Proteome study of nasopharyngeal carcinoma.
Date of Issue2012
School of Chemical and Biomedical Engineering
Nasopharyngeal carcinoma (NPC) is one of the sneakiest cancer frequently occurred in Southeast Asia and southern China. Due to the vague symptoms and difficulty of physical examination, NPC urgently needs efficient approaches to improve its diagnosis, treatments and understanding of the disease. In our study we employ a high-throughput system, iTRAQ-coupled 2D LC-MS/MS, to analyse the protein profiles of patients’ serum and NPC cell lines in response to Epstein-Barr virus (EBV) infection, which is considered as a major factor causing NPC. In the clinical study of patients’ sera, 13 proteins showed significant changes compared with the healthy control. Changed proteins in NPC patients were classified and analysed according to their functions and served as potential biomarker candidates for NPC prognosis. In order to study the influence of EBV infection upon the NPC cell line, a comparative protein profile of NPC cells in response to EBV infection was established by using iTRAQ-coupled 2D LC-MS/MS system. 12 proteins were found to be significantly up-regulated in EBV infected NPC cells. By protein network analysis, a novel pathway was proposed associated with NF-κB signaling pathway and p53 signaling pathway. In the process of NPC cell line proteome study, an up-regulated potential biomarker candidate, voltage dependent anion-selective channel protein 1 (VDAC1), was further explored because of its importance located in the outer membrane of mitochondrial for controlling apoptotic signals. Pro-apoptotic signals Ca2+ and cytochrome C were detected in response to EBV infection. Upon virus infection, cytoplasmic Ca2+ was decreased while cytochrome C was increased. In order to study whether the changes of pro-apoptotic signals was regulated through VDAC1, we used siRNA to inhibit VDAC1’s expression. After inhibition, cytochrome C was back to the same level as that of non-infected cells, indicating cytochrome C release was regulated through VDAC1 during EBV infection. These findings proved that iTRAQ-coupled 2D LC-MS/MS was an efficient approach to study protein profile of nasopharyngeal carcinoma in both clinical serum samples and cell lines. The changes of pro-apoptotic signals Ca2+ and cytochrome C upon EBV infection by using siRNA to inhibit the VDAC1 demonstrate new mechanism of virus infected apoptosis in cancer cells. In summary, these results might provide valuable information to elucidate NPC mechanisms and improve the management of nasopharyngeal carcinoma.