Radiosensitivity in breast cancer assessed by the histone γ-H2AX and 53BP1 foci

Abstract

BackgroundHigh expression of constitutive histone γ-H2AX, a sensitive marker of DNA damage, might be indicative of defective DNA repair pathway or genomic instability. 53BP1 (p53-binding protein 1) is a conserved checkpoint protein with properties of a DNA double-strand breaks sensor. This study explores the relationship between the clinical radiosensitivity of tumor patients and the expression/induction of γ-H2AX and 53BP1 in vitro.MethodsUsing immunostaining, we assessed spontaneous and radiation-induced foci of γ-H2AX and 53 BP1 in peripheral blood mononuclear cells derived from unselected breast cancer (BC) patients (n=57) undergoing radiotherapy (RT). Cells from apparently healthy donors (n=12) served as references.ResultsNon-irradiated cells from controls and unselected BC patients exhibited similar baseline levels of DNA damage assessed by γ-H2AX and 53BP1 foci. At the same time, the γ-H2AX assay of in vitro irradiated cells revealed significant differences between the control group and the group of unselected BC patients with respect to the initial (0.5 Gy, 30 min) and residual (2 Gy, 24 h post-radiation) DNA damage. The numbers of 53BP1 foci analyzed in 35 BC patients were significantly higher than in controls only in case of residual DNA damage. A weak correlation was found between residual foci of both proteins tested. In addition, cells from cancer patients with an adverse acute skin reaction (grade 3) to RT showed significantly increased radiation-induced γ-H2AX foci and their protracted disappearance compared to the group of BC patients with normal skin reaction (grade 0–1). The mean number of γ-H2AX foci after 5 clinical fractions was significantly higher than that before RT, especially in clinically radiosensitive patients.ConclusionsThe γ-H2AX assay may have potential for screening individual radiosensitivity of breast cancer patients.Trial registrationhttp://www.krebshilfe.de/wir-foerdern.html

PET imaging of DNA damage using 89Zr-labelled anti-γH2AX-TAT immunoconjugates

“…In some cases, overexpression of γH2AX is even a better histological marker than the gold standard method, as is the case for metastatic renal cell carcinoma, where markers such as RCC marker, have been employed with varying success [29]. Also, γH2AX imaging may be used as an aid for staging or use as a prognostic biomarker, by determining genetic instability of diagnosed tumours [8,9,30] or hypersensitivity of normal tissues [31,27]. Finally, imaging DSBs using PET has applications in therapy evaluation of chemo-and radiotherapy, where short-term individualized window studies could shed light on the usefulness of treatments or treatment combinations [7,32,33].…”

Knockdown of CAVEOLIN-1 Sensitizes Human Basal-Like Triple-Negative Breast Cancer Cells to Radiation

“…As depicted in Fig. 5B, few foci representing γ-H2AX, which is a marker of DNA damage, could be observed in non-irradiated cells [35]. Radiation induced a significant increase in γ-H2AX 12 h after irradiation in the presence or absence of CAV-1 siRNA.…”

Persistent γH2AX: A promising molecular marker of DNA damage and aging

“…The remaining 40% of DSBs repair slowly, with a repairing half-life in the range of 1.5-8 h [59][60][61][62][63]. DSBs measured several hours after an initial radiation exposure that still remain unrepaired, may be predictive of individual radiosensitivity to complex DNA lesions that can be lethal [64][65][66]. The rate of gH2AX foci loss and the presence of residual foci has also been correlated with cellular radiosensitivity and absorbed radiation dose [47,56,[67][68][69][70][71].…”