Identification of Apolipoprotein E as a Potential Diagnostic Biomarker of Nasopharyngeal Carcinoma

PURPOSE: Apo-E, a secreted protein, is closely related to the migration and invasion of tumor cells. In this study, we aimed to analyze the expression of Apo-E in nasopharyngeal carcinoma (NPC) patients and cell lines, as well as its effects on NPC cell behavior. PATIENTS AND METHODS: Our study included 35 patients with NPC from Zhongnan Hospital. Expression levels of Apo-E in patients with NPC were examined by quantitative reverse transcription-polymerase chain reaction, Western blot, and immunohistochemical (IHC) staining. Receiver operating characteristic (ROC) curves were analyzed using the SPSS 22 software to estimate the sensitivity and specificity of the Apo-E protein in diagnosing NPC. Additionally, the level of Apo-E in NPC cell lines (NP69, 6–10B, and 5–8F) was investigated by Western blotting and IHC. RESULTS: Levels of Apo-E were higher in NPC patients than in controls. Moreover, ROC analysis revealed that increased Apo-E in the serum of NPC patients may act as a potential biomarker for NPC diagnosis (Area under the curve 0.917). Furthermore, similar results were also identified in NPC cancer cell lines. RNA interference technology was used to overexpress the endogenous Apo-E in the NPC cell line 6–10B. Wound healing and transwell assays indicated that the overexpression of Apo-E increased the number of cell colonies and migration ability, respectively. CONCLUSION: In this study, we found that Apo-E was elevated in NPC patients and may act as a potential biomarker for NPC diagnosis. In addition, Apo-E was upregulated in NPC cell lines and promoted cell growth, migration, and invasion.