The epidermal growth factor (EGF) receptor (EGFR) is activated by EGF and other EGF-like growth factors, including amphiregulin (AR). We characterized the localization and mitogenic action of AR in T3M4 and COLO-357 human pancreatic cancer cell lines and determined whether the presence of AR in human pancreatic cancers correlates with patient survival. Both T3M4 and COLO-357 cells were found to be extremely sensitive to AR, one-half maximal stimulation occurring at a concentration of 70 and 50 pM, respectively. The magnitude of the stimulatory effect was greater with AR than with EGF. Both cell lines exhibited AR immunostaining, which was present in a variable manner in the cytoplasm, nucleus and nucleoli. Immunohistochemical analysis of 62 pancreatic cancer tissues revealed the presence of nuclear and/or cytoplasmic AR immunoreactivity in the cancer cells. Cytoplasmic, but not nuclear localization of AR in the pancreatic cancer cells was associated with a statistically significant decrease in the post-operative survival period. The presence of EGFR alone in the cancer cells did not correlate with decreased survival, whereas coexpression of cytoplasmic AR and EGFR was associated with shorter survival. Distant metastases did not always exhibit cytoplasmic AR immunoreactivity. These findings point to the existence of an EGFR: AR autocrine loop in human pancreatic cancer which may contribute to its biological aggressiveness.

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