title: Modulation of RhoA GTPase Activity Sensitizes Human Cervix Carcinoma Cells to γ-Radiation by Attenuating DNA Repair Pathways.
abstract: Radiotherapy with γ-radiation is widely used in cancer treatment to induce DNA damage reducing cell proliferation and to kill tumor cells. Although RhoA GTPase overexpression/hyperactivation is observed in many malignancies, the effect of RhoA activity modulation on cancer radiosensitivity has not been previously investigated. Here, we generated stable HeLa cell clones expressing either the dominant negative RhoA-N19 or the constitutively active RhoA-V14 and compared the responses of these cell lines with those of parental HeLa cells, after treatment with low doses of γ-radiation. HeLa-RhoA-N19 and HeLa-RhoA-V14 clones displayed reduced proliferation and survival compared to parental cells after radiation and became arrested at cell cycle stages correlated with increased cellular senescence and apoptosis. Also, Chk1/Chk2 and histone H2A phosphorylation data, as well as comet assays, suggest that the levels of DNA damage and DNA repair activation and efficiency in HeLa cell lines are correlated with active RhoA. In agreement with these results, RhoA inhibition by C3 toxin expression drastically affected homologous recombination (HR) and nonhomologous end joining (NHEJ). These data suggest that modulation of RhoA GTPase activity impairs DNA damage repair, increasing HeLa cell radiosensitivity.
authors.affiliation: Laboratory of Signaling in Biomolecular Systems, Department of Biochemistry, Institute of Chemistry, University of São Paulo, 05508-000 São Paulo, SP, Brazil.
authors.forename: Juliana H
authors.initials: JH
authors.lastname: Osaki
authors.affiliation: Laboratory of Signaling in Biomolecular Systems, Department of Biochemistry, Institute of Chemistry, University of São Paulo, 05508-000 São Paulo, SP, Brazil.
authors.forename: Gisele
authors.initials: G
authors.lastname: Espinha
authors.affiliation: Laboratory of Signaling in Biomolecular Systems, Department of Biochemistry, Institute of Chemistry, University of São Paulo, 05508-000 São Paulo, SP, Brazil.
authors.forename: Yuli T
authors.initials: YT
authors.lastname: Magalhaes
authors.affiliation: Laboratory of Signaling in Biomolecular Systems, Department of Biochemistry, Institute of Chemistry, University of São Paulo, 05508-000 São Paulo, SP, Brazil.
authors.forename: Fabio L
authors.initials: FL
authors.lastname: Forti
mesh_terms: D036002:ADP Ribose Transferases / Q000494:pharmacology; D001905:Botulinum Toxins / Q000494:pharmacology; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2 / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects*; D005260:Female; D005720:Gamma Rays; D006367:HeLa Cells; D006801:Humans; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D002583:Uterine Cervical Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D009363:Neoplasm Proteins; C066737:RHOA protein, human; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; C000605867:CHEK1 protein, human; C578634:CHEK2 protein, human; D000071877:Checkpoint Kinase 1; D001905:Botulinum Toxins; D020742:rhoA GTP-Binding Protein