title: RAD50 targeting impairs DNA damage response and sensitizes human breast cancer cells to cisplatin therapy.
abstract: In tumor cells the effectiveness of anti-neoplastic agents that cause cell death by induction of DNA damage is influenced by DNA repair activity. RAD50 protein plays key roles in DNA double strand breaks repair (DSBs), which is crucial to safeguard genome integrity and sustain tumor suppression. However, its role as a potential therapeutic target has not been addressed in breast cancer. Our aim in the present study was to analyze the expression of RAD50 protein in breast tumors, and evaluate the effects of RAD50-targeted inhibition on the cytotoxicity exerted by cisplatin and anthracycline and taxane-based therapies in breast cancer cells. Immunohistochemistry assays on tissue microarrays indicate that the strong staining intensity of RAD50 was reduced in 14% of breast carcinomas in comparison with normal tissues. Remarkably, RAD50 silencing by RNA interference significantly enhanced the cytotoxicity of cisplatin. Combinations of cisplatin with doxorubicin and paclitaxel drugs induced synergistic effects in early cell death of RAD50-deficient MCF-7, SKBR3, and T47D breast cancer cells. Furthermore, we found an increase in the number of DSBs, and delayed phosphorylation of histone H2AX after cisplatin treatment in RAD50-silenced cells. These cellular events were associated to a dramatical increase in the frequency of chromosomal aberrations and a decrease of cell number in metaphase. In conclusion, our data showed that RAD50 abrogation impairs DNA damage response and sensitizes breast cancer cells to cisplatin-combined therapies. We propose that the development and use of inhibitors to manipulate RAD50 levels might represent a promising strategy to sensitize breast cancer cells to DNA damaging agents.
authors.affiliation: Oncogenomics and Cancer Proteomics Laboratory; Genomics Sciences Program; Autonomous University of Mexico City; Mexico DF, Mexico.
authors.forename: Ali
authors.initials: A
authors.lastname: Flores-Pérez
authors.affiliation: Oncogenomics and Cancer Proteomics Laboratory; Genomics Sciences Program; Autonomous University of Mexico City; Mexico DF, Mexico.
authors.forename: Lourdes E
authors.initials: LE
authors.lastname: Rafaelli
authors.affiliation: Oncogenomics and Cancer Proteomics Laboratory; Genomics Sciences Program; Autonomous University of Mexico City; Mexico DF, Mexico.
authors.forename: Nayeli
authors.initials: N
authors.lastname: Ramírez-Torres
authors.affiliation: Virus and Cancer Laboratory; National Institute of Cancerology; Mexico DF, Mexico.
authors.forename: Elena
authors.initials: E
authors.lastname: Aréchaga-Ocampo
authors.affiliation: Oncogenomics and Cancer Proteomics Laboratory; Genomics Sciences Program; Autonomous University of Mexico City; Mexico DF, Mexico; National Institute of Pediatrics; Biomedical Research Institute; National Autonomous University of Mexico; Mexico DF, Mexico.
authors.forename: Sara
authors.initials: S
authors.lastname: Frías
authors.affiliation: National Institute of Pediatrics; Biomedical Research Institute; National Autonomous University of Mexico; Mexico DF, Mexico.
authors.forename: Silvia
authors.initials: S
authors.lastname: Sánchez
authors.affiliation: Molecular Biomedicine Program and Biotechnology Network; National School of Medicine and Homeopathy; National Polytechnic Institute; Mexico DF, Mexico.
authors.forename: Laurence A
authors.initials: LA
authors.lastname: Marchat
authors.affiliation: Cancer Genomics Laboratory; National Institute of Genomic Medicine; Mexico DF, Mexico.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Hidalgo-Miranda
authors.affiliation: Cancer Genomics Laboratory; National Institute of Genomic Medicine; Mexico DF, Mexico.
authors.forename: Valeria
authors.initials: V
authors.lastname: Quintanar-Jurado
authors.affiliation: Institute of Breast Diseases; FUCAM; Mexico DF, Mexico.
authors.forename: Sergio
authors.initials: S
authors.lastname: Rodríguez-Cuevas
authors.affiliation: Institute of Breast Diseases; FUCAM; Mexico DF, Mexico.
authors.forename: Verónica
authors.initials: V
authors.lastname: Bautista-Piña
authors.affiliation: Lung Cancer Laboratory; National Institute of Respiratory Diseases; Mexico DF, Mexico.
authors.forename: Angeles
authors.initials: A
authors.lastname: Carlos-Reyes
authors.affiliation: Oncogenomics and Cancer Proteomics Laboratory; Genomics Sciences Program; Autonomous University of Mexico City; Mexico DF, Mexico.
authors.forename: César
authors.initials: C
authors.lastname: López-Camarillo
mesh_terms: D017766:Acid Anhydride Hydrolases; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000201:enzymology*; D018270:Carcinoma, Ductal, Breast / Q000201:enzymology*; D002945:Cisplatin / Q000494:pharmacology*; D004249:DNA Damage; D045643:DNA Repair Enzymes / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D055785:Gene Knockdown Techniques; D006657:Histones / Q000378:metabolism; D006801:Humans; D061986:MCF-7 Cells; D011499:Protein Processing, Post-Translational; D034741:RNA, Small Interfering / Q000235:genetics; D046888:Tissue Array Analysis
chemical_list: D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; C468783:H2AX protein, human; D006657:Histones; D034741:RNA, Small Interfering; D017766:Acid Anhydride Hydrolases; C112158:RAD50 protein, human; D045643:DNA Repair Enzymes; D002945:Cisplatin
keywords: DNA damage; RAD50 targeting; breast cancer; chemosensitization; chromosomal aberrations; cisplatin; doxorubicin; histone H2AX; paclitaxel