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Synergistic proliferative effects of human CCKB receptor in Swiss 3T3 cells
SYNAPTIC CELLS
VESICLE
PROTEIN 2 (SV2) IN HUMAN NORMAL AND NEOPLASTIC
Portela-Gomes, Guida M Centre of Nutrition, University
NEUROENDOCRINE
of Lisbon, Portugal
Synaptic vesicle protein 2 (SV2), previously reported in the nervous system, is here demonstrated in human neuroendocrine (NE) cells in different endocrine organs - gastrointestinal tract and pancreas, anterior pituitary gland, thyroid C cells, parathyroid chief cells and adrenal medulla. Ultrastructural studies showed SV2 labelling in secretory granules. Comparison of SV2 with the NE cell markers chromogranin A (CgA) and synaptophysin (Sy), showed more SV2 and Sy than CgA-immunoreactive cells in the antrum and pancreas, whereas the converse was found in the intestinal tract. In the intestinal tract more SV2 than Sy-immunoreactive cells were observed. SV2 immunoreactivity occurred in all NE tumours examined - foregut carcinoids (stomach and bronchial carcinoids, islet cell tumours), midgut carcinoids, hindgut carcinoids, medullary thyroid carcinoma, anterior pituitary tumours and pheochromcytomas. In hindgut carcinoids, SV2 was a more sensitive NE marker than CgA (negative) and Sy (weakly positive). In conclusion, SV2 is a broad NE cell marker, of special importance for hindgut carcinoids.
SYNERGISTIC
PROLIFERATIVE
EFFECTS OF HUMAN CCKB RECEPTOR
IN SWISS 3T3 CELLS
Zhukova, Elena; Sinnett-Smith, Jim; Afshar, Ali R; Young, Steve; Wong, Helen; Walsh, John H; Rozengurt, Enrique UCLA School of Medicine, Los Angeles, CA, USA The CCKB/gastrin receptor plays an important role in the regulation of gastric cell proliferation in vivo. A number of the cellular model systems have been utilized to unravel the signal transduction pathways activated by CCK and gastrin via CCKB/gastrin receptor in vitro, but a high-efficiency system has not, as yet, been developed. A retroviral gene transfer system was used to stably co-transfect CCKB/gastrin receptor and Green Fluorescent Protein (GFP) in Swiss 3T3 cells. After GFP sorting intracellular Ca++ responses to CCK were obtained in greater than 99% of cells compared to 75-90% before GFP sorting. Agonist-activation of the CCKB/gastrin receptor induced a striking dose-dependent stimulation of DNA synthesis in transfected Swiss 3T3 cells. In the presence of insulin (1 microgram/ml), addition of 50 nM CCK or gastrin induced a 66.5 + 8.8 (mean + SEM, n=4 in 8 independent experiments) fold increase in cellular DNA synthesis, reaching a level similar to that achieved by stimulation with a saturating concentration of fresh serum, and much greater than the response to saturating concentrations of gastrin or insulin given separately. These data demonstrate that stimulation of CCKB/gastrin receptor in combination with insulin receptor exerts a potent synergistic effect on induction of DNA synthesis and that Swiss 3T3 cell system provides an excellent model to study signal transduction pathways activated by CCK and gastrin via the CCKB/gastrin receptor.
VESICLE
PROTEIN 2 (SV2) IN HUMAN NORMAL AND NEOPLASTIC
Portela-Gomes, Guida M Centre of Nutrition, University
NEUROENDOCRINE
of Lisbon, Portugal
Synaptic vesicle protein 2 (SV2), previously reported in the nervous system, is here demonstrated in human neuroendocrine (NE) cells in different endocrine organs - gastrointestinal tract and pancreas, anterior pituitary gland, thyroid C cells, parathyroid chief cells and adrenal medulla. Ultrastructural studies showed SV2 labelling in secretory granules. Comparison of SV2 with the NE cell markers chromogranin A (CgA) and synaptophysin (Sy), showed more SV2 and Sy than CgA-immunoreactive cells in the antrum and pancreas, whereas the converse was found in the intestinal tract. In the intestinal tract more SV2 than Sy-immunoreactive cells were observed. SV2 immunoreactivity occurred in all NE tumours examined - foregut carcinoids (stomach and bronchial carcinoids, islet cell tumours), midgut carcinoids, hindgut carcinoids, medullary thyroid carcinoma, anterior pituitary tumours and pheochromcytomas. In hindgut carcinoids, SV2 was a more sensitive NE marker than CgA (negative) and Sy (weakly positive). In conclusion, SV2 is a broad NE cell marker, of special importance for hindgut carcinoids.
SYNERGISTIC
PROLIFERATIVE
EFFECTS OF HUMAN CCKB RECEPTOR
IN SWISS 3T3 CELLS
Zhukova, Elena; Sinnett-Smith, Jim; Afshar, Ali R; Young, Steve; Wong, Helen; Walsh, John H; Rozengurt, Enrique UCLA School of Medicine, Los Angeles, CA, USA The CCKB/gastrin receptor plays an important role in the regulation of gastric cell proliferation in vivo. A number of the cellular model systems have been utilized to unravel the signal transduction pathways activated by CCK and gastrin via CCKB/gastrin receptor in vitro, but a high-efficiency system has not, as yet, been developed. A retroviral gene transfer system was used to stably co-transfect CCKB/gastrin receptor and Green Fluorescent Protein (GFP) in Swiss 3T3 cells. After GFP sorting intracellular Ca++ responses to CCK were obtained in greater than 99% of cells compared to 75-90% before GFP sorting. Agonist-activation of the CCKB/gastrin receptor induced a striking dose-dependent stimulation of DNA synthesis in transfected Swiss 3T3 cells. In the presence of insulin (1 microgram/ml), addition of 50 nM CCK or gastrin induced a 66.5 + 8.8 (mean + SEM, n=4 in 8 independent experiments) fold increase in cellular DNA synthesis, reaching a level similar to that achieved by stimulation with a saturating concentration of fresh serum, and much greater than the response to saturating concentrations of gastrin or insulin given separately. These data demonstrate that stimulation of CCKB/gastrin receptor in combination with insulin receptor exerts a potent synergistic effect on induction of DNA synthesis and that Swiss 3T3 cell system provides an excellent model to study signal transduction pathways activated by CCK and gastrin via the CCKB/gastrin receptor.