inactivation of the E-cadherin gene in primary gastric carcinomas and gastric carcinoma cell lines.
We investigated the E (epithelial)-cadherin gene for mutations and loss of heterozygosity (LOH) in 24 primary gastric carcinomas (12 differentiated and 12 undifferentiated types, including 3 signet-ring cell carcinomas), as well as 4 gastric carcinoma cell lines of the undifferentiated type (MKN-45, GCIY, HGC-27 and GT3TKB). We utilized PCR-SSCP and RT-PCR followed by direct sequencing to detect gene mutations and skipped exons, and RT-PCR-SSCP to examine LOH. In primary carcinomas, gene mutations or skipped exons were detected in 4 of 9 (44%) undifferentiated carcinomas of the scattered type, including 2 signet-ring cell carcinomas, and in none of the 3 undifferentiated carcinomas of the adherent type and 12 differentiated carcinomas. Demonstrated mutations of the E-cadherin gene included an 18 bp deletion (codon 418-423) and a 3 bp deletion (codon 400, calcium-binding domain), both located in exon 9. Skipping of exon 9 with a 1 bp insertion at codon 337, and skipping of exon 8 with a 1 bp deletion at codon 336, also were detected. LOH was confirmed in all of the carcinomas in which gene mutations or skipped exons (3/3 informative cases) were demonstrated. The MKN-45 cell line exhibited an 18 bp deletion at the exon 6-intron 6 boundary with loss of the wild-type allele, and 2 of the remaining 3 cell lines (HGC-27 and GT3TKB) had lost expression without detectable structural alteration of the E-cadherin gene. These data provide support for classic two-hit inactivation of the E-cadherin gene in a high percentage of undifferentiated carcinomas of the scattered type.
Tamura
G
G
Department of Pathology, Iwate Medical University School of Medicine, Uchimaru, Morioka.
Sakata
K
K
Nishizuka
S
S
Maesawa
C
C
Suzuki
Y
Y
Iwaya
T
T
Terashima
M
M
Saito
K
K
Satodate
R
R
D000483:Alleles; D001483:Base Sequence; D015820:Cadherins / Q000096:biosynthesis* / Q000235:genetics*; D002277:Carcinoma / Q000235:genetics* / Q000378:metabolism*; D005091:Exons; D017353:Gene Deletion; D015972:Gene Expression Regulation, Neoplastic; D006579:Heterozygote; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D018807:Polymorphism, Single-Stranded Conformational; D013274:Stomach Neoplasms / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D015820:Cadherins