Relationship Between Induction of Phosphorylated H2AX and Survival in Breast Cancer Cells Exposed to 111In-DTPA-hEGF

Journal of Nuclear Medicine

Kristy E. Bailey¹  Katherine A. Vallis¹  Zhuo Chen¹  Deborah A. Scollard¹  Zhongli Cai¹  Raymond M. Reilly¹ 

关键词: Auger electrons;    H2AX;    ¹¹¹In-DTPA-hEGF;    epidermal growth factor receptor;   

DOI  :  10.2967/jnumed.108.051805

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

The Auger electron–emitting radiopharmaceutical 111In-diethylenetriaminepentaacetic acid human epidermal growth factor (111In-DTPA-hEGF) binds the epidermal growth factor receptor (EGFR), is internalized, and translocates to the nucleus. The purpose of this study was to investigate the relationship between EGFR expression, DNA damage, and cytotoxicity in cells exposed to 111In-DTPA-hEGF. Methods: Breast cancer cell lines with a range of EGFR expression levels were exposed to 111In-DTPA-hEGF or γ-radiation. The cell lines (followed by number of EGFR per cell in parentheses) were MDA-MB-468 (1.3 × 106), MDA-MB-231 (1.3 × 105), and MCF-7 (1.5 × 104). The proportion of radioactivity partitioning into the nucleus was measured by cell fractionation. DNA double-strand breaks were evaluated using the γ-H2AX assay. Clonogenic survival assays were used to measure cytotoxicity. Results: All data are presented as mean ± SD. The amount of 111In-DTPA-hEGF that translocated to the nucleus (in mBq/nucleus) in MDA-MB-468, MDA-MB-231, and MCF-7 cells incubated with 111In-DTPA-hEGF (5.2 MBq/mL, 43 nM) for 20 h was 131 ± 6, 8.1 ± 0.1, and 1.1 ± 0.9, respectively. The number of γ-H2AX foci per nucleus was 35 ± 15, 19 ± 10, and 1.7 ± 0.3, respectively. A reduction in the surviving fraction (SF) in MDA-MB-468 (0.013 ± 0.001) and MDA-MB-231 (0.5 ± 0.1) but not in MCF-7 cells after exposure to 111In-DTPA-hEGF (5.2 MBq/mL, 43 nM) for 20 h has been demonstrated. The SF of MDA-MB-468 cells after exposure to DTPA-EGF (43 nM) and 111In-acetate (5.2 MBq/mL) for 20 h was 0.5 ± 0.1 and 0.53 ± 0.05, respectively. MDA-MB-468 was the most sensitive of the cell lines to γ-irradiation, with an SF after 2 Gy of 0.45 ± 0.04, compared with 0.7 ± 0.1 and 0.8 ± 0.1 for MCF-7 and MDA-MB-231, respectively. The number of γ-H2AX foci per nucleus in MDA-MB-468 cells correlated with the concentration, specific activity, and incubation time of 111In-DTPA-hEGF. Conclusion: DNA damage caused by 111In-DTPA-hEGF correlates with the EGFR expression level of the exposed cells and with concentration, specific activity, and incubation time of 111In-DTPA-hEGF. The γ-H2AX assay may be a useful biomarker to predict and monitor the outcome of treatment with 111In-DTPA-hEGF.

【 授权许可】

Unknown