Clinical and prognostic relevance of methylation of circulating HLTF and HPP1 tumor DNA and CEA in serum of patients with colorectal carcinoma (CRC).

Abstract

3611 Background: Hypermethylation of CpG islands is a frequent epigenetic alteration in CRC. We identified helicase-like transcription factor (HLTF) and hyperplastic polyposis 1 (HPP1)as methylation markers in serum of patients with CRC. So far no data is available on the prognostic relevance of these genes when found in serum of patients with metastasized tumors. The aim of this study was to elucidate the prognostic relevance of methylated HLTFand HPP1DNA compared to carcinoembryonic antigen (CEA) in serum of patients with metastasized CRC. Methods: We examined pretherapeutic sera of 311 patients with CRC (208 UICC I-III, 103 UICC IV). CEA was determined using the AXsym system (Abbott Diagnostics). Circulating free DNA was extracted from the serum samples. After bisulfite treatment of the DNA, quantitative realtime PCR was performed to determine the amount of methylated HTLF and HPP1 DNA. Survival analysis was performed using the Kaplan-Meier method and logrank tests. Hazard ratios were estimated using Cox proportional hazard method. Results: Serum methylation of HLTF and HPP1 was found in 11% (n=23/208) and 5% (n=11/208) of UICC I-III and 24% (n=25/103) and 51% (n=53/103) of UICC IV patients. Methylation of the genes HLTF (p=0.0024) and HPP1 (p<0.0001) occurred significantly more frequently in sera of patients with metastasized CRC than in patients without distant metastases. Overall survival for patients with stage IV disease was shortened when serum methylation of HLTF (19.7 vs. 10.0 months, p=0.0005) or HPP1 (23.2 vs. 10.5 months, p=0.0003) or high levels of CEA (cutoff 27 ng/mlL, median of UICC IV group) (26.8 vs. 12.9 months, p=0.0020) was found. Multivariate analysis showed that methylation of HLTF (HR 1.8, 95% CI 1.0-3.0, p=0.0438) and HPP1 (HR 1.6, 95% CI 1.0-2.7, p=0.0495) as well as CEA (HR 1.7, 95% CI 1.0-2.7, p=0.0317) are independent prognostic factors in UICC IV patients. Conclusions: Detection of methylated HLTF or HPP1 DNA and elevated CEA in serum of patients with metastasized CRC is correlated with worse prognosis. Therefore, HLTF and HPP1 could supplement the current standard CEA as a serum prognostic marker.Prospective studies need to confirm these results.