期刊
ONCOGENE
卷 26, 期 3, 页码 425-440出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/sj.onc.1209798
关键词
Mr of gastrin-binding proteins; SELDI-TOFMS; antisense and sense Annexin II RNA
资金
- NATIONAL CANCER INSTITUTE [R01CA097959, R01CA072992] Funding Source: NIH RePORTER
- NCI NIH HHS [CA72992, CA097959, R01 CA097959] Funding Source: Medline
We and others have reported the presence of novel progastrin (PG)/gastrin receptors on normal and cancerous intestinal cells. We had earlier reported the presence of 33 - 36 kDa gastrin-binding proteins on cellular membranes of colon cancer cells. The goal of the current study was to identify the protein(s) in the 33 - 36 kDa band, and analyse its functional significance. A carbodiimide crosslinker was used for crosslinking radio-labeled gastrins to membrane proteins from gastrin/PG responsive cell lines. Native membrane proteins, crosslinked to the ligand, were solubulized and enriched by > 1000-fold, and analysed by surface-enhanced laser desorption/ionization-time of light-mass spectrometry. The peptide masses were researched against the NCBInr database using the ProFound search engine. Annexin II (ANX II) was identified, and confirmed by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry. As HCT-116 cells express autocrine PG, the in situ association of PG with ANX II was demonstrated in pulldown assays. Direct binding of PG with ANX II was confirmed in an in vitro binding assay. In order to confirm a functional importance of these observations, sense and anti-sense (AS) ANX II RNA-expressing clones of intestinal epithelial (IEC-18) and human colon cancer (HCT-116) cell lines were generated. AS clones demonstrated a significant loss in the growth response to exogenous (IEC-18) and autocrine (HCT-116) PG. We have thus discovered that membrane-associated ANX II binds PG/gastrins, and partially mediates growth factor effects of the peptides.
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