MicroRNA 32 promotes cell proliferation,migration, and suppresses apoptosis in colon cancer cells by targeting OTU domain containing 3

Colorectal cancer is considered as the fourth leading reason of cancer-linked deaths worldwide. However, our knowledge about its pathogenic mechanism remains inadequate. MicroRNA 32 (miR-32), a member of small noncoding RNAs, has been found vital roles in tumorigenesis. This study studied its functions and underlying mechanism in colorectal cancer. The experiment revealed the obvious upregulation of miR-32 in colorectal cancer tissues and six cancer cell lines, compared with normal tissues and cells. Moreover, miR-32 upregulation reduced cell apoptosis and promoted cell proliferation and migration, while its downregulation displayed opposite effects. Dual luciferase reporter assays proved that miR-32 bound to the 3′-untranslated region (3′-UTR) of OTU domain containing 3 (OTUD3), suggesting that miR-32 directly targeted OTUD3. Further experiments demonstrated that overexpression of miR-32 could reduce the expression level of OTUD3. Furthermore, OTUD3 silence promoted proliferation and motility and decreased apoptosis for HCT116 cells and restored partly miR-32-mediated cell proliferation, migration, and antiapoptosis for colon cancer. Therefore, our study indicated that miR-32 enhanced cell proliferation and motility abilities, and inhibited apoptosis by directly targeting OTUD3 in colon cancer cells, which implied that miR-32 was hopeful to be a biomarker or target used for diagnosis and therapy of colon cancer.     

Asymmetric dimethylarginine targets MAPK pathway to regulate insulin resistance in liver by activating inflammation factors

Insulin resistance is associated with impaired glucose uptake and altered protein kinase B (Akt) signaling. Previous studies have suggested asymmetric dimethylarginine (ADMA) and inflammation are two distinguish factors that correlate with insulin resistance (IR). How ADMA and inflammation factors interact and synchronize in the regulation of IR in liver remain to be elucidated. In this study, we systematically investigated whether ADMA is involved in IR using primary hepatocytes, if yes, by via which molecular mechanism. Our results demonstrated that ADMA inhibits insulin sensitivity in a concentration-dependent manner by activating inflammation factors tumor necrosis factor (TNF)-α, interleukin (IL)-1, and IL-6 in primary hepatocytes. Further analysis revealed that mitogen-activated protein kinase (MAPK) signaling pathway act downstream of ADMA and inflammation factors, and inhibition of MAPK pathway rescued the IR. Furthermore, metformin effects has been found which could reverse ADMA-induced IR by suppressing MAPK signaling pathway. To our knowledge, we, for the first time, unveiled the complicated regulatory network and interactions among ADMA, inflammation, and MAPK signaling pathway, which advanced current research on the development and regulation of IR in liver. This study also certainly provided novel insights on comprehensive diagonistics roles of ADMA as a potential biomarker.     

Promotion of PTEN on apoptosis through PI3K/Akt signal in vascular smooth muscle cells of mice model of coronary heart disease

Previous studies have shown that phosphatase and tensin homolog (PTEN) are key regulators of the development of many malignant tumors and other diseases. However, its regulatory effect on coronary heart disease (CHD) has rarely been reported. Therefore, the regulatory effect of PTEN on the survival and cell death of vascular smooth muscle cells (VSMCs) in CHD mice was elucidated in this study. It was found that the protein and messenger RNA expressions of PTEN in VSMCs of 10 CHD mice were lower than those of normal mice. Then PTEN was overexpressed in VSMCs. It was suggested that the upregulation of PTEN was not conducive to the proliferation and survival of VSMCs in the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and colony formation assay. The flow cytometry (Annexin V-Fluorescein isothiocyanate (FITC)/propidium iodide) and the terminal deoxynucleotidyl transferase dUTP nick end labeling assay were used to detect the apoptotic rate of overexpressing PTEN cells. Some data showed that the expression of PTEN could lead to increased apoptotic rate. It was shown that antiapoptotic Bcl-2 levels were decreased, but cleaved caspase-3 and proapoptotic Bax levels were promoted by SIRT6 overexpression in Western blot analysis. Moreover, PI3K/Akt expression and phosphorylation were significantly decreased in cells expressing PTEN. Recovery of PI3K expression inhibited the suppressive influence of PTEN on VSMC survival, as evidenced by the activated PI3K/Akt pathway, increased cell proliferative rate, reduced the apoptotic level, and reversed expression patterns of Bcl-2 and Bax. Therefore, the findings in this study provide a new idea on the occurrence and development mechanism of CHD and may promote the discovery of innovative therapies.     

Long noncoding RNA MALAT-1 inhibits apoptosis and matrix metabolism disorder in interleukin-1β-induced inflammation in articular chondrocytes via the JNK signaling pathway

Proinflammatory cytokine such as interleukin (IL)-1β causes inflammation of articular cartilage. In this current study, we explored the chondroprotective effects of long noncoding RNA (lncRNA) MALAT-1 on cell proliferation, apoptosis, and matrix metabolism in IL-1β-induced inflammation in articular chondrocytes. Articular chondrocytes from knee joints of normal rats were isolated and cultured, followed by identification through observation of toluidine blue and COL II immunocytochemical stainings. The proliferation of chondrocytes at passage 2 was detected by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. The inflammatory chondrocytes induced by 10 ng/mL IL-1β were observed and identified by toluidine blue and COL II immunocytochemical stainings. pcDNA 3.1 and pcDNA-MALAT-1 were transfected in the chondrocytes. Ultrastructure of chondrocytes was observed by using a transmission electron microscope. The MTT assay was carried out to evaluate chondrocyte viability. Hoechst 33258 staining and flow cytometry were adopted to assess chondrocyte apoptosis. The chondrocytes at passage 2 with the biological characteristics of chondrocytes were used for subsequent experiments. In IL-1β-treated chondrocytes, the growth rate of chondrocytes slowed down, the cells became narrow and long, the vacuoles were seen in the cells, and the morphology of the chondrocytes was irregular. The toluidine blue staining and the immunohistochemical staining of COL II became weaker. In response to IL-1β induction, articular chondrocytes showed reduced MALAT-1 expression; moreover, obvious cartilage injury was observed with decreased chondrocyte viability and Col II expression and elevated chondrocyte apoptosis, MMP-13 expression, and p-JNK expression. With the treatment of pcDNA-MALAT-1, the cartilage injury was alleviated with increased chondrocyte viability and type II collagen (Col II) expression and reduced chondrocyte apoptosis, MMP-13 expression and p-JNK expression. Taken together these results, lncRNA MALAT-1 blocked the activation of the JNK signaling pathway; thereby, IL-1β-induced inflammation in articular chondrocytes was reduced with enhanced chondrocyte proliferation and suppressed chondrocyte apoptosis and extracellular matrix degradation.     

Erlotinib inhibits colon cancer metastasis through inactivation of TrkB-dependent ERK signaling pathway

The distal metastasis is the main cause of death in patients with colon cancer. Tyrosine receptor kinase B (TrkB) and ERK signals may be the potential targets for the treatment of colon cancer metastasis. This study aims to investigate whether erlotinib inhibits distant metastasis of colon cancer by regulating TrkB and ERK signaling pathway. Human colon adenocarcinoma cell lines (SW480 and Caco-2) pretreated with exogenous C-X-C motif chemokine ligand 8 (CXCL8) were used to assess the suppressive effect of erlotinib on tumor metastasis, including anoikis, epithelial-mesenchymal transformation (EMT), migration, and invasion. Through TrkB overexpression, Akt suppression, and ERK suppression, the roles of TrkB, Akt, and ERK in erlotinib-induced metastasis inhibition of colon cancer cells were explored. The results showed that erlotinib alleviated CXCL8-induced metastasis of the colon cancer cells. Overexpression of TrkB in colon cancer cells eliminated the effect of erlotinib on anoikis, inhibition of EMT, migration, and invasion, and downregulation of p-ERK and p-Akt. Furthermore, the inhibition of ERK activation instead of Akt activation was found to participate in erlotinib-mediated metastasis resistance, including anoikis, inhibition of EMT, migration, and invasion. In conclusion, erlotinib inhibits colon cancer cell anoikis resistance, EMT, migration, and invasion by inactivating TrkB-dependent ERK signaling pathway.     

Improving the Genome Annotation of Rhizoctonia solani Using Proteogenomics

Background Rhizoctonia solani is a pathogenic fungus that causes serious diseases in many crops, including rice, wheat, and soybeans. In crop production, it is very important to understand the pathogenicity of this fungus, which is still elusive. It might be helpful to comprehensively understand its genomic information using different genome annotation strategies.MethodsAiming to improve the genome annotation of R. solani, we performed a proteogenomic study based on the existing data. Based on our study, a total of 1060 newly identified genes, 36 revised genes, 139 single amino acid variants (SAAVs), 8 alternative splicing genes, and diverse post-translational modifications (PTMs) events were identified in R. solani AG3. Further functional annotation on these 1060 newly identified genes was performed through homology analysis with its 5 closest relative fungi.ResultsBased on this, 2 novel candidate pathogenic genes, which might be associated with pathogen-host interaction, were discovered. In addition, in order to increase the reliability and novelty of the newly identified genes in R. solani AG3, 1060 newly identified genes were compared with the newly published available R. solani genome sequences of AG1, AG2, AG4, AG5, AG6, and AG8. There are 490 homologous sequences. We combined the proteogenomic results with the genome alignment results and finally identified 570 novel genes in R. solani.ConclusionThese findings extended R. solani genome annotation and provided a wealth of resources for research on R. solani.     

Nonalternating purine pyrimidine sequences can form stable left-handed DNA duplex by strong topological constraint

In vivo, left-handed DNA duplex (usually refers to Z-DNA) is mainly formed in the region of DNA with alternating purine pyrimidine (APP) sequence and plays significant biological roles. It is well known that d(CG)_n sequence can form Z-DNA most easily under negative supercoil conditions, but its essence has not been well clarified. The study on sequence dependence of Z-DNA stability is very difficult without modification or inducers. Here, by the strong topological constraint caused by hybridization of two complementary short circular ssDNAs, left-handed duplex part was generated for various sequences, and their characteristics were investigated by using gel-shift after binding to specific proteins, CD and T_m analysis, and restriction enzyme cleavage. Under the strong topological constraint, non-APP sequences can also form left-handed DNA duplex as stable as that of APP sequences. As compared with non-APP sequences, the thermal stability difference for APP sequences between Z-form and B-form is smaller, which may be the reason that Z-DNA forms preferentially for APP ones. This result can help us to understand why nature selected APP sequences to regulate gene expression by transient Z-DNA formation, as well as why polymer with chirality can usually form both duplexes with left- or right-handed helix.