He Y, et al. - Researchers assessed PCDH17 promoter methylation status in nasopharyngeal carcinoma (NPC) cell lines as well as 42 NPC patient specimens. They also investigated how the expression and functions of PCDH17 in NPC were influenced by it. Using reverse transcription PCR, methylation-specific PCR, and bisulfite genome sequencing, the mRNA levels and promoter methylation status of PCDH17 were determined. They used an in vivo subcutaneous tumor model as well as colony formation, cell proliferation, wound healing, in vitro human umbilical vein endothelial cells tube formation, migration, invasion, cell cycle, and apoptosis assays to assess the impacts of ectopic PCDH17 expression in NPC cell lines. They noted that 100% of the NPC cell lines (5/5) exhibited almost absent or significantly attenuated expression of PCDH17, which was restored with 5-aza-2′-deoxycytidine and trichostatin A treatment. Overall, a tumor suppressor role of PCDH17 in NPC was suggested. PCDH17 methylation, possibly a tumor-specific event, could be used as an epigenetic biomarker for NPC.