title: Csk homologous kinase associates with RAFTK/Pyk2 in breast cancer cells and negatively regulates its activation and breast cancer cell migration.
abstract: Our recent observations indicated that RAFTK (also termed Pyk2 and CAK-beta) participated in intracellular signaling upon heregulin (HRG) stimulation and promoted breast carcinoma invasion. Furthermore, studies from our group indicate that the Csk homologous kinase (CHK), a member of the Csk family, directly associates with HER2/Neu and down-regulates HER2/Neu-mediated Src kinase activation in breast cancer cells upon heregulin stimulation. Since activation of RAFTK is associated with the activity of Src family kinases, we analyzed whether CHK is capable of opposing HRG-induced activation of RAFTK. Stimulation of human T47D breast cancer cells with HRG induced the tyrosine phosphorylation of RAFTK and its association with CHK in vitro and in vivo. This interaction was mediated through the Src binding site (amino acid residue at 402) of RAFTK and the SH2 domain of CHK. RAFTK phosphorylation downstream of the activated HER2/Neu was greatly reduced in the presence of CHK. Maximal inhibition of RAFTK phosphorylation by CHK required the kinase activity of CHK. Furthermore, CHK inhibited the tyrosine phosphorylation of the focal adhesion-associated protein, paxillin, and inhibited HRG-induced T47D breast cancer cell migration. These findings indicate the role of CHK as a negative regulator in HRG- and RAFTK-mediated intracellular signaling in breast cancer cells.
authors.affiliation: Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Harvard Institutes of Medicine, Boston, MA 02115, USA.
authors.forename: Gina D
authors.initials: GD
authors.lastname: McShan
authors.forename: Radoslaw
authors.initials: R
authors.lastname: Zagozdzon
authors.forename: Shin-Young
authors.initials: SY
authors.lastname: Park
authors.forename: Sheila
authors.initials: S
authors.lastname: Zrihan-Licht
authors.forename: Yigong
authors.initials: Y
authors.lastname: Fu
authors.forename: Shalom
authors.initials: S
authors.lastname: Avraham
authors.forename: Hava
authors.initials: H
authors.lastname: Avraham
mesh_terms: D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D000081247:CSK Tyrosine-Protein Kinase; D002465:Cell Movement / Q000187:drug effects; D003598:Cytoskeletal Proteins / Q000378:metabolism; D015536:Down-Regulation / Q000502:physiology; D005260:Female; D051418:Focal Adhesion Kinase 2; D022001:Focal Adhesions; D006801:Humans; D008533:Megakaryocytes; D009361:Neoplasm Invasiveness; D020890:Neuregulin-1 / Q000494:pharmacology*; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D010957:Plasmids; D011233:Precipitin Tests; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src); D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases
chemical_list: D000081247:CSK Tyrosine-Protein Kinase; D003598:Cytoskeletal Proteins; D051418:Focal Adhesion Kinase 2; D020890:Neuregulin-1; D051419:Paxillin; D010750:Phosphoproteins; D011505:Protein-Tyrosine Kinases; D016392:Proto-Oncogene Proteins pp60(c-src); D018719:Erb-b2 Receptor Tyrosine Kinases; D011994:Recombinant Proteins; D014443:Tyrosine; D019061:src-Family Kinases; C496061:PXN protein, human; C085377:MATK protein, human; C000631346:CSK protein, human