CpG island methylation of microRNAs is associated with tumor size and recurrence of non-small-cell lung cancer

We investigated whether the CpG island methylation of certain microRNAs was associated with the clinicopathological features and the prognosis of non-small-cell lung cancer. The methylation of mir-152, -9-3, -124-1, -124-2, and -124-3 was analyzed in 96 non-small-cell lung cancer specimens using a combined bisulfite restriction analysis. The median observation period was 49.5 months. The methylation of mir-9-3, -124-2, and -124-3 was individually associated with an advanced T factor independent of age, sex, and smoking habit. Moreover, the methylation of multiple microRNA loci was associated with a poorer progression-free survival in a univariate analysis. Our result enlightens the accumulation of aberrant DNA methylation which occurs in concordance with the tumor progression.