Malignant ascites supernatant enhances the proliferation of gastric cancer cells partially via the upregulation of asparagine synthetase.

Malignant ascites (MA) is a common manifestation of advanced gastric cancer (GC) with peritoneal metastasis (PM), which usually indicates a poor prognosis. The present study aimed to explore the effects of MA, a unique microenvironment of PM, on the proliferation of cancer cells and investigate the underlying mechanisms. Ex vivo experiments demonstrated that GC cells treated with MA exhibited enhanced proliferation. RNA sequencing indicated that asparagine synthetase (ASNS) was one of the differentially expressed genes in GC cells following incubation with MAs. Furthermore, the present study suggested that MA induced an upregulation of ASNS expression and the stimulatory effect of MA on cancer cell proliferation was alleviated upon ASNS downregulation. Activating transcription factor 4 (ATF4), a pivotal transcription factor regulating ASNS, was upregulated when cells were treated with MA supernatant. After ATF4 knockdown, the proliferation of MA-treated GC cells and the expression of ASNS decreased. In addition, the decline in the proliferation of the ATF4-downregulated AGS GC cell line was rescued by ASNS upregulation. The findings indicated that MA could promote the proliferation of GC cells via activation of the ATF4-ASNS axis. Hence, it may be a potential target for treating GC with PM and MA.

Liquid tumor microenvironment enhances WNT signaling pathway of peritoneal metastasis of gastric cancer.

Gastric cancer remains one of the most prevalent tumors worldwide and peritoneal metastasis is responsible for approximately 60% of death in advanced gastric cancer patients. However, the underlying mechanism of peritoneal metastasis is poorly understood. We have established organoids derived from malignant ascites (MA) of gastric cancer patients and noticed that MA supernatant could strongly increase the colony formation of organoids. Thus, we realized the interaction between exfoliated cancer cells (ECCs) and liquid tumor microenvironment contributes to peritoneal metastasis. Further, we designed a medium component control test which proved that exosomes derived from MA could not enhance the growth of organoids. Using Immunofluorescence and confocal imaging as well as dual-luciferase reporter assay, our data showed WNT signaling pathway was upregulated by high concentrations of WNT ligands (wnt3a and wnt5a), which was verified by ELISA. Besides, suppressing WNT signaling pathway diminished the growth promoting function of MA supernatant. This result implicated WNT signaling pathway as a potential therapeutic target for peritoneal metastasis of gastric cancer.

Bioinformatics Analysis Reveals the Vital Role of AKR1B1 in Immune Infiltration and Clinical Outcomes of Gastric Cancer.

Infiltrated immune cells are an important constitute of tumor microenvironment, which exert complex effects on gastric cancer (GC) pathogenesis and progression. By using weighted gene co-expression network analysis, integrating the data from The Cancer Genome Atlas-stomach adenocarcinoma and GSE62254, we identify Aldo-Keto Reductase Family 1 Member B (AKR1B1) as a hub gene for immune regulation in GC. Notably, AKR1B1 is associated with higher immune infiltration and worse histologic grade of GC. In addition, AKR1B1 is an independent factor for predicting the survival rate of GC patients. In vitro experiments further demonstrated that AKR1B1-overexpressed THP-1-derived macrophages promoted the proliferation and migration of GC cells. Taken together, AKR1B1 plays an important role in GC progression by regulating immune microenvironment, which could be a biomarker for predicting GC prognosis as well as a potential therapeutic target for GC treatment.

The effect of neoadjuvant chemotherapy on the tumor immune microenvironment in gastrointestinal tumors.

In recent years, numerous studies have demonstrated that the tumor immune microenvironment (TIME) is capable of regulating the growth of tumors, and tumor-infiltrating immune cells in the TIME can affect the prognosis and treatment responses of patients. Consequently, therapies targeting these immune cells have emerged as important antitumor treatments. As a crucial componet of the perioperative treatment of malignant tumors, neoadjuvant chemotherapy (NACT) can improve the surgical resection rate and prognosis of patients and is a suitable clinical model to evaluate the effect of chemotherapy on the TIME. To provide a rationale for developing valid combinational therapies, this review summarizes the impact of NACT on the TIME, the relationship between tumor-infiltrating immune cells and treatment responses of patients, and the prognostic value of these infiltrating immune cells.

Identification of N7-methylguanosine related subtypes and construction of prognostic model in gastric cancer.

Background: N7-methylguanosine (m7G), one of the most common post-transcriptional modifications, can be present in tRNA, mRNA, and miRNA to mediate the progression of various tumors. However, the possible role of m7G in gastric cancer (GC) is still unknown. Materials and Methods: In this study, SNVs (single nucleotide variations), CNVs (copy number variations), and methylation of m7G-related genes (m7GRGs) were analyzed. The relationship between them and the expression of m7GRGs and prognosis of GC patients was explored. Based on 13 prognostic-related m7GRGs, 567 GC samples were classified into three subtypes using the ConsensusClusterPlus package. we compared survival status, clinical traits, immune cell infiltration, immune checkpoints, tumor microenvironment (TME), tumor immune dysfunction and exclusion (TIDE), and potential biological pathways among the three subtypes. Then, patients were again grouped into different genetic subtypes based on the DEGs among the three subtypes. In addition, a prognostic m7GRG_Score was constructed using five risk genes applicable to patients of any age, gender and stage. We also assessed tumor mutational burden (TMB), microsatellite instability (MSI), cancer stem cell (CSC) index, sensitivity of antineoplastic drugs, efficacy of anti-PD-1 and anti-CTLA4 immunotherapy between high and low m7GRG_Score groups. Finally, we established a nomogram based on m7GRG_Score and tumor stage to enhance the clinical application of the model. miRNAs and lncRNAs that could regulate expression of risk genes were searched. Results: SNVs, CNVs, and methylation of m7GRGs were associated with m7GRGs expression. However, they did not significantly affect the survival of GC patients. Our results also confirmed that patients in subtypes B and C and low m7GRG_Score groups had longer survival time, better clinical stage, more immune cell infiltration, fewer immune escape and dysfunction compared to subtype A and high m7GRG_Score groups. A low m7GRG_score was featured with increased microsatellite instability-high (MSI-H), TMB, and efficacy of immunotherapy. Conclusion: The m7GRG_Score model may become a beneficial tool for predicting prognosis and guiding personalized treatment in GC patients. These findings will improve our knowledge of m7G in GC and provide new methods for more effective treatment strategies.

Application of natural killer cells in pancreatic cancer.

Pancreatic cancer, a highly malignant disease, is characterized by rapid progression and early metastasis. Although the integrative treatment of pancreatic cancer has made great progress, the prognosis of patients with advanced pancreatic cancer remains extremely poor. In recent years, with the advancements in tumor immunology, immunotherapy has become a promising remedy for pancreatic cancer. Natural killer (NK) cells are the key lymphocytes in the innate immune system. NK cell function does not require antigen pre-sensitization and is not major histocompatibility complex restricted. By targeting tumors or virus-infected cells, the cells play a key role in immune surveillance. Although several questions about NK cells in pancreatic cancer still need to be further studied, there are extensive theories supporting the clinical application prospects of NK cell immunotherapy in pancreatic cancer. Since very few studies have evaluated the role of NK cells in pancreatic cancer, this review provides a comprehensive update of the role of NK cells in pancreatic cancer immunotherapy.

Variations of electric potential in the xylem of tree trunks associated with water content rhythms.

Instantaneous electrical responses in plants have been widely studied, but the mechanism of spontaneous, periodic electric potential alternations in the xylem of tree trunks remains controversial. The generation of the electric potential can be explained by the electrode potential, which depends on ion concentrations near electrodes. However, several different hypotheses about its periodic variations have been proposed, including streaming potential, ion diffusion, charge transport, and oxygen turnover. Here, we performed long-term measurements on the electric potential and water content in the xylem of trees, and observed changes in the electric potential and transpiration rate in response to varied numbers of leaves, light radiation, temperature, and relative air humidity. The electric potential showed a distinct seasonal trend, combined with daily rhythms, and could be affected by environmental changes. Rapid changes in the electric potential routinely lagged behind those of the transpiration rate, but their ranges of change were proportional. Both annual and diurnal patterns of the electric potential were synchronous with the trees' water content. Moreover, we found potential function relationships between the electric potential and water content. Accordingly, we propose a new perspective, that the variations of the electric potential in tree xylem could be associated with water content rhythms.

Effects of Electrode Material on the Voltage of a Tree-Based Energy Generator.

The voltage between a standing tree and its surrounding soil is regarded as an innovative renewable energy source. This source is expected to provide a new power generation system for the low-power electrical equipment used in forestry. However, the voltage is weak, which has caused great difficulty in application. Consequently, the development of a method to increase the voltage is a key issue that must be addressed in this area of applied research. As the front-end component for energy harvesting, a metal electrode has a material effect on the level and stability of the voltage obtained. This study aimed to preliminarily ascertain the rules and mechanisms that underlie the effects of electrode material on voltage. Electrodes of different materials were used to measure the tree-source voltage, and the data were employed in a comparative analysis. The results indicate that the conductivity of the metal electrode significantly affects the contact resistance of the electrode-soil and electrode-trunk contact surfaces, thereby influencing the voltage level. The metal reactivity of the electrode has no significant effect on the voltage. However, passivation of the electrode materials markedly reduces the voltage. Suitable electrode materials are demonstrated and recommended.

Calcium/calmodulin-dependent protein kinase II (CaMKII), through NMDA receptors and L-Voltage-gated channels, modulates the serine phosphorylation of GluR6 during cerebral ischemia and early reperfusion period in rat hippocampus.

Recent studies have shown that GluR6 is involved in the modulation of neuronal cell death. It has been shown that PKA can phosphorylate recombinant GluR6 homomeric receptors and that this phosphorylation of GluR6 was suggested to underlie an enhancement of whole-cell current responses. Here, we try to find out whether brain ischemia and reperfusion could induce any change in the serine phosphorylation of GluR6. Our results showed that the serine phosphorylation of GluR6 increased in hippocampus during brain ischemia and early reperfusion period. Then, we used several drugs to investigate the mechanism of modulating the serine phosphorylation of GluR6. KT5720, a specific cell-permeable inhibitor of protein kinase A (PKA), had no effect on the increase in serine phosphorylation of GluR6 induced by brain ischemia or reperfusion. On the other hand, KN-62, a selective inhibitor of rat brain Ca(2+)/calmodulin-dependent protein kinase II (CaMKII), diminished the increase in serine phosphorylation of GluR6. Moreover, our results showed that either MK801 (a NMDA receptor antagonist) or Nifedipine (a L-type Ca2+ channel (L-VGCC) blocker) decreased the increase in serine phosphorylation. In conclusion, our results suggest that CaMKII, activated through NMDA receptors and L-VGCCs, mediated the serine phosphorylation of GluR6 during brain ischemia and early reperfusion period.

The neuroprotective action of SP600125, a new inhibitor of JNK, on transient brain ischemia/reperfusion-induced neuronal death in rat hippocampal CA1 via nuclear and non-nuclear pathways.

Increasing evidence suggests that c-Jun N-terminal kinase (JNK) is an important kinase mediating neuronal apoptosis in brain ischemia. To further study the roles of JNK activation in hippocampal CA1 neurons in a rat model of transient global ischemia, we assessed the effect of JNK inhibition by SP600125 on the degree of brain injury. Our results demonstrated that SP600125 significantly increased the number of surviving cells in hippocampal CA1 subfield and decreased the activation of p-JNK1/2 and p-JNK3 at 30 min and 3 days after brain ischemia. Moreover, SP600125 significantly diminished the increased levels of phosphorylated-c-Jun (Ser63/73) and phosphorylated-Bcl-2 (Ser87) at 3 h after brain ischemia. These results indicate that SP600125, a new inhibitor of JNK, protected transient brain ischemia/reperfusion-induced neuronal death in rat hippocampal CA1 region at least via suppressing the activation of nuclear substrate (c-Jun) and inactivating non-nuclear substrate (Bcl-2) induced by ischemic insult. Thus, inhibiting JNK activity by SP600125 may represent a new and effective strategy to treat ischemic stoke.

Postsynaptic density protein 95 antisense oligodeoxynucleotides inhibits the activation of MLK3 and JNK3 via the GluR6.PSD-95.MLK3 signaling module after transient cerebral ischemia in rat hippocampus.

In this study, we investigated the effect of PSD-95 antisense oligodeoxynucleotides on the phosphorylation of MLK3, JNK3 and interactions of MLK3 and PSD-95 with kainate receptor (GluR6) by immunoprecipitation and immunoblotting. Transient (15 min) brain ischemia was induced by the four-vessel occlusion in Sprague-Dawley rats. The antisense oligodeoxynucleotides of PSD-95 were administrated to the SD rats once per day for 3 days before ischemia. Our data show that the antisense oligodeoxynucleotides could inhibit phosphorylation of MLK3 and JNK3 and decrease the interactions of MLK3 and PSD-95 with GluR6. These results indicate that PSD-95 plays an important role in the formation of the GluR6.PSD-95.MLK3 signaling module and MLK3 and JNK3 activation in postischemic rat hippocampus.

Lithium suppressed Tyr-402 phosphorylation of proline-rich tyrosine kinase (Pyk2) and interactions of Pyk2 and PSD-95 with NR2A in rat hippocampus following cerebral ischemia.

It has been indicated that Pyk2/Src signaling pathway is involved in modulation of N-methyl-D-aspartate-type (NMDA) glutamate receptor activity. Lithium protects against glutamate-induced excitotoxicity in cultured neurons and in animal models of diseases. The neuroprotection against excitotoxicity afforded by lithium is time-dependent, requiring treatment for 6-7 days for maximal effect. In this study, we examined the time-course and the effect of lithium on Tyr-402 phosphorylation of Pyk2 and Tyr-416 phosphorylation of Src as well as the association of Pyk2 and NMDA receptor subunit 2A (NR2A) mediated by postsynaptic density protein 95 kDa (PSD-95) in the condition of cerebral ischemia, which was induced by occlusion of the four vessels in Sprague-Dawley rats. At 6 h of reperfusion following 15 min of ischemia (I/R), the effects induced by chronic lithium were observed, including the decrease in enhanced Tyr-402 phosphorylation of Pyk2, the inhibition in increased Tyr-416 phosphorylation of Src and the attenuation in enhanced interactions of Pyk2 and PSD-95 with NR2A. Our results further suggest that the activated Pyk2 potentiates NMDA receptor function during transient brain ischemia followed by reperfusion and the above inhibition induced by lithium is likely to result in the inactivation of NMDA receptor and contributes to the neuroprotection against excitotoxicity.