PF540 TERT PROMOTER METHYLATION AS A POTENTIAL PROGNOSTIC BIOMARKER FOR PROGRESSION OF UNEXPLAINED CYTOPENIA TO MDS AND AML
Authors: Kaastrup K. , Gillberg L. , Aslan D. , Kristensen L.S. , Ørskov A.D. , Hansen J.W. , Grønbæk K. 
Published: June 2019

Background:

Patients with myelodysplastic syndrome (MDS) often have mutations in epigenetic regulators and altered DNA methylation in their blood cells. Patients with unexplained cytopenia that do not fulfill the criteria for MDS are referred to as having idiopathic cytopenia of undetermined significance (ICUS) or, if they have MDS‐related mutations, clonal cytopenia of undetermined significance (CCUS).

A previous study (Zhao et al. BJH 2016) showed that acute myeloid leukemia (AML) patients with preceding MDS (MDS/AML) have hypermethylation of the telomerase reverse transcriptase (TERT) promoter compared to healthy controls. Increased TERT promoter methylation may cause impaired telomerase activity and thereby shortening of telomeres and increased risk of progression to AML.

Aims:

We aimed to investigate DNA methylation of the TERT promoter to evaluate its potential as a biomarker of disease severity in patients with unexplained cytopenia and MDS.

Methods:

TERT promoter methylation of two regions (region 1 covering 5 CpG sites 456 to 424 bp upstream of the TSS and region 2 covering 6 CpG sites 384 to 328 bp upstream of the TSS) was analyzed by pyrosequencing in a cohort of 185 patients with ICUS (n = 65), CCUS (n = 49) or MDS (n = 71). Results are presented as DNA methylation percentage of region 1 and 2 (mean ± SD).

Results:

The 185 included patients (111 men, 74 women) had a median age of 69 years (ICUS: 65 years, CCUS: 70 years, MDS: 72 years) and the 15 healthy controls (6 men, 7 women) had a median age of 57 years.

One‐way ANOVA analysis revealed significantly differences in TERT promoter methylation between all groups for both regions (region 1: p = 0.0004, region 2: p = 7.4 × 10–5).

TERT promoter methylation in region 1 was significantly higher in all disease groups compared to healthy controls, with increasing methylation and significance levels with increased disease severity (ICUS: 8.3 ± 4.8, p = 0.03; CCUS: 10.2 ± 7.2, p = 0.0007, MDS: 11.3 ± 7.7, p = 1.9 × 10–6; Figure 1A). Furthermore, TERT promoter methylation levels of both CCUS and MDS patients were significantly higher than ICUS patients (p = 0.02 and p = 1.8 × 10–6, respectively.

In region 2, MDS patients had significantly higher methylation (MDS: 8.8 ± 8.1, p = 0.001) compared to healthy controls (5.4 ± 3.2). TERT promoter methylation of region 2 in ICUS and CCUS patients was not significantly different from healthy controls or MDS patients (Figure 1B).

Figure 1: Box‐and‐whisper plots of TERT promoter methylation percentage in region 1 (A) and region 2 (B) in 185 ICUS, CCUS, MDS patients and 15 age‐matched healthy controls.

Summary/Conclusion:

Promoter methylation of TERT increases gradually from healthy controls to ICUS, CCUS and MDS patients. Our study suggests that DNA methylation of the TERT promoter reflects disease severity of unexplained cytopenia and MDS patients. We are currently investigating if TERT promoter methylation can be used as a biomarker for survival and progression to MDS and AML.

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