Identification of a new anti-invasive low molecular weight compound
Tuesday, 23 June 2009- E-cadherin (CDH1) is an essential cell adhesion molecule that is downregulated during progression of, amongst others, bladder and prostate cancer. Impaired E-cadherin function often results from transcriptional silencing.
Three E-boxes within the CDH1 gene promoter play a crucial role in the binding of transcriptional repressors of E-cadherin. Interestingly, they are also found in other genes that are coordinately downregulated during tumour cell invasion. These E-boxes formed the basis for establishing a cell-based model for high throughput low molecular weight (LMW) compound screening to identify lead compounds with anti-invasion properties.
A group of Dutch researchers led by O. van Hooij conducted a study focusing on the identification of a new anti-invasive low molecular weight compound. They presented their findings at the Prostate Cancer Transitional Research in Europe Meeting held in Amsterdam, the Netherlands.
In their study the core element of the CDH1 promoter, containing the three E-boxes, was cloned in an expression vector to drive firefly luciferase expression together with the HSV-TK promoter driving Renilla luciferase expression as an internal control. The TSU-pr1 cancer cell line was stably transfected with this reporter construct.
For functional invasion assays, four cell lines were transfected with a constitutive CMV-luciferase reporter construct. Tumour cell invasion was determined in a typical transwell system, measuring luciferase activity of the invasive cell fraction.
The results showed that in the first round of screening 30,397 LMW compounds, 24 compounds were found to induce luciferase expression more than two-fold. A secondary library of LMW compounds with chemical structures similar to the positive compounds from the first screening was composed (n=12,966). The secondary screening yielded 18 positive compounds.
Finally, screening of a tertiary library (n=634) resulted in 32 positive ‘hits’. Nine of these positive compounds inhibited tumour cell invasion more than 25%, and one of these also showed dose-dependent anti-invasion activity (>40%). This lead compound now will be tested for anti-tumour invasion activity in vivo.
"We have identified a novel lead compound that most likely interferes with the binding of transcriptional repressors to the CDH1 E-box elements," wrote Van Hooij. "This compound re-activates the expression of CDH1 and other genes that are necessary to maintain epithelial integrity, and hence, this compound potentially may prevent invasion of tumour cells."
Source: O. van Hooij, C.F.J. Jansen, et al., "Identification of a new anti-invasive low molecular weight compound," Radboud University Nijmegen Medical Centre, Department of Urology, Nijmegen, The Netherlands; SPECS Compound Handling, Delft, The Netherlands; Submitted Abstract, Prostate Cancer Transitional Research in Europe Meeting, June 22-23, 2009, Amsterdam, The Netherlands.