10084601

pubmed:Citation

3

The protein product of the novH oncogene, a member of the CCN family, is structurally related to the insulin-like growth factor (IGF) binding proteins (IGFBPs). We have characterized aspects of structure, function, and distribution of this protein, which, as IGFBP-related protein 3 (IGFBP-rP3), is a proposed member of the IGFBP Superfamily. Affinity cross-linking experiments performed with baculovirus synthesized recombinant human IGFBP-rP3 established that rhIGFBP-rP3 binds IGF-I, IGF-II, and insulin with low affinity. Specificity of binding was shown by competitive cross-linking experiments; binding to IGF-I and -II was also demonstrated by nondenaturing Western ligand blots. Northern blot analysis indicated the presence of IGFBP-rP3 messenger RNA (mRNA) in a broad range of human tissues. Western immunoblotting studies, using a polyclonal rabbit anti-rhIGFBP-rP3 antibody, demonstrated that IGFBP-rP3 protein is synthesized in vitro by several breast and prostate cancer cell lines: Hs578T, PC3, P69, and LNCaP cells. Western immunoblotting studies of human biological fluids identified that IGFBP-rP3 was present in normal serum, pregnancy serum, serum from patients with growth hormone receptor deficiency, cerebrospinal fluid, amniotic fluid, peritoneal fluid, and follicular fluid, while IGFBP-rP3 fragments were identified in cerebrospinal fluid, amniotic fluid, and prepubertal and pubertal urine samples. Our studies demonstrate that IGFBP-rP3 exhibits IGF binding, albeit at low affinity, and IGFBP-rP3 thus merits inclusion in the IGFBP Superfamily. The low affinity IGF binding suggests that IGFBP-rP3 may act primarily independently of the IGFs. The synthesis of IGFBP-rP3 by several malignant cell lines and its presence in human biological fluids suggest that this protein possesses other interesting roles, potentially in cell growth regulation.

eng

AIM

MEDLINE

0021-972X

Print

NLM

1096-103

pubmed-meshheading:10084601-Amino Acid Sequence, pubmed-meshheading:10084601-Animals, pubmed-meshheading:10084601-Antibodies, pubmed-meshheading:10084601-Cell Line, pubmed-meshheading:10084601-Connective Tissue Growth Factor, pubmed-meshheading:10084601-Epitopes, pubmed-meshheading:10084601-Female, pubmed-meshheading:10084601-Growth Substances, pubmed-meshheading:10084601-Humans, pubmed-meshheading:10084601-Immediate-Early Proteins, pubmed-meshheading:10084601-Insulin-Like Growth Factor Binding Protein 3, pubmed-meshheading:10084601-Intercellular Signaling Peptides and Proteins, pubmed-meshheading:10084601-Molecular Sequence Data, pubmed-meshheading:10084601-Nephroblastoma Overexpressed Protein, pubmed-meshheading:10084601-Peptides, pubmed-meshheading:10084601-Pregnancy, pubmed-meshheading:10084601-RNA, Messenger, pubmed-meshheading:10084601-Rabbits, pubmed-meshheading:10084601-Recombinant Proteins, pubmed-meshheading:10084601-Sequence Tagged Sites, pubmed-meshheading:10084601-Tissue Distribution

Binding properties and distribution of insulin-like growth factor binding protein-related protein 3 (IGFBP-rP3/NovH), an additional member of the IGFBP Superfamily.

Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.