Claudin-1, -2, -3, -4, -7, -8, and -10 protein expression in biliary tract cancers

Abstract

Biliary tract cancers are relatively common malignant gastrointestinal tumors in the elderly. Claudins are integral components of tight junctions that play important roles in maintaining epithelial cell polarity, controlling paracellular diffusion, and regulating cell growth and differentiation. The expression profile of claudins has been extensively characterized, but few reports exist on their expression in the normal and neoplastic biliary tract. Our aim was therefore to study claudins by IHC reactions in normal and neoplastic biliary tract samples. We detected that claudin expressions differ in the normal sample groups: the normal gallbladder strongly expressed claudin-2, -3, -4, and -10, but only weak reactions were seen in normal intrahepatic bile ducts. Although each cancer type expressed several claudins with various intensities, only claudin-4 presented especially strong immunoreactions in extrahepatic bile duct cancers and gallbladder carcinomas, whereas claudin-1 and -10 presented in intrahepatic bile duct cancers. Comparing the normal and carcinoma groups, the most significant decrease was detected in the expression of claudin-10. In conclusion, the expression pattern of claudins is different in the various parts of the normal and neoplastic biliary tract; moreover, an unequivocal decrease was detected in the carcinomas compared with their corresponding normal samples. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.

Figure 1

An overview of claudin immunoreaction results. Median intensity (Int) and mean percent positivity (Pos%) scores of the normal and tumor sample groups are represented with colors and patterns, respectively (for color code, see legend in the figure). Cancers are compared with their corresponding normal epithelia in top panel, whereas the cancer groups are compared with one another in bottom panel. Significant differences are marked by asterisks. NIBD, normal intrahepatic bile duct; NEBD, normal extrahepatic bile duct; NGB, normal gallbladder; IBDC, intrahepatic bile duct cancer; EBDC, extrahepatic bile duct cancer; GBC, gallbladder cancer. (*), nearly significant (p=0.056); *, significant at 0.05>p>0.01; **, significant at 0.01>p>0.001; ***, significant at p<0.001.

Figure 2

Discriminant analysis. The six studied groups (NIBD, NEBD, NGB, IBDC, EBDC, GBC) are neatly separated by discriminant analysis based on claudin-1, -2, -3, -4, -7, -8, and -10 immunoreaction intensity and percent immunopositivity data.

Figure 3

Claudin-2 and -3 immunoreactions in the NGB, GBC, NIBD, and IBDC groups. Claudin-2 was most intensely expressed in the normal gallbladder and significantly diminished in GBC compared with NGB. Claudin-3 was strongly expressed on the normal gallbladder epithelium, but only weak expression was seen in the normal intrahepatic bile ducts. A significant drop was found in claudin-3 positivity in the case of gallbladder and intrahepatic bile duct carcinomas compared with their corresponding normal regions. Bar = 0.05 mm.

Figure 4

Claudin-10 immunoreactions in the NEBD, NGB, NIBD, EBDC, GBC, and IBDC groups. Claudin-10 decreased significantly in all corresponding pairs of normal vs carcinoma comparisons, although it was relatively strongly expressed in IBDC compared with both EBDC and GBC. Bar = 0.05 mm.

Figure 5

Claudin-1 and -4 immunoreactions in EBDC, GBC, and IBDC. Claudin-1 immunostaining was more intense, although non-significantly, in IBDC compared with both EBDC and GBC. Claudin-4 was most intense in the extrahepatic bile duct carcinomas and significantly fainter in IBDC and GBC. Bar = 0.05 mm.