- 作者：Ting-Yang Lin ; Joseph Tung-Chieh Chang ; Hung-Ming Wang ; Shih-Hsuan Chan ; Chi-Ching Chiu ; Chien-Yu Lin ; Kang-Hsing Fan ; Chun-Ta Liao ; I-How Chen ; Tsan Z. Liu ; Hsiao-Fang Li ; Ann-Joy Cheng
- 刊名：International Journal of Radiation Oncology*Biology*Physics
- 出版年：2010
- 出版时间：1 September 2010
- 年：2010
- 卷：78
- 期：1
- 页码：246-256
- 全文大小：1025 K
Purpose
Radiotherapy is an integral part of the treatment modality for head-neck cancer (HNC), but in some cases the disease is radioresistant. We designed this study to identify molecules that may be involved in this resistance.Methods and Materials
Two radioresistant sublines were established by fractionated irradiation of the HNC cell lines, to determine differentially proteins between parental and radioresistant cells. Proteomic analysis and reverse-transcription polymerase chain reaction were used to identify and confirm the differential proteins. The siRNA knockdown experiments were applied to examine cellular functions of a radioresistant gene, with investigation of the alterations in colonogenic survival, cell cycle status, and reactive oxygen species levels. Xenografted mouse tumors were studied to validate the results.
Results
IN all, 64 proteins were identified as being potentially associated with radioresistance, which are involved in several cellular pathways, including regulation of stimulus response, cell apoptosis, and glycolysis. Six genes were confirmed to be differentially expressed in both radioresistant sublines, with Gp96, Grp78, HSP60, Rab40B, and GDF-15 upregulated, and annexin V downregulated. Gp96 was further investigated for its functions in response to radiation. Gp96-siRNA transfectants displayed a radiation-induced growth delay, reduction in colonogenic survival, increased cellular reactive oxygen species levels, and increased proportion of the cells in the G2/M phase. Xenograft mice administered Gp96-siRNA showed significantly enhanced growth suppression in comparison with radiation treatment alone (p = 0.009).
Conclusions
We identified 64 proteins and verified 6 genes that are potentially involved in the radioresistant phenotype. We further demonstrated that Gp96 knockdown enhances radiosensitivity both in cells and in vivo, which may lead to a better prognosis of HNC treatment.