LINE-1 methylation level and prognosis in pancreas cancer: pyrosequencing technology and literature review.

PURPOSE

Global DNA hypomethylation plays an important role in genomic instability and carcinogenesis. The long interspersed nucleotide element-1 (LINE-1) methylation level is a good surrogate marker of the global DNA methylation level. Previously, we demonstrated a strong relationship between LINE-1 hypomethylation and poor prognosis in certain cancers. However, the relationship between the LINE-1 methylation level and the clinical outcome of pancreatic cancer (PC) remains unclear.

METHODS

We used a pyrosequencing assay to measure LINE-1 methylation levels in 126 samples of resected PC and evaluated the prognostic value of the LINE-1 methylation level.

RESULTS

LINE-1 methylation levels were significantly lower in PC tissues than in matched noncancerous pancreatic tissues (p = 0.039, n = 36). The tumoral LINE-1 methylation range was 41.3-92.8 (n = 126, mean 77.7, median 78.5, standard deviation 5.7). The LINE-1 methylation level was unrelated to clinical and pathological features. Moreover, LINE-1 hypomethylation was not significantly associated with overall survival, cancer specific survival, or disease-free survival (log-rank p = 0.30, p = 0.18 and p = 0.50, respectively).

CONCLUSION

The LINE-1 methylation level appears not to be associated with poor prognosis in PC. The effect of the LINE-1 methylation level on the survival of PC patients needs to be confirmed in a larger-cohort study.