title: Epidermal growth factor and ionizing radiation up-regulate the DNA repair genes XRCC1 and ERCC1 in DU145 and LNCaP prostate carcinoma through MAPK signaling.
abstract: This work examined the importance of radiation-induced and ligand-induced EGFR-ERK signaling for the regulation of DNA repair proteins XRCC1 and ERCC1 in prostate carcinoma cells, DU145 (TP53(mut)), displaying EGFR-TGFA-dependent autocrine growth and high MAPK (ERK1/2) activity, and LNCaP (TP53(wt)) cells expressing low constitutive levels of ERK1/2 activity. Using quantitative RT-PCR and Western analyses, we determined that ionizing radiation activated the DNA repair genes XRCC1 and ERCC1 in an ERK1/2-dependent fashion for each cell line. After irradiation, a rapid increase followed by a decrease in ERK1/2 activity preceded the increase in XRCC1/ERCC1 expression in DU145 cells, while only the rapid decrease in ERK1/2 preceded the increase in XRCC1/ERCC1 expression in LNCaP cells. Administration of EGF, however, markedly increased the up-regulation of phospho-ERK, ERCC1 and XRCC1 in both cell lines. Although the EGFR inhibitor tyrphostin (AG-1478) and the MEK inhibitor PD90859 both attenuated EGF-induced levels of the ERCC1 and XRCC1 protein, PD98059 blocked the induction of ERCC1 and XRCC1 by radiation more effectively in both cell lines. Inhibition of ERK at a level that reduced the up-regulation of DNA repair led to the persistence of apurinic/apyrimidinic (AP) sites of DNA damage and increased cell killing. Taken together, these data imply a complex control of DNA repair activation that may be more generally dependent on MAPK (ERK1/2) signaling than was previously noted. These data provide novel insights into the capacity of the EGFR-ERK signaling to modulate DNA repair in cancer cells and into the functional significance of this signaling.
authors.affiliation: Department of Radiation Oncology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia 23298, USA.
authors.forename: Adly
authors.initials: A
authors.lastname: Yacoub
authors.forename: Robert
authors.initials: R
authors.lastname: McKinstry
authors.forename: Darin
authors.initials: D
authors.lastname: Hinman
authors.forename: Theodore
authors.initials: T
authors.lastname: Chung
authors.forename: Paul
authors.initials: P
authors.lastname: Dent
authors.forename: Michael P
authors.initials: MP
authors.lastname: Hagan
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D019898:Autocrine Communication; D003037:Cobalt Radioisotopes; D004249:DNA Damage; D004260:DNA Repair / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D004720:Endonucleases; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D066246:ErbB Receptors / Q000187:drug effects / Q000502:physiology*; D005419:Flavonoids / Q000494:pharmacology; D005720:Gamma Rays; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000528:radiation effects; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D011471:Prostatic Neoplasms / Q000473:pathology*; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics; D011799:Quinazolines; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D020032:Tyrphostins / Q000494:pharmacology; D000076105:X-ray Repair Cross Complementing Protein 1
chemical_list: D003037:Cobalt Radioisotopes; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D009363:Neoplasm Proteins; D011506:Proteins; D011799:Quinazolines; D020032:Tyrphostins; D000076105:X-ray Repair Cross Complementing Protein 1; C000619371:XRCC1 protein, human; C101044:RTKI cpd; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C071447:ERCC1 protein, human; D004720:Endonucleases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one