Bile duct-specific lectins, Dolichos biflorus agglutinin and peanut agglutinin, as probes in mouse hepatocarcinogenesis.
BACKGROUND
It is well established that alterations in the expression of cell surface glycoproteins occur during the course of tumorigenesis and can be detected immunohistochemically. However, no consistent markers of malignancy in mouse hepatocellular tumors have yet been identified.


METHODS
Lectin histochemistry, using three bile duct-specific lectins, Dolichos biflorus agglutinin (DBA), peanut agglutinin (PNA) and soybean agglutinin (SBA), and anti-epidermal keratin immunohistochemistry, was conducted on formalin-fixed, paraffin-embedded tissues of a spectrum of benign and malignant hepatocellular proliferative lesions of mice, including hepatocholangiocarcinomas. DBA- and PNA-binding glycoproteins in normal livers and in bile and liver tumors of mice were verified by SDS-PAGE and Western blot analysis.


RESULTS
Normal bile duct cells stained strongly with DBA but minimally to moderately with PNA and SBA. DBA-positive tumor cells were present in 96% of hepatocholangiocarcinomas, 89% of hepatocellular carcinomas, and 35% of hepatocellular adenomas. In comparison, 43% of hepatocholangiocarcinomas, 37% of hepatocellular carcinomas, and 24% of hepatocellular adenomas exhibited PNA staining. SBA did not specifically stain tumor cells. Normal hepatocytes and those in altered foci were consistently negative for these three lectins. Keratin-positive staining was found only in normal bile ductular cells and ductal elements in 70% of hepatocholangiocarcinomas. Electrophoresis and Western blot analysis demonstrated that, in normal livers, DBA and PNA bound to the 13- to 16-kDa and 27- to 30-kDa glycoproteins believed to be of bile duct cell origin and commonly present in hepatocellular adenomas, hepatocellular carcinomas, and hepatocholangiocarcinomas, with strongest expression in the last. In addition, hepatocholangiocarcinomas had the same high molecular mass glycoprotein (> 200 kDa) labeled with DBA as detected in bile.


CONCLUSIONS
Our results suggest that some malignant hepatocytes, especially in mouse hepatocholangiocarcinomas, have the potential of biliary differentiation. DBA is a sensitive marker for malignant hepatocytes in mice.
Takahashi
K
K
National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA.
Viviano
C J
CJ
Elwell
M R
MR
Bakewell
W E
WE
Kuwahara
M
M
Nakashima
N
N
Blackwell
B N
BN
Maronpot
R R
RR
D000236:Adenoma / Q000175:diagnosis; D000818:Animals; D001652:Bile Ducts / Q000737:chemistry* / Q000378:metabolism; D015197:Carcinogenicity Tests / Q000379:methods; D006528:Carcinoma, Hepatocellular / Q000175:diagnosis*; D018281:Cholangiocarcinoma / Q000175:diagnosis; D005260:Female; D007150:Immunohistochemistry; D007633:Keratins / Q000032:analysis; D037102:Lectins / Q000032:analysis* / Q000378:metabolism; D008113:Liver Neoplasms / Q000175:diagnosis*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D015335:Molecular Probes / Q000032:analysis*; D019887:Peanut Agglutinin; D037121:Plant Lectins; D011230:Precancerous Conditions / Q000175:diagnosis; D012189:Retrospective Studies
D037102:Lectins; D015335:Molecular Probes; D019887:Peanut Agglutinin; D037121:Plant Lectins; C036554:dolichos biflorus agglutinin; D007633:Keratins