Imaging DNA damage in vivo using gammaH2AX-targeted immunoconjugates

Area of Science:

• Biomedical Imaging
• Molecular Biology
• Oncology

Background:

• DNA damage responses (DDR) are crucial in cancer development and treatment.
• Current methods for imaging DNA damage in vivo are limited.
• Targeting DDR proteins like γH2AX offers a potential imaging strategy.

Purpose of the Study:

• To develop and validate novel imaging probes for real-time detection of DNA double-strand breaks in vivo.
• To assess the utility of these probes for cancer diagnosis and treatment monitoring.

Main Methods:

• Development of fluorophore (Cy3) and radioisotope ((111)In) labeled immunoconjugates targeting γH2AX.
• Antibodies were conjugated with diethylenetriaminepentaacetic acid (DTPA) for radioisotope labeling and a cell-penetrating peptide (Tat) for nuclear translocation.
• In vitro validation using confocal microscopy in irradiated breast cancer cells.
• In vivo evaluation in a mouse xenograft model of human breast cancer using fluorescence and single photon emission computed tomography (SPECT) imaging.

Main Results:

• Immunoconjugates successfully localized with γH2AX foci in irradiated cells.
• (111)In-labeled probes showed enhanced retention in cells compared to non-specific conjugates.
• In vivo imaging demonstrated that fluorescent and SPECT signals in tumors correlated with radiation dose and γH2AX levels.
• Probes effectively tracked DNA damage after X-ray irradiation and bleomycin treatment.

Conclusions:

• Radioimmunoconjugates targeting γH2AX provide a noninvasive method for monitoring DNA damage.
• These probes have significant potential for preclinical and clinical applications in cancer diagnosis and therapy response assessment.