The Influence of Methylated Septin 9 Gene on RNA and Protein Level in Colorectal Cancer

Abstract

Colorectal cancer is one of the leading death causes in the world. Specificity and sensitivity of the present screening methods are unsuitable and their compliance is too low. Nowadays the most effective method is the colonoscopy, because it gives not only macroscopic diagnosis but therapeutic possibility as well, however the compliance of the patients is very low. Hence development of new diagnostic methods is needed. Altered expression of septin 9 was found in several tumor types including colorectal cancer. The aim of this study was to detect the methylation related mRNA and protein expression changes of septin 9 in colorectal adenoma-dysplasia-carcinoma sequence and to analyze its reversibility by demethylation treatment. Septin 9 protein expression showed significant difference between normal and colorectal cancer (CRC) samples (p < 0,001). According to biopsy microarray results, septin 9 mRNA expression decreased in the progression of colon neoplastic disease (p < 0,001). In laser microdissected epithelial cells, septin 9 significantly underexpressed in CRC compared to healthy controls (p < 0,001). The expression of septin9_v1 region was higher in the healthy samples, while septin9_v2, v4, v4*, v5 overexpression were detected in cancer epithelial cells compared to normal. The septin 9 mRNA and protein levels of HT29 cells increased after demethylation treatment. The increasing methylation of septin 9 gene during colorectal adenoma-dysplasia-carcinoma sequence progression is reflected in the decreasing mRNA and protein expression, especially in the epithelium. These changes can be reversed by demethylation agents converting this screening marker gene into therapeutic target.

A pooled analysis of the diagnostic efficacy of plasmic methylated septin-9 as a novel biomarker for colorectal cancer

“…1 shows the procedure of article filtration based on the PRISMA statement: In total, 291 citations were obtained from the online databases according to the specified criteria, of which 276 records were excluded after a careful review of the title and abstracts. The following 15 eligible studies then received full text evaluation and 1 of them was eliminated due to lack of relevance (26). Finally, 14 cohorts comprising 23 single studies were enrolled for the meta-analysis (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17).…”

Septin roles in tumorigenesis

“…To correlate the methylation profile of SEPT9 with its expression Toth et al measured mRNA and protein levels in the different stages of colorectal cancer (adenoma-dysplasiacarcinoma, Toth et al, 2011). SEPT9 protein levels were found to decrease with increasing stages of tumorigenesis, corresponding to a possible increase in methylation levels.…”

“…Moreover, demethylation of the HT29 colorectal adenocarcinoma grade II cell line with 5-aza-2-deoxycytidine (a DNA de-methylating agent) resulted in increased SEPT9 mRNA and protein expression. This suggests that the increasing methylation of SEPT9 during colorectal cancer progression is a mechanism responsible for decreasing mRNA and protein expression and its ability to be reversed by DNA methylation inhibitors makes SEPT9 an ideal therapeutic target (Toth et al, 2011).…”

Epi proColon®: Use of a Non-Invasive SEPT9 Gene Methylation Blood Test for Colorectal Cancer Screening: A National Laboratory Experience

“…Epigenetic silencing of the SEPT9 gene by promoter methylation in cell-free plasma has been shown to be a biomarker for CRC [12,16,17]. Using high-sensitivity Real-Time PCR methods, hypermethylated SEPT9 DNA signatures can be detected in cellfree plasma [12,[19][20][21][22][23][24][25][26][27]. As an early event and hallmark of human cancers, aberrant DNA methylation biomarkers have clinical roles in screening, diagnosis, prognosis and therapeutic response [11,28].…”