Document Detail

Molecular and functional studies of inhibitory G protein in RINm5F cells.
MedLine Citation:
PMID:  7526047     Owner:  NLM     Status:  MEDLINE    
Inhibitory G proteins (Gi) play an important role in cell proliferation. In order to characterize Gi proteins in RINm5F (RIN) cells, we first established RIN cells in cell culture. Immunoblot analysis was performed on extracted G proteins using Western blot techniques and a Gi-specific antibody. We identified three prominent bands consistent with three distinct inhibitory alpha subunits of membrane-bound G protein (Gi) in RIN cells. In contrast, we identified only one prominent distinct inhibitory alpha subunit of G protein in an equal quantity of membrane-protein in our control (normal rat pancreas). In several cell types, Gi is known to mediate the inhibitory action of somatostatin on intracellular cyclic AMP (cAMP) accumulation. Therefore, we studied the action of the long-acting analogue of somatostatin, octreotide (SMS), on basal and 3-isobutyl-1-methylxanthine-stimulated cAMP accumulation in RIN cells. SMS did not inhibit cAMP accumulation or tritiated thymidine incorporation into DNA (TTID) in RIN cells. However, when treatment with SMS is supplemented with the nonhydrolyzable analogue of guanine nucleotide, Gpp(NH)p (Gpp), which is known to dissociate G proteins into its constitutive subunits, then SMS+Gpp induced an inhibitory action and significantly reduced cAMP accumulation and TTID. These data are consistent with the concept of qualitatively and functionally altered inhibitory G protein expression in the insulin-producing, islet cell (RINm5F) rat insulinoma tumor cell line. Further study of human tumors will lead to new insights into the clinical implications of G protein-mediated signal transduction in insulinoma.
M K McLeod; P C Kothary; C M Farrell
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of surgical research     Volume:  57     ISSN:  0022-4804     ISO Abbreviation:  J. Surg. Res.     Publication Date:  1994 Nov 
Date Detail:
Created Date:  1994-12-08     Completed Date:  1994-12-08     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  0376340     Medline TA:  J Surg Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  619-24     Citation Subset:  IM    
Department of Surgery, University of Michigan Medical Center, Ann Arbor 48109.
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MeSH Terms
1-Methyl-3-isobutylxanthine / pharmacology
Cyclic AMP / metabolism
DNA, Neoplasm / biosynthesis
Drug Combinations
GTP-Binding Proteins / metabolism*
Guanylyl Imidodiphosphate / pharmacology
Insulinoma / drug therapy,  metabolism*
Octreotide / pharmacology
Pancreas / metabolism
Pancreatic Neoplasms / drug therapy,  metabolism*
Tumor Cells, Cultured
Reg. No./Substance:
0/DNA, Neoplasm; 0/Drug Combinations; 28822-58-4/1-Methyl-3-isobutylxanthine; 34273-04-6/Guanylyl Imidodiphosphate; 60-92-4/Cyclic AMP; 83150-76-9/Octreotide; EC 3.6.1.-/GTP-Binding Proteins

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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