Finding
This difference in the method of proving apoptosis might be due to different mechanism of induced cell death by phosphorylated ganciclovir.
Paper
Abstract 1517: Wnt signaling pathway seems a better target than k-ras pathway for colon cancer specific suicide gene therapy
Abstract
As Wnt and K-ras are two most important signaling pathways activated in colon cancer, exploiting them for colon cancer specific gene therapy seems an attractive biological approach for therapy of colon cancer. Our aim was inserting specific promoters downstream to these pathways upstream of suicide genes. Therefore we investigated promoters downstream to these signaling pathways in order to insert them upstream of suicide genes. These promoters should be specifically upregulated by these pathways. They should have been proved to be inactive in normal cells of the body. These promoters should also be short enough to be inserted upstream of a therapeutic gene in a gene therapy construct. After investigating we found out Fibroblast Growth factor 18 (FGF18) and Urokinase Plasminogen Activator Receptor (UPAR) promoters which met the above mentioned criteria and seemed to be the most plausible promoters downstream to Wnt and K-ras signaling pathways. We inserted the most important parts of these promoters upstream of β-Gal as reporter and thymidine kinase as suicide genes. The activity of these promoters in two distinct colon cancer cell lines (HCT116 and SW480) and normal colon cells was studied. It was showed that FGF18 and UPAR promoter activity in HCT116 cell line was 0.25 and 0.187 times in comparison to CMV promoter while in SW480 this ratio was 0.09 and 0.02. Neither of promoters was active in normal colon cells. After applying the specific suicidal constructs in colon cancer cells, it was showed that both suicidal constructs reduced the viability of HCT116 in the presence of 20µg/ml of ganciclovir while in SW480 UPAR and FGF18 promoters reduced the viability in the presence of 40µg/ml and 20µg/ml ganciclovir respectively. The positive control suicidal construct induced significant reduction in the viability of both cell lines in the presence of 20µg/ml ganciclovir. The apoptosis induced by these suicidal constructs was also proved by M30cytodeath antibody in HCT116 and Annexin-PI in SW480. This difference in the method of proving apoptosis might be due to different mechanism of induced cell death by phosphorylated ganciclovir. These experiments showed that exploiting specific promoters downstream to activated signaling pathways in cancerous cells would be a good strategy for specific expression of therapeutic genes in cancerous cells. Also in colon cancer exploiting universal pathways such as wnt might be a better investment for this approach. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1517.
Authors
L. Teimoori-Toolabi, K. Azadmanesh, Sirous Zeianli
Journal
Cancer Research