Pazopanib stimulates senescence of renal carcinoma cells through targeting nuclear factor E2-related factor 2 (Nrf2).

Renal cell carcinoma (RCC) is the most common kidney cancer with high mortality rate. Pazopanib has been approved for the treatment of RCC. However, the underlying mechanism is not clear. Here, we report a novel finding by showing that treatment with Pazopanib could promote cellular senescence of the human RCC cell line ACHN. Cells were stimulated with 5, 10, and 20 µM Pazopanib, respectively. Cellular senescence was measured using senescence-associated ß-galactosidase (SA-ß-Gal) staining. Western blot analysis and real-time polymerase chain reaction were used to measure the mRNA and protein expression of nuclear factor E2-related factor 2 (Nrf2), γH2AX, human telomerase reverse transcriptase (hTERT), telomeric repeat binding factor 2 (TERF2), p53 and plasminogen activator inhibitor (PAI). First, we found that exposure to Pazopanib reduced the cell viability of ACHN cells. Additionally, Pazopanib induced oxidative stress  by increasing the production of reactive oxygen species, reducing the levels of glutathione peroxidase, and promoting nuclear translocation of Nrf2. Interestingly, Pazopanib exposure resulted in DNA damage by increasing the expression of γH2AX. Importantly, Pazopanib increased cellular senescence and reduced telomerase activity. Pazopanib also reduced the gene expression of hTERT but increased the gene expression of TERF2. Correspondingly, we found that Pazopanib increased the expression of p53 and PAI at both the mRNA and protein levels. To elucidate the underlying mechanism, the expression of Nrf2 was knocked down by transduction with Ad- Nrf2 shRNA. Results indicate that silencing of Nrf2 in ACHN cells abolished the effects of Pazopanib in stimulating cellular senescence and reducing telomerase activity. Consistently, knockdown of Nrf2 restored the expression of p53 and PAI in ACHN cells. Based on these results, we explored a novel mechanism whereby which Pazopanib displays a cytotoxicity effect in RCC cells through promoting cellular senescence mediated by Nrf2.

Organic fertilizer substitutions maintain maize yield and mitigate ammonia emissions but increase nitrous oxide emissions.

Organic fertilizer can improve soil structure and enhance the nutrient content in soil and is beneficial to sustainable agricultural development. However, the influence of organic fertilizer substitutions on NH3 and N2O emissions from farmland is unclear. Thus, we set up an organic substitution field experiment in Northeast China. The experiment included six treatments: single application of chemical fertilizers (NPK: 250 kg N ha-1); NO10, 10% reduction in chemical nitrogen fertilizers (225 kg N ha-1) + chicken manure (25 kg N ha-1); NO20, 20% reduction in chemical nitrogen fertilizers (200 kg N ha-1) + chicken manure (50 kg N ha-1); NO30, 30% reduction in chemical nitrogen fertilizers (175 kg N ha-1) + chicken manure (75 kg N ha-1); NO40, 40% reduction in chemical nitrogen fertilizers (150 kg N ha-1) + chicken manure (100 kg N ha-1); and no-nitrogen fertilizer (CK). This experiment investigated the effects of partial substitution of chemical nitrogen fertilizer with organic fertilizer on NH3 and N2O emissions and nitrogen use efficiency in a maize field. The results showed that, compared with chemical N, organic fertilizer mitigated NH3 volatilization but promoted the soil N2O total emissions during the whole growth stage. NH3 cumulative volatilization decreased with the increase in the substitution rate of organic fertilizer. Compared with the NPK treatment, the cumulative volatilization of NH3 in the NO30 and NO40 treatments decreased by 15.24 and 17.92%, respectively. The NO40 treatment had the highest N2O emission in the whole growth stage, and the N2O emission of the NO40 treatment increased by 10.72% compared to the NPK treatment. Moreover, the yield, partial factor productivity (PFP), nitrogen harvest index (NHI), and apparent nitrogen recovery efficiency (NRE) of NO30 treatment were the highest of all treatments, and the yields, PFP, plant N accumulation, grain N accumulation, and the cumulative emissions of NH3 and N2O were similar to N20 treatment. In conclusion, nitrogen fertilizer use efficiency was enhanced, decreasing environmental pollution from livestock under organic fertilizer substitution conditions. We suggested 20% or 30% substitution rates of organic fertilizer were proper.

Single-cell characterization revealed hypoxia-induced metabolic reprogramming of gastric cancer.

Introduction: Gastric cancer (GC) is one of the most common malignant tumors worldwide. Single-cell sequencing technology can achieve an accurate and unbiased assessment of cell heterogeneity. Therefore, it is necessary to explore the molecular characteristics of GC-related malignant cells at a single-cell resolution. Methods: Single-cell RNA sequencing GC profiles were collected from the Gene Expression Omnibus database. Moreover, feature gene sets of metabolic pathways and hypoxia signals were collected from the Molecular Signatures Database. The marker genes of specific cell types were collected from the published literature and CellMarker database. The R package InferCNV was used to calculate the copy-number variations of cells and to identify real cancer cells. The weighted relative pathway activity algorithm was used to evaluate the differences in metabolic activity between cell types. Results: Our study found that cancer epithelial cells exhibited individual differences in molecular features and showed metabolic heterogeneity. Oxidative phosphorylation and glycolytic pathway activity were the major contributors to the metabolic heterogeneity of cancer epithelial cells. Furthermore, we used the hypoxia signaling pathway to indirectly evaluate the oxygen content of cells and found that hypoxia contributed to the heterogeneity of cancer epithelial cells. Finally, functional identification of genes co-expressed with HIF1A showed that the reprogramming of the oxidative stress response contributed to the tumor malignant progression. Conclusions: This study described hypoxia-induced metabolic reprogramming of GC at a single-cell level, partially addressing the lack of insight into the heterogeneity of cancer cell metabolism when using traditional sequencing technology.

Epigenetic modification facilitates proline synthase PYCR1 aberrant expression in gastric cancer.

BACKGROUND & AIMS: Pyrroline-5-carboxylate reductase 1 (PYCR1) upregulation contributes to the progression of gastric cancer (GC) and indicates poor survival. However, PYCR1 expression profile in GC subtypes and the mechanism behind its upregulation are not well-studied. METHODS: PYCR1 expression profiles in GC subtypes and different stages of gastric carcinogenesis were assessed in different GC cohorts. Genetic alterations and epigenetic modulation in PYCR1 regulation were further investigated using bioinformatics analysis and in vitro experiments. RESULTS: PYCR1 expression was significantly higher in intestinal-type GC and associated molecular subtypes in TCGA and ACRG GC cohorts. During the cascade of intestinal-type GC, PYCR1 was continuously increased from normal gastric tissues through to atrophic gastritis, to intraepithelial neoplasia, and to GC. Copy number alterations in PYCR1 were associated with PYCR1 transcript expression. One CpG island was observed in PYCR1 promoter region, and the hypomethylation occurred at this region could contribute to PYCR1 transcriptional activation in GC. Besides, H3K27ac combination was found in PYCR1 promoter, and acetyltransferase p300 induced H3K27ac could promote PYCR1 expression in GC. CONCLUSIONS: PYCR1 expression varies across GC subtypes, with intestinal-type GC and associated molecular subtypes having the highest expression. Hypomethylation at CpG sites and p300-induced H3K27ac modification within PYCR1 promoter could contribute to maintaining PYCR1 overexpression in GC. These results provide us with a new insight into epigenetic modulation in mitochondrial proline metabolism.

The necessity and appropriate range of the diagnostic "gray zone" of 13C-urea breath test.

Background: The 13C-urea breath test (13C-UBT) is preferred for non-invasive detection of Helicobacter pylori (H. pylori); however, its accuracy drops when results fall between 2‰ and 6‰ (called the gray zone). This study aimed to evaluate the accuracy of 13C-UBT (cut-off point 4‰) between 2‰ and 6‰, find a more appropriate gray zone, and identify the factors influencing 13C-UBT. Methods: Patients with 13C-UBT results 2‰-6‰, over an eight-year period, were studied. H. pylori infection was diagnosed if patients were positive for either Warthin-Starry staining or quantitative real-time polymerase chain reaction (real-time PCR), and excluded if both were negative. Accuracy of 13C-UBT under different cut-off points was calculated, and the factors affecting 13C-UBT were analyzed. Results: A total of 208 patients were included, of whom 129 were H. pylori-positive. Sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of 13C-UBT were 71.32%, 83.54%, 64.08%, and 87.62%, respectively. When the cut-off point was changed to 2.15‰, the NPV of 13C-UBT reached a maximum (76.47%); when the cut-off point was changed to 4.95‰, PPV reached its maximum (93.22%). Therefore, the original gray zone (2‰-6‰) was adjusted to 2‰-4.95‰. Gastric antral intestinal metaplasia (OR = 3.055, 95% CI: 1.003-9.309) was an independent risk factor for false-negative 13C-UBT. Conclusions: Accuracy of 13C-UBT over 2‰-6‰ was poor, and the gray zone was changed to 2‰-4.95‰. 13C-UBT results over 2‰-4.95‰ should be interpreted with caution during mass screening of H. pylori, especially for patients with gastric antral intestinal metaplasia.

Long-Term Outcome of Gastric Mild-Moderate Dysplasia: A Real-World Clinical Experience.

BACKGROUND & AIMS: The natural course of gastric mild-moderate dysplasia in a country with high incidence of gastric cancer (GC) is relatively unknown. We aimed to determine the long-term cumulative incidence of and risk factors for advanced neoplasia in patients with gastric dysplasia. METHODS: This was a single-center observational study including all consecutive patients diagnosed with gastric mild-moderate dysplasia between 2000 and 2017. Follow-up data were collected until December 2019. We determined the cumulative incidence of advanced neoplasia and identified risk factors with Cox regression. RESULTS: A total of 3489 consecutive participants were followed for a median of 4.19 years from initial mild-moderate dysplasia diagnosis. The median surveillance interval between index endoscopy and next follow-up endoscopy was 1.08 years, and more than half of patients had at least 3 surveillance gastroscopies. During the study period, the majority of participants did not show disease progression, either with dysplasia not detected (51.4%) or with persistent dysplasia (46.1%). There were 88 (2.9%) patients (5.13 per 1000 patient-years) who progressed to advanced neoplasia within a median of 4.3 years. The annual incidence of advanced neoplasia and GC were 0.43% and 0.26%, respectively, within 5 years of mild-moderate dysplasia diagnosis. Increasing age, male sex, moderate dysplasia, dysplasia detected in fundus or cardia at index endoscopy, and persistent Helicobacter pylori infection during follow-up were independent risk factors for developing advanced neoplasia. CONCLUSIONS: Even in a country with high incidence of GC, the majority of patients with gastric mild-moderate dysplasia did not experience disease progression in the long term. Intensified surveillance during the first 5 years after mild-moderate dysplasia detection is suggested.

The impact of Helicobacter pylori infection, eradication therapy, and probiotics intervention on gastric microbiota in young adults.

BACKGROUND: The impact of probiotics on non-Helicobacter pylori gastric microbiota and its role in microbial restoration after eradication were relatively unknown. We aimed to explore the effect of H. pylori eradication and probiotic intervention on gastric microbiota in young adults. METHODS: Fifty-six H. pylori-negative and 95 H. pylori-positive subjects aged 19-30 were included in this study. H. pylori-infected individuals were randomly assigned to quadruple therapy, probiotics supplemented quadruple therapy, or probiotics monotherapy group. Gastric mucosa and gastric juice samples were collected before and 2 months after treatment for 16SrRNA gene sequencing. RESULTS: The gastric microbial community structure and composition differed from H. pylori-negative subjects 2 months after successful H. pylori eradication. The α diversity of gastric mucosal microbiota significantly increased and was higher than H. pylori-negative subjects, while the α diversity of gastric juice microbiota decreased and was lower than the H. pylori-negative. After probiotics supplemented eradication treatment, Bifidobacterium was enriched in gastric mucosa, Lactobacillus was enriched in gastric juice, potentially pathogenic bacteria such as Fusobacterium and Campylobacter decreased, and the microbial diversity was closer to that of H. pylori-negative subjects compared to quadruple therapy group. Probiotics monotherapy significantly altered the diversity, community structure, and composition of gastric microbiota but showed no advantage in H. pylori inhibition and upregulating beneficial bacteria such as Bifidobacterium and Lactobacillus and related metabolism pathways. Certain potentially pathogenic bacteria such as Fusobacterium increased after probiotic monotherapy. CONCLUSION: H. pylori eradication significantly disrupted gastric microbiota in young adults and could not be restored in a short time. Probiotics supplementation partially helped restore the gastric dysbiosis caused by eradication therapy, but it might be unnecessary for H. pylori-infected young adults to take probiotics alone.

Endoscopic grading of gastric atrophy on risk assessment of gastric neoplasia: A systematic review and meta-analysis.

BACKGROUND AND AIM: Endoscopic examination of gastric atrophy has been developed to determine the extent of atrophy by identifying the atrophic border of gastric mucosa, but its value in predicting the risk of developing gastric neoplasms is not quantified. Thus, this systematic review and meta-analysis aim to assess the incidence risk of gastric neoplasms on the basis of endoscopic grading of gastric atrophy. METHODS: Two authors independently searched the electronic databases (PubMed, Embase, and the Cochrane Library) from inception through December 31, 2019, without language restriction. The effect size on study outcomes is calculated using random-effects model and presented as risk ratio (RR) with 95% confidence interval (CI). Heterogeneity, publication bias, and quality of included studies were also assessed. RESULTS: Fourteen retrospective studies are identified to perform systematic review and meta-analysis, 11 were cohort studies, and three were cross-sectional research. The pooled RR for developing gastric neoplasms is 3.89 (95% CI 2.92-5.17) among general patients with severe endoscopic atrophy. For patients who underwent endoscopic resection for early gastric neoplasms, nearly two times increased risk of synchronous or metachronous neoplasms is pooled (RR = 1.96, 95% CI 1.39-2.75). In terms of the type of endoscopic atrophy, patients with open-type endoscopic atrophy have a higher risk of gastric cancer development (RR 8.02; 95% CI 2.39-26.88) than those with close type. [Correction added on 22 December 2020, after first online publication: '(RR = 7.27; 95% CI 1.64-32.33)' has been corrected to '(RR 8.02; 95% CI 2.39-26.88)'] CONCLUSIONS: Grading endoscopic atrophy according to the Kimura-Takemoto classification can assess the risk of gastric neoplasia development. Patients with severe or open-type endoscopic gastric atrophy at baseline should undergo rigorous surveillance to early detect premalignant lesions and cancer.

Ionosphere-Constrained Single-Frequency PPP with an Android Smartphone and Assessment of GNSS Observations.

With the development of Global Navigation Satellite System (GNSS) and the opening of Application Programming Interface (API) of Android terminals, the positioning research of Android terminals has attracted the attention of GNSS community. In this paper, three static experiments were conducted to analyze the raw GNSS observations quality and positioning performances of the smartphones. For the two experimental smartphones, the numbers of visible satellites with dual-frequency signals are unstable and not enough for dual-frequency Precise Point Positioning (PPP) processing all through the day. Therefore, the ionosphere-constrained single-frequency PPP model was employed to improve the positioning with the smartphones, and its performance was evaluated and compared with those of the Single Point Positioning (SPP) and the traditional PPP models. The results show that horizontal positioning accuracies of the smartphones with the improved PPP model are better than 1 m, while those with the SPP and the traditional PPP models are about 2 m.

11.5% efficiency of TiO2 protected and Pt catalyzed n+np+-Si photocathodes for photoelectrochemical water splitting: manipulating the Pt distribution and Pt/Si contact.

A combination of hydrogen passivation, electroless deposition of a Pt catalyst and coating a TiO2 protective layer leads to an unprecedented 11.5% energy conversion efficiency and one-week stability of an n+np+-Si photocathode for solar water splitting.

Efficient and Stable Silicon Photocathodes Coated with Vertically Standing Nano-MoS2 Films for Solar Hydrogen Production.

Water splitting in a photoelectrochemical cell, which converts sunlight into hydrogen energy, has recently received intense research. Silicon is suitable as a viable light-harvesting material for constructing such cell; however, there is a need to improve its stability and explore a cheap and efficient cocatalyst. Here we fabricate highly efficient and stable photocathodes by integrating crystalline MoS2 catalyst with ∼2 nm Al2O3 protected n+p-Si. Al2O3 acts as a protective and passivative layer of the Si surface, while the sputtering method using a MoS2 target along with a postannealing leads to a vertically standing, conformal, and crystalline nano-MoS2 layer on Al2O3/n+p-Si photocathode. Efficient (0.4 V vs RHE onset potential and 35.6 mA/cm2 saturated photocurrent measured under 100 mA/cm2 Xe lamp illumination) and stable (above 120 h continuous water splitting) photocathode was obtained, which opens the door for the MoS2 catalyst to be applied in photoelectrochemical hydrogen evolution in a facile and scalable way.