Detailed tissue expression of bcl-2, bax, bak and bcl-x in the normal human pancreas and in chronic pancreatitis, ampullary and pancreatic ductal adenocarcinomas.

BACKGROUND: The aim of this study was to evaluate expression of the bcl-2 family of apoptosis regulating proteins in normal and diseased human pancreatic tissues.
METHOD: Expression of bcl-2, bax, bcl-x, bak and p53 was determined in formalin-fixed paraffin wax-embedded archival specimens of normal pancreatic tissue (n = 7), chronic pancreatitis (n = 7), pancreatic ductal adenocarcinoma (n = 23) and ampullary cancer (n = 7) by immunohistochemistry using specific antibodies.
RESULTS: In normal pancreas and chronic pancreatitis tissues, bcl-2, bax and bcl-x were predominantly expressed in ductal epithelial cells while p53 was not detected. In pancreatic ductal adenocarcinoma and ampullary cancer, bcl-2 was not detected compared with expression seen in normal acini (p < 0.01), minor (p < 0.001) and major ducts (p < 0.01), bax expression was reduced with respect to minor ducts (p < 0.01) but no different from normal acini or major ducts. bak and bcl-x were more strongly expressed in malignant epithelia compared with acini and major ducts but reduced when compared with minor ducts (p < 0.01). Overexpression of p53 was identified in 11 (48%) of 23 pancreatic adenocarcinomas and 4 (57%) of 7 ampullary cancers. Differential survival of individual patients was predicted by the relative level of bcl-x expression but not bax or bak, such that strong expression of bcl-x was associated with a median postoperative survival of 171 days when compared with 912 days for diminished expression (p < 0.001) of bcl-x.
CONCLUSION: Pancreatic and ampullary cancer are associated with absent bcl-2 expression. bax, bak and bcl-x expression was reduced compared with normal minor ducts whilst bak and bcl-x expression was increased when compared with major ducts. bcl-x expression correlates with survival following resection and may represent a potential prognosis marker.