Renal cell carcinoma (RCC) microenvironment plays critical roles in antitumor immune response. Resveratrol exhibits a direct antitumor effect in various tumor models. However, the immunomodulatory effect of resveratrol on RCC microenvironment is unknown. In this study, we found that administration of low dose of resveratrol inhibits Renca tumor growth and its inhibition effect depends on CD8(+) T cells. Moreover, the proportion of regulatory T cells is decreased, while the proportion of myeloid-derived suppressor cells does not alter after resveratrol treatment. More importantly, massive amount of activated CD8(+) T cells accumulates in tumor microenvironment in the resveratrol-treated group and shows increased cytotoxicity, as indicated by a higher expression of Fas ligand. We also found that resveratrol switches the expression of T-helper (Th) 2 cytokines such as interleukin (IL)-6 and IL-10 to Th 1 cytokines with dominance of interferon (IFN)-γ, which increases the expression of Fas in Renca cells. Furthermore, we found resveratrol down-regulates angiogenesis along with decreased level of vascular endothelial growth factor in tumor microenvironment. Our results strongly suggest that resveratrol might be used for RCC immunotherapy through modulating tumor microenvironment.

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Background. Inducible nitric oxide synthase (iNOS) is confirmed to regulate the production of nitric oxide (NO) when cells are exposed to external stimulus. Recent publications revealed that overexpression of iNOS predicted poor clinical outcomes for patients with malignant cancers, e.g., gastric, bladder, and colorectal cancers; however, several studies reported no obvious relationship between iNOS expression and prognosis of solid tumors. The aim of our study was to investigate the pooled effect of the prognostic value of iNOS expression. Materials and Methods. We performed a systematic search of PubMed, Web of Science, and Embase databases up to January 15, 2019. The concerned outcomes of interest included overall survival (OS), cancer-special survival (CSS), and recurrence-free survival (RFS). Results. Fourteen studies with 1,758 patients were included in this meta-analysis, and we reached the conclusion that increased iNOS expression was significantly associated with worse OS (HR: 1.89, 95% CI: 1.57 - 2.28, p ≤ 0.001), worse CSS (HR: 3.13, 95% CI: 1.88 - 5.20, p ≤ 0.001), and worse RFS (HR: 2.16, 95% CI: 1.29 - 3.62, p = 0.003) in solid tumors. Furthermore, the subgroup analysis identified the significant relationship of high iNOS expression with poor OS in gastric cancer. No obvious publication bias was detected by Begg’s tests. Conclusion. In summary, the results drawn in our meta-analysis demonstrated that elevated expression of iNOS had a significant association with poor survival in human cancer. iNOS might serve as a promising predictive biomarker of prognosis in cancer patients, and well-designed prospective studies are further needed to substantiate the prognostic value of iNOS.

Ferroptosis is an iron-dependent lipid peroxidation process. Although the involvement of ferroptosis in kidney diseases has recently been reported, the association between ferroptosis and urolithiasis remains unclear. The present study examined the effects of ferroptosis on calcium oxalate (CaOx) crystal-induced renal tubular epithelial cell injury in vivo and in vitro . First, renal tubular epithelial cells were exposed to various concentrations of CaOx. By measuring cell viability, Fe 2+ levels, lipid peroxidation levels and the levels of ferroptosis-related proteins, it was identified that the relative expression of the ferroptosis agonist proteins, p53, long-chain acyl-CoA synthetases (ACSL4), transferrin (TF) and trans-ferrin receptor (TRC), increased, while the relative expression of the ferroptosis inhibitory proteins, solute carrier family 7 member 11 (SLC7A11, XCT) and glutathione peroxidase 4 (GPX4), decreased significantly. Furthermore, the levels of Fe 2+ and lipid peroxidation gradually increased, while cell viability significantly decreased. From these results, it was noted that the extent of CaOx-induced ferroptosis activation and cell injury was dependent on the CaOx concentration. To further investigate the association between ferroptosis and renal tubular epithelial cell injury, the ferroptosis agonist, erastin, and the ferroptosis inhibitor, ferrostatin-1, were used to regulate the degree of ferroptosis at the same CaOx concen-tration in in vivo and in vitro experiments. CaOx-induced ferroptosis and damage to renal tubular epithelial cells and renal tissue were investigated. Finally, it was identified that through the regulation of ferroptosis levels, renal tubular epithelial cell injury increased significantly when the ferrop-tosis level increased, and vice versa. On the whole, the present results indicated that ferroptosis is essential for renal tubular epithelial cell injury induced by CaOx crystals. This finding is highly significant and promotes the further investigation of the association between ferroptosis and urolithiasis.