Screening of five Sri Lankan endemic plants for anti-cancer effects on breast cancer stem cells isolated from MCF-7 and MDA-MB-231 cell lines

Purpose: To screen selected endemic plants grown in Sri Lanka on breast cancer stem cells (bCSCs) for their anti-cancer properties Methods: Breast-CSCs expressing CD24 - /CD44 + surface markers were isolated from MDA-MB-231 cells by magnetic-assisted cell sorting method and validated using flow cytometry. A panel of forty extracts from barks and leaves of Doona nervosa , Garcinia quaesita , Garcinia zeylanica , Memecylon rostratum and Schumacheria castaneifolia were obtained by sequential solvent extraction and tested on bCSC-mammospheres derived from MDA-MB-231 and MCF-7 cells and normal mammary epithelial (MCF-10A) cells. Proliferation and cell stemness were analyzed using WST-1 cell proliferation assay and alkaline phosphatase assay. Results: Hexane and chloroform extracts of G. zeylanica and G. quaesita barks showed dosedependent reduction in proliferation and stemness in both bCSCs tested with less effect on MCF-10A cells. Hexane, chloroform and ethyl acetate extracts of S. castaneifolia bark selectively inhibited mammospheres of triple negative bCSCs cells. Conclusion: This study demonstrates that the non-polar extracts of G. zeylanica and G. quaesita , S. castaneifolia barks inhibit the proliferation of bCSCs of triple negative and estrogen-progesterone positive breast cancers. Findings of the present study may useful for developing a future anti-cancer therapeutics which can target bCSCs. Keywords: Cancer stem cells, Garcinia zeylanica , Garcinia quaesita , Schumacheria castaneifolia , Mammospheres