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Abstract Background Targeting the tumor microenvironment represents an emerging therapeutic strategy for cancer. Macrophages are an essential part of the tumor microenvironment. Macrophage polarization is modulated by mitochondrial metabolism, including oxidative phosphorylation (OXPHOS), the tricarboxylic acid (TCA) cycle, and reactive oxygen species content. Isocitrate dehydrogenase 2 (IDH2), an enzyme involved in the TCA cycle, reportedly promotes cancer progression. However, the mechanisms through which IDH2 influences macrophage polarization and modulates tumor growth remain unknown. Methods In this study, IDH2-deficient knockout (KO) mice and primary cultured bone marrow-derived macrophages (BMDMs) were used. Both in vivo subcutaneous tumor experiments and in vitro co-culture experiments were performed, and samples were collected for analysis. Western blotting, RNA quantitative analysis, immunohistochemistry, and flow cytometry were employed to confirm changes in mitochondrial function and the resulting polarization of macrophages exposed to the tumor microenvironment. To analyze the effect on tumor cells, subcutaneous tumor size was measured, and growth and metastasis markers were identified. Results IDH2-deficient macrophages co-cultured with cancer cells were found to possess increased mitochondrial dysfunction and fission than wild-type BMDM. Additionally, the levels of M2-associated markers decreased, whereas M1-associated factor levels increased in IDH2-deficient macrophages. IDH2-deficient macrophages were predominantly M1. Tumor sizes in the IDH2-deficient mouse group were significantly smaller than in the wild-type mouse group. IDH2 deficiency in macrophages was associated with inhibited tumor growth and epithelial–mesenchymal transition. Conclusions Our findings suggest that IDH2 deficiency inhibits M2 macrophage polarization and suppresses tumorigenesis. This study underlines the potential contribution of IDH2 expression in macrophages and tumor microenvironment remodeling, which could be useful in clinical cancer research.

Background: The overall objective of this study is to confirm that normal expression of yeast NADH-dehydrogenase (NDI1) can occur in neural stem cell lines of minipig with resistance to rotenone exposure, an environmental factor responsible for dysfunction of mitochondrial enzyme complex I. In modern society, there are many diseases that cannot be treated. Diseases including LHON, Parkinson disease and dystonia, have been associated with defects in mitochondrial complexes. This experiment was performed to demonstrate that it was not sensitive. The overall objective of this study is to confirm that normal expression of yeast NADHdehydrogenase (NDI1) can occur in neural stem cell lines of minipig with resistance to rotenone exposure, an environmental factor responsible for dysfunction of mitochondrial enzyme complex I. Methods: A Mini Pig Neural stem cell line (MPV) was used for transfection of the NDI gene, DMEM/F-12 culture medium and MPV was inoculated in a six-well plate (Corning, USA) at a concentration of 1x105 cells/3 ml/well, with inoculation of MPV at 37°C for 24 hours, 5% CO2, followed by incubation in an incubator with 95% humidity and attached. The plate containing MPV cells was treated with recombinant adeno-associated virus ndi1 (rAAV-ndi1) for transfection, with periodic replacement with a cell selection culture solution containing 10% FBS, 1% P/S and 0.2 μM rotenone. The experiment was performed for restoration of mitochondrial activity of thawed cells. RNA was extracted from MPV cells and transfection of MPV cells with the NDI1 gene was performed using Trizol (Invitrogen, USA). Reverse transcription PCR (RT-PCR) and Western blot were performed to confirm normal expression of the NDI1 gene in MPV cells transfected with the NDI1 gene. Immunofluorescence was performed to determine the presence of the NDI1 protein in the cell and the cell count was used for LUNA and the rate of cell death for rotenone was determined using the MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt] assay. Result: rAAV-NDI1 was successfully introduced into MPV cells and the proliferation rates for the cells were compared with those of the transformed cells; after three days, the non-infected cells were killed and the infected cells proliferated. The results after differentiating the cell lines were similar to those of previously reported studies. Toxicity analysis on rotenone was also performed using the MTS assay and the rates of cell death over three days were compared; the results showed significantly lower levels of NDI1-transformed minipig neural stem cells compared with those of minipig. The present work will be a complementary contribution to the comprehensive study of the scorpion sting syndrome. These results were similar to those of previously reported studies. Previous studies have reported that oxidoreductive stress can be a cause of apoptosis. Therefore, conduct of additional studies for measurement of ROS and oxygen utilization to determine oxidative stress in cells will be necessary. [ABSTRACT FROM AUTHOR]

Purpose: Nivolumab and regorafenib are second-line therapies for patients with advanced hepatocellular carcinoma (HCC). We aimed to compare the effectiveness of nivolumab and regorafenib. Materials and Methods: We retrospectively reviewed patients with HCC treated with nivolumab or regorafenib after sorafenib failure. Progression-free survival (PFS) and overall survival (OS) were analyzed. An inverse probability of treatment weighting using the propensity score (PS) was performed to reduce treatment selection bias. Results: Among the 189 patients recruited, 137 and 52 patients received regorafenib and nivolumab after sorafenib failure, respectively. Nivolumab users showed higher Child-Pugh B patients (42.3% vs. 24.1%) and shorter median sorafenib maintenance (2.2 months vs. 3.5 months) compared to regorafenib users. Nivolumab users showed shorter median OS (4.2 months vs. 7.4 months, p=0.045) than regorafenib users and similar median PFS (1.8 months vs. 2.7 months, p=0.070). However, the median overall and PFS did not differ between the two treatment groups after the 1:1 PS matching (log-rank p=0.810 and 0.810, respectively) and after the stabilized inverse probability of treatment weighting (log-rank p=0.445 and 0.878, respectively). In addition, covariate-adjusted Cox regression analyses showed that overall and PFS did not significantly differ between nivolumab and regorafenib users after 1:1 PS matching and stabilized inverse probability of treatment weighting (all p>0.05). Conclusion: Clinical outcomes of patients treated with nivolumab and regorafenib after sorafenib treatment failure did not differ significantly. [ABSTRACT FROM AUTHOR]