Kaempferol suppresses cell metastasis via inhibition of the ERK-p38-JNK and AP-1 signaling pathways in U-2 OS human osteosarcoma cells

Abstract

Kaempferol is a natural flavonoid that possesses anti-proliferative and apoptosis-inducing activities in several cancer cell lines. In the present study, we investigated the anti-metastatic activity of kaempferol and its molecular mechanism(s) of action in human osteosarcoma cells. Kaempferol displayed inhibitory effects on the invasion and adhesion of U-2 osteosarcoma (OS) cells in a concentration-dependent manner by Matrigel Transwell assay and cell adhesion assay. Kaempferol also inhibited the migration of U-2 OS cells in a concentration-dependent manner at different treatment time points by wound-healing assay. Additional experiments showed that kaempferol treatment reduced the enzymatic activities and protein levels of matrix metalloproteinase (MMP)-2, MMP-9 and urokinase plasminogen activator (uPA) by gelatin and casein-plasminogen zymography assays and western blot analyses. Kaempferol also downregulated the mRNA levels of MMP-2 and MMP-9 by quantitative PCR analyses. Furthermore, kaempferol was able to reduce the protein phosphorylation of ERK, p38 and JNK by western blotting. By electrophoretic mobility-shift assay (EMSA), we demonstrated that kaempferol decreased the DNA binding activity of AP-1, an action likely to result in the reduced expression of MMP-2, MMP-9 and uPA. Collectively, our data showed that kaempferol attenuated the MAPK signaling pathways including ERK, JNK and p38 and resulted in the decreased DNA binding ability of AP-1, and hence, the downregulation in the expression and enzymatic activities of MMP-2, MMP-9 and uPA, contributing to the inhibition of metastasis of U-2 OS cells. Our results suggest a potential role of kaempferol in the therapy of tumor metastasis of OS.

Kaempferol induces ATM/p53-mediated death receptor and mitochondrial apoptosis in human umbilical vein endothelial cells

“…3B) in HUVECs cells. It is well known that caspase-3 is a key mediator of cell apoptosis (13,14). Next, we used caspase-3 immunofluorescence staining and confocal laser scanning microscopy to observe the caspase-3 protein expression.…”

“…Our previous study demonstrated that kaempferol-induced apoptosis in human osteosarcoma cells is mediated through endoplasmic reticulum stress and mitochondria-dependent signaling (13). Kaempferol also induces autophagy by AMPK and AKT signaling and causes G2/M phase arrest via downregulation of CDK1/cyclin B in human hepatocarcinoma cells (14). However, there is no report addressing the possible anti-angiogenetic mechanism of kaempferol.…”

<i>Citrus</i> Flavonoids and Human Cancers

“…Park et al [109] reported that Citrus flavonoids isolated from Korean Citrus aurantium L have anti-invasive effect through the inhibition of MMP-2 expression in A549 cells in a dosedependent manner. Chen et al [110] investigated the antimetastatic activity of kaempferol and its molecular mechanism of action in human U-2 osteosarcoma (U-2 OS) cells. They found that kaempferol influenced the expression and enzymatic activities of MMP-2, MMP-9 and urokinase plasminogen activator (uPA) through attenuating the MAPK signaling pathways including ERK, JNK and p38 by decreasing DNA binding ability of AP-1.…”

Naringenin modulates the metastasis of human prostate cancer cells by down regulating the matrix metalloproteinases -2/-9 via ROS/ERK1/2 pathways

“…Previous reports have demonstrated the antioxidant capacities of various dietary flavonoids. Kaempferol has been shown to have diverse biological and pharmacological effects such as antioxidant activity and anticancer-related properties (Huang et al, 2014;Kang et al, 2010;Chen et al, 2013).…”