Differential DNA methylome profiling of nonfunctioning pituitary adenomas suggesting tumour invasion is correlated with cell adhesion

Global and gene-specific changes to the epigenome are hallmarks of most tumours including those of pituitary origin, and this fact might offer important clues about diagnostic and therapeutic applications. We performed global DNA methylation screening with 6 invasive and 6 noninvasive nonfunctioning pituitary adenomas (PA) to investigate whether DNA methylation was associated with the invasion of nonfunctioning pituitary adenomas. An additional seven PAs were included as an independent cohort to validate the initial results. Five thousand nine hundred thirty-one CpGs were selected (△β ≥0.15 and p value ≤0.01) as differentially methylated sites (DMSs). The hypomethylated DMSs in the invasive PAs were significantly more than the hypermethylated sites. Cluster analysis of 339 CpGs (△β ≥0.25 and p value ≤0.001) demonstrated a complete distinction between the invasive and noninvasive nonfunctioning groups. GO analysis of the three hundred seven corresponding genes shown they were involved in homophilic cell adhesion, cell–cell adhesion, cell adhesion and biological adhesion. The mRNA expression of GALNT9 which contain a validated DMS was significantly downregulated in invasive group. Our findings indicate that the differential DNA methylome profiling of invasive and noninvasive nonfunctioning PAs suggesting tumour invasion is correlated with cell adhesion.