Septin 9 methylation in colorectal cancer screening using peripheral blood and tissue samples

K Tóth; O Galamb; S Spisák; F Sipos; B Wichmann; K Leiszter; G Valcz; A Kalmár; VÁ Patai; A Schöller; R Wasserkort; Z Tulassay; B Molnár

doi:10.1055/s-0031-1278468

Zeitschrift für Gastroenterologie, Inhaltsverzeichnis

Septin 9 methylation in colorectal cancer screening using peripheral blood and tissue samples

K Tóth ¹, O Galamb ², S Spisák ², F Sipos ¹, B Wichmann ¹, K Leiszter ¹, G Valcz ¹, A Kalmár ¹, VÁ Patai ¹, A Schöller ¹, R Wasserkort ³, Z Tulassay ², B Molnár ²

¹2nd Department of Internal Medicine, Semmelweis University, Budapest
²Molecular Medicine Research Unit, Hungarian Academy of Sciences, Budapest
³Epigenomics Inc., Berlin

Abstract

Background: Colorectal cancer (CRC) is one of the frequent cause of cancer-related death worldwide. Present screening tests do not have respective specificity and sensitivity; furthermore the compliance is very low. Detection of DNA methylation is possible from tissue and peripheral blood as well. Every cell type has unique DNA methylation fingerprint. Differences between carcinoma and healthy samples can be detected with the identification of methylated sequence.

Aim: Our aims were to give an overview about septin 9 methylation marker verification and confirmation from peripheral blood and biopsy samples, furthermore compare our results between healthy, adenoma and CRC specimens.

Material and Methods: Biopsy and plasma samples were collected and analyzed from 20 healthy, 20 adenoma and 20 CRC patients. Free DNA was isolated from the plasma and tissue samples and bisulfite conversion was performed. Real-time PCR assay was used for analysis of septin 9 hypermethylation in bisulfite treated DNA samples. Furthermore septin 9 protein expression was detected in healthy, adenoma and CRC samples by immunhistochemistry using septin 9 polyclonal antibody.

Results: In case of plasma samples 16.6% of healthy, 66.6% of adenoma and 87.5% of colorectal cancer samples showed septin 9 hypermethylation. In biopsy samples, detection of septin 9 methylation status was similar, but more obvious. 100% of colorectal cancer tissues showed septin 9 metlylation. Thus septin 9 biomarker has 87.5% sensitivity and 83.4% specificity to detect CRC from peripheral blood. In immunhistochemistry assay septin 9 protein expression was significantly different between healthy (100%), adenoma (35–40%) and CRC samples (5–7%).

Conclusions: Blood based detection of methylated DNA sequence is possible in neoplastic and preneoplastic diseases. Septin 9 methylation marker has been established in peripheral blood and tissue as well. Similar Septin 9 methylation status can be detected from plasma and biopsy samples. In case of septin 9 methylation decreased expression of its protein was detected. Thus this gene can be representing as a colorectal cancer specific biomarker.