CaMKII Inhibitor KN-62 Blunts Tumor Response to Hypoxia by Inhibiting HIF-1Ձ in Hepatoma Cells

CaMKII Inhibitor KN-62 Blunts Tumor Response to Hypoxia by Inhibiting HIF-1Ձ in Hepatoma Cells

In rapidly growing tumors, hypoxia commonly develops due to the imbalance between O₂ con</SUB>sumption and supply. Hypoxia Inducible Factor (HIF)-1Ձ is a transcription factor responsible for tumor growth and angiogenesis in the hypoxic microenvironment; thus, its inhibition is regarded as a promising strategy for cancer therapy. Given that CamKII or PARP inhibitors are emerging anticancer agents, we investigated if they have the potential to be developed as new HIF-1Ձ-targeting drugs. When treating various cancer cells with the inhibitors, we found that a CamKII inhibitor, KN-62, effectively suppressed HIF-1Ձ specifically in hepatoma cells. To examine the effect of KN-62 on HIF-1Ձ- driven gene expression, we analyzed the EPO-enhancer reporter activity and mRNA levels of HIF-1Ձ downstream genes, such as EPO, LOX and CA9. Both the reporter activity and the mRNA expression were repressed by KN-62. We also found that KN-62 suppressed HIF-1Ձ by impairing synthesis of HIF-1Ձ protein. Based on these results, we propose that KN-62 is a candidate as a HIF-1Ձ-targeting anticancer agent.