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Cancer Biol Ther. 2014 Jun 1;15(6):777-88. doi: 10.4161/cbt.28551. Epub 2014 Mar 18.

RAD50 targeting impairs DNA damage response and sensitizes human breast cancer cells to cisplatin therapy.

Author information

1
Oncogenomics and Cancer Proteomics Laboratory; Genomics Sciences Program; Autonomous University of Mexico City; Mexico DF, Mexico.
2
Virus and Cancer Laboratory; National Institute of Cancerology; Mexico DF, Mexico.
3
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.
4
National Institute of Pediatrics; Biomedical Research Institute; National Autonomous University of Mexico; Mexico DF, Mexico.
5
Molecular Biomedicine Program and Biotechnology Network; National School of Medicine and Homeopathy; National Polytechnic Institute; Mexico DF, Mexico.
6
Cancer Genomics Laboratory; National Institute of Genomic Medicine; Mexico DF, Mexico.
7
Institute of Breast Diseases; FUCAM; Mexico DF, Mexico.
8
Lung Cancer Laboratory; National Institute of Respiratory Diseases; Mexico DF, Mexico.

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.

KEYWORDS:

DNA damage; RAD50 targeting; breast cancer; chemosensitization; chromosomal aberrations; cisplatin; doxorubicin; histone H2AX; paclitaxel

PMID:
24642965
PMCID:
PMC4049793
DOI:
10.4161/cbt.28551
[Indexed for MEDLINE]
Free PMC Article

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