Enhancement of radiosensitivity by dual inhibition of the HER family with ZD1839 ('Iressa') and trastuzumab ('Herceptin')
- Department of Radiology, Tokyo Women's Medical University, School of Medicine, Tokyo (Japan)
Purpose: The aims of this study were twofold: (1) to examine the effects of dual inhibition of 2 members of the HER family, the epidermoid growth factor receptor (EGFR) and HER2/neu, by gefitinib (ZD1839) and trastuzumab on radiosensitivity; and (2) to explore the molecular mechanism of radiosensitization especially focusing on the survival signal transduction pathways by using A431 human vulvar squamous carcinoma cells expressing EGFR and HER2/neu. Methods and Materials: The effects of inhibitors on Radiation-induced activation of EGFR and/or HER2/neu, and the intracellular proteins that are involved in their downstream signaling, were quantified by the Western blot. Radiosensitizing effects by the blockage of EGFR and/or HER2/neu were determined by a clonogenic assay. Results: Radiation-induced activation of the EGFR and HER2/neu was inhibited with ZD1839 and/or trastuzumab. ZD1839 also inhibited Radiation-induced phosphorylation of HER2/neu. Radiation in combination with the HER family inhibitors inhibited the activation of Akt and MEK1/2, the downstream survival signaling of the HER family. ZD1839 enhanced radiosensitivity with a dose-modifying factor (DMF) (SF3) of 1.45 and trastuzumab did so with a DMF (SF3) of 1.11. Simultaneous blockade of EGFR and HER2/neu induced a synergistic radiosensitizing effect with a DMF (SF3) of 2.29. Conclusions: The present data suggest that a dual EGFR and HER2/neu targeting may have potential for radiosensitization in tumors in which both of these pathways are active.
- OSTI ID:
- 20850131
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 66, Issue 2; Other Information: DOI: 10.1016/j.ijrobp.2006.05.036; PII: S0360-3016(06)00954-0; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
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