Anticancer Activity of Holothuria atra Extracts on the Triple-Negative Breast Cancer Cell Line MDA-MB-231

Holothuria atra (HA), black sea cucumber, has been widely used as a traditional medicine in several Asian countries. A previous study showed the potent anticancer effects of HA extracts on cell proliferation and apoptosis in various types of cancer cell lines, including breast cancer cells. However, the molecular mechanism by which HA extracts exert anticancer effects on the triple-negative breast cancer cell line MDA-MB-231 remains unclear and poorly understood. In the present study, we assessed the inhibitory effects of body wall (BW) and visceral (VS) extracts of HA on proliferation, adhesion, migration, invasion, and tube formation in an in vitro model of the highly metastatic triple-negative breast cancer cell line MDA-MB-231. BW and VS extracts were prepared by the ethyl acetate extraction process. Anticancer properties, including the inhibition of proliferation, adhesion, migration, invasion, and tube formation, were examined by MTT assays, cell adhesion assays, wound healing migration assays, Matrigel invasion assays, and tube formation assays, respectively. The protein expression levels of Bax, Bcl-2, Caspase-3, Akt, matrix metalloproteinase-2 (MMP-2), and matrix metalloproteinase-9 (MMP-9) were examined by Western blot analysis. Our findings demonstrated that BW extract treatment exhibited significantly greater inhibitory effects on MDA-MB-231 cell proliferation in a time- and dose-dependent manner than VS extract treatment. Moreover, dose-dependent suppression of MDA-MB-231 cell adhesion, migration, invasion, and tube formation was observed in the BW extract-treated group. The inhibition of MDA-MB-231 cells invasion in the BW extract-treated group was achieved by suppressing the levels of MMP-2 and MMP-9 through the Akt/MMP pathway. MDA-MB-231 cell apoptosis was promoted after treatment with BW extract by downregulating Bcl-2 levels and upregulating Bax and Caspase-3 expression through Akt/Bad signaling. Our study revealed the anticancer effects of BW extracts of HA. This study provides a potential therapeutic strategy using beneficial HA components for treating patients with breast cancer. Funding Information: This research was funded by Mahidol University and the Thailand Research Fund (Grant IRG5780011). Declaration of Interests: The authors declare no conflict of interest.