Purpose
Ten eleven translocation (TET) enzyme activity is essential for active DNA demethylation in biological processes, and their altered expression has been observed in various malignancies. Therefore, we investigated DNA methylation and mRNA levels of all TETs in colorectal cancer (CRC) patients.MethodsTET mRNA levels were evaluated using quantitative RT-PCR in primary cancerous and histopathologically unchanged colorectal tissues from patients who underwent radical surgical colon resection (n = 113). DNA methylation levels of the TET CpG island were assessed using bisulfite DNA sequencing and high-resolution melting analysis.ResultsWe found reduced transcript levels of TET1, TET2 and TET3 in cancerous tissue compared with their histopathologically unchanged counterparts (p = 0.000011; p = 0.000001; p = 0.00031, respectively). Importantly, multivariate Cox regression analysis revealed favorable overall survival (OS) and disease-free survival (DFS) outcomes for patients with high TET2 mRNA levels in histopathologically unchanged tissue (HROS = 0.091, 95 % CI 0.011–0.77, p = 0.028; HRDFS = 0.21, 95 % CI 0.04–1.06, p = 0.059). Moreover, we found no DNA methylation in the TET2 and TET3 promoter regions in cancerous and histopathologically unchanged tissue. In contrast, we reported TET1 DNA hypermethylation in a small fraction of patients (n = 12/113).ConclusionTo best of our knowledge, our study is the first to investigate TET mRNA levels in a cohort of CRC patients and correlate them with patients’ prognosis. Present study provides the evidence that TET2 mRNA expression may be an independent prognostic factor for disease recurrence and outcome. Additionally, our findings initially indicate the importance of DNA methylation in regulating TET1 expression.Electronic supplementary materialThe online version of this article (doi:10.1007/s00432-014-1901-2) contains supplementary material, which is available to authorized users.
Dysregulation of estrogen related pathways is implicated colorectal cancer (CRC) development. However, significance of intratissue concentration of estrone (E1) and 17β-estradiol (E2) in relation to estrogen receptor (ESR) expression level was not addressed so far. Herein, we measured E1 and E2 intratissue concentration using liquid chromatography electrospray ionization tandem mass spectrometry (ESI LC/MS) and mRNA levels of ESR1 and ESR2 using RT-qPCR in cancerous and histopathologically unchanged tissue from 75 and 110 CRC patients, respectively. The obtained results were associated with clinicopathological factors, expression of estrogen dependent genes (CTNNB1, CCND1) and prognostic significance. We found no statistically significant differences in E1 or E2 concentration between cancerous tissue and histopathologically unchanged counterparts. Moreover, mRNA levels of ESR1 and ESR2 were significantly decreased in cancerous tissue compared with histopathologically unchanged (p=0.00001). Log rank analysis revealed no benefit of low E1 to E2 ratio, high E1, E2 concentration or ESR1, ESR2 mRNA level for patients’ overall (OS) and disease free survival (DFS). Interestingly, we have observed that patients with low ESR1 mRNA level coupled with low E1 intratissue concentration had a significant decrease in DFS compared with group of patients with high ESR1 mRNA level and high E1 concentration (HR=0.16, 95% CI 0.02-1.05; p=0.06). Furthermore, patients with low E1 concentration and low ESR1 transcript had significantly higher CTNNB1 and CCND1 mRNA level compare with subgroup with high level of both grouping factors. Our study indicates a potential value of estrogen intratissue concentration and its receptor expression level for CRC patients’ prognosis.
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