<i>PD-L1</i> (<i>CD274</i>) and <i>PD-L2</i> (<i>PDCD1LG2</i>) promoter methylation is associated with HPV infection and transcriptional repression in head and neck squamous cell carcinomas

Abstract

<i>PD-L1</i> and <i>PD-L2</i> promoter methylation and its mRNA expression were analyzed based on Infinium HumanMethylation450 BeadChip and RNA-Seq (both Illumina, Inc.) data in a representative HNSCC patient cohort (<i>n</i> = 528) enrolled by The Cancer Genome Atlas (TCGA) Research Network. A validation cohort consisting of 168 HNSCC patients treated at the University Hospital Bonn was analyzed regarding <i>PD-L1</i> and <i>PD-L2</i> promoter methylation by means of methylation-specific quantitative real-time PCR. PD-L1 protein expression in the validation cohort was quantified via immunohistochemistry (PD-L1 antibody clone 22C3, Dako/Agilent Technologies, Inc.).