Effects of the ethanol extract of <i>Neopyropia yezoensis</i>, cultivated in the Seto Inland Sea (Setonaikai), on the viability of 10 human cancer cells including endocrine therapy-resistant breast cancer cells

Here, we established an ethanol extraction method and obtained extracts of Neopyropia yezoensis cultivated in three different locations (extracts A-C) in the Seto Inland Sea (Setonaikai). The effects of the extracts on 10 human cancer cells derived from seven different organs were investigated. Extract A exerted the strongest anti-proliferative effects on all types of cancer cells, including an endocrine therapy-resistant aggressive breast cancer model, LTED cells. We analyzed the effects of the extracts on MCF-7 (parental cells for producing LTED cells)/LTED cells, along with four established anti-proliferative agents (etoposide, LY2835219, paclitaxel, and trichostatin A) with different action mechanisms. The inhibitory effects of extract A on both breast cancer cells were comparable with those of paclitaxel, although the other agents showed a preferable reduction in MCF-7 cell viability. We provide evidence of the involvement of component(s), especially those of extract A of N. yezoensis, which exerted anti-proliferative effects on cancer cells.