Tumor LINE-1 methylation level and microsatellite instability in relation to colorectal cancer prognosis

J Natl Cancer Inst. 2014 Sep 4;106(9):dju195. doi: 10.1093/jnci/dju195. Print 2014 Sep.

Abstract

Background: Hypomethylation in long interspersed nucleotide element-1 (LINE-1) and high-degree microsatellite instability (MSI-high) in colorectal cancer (CRC) have been associated with inferior and superior survival, respectively; however, it remains uncertain whether the prognostic association of LINE-1 hypomethylation differs by MSI status. We hypothesized that the adverse prognostic association of LINE-1 hypomethylation might be stronger in MSI-high CRCs than in microsatellite stable (MSS) CRCs.

Methods: Utilizing 1211 CRCs in the Nurses' Health Study and the Health Professionals Follow-up Study, we examined patient survival according to LINE-1 hypomethylation status in strata of MSI status. A Cox proportional hazards model was used to compute multivariable CRC-specific mortality hazard ratios (HRs) for a 10% decrease in LINE-1 methylation level (range = 23.1-93.1%), adjusting for potential confounders, including CpG island methylator phenotype, and KRAS, BRAF, and PIK3CA mutations. Statistical tests (log-rank test, chi-square test, and likelihood ratio test) were two-sided.

Results: In MSI-high cancers, the association of LINE-1 hypomethylation with higher mortality (HR = 2.45, 95% confidence interval [CI] = 1.64 to 3.66, P < .001) was stronger than that in MSS cancers (HR = 1.10, 95% CI = 0.98 to 1.24, P = .11) (P interaction < .001, between LINE-1 and MSI statuses). In MSI-high cases with CRC family history, the association of LINE-1 hypomethylation with higher mortality (HR = 5.13, 95% CI = 1.99 to 13.2; P < .001) was stronger than that in MSI-high cases without CRC family history (HR = 1.62, 95% CI = 0.89 to 2.94, P = .11) (P interaction = .02, between LINE-1 and CRC family history statuses).

Conclusions: The association of LINE-1 hypomethylation with inferior survival is stronger in MSI-high CRCs than in MSS CRCs. Tumor LINE-1 methylation level may be a useful prognostic biomarker to identify aggressive carcinomas among MSI-high CRCs.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Bias
  • Chi-Square Distribution
  • Cohort Studies
  • Colorectal Neoplasms / genetics
  • Colorectal Neoplasms / metabolism*
  • Colorectal Neoplasms / mortality*
  • Colorectal Neoplasms / pathology
  • DNA Methylation*
  • Female
  • Humans
  • Kaplan-Meier Estimate
  • Long Interspersed Nucleotide Elements / genetics*
  • Male
  • Microsatellite Instability*
  • Middle Aged
  • Odds Ratio
  • Predictive Value of Tests
  • Prognosis
  • Proportional Hazards Models
  • United States / epidemiology