OBJECTIVE: This study was designed to investigate the therapeutic and anti-metastatic potential of the two newly obtained anti-nNav1.5 antibodies, polyclonal anti-nNav1.5 (pAb-nNav1.5) and monoclonal anti-nNav1.5 (mAb-nNav1.5), on breast cancer invasion and metastasis.

METHODS: MDA-MB-231 and 4T1 cells were used as in vitro models to study the effect of pAb-nNav1.5 (59.2 µg/ml) and mAb-nNav1.5 (10 µg/ml) (24 hours treatment) on cell invasion. 4T1-induced mammary tumours in BALB/c female mice were used as an in vivo model to study the effect of a single dose of intravenous pAb-nNav1.5 (1 mg/ml) and mAb-nNav1.5 (1 mg/ml) on the occurrence of metastasis. Real-time PCR and immunofluorescence staining were conducted to assess the effect of antibody treatment on nNav1.5 mRNA and protein expression, respectively. The animals' body weight, organs, lesions, and tumour mass were also measured and compared.

RESULTS: pAb-nNav1.5 and mAb-nNav1.5 treatments effectively suppressed the invasion of MDA-MB-231 and 4T1 cells in the 3D spheroid invasion assay. Both antibodies significantly reduced nNav1.5 gene and protein expression in these cell lines. Treatment with pAb-nNav1.5 and mAb-nNav1.5 successfully reduced mammary tumour tissue size and mass and prevented lesions in vital organs of the mammary tumour animal model whilst maintaining the animal's healthy weight. mRNA expression of nNav1.5 in mammary tumour tissues was only reduced by mAb-nNav1.5.

METHODS: Blood specimens were obtained from 92 malignant, 16 benign breast cancer patients and 23 healthy controls. The serum concentrations of sPD-L1 were assessed by enzyme-linked immunosorbent assay (ELISA).