title: StarD13 is a tumor suppressor in breast cancer that regulates cell motility and invasion.
abstract: Breast cancer is one of the most commonly diagnosed cancers in women around the world. In general, the more aggressive the tumor, the more rapidly it grows and the more likely it metastasizes. Members of the Rho subfamily of small GTP-binding proteins (GTPases) play a central role in breast cancer cell motility and metastasis. The switch between active GTP-bound and inactive GDP-bound state is regulated by guanine nucleotide exchange factors (GEFs), GTPase-activating proteins (GAPs) and guanine-nucleotide dissociation inhibitors (GDIs). We studied the role of StarD13, a recently identified Rho-GAP that specifically inhibits the function of RhoA and Cdc42. We aimed to investigate its role in breast cancer proliferation and metastasis. The levels of expression of this Rho-GAP in tumor tissues of different grades were assayed using immunohistochemistry. We observed that, while the level of StarD13 expression decreases in cancer tissues compared to normal tissues, it increases as the grade of the tumor increased. This was consistent with the fact that although StarD13 was indeed a tumor suppressor in our breast cancer cells, as seen by its effect on cell proliferation, it was needed for cancer cell motility. In fact, StarD13 knockdown resulted in an inhibition of cell motility and cells were not able to detach their tail and move forward. Our study describes, for the first time, a tumor suppressor that plays a positive role in cancer motility.
authors.affiliation: Department of Natural Sciences, The Lebanese American University, Beirut 1102 2801, Lebanon.
authors.forename: Samer
authors.initials: S
authors.lastname: Hanna
authors.affiliation: Department of Natural Sciences, The Lebanese American University, Beirut 1102 2801, Lebanon.
authors.forename: Bassem
authors.initials: B
authors.lastname: Khalil
authors.affiliation: Department of Natural Sciences, The Lebanese American University, Beirut 1102 2801, Lebanon.
authors.forename: Anita
authors.initials: A
authors.lastname: Nasrallah
authors.affiliation: Department of Natural Sciences, The Lebanese American University, Beirut 1102 2801, Lebanon.
authors.forename: Bechara A
authors.initials: BA
authors.lastname: Saykali
authors.affiliation: School of Medicine, The Lebanese American University, Beirut 1102 2801, Lebanon.
authors.forename: Rania
authors.initials: R
authors.lastname: Sobh
authors.affiliation: School of Medicine, The Lebanese American University, Beirut 1102 2801, Lebanon.
authors.forename: Selim
authors.initials: S
authors.lastname: Nasser
authors.affiliation: Department of Natural Sciences, The Lebanese American University, Beirut 1102 2801, Lebanon.
authors.forename: Mirvat
authors.initials: M
authors.lastname: El-Sibai
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D002448:Cell Adhesion; D002453:Cell Cycle; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D005260:Female; D020690:GTPase-Activating Proteins; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D006801:Humans; D061986:MCF-7 Cells; D009361:Neoplasm Invasiveness / Q000473:pathology*; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism*; D020744:rac GTP-Binding Proteins / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: D020690:GTPase-Activating Proteins; C473607:STARD13 protein, human; D025521:Tumor Suppressor Proteins; C066737:RHOA protein, human; D020744:rac GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein