Detection of Methylated SEPT9 in Plasma Is a Reliable Screening Method for Both Left- and Right-Sided Colon Cancers

Abstract

BackgroundMethylated Septin 9 (SEPT9) is a sensitive biomarker for colorectal cancer (CRC) from peripheral blood. However, its relationship to cancer localization, guaiac-based fecal occult blood test (gFOBT) and carcinoembryonic antigen (CEA) have not been described.Methodology/Principal FindingsPlasma samples were collected for SEPT9 analysis from patients with no evidence of disease (NED) (n = 92) before colonoscopy and CRC (n = 92) before surgical treatment. DNA was isolated and bisulfite-converted using Epi proColon kit 2.0. Qualitative determination was performed using Epi proColon 2.0 RT-PCR assay. Samples for gFOBT and CEA analysis were collected from NED (n = 17 and 27, respectively) and CRC (n = 22 and 27, respectively). SEPT9 test was positive in 15.2% (14/92) of NED and 95.6% (88/92) of CRC, including 100% (67/67) from stage II to stage IV CRC and 84% (21/25) of stage I CRC when a sample was called positive if 1 out of 3 PCR replicates was positive. In a second analysis (2 out of 3 PCR replicates) specificity improved to 99% (91/92) of NEDs, at a sensitivity of 79.3% (73/92) of SEPT9 positives in CRC. gFOBT was positive in 29.4% (5/17) of NED and 68.2% (15/22) of CRC and elevated CEA levels were detected in 14.8% (4/27) of NED and 51.8% (14/27) of CRC. Both SEPT9 (84.8%) and CEA (85.2%) showed higher specificity than gFOBT (70.6%). SEPT9 was positive in 96.4% (54/56) of left-sided colon cancer (LSCC) cases and 94.4% (34/36) of right-sided colon cancer (RSCC) cases. gFOBT was positive in 83.3% (10/12) of cases with LSCC and 50% (5/10) of cases with RSCC, elevated CEA was detected 60% (9/15) of LSCC and 41.7% (5/12) of RSCC.Conclusions/SignificanceThe high degree of sensitivity and specificity of SEPT9 in plasma makes it a better method to detect CRC than gFOBT and CEA, even for the more difficult to detect RSCC.

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

“…Among the methylated genes in CRC, septin-9 has been highlighted as an ideal candidate biomarker (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). Septin-9 was initially identified in myeloid neoplasia (20).…”

“…It acts as a suppressor gene in numerous cancer types (21,22). In previous years, an increasing number of studies have focused on the investigation of plasma methylated septin-9 for the detection of CRC (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17). Consequently, several types of assay kits regarding methylated septin-9 are being developed and have become commercial products.…”

Screening for Colorectal Cancer Based on the Promoter Methylation Status of the Septin 9 Gene in Plasma Cell Free DNA

“…Test performance (Table 1) was evaluated in a number of case control studies in Europe and China [27,[31][32][33][34]. As outlined in these studies, test sensitivity was reported to range from 73-81% and test specificity was reported to range from 96-99%.…”

Septin 9 hypermethylation contributes to migration and resistance to drug treatments in colon cancer

“…These epigenetic events combined with diseasecausing mutations provide a selective advantage for cancer initiation and progression. Multiple studies have shown that septin 9 gene spanning a region of 219 kb in the genome and encoding different isoforms is epigenetically modified in the promoter region, and can be used as a diagnostic test for CRC [6][7][8].…”