- 作者：Ping Li ; M.D.&lowast ; ; Qing Zhang ; M.D.&lowast ; ; Artour Torossian ; B.S.&dagger ; ; Zhao-bin Li ; B.S.&lowast ; ; Wen-cai Xu ; M.D.&lowast ; ; Bo Lu ; M.D. ; Ph.D.&Dagger ; ; Shen Fu ; M.D. ; Ph.D.&lowast ; ; fushen1117@gmail.com
- 关键词：Radiosensitivity ; Epidermal growth factor receptor (EGFR) ; Phosphoinositide 3-kinase (PI3K) ; Protein kinase B (Akt/PKB) ; Breast cancer ; Co-targeting inhibition
- 刊名：International Journal of Radiation Oncology*Biology*Physics
- 出版年：2012
- 期刊代码：136_03603016
- 类别：med
- 出版时间：1 July, 2012
- 卷：83
- 期：3
- 页码：e391-e397
- 文件大小：776 K
Purpose
Mutations in the epidermal growth factor receptor (EGFR)/phosphoinositide 3-kinase (PI3K)/Akt signaling transduction pathway are common in cancer. This pathway is imperative to the radiosensitivity of cancer cells. We aimed to investigate the radiosensitizing effects of the simultaneous inhibition of EGFR and PI3K in breast cancer cells.Methods and Materials
MCF-7 cell lines with low expression of EGFR and wild-type PTEN and MDA-MB-468 cell lines with high expression of EGFR and mutant PTEN were used. The radiosensitizing effects by the inhibition of EGFR with AG1478 and/or PI3K with Ly294002 were determined by colony formation assay, Western blot was used to investigate the effects on downstream signaling. Flow cytometry was used for apoptosis and cell cycle analysis. Mice-bearing xenografts of MDA-MB-468 breast cancer cells were also used to observe the radiosensitizing effect.
Results
Simultaneous inhibition of EGFR and PI3K greatly enhanced radiosensitizing effect in MDA-MB-468 in terms of apoptosis and mitotic death, either inhibition of EGFR or PI3K alone could enhance radiosensitivity with a dose-modifying factor (DMFSF2) of 1.311 and 1.437, radiosensitizing effect was further enhanced by simultaneous inhibition of EGFR and PI3K with a DMFSF2 at 2.698. DNA flow cytometric analysis indicated that dual inhibition combined with irradiation significantly induced G0/G1 phase arrest in MDA-MB-468 cells. The expression of phosphor-Akt and phosphor-Erk1/2 (induced by irradiation and PI3K inhibitor) were fully attenuated by simultaneous treatment with both inhibitors in combination with irradiation. In addition, dual inhibition combined with irradiation induced dramatic tumor growth delay in MDA-MB-468 xenografts.
Conclusions
Our study indicated that simultaneous inhibition of EGFR and PI3K could further sensitize the cancer cells to irradiation compared to the single inhibitor with irradiation in聽vitro and in聽vivo. The approach may have important therapeutic implication in the treatment of a subset of breast cancer patients with high expression of EGFR and deficient function of PTEN.