Strobilanthes crispus inhibits migration, invasion and metastasis in breast cancer

Strobilanthes crispus (L.) Blume, locally known in Malaysia as "Pecah kaca" or "Jin batu", has been traditionally used for treatment of various ailments including cancer. We previously demonstrated that a standardized bioactive subfraction of S. crispus, termed as F3, possessed potent anticancer effects in both in vitro and in vivo breast cancer models.

To investigate the potential of F3 from S. crispus to prevent metastasis in breast cancer.

The antimetastatic effects of F3 were first investigated on murine 4T1 and human MDA-MB-231 breast cancer cell (BCC) lines using cell proliferation, wound healing and invasion assays. A 4T1-induced mouse mammary carcinoma model was then used to determine the expression of metastasis tumor markers, epithelial (E)-cadherin, matrix metalloproteinase (MMP)-9, mucin (MUC)-1, nonepithelial (N)-cadherin, Twist, vascular endothelial growth factor (VEGF) and vimentin, using immunohistochemistry, following oral treatment with F3 for 30 days.

Significant growth arrest was observed with F3 IC₅₀ values of 84.27 µg/ml (24 h) and 74.41 µg/ml (48 h) for MDA-MB-231, and 87.35 µg/ml (24 h) and 78.75 µg/ml (48 h) for 4T1 cells. F3 significantly inhibited migration of both BCC lines at 50 μg/ml for 24 h (p = 0.018 and p = 0.015, respectively). Similarly, significant inhibition of invasion was demonstrated in 4T1 (75 µg/ml, p = 0.016) and MDA-MB-231 (50 µg/ml, p = 0.040) cells compared to the untreated cultures. F3 treatment resulted in reduced tumor growth compared to untreated mice (p < 0.01) or mice treated with tamoxifen (p < 0.05). Statistical parameters (absolute count, proportion, intensity and overall scores) indicating upregulation of E-cadherin expression were statistically significant in F3-treated compared to the untreated tumor-bearing mice. Similarly, F3 significantly reduced the expression of MMP-9, MUC1, N-cadherin, Twist, VEGF and vimentin in comparison with the TM (p < 0.01) group CONCLUSIONS: Our findings suggest that F3 exerts anti-metastatic effects independent of its cytotoxic effects, and these are supported by the increased expression of E-cadherin concurrent with downregulation of MMP-9, MUC1, N-cadherin, Twist, VEGF and vimentin expression in breast cancer.