title: Synuclein-gamma targeting peptide inhibitor that enhances sensitivity of breast cancer cells to antimicrotubule drugs.
abstract: Synuclein-gamma (SNCG) plays oncogenic roles in breast carcinogenesis. Although the expression of SNCG is abnormally high in advanced and metastatic breast carcinomas, SNCG is not expressed in normal or benign breast tissues. SNCG is an intrinsically disordered protein known to interact with BubR1, a mitotic checkpoint kinase. The SNCG-BubR1 interaction inhibits mitotic checkpoint control upon spindle damage caused by anticancer drugs, such as nocodazole and taxol. Antimicrotubule drugs that cause mitotic arrest and subsequent apoptosis of cancer cells are frequently used to treat breast cancer patients with advanced or metastatic diseases. However, patient response rates to this class of chemotherapeutic agents vary significantly. In this study, we have designed a novel peptide (ANK) and shown its interaction with SNCG using fluorometry, surface plasmon resonance, and isothermal titration calorimetry. Binding of the ANK peptide did not induce folding of SNCG, suggesting that SNCG can function biologically in its intrinsically disordered state. Microinjection of the ANK peptide in breast cancer cell line overexpressing SNCG (MCF7-SNCG) exhibited a similar cell killing response by nocodazole as in the SNCG-negative MCF7 cells. Overexpression of enhanced green fluorescent protein-tagged ANK reduces SNCG-mediated resistance to paclitaxel treatment by approximately 3.5-fold. Our coimmunoprecipitation and colocalization results confirmed the intracellular association of the ANK peptide with SNCG. This is likely due to the disruption of the interaction of SNCG with BubR1 interaction. Our findings shed light on the molecular mechanism of the ANK peptide in releasing SNCG-mediated drug resistance.
authors.affiliation: Department of Biochemistry, Queen's University, Kingston, Ontario, and Molecular Structure and Function, Hospital for Sick Children, Toronto, Canada.
authors.forename: Vinay K
authors.initials: VK
authors.lastname: Singh
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhou
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Marsh
authors.forename: Vladimir N
authors.initials: VN
authors.lastname: Uversky
authors.forename: Julie D
authors.initials: JD
authors.lastname: Forman-Kay
authors.forename: Jingwen
authors.initials: J
authors.lastname: Liu
authors.forename: Zongchao
authors.initials: Z
authors.lastname: Jia
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017487:Ankyrins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D019556:COS Cells; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D017124:Conserved Sequence; D019008:Drug Resistance, Neoplasm; D006801:Humans; D007700:Kinetics; D008870:Microtubules / Q000187:drug effects; D008938:Mitosis / Q000187:drug effects; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015739:Nocodazole / Q000494:pharmacology*; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D017510:Protein Folding; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D051845:gamma-Synuclein / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D017487:Ankyrins; D000970:Antineoplastic Agents; D009363:Neoplasm Proteins; D010446:Peptide Fragments; C104249:SNCG protein, human; D051845:gamma-Synuclein; D011494:Protein Kinases; C584277:BUB1 protein, human; C090464:Bub1 spindle checkpoint protein; D017346:Protein Serine-Threonine Kinases; D015739:Nocodazole