Abstract:
PURPOSE : Breast cancer metastasis relies on cellular invasion and angiogenesis facilitated by the downregulation of metastatic
suppressor proteins like Cluster of Differentiation 82 (CD82). Currently, no medicines target multiple systems to prevent
metastatic progression through CD82 upregulation. This study screened for plant extracts displaying effects on cell proliferation,
invasion, and CD82 expression in breast cancer cells, and in vivo angiogenesis, and further correlated between the
biological activities and effect on CD82 expression.
METHODS : Seventeen ethanolic plant extracts were screened for their effect on cell proliferation (against MDA-MB-231 and
MCF-7 breast cancer and Hek293 kidney cells), cell invasion and effect on CD82 expression in metastatic MDA-MB-231
cells. Selected extracts were further evaluated for in vivo anti-angiogenesis.
RESULTS : Extracts displayed varying antiproliferative activity against the different cell lines, and those that showed selectivity
indexes (SI) > 0.5 against MDA-MB-231 were selected for anti-invasion evaluation. Buddleja saligna Willd. (BS), Combretum
apiculatum Sond. (CA), Foeniculum vulgare, Greyia radlkoferi, Gunnera perpensa and Persicaria senegalensis (Meisn.)
Soják (PS) displayed 50% inhibitory concentration (
IC50) values of 44.46 ± 3.46, 74.00 ± 4.48, 180.43 ± 4.51, 96.97 ± 2.29,
55.29 ± 9.88 and 243.60 ± 2.69 μg/mL, respectively against MDA-MB-231, and compared to Hek293 showed SI of 0.9,
0.7, 1.4, 1.1, 2.2 and 0.5. Significant invasion inhibition was observed at both 20 and 40 μg/mL for BS (94.10 ± 0.74 and
96.73 ± 0.95%) and CA (87.42 ± 6.54 and 98.24 ± 0.63%), whereas GR (14.91 ± 1.62 and 41 ± 1.78%) and PS (36.58 ± 0.54
and 51.51 ± 0.83%), only showed significant inhibition at 40 μg/mL, and FV (< 5% inhibition) and GP (10 ± 1.03 and
22 ± 1.31%) did not show significant inhibition at both concentrations. Due to the significant anti-invasive activity of BS,
CA and PS at 40 μg/mL, these extracts were further evaluated for their potential to stimulate CD82. BS showed significant
(p < 0.05) reduction in CD82 at 20 and 40 μg/mL (13.2 ± 2.2% and 20.3 ± 1.5% decrease, respectively), whereas both CA and
PS at 20 μg/mL increased (p < 0.05) CD82 expression (16.4 ± 0.8% and 5.4 ± 0.6% increase, respectively), and at 40 μg/mL
significantly reduced CD82 expression (23.4 ± 3.1% and 11.2 ± 2.9% decrease, respectively). Using the yolk sac membrane
assay, BS (59.52 ± 4.12 and 56.72 ± 3.13% newly formed vessels) and CA (83.33 ± 3.17 and 74.00 ± 2.12%) at both 20 and 40 μg/egg showed significant (p < 0.001) angiogenesis inhibition, with BS showing statistical similar activity to the positive
control, combretastatin A4 (10 nmol/egg), whereas PS only displayed significant (p < 0.001) angiogenesis stimulation at
40 μg/egg (120.81 ± 3.34% newly formed vessels).
CONCLUSION : BS exhibits antiproliferative, anti-invasive, and anti-angiogenic activity despite inhibiting CD82, suggesting an
alternative mode of action. CA at 20 μg/mL shows moderate anti-invasive and anti-angiogenic potential by stimulating CD82,
while at 40 μg/mL it still displays these properties but inhibits CD82, suggesting an additional mode of action. PS, with
the least antiproliferative activity, stimulates CD82 and inhibits angiogenesis at 20 μg/mL but inhibits CD82 and increases
angiogenesis at 40 μg/mL, indicating CD82 targeting as a major mode of action. Future studies should explore breast cancer xenograft models to assess the extracts’ impact on CD82 expression and angiogenesis in the tumor microenvironment, along
with isolating bioactive compounds from the extracts.
