Insulin

AIM: This study is to determine if four endogenous growth inhibitors (i.e. four car-diac hormones) can inhibit the activity of extracellular-signal regulated kinases 1/2 (ERK 1/2) stimulated by endogenous growth promoters i.e. insulin and epidermal growth factor (EGF). METHODS: The phosphorylation of ERK 1/2 was measured with Western blots, while DNA synthesis was measured by bromodeoxyuridine incorporation. RESULTS: These four peptide hormones, i.e. vessel dilator, kaliuretic peptide, long acting natriuretic peptide, and atrial natriuretic peptide decreased insulin’s (10 µM) 66 % enhanced phosphorylation in human prostate adenocarcinoma cells to 10%, 8%, 24%, and 13 % above non-stimulated ERK 1/2 activity, respectively. The EGF’s (50 ng/ml) 66 % enhanced phosphorylation of ERK 1/2 in human prostate cancer cells was inhibited to-11 % (i.e. 117 % decrease), 4%, 13 % and 16 % by vessel dilator, atrial natri-uretic peptide, long acting natriuretic peptide, and kaliuretic peptide compared to non-stimulated ERK 1/2 activity, respectively. In human pancreatic cancer cells insulin and epidermal growth factor stimulated ERK 1/2 to a larger extent, i.e., 98 % and 472%