Epidermal Growth Factor Receptor Inhibition Modulates the Nuclear Localization and Cytotoxicity of the Auger Electron Emitting Radiopharmaceutical 111In-DTPA Human Epidermal Growth Factor
| Autor: | Danny L. Costantini, Zhuo Chen, Zhongli Cai, Kristy E. Bailey, Raymond M. Reilly, Katherine A. Vallis, Deborah A. Scollard |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
medicine.medical_specialty
media_common.quotation_subject Antineoplastic Agents Electrons Gefitinib Epidermal growth factor Cell Line Tumor Internal medicine medicine Humans Radiology Nuclear Medicine and imaging Epidermal growth factor receptor Phosphorylation Clonogenic assay Internalization Fluorescent Dyes media_common Cell Nucleus Epidermal Growth Factor biology Chemistry Indium Radioisotopes Pentetic Acid Molecular biology Cell Compartmentation ErbB Receptors Protein Transport Endocrinology Radionuclide therapy Cancer cell Quinazolines biology.protein Radiopharmaceuticals Tyrosine kinase Fluorescein-5-isothiocyanate Signal Transduction medicine.drug |
| Zdroj: | Journal of Nuclear Medicine. 48:1562-1570 |
| ISSN: | 0161-5505 |
| Popis: | UNLABELLED: (111)In-DTPA-human epidermal growth factor ((111)In-DTPA-hEGF [DTPA is diethylenetriaminepentaacetic acid]) is an Auger electron-emitting radiopharmaceutical that targets EGF receptor (EGFR)-positive cancer. The purpose of this study was to determine the effect of EGFR inhibition by gefitinib on the internalization, nuclear translocation, and cytotoxicity of (111)In-DTPA-hEGF in EGFR-overexpressing MDA-MB-468 human breast cancer cells. METHODS: Western blot analysis was used to determine the optimum concentration of gefitinib to abolish EGFR activation. Internalization and nuclear translocation of fluorescein isothiocyanate-labeled hEGF were evaluated by confocal microscopy in MDA-MB-468 cells (1.3 x 10(6) EGFRs/cell) in the presence or absence of 1 microM gefitinib. The proportion of radioactivity partitioning into the cytoplasm and nucleus of MDA-MB-468 cells after incubation with (111)In-DTPA-hEGF for 24 h at 37 degrees C in the presence or absence of 1 microM gefitinib was measured by cell fractionation. DNA double-strand breaks caused by (111)In were quantified using the gamma-H2AX assay, and radiation-absorbed doses were estimated. Clonogenic survival assays were used to measure the cytotoxicity of (111)In-DTPA-hEGF alone or in combination with gefitinib. RESULTS: Gefitinib (1 microM) completely abolished EGFR phosphorylation in MDA-MB-468 cells. Internalization and nuclear translocation of fluorescein isothiocyanate-labeled EGF were not diminished in gefitinib-treated cells compared with controls. The proportion of internalized (111)In that localized in the nucleus was statistically significantly greater when (111)In-DTPA-hEGF was combined with gefitinib compared with (111)In-DTPA-hEGF alone (mean +/- SD: 26.0% +/- 5.5% vs. 14.6% +/- 4.0%, respectively; P < 0.05). Induction of gamma-H2AX foci was greater in MDA-MB-468 cells that were treated with (111)In-DTPA-hEGF (250 ng/mL, 1.5 MBq/mL) plus gefitinib (1 microM ) compared with those treated with (111)In-DTPA-hEGF alone (mean +/- SD: 35 +/- 4 vs. 24 +/- 5 foci per nucleus, respectively). In clonogenic assays, a significant reduction in the surviving fraction was observed when (111)In-DTPA-hEGF (5 ng/mL, 6 MBq/microg) was combined with gefitinib (1 microM ) compared with (111)In-DTPA-hEGF alone (42.9% +/- 5.7% vs. 22.9% +/- 3.6%, respectively; P < 0.01). CONCLUSION: The efficacy of (111)In-DTPA-hEGF depends on internalization and nuclear uptake of the radionuclide. Nuclear uptake, DNA damage, and cytotoxicity are enhanced when (111)In-DTPA-hEGF is combined with gefitinib. These results suggest a potential therapeutic role for peptide receptor radionuclide therapy in combination with tyrosine kinase inhibitors. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|