METHODS: Reverse transcription-quantitative PCR (RT-qPCR) was used to detect miR-455-5p expression in breast cancer tissues and cell lines. CCK8 and Transwell assays were conducted to assess the effects of miR-455-5p on breast cancer line proliferation, migration, and invasion. SOCS3 expression level in breast cancer tissues and cell lines was determined by qPCR and western blotting. The targeting relationship between miR-455-5p and SOCS3 was determined by dual luciferase reporter gene assay in different breast cancer cell lines. Finally, the upstream and downstream regulatory association between miR-455-5p and SOCS3 was confirmed in breast cancer cells by CCK8, western blot, and Transwell assays.
RESULTS: MiR-455-5p expression was up-regulated in breast cancer tissues; miR-455-5p regulates TNBC proliferation, migration, and invasion of TNBC. SOCS3 was the direct target of miR-455-5p and was down-regulated in breast cancer. Interference with SOCS3 reversed the inhibitory effect of the miR-455-5p inhibitor on breast cancer cells' malignant potential.
CONCLUSION: MiR-455-5p promotes breast cancer progression by targeting the SOCS3 pathway and may be a potential therapeutic target for breast cancer.
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.
CONCLUSION: Overall, this work verifies the uniqueness of targeting nNav1.5 in breast cancer invasion and metastasis prevention, but more importantly, humanised versions of mAb-nNav1.5 may be valuable passive immunotherapeutic agents to target nNav1.5 in breast cancer.