The bound polyphenols of foxtail millet (Setaria italica) inner shell inhibit breast cancer by promoting lipid accumulation-induced autophagic death

Foxtail millet is a traditional excellent crop with high nutritional value in the world, belong to cereals. The bran of foxtail millet is rich in polyphenol that has antioxidant, anti-inflammatory, and anti-tumorigenic effects. Previously, we extracted bound polyphenols from the inner shell of foxtail millet bran (BPIS). Here, we report that BPIS specifically induced breast cancer cell death and elevated the autophagy level simultaneously. The addition of an autophagy inhibitor blocked BPIS-induced breast cancer cell death, indicating that excessive autophagy induced cell death. Furthermore, oil red O and BODIPY staining also confirmed that lipids, which are important inducers of autophagy, accumulated in breast cancer cells treated with BPIS. Lipidomics research revealed that glycerophospholipids were the main accumulated lipids induced by BPIS. Further study showed that elevated PCYT1A expression was responsible for glycerophospholipid accumulation, and BPIS contained ferulic acid and p-coumaric acid, which induced PCYT1A expression and breast cancer cell death. Collectively, our results revealed that BPIS resulted in autophagic death by enhancing lipid accumulation in breast cancer cells, and BPIS contains ferulic acid and p-coumaric acid, which provided new insights into developing nutraceuticals and drugs for breast cancer patients. [Display omitted] •BPIS specifically induced the death of breast cancer cells, but not the normal.•BPIS-triggered excessive autophagy was the inducement of breast cancer cell death.•BPIS-induced lipid accumulation promoted autophagic death in breast cancer cells.•PCYT1A was the key of BPIS-induced lipid accumulation of breast cancer cells.•BPIS has the potential as a nutraceutical for breast cancer patients.