[Response Characteristics of Soil Fungal Community Structure to Long-term Continuous Cropping of Pepper].

This study aimed to clarify the effect of long-term continuous cropping of pepper on soil fungal community structure, reveal the mechanism of continuous cropping obstacles, and provide a theoretical basis for the ecological safety and sustainable development of pepper industry. We took the pepper continuous cropping soil in the vegetable greenhouse planting base of Tongren City as the research object. The diversity and community structure of fungi in farmland soil were analyzed using Illumina MiSeq high-throughput sequencing, the responses of soil physio-chemical properties and fungal community characteristics to long-term continuous pepper cropping were discussed, and the relationships between the characteristics of fungal community structure and environmental factors were determined using CCA and correlation network analysis. The results showed that with the extension of pepper continuous cropping years, the soil pH value and organic matter (OM) content decreased, total phosphorus (TP) and available phosphorus (AP) contents increased, hydrolyzed nitrogen (AN) and available potassium (AK) contents decreased first and then increased, and total nitrogen (TN) and total potassium (TK) contents did not change significantly. Long-term continuous cropping decreased the Chao1 index and observed species index and decreased the Shannon index and Simpson index. The change in continuous cropping years had a significant effect on the relative abundance of soil fungal dominant flora. At the phylum level, the relative abundance of Mortierellomycota decreased with the extension of pepper continuous cropping years, the relative abundance of Ascomycota increased first and then decreased, and the relative abundance of Basidiomycota decreased first and then increased. At the genus level, with the increasing of pepper continuous cropping years, the relative abundance of Fusarium increased, and the relative abundance of Mortierella and Penicillium decreased. In addition, long-term continuous cropping simplified the soil fungal symbiosis network. CCA analysis indicated that pH, OM, TN, AN, AP, and AK were the driving factors of soil fungal community structure, and correlation network analysis showed that pH, OM, TN, TP, TK, AN, AP, and AK were the driving factors of soil fungal community structure, including Fusarium, Lophotrichus, Penicillium, Mortierella, Botryotrichum, Staphylotrichum, Plectosphaerella, and Acremonium. In conclusion, continuous cropping changed the soil physical and chemical properties, affected the diversity and community structure of the soil fungal community, changed the interaction between microorganisms, and destroyed the microecological balance of the soil, which might explain obstacles associated with continuous cropped pepper.

Genetic association between IL-27 rs153109 polymorphism and cancer risk in Chinese population: a meta-analysis.

IL-27 plays an important role in anti-cancer activity. The -964A/G polymorphism in IL-27 gene has been implicated in susceptibility to cancer, but the results were conflicting. The aim of this study was to assess the association between this polymorphism and cancer risk. Pubmed and Wanfang database were searched for all publications concerning IL-27 -964A/G polymorphism and cancer risk. Odds ratio (OR) and 95% confidence interval (CI) were used to assess the strength of association. Statistical analysis was performed using Stata 11.0 software. A total of eight case-control studies including 2044 cancer cases and 2197 controls were identified. Overall, significant association between IL-27 -964A/G polymorphism and cancer risk was observed (GG versus AA: OR = 1.26, 95% CI = 1.03-1.52; GG versus AG + AA: OR = 1.20, 95% CI = 1.00-1.44). In subgroup analysis based on cancer type, significant association was found in colorectal cancer (GG versus AA: OR = 1.55, 95% CI = 1.07-2.27; AG versus AA: OR = 1.31, 95% CI = 1.02-1.67). The current meta-analysis suggests that IL-27 -964A/G polymorphism might enhance cancer risk. However, large-scale and well-designed studies are still needed to confirm the result of our meta-analysis. The association of IL-27 polymorphism with colorectal cancer may provide insight for future therapies.

Fenofibrate induces G0/G1 phase arrest by modulating the PPARα/FoxO1/p27 kip pathway in human glioblastoma cells.

Fenofibrate, a fibric acid derivative, is known to possess lipid-lowering effects. Although fenofibrate-induced peroxisome proliferator-activated receptor alpha (PPARα) transcriptional activity has been reported to exhibit anticancer effects, the underlying mechanisms are poorly understood. In this study, we investigated the mechanisms behind the antiproliferative effects of fenofibrate in U87MG cells (human glioma cell line) using the WST-8 Cell Proliferation Assay Kit. Furthermore, we examined genome-wide gene expression profiles and molecular networks using the DAVID online software. Fenofibrate reduced the expression of 405 genes and increased the expression of 2280 genes. DAVID analysis suggested that fenofibrate significantly affected cell cycle progression and pathways involved in cancer, including the mTOR signaling pathway and insulin signaling pathway. Results of flow cytometry analysis indicated that fenofibrate induced cell cycle G0/G1 arrest in U87MG cells. Furthermore, we identified the FoxO1-p27(kip) signaling axis to be involved in fenofibrate-induced cell cycle arrest. Our findings suggest that in addition to its known lipid-lowering effects, fenofibrate may be used as an antitumor agent in glioma therapy.

MiR-143 acts as a tumor suppressor by targeting N-RAS and enhances temozolomide-induced apoptosis in glioma.

Therapeutic applications of microRNAs (miRNAs) in RAS-driven glioma were valuable, but their specific roles and functions have yet to be fully elucidated. Here, we firstly report that miR-143 directly targets the neuroblastoma RAS viral oncogene homolog (N-RAS) and functions as a tumor-suppressor in glioma. Overexpression of miR-143 decreased the expression of N-RAS, inhibited PI3K/AKT, MAPK/ERK signaling, and attenuated the accumulation of p65 in nucleus of glioma cells. In human clinical specimens, miR-143 was downregulated where an adverse with N-RAS expression was observed. Furthermore, overexpression of miR-143 decreased glioma cell migration, invasion, tube formation and slowed tumor growth and angiogenesis in a manner associated with N-RAS downregulation in vitro and in vivo. Finally, miR-143 also sensitizes glioma cells to temozolomide (TMZ),the first-line drug for glioma treatment. Taken together, for the first time, our results demonstrate that miR-143 plays a significant role in inactivating the RAS signaling pathway through the inhibition of N-RAS, which may provide a novel therapeutic strategy for treatment of glioma and other RAS-driven cancers.

Inhibition of activated Ras suppresses multiple oncogenic Hub genes in human epithelial tumors.

Cancer cells may involve diverse mutations, but they often rely on continued expression of a single oncoprotein for survival, as a response to targeting this protein. Generally, Ras is overexpressed in human epithelial tumors and cancellation of activated Ras inhibits carcinoma cell proliferation and differentiation ability, and induces apoptotosis of tumor cells. However, the mechanisms of inhibition of activated Ras that suppress the malignancy activity of human epithelial tumors remain to be illuminated. We utilized text-mining of MEDLINE abstracts with natural language processing to establish the Ras biologic association network, and identified several interactions of this network with the Ras pathway. Our investigation not only examined the expression of Ras and Hub genes (PIK3CA, MDM2, CCND1, EGFR, JUN, MYC, VEGFA, ERK1 and ERK2) but also confirmed inhibition of activated Ras reduced expression of multiple oncogene in vitro studies. Our studies provide strong support for the conclusion that cancellation of activated Ras specifically regulates defective Ras pathways in human tumor cells.

Overexpressed let-7a inhibits glioma cell malignancy by directly targeting K-ras, independently of PTEN.

BACKGROUND: Altered expression of micro(mi)RNAs has been shown to be associated with tumorigenesis and tumor progression. The expression of phosphatase and tensin homolog (PTEN) plays an important role in glioma and is regarded as a prognostic marker of glioma patients. The goal of this study was to investigate the function of lethal (let)-7a miRNA in glioma cell lines with different PTEN phenotypes. METHODS: One hundred ninety-eight glioma tissues were used to profile miRNA expression. RESULTS: Let-7a was shown to have lower expression in high-grade glioma than in low-grade glioma. Low expression of let-7a was correlated with poor prognosis of primary glioblastoma patients. We demonstrated that K-ras was a functional target for let-7a to induce cell cycle arrest, apoptosis, and inhibition of cell migration and invasion in vitro. Our further results showed no difference in malignancy inhibition induced by let-7a in 4 glioma cells, including U87 (PTEN null), U251 (PTEN mutant), LN229 (PTEN wild type), and LN229 (PTEN small interfering RNA). The phosphatidylinositol-3 kinase/Akt and mitogen-activated protein kinase/extracellular signal-regulated kinase pathways were inhibited by let-7a, and the inhibition effects had no difference in 4 glioma cells. We demonstrated that let-7a could induce suppression of glioma in vivo by generating a glioma xenograft model. CONCLUSION: Our results indicated that let-7a suppresses its target transcript K-ras and inhibits glioma malignancy independent of PTEN expression.

MiRNA-181b suppresses IGF-1R and functions as a tumor suppressor gene in gliomas.

MicroRNAs (miRNAs) are single-stranded, 18- to 23-nt RNA molecules that function as regulators of gene expression. Previous studies have shown that microRNAs play important roles in human cancers, including gliomas. Here, we found that expression levels of miR-181b were decreased in gliomas, and we identified IGF-1R as a novel direct target of miR-181b. MiR-181b overexpression inhibited cell proliferation, migration, invasion, and tumorigenesis by targeting IGF-1R and its downstream signaling pathways, PI3K/AKT and MAPK/ERK1/2. Overexpression of IGF-1R rescued the inhibitory effects of miR-181b. In clinical specimens, IGF-1R was overexpressed, and its protein levels were inversely correlated with miR-181b expression. Taken together, our results indicate that miR-181b functions in gliomas to suppress growth by targeting the IGF-1R oncogene and that miR-181b may serve as a novel therapeutic target for gliomas.

MiR-21 modulates hTERT through a STAT3-dependent manner on glioblastoma cell growth.

BACKGROUND AND PURPOSE: As an important oncogenic miRNA, miR-21 has been reported to play crucial roles in glioblastoma (GBM) carcinogenesis. However, the precise biological function and molecular mechanism of miR-21 in GBM remain elusive. This study is designed to explore the mechanism of miR-21 involved in the control of GBM cell growth. METHODS AND RESULTS: MTT assay, cell cycle analysis, and apoptosis analysis showed that reduction of miR-21 inhibited cell growth in U87 and LN229 GBM cells. Further, reduction of miR-21 decreased the expression of human telomerase reverse transcriptase (hTERT) and repressed STAT3 expression and STAT3 phosphorylation. STAT3 inhibition led to a remarkable depletion of hTERT at both mRNA and protein levels by binding to the hTERT gene promoter by performing luciferase reporter assay and chromatin Immunoprecipitation PCR. Finally, knockdown of miR-21 considerably inhibited tumor growth and diminished the expression of STAT3 and hTERT in xenograft model. CONCLUSION: Our findings indicate that miR-21 regulates hTERT expression mediated by STAT3, therefore controlling GBM cell growth.

MLH1 polymorphisms and cancer risk: a meta-analysis based on 33 case-control studies.

OBJECTIVE: Cumulative evidence suggests that MLH1, the key component in the mismatch pathway, plays an important role in human cancers. Two potential functional polymorphisms (-93G>A and I219V) of MLH1 have been implicated in cancer risk. The aim of this meta-analysis was to summarize the evidence for associations. METHODS: Eligible studies were identified by searching the electronic literature PubMed, ScienceDirect and Embase databases for relevant reports and bibliographies. Studies were included if of case-control design investigating MLH1 polymorphisms (-93G>A and I219V) and cancer risk with sufficient raw data for analysis. Odds ratios (OR) and 95% confidence intervals (95% CI) were used to evaluate the strength of associations. RESULTS: Our meta-analysis from 33 published case-control studies showed the variant A allele of -93G>A polymorphism to be associated with increased risk in all genetic models (AA vs. GG: OR = 1.22, 95% CI: 1.03-1.44), especially among non-Asians (AA vs. GG: OR = 1.28, 95% CI: 1.04-1.58). For the I219V polymorphism, however, there was no main effect associated with overall cancer risk in any genetic model. CONCLUSIONS: The meta-analysis suggested that the MLH1 -93G>A polymorphism may be a biomarker of cancer susceptibility. Large sample association studies and assessment of gene-to-gene as well as gene-to-environment interactions are required to confirm these findings.

[Expression of RAS protein in glioma and its effect on the growth of human glioma cells].

OBJECTIVE: To study the expression of RAS protein in human glioma tissues and its influence on tumor growth. METHODS: RAS protein expression in glioma tissues was determined by immunohistochemical (IHC) staining. Subsequently, MTT cell proliferation assay, flow cytometry and Western blotting were used to assay U251 cells with reduced RAS expression. RESULTS: The expression of RAS in glioma was increased and strongly correlated with pathological grade. Downregulation of RAS resulted in glioma cells growth suppression and increased apoptosis. CONCLUSION: The expression level of RAS protein in human glioma was increased. Downregulation of RAS can inhibit glioblastoma cell growth through the RAS signal pathway.

MiR-128 inhibits tumor growth and angiogenesis by targeting p70S6K1.

MicroRNAs are a class of small noncoding RNAs that function as critical gene regulators through targeting mRNAs for translational repression or degradation. In this study, we showed that miR-128 expression levels were decreased in glioma, and identified p70S6K1 as a novel direct target of miR-128. Overexpression of miR-128 suppressed p70S6K1 and its downstream signaling molecules such as HIF-1 and VEGF expression, and attenuated cell proliferation, tumor growth and angiogenesis. Forced expression of p70S6K1 can partly rescue the inhibitory effect of miR-128 in the cells. Taken together, these findings will shed light to the role and mechanism of miR-128 in regulating glioma tumor angiogenesis via miR-128/p70S6K1 axis, and miR-128 may serve as a potential therapeutic target in glioma in the future.

MiR-181d acts as a tumor suppressor in glioma by targeting K-ras and Bcl-2.

PURPOSE: Recently, several microRNAs (miRNAs) were reported to be involved in the modulation of glioma development. The aim of our study was to determine the effect of miR-181d on the growth of glioma and to investigate whether this growth is modulated by targeting K-ras and Bcl-2. METHODS: Real-time PCR was used to analyze the expression of miR-181d in human glioma samples and glioma cell lines. Apoptosis, cell cycle, and proliferation (MTT) assays were performed to assess the phenotypic changes in glioma cells. Immunohistochemistry was used to determine the expression of K-ras and Bcl-2 in glioma tissues, and a luciferase reporter assay was carried out to confirm whether K-ras and Bcl-2 are direct targets of miR-181d. Western blotting was used to identify the potential signaling pathways affected glioma cell growth by miR-181d. In vivo, xenograft tumors were examined for an anti-glioma effect of miR-181d. RESULTS: MiR-181d was down-regulated in human glioma samples and up-regulated in transfected glioma cells. Ectopic expression of miR-181d suppressed proliferation and triggered cell cycle arrest and apoptosis in glioma cell lines. K-ras and Bcl-2 were identified as direct targets of miR-181d and were up-regulated in glioma samples. The results showed evidence linking the tumor suppressor activity of miR-181d in glioma cells with the K-ras-related PI3K/AKT and MAPK/ERK pathways. Furthermore, xenograft tumors from miR-181d-treated U251 cells were suppressed in vivo. CONCLUSION: MiR-181d may act as a glioma suppressor by targeting K-ras and Bcl-2.

MicroRNA-7 regulates glioblastoma cell invasion via targeting focal adhesion kinase expression.

BACKGROUND: Invasion growth is the most characteristic biological phenotype of glioblastoma, but the molecular mechanism in glioma cell invasion is poorly understood. Recent data have showed that microRNA plays an essential role in tumor invasion. Our study aimed to explore the mechanism of miR-7 involved in the control of glioblastoma cell invasion. METHODS: Glioma cell invasion was evaluated by transwell and scratch assays after up-regulation of miR-7 using miR-7 mimics in U87 and U251 cells. Luciferase reporter assay was used to determine focal adhesion kinase (FAK) as a target of miR-7. The levels of miR-7, matrix metalloproteinases (MMP)-2 and MMP-9 mRNA were detected by PCR assay, and the levels of FAK, MMP-2, MMP-9, total and phosphorylation serine/threonine kinase (AKT), and extracellular signal-regulated kinase (ERK) 1/2 were measured by Western blotting analysis. RESULTS: Over-expression of miR-7 inhibited the invasion and migration activity of U87 and U251 cells. And up-regulation of miR-7 reduced FAK protein expression, Further, luciferase reporter assay showed that miR-7 modulated FAK expression directly by binding 3'UTR of FAK mRNA. In addition, miR-7 repressed p-ERK1/2 and p-AKT level, MMP-2 and MMP-9 expression. Finally, the inverse relationship between FAK and miR-7 expression was certificated in human glioma tissues. CONCLUSION: To our knowledge, these data indicate for the first time that miR-7 directly regulates cell invasion by targeting FAK in glioblastoma and that miR-7 could be a potential therapeutic target for glioblastoma intervention.