Drug sensitivity profile of NPC268 and other NPC cell lines show preferential sensitivity of NPC268 toward BCL2 inhibitors. A, High-throughput screening on 339 drugs was performed on NPC268 and other NPC cell lines (EBV-negative: NPC38, NPC53, HK1; EBV-positive: NPC43, C666-1, C17). Heat map shows the drug sensitivity of the seven NPC cell lines for the 125 active drugs (at least one cell line with IC50 <1 µmol/L). B, Heat map shows the drug sensitivity toward the six active drugs targeting apoptosis pathways. C, NPC268 is the most sensitive NPC line toward drugs targeting the antiapoptotic proteins such as obatoclax, sabutoclax, and TW37. D,BCL2L2 gene expression is found to be significantly correlated with sensitivity toward obatoclax mesylate, an inhibitor of BCL2L2 (Pearson R = −0.776, P = 0.040). E, Sanger sequencing confirmed the E17K mutation in AKT1 gene, showing an “A” instead of reference allele “G”, leading to a change in amino acid of glutamine (E) to lysine (K) at the 17th amino acid position. F, Bar charts showing the ln IC50 of seven NPC cell lines toward four compounds targeting the PI3K/AKT/MTOR pathways, with NPC268 being the most sensitive line relative to other NPC cell lines.
ARTICLE ABSTRACT
Nasopharyngeal carcinoma (NPC), a cancer that is etiologically associated with the Epstein-Barr virus (EBV), is endemic in Southern China and Southeast Asia. The scarcity of representative NPC cell lines owing to the frequent loss of EBV episomes following prolonged propagation and compromised authenticity of previous models underscores the critical need for new EBV-positive NPC models. Herein, we describe the establishment of a new EBV-positive NPC cell line, designated NPC268 from a primary non-keratinizing, differentiated NPC tissue. NPC268 can undergo productive lytic reactivation of EBV and is highly tumorigenic in immunodeficient mice. Whole-genome sequencing revealed close similarities with the tissue of origin, including large chromosomal rearrangements, while whole-genome bisulfite sequencing and RNA sequencing demonstrated a hypomethylated genome and enrichment in immune-related pathways, respectively. Drug screening of NPC268 together with six other NPC cell lines using 339 compounds, representing the largest high-throughput drug testing in NPC, revealed biomarkers associated with specific drug classes. NPC268 represents the first and only available EBV-positive non-keratinizing differentiated NPC model, and extensive genomic, methylomic, transcriptomic, and drug response data should facilitate research in EBV and NPC, where current models are limited.
NPC268 is the first and only EBV-positive cell line derived from a primary non-keratinizing, differentiated nasopharyngeal carcinoma, an understudied but important subtype in Southeast Asian countries. This model adds to the limited number of authentic EBV-positive lines globally that will facilitate mechanistic studies and drug development for NPC.
