Ch. Chang et al., CHARACTERIZATION OF THE RELEASE OF CHOLECYSTOKININ FROM A MURINE NEUROENDOCRINE TUMOR-CELL LINE, STC-1, Biochimica et biophysica acta. Molecular cell research, 1221(3), 1994, pp. 339-347
The murine neuroendocrine cell line, STC-1, was found to contain 296.8
+/- 1.8 fmol of cholecystokinin-like immunoreactivity (CCK-LI) per mg
cell protein. Immunocytochemical stain of STG-1 cells maintained in m
onolayer culture indicated that CCK-LI activity was present in 93% of
the cells. Analysis by reverse-phase high-performance liquid chromatog
raphy indicated that STC-1 cells contained CCK-8 and an unidentified f
orm as the predominant storage form. However, only CCK-8 was released
into the culture medium upon stimulation by various secretagogues. The
release of CCK-LI from STC-1 cells was stimulated by dibutyryl cAMP,
forskolin, KCI, A23187, 4 beta-phorbol 12-myristate 13-acetate and lum
inal stimulants, e.g., sodium oleate, L-tryptophan, camostat and plaun
otol. The release of CCK-LI from STC-1 cells was also stimulated by a
neuropeptide, bombesin. The stimulatory effects of most of these agent
s were dose dependent. The stimulatory effects of dibutyryl cAMP, fors
kolin, and plaunotol were potentiated by 3-isobutyl-1-methyl xanthine,
while that of camostat was not. The results obtained in this study in
dicate that the release of CCK from STC-1 cells shares the same charac
teristics of CCK release as from the CCK-secreting cells of the intest
inal mucosa observed both in the dog and the rat in vitro and in vivo.
Thus, the cellular mechanism of CCK release which appears to be cAMP-
and Ca2+-dependent may be modulated by cellular protein kinase C acti
vity. The STC-1 cell appears to be a suitable model for studying the m
echanism of CCK release.