Nerve growth factor (NGF) as an autocrine or paracrine growth factor plays a critical role in the pathogenesis and progression of human pancreatic cancer. NGF is synthesized as a proform (proNGF) that, when cleaved, releases mature ligand (mNGF). proNGF and mNGF bind to high-affinity tyrosine kinase receptor A (TrkA) and low-affinity receptor p75 to different extents. Histamine is a potent stimulator of NGF in the inflammatory lesion as determined by ELISA. This has generally been attributed to the accumulation of mNGF. To determine the effect of histamine on nerve growth factor/receptor expression in human pancreatic cancer, the present study explored intracellular and extracellular NGF production and p75 and TrkA membrane receptor expression in the PANC-1, KMP-6 and PK-1 cell lines. Histamine enhanced NGF secretion and mRNA expression in PANC-1 and KMP-6 cells, but not in PK-1 cells. proNGF was revealed using Western blotting to be the predominant form of NGF, but was significantly reduced by histamine. p75 receptor binding was increased with histamine treatement, but no significant alteration was observed for TrkA. Proliferating cell nuclear antigen (PCNA), an important indicator of cell proliferation, was significantly reduced by histamine stimulation. H1 and H2 receptors were both observed in the pancreatic cancer cells, and the alterations induced by histamine were counteracted by H1 receptor antagonist pyrilamine; however, the H2 receptor subtype was excluded from this process. These results suggest that histamine induces distinct nerve growth factor/receptor responsiveness via H1 receptor-induced signaling, thus affecting pancreatic cancer cell proliferation.

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