title: Decay of γ-H2AX foci correlates with potentially lethal damage repair in prostate cancer cells.
abstract: To determine the relationship between ionizing radiation-induced levels of γ-H2AX foci and cell survival in cultured prostate cancer cell lines, three prostate cancer cell lines: LNCaP (wt TP53), DU145 (mut TP53) and PC3 (TP53 null), were studied. For γ-H2AX foci induction, cells were irradiated with a single dose of 2 Gy and foci levels were studied at 30 min and 24 h after irradiation. Cell survival was determined by clonogenic assay, directly and 24 h after irradiation with doses ranging from 0 to 8 Gy. Irradiation was performed with a Siemens Stabilipan 250 KeV X-ray machine at a dose rate of approximately 3 Gy/min. Survival curves were analyzed using the linear-quadratic model S(D)/S(0)=exp-(αD+βD2). LNCaP cells clearly demonstrated potentially lethal damage repair (PLDR) which was assessed as increased survival levels after delayed plating as compared to cells plated immediately after irradiation. DU145 cells demonstrated only a slight PLDR and PC3 cells did not show PLDR at all. Levels of γ-H2AX foci were significantly decreased in all cell lines at 24 h after irradiation, compared to levels after 30 min. The LNCaP cells which demonstrated a clear PLDR also showed the largest decay in the number of γ-H2AX foci. In addition, the PC cells which did not show PLDR had the lowest decay of γ-H2AX foci. A clear correlation was demonstrated between the degree of decay of γ-H2AX foci and PLDR.
authors.affiliation: Department of Radiation Oncology, Laboratory for Experimental Oncology and Radiobiology (LEXOR), Center for Experimental Molecular Medicine, Academic Medical Center, University of Amsterdam, and Free University Hospital, Amsterdam, The Netherlands.
authors.forename: Bregje
authors.initials: B
authors.lastname: van Oorschot
authors.forename: Suzanne E
authors.initials: SE
authors.lastname: Hovingh
authors.forename: Hans
authors.initials: H
authors.lastname: Rodermond
authors.forename: Ahmed
authors.initials: A
authors.lastname: Güçlü
authors.forename: Nienke
authors.initials: N
authors.lastname: Losekoot
authors.forename: Albert A
authors.initials: AA
authors.lastname: Geldof
authors.forename: Gerrit W
authors.initials: GW
authors.lastname: Barendsen
authors.forename: Lukas J
authors.initials: LJ
authors.lastname: Stalpers
authors.forename: Nicolaas A P
authors.initials: NA
authors.lastname: Franken
mesh_terms: D045744:Cell Line, Tumor; D002470:Cell Survival / Q000528:radiation effects; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D006657:Histones / Q000378:metabolism*; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: C468783:H2AX protein, human; D006657:Histones; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53