Analysis of DNA double-strand breaks in gastric cancer cells after treatment with 213Bi-immunoconjugates

Objectives: To facilitate dosimetric calculations in -emitter therapy, new concepts, preferably based on biological models, are needed. Since cytotoxicity of -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 -H2AX. Using an antibody that specifically binds to -H2AX, the numbers of DSBs can be correlated to the -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 (t = 46 min). At different time points after incubation -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 -H2AX foci in the nuclei of treated cells that were not observed in the neighboring chamber incubated with PBS only. Thus, -emission during 213Bi decay is unable to induce DSBs while -particles triggered massive DSBs. Phosphorylation of histone H2AX in HSC45-M2 cells could also be demonstrated via Western blotting. Induction of -H2AX foci was dependent on 213Bi-d9MAb activity concentration. Conclusions: Detection of DSBs via -H2AX foci is a promising concept to evaluate cytotoxicity and to estimate doses in 213Bi-immunotherapy.

SEIDL C.;  FRANK Annette;  PFOST B.;  MORGENSTERN Alfred;  BRUCHERTSEIFER Frank;  SENEKOWITSCH-SCHMIDTKE Reingard; 

2012-04-06

SOC NUCLEAR MEDICINE INC

JRC55684

0161-5505,   

http://jnumedmtg.snmjournals.org/cgi/content/meeting_abstract/50/2_MeetingAbstracts/637,    https://publications.jrc.ec.europa.eu/repository/handle/JRC55684,