Epstein-Barr virus latent membrane protein 1 (LMP1) regulates the aldehyde dehydrogenase (ALDH) positive cell population in nasopharyngeal carcinoma cell lines

Abstract

Nasopharyngeal carcinoma (NPC) is one of the severe head and neck carcinomas, which are rare in western countries but with high incidence in Southern Asia especially South China. NPC is relatively sensitive to radiotherapy, but the prognosis of patients in late stage is poor. The development of NPC is closely related to genetic background, Epstein-Barr virus (EBV) infection and life style. EBV latent membrane protein 1 (LMP1) is an oncoprotein, which plays important roles in the tumorigenesis of NPC. LMP1 was reported to be involved in the regulation of cancer stem cells (CSCs) by immunohistochemistry (IHC) and other surface marker staining methods, but not shown by aldehyde dehydrogenase 1 (ALDH-1) functional assay yet. In this study, we overexpressed LMP1 in two NPC cell lines and found elevated level of cytokeratin 19 (CK19) expression. CK19 is an undifferentiated keratin and a stem cell marker. We also have found an increased number of ALDH positive cells along with LMP1 overexpression in both cell lines. Our data demonstrate that LMP1 regulates the maintenance of ALDH-1 positive NPC cancer stem cells, thus shedding light on target therapy of NPC in clinical application.