Neuropilin-1 is upregulated in hepatocellular carcinoma and contributes to tumour growth and vascular remodelling.

Background & Aims: Neuropilin-1 (NRP1) is a transmembrane co-receptor for semaphorins and heparin-binding pro-angiogenic cytokines, principally members of the vascular endothelial growth factor family. Recent studies revealed an important role of NRP1 in angiogenesis and malignant progression of many cancers. The role of NRP1 in the development of hepatocellular carcinoma (HCC) is not completely understood.

Methods: We used human tissue microarrays and a mouse transgenic model of HCC to establish the spatio-temporal patterns of NRP1 expression in HCC. To evaluate the therapeutic potential of targeting NRP1 in HCC, we treated HCC mice with peptide N, an NRP1 binding recombinant protein and competitive inhibitor of the VEGF-A(165)/NRP1 interaction.

Results: We demonstrate that NRP1 is expressed in hepatic endothelial cells of both human healthy biopsies and in HCC samples, but not in normal hepatocytes. We found that increased NRP1 expression in human tumour hepatocytes is significantly associated with primary HCC. Using RT-PCR, Western blot and immunofluorescence analysis we show that NRP1 expression in the liver of transgenic HCC mice is increased with disease progression, in both vascular and tumour compartments. Blocking NRP1 function with peptide N leads to the inhibition of vascular remodelling and tumour liver growth in HCC mice.

Conclusions: Our results indicate a specific role of NRP1 in HCC growth and vascular remodelling and highlight the possibility of therapeutically targeting NRP1 for the treatment of HCC.