Icariside I reduces breast cancer proliferation, apoptosis, invasion, and metastasis probably through inhibiting IL-6/STAT3 signaling pathway

Abstract

Abstract Objectives Breast cancer is a common malignancy in women. More than 90% of breast cancer deaths are caused by metastasis. Epimedii Folium (EF) is a commonly used herb with anti-tumor benefits, but its underlying mechanisms and active components for breast cancer prevention are little understood. This study assessed the therapeutic role of Icariside I (ICS I) in Epimedium flavonoids (EF) on lung metastasis of breast cancer, including the underlying mechanism. Methods Western blot, RT-qPCR, wound healing assay, colony formation assay, and flow cytometry were used to investigate the inhibition of breast cancer cells growth and migration by EF and ICS I through disrupting the IL-6/STAT3 pathway. Combined with 4T1 breast cancer model in mice, Western blot, RT-qPCR, Hematoxylin and Eosin staining, immunohistochemistry were used to evaluate the therapeutic role of ICS I in proliferation, apoptosis, invasion, and metastasis of breast cancer. Key findings EF can inhibit STAT3 phosphorylation and reduce the colony formation and migration of breast cancer cells. Detecting the active ingredients in EF, we found ICS I can reduce the activation of STAT3 in 4T1 breast cancer cells, impair colony formation and migration. Moreover, ICS I induced cells G1 phase arrest and modulated Cyclin D1, CDK4, bcl-2, and bax to inhibit proliferation and survival of breast cancer cells. Similarly, the in vivo studies demonstrated that ICS I significantly suppressed tumor development and lung metastasis in the 4T1 mouse model. Tumor cells in vehicle group were arranged in a spoke-like pattern with obvious heterogeneity, and multinucleated tumor giant cells were seen. But, the tumor cells in the ICS I group were disorganized and necrotic lysis was seen in some areas. In ICS I-treated group, tumors’ STAT3 phosphorylation level, IL-6, Cyclin D1, CDK4, bcl-2, and vimentin expression were downregulated, bax and cleaved caspase 3 expression were upregulated. In the lung tissue, we could find less metastasis of breast cancer cells and less lung injury in the ICS I group. Besides, the expression of metastasis-related genes MMP9 and vimentin was decreased in the lung tissue of ICS I group. Conclusions These findings suggest that ICS I can inhibit breast cancer proliferation, apoptosis, invasion and metastasis probably via targeting IL-6/STAT3 pathway. Therefore, ICS I has the potential to become an innovative therapeutic candidate to breast cancer prevention and treatment.