title: Biological activity of rainbow trout Ea4-peptide of the pro-insulin-like growth factor (pro-IGF)-I on promoting attachment of breast cancer cells (MDA-MB-231) via alpha2- and beta1-integrin.
abstract: E-peptide of pro-IGF-I was considered as biologically inactive. We have demonstrated that rainbow trout (rt) Ea4-peptide exerted biological activities in several established tumor cell lines [Chen et al., 2002; Kuo and Chen, 2002]. Here we report the activity of rtEa4-peptide in promoting attachment of human breast cancer cells (MDA-MB-231). While rtEa2-, rtEa3-, and rtEa4-peptides enhanced the attachment of MDA-MB-231 cells in a dose dependent manner, rtEa4-peptide possessed the highest activity. Antibodies specific to alpha2 and beta1 integrins significantly inhibited the attachment of cells to rtEa4-peptide coated-plates by 40%. In addition, rtEa4-peptide induced the expression of fibronectin 1 and laminin receptor genes in MDA-MB-231 cells. Blocking new protein synthesis by cycloheximide significantly reduced the attachment of MDA-MB-231 cells to rtEa4-peptide coated wells by 50%. These results suggest that rtEa4-peptide may promote cell attachment by interacting with alpha2/beta1 integrin receptors at the cell surface and by inducing the expression of fibronectin 1 and laminin receptor genes. Expression of fibronectin 1 gene induced by rtEa4-peptide in MDA-MB-231 cells was abolished by inhibitors of PI3K, PKC, Mek1/2, JNK1/2, and p38 MAPK signaling transduction molecules. These results suggested that induction of fibronectin 1 gene expression in MDA-MB-231 cells by rtEa4-peptide may be mediated via PI3K, PKC, Mek1/2, JNK1/2, and p38 MAPK signal transduction molecules.
authors.affiliation: Department of Molecular and Cell Biology, University of Connecticut, 91 North Eagleville Road, Storrs, CT 06269, USA.
authors.forename: Sineenat
authors.initials: S
authors.lastname: Siri
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Chen
authors.forename: Thomas T
authors.initials: TT
authors.lastname: Chen
mesh_terms: D000818:Animals; D001483:Base Sequence; D001943:Breast Neoplasms / Q000473:pathology*; D045744:Cell Line, Tumor; D017931:DNA Primers; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D039421:Integrin alpha2 / Q000502:physiology*; D039081:Integrin alpha5beta1 / Q000235:genetics; D019012:Integrin beta1 / Q000502:physiology*; D017686:Oncorhynchus mykiss; D017474:Receptors, Laminin / Q000235:genetics; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D017931:DNA Primers; D039421:Integrin alpha2; D039081:Integrin alpha5beta1; D019012:Integrin beta1; D017474:Receptors, Laminin; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I