title: Identification of H-Ras-specific motif for the activation of invasive signaling program in human breast epithelial cells.
abstract: Increased expression and/or activation of H-Ras are often associated with tumor aggressiveness in breast cancer. Previously, we showed that H-Ras, but not N-Ras, induces MCF10A human breast epithelial cell invasion and migration, whereas both H-Ras and N-Ras induce cell proliferation and phenotypic transformation. In an attempt to determine the sequence requirement directing the divergent phenotype induced by H-Ras and N-Ras with a focus on the induction of human breast cell invasion, we investigated the structural and functional relationships between H-Ras and N-Ras using domain-swap and site-directed mutagenesis approaches. Here, we report that the hypervariable region (HVR), consisting of amino acids 166 to 189 in H-Ras, determines the invasive/migratory signaling program as shown by the exchange of invasive phenotype by swapping HVR sequences between H-Ras and N-Ras. We also demonstrate that the H-Ras-specific additional palmitoylation site at Cys184 is not responsible for the signaling events that distinguish between H-Ras and N-Ras. Importantly, this work identifies the C-terminal HVR, especially the flexible linker domain with two consecutive proline residues Pro173 and Pro174, as a critical domain that contributes to activation of H-Ras and its invasive potential in human breast epithelial cells. The present study sheds light on the structural basis for the Ras isoform-specific invasive program of breast epithelial cells, providing information for the development of agents that specifically target invasion-related H-Ras pathways in human cancer.
authors.affiliation: College of Pharmacy, Duksung Women's University, Seoul, South Korea.
authors.forename: Hae-Young
authors.initials: HY
authors.lastname: Yong
authors.forename: Jin-Sun
authors.initials: JS
authors.lastname: Hwang
authors.forename: Hwajin
authors.initials: H
authors.lastname: Son
authors.forename: Hae-In
authors.initials: HI
authors.lastname: Park
authors.forename: Eok-Soo
authors.initials: ES
authors.lastname: Oh
authors.forename: Hyun-Hwi
authors.initials: HH
authors.lastname: Kim
authors.forename: Do Kyun
authors.initials: DK
authors.lastname: Kim
authors.forename: Wahn Soo
authors.initials: WS
authors.lastname: Choi
authors.forename: Bong-Jin
authors.initials: BJ
authors.lastname: Lee
authors.forename: Hyeong-Reh Choi
authors.initials: HR
authors.lastname: Kim
authors.forename: Aree
authors.initials: A
authors.lastname: Moon
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D004847:Epithelial Cells / Q000378:metabolism / Q000473:pathology; D005260:Female; D011905:Genes, ras; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009361:Neoplasm Invasiveness; D011392:Proline / Q000235:genetics / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013329:Structure-Activity Relationship
chemical_list: D011392:Proline; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)