Constitutive hypophosphorylation of extracellular signal-regulated kinases-1/2 and down-regulation of c-Jun in human gastric adenocarcinoma

Hyperphosphorylation of extracellular signal-regulated protein kinases-1/2 (ERK1/2) is known to promote cancer cell proliferation. We therefore investigated the constitutive phosphorylation levels of ERK1/2 and the expression of its downstream targets c-Fos, c-Jun, and cyclooxygenase-2 (COX-2) in biopsied human gastric cancer tissues. Results showed that ERK1/2 phosphorylation and c-Jun expression were significantly lowered in gastric cancer compared with the non-cancer adjacent tissues. The expression of c-Fos, however, was not altered while COX-2 was significantly up-regulated. To conclude, we demonstrate that hypophosphorylation of ERK1/2 may occur in gastric cancer. Such discovery may have implication in the application of pathway-directed therapy for this malignant disease.