Lactate inhibits interferon-α response in ovarian cancer by inducing STAT1 ubiquitin degradation.

The emergence of lactate, produced by lactate dehydrogenase A (LDHA), as an important regulator of the immune response in tumor development has garnered attention in recent research. But, many questions still need to be clarified regarding the relationship between lactate and anti-tumor immunity. Here, we reported that both exogenous and endogenous lactate reduced the protein level and activation of the signal transducer and activator of transcription 1(STAT1) in ovarian cancer cells. As a consequence, the expression of IFNα-STAT1 regulated genes was weakened. This, in turn, weakened the antitumor effect of IFNα by impeding NKT and CD8+T cells recruitment. Strikingly, we found that LDHA knockdown did not result in the downregulation of STAT1 mRNA level in ovarian cancer cells. Instead, we observed that lactate triggered the degradation of STAT1 through the proteasomal pathway. Notably, we identified that lactate reduced the stability of STAT1 by promoting the expression of F-box only protein 40 (Fbxo40). This protein interacts with STAT1 and potentially acts as an E3 ubiquitin ligase, leading to the induction of STAT1 polyubiquitination and degradation. Importantly, ectopic over-expression of the Fbxo40 gene significantly inhibited the expression of ISGs in LDHA knockdown cells. In the TCGA tumor data, we observed that high expression of Fbxo40 negatively correlates with overall survival in ovarian cancer patients. Collectively, our findings reveal lactate as a negative regulator of the IFNα-STAT1 signaling axis in ovarian cancer. This discovery suggests that strategies aimed at targeting lactate for ovarian cancer prevention and treatment should consider the impact on the IFNα-STAT1 response.

SHARPIN promotes cell proliferation of cholangiocarcinoma and inhibits ferroptosis via p53/SLC7A11/GPX4 signaling.

SHARPIN is a tumor-associated gene involved in the growth and proliferation of many tumor types. A function of SHARPIN in cholangiocarcinoma (CCA) is so far unclear. Here, we studied the role and function of SHARPIN in CCA and revealed its relevant molecular mechanism. The expression of SHARPIN was analyzed in cholangiocarcinoma tissues from patients using immunohistochemistry, quantitative PCR, and western blot analysis. Expression of SHARPIN was suppressed/overexpressed by siRNA silencing or lentiviral overexpression vector, and the effect on cell proliferation was determined by the CCK-8 assay and flow cytometry. Accumulation of reactive oxygen species was measured with MitoTracker, and JC-1 staining showed mitochondrial fission/fusion and mitochondrial membrane potential changes as a result of the silencing or overexpression. The ferroptosis marker solute carrier family 7 member 11 (SLC7A11), glutathione peroxidase 4 (GPX4), and the antioxidant enzymes superoxide dismutase 1 (SOD-1) and SOD-2 were analyzed by western blot. The results showed that SHARPIN expression was increased in CCA tissue, and this was involved in cell proliferation. SHARPIN silencing resulted in accumulated reactive oxygen species, reduced mitochondrial fission, and a reduced mitochondrial membrane potential. Silencing of SHARPIN inhibited the ubiquitination and degradation of p53, and downregulated levels of SLC7A11, GPX4, SOD-1, and SOD-2, all of which contributed to excessive oxidative stress that leads to ferroptosis. Overexpression of SHARPIN would reverse the above process. The collected data suggest that in CCA, SHARPIN-mediated cell ferroptosis via the p53/SLC7A11/GPX4 signaling pathway is inhibited. Targeting SHARPIN might be a promising approach for the treatment of CCA.

Silybin suppresses ovarian cancer cell proliferation by inhibiting isocitrate dehydrogenase 1 activity.

Metabolic reprogramming is a sign of malignant tumors, and targeting the metabolism of tumor cells has become a promising therapeutic approach. Here, we report that Silybin (a nontoxic flavonoid commonly used for liver protection) exhibits prominent anti-tumor effects on human ovarian cancer cells. Treatment of an ovarian cancer cell line with Silybin interfered with glutamine metabolism and the tricarboxylic acid cycle. We applied the drug affinity responsive target stability approach to show that Silybin binds to isocitrate dehydrogenase 1 (IDH1). This combination leads to reduced phosphorylation of IDH1 and inhibits enzyme activity. IDH1 dysfunction significantly increases the ratio of NADP/NADPH in the cell, causing an increase in reactive oxygen species generation. Immunohistochemistry demonstrated that IDH1 was increased in ovarian cancer samples compared with normal para-tumoral tissues. Xenograft murine experiments indicated that Silybin administered orally suppressed the growth of the tumor formed by ovarian cancer cells. In combination, our data strongly suggest that Silybin targets IDH1 in ovarian cancer cells and may be a novel treatment candidate.

The role of S-nitrosylation of PFKM in regulation of glycolysis in ovarian cancer cells.

One of the malignant transformation hallmarks is metabolism reprogramming, which plays a critical role in the biosynthetic needs of unchecked proliferation, abrogating cell death programs, and immunologic escape. However, the mechanism of the metabolic switch is not fully understood. Here, we found that the S-nitrosoproteomic profile of endogenous nitrogen oxide in ovarian cancer cells targeted multiple components in metabolism processes. Phosphofructokinase (PFKM), one of the most important regulatory enzymes of glycolysis, was S-nitrosylated by nitric oxide synthase NOS1 at Cys351. S-nitrosylation at Cys351 stabilized the tetramer of PFKM, leading to resist negative feedback of downstream metabolic intermediates. The PFKM-C351S mutation decreased the proliferation rate of cultured cancer cells, and reduced tumor growth and metastasis in the mouse xenograft model. These findings indicated that S-nitrosylation at Cys351 of PFKM by NOS1 contributes to the metabolic reprogramming of ovarian cancer cells, highlighting a critical role of endogenous nitrogen oxide on metabolism regulations in tumor progression.

The NOTCH-HES-1 axis is involved in promoting Th22 cell differentiation.

BACKGROUND: NOTCH signaling has been shown to play a role in the production of interleukin-22 (IL-22) by CD4+ T cells. Multiple T-helper (Th) cell populations secrete IL-22. Th22 (CD4+IL22+IFNγ-IL17A-) cells are a subgroup of CD4+ effector T cells that primarily generate IL-22. The regulatory mechanisms of the NOTCH signaling pathway involved in differentiation of the Th22 cell subset have not been completely elucidated. This study aimed to further explore the involvement of NOTCH signaling in Th22 differentiation. METHODS: In vitro combination of IL-6, IL-23, and tumor necrosis factor-α (TNF-α) treatment with naïve CD4+ T cells established the Th22 cell induced model. NOTCH signaling was activated by jagged-1 and inhibited by (2S)-N-[(3,5-difluorophenyl) acetyl]-L-alanyl-2-phenyl]glycine 1,1-dimethylethyl ester (DAPT). HES-1 siRNA and HES-1 vector were employed to knock down and induce overexpression of HES-1 to investigate the effect of NOTCH signaling on the differentiation of CD4+T cells into Th22 cells. RESULTS: We observed that the proportion of Th22 cells, along with Hes-1, Ahr, and Il-22 mRNA and protein expression, was increased by both jagged-1 and overexpression of HES-1. On the other hand, after the combined cytokine treatment of cells, and exposure to jagged-1 and DAPT or HES-1 siRNA, there was a decrease in the Th22 cell proportion, mRNA and protein expression of HES-1, AHR, and IL-22. CONCLUSIONS: Our study demonstrates that HES-1 enhancement in AHR and IL-22 up-regulation of NOTCH signaling can promote the skewing of naïve CD4+T cells toward Th22 cells. Also, the results of our study show that HES-1 is a crucial factor in Th22 cell differentiation.

The heterocyclic compound Tempol inhibits the growth of cancer cells by interfering with glutamine metabolism.

Tempol (4-hydroxy-2,2,6,6-Tetramethylpiperidine-1-oxyl, TPL), a nitroxide compound, inhibits proliferation and increases the vulnerability of cancer cells to apoptosis induced by cytotoxic agents. However, the molecular mechanism of TPL inhibiting cancer cell proliferation has not been fully understood. In this study, we evaluated the metabolic effect of TPL on cancer cells and explored its cancer therapeutic potential. Extracellular flow assays showed that TPL inhibited cellular basal and maximal oxygen consumption rates of mitochondrial. 13C metabolic flux analysis showed that TPL treatment had minimal effect on glycolysis. However, we found that TPL inhibits glutamine metabolism by interfering with the oxidative tricarboxylic acid cycle (TCA) process and reductive glutamine process. We found that the inhibitory effect of TPL on metabolism occurs mainly on the step from citrate to α-ketoglutarate or vice versa. We also found that activity of isocitrate dehydrogenase IDH1 and IDH2, the key enzymes in TCA, were inhibited by TPL treatment. In xenograft mouse model, TPL treatment reduced tumor growth by inhibiting cellular proliferation of xenograft tumors. Thus, we provided a mechanism of TPL inhibiting cancer cell proliferation by interfering with glutamine utilization that is important for survival and proliferation of cancer cells. The study may help the development of a therapeutic strategy of TPL combined with other anticancer medicines.

A High-Salt Diet Disturbs the Development and Function of Natural Killer Cells in Mice.

A high-salt diet (HSD) is common worldwide and can lead to cardiovascular disease, chronic inflammation, and autoimmune diseases. Moreover, increasing evidence shows that HSD is closely related to a variety of immune diseases. Natural killer (NK) cells are important innate immune cells that directly kill their targets via degranulation and secretion of interferon gamma (IFN-γ). NK cells play a vital role in resisting viruses and preventing the malignant transformation of cells; however, whether HSD affects the development and function of NK cells has not yet been elucidated. Therefore, the purpose of the present study was to understand the effects of HSD on the development and function of NK cells, in addition to investigating the underlying molecular mechanism. Our results show that the number of NK cells in the spleen and lungs of HSD-fed mice was significantly reduced, which may be due to the inhibition of NK cell proliferation. Further, the development of NK cells in mice was evaluated, and it was found that HSD reduced the effective NK cell subset (CD27+CD11b-). Moreover, it was also found that the ability of NK cells to secrete CD107a and IFN-γ in HSD-fed mice was decreased following stimulation with RMA-S and YAC-1 tumor cells. Finally, the underlying molecular mechanism was evaluated, and it was found that HSD increased the production of reactive oxygen species (ROS) by NK cells, while the expression of CD122 was decreased, suggesting that HSD downregulates CD122 expression in NK cells via ROS signaling, thereby reducing the responsiveness to IL-15 and ultimately inhibiting NK cell function. The present research discovered a novel mechanism by which HSD inhibits the function of NK cells, providing an alternative avenue for the treatment of immune diseases caused by HSD.

Two novel serine proteases from Scylla paramamosain involved in the synthesis of anti-lipopolysaccharide factors and activation of prophenoloxidase system.

Serine proteases (SPs) are important in various immune responses, including prophenoloxidase (proPO) activation, antimicrobial peptides (AMPs) synthesis, and hemolymph coagulation in invertebrates. In this study, SP3 and SP5 of mud crab (Scylla paramamosain) were studied. SP3 and SP5 were expressed in all examined tissues (mainly in hemocytes), and are associated with the immune responses of mud crab to Vibrio parahemolyticus and Staphylococcus aureus, as well as interacted with TRAF6, and are involved in the activation of anti-lipopolysaccharide factors (ALFs) probably through the TLR/NF-κB pathway. Depletion of SP3 inhibited the expression of ALF1, ALF2, ALF3, and ALF6, while knockdown of SP5 significantly decreased ALF5, and ALF6. Furthermore, both SP5 and TRAF6 regulated the PO activity in the hemolymph of mud crab. Overexpression assay showed that both SP3 and SP5 could enhance the promoter activities of ALFs in mud crab. Taken together, the results of this study indicate that SP3 and SP5 might play important roles in the immune system of mud crab against pathogen invasion.

A core/shell/satellite anticancer platform for 808 NIR light-driven multimodal imaging and combined chemo-/photothermal therapy.

In this contribution, a novel multifunctional anti-cancer nanoplatform has been firstly constructed by conjugating a photothermal agent (CuS nanoparticles) and a cancer cell target agent (folic acid, FA) onto the surface of mesoporous silica coated core-shell-shell up-conversion nanoparticles (UCNPs). It was found that the doxorubicin (DOX) loaded system exhibits obvious pH and NIR-responsive release behaviour and the drug can be targetedly delivered to the cancer cells by a receptor mediated endocytosis manner. Furthermore, both photothermal therapy (PTT) and chemotherapy can be triggered simultaneously by a single 808 nm near infrared (NIR) light source, thus leading to a synergistic effect. The combined chemo- and NIR photothermal therapy can significantly improve the therapeutic efficacy compared to any single therapy, which has been evidenced by both in vitro and in vivo results. Besides, due to the doped rare earth ions, the platform also exhibits good up-conversion luminescence (UCL), computed tomography (CT) and magnetic resonance imaging (MRI) properties. Based on the excellent multimodal imaging and anti-tumor properties, the multifunctional nanoplatform should be a promising candidate for imaging-guided anti-cancer therapy.