Significance of aberrant (cytoplasmic/nuclear) expression of beta-catenin in pancreatoblastoma.
This study concerns the significance of aberrant (nuclear/cytoplasmic) expression of beta-catenin in pancreatoblastoma (PBL). On immunohistochemistry, all seven PBLs examined showed nuclear/cytoplasmic expression of beta-catenin, predominantly in the squamoid corpuscles (SCs). In areas with acinar/ductular differentiation, few tumour cells displayed nuclear/cytoplasmic expression of beta-catenin and more than half of the tumour cells showed membranous expression. Two out of five (40%) tumours examined showed missense mutations in codons 33 and 37 of exon 3 of the beta-catenin gene. No mutation of the adenomatous polyposis coli (APC) gene was detected in two of the remaining three tumours. Amplifiable DNA for APC analysis was not obtained from the one other tumour. Immunoreactivity for cyclin D1, one of the nuclear targets of beta-catenin, was found predominantly in the SCs of the seven tumours. In contrast, the Ki-67 labelling index was 2-4% (median 3%) in the SCs and 8-18% (median 12%) in the other areas, indicating a negative correlation with nuclear cyclin D1 reactivity. These results imply that in PBLs, nuclear/cytoplasmic accumulation of beta-catenin and overexpression of its target gene cyclin D1 are not associated with the induction of tumour cell proliferation. Nuclear/cytoplasmic accumulation of beta-catenin may be related to the morphogenesis of the SCs that are considered most characteristic for PBL.
Tanaka
Yukichi
Y
Division of Pathology, Kanagawa Children's Medical Center, Yokohama, Japan.
Kato
Keisuke
K
Notohara
Kenji
K
Nakatani
Yukio
Y
Miyake
Tetsumi
T
Ijiri
Rieko
R
Nishimata
Shigeo
S
Ishida
Yuji
Y
Kigasawa
Hisato
H
Ohama
Yokatsu
Y
Tsukayama
Choutatsu
C
Kobayashi
Yasutsugu
Y
Horie
Hiroshi
H
D002648:Child; D002675:Child, Preschool; D019938:Cyclin D1 / Q000032:analysis; D003598:Cytoskeletal Proteins / Q000032:analysis*; D004273:DNA, Neoplasm / Q000032:analysis; D005260:Female; D017491:Genes, APC; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D009154:Mutation; D009363:Neoplasm Proteins / Q000032:analysis*; D010190:Pancreatic Neoplasms / Q000235:genetics / Q000473:pathology*; D017422:Sequence Analysis, DNA / Q000379:methods; D015534:Trans-Activators / Q000032:analysis*; D051176:beta Catenin
C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; D015534:Trans-Activators; D051176:beta Catenin; D019938:Cyclin D1