Selection by phage display of nanobodies directed against hypoxia inducible factor-1α (HIF-1α)

Hypoxia, which promotes tumor invasion and metastasis, is a common phenomenon in solid tumors. Hypoxia generally leads to a higher expression level of hypoxia inducible factor-1 (HIF-1) in tumors (cells) relative to normal tissues (cells). Given the unique expression of HIF-1α in human cancers and its vital importance in mediating hypoxic adaptation, we have identified 20 different HIF-1α-specific nanobodies by using a llama-derived nonimmune phage display library. PAS-B domain of HIF-1α (HIF-1α-PAS-B) has been used as an antigen. Nanobody (VHH16) was selected from these 20 nanobodies by phage enzyme-linked immunosorbent assay. The preliminary analysis of biological activity demonstrates that VHH16 can specifically bind to HIF-1α with high affinity. VHH16 is the first nanobody that specifically binds to HIF-1α-PAS-B as well. We suggest here that VHH16 is useful in disease diagnosis and also has potential in medical applications.