Coexpression of gastrin and gastrin receptors (CCK-B and delta CCK-B) in gastrointestinal tumour cell lines.
BACKGROUND
The peptide hormone gastrin is a recognised growth factor for gastrointestinal (GI) tumour cells. Carboxyamidated gastrins bind to the cell surface gastrin/cholecystokinin B (CCK-B) receptor which can be expressed as either a normal or a truncated isoform (delta CCK-B).


OBJECTIVE
To compare gastrin gene expression with delta CCK-B and total CCK-B (both isoforms) gene expression in both GI and non-GI tract derived human tumour cell lines.


METHODS
Total RNA was extracted and gene expression was assayed by the reverse transcription-polymerase chain reaction followed by Southern blotting and hybridisation with specific oligo probes.


RESULTS
Gastrin was expressed by 5/5 gastric and 7/8 colorectal cell lines. Coexpression of gastrin CCK-B isoform was found in 80% of gastric and 75% of colorectal cell lines. Non-GI cell lines, with the exception of a lymphoblastic leukaemia cell line, showed no coexpression. The truncated receptor, delta CCK-B, was shown in 3/5 gastric and 5/8 colorectal cell lines and was always coexpressed with gastrin.


CONCLUSIONS
The truncated gastrin receptor, delta CCK-B, is coexpressed with gastrin in 8/13 GI tumour cell lines. Gastrin and CCK-B receptor isoforms may be involved in maintaining autocrine/paracrine growth pathways in GI cancer cells.
McWilliams
D F
DF
Department of Surgery, University Hospital, Nottingham, UK.
Watson
S A
SA
Crosbee
D M
DM
Michaeli
D
D
Seth
R
R
D015139:Blotting, Southern; D015179:Colorectal Neoplasms / Q000378:metabolism; D005755:Gastrins / Q000235:genetics* / Q000378:metabolism; D005770:Gastrointestinal Neoplasms / Q000378:metabolism*; D006801:Humans; D007536:Isomerism; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D043887:Receptor, Cholecystokinin B; D011949:Receptors, Cholecystokinin / Q000235:genetics* / Q000378:metabolism; D013274:Stomach Neoplasms / Q000378:metabolism; D014407:Tumor Cells, Cultured
D005755:Gastrins; D012333:RNA, Messenger; D043887:Receptor, Cholecystokinin B; D011949:Receptors, Cholecystokinin