Abstract 3743: Effect of folic acid supplementation on epigenetics and cancer stem cell populations in established colorectal cancer cell lines.

Abstract

Abstract Mandated fortification of folic acid, a B vitamin involved in nucleotide synthesis and DNA CpG methylation, has led to a subsequent increase in blood folate concentration as well as a simultaneous increase in colorectal cancer incidence in North America. Recent findings suggest that a proportion of tumor cells, termed cancer stem cells (CSC), share properties with native stem cells and are vital in the development and perpetuation of tumor metastasis. Both epigenetic DNA modifications as well as the activation of established stem cell signaling pathways are responsible for the activation and maintenance of (CSC). CSC share properties with native stem cells and are vital in the development of primary lesions and the perpetuation of tumor metastasis. We hypothesize that folate, a CpG methylation altering agent, and extracellular microenvironment factors can influence the development and maintenance of CSCs. By isolating and characterizing the CSC fraction in established human colorectal cancer cell lines HCT116, Caco2, and SW480, LS174T and PC7, a subline of DLD-1, we have assessed the effect of folate on CSC signaling pathways and global DNA methylation. Cell lines were grown in suspension and supplemented with specialized stem cell media to promote the growth and expansion of the CSC fraction. Western blot analysis and immunofluorescence were used to characterize the protein expression and nuclear localization of proteins associated with established CSC maintenance pathways, respectively. Global DNA methylation status was assessed using an ELISA-based assay. HCT116 and SW480 show an increased ability to form colonospheres in culture compared to Caco2 and IEC18 (normal rat intestinal cell line). Cells grown in suspension show variable activation of stem cell renewal pathways compared to monolayer. Low folic acid levels led to reduced methylation status and colonosphere yield while high folic acid levels led to increased global methylation and an increased in colonosphere yield. Thus, altered folic acid exposure in vitro can influence the methylation status and CSC self-renewal ability of human colorectal cancer cells. The relationship between folic acid and cancer stem cell maintenance may be an important factor in the apparent duel modulatory effect of folic acid on colorectal cancer and warrants further investigation. Citation Format: Nathan Farias, Brenda Coomber. Effect of folic acid supplementation on epigenetics and cancer stem cell populations in established colorectal cancer cell lines. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3743. doi:10.1158/1538-7445.AM2013-3743