Differential expression of gastrin, cholecystokinin-A and cholecystokinin-B receptor mRNA in human pancreatic cancer cell lines.
BACKGROUND
It has been assumed that gastrin stimulates the growth of pancreatic cancer in an autocrine way through co-expression of gastrin and the cholecystokinin-B receptor (CCK-BR). However, pancreatic cancer cell lines established directly from patients have revealed a great heterogeneity in cell proliferation when exposed to CCK, gastrin and their receptor antagonists. The aim of this study was therefore to examine co-expression of CCK-A and CCK-B receptor (CCK-AR and CCK-BR), and gastrin mRNA as well as the secretion of CCK and gastrin peptides in these cell lines.


METHODS
Fourteen cell lines were established from primary pancreatic cancers or their metastases. Total RNA was isolated from the cell lines and reverse-transcribed into single-stranded cDNA. A PCR technique based on Taq polymerase-antibody interaction and CCK-AR, CCK-BR and gastrin-specific primers, followed by Southern blot analysis, were the methods used. The incubation mediums were analysed for the presence of secreted CCK/proCCK and gastrin/progastrin peptides by specific radioimmunoassays (RIA).


RESULTS
By means of nested Reverse-Transcribed Polymerase Chain Reaction (nested RT-PCR), combined with Southem blot analysis of the PCR amplified products, CCK-AR and gastrin mRNA co-expression was detected in cell lines LPC-6p and LPC-10m, whereas CCK-BR and gastrin mRNA could be detected in cell lines LPC-8p and LPC-12m. A low level of secreted CCK peptides was detected in cell line LPC-6p, which also expressed CCK-AR mRNA. In no other cases were CCK or gastrin peptides detected in the cell culture mediums.


CONCLUSIONS
The lack of CCK-BR and gastrin mRNA co-expression, and not detectable levels of secreted CCK and gastrin in culture media, does not lend support to the hypothesis that concomitant gene-expression of CCK receptors and gastrin or CCK are essential to maintaining pancreatic cancer cell proliferation.
Monstein
H J
HJ
Molecular Biology Laboratory, University Hospital, Linköping, Sweden.
Ohlsson
B
B
Axelson
J
J
D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology*; D002288:Adenocarcinoma, Mucinous / Q000235:genetics* / Q000473:pathology*; D000368:Aged; D001706:Biopsy; D015139:Blotting, Southern; D018270:Carcinoma, Ductal, Breast / Q000235:genetics* / Q000473:pathology*; D002291:Carcinoma, Papillary / Q000235:genetics* / Q000473:pathology*; D002455:Cell Division; D002766:Cholecystokinin / Q000032:analysis / Q000037:antagonists & inhibitors / Q000145:classification / Q000235:genetics*; D005755:Gastrins / Q000032:analysis / Q000037:antagonists & inhibitors / Q000502:physiology*; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D009367:Neoplasm Staging; D010190:Pancreatic Neoplasms / Q000235:genetics* / Q000473:pathology*; D012333:RNA, Messenger / Q000032:analysis / Q000502:physiology*; D011863:Radioimmunoassay; D011949:Receptors, Cholecystokinin / Q000032:analysis / Q000037:antagonists & inhibitors / Q000145:classification / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
D005755:Gastrins; D012333:RNA, Messenger; D011949:Receptors, Cholecystokinin; D002766:Cholecystokinin