Globally colorectal cancer ranks as the third most widespread disease and the third leading cause of cancer-associated mortality. Immunotherapy treatments like PD-L1 blockade have been used to inhibit the PD-L1 legend, which boosts the activity of cytotoxic T lymphocytes. Recently, studies suggest that some probiotics could potentially enhance the effectiveness of immunotherapy treatments for cancer patients. We found that in Caco-2 and HT-29 cells, the live Leuconostoc mesenteroides treatment resulted an increase in the PD-L1 expression and this treatment stimulated interferon-gamma (IFN-γ) production in Jurkat T-cells. Due to the well-established ability of IFN-γ to enhance PD-L1 expression, the combination of IFN-γ and L. mesenteroides was used in colon cancer cell lines and a resulting remarkable increase of over tenfold in PD-L1 expression was obtained. Interestingly, when L. mesenteroides and IFN-γ are present, the blockage of PD-L1 using PD-L1 antibodies not only improved the viability of Jurkat T-cells but also significantly boosted the levels of IFN-γ and IL-2, the T-cells activation marker cytokines. In addition to upregulating PD-L1, L. mesenteroides also activated Toll-like receptors (TLRs) and NOD-like receptors (NODs) pathways, specifically through TLR2 and NOD2, while also exerting a suppressive effect on autophagy in colon cancer cell lines. In conclusion, our findings demonstrate a significant upregulation of PD-L1 expression in colon cancer cells upon co-culturing with L. mesenteroides. Moreover, the presence of PD-L1 antibodies during co-culturing activates Jurkat T cells. The observed enhancement in PD-L1 expression may be attributed to the inhibition of the Autophagy pathway or activation of the hippo pathway. Graphical abstract text: The administration of Live Lactobacillus mesenteroides on colon cancer cells leads to the elevation of PD-L1, with a further increase observed in the presence of IFN-γ. Co-cultivation of Live L. mesenteroides with colon cancer cells in conjunction with anti-PD-L1 blockade antibody results in the enhanced viability of T cells. Key Points: Co-culturing L. mesenteroides increases PD-L1 gene and protein transaction in colon cancer. L. mesenteroides existing enhances T cells viability and activity. GPCR41/42 is a possible link between L. mesenteroides, YAP-1 and PD-L1.

The aim of this study was to evaluate the anticancer effects of piceatannol, a natural stilbenoid, on human neuroblastoma cells. In order to accomplish this goal, we performed various cellular assays, including the XTT cell proliferation assay for cell viability, colony formation assay for colony formation capacity, FITC Annexin V and cell death detection kit for apoptosis, matrigel invasion assay for invasion capacity, intracellular reactive oxygen species (ROS) red dye for intracellular ROS levels, TMRM staining method for mitochondrial membrane potential (MMP), and the CYTO‐ID autophagy detection kit for autophagy. Furthermore, we analyzed the expression levels of genes associated with apoptosis and autophagy using RT‐qPCR. Based on our findings, piceatannol exhibited cytotoxic effects on neuroblastoma cells. Besides, treatment with piceatannol at both 50 and 100 μM concentrations for 72 h decreased colony formation, induced apoptosis and autophagy, inhibited cell invasion, decreased MMP, and increased ROS levels in SH‐SY5Y cells. In addition, we observed significant upregulation in the expression levels of CASP8, BECLIN, ATG5, ATG7, and MAPILC3A genes between the two doses. These results suggest that piceatannol enhances autophagic activity and induces caspase‐dependent apoptosis, indicating its potential as a therapeutic agent against neuroblastoma cells.