PT  - JOURNAL ARTICLE
AU  - Christof Seidl
AU  - Annette Frank
AU  - Birgit Pfost
AU  - Alfred Morgenstern
AU  - Frank Bruchertseifer
AU  - Reingard Senekowitsch-Schmidtke
TI  - Analysis of DNA double-strand breaks in gastric cancer cells after treatment with 213Bi-immunoconjugates
DP  - 2009 May 01
TA  - Journal of Nuclear Medicine
PG  - 637--637
VI  - 50
IP  - supplement 2
4099  - http://jnm.snmjournals.org/content/50/supplement_2/637.short
4100  - http://jnm.snmjournals.org/content/50/supplement_2/637.full
SO  - J Nucl Med2009 May 01; 50
AB  - 637 Objectives To facilitate dosimetric calculations in α-emitter therapy, new concepts, preferably based on biological models, are needed. Since cytotoxicity of α-particles is due to induction of DNA double-strand breaks (DSBs), detection of DSBs should be a straightforward concept. At sites of DSBs histones H2AX are phosphorylated, resulting in γ-H2AX. Using an antibody that specifically binds to γ-H2AX, the numbers of DSBs can be correlated to the α-emitter activity applied. The aim of this study was to quantify DNA-DSBs in gastric cancer cells after incubation with 213Bi-immunoconjugates. Methods The monoclonal antibody d9MAb specifically binds to HSC45-M2 gastric cancer cells expressing mutant d9-E-cadherin. HSC45-M2 cells were incubated with different activity concentrations of tumor-specific 213Bi-d9MAb conjugates for 3 h (t½ = 46 min). At different time points after incubation γ-H2AX was detected using immunofluorescence and Western blotting. Results Incubation of HSC45-M2 cells seeded in chamber slides with 1.48 GBq/ml caused massive formation of γ-H2AX foci in the nuclei of treated cells that were not observed in the neighboring chamber incubated with PBS only. Thus, γ-emission during 213Bi decay is unable to induce DSBs while α-particles triggered massive DSBs. Phosphorylation of histone H2AX in HSC45-M2 cells could also be demonstrated via Western blotting. Induction of γ-H2AX foci was dependent on 213Bi-d9MAb activity concentration. Conclusions Detection of DSBs via γ-H2AX foci is a promising concept to evaluate cytotoxicity and to estimate doses in 213Bi-immunotherapy.