ErbB-2 Blockade and Prenyltransferase Inhibition Alter Epidermal Growth Factor and Epidermal Growth Factor Receptor Trafficking and Enhance 111In-DTPA-hEGF Auger Electron Radiation Therapy

Journal of Nuclear Medicine

Iain Tullis¹  Raymond Reilly¹  Sonali Darbar¹  Bart Cornelissen¹  Katherine A. Vallis¹  Sean Smart¹  Veerle Kersemans¹  Paul R. Barber¹  Rebecca Hernandez¹  Borivoj Vojnovic¹ 

关键词: EGF;    EGFR;    FRET;    radioimmunotherapy;    trastuzumab;    prenyltransferase inhibitor;    ¹¹¹In;    Auger electrons;   

DOI  :  10.2967/jnumed.110.084392

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

The intracellular distribution of Auger electron–emitting radiopharmaceuticals is a determinant of cytotoxicity. However, the mechanisms by which these agents are routed through the cell are ill understood. The aim of this study was to investigate how trafficking of 111In-labeled human epidermal growth factor (111In-DTPA-hEGF) relates to that of the EGF receptor (EGFR) and whether coadministration of agents that modulate EGFR signaling alters the efficacy of 111In-DTPA-hEGF. Methods: The spatiotemporal interaction between AlexaFluor488-EGF (AF488-EGF) and Cy3-conjugated anti-EGFR antibody (Cy3-anti-EGFR) was studied in the breast cancer cell line MDA-MB-468 using fluorescence resonance energy transfer and 2-photon fluorescence lifetime imaging. 111In internalization and nuclear fractionation assays were performed to investigate the effect of the ErbB-2–blocking antibody trastuzumab and a prenyltransferase inhibitor, L-778,123, on the subcellular localization of 111In-DTPA-hEGF in MDA-MB-468 (1.3 × 106 EGFR per cell; ErbB-2 negative) and 231-H2N (0.2 × 106 EGFR per cell; 0.4 × 105 ErbB-2 per cell) cell lines. The cytotoxicity of 111In-DTPA-hEGF (0–64 nM) plus trastuzumab (0–50 μg/mL) or L-778,123 (0–22.5 μM) was measured using clonogenic assays in a panel of breast cancer cell lines that express different levels of EGFR and ErB-2. Clonogenic survival data were used to calculate combination indices. Tumor growth inhibition was measured in vivo in 231-H2N xenograft–bearing mice treated with 111In-DTPA-hEGF plus trastuzumab or L-788,123. Results: Using fluorescence resonance energy transfer, we showed that EGF interacts with EGFR in the cytoplasm and nucleus after internalization of the ligand–receptor complex in MDA-MB-468 cells. Nuclear localization of 111In-DTPA-hEGF is enhanced by trastuzumab and L-788,123. Trastuzumab and L-788,123 sensitized 231-H2N cells to 111In-DTPA-hEGF. Nuclear localization and cytotoxicity of 111In-DTPA-hEGF were significantly increased in 231-H2N xenografts by cotreatment with L-788,123 (P < 0.0001). Conclusion: The therapeutic efficacy of 111In-DTPA-hEGF is increased through the coadministration of selected molecularly targeted drugs that modulate EGFR signaling and trafficking.

【 授权许可】

Unknown