A functional in vitro model to examine signaling mechanisms in gastrin-mediated human cell growth.
Gastrin (G-17) is a trophic hormone with a high affinity for the cholecystokinin-B receptor (CCK-BR); the mechanisms linking receptor binding and activation of downstream events to cell growth are not known, and these studies have been hampered by the lack of a cell model. We have established a pancreatic carcinoid cell line, BON, which produces a number of gut hormones; however, these cells lack native CCK-BR. The purpose of our study was to develop a model cell line containing the CCK-BR and to characterize the cellular mechanisms involved in gastrin regulation of human cell growth. BON cells were transfected with an expression plasmid containing the human CCK-BR, and stable clones were selected using G418. Functional CCK-BR was confirmed by reverse transcriptase-polymerase chain reaction, 125I-gastrin binding, and mobilization of intracellular calcium ([Ca2+]i) in response to G-17. Stable transfectants were treated with G-17 (+/-) the CCK-BR antagonist, L365,260 (L-60); growth was assessed using a Coulter counter. G-17 stimulated the growth of the stable clones, whereas the selective CCK-BR antagonist, L-60, abolished this G-17-mediated trophic effect. We have shown that G-17, acting through the CCK-BR, mobilizes [Ca2+]i as a second messenger and stimulates cell growth. Our unique BON cell line, stably transfected with the human CCK-BR, provides a novel paradigm to further delineate signaling mechanisms in gastrin regulation of human cell growth.
Kim
H J
HJ
Department of Surgery, The University of Texas Medical Branch, Galveston, TX 77555-0527, USA.
Evers
B M
BM
Banker
N A
NA
Hellmich
M R
MR
Townsend
C M
CM
D002455:Cell Division / Q000502:physiology*; D002460:Cell Line; D002478:Cells, Cultured; D005755:Gastrins / Q000502:physiology*; D006801:Humans; D043887:Receptor, Cholecystokinin B / Q000502:physiology; D015398:Signal Transduction
D005755:Gastrins; D043887:Receptor, Cholecystokinin B