G protein-coupled receptor signaling in human ductal pancreatic cancer cells: Neurotensin responsiveness and mitogenic stimulation

Abstract

Neuropeptides and their corresponding G protein-coupled receptors (GPCRs) are increasingly implicated in the autocrine/paracrine stimulation of growth of human cancers. We report that neurotensin induced rapid Ca2+ mobilization from intracellular stores followed by Ca2+ influx in five human ductal pancreatic cancer cell lines: HPAF-II, Capan-1, Capan-2, PANC-1, and MIA PaCa-2. In addition, most cell lines exhibited Ca2+ responses to multiple neuropeptides including bombesin, bradykinin, cholecystokinin, and vasopressin and to bioactive lipids, including lysophosphatidic acid (LPA), that also act via GPCRs. The well-differentiated line HPAF-II responded to at least seven independent GPCR agonists. The concentrations of neurotensin required to induce half-maximal effects (EC50) in HPAF-II and PANC-1 cells were 5 and 8nM, respectively. Digital fluorescence image analysis to measure Ca2+ responses in single cells revealed that 90% or more of HPAF-II and PANC-1 cells responded to 10nM neurotensin. Addition of neurotensin to PANC-1 cells also induced rapid and dose-dependent extracellular-regulated protein kinase (ERK-1 and ERK-2) activation and subsequently, stimulated DNA synthesis. The signaling complexity of GPCRs uncovered by these studies reveals a new aspect in the biology of human pancreatic cancer and could offer the basis for new approaches to the treatment of this disease.

PKCμ prevents CD95-mediated apoptosis and enhances proliferation in pancreatic tumour cells

“…Thus, there may be a certain chance to reduce PKCm activity in malignant cells by appropriate antagonists (Heasley, 2001). This may also be applicable for pancreatic carcinoma cells being responsive to neuropeptides (Ryder et al, 2001).…”

The critical role and potential target of the autotaxin/lysophosphatidate axis in pancreatic cancer

“…Furthermore, the ATX/LPA axis stimulated DNA synthesis, proliferation, and migration of pancreatic cancer cells via GPCRs/ERK1/2 and Rho pathways. 104,105 However, further studies are needed to investigate the roles and mechanism of ATX in pancreatic cancer development and progression.…”

Lysophosphatidic acid induced nuclear translocation of nuclear factor-kB in Panc-1 cells by mobilizing cytosolic free calcium

“…LPA has a major role in migration of Panc-1 cells via phosphorylation of ERK [21] , but was reported to not act as mitogen in pancreatic cancer cell lines, Panc-1 cells and Bx-PC cells [21] . LPA also mobilized cytosolic calcium in Panc-1 cells as neuropeptides including neurotensin, bombesin, cholecystokinin, and vasopressin [22] . However, it is still unclear of roles of calcium mobilization in Panc-1 cells.…”