Original Article
Low frequency ultrasound combined with baicalein can reduced the invasive capacity of breast cancer cells by down regulating the expression of MMP-2, MMP-9, and u-PA
Abstract
Background: Over the past three decades, a large number of patients have died owing to breast cancer metastasis and recurrence. Therefore, there is an urgent need to develop effective and comprehensive strategies for the treatment of breast cancer. Earlier studies have demonstrated that low frequency ultrasound and baicalein can arrest the invasive activity of breast cancer cells and inhibit the migration and metastasis of breast cancer. However, the exact mechanism of action of this combination remains elusive. Furthermore, the inhibitory effect of the combination treatment with low frequency ultrasound and baicalein on breast cancer has not been reported.
Methods: In this study, human breast cancer cell line MDA-MB-231 was cultured and subjected to one of the following four treatment: low frequency ultrasound, baicalein, combination of the two, or no treatment. Cells in the low frequency group were irradiated with ultrasound for 5 min at a frequency of 840 kHz, 0.75 W/cm2. Cells in the baicalein group were treated with baicalein for 24 h at a concentration of 150 μmol/L. In the combination group, cells were treated with both low frequency ultrasound and baicalein. Cells receiving no treatment were designated as the control group. Invasive capacity of cells in the four groups was examined by transwell assay. matrix metalloproteinase 2 (MMP-2), MMP-9, and urokinase type plasminogen activator (u-PA) mRNA and protein levels were examined using Real-time PCR and Western blotting, respectively.
Results: The invasive capacity of cells in the low frequency group, baicalein group and the combination group was significantly reduced by 21.6%±1.68%, 31.9%±2.19% and 51.6%±2.01%, respectively. The expression levels of both mRNA and protein of MMP-2, MMP-9, and u-PA were significantly decreased in all three treatment groups, compared to that in the control group. The decline in the expression of MMP-2, MMP-9 and u-PA was highest in the combination group at both mRNA and protein levels.
Conclusions: Low frequency ultrasound combined with baicalein can effectively reduce the invasive capacity of breast cancer, probably by downregulating the expression of MMP-2, MMP-9, and u-PA.
Methods: In this study, human breast cancer cell line MDA-MB-231 was cultured and subjected to one of the following four treatment: low frequency ultrasound, baicalein, combination of the two, or no treatment. Cells in the low frequency group were irradiated with ultrasound for 5 min at a frequency of 840 kHz, 0.75 W/cm2. Cells in the baicalein group were treated with baicalein for 24 h at a concentration of 150 μmol/L. In the combination group, cells were treated with both low frequency ultrasound and baicalein. Cells receiving no treatment were designated as the control group. Invasive capacity of cells in the four groups was examined by transwell assay. matrix metalloproteinase 2 (MMP-2), MMP-9, and urokinase type plasminogen activator (u-PA) mRNA and protein levels were examined using Real-time PCR and Western blotting, respectively.
Results: The invasive capacity of cells in the low frequency group, baicalein group and the combination group was significantly reduced by 21.6%±1.68%, 31.9%±2.19% and 51.6%±2.01%, respectively. The expression levels of both mRNA and protein of MMP-2, MMP-9, and u-PA were significantly decreased in all three treatment groups, compared to that in the control group. The decline in the expression of MMP-2, MMP-9 and u-PA was highest in the combination group at both mRNA and protein levels.
Conclusions: Low frequency ultrasound combined with baicalein can effectively reduce the invasive capacity of breast cancer, probably by downregulating the expression of MMP-2, MMP-9, and u-PA.
