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Int J Clin Exp Pathol 2013;6(4):613-621

Original Article
An immunohistochemical study of primary signet-ring cell carcinoma of the stomach and
colorectum: II. expression of MUC1, MUC2, MUC5AC, and MUC6 in normal mucosa and in
42 cases

Tadashi Terada

Departments of Pathology, Shizuoka City Shimizu Hospital, Shizuoka, Japan

Received January 7, 2013; Accepted January 22, 2013; Epub March 15, 2013; Published April 1, 2013

Abstract: Expression of MUC apomucins has rarely been investigated in the signet-ring cell carcinoma (SRCC) of the stomach and
colorectum. The author examined immunohistochemically the expression status of MUC1, MUC2, MUC5AC, and MUC6 in 30 cases of gastric
SRCC and 12 cases of colorectal SRCC. The normal distribution of these MUC apomucins was also examined in the non-tumorous parts of
the stomach and colorectum. In normal tissues, the stomach epithelial cells consistently expressed MUC2, MUC5AC, MUC6, but consistently
not MUC1. In colorectum, cryptal epithelial cells consistently expressed MUC2, but consistently not MUC1, MUC5AC, and MUC6. The
expression pattern of the gastric SRCC was as follows: MUC1, 3/30 (10%); MUC2, 4/30 (13%); MUC5AC, 20/30 (67%), and MUC6 21/30 (70%).
The expression pattern of the colorectal SRCC was as follows: MUC1, 5/12 (42%); MUC2, 11/12 (92%); MUC5AC, 4/12 (33%); and MUC6, 0/12
(0%). Significant differences (p<0.05) were found in the expression of MUC1 (stomach SRCC 10% vs colorectal SRCC 42%), MUC2 (13% vs
92%), MUC5AC (67% vs 33%), and MUC6 (70% vs 0%). Thus, there was a significant tendency that primary gastric SRCC express MUC5AC
and MUC6 but not MUC1 and MUC2, while primary colorectal SRCC express MUC1, MUC2 and MUC5A, but not MUC6. These different
expressions of these MUC apomucins in gastric and colorectal SRCC seem useful to determine the primary site of metastatic SRCC and for
differential diagnosis of SRCC of other sites. In the gastric SRCC, the up-regulation of MUC1 and the down-regulation of MUC2, MUC5AC and
MUC6 appear to be associated with carcinogenesis, malignant potential, progression, and clinical behaviors in gastric SRCC. In the colorectal
SRCC, the up-regulation of MUC1 and MUC5AC may be associated with carcinogenesis, malignant potential, progression, and clinical
behaviors in colorectal SRCC. A comparative review of the present SRCC and presently reported ordinary adenocarcinoma and SRCC cases of
the stomach and colorectum was performed. (IJCEP1301015).

Keywords: Signet-ring cell carcinoma, MUC, mucins, stomach, colorectum, histopathology, immunohistochemistry

Address correspondence to: Dr. Tadashi Terada, Department of Pathology, Shizuoka City Shimizu Hospital, Miyakami 1231 Shimizu-Ku,
Shi-zuoka 424-8636, Japan. Tel: +81-54-336-1111; Fax: +81-54-334-1173; E-mail: piyo0111jp@yahoo.co.jp