Decoy molecules based on PNA-DNA chimeras and targeting Sp1 transcription factors inhibit the activity of urokinase-type plasminogen activator receptor (uPAR) promoter

The expression levels of urokinase-type plasminogen activator receptor (uPAR) are strongly correlated with metastatic potential in human cancer cell lines of melanoma, breast, lung, and colon. Therefore, targeting of uPAR could have practical implications in the treatment of neoplastic diseases. Because the expression of uPAR is regulated at the level of transcription in part by Sp1, we designed and tested transcription factors decoy molecules targeting Sp1 with the aim of inhibiting uPAR gene expression. The main objective of the present study was to determine whether decoy molecules based on peptide nucleic acids (PNA)-DNA chimeras mimicking Sp1 binding sites might be proposed as useful reagents to alter expression of Sp1-regulated genes involved in tumor invasion and metastasis. The results obtained firmly indicate that Sp1 binding molecules based on PNA-DNA-PNA chimeras are powerful decoys, as they efficiently inhibit the interactions between Sp1 and the uPAR promoter elements. Experiments performed on hepatoma HepG2 cells transfected with a plasmid containing the firefly luciferase gene reporter under the control of the human uPAR promoter demonstrate that PNA-DNA-PNA-based decoy molecules are potent inhibitors of the transcriptional activity of the uPAR promoter. Our results suggest that these molecules warrant attention for the design of novel antimetastatic drugs.