Angiopoietin-like 4 induces head and neck squamous cell carcinoma cell migration through the NRP1/ABL1/PXN pathway

Objectives: The molecular mechanisms whereby angiopoietin-like 4 (ANGPTL4), a pluripotent protein implicated in cancer development, contributes to head and neck squamous cell carcinoma (HNSCC) growth and dissemi-nation are unclear.Materials and Methods: We investigated ANGPTL4 expression in human normal oral keratinocytes (NOKs), dysplastic oral keratinocytes (DOKs), oral leukoplakia cells (LEUK1), and HNSCC cell lines, as well as in tissue biopsies from patients with oral dysplasia, and primary and metastatic HNSCC. We further examined the contribution of ANGPTL4 cancer progression in an HNSCC orthotopic floor-of mouth tumor model and the signaling pathways linking ANGPTL4 to cancer cell migrationResults: ANGPTL4 expression was upregulated in premalignant DOKs and HNSCC cell lines compared to NOKs and was increased in tissue biopsies from patients with oral dysplasia, as well as in primary and metastatic HNSCC. We also observed that downregulation of ANGPTL4 expression inhibited primary and metastatic cancer growth in an HNSCC orthotopic tumor model. Interestingly, ANGPTL4 binding to the neuropilin1 (NRP1) re-ceptor led to phosphorylation of the focal adhesion protein, paxillin (PXN), and tumor cell migration; this was dependent on the tyrosine kinase ABL1. Treatment with the ABL1 inhibitor, dasatinib and small interfering RNA silencing of NRP1 or ABL1 expression blocked PXN phosphorylation and tumor cell migration.Conclusion: Our findings suggest an early, sustained, and angiogenesis-independent autocrine role for ANGPTL4 in HNSCC progression and expose ANGPTL4/NRP1/ABL1/PXN as an early molecular marker and vulnerable target for the prevention of HNSCC growth and metastasis.

Automated summary

This study investigated the molecular mechanisms of angiopoietin-like 4 (ANGPTL4) in the growth and dissemination of head and neck squamous cell carcinoma (HNSCC). It was found that ANGPTL4 was upregulated in premalignant cells and HNSCC cell lines, as well as tissue samples from patients with oral dysplasia and HNSCC. Furthermore, ANGPTL4 was found to promote tumor cell migration through its binding to neuropilin1 (NRP1) and subsequent phosphorylation of focal adhesion protein, paxillin (PXN), in a pathway dependent on ABL1 tyrosine kinase. Inhibition of ABL1 or NRP1 expression blocked this pathway and inhibited tumor cell migration.