Circulating cell-free methylated DNA and lactate dehydrogenase release in colorectal cancer.
BACKGROUND
Hypermethylation of DNA is an epigenetic alteration commonly found in colorectal cancer (CRC) and can also be detected in blood samples of cancer patients. Methylation of the genes helicase-like transcription factor (HLTF) and hyperplastic polyposis 1 (HPP1) have been proposed as prognostic, and neurogenin 1 (NEUROG1) as diagnostic biomarker. However the underlying mechanisms leading to the release of these genes are unclear. This study aimed at examining the possible correlation of the presence of methylated genes NEUROG1, HLTF and HPP1 in serum with tissue breakdown as a possible mechanism using serum lactate dehydrogenase (LDH) as a surrogate marker. Additionally the prognostic impact of these markers was examined.


METHODS
Pretherapeutic serum samples from 259 patients from all cancer stages were analyzed. Presence of hypermethylation of the genes HLTF, HPP1, and NEUROG1 was examined using methylation-specific quantitative PCR (MethyLight). LDH was determined using an UV kinetic test.


RESULTS
Hypermethylation of HLTF and HPP1 was detected significantly more often in patients with elevated LDH levels (32% vs. 12% [p = 0.0005], and 68% vs. 11% [p < 0.0001], respectively). Also, higher LDH values correlated with a higher percentage of a fully methylated reference in a linear fashion (Spearman correlation coefficient 0.18 for HLTF [p = 0.004]; 0.49 [p < .0001] for HPP1). No correlation between methylation of NEUROG1 and LDH was found in this study. Concerning the clinical characteristics, high levels of LDH as well as methylation of HLTF and HPP1 were significantly associated with larger and more advanced stages of CRC. Accordingly, these three markers were correlated with significantly shorter survival in the overall population. Moreover, all three identified patients with a worse prognosis in the subgroup of stage IV patients.


CONCLUSIONS
We were able to provide evidence that methylation of HLTF and especially HPP1 detected in serum is strongly correlated with cell death in CRC using LDH as surrogate marker. Additionally, we found that prognostic information is given by both HLTF and HPP1 as well as LDH. In sum, determining the methylation of HLTF and HPP1 in serum might be useful in order to identify patients with more aggressive tumors.
Alexander B
AB
Philipp
Dorothea
D
Nagel
Petra
P
Stieber
Rolf
R
Lamerz
Isabel
I
Thalhammer
Andreas
A
Herbst
Department of Medicine II, Ludwig-Maximilians-Universität München, Marchioninistr, 15, 81377 Munich, Germany. Frank.Kolligs@med.uni-muenchen.de.
Frank T
FT
Kolligs
D000368:Aged; D000369:Aged, 80 and over; D051792:Basic Helix-Loop-Helix Proteins / Q000097:blood / Q000235:genetics; D014408:Biomarkers, Tumor / Q000097:blood; D015179:Colorectal Neoplasms / Q000097:blood / Q000235:genetics* / Q000473:pathology; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000097:blood / Q000235:genetics*; D005260:Female; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000097:blood*; D008297:Male; D008565:Membrane Proteins / Q000097:blood / Q000235:genetics*; D009363:Neoplasm Proteins / Q000097:blood / Q000235:genetics*; D009367:Neoplasm Staging; D009360:Neoplastic Cells, Circulating; D009419:Nerve Tissue Proteins / Q000097:blood / Q000235:genetics; D011379:Prognosis; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000097:blood / Q000235:genetics*
D051792:Basic Helix-Loop-Helix Proteins; D014408:Biomarkers, Tumor; D004268:DNA-Binding Proteins; D007770:L-Lactate Dehydrogenase; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D014157:Transcription Factors; C100023:HLTF protein, human; C105389:NEUROG1 protein, human; C423567:TMEFF2 protein, human