Plant-derived polyphenols are bioactive compounds with potential health-promoting properties including antioxidant, anti-inflammatory, and anticancer activity. However, their beneficial effects and biomedical applications may be limited due to their low bioavailability. In the present study, we have considered a microencapsulation-based drug delivery system to investigate the anticancer effects of polyphenol-rich (apigenin, caffeic acid, and luteolin) fractions, extracted from a cereal crop pearl millet (Pennisetum glaucum), using three phenotypically different cellular models of breast cancer in vitro, namely triple negative HCC1806, ER-positive HCC1428, and HER2-positive AU565 cells. Encapsulated polyphenolic extract induced apoptotic cell death in breast cancer cells with different receptor status, whereas it was ineffective against non-tumorigenic MCF10F cells. Encapsulated polyphenolic extract was also found to be cytotoxic against drug-resistant doxorubicin-induced senescent breast cancer cells that were accompanied by increased levels of apoptotic and necrotic markers, cell cycle inhibitor p21 and proinflammatory cytokine IL8. Furthermore, diverse responses to the stimulation with encapsulated polyphenolic extract in senescent breast cancer cells were observed, as in the encapsulated polyphenolic extract-treated non-proliferating AU565 cells, the autophagic pathway, here cytotoxic autophagy, was also induced, as judged by elevated levels of beclin-1 and LC3b. We show for the first time the anti-breast cancer activity of encapsulated polyphenolic extract of pearl millet and postulate that microencapsulation may be a useful approach for potentiating the anticancer effects of phytochemicals with limited bioavailability.
植物源多酚是具有潜在健康促进特性的生物活性化合物，包括抗氧化、抗炎和抗癌活性。然而，由于其生物利用度较低，其有益效应和生物医学应用可能受到限制。本研究采用基于微胶囊化的药物递送系统，通过三种表型不同的乳腺癌细胞模型（即三阴性HCC1806细胞、雌激素受体阳性HCC1428细胞和人表皮生长因子受体2阳性AU565细胞），在体外研究了从谷类作物珍珠粟中提取的富含多酚（芹菜素、咖啡酸和木犀草素）组分的抗癌作用。微胶囊化多酚提取物能诱导不同受体状态的乳腺癌细胞发生凋亡性细胞死亡，而对非致瘤性MCF10F细胞无效。研究还发现，微胶囊化多酚提取物对耐药性阿霉素诱导的衰老乳腺癌细胞具有细胞毒性作用，同时伴随凋亡和坏死标志物、细胞周期抑制剂p21及促炎细胞因子IL8水平升高。此外，在衰老乳腺癌细胞中观察到对微胶囊化多酚提取物刺激的多样化反应：在经微胶囊化多酚提取物处理的非增殖性AU565细胞中，通过beclin-1和LC3b水平升高可判断其自噬通路（此处为细胞毒性自噬）也被激活。本研究首次揭示了珍珠粟微胶囊化多酚提取物的抗乳腺癌活性，并提出微胶囊化可能是增强生物利用度有限的植物化学物质抗癌效应的有效策略。
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