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Identification of a novel insulin-like growth factor binding protein gene homologue with tumor suppressor like properties

2005; Elsevier BV; Volume: 331; Issue: 1 Linguagem: Inglês

10.1016/j.bbrc.2005.03.163

1090-2104

Zheng Cai, H.T. Chen, B. Boyle, Fabio Rupp, Walter D. Funk, Douglas A. Dedera,

Metabolism, Diabetes, and Cancer

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 38 kDa 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.