Suppression of VEGF transcription in renal cell carcinoma cells using pyrrole-imidazole hairpin polyamides targeting the hypoxia responsive element

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Hypoxia inducible factor (HIF), a master regulator of critical genes for cell survival under hypoxia, is known to be related to tumorigenesis and progression of renal cell carcinoma. N-methylpyrrole (Py)-N-methylimidazole (Im) hairpin polyamides are synthetic organic compounds which recognize and bd to minor groove of specific DNA sequences. We synthesized three Py-Im hairpin polyamides targeting the flanking sequences of hypoxia responsive element (a binding site of HIF) in the promoter region of the vascular endothelial growth factor (VEGF) gene. Effects of the polyamides on HIF-induced transcription was evaluated by luciferase assay using a reporter plasmid containing VEGF promoter. Real time reverse transcriptase polymerase chain reaction and enzyme-linked immunosolvent assay were performed to examine effects of the polyamides on transcription and secretion of VEGF in A498 renal cell carcinoma cells which has a frame shift mutation in the von Hippel-Lindau gene. Combinations of three Py-Im hairpin polyamides suppressed HIF-induced transcription in reporter assays using 293 cells, and successfully suppressed transcription and translation of the VEGF gene in A498 cells. The approach using Py-Im hairpin polyamides may provide a new strategy for the treatment of renal cell carcinoma that is resistant to conventional chemotherapy or irradiation.