Dual anticancer and immunoregulatory actions of blueberry stem extract in breast cancer cells and peripheral blood mononuclear cells

Blueberry stem extract (BSE), which contains phenolic compounds like proanthocyanidins, reduces liver lipid synthesis, boosts anti-adult T-cell leukemia action, protects retinal cells from blue light damage, and prevents lacrimal hyposecretion. However, the anticancer functions and immunomodulatory effects of BSE are not well understood. To assess the anticancer properties of BSE, MCF-7 and MDA-MB-231 breast cancer (BC) cells were treated with various concentrations of BSE. BSE suppressed the growth of BC cells in a manner dependent on both dose and exposure times. Furthermore, it triggered apoptosis by disrupting mitochondrial membrane potential. BSE also inhibited cell motility in BC cells. Notably, it reduced the expression of PD-1, TIGIT, and LAG-3 immune checkpoint proteins in peripheral blood mononuclear cells, which are critical for antitumor immune response. These findings suggest that BSE has promising anticancer and immunomodulatory properties that warrant further investigation in preclinical models.