title: Hyaluronan-binding peptide can inhibit tumor growth by interacting with Bcl-2.
abstract: Previous studies have indicated that proteins that bind hyaluronan can also inhibit the growth of tumor cells. To determine if synthetic peptides also possessed these properties, we tested a series of polypeptides containing structural motifs from different proteins for their ability to bind [(3)H]hyaluronan, and identified one compound termed P4 that had a particularly strong interaction. Further studies revealed that P4 also inhibited the growth of tumor cells in tissue culture as well as on the chorioallantoic membranes of chicken embryos. In addition, expression vectors for P4 caused tumor cells to grow slower in nude mice and reduced their vascularization. The P4 peptide also inhibited VEGF-induced angiogenesis in the chorioallantoic membranes of chicken embryos. Studies on cultured cells indicated that P4 induced apoptosis, which was blocked by a pan-caspase inhibitor. Confocal microscopy revealed that shortly after its uptake, P4 became associated with mitochondria. Immunoprecipitation indicated that P4 could bind to Bcl-2 and Bcl-x(L), which are associated with mitochondria and regulate apoptosis. This was also supported by the fact that P4 induced the release of cytochrome c from preparations of mitochondria. Taken together, these results suggest that P4 binds to Bcl-2 and related proteins and this activates the apoptotic cascade.
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington DC, USA.
authors.forename: Ninfei
authors.initials: N
authors.lastname: Liu
authors.forename: Xue-Ming
authors.initials: XM
authors.lastname: Xu
authors.forename: Jinguo
authors.initials: J
authors.lastname: Chen
authors.forename: Luping
authors.initials: L
authors.lastname: Wang
authors.forename: Shanmin
authors.initials: S
authors.lastname: Yang
authors.forename: Charles B
authors.initials: CB
authors.lastname: Underhill
authors.forename: Lurong
authors.initials: L
authors.lastname: Zhang
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D019556:COS Cells; D002455:Cell Division; D002460:Cell Line; D045744:Cell Line, Tumor; D002642:Chick Embryo; D046508:Culture Techniques; D045304:Cytochromes c / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D005822:Genetic Vectors; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism / Q000502:physiology*; D006820:Hyaluronic Acid / Q000737:chemistry; D051379:Mice; D008819:Mice, Nude; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000378:metabolism; D041681:NIH 3T3 Cells; D009369:Neoplasms / Q000378:metabolism*; D009389:Neovascularization, Pathologic; D010455:Peptides / Q000737:chemistry; D011233:Precipitin Tests; D011485:Protein Binding; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D014162:Transfection; D051020:bcl-X Protein
chemical_list: C494811:BCL2L1 protein, human; C494812:Bcl2l1 protein, mouse; D004791:Enzyme Inhibitors; D018960:Hyaluronan Receptors; D010455:Peptides; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein; D006820:Hyaluronic Acid; D045304:Cytochromes c