title: Inhibition of mitogen-elicited signal transduction and growth in prostate cancer with a small peptide derived from the functional domain of DOC-2/DAB2 delivered by a unique vehicle.
abstract: Differentially expressed in ovarian cancer-2/disabled 2 (DOC-2/DAB2) protein, often lost in prostate cancer and other cancer types, is a part of homeostatic machinery in normal prostate epithelium. DOC-2/DAB2 modulates mitogen-elicited mitogen-activated protein kinase (MAPK) signal transduction by sequestering several adaptor or effector molecules, such as growth factor receptor bound protein 2 and c-Src. We have shown that the proline-rich sequence in DOC-2/DAB2 is the key functional domain for this action. In this study, we further synthesized peptide based on the functional proline-rich domain and examined its biological function in prostate cancer using cell-permeable peptide (CPP) as a delivery system. From screening of several CPPs in prostate cancer cell lines, a polyarginine peptide (R11) seemed to be the best delivery vehicle because of its highly efficient uptake. In addition, we also observed a similar in vitro half-life and cellular location of R11 in four different prostate cancer cell lines. By conjugating a proline-rich sequence (PPL) or control sequence (AAL) derived from DOC-2/DAB2 to the COOH terminus of R11, we showed that R11PPL but not R11 or R11AAL was able to suppress either serum- or androgen-induced cell proliferation in prostate cancer cells without endogenous DOC-2/DAB2 expression. Consistently, the activation status of MAPK elicited by these mitogens was significantly inhibited by R11PPL but not by R11AAL or R11. Taken together, we conclude that a functional peptide derived from proline-rich domain in DOC-2/DAB2 has growth-inhibitory activity as its native protein, and CPP seems to be an efficient delivery system in prostate cancer cells.
authors.affiliation: Department of Urology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9110, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhou
authors.forename: Jinhai
authors.initials: J
authors.lastname: Fan
authors.forename: Jer-Tsong
authors.initials: JT
authors.lastname: Hsieh
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D000595:Amino Acid Sequence; D051017:Apoptosis Regulatory Proteins; D048708:Cell Growth Processes / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology; D015195:Drug Design; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D008297:Male; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D010446:Peptide Fragments / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D017434:Protein Structure, Tertiary; D025521:Tumor Suppressor Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; C102885:DAB2 protein, human; D009842:Oligopeptides; D010446:Peptide Fragments; C568793:R11 peptide; D025521:Tumor Suppressor Proteins