Identification of a novel insulin-like growth factor binding protein gene homologue with tumor suppressor like properties.
Here we report the identification of a new insulin-like growth factor binding protein homologue, provisionally designated insulin-like growth factor binding related protein-4 (IGFBP-rP4). IGFBP-rP4 was found to be most closely related to IGFBP-7 with 52% amino acid homology and 43% amino acid identity, and shares a similar domain structure. Semi-quantitative RT-PCR expression analysis demonstrated a pattern of downregulation of this gene in multiple tumor samples including lung and colon cancer, compared to matched adjacent normal tissue. Western blotting revealed a protein of approximately 38kDa expressed in both the cell pellet and secreted into the supernatant of transiently transfected Cos-7 cells. Cos-7 supernatants containing IGFBP-RP4 protein were observed to suppress the growth of HeLa cells in culture compared to vector controls. IGFBP-RP4 directly transiently transfected into HeLa cells also further confirmed the growth suppressive properties of this protein. Together these data suggest that IGFBP-RP4 may be a novel putative tumor suppressor protein.
Cai
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Nuvelo, Inc., 675 Almanor Ave., Sunnyvale, CA 94085, USA.
Chen
H T
HT
Boyle
B
B
Rupp
F
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Funk
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Dedera
D A
DA
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D006367:HeLa Cells; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins / Q000145:classification / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*
C501532:IGFBPL1 protein, human; D018969:Insulin-Like Growth Factor Binding Proteins; D025521:Tumor Suppressor Proteins