PhD Scientific Days 2021

PO_I_P: Pathology and Oncology I. Posters

Analyzing the Effect of Folic Acid on Genetic and Epigenetic Alterations

Text of the abstract

Vitamin B9, also known as folate, is involved in several biochemical reactions such as amino acid and DNA synthesis along with DNA methylation; therefore, it takes part in genetic as well as epigenetic regulation. Concerning tumor development and progression, its dual role is actively investigated.
Our aim was to analyze the effect of folic acid (synthetic folate) depletion and treatment on two human colorectal cancer cell lines (HT-29 and SW480). Additionally, we aimed to compare the gene expression alterations affected by these conditions between SW480 cell line and SCID mice subcutaneously implanted with SW480 cells.
Cells were treated with folic acid (FA) for 72 hours in two different concentrations (100; 10,000 ng/mL) or kept in FA-free media. SRB assay and FACS were used for proliferation and cell cycle determination. Global DNA methylation pattern was studied by bisulfite pyrosequencing of LINE-1 retrotransposons. DNA integrity analysis was performed with immunostaining and comet assay. After treating SCID mice with 20 mg/kg FA, gene expression changes were detected using microarray chips.
According to the applied concentration, alterations in cell proliferation (HT-29(100): +19.89% and HT-29(10,000): -5.60%; SW480(100): +1.34% and SW480(10,000): +7.74% compared to non-treated cells) and apoptosis number (HT-29(0): 45.65%; HT-29(100): 52.89%; HT-29(10,000): 34.83% and SW480(0): 8.34%; SW480(100): 15.67%; SW480(10,000): 7.68%) were observed. We also noticed the elevation of DNA methylation level specific to certain LINE-1 CpG sites in answer to the treatment. According to DNA integrity analyses, the activation of DNA repair processes for FA supplementation was presumed in the HT-29 cell line. Significant expression changes of cancer progression-related genes (160 transcript IDs) were detected comparing treated or non-treated SW480 cells and SCID mice.
Based on our results, FA influences cell turnover rate and global DNA methylation pattern of the two colorectal cancer cell lines; additionally, it might induce DNA repair in HT-29 cells. FA supplementation appears to have a similar effect on cancer progression-related genes in both in vitro and in vivo experiments. Thereby we can conclude that FA affects cancer cells in diverse ways. A comprehensive understanding of these processes may contribute to the development of new cancer therapy methods.

University and Doctoral School

Semmelweis University, Károly Rácz Doctoral School of Clinical Medicine