title: Erlotinib attenuates homologous recombinational repair of chromosomal breaks in human breast cancer cells.
abstract: The epidermal growth factor receptor (EGFR) family has been implicated in several cancers, including breast, and its members have become the target of novel cancer therapies. In this report, we show a novel link between erlotinib, a potent EGFR inhibitor, DNA damage, and homology-directed recombinational repair (HDR) in human breast cancer cells. Erlotinib suppresses HDR. This is not secondary to erlotinib-mediated changes in cell cycle and is associated with increased gamma-H2AX foci, which is an in situ marker of chromosomal double-strand breaks. Both Rad51 and BRCA1 are essential components of the HDR machinery. Consistent with decreased HDR in erlotinib-treated cells, erlotinib also attenuates DNA damage-induced Rad51 foci and results in cytoplasmic retention of BRCA1. As BRCA1 is a shuttling protein and its nuclear function of promoting HDR is controlled by its subcellular localization, we further show that targeted translocation of BRCA1 to the cytoplasm enhances erlotinib sensitivity. These findings suggest a novel mechanism of action of erlotinib through its effects on the BRCA1/HDR pathway. Furthermore, BRCA1/HDR status may be an innovative avenue to enhance the sensitivity of cancer cells to erlotinib.
authors.affiliation: Department of Radiation Oncology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
authors.forename: Liping
authors.initials: L
authors.lastname: Li
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.forename: Eddy S
authors.initials: ES
authors.lastname: Yang
authors.forename: Carlos L
authors.initials: CL
authors.lastname: Arteaga
authors.forename: Fen
authors.initials: F
authors.lastname: Xia
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics; D045744:Cell Line, Tumor; D019457:Chromosome Breakage; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair / Q000187:drug effects*; D066246:ErbB Receptors / Q000037:antagonists & inhibitors*; D000069347:Erlotinib Hydrochloride; D005260:Female; D016193:G1 Phase; D019398:Genes, BRCA1 / Q000502:physiology; D006657:Histones / Q000032:analysis; D006801:Humans; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011799:Quinazolines / Q000494:pharmacology*; D051135:Rad51 Recombinase / Q000032:analysis; D011995:Recombination, Genetic / Q000187:drug effects*
chemical_list: C468783:H2AX protein, human; D006657:Histones; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D000069347:Erlotinib Hydrochloride; D066246:ErbB Receptors; C495153:RAD51 protein, human; D051135:Rad51 Recombinase