Gallbladder
carcinoma (GC) is a relatively uncommon
malignancy and is often caused by diagnostic difficulties in distinguishing the extension of
carcinoma in situ (CIS) from invasive
carcinoma along Rokitansky-Aschoff sinuses (RAS). The
laminin-5, a heterotrimer, is composed of alpha-3, beta-3 and gamma-2 chains. The gamma-2 chain is expressed in various invasive
carcinoma cells. There are numerous reports that have described that laminin-5-gamma-2 is associated with tissue invasion in many organs. However, few studies are found in gallbladder
carcinoma. To clarify the relationship between laminin-5-gamma-2 chain (LN-5) expression and the development of GCs, we performed an immunohistochemical study of 93 GCs. Cases were classified into three groups: CIS with/without the extension along RAS (Group A; n=17),
carcinoma invading mucosa or muscular layer (Group B; n=5) and
carcinoma invading beyond perimuscular connective tissue (Group C; n=71). The immunohistochemical intracytoplasmic expression was detected in the invasive fronts of the
tumor. In the invasive components of Group B and C, LN-5 was expressed in 100 and 97% of cases, respectively, whereas in the CIS lesions of GCs, expression was not observed in Group A. LN-5 expression in the GCs tended to increase as
tumors developed, which may be an
indicator of the potential invasiveness of the
tumor. Our results indicate that, in GCs, a strong intracytoplasmic expression of LN-5 was identified in the
cancer cells whether in situ they extend along RAS or invading stroma.