Antitumor effects of baicalin on ovarian cancer cells through induction of cell apoptosis and inhibition of cell migration in vitro

Abstract

Baicalin, an active flavone isolated from Scutellaria baicalensis Georgi, has been demonstrated to induce various beneficial biochemical effects such as anti‑inflammatory, anti‑viral, and antitumor effects. However, the antitumor mechanism of baicalin is not well understood. In the present study, baicalin was demonstrated to inhibit the viability and migration of a widely used ovarian cancer cell line, A2780, in a dose‑dependent manner. MTT assays revealed that cell viability significantly decreased in ovarian cancer cells treated with baicalin compared with untreated cells, without effect on normal ovarian cells. Flow cytometric analysis indicated that baicalin suppressed cell proliferation by inducing apoptosis. The underlying mechanisms involved were indicated to be downregulation of the anti‑apoptotic protein B‑cell lymphoma 2 apoptosis regulator and activation of caspase‑3 and ‑9. In addition, wound healing and transwell assays revealed that cell migratory potential and expression of matrix metallopeptidase (MMP)‑2 and MMP‑9 were significantly inhibited when cells were exposed to baicalin, compared with untreated cells. The present study therefore suggested that baicalin has the potential to be used in novel anti‑cancer therapeutic formulations for treatment of ovarian cancer.

Figure 1.

Effects of baicalin on ovarian cancer cell and normal ovarian cell viability. (A) Chemical structure of baicalin. (B) Viability of A2780 ovarian cancer cells and IOSE80 normal ovarian cells was determined by MTT assay following treatment with 0, 40, 80, 120, 160, 200 or 240 µM baicalin for 24 h. Data are presented as the mean ± standard deviation of 3 replicates. **P<0.01 and ***P<0.001 vs. the 0 µM control group.

Figure 2.

Baicalin induces apoptosis in A2780 ovarian cancer cells. (A) Cell nucleus morphology in cells treated with 0, 80 or 160 µM baicalin was observed by DAPI staining (original magnification, ×100). (B) Apoptosis was detected by Annexin V/PI staining following treatment with 0, 80 or 160 µM baicalin. Early apoptotic cells (Annexin V⁺/PI⁻) are shown in the lower right quadrant of the chart, while the upper right quadrant indicates late apoptotic cells (Annexin V⁺/PI⁺). Quantitative data are presented as the mean ± standard deviation of 3 replicates. **P<0.01 and ***P<0.001 vs. the 0 µM control group. PI, propidium iodide.

Figure 3.

Effects of baicalin on A2780 ovarian cancer cell migration, assessed by wound healing assay. Cells were scraped with a pipette tip and treated with 0, 20 or 40 µM baicalin for 24 h. Cells were imaged under a light microscope (original magnification, ×100) before and after injury. Cell migration was quantified by measuring wound closure areas before and after injury. Quantitative data are presented as the mean ± standard deviation of 3 replicates. **P<0.01 and ***P<0.001 vs. the 0 µM control group.

Figure 4.

Effects of baicalin on A2780 ovarian cancer cell migration, assessed by transwell assay. Cells were treated. Images represent cell migration to the underside of transwell membranes following treatment with 0, 20 or 40 µM baicalin for 24 h (original magnification, ×200). Quantitative data are presented as the mean ± standard deviation of 3 replicates, relative to the 0 µM control group. **P<0.01 and ***P<0.001 vs. the 0 µM control group.

Figure 5.

Effects of baicalin on protein expression levels of MMP-2 and −9. Protein expression levels of MMP-9 and MMP-2 were assessed by western blotting analysis following treatment with 0, 20 or 40 µM baicalin for 24 h. β-actin served as a loading control. Quantitative data are presented as the mean ± standard deviation of 3 replicates. **P<0.01 vs. the 0 µM control group. MMP, matrix metallopeptidase.

Figure 6.

Effects of baicalin on protein expression levels of apoptosis-related proteins. Protein expression levels of cleaved caspase-3, cleaved caspase-9 and Bcl-2, were assessed by western blotting analysis following treatment with 0, 80 or 160 µM baicalin for 24 h. β-actin served as a loading control. Quantitative data are presented as the mean ± standard deviation of 3 replicates. **P<0.01 and ***P<0.001 vs. the 0 µM control group. Bcl-2, B-cell lymphoma 2 apoptosis regulator.