Abstract A17: Methylation profile of SEPT9, NDRG4, p16 genes in colorectal cancer

Background: Colorectal cancer (CRC) is the third most common cancer in Brazil, where it appears as the fifth most deadly cancer. Brazilian National Cancer Institute estimates for the year of 2016 in Brazil 16,660 newly diagnosed cases of CRC in men and 17,620 in women. There is evidence that the incidence and mortality rates can be reduced through the detection of precursor lesions and early cancer in the context of CRC screening. Aberrant hypermethylation of cancer-related genes has emerged as a promising strategy for the molecular CRC screening. However, the methylation profile of colorectal cancer of the Brazilian population has limited information about its characterization and frequency. Objective: To investigate the frequency of DNA methylation in the promoter region of tumor suppressor genes SEPT9, NDRG4, and CDKN2A (p16) in sporadic CRCs of Brazilian patients. Methods: Retrospective molecular analysis included 57 adult patients with CRC in different clinical stages attended at the Barretos Cancer Hospital. Demographic, clinical, and tumor-related characteristics were obtained from medical records. DNA was extracted from fresh-frozen tumor tissues. Levels of DNA methylation were determined by quantitative pyrosequencing. Results: The mean ± SD age of the 57 patients9 analysis was 64.40 ±14 years; 56.14% (32/57) were males. Almost all tumors (56/57; 98.24%) were located in the left side of the colon, from descending colon to rectum. Regarding stage, 3/57 (5.26%) were stage 0, 15/57 (26.31 %) stage I, 27/57 (47.36%) stage II, 10/57 (17.54%) stage III, and 2/57 (3.53%) stage IV tumors. Among 57 analyzed, 52/57 (91.22%) were methylated for SEPT9, 42/57 (73.68%) for NDRG4, and 15/57 (26.31%) for CDKN2A. In conclusion, in our Brazilian case series, the gene SEPT9 and NDGR4 showed high frequency of methylation CRC tissues, similar with results found in other populations. Citation Format: Thais Sobanski, Lidia Arantes, Wellington dos Santos, Ronilson Duraes, Marcus Matsushita, Rui Manuel Reis, Denise Peixoto Guimaraes. Methylation profile of SEPT9, NDRG4, p16 genes in colorectal cancer [abstract]. In: Proceedings of the AACR International Conference held in cooperation with the Latin American Cooperative Oncology Group (LACOG) on Translational Cancer Medicine; May 4-6, 2017; Sao Paulo, Brazil. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(1_Suppl):Abstract nr A17.