ABSTRACT
Cancer immunotherapy has become a new generation of anti-tumor treatment, but its indications still focus on several types of tumors that are sensitive to the immune system. Therefore, effective strategies that can expand its indications and enhance its efficiency become the key element for the further development of cancer immunotherapy. Natural products are reported to have this effect on cancer immunotherapy, including cancer vaccines, immune-check points inhibitors, and adoptive immune-cells therapy. And the mechanism of that is mainly attributed to the remodeling of the tumor-immunosuppressive microenvironment, which is the key factor that assists tumor to avoid the recognition and attack from immune system and cancer immunotherapy. Therefore, this review summarizes and concludes the natural products that reportedly improve cancer immunotherapy and investigates the mechanism. And we found that saponins, polysaccharides, and flavonoids are mainly three categories of natural products, which reflected significant effects combined with cancer immunotherapy through reversing the tumor-immunosuppressive microenvironment. Besides, this review also collected the studies about nano-technology used to improve the disadvantages of natural products. All of these studies showed the great potential of natural products in cancer immunotherapy.
ABSTRACT
Objective To explore the role of pigment epithelium-derived factor (PEDF) in vascular endothelial cells dysfunction induced by sodium arsenite (NaAsO2).Methods Human umbilical vein endothelial cells (EA.Hy926 cells) were treated with different levels of NaAsO2 [0 (control),1,2,5,10,20,50 μmol/L] for 24 hours.The cell viability was determined using CCK8.Colorimetric assay was used to detect the activity of inducible nitric oxide synthase (iNOS) in culture supematants,PEDF content in the supematant of EA.Hy926 cells was detected by enzyme-linked immunosorbent assay (ELISA),and nitric oxide (NO) content in cells was detected by flow cytometry.Results Compared with the control group [(101.08 ± 3.22)％],the cell viability of 20 μ mol/L group [(80.69 ± 7.95)％] and 50 μmol/L group [(69.87 ± 10.54)％] decreased significantly,and the differences were statistically significant (P ＜ 0.05).The activity of iNOS increased significantly in 10,20,50 μmol/L groups [(829.1 ± 68.2),(772.3 ± 37.1),(874.6 ± 43.5) U/L],respectively,in comparison with that of the control group [(397.5 ± 43.5) U/L] in the cell culture supematant (P ＜ 0.01).Similarly,PEDF levels in the groups of 10,20,50 μmol/L [(12.06 ± 0.55),(11.97 ± 0.39) and (13.89 ± 0.26) mg/L respectively] were higher than that of the control group [(10.70 ± 0.35) mg/L,P ＜ 0.01],and the highest content of PEDF was found in 50 μmol/L group.The NO level in 50 μmol/L group (11 558.99 ± 397.43) was significantly lower than that of the control group (14 131.49± 262.61,P ＜ 0.01).Conclusion PEDF is involved in the vascular endothelial cells dysfunction induced by arsenic.