Frequent activation of mitogen-activated protein kinase relative to Akt in extrahepatic biliary tract cancer.

BACKGROUND

Lack of effective adjuvant therapy against advanced extrahepatic biliary tract carcinoma (BTC) requires that new therapeutic methods, such as molecular targeted therapy, be developed. The mitogen-activated protein kinase (MAPK) and Akt signaling pathways, which activate cell proliferation and suppress apoptosis, respectively, may function as important targets for such therapies. The aim of this study was to examine the expression patterns of phosphorylated MAPK (p-MAPK) and phosphorylated Akt (p-Akt) proteins in BTC cell lines and clinical specimens.

METHODS

Expression of p-MAPK and p-Akt proteins in four human BTC cell lines and in frozen sections of 20 advanced extrahepatic BTC specimens was analyzed by Western blotting. Thirty formalin-fixed BTC specimens were immunohistochemically stained for p-MAPK and p-Akt using labeled streptavidin-biotin conjugates.

RESULTS

Expression of p-MAPK was observed in three of four (75%) BTC cell lines, whereas no expression of p-Akt was observed. Twenty-three of 30 formalin-fixed specimens stained positive for p-MAPK (77%), whereas only 47% stained positively for p-Akt. Expression of p-MAPK relative to that of p-Akt was also seen more frequently in the frozen specimens.

CONCLUSIONS

The results of this study suggest that MAPK is activated more frequently than Akt in extrahepatic biliary tract carcinoma.