To examine the potential activity of TSA in human NPC, we used TSA to treat the poorly differentiated human NPC cell line CNE2 and undifferentiated C666–1 cells and found that TSA effectively attenuated both CNE2 and C666–1 cell proliferation, as evidenced by the suppressed cell viability and PCNA expression. This evidence concerns the gene PCNA and nasopharyngeal carcinoma.