Z Gastroenterol 2010; 48 - A63
DOI: 10.1055/s-0030-1254801

DNA methylation profile in colorectal cancer versus normal colonic tissue – preliminary results

VA Patai 1, O Galamb 2, K Tóth 1, A Kalmár 1, S Spisák 2, B Wichmann 1, O Jász 1, K Leiszter 1, G Valcz 1, F Sipos 1, A Schöller 3, Z Tulassay 2, B Molnár 2
  • 12nd Department of Internal Medicine, Semmelweis University, Budapest
  • 2Molecular Medicine Research Unit, Hungarian Academy of Sciences, Budapest
  • 32nd Department of Surgery, Semmelweis University, Budapest, Hungary

Background: DNA methylation in the promoter region of tumor suppressor genes is a common epigenetic silencing mechanism and has been proved to be a crucial mechanism in colorectal carcinogenesis. To our knowledge, no studies have been performed so far analyzing DNA methylation profile of colorectal cancer (CRC) in both serum and tissue samples from matched patients.

Aim: To find DNA methylation markers that appear both in biopsy tissue and in plasma and accordingly determine a set of DNA methylation markers that could be used as a diagnostic tool to detect CRC at an early stage.

Method: At the present stage of our study we have so far examined 1 CRC and 1 normal colonic biopsy samples. Both patients were women, aged 71. Endoscopically obtained biopsies were stored at -80°C. DNA was isolated and applied for Methyl-Profiler DNA Methylation PCR array system, that was specifically designed for colorectal cancer. Primers of 96 genes, whose aberrant methylation had been reported in gastrointestinal cancer, was lyophilized to the appropriate wells of a 384-well plate. Using methylation restriction enzyme digestion followed by real-time PCR enabled us to define the methylation status in our samples.

Results: According to our preliminary results from the comparison of two profiles, 39 genes were methylated only in the CRC sample, 34 of them already known in the literature. However, 5 novel genes were found, whose methylation had not been described in CRC previously, including ALDH1A3, DACT2, MCC, PAX2, PCDH10.

Conclusions: These preliminary results are consistent with published data, and shows that our approach is capable to identify new tumor suppressor candidates. Our further aim is to examine the methylation status of more biopsy samples and to analyze matched plasma samples parallelly. Such profiles would provide invaluable insight into mechanisms underlying the relationship between methylated DNA markers in colon and peripheral blood and may yield new molecular markers, which could radically improve early cancer detection.