Panax notoginseng saponins (PNS) inhibits breast cancer metastasis

Panax notoginseng (Burkill) F.H. Chen (Araliaceae) has been extensively used as a therapeutic agent to treat a variety of diseases. Panax notoginseng saponins (PNS) consist of major therapeutically active components of Panax notoginseng. PNS inhibit the growth of a variety of tumor cells in vitro and in vivo. The aim of the study is to investigate the effects and underlying mechanisms of PNS on breast cancer metastasis.

4T1 cell, a highly metastatic mouse breast carcinoma cell line, was utilized for in vitro and in vivo assays. In vitro assays were first performed to examine the effects of PNS on 4T1 cell viability, migration and invasion, respectively. Real-time PCR analyses were also performed to examine the effects of PNS on the expression of genes associated with tumor metastasis. The effect of PNS on 4T1 tumor cell metastasis was further assessed in spontaneous and experimental metastasis models in vivo.

PNS treatment exhibited a dose-dependent effect on impairing 4T1 cell viability in vitro. However, when examined at a lower dose that did not affect cell viability, the migration and invasion of 4T1 cell was remarkably inhibited in vitro. Meanwhile, PNS treatment led to upregulated expression of genes known to inhibit metastasis and downregulated expression of genes promoting metastasis in cultured 4T1 cells. These results suggested a selective effect of PNS on 4T1 migration and invasion. This hypothesis was further addressed in 4T1 metastasis models in vivo. The results showed that the lung metastasis was significantly inhibited by PNS treatment in both spontaneous and experimental metastasis models.

Taken together, our results demonstrated an inhibitory effect of PNS on 4T1 tumor metastasis, warranting further evaluation of PNS as a therapeutic agent for treating breast cancer metastasis.