Angiogenesis is a potential target for cancer therapy. We identified a novel signaling pathway that sustains angiogenesis and progression in colorectal cancer (CRC). This pathway is triggered by β 1 integrin-mediated adhesion and leads to VEGF-A secretion. The effect is modulated by the human ether-à-go-go related gene 1 (Herg1) K + channel. Herg1 recruits and activates PI3K and Akt. This in turn increases the Hypoxia Inducible Factor (HIF)-dependent transcription of VEGF-A and other tumour progression genes. This signaling pathway has novel features in that the integrin-and Herg1-dependent activation of HIF (i) is triggered in normoxia, especially after CRC cells have experienced a hypoxic stage, (ii) involves NF-kB and (iii) is counteracted by an active p53. Blocking Herg1 switches this pathway off also in vivo, by inhibiting cell growth, angiogenesis and metastatic spread. This suggests that non-cardiotoxic anti-Herg1 drugs might be a fruitful therapeutic strategy to prevent the failure of anti-VEGF therapy.
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