Abstract A19: Silencing LEF1 decreases the resistance of colorectal cancer cell lines to 5-FU as common chemotherapeutic drug

Abstract

Abstract Wnt signaling pathway is assumed to be the most important pathway activated in colorectal cancer. As this pathway in addition to Notch and hedgehog signaling pathway is responsible for the maintenance of stem cells in the population of cancerous cells, it could be predicted that by silencing this pathway the resistance of cancerous cells to chemotherapeutic drugs would be decreased. In this regard we tried to silence LEF1 as an important component of this pathway in two colorectal cancer cell lines and see the response of transfected cells to 5-flurouracil. Oligonucleotide for silencing LEF1 was constructed and inserted into pSilencer Neo2.1 (Invitrogen). Thereafter these constructed were stably transfected to HCT116 and SW480 as colorectal cancer cell lines after treating the transfected cells with G418 for 21 days. Response of these cells to 5-flurouracil as a common chemotherapeutic drug was studied by MTT proliferation assay. The expression of LEF1 in transfected and non-transfected cells was also studied by Quantitative PCR. Cell cycle analysis was done by staining the cells with PI and analyzing them by flowcytometry instrument. While the expression of LEF1 in SW480 transfected with pSilencer-antiLEF1 reduced to 0.004 in comparison to non-transfected cells in HCT116 cells transfected with pSilencer-anti LEF1 this value was 0.000002 in comparison to non-transfected cells. Whereas the LC50 of 5-Flurouracil on non-transfected HCT116 and SW480 for 5-FU were 0.55 ng/µl and 1.45 ng/µl respectively. These values in transfected cells reduced to 0.18 and 0.1 ng/µl respectively. The percentages of proliferating cells (G2+S) stably transfected cells reduced to 30% and 32% in comparison to 39% and 45% in SW480 and HCT116 cell lines respectively. These findings showed that silencing LEF1 as a main component of wnt signaling pathway sensitizes HCT116 and SW480 cells to 5-flurouracil. The difference between sensitizing strength may be due to mutations in other components of wnt signaling pathway or mutations in other genes like p53 and k-ras which is dissimilar between HCT116 and SW480 cells. This modality can be considered as sensitizing agents adjuvant to other chemotherapeutic drugs like 5-FU. Note: This abstract was not presented at the conference. Citation Format: Ladan Teimoori-Toolabi, Elham Fakhr, Fatemeh Zare. Silencing LEF1 decreases the resistance of colorectal cancer cell lines to 5-FU as common chemotherapeutic drug. [abstract]. In: Proceedings of the AACR Special Conference on Colorectal Cancer: From Initiation to Outcomes; 2016 Sep 17-20; Tampa, FL. Philadelphia (PA): AACR; Cancer Res 2017;77(3 Suppl):Abstract nr A19.