Identification of a novel insulin-like growth factor binding protein gene homologue with tumor suppressor like properties
Section snippets
Materials and methods
Cell lines and tissues. All cell lines used in this study were obtained from the American Type Culture Collection (ATCC) and included the Cos-7 (an African Green Monkey kidney cell line) and HeLa cells (human cervical carcinoma cells). Culturing of cell lines was performed using standard protocols. All healthy tissue total RNAs were obtained from either Ambion or Clontech. Cancer patient tissues were obtained from the Cooperative Human Tissue Network (CHTN) or from Clontech and Ambion where
IGFBP-RP4 gene characterization
The IGFBP-RP4 cDNA and protein sequences are shown in Fig. 1. IGFBP-RP4 is a protein of 278 amino acids with a signal peptide and conserved motifs found in the IGFBP family of proteins. The signal peptide runs from the N-terminus through G27, which is where the signal peptide cleavage site is predicted. Additionally, from amino acid D61 through S76, there is a conserved IGFBP family signature as predicted by the eMatrix software program. The Pfam software program predicts a Kazal
Discussion
A number of IGFBP family members have been suggested to have tumor suppressor like properties. IGFBP-3 has been shown to suppress the growth of breast cancer cells and the prostate cancer cell line PC-3 [1]. IGFBP-7, the family member that shares the greatest sequence similarity to IGFBP-rP4, had been demonstrated to suppress the growth of HeLa, P19 (murine embryonic carcinoma cells), and Saos-2 (osteosarcoma cells) when recombinant IGFBP-7 protein was added to the culture medium [11].
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