Transcriptional factor CCAAT enhancer binding protein beta inhibits epithelial-mesenchymal transition in cervical cancer via regulating attractin-like 1.

Cervical cancer (CC) is a malignancy seriously endangering women's life and health worldwide. GEPIA demonstrated that attractin-like 1 (ATRNL1) presents downregulation in CC tissue. Transcription factor CCAAT enhancer binding protein beta (CEBPB) was previously revealed to present depletion in CC tissue. We attempted to clarify molecular mechanism between ATRNL1 and CEBPB underlying CC progression. Bioinformatics, RT-qPCR and western blotting revealed expression characteristics of ATRNL1 in CC. RT-qPCR measured ATRNL1 and CEBPB levels in CC cell lines. Gain-of-function assays clarified role of ATRNL1 in CC cell behaviors. Bioinformatics, Pearson correlation, ChIP and luciferase reporter experiments assessed association of ATRNL1 and CEBPB in CC cells. Rescue assays assessed regulatory function of CEBPB-ATRNL1 in CC cellular processes. ATRNL1 showed depletion in CC tissue and cells at mRNA and protein levels. ATRNL1 upregulation repressed CC cell viability, migration and EMT. CEBPB bound to ATRNL1 promoter to transcriptionally upregulate ATRNL1 in CC cells. The impact of CEBPB elevation on CC cell viability, migration and EMT were countervailed by ATRNL1 depletion. ATRNL1 and CEBPB present depletion and serve as tumor suppressors in CC cells. ATRNL1 suppresses CC cell malignancy through CEBPB activation, which may provide a potential new direction for seeking therapeutic plans for CC.

Identification of miRNA signatures in serum exosomes as a potential biomarker after radiotherapy treatment in glioma patients.

Despite development in therapies, the high recurrence and low positivity of biomarkers for diagnosis still result in glioma with high mortality. In this study, we aimed to identify a potential miRNA signature to evaluate the effect of radiotherapy in glioma patients. MicroRNA (miRNA) sequencing was performed on miRNAs isolated from serum exosomes in a cohort of glioma patients before and after radiotherapy. A total of 18 up-regulated differentially expressed (DE) miRNAs and 16 down-regulated DE miRNAs were identified. Subsequently, the target genes of DE miRNAs were predicted based on multiple miRNA-target databases. Further, it was indicated that these targets were primarily involved in metabolic process, p53 signaling pathway and cancer pathways, suggesting that these miRNAs play a crucial role in glioma by regulating targets and affect the occurrence and development of the disease. In general, this study presented the variation of miRNAs in blood exosomes before and after radiotherapy. It can not only be helpful for the diagnosis of glioma, but also find new candidate biomarkers for monitoring the condition and evaluating the efficacy of radiotherapy in glioma. It provides a new idea for the diagnosis, treatment and prognosis evaluation of glioma.

Linchpin DNA-binding residues serve as go/no-go controls in the replication factor C-catalyzed clamp-loading mechanism.

DNA polymerases depend on circular sliding clamps for processive replication. Clamps must be loaded onto primer-template DNA (ptDNA) by clamp loaders that open and close clamps around ptDNA in an ATP-fueled reaction. All clamp loaders share a core structure in which five subunits form a spiral chamber that binds the clamp at its base in a twisted open form and encloses ptDNA within, while binding and hydrolyzing ATP to topologically link the clamp and ptDNA. To understand how clamp loaders perform this complex task, here we focused on conserved arginines that might play a central coordinating role in the mechanism because they can alternately contact ptDNA or Walker B glutamate in the ATPase site and lie close to the clamp loader-clamp-binding interface. We mutated Arg-84, Arg-88, and Arg-101 in the ATPase-active B, C, and D subunits of Saccharomyces cerevisiae replication factor C (RFC) clamp loader, respectively, and assessed the impact on multiple transient events in the reaction: proliferating cell nuclear antigen (PCNA) clamp binding/opening/closure/release, ptDNA binding/release, and ATP hydrolysis/product release. The results show that these arginines relay critical information between the PCNA-binding, DNA-binding, and ATPase sites at all steps of the reaction, particularly at a checkpoint before RFC commits to ATP hydrolysis. Moreover, their actions are subunit-specific with RFC-C Arg-88 serving as an accelerator that enables rapid ATP hydrolysis upon contact with ptDNA and RFC-D Arg-101 serving as a brake that confers specificity for ptDNA as the correct substrate for loading PCNA.

TiL4 -Coordinated Black Phosphorus Quantum Dots as an Efficient Contrast Agent for In Vivo Photoacoustic Imaging of Cancer.

Black phosphorus quantum dots coordinated with a sulfonic ester of the titanium ligand are prepared and exhibit enhanced stability. In vitro and in vivo photoacoustic imaging applications demonstrate that the quantum dots can efficiently accumulate inside the tumor producing tumor profiles with high spatial resolution, demonstrating their potential as an efficient agent for photoacoustic imaging.

Circ_0000395 promotes cell growth, metastasis and oxaliplatin resistance by regulating miR-153-5p/MYO6 in colorectal cancer.

BACKGROUND: Circular RNAs (circRNAs) are involved in the regulation of colorectal cancer (CRC) progression and chemoresistence. Here, we attempted to reveal the function and mechanism of circ_0000395 in CRC chemoresistence. METHODS: The expression levels of circ_0000395, microRNA (miR)-153-5p, and myosin VI (MYO6) were determined by quantitative real-time PCR. Cell growth, metastasis and oxaliplatin resistance were evaluated via EdU assay, colony formation assay, flow cytometry, transwell assay, and cell counting kit 8 assay. Xenograft tumor model was adopted to evaluate the role of circ_0000395 on CRC tumor growth and oxaliplatin sensitivity. Protein expression of drug-resistance markers and MYO6 was analyzed by western blot. The target relationship between miR-153-5p and circ_0000395 or MYO6 was validated via dual-luciferase reporter assay and RIP assay. RESULTS: Circ_0000395 expression was enhanced in CRC tissues and cells. Silencing of circ_0000395 repressed CRC cell proliferation, migration and invasion, while promoted apoptosis and oxaliplatin sensitivity. Besides, circ_0000395 knockdown also reduced CRC tumor growth and enhanced the sensitivity of tumor to oxaliplatin. Additionally, circ_0000395 acted as a sponge for miR-153-5p, and miR-153-5p targeted MYO6. Functional experiments suggested that miR-153-5p inhibitor or MYO6 overexpression could reverse the suppressive effect of circ_0000395 knockdown on CRC cell growth, metastasis and oxaliplatin resistance. CONCLUSION: Circ_0000395 promoted CRC cell growth, metastasis and oxaliplatin resistance via the miR-153-5p/MYO6 axis, which might provide new insights into the treatment of CRC.

Impact of individual proliferating cell nuclear antigen-DNA contacts on clamp loading and function on DNA.

Ring-shaped clamp proteins encircle DNA and affect the work of many proteins, notably processive replication by DNA polymerases. Crystal structures of clamps show several cationic residues inside the ring, and in a co-crystal of Escherichia coli ß clamp-DNA, they directly contact the tilted duplex passing through (Georgescu, R. E., Kim, S. S., Yurieva, O., Kuriyan, J., Kong, X. P., and O'Donnell, M. (2008) Structure of a sliding clamp on DNA. Cell 132, 43-54). To investigate the role of these contacts in reactions involving circular clamps, we examined single arginine/lysine mutants of Saccharomyces cerevisiae proliferating cell nuclear antigen (PCNA) in replication factor C (RFC)-catalyzed loading of the clamp onto primer template DNA (ptDNA). Previous kinetic analysis has shown that ptDNA entry inside an ATP-activated RFC-PCNA complex accelerates clamp opening and ATP hydrolysis, which is followed by slow PCNA closure around DNA and product dissociation. Here we directly measured multiple steps in the reaction (PCNA opening, ptDNA binding, PCNA closure, phosphate release, and complex dissociation) to determine whether mutation of PCNA residues Arg-14, Lys-20, Arg-80, Lys-146, Arg-149, or Lys-217 to alanine affects the reaction mechanism. Contrary to earlier steady state analysis of these mutants (McNally, R., Bowman, G. D., Goedken, E. R., O'Donnell, M., and Kuriyan, J. (2010) Analysis of the role of PCNA-DNA contacts during clamp loading. BMC Struct. Biol. 10, 3), our pre-steady state data show that loss of single cationic residues can alter the rates of all DNA-linked steps in the reaction, as well as movement of PCNA on DNA. These results explain an earlier finding that individual arginines and lysines inside human PCNA are essential for polymerase δ processivity (Fukuda, K., Morioka, H., Imajou, S., Ikeda, S., Ohtsuka, E., and Tsurimoto, T. (1995) Structure-function relationship of the eukaryotic DNA replication factor, proliferating cell nuclear antigen. J. Biol. Chem. 270, 22527-22534). Mutations in the N-terminal domain have greater impact than in the C-terminal domain, indicating a positional bias in PCNA-DNA contacts that can influence its functions on DNA.

The variable subdomain of Escherichia coli SecA functions to regulate SecA ATPase activity and ADP release.

Bacterial SecA proteins can be categorized by the presence or absence of a variable subdomain (VAR) located within nucleotide-binding domain II of the SecA DEAD motor. Here we show that VAR is dispensable for SecA function, since the VAR deletion mutant secAΔ519-547 displayed a wild-type rate of cellular growth and protein export. Loss or gain of VAR is extremely rare in the history of bacterial evolution, indicating that it appears to contribute to secA function within the relevant species in their natural environments. VAR removal also results in additional secA phenotypes: azide resistance (Azi(r)) and suppression of signal sequence defects (PrlD). The SecAΔ(519-547) protein was found to be modestly hyperactive for SecA ATPase activities and displayed an accelerated rate of ADP release, consistent with the biochemical basis of azide resistance. Based on our findings, we discuss models whereby VAR allosterically regulates SecA DEAD motor function at SecYEG.

[Influence of DNAzymes against cyclin D1 in tumor cell cycle].

In this study, DNAzymes against cyclin D1 (cyclin D1-DRz) were designed according to the secondary structure of cyclin D1 mRNA which was computed with RNAdraw and Mfold. Cyclin D1-DRz were transfected into tumor cell line u251 and HeLa by oligofectamine. The expression of cyclin D1 was detected by RT-PCR. It was shown that the expression of cyclin D1 gene was suppressed obviously, and the expressions of other cell-cycle related genes such as cyclin E1, cyclin A1 and cyclin B1 were also declined. The cell cycle analysis of tumor cells tansfected with cyclin D1-DRz revealed an arrestment in the G0/G1 phase. In conclusion, the approach is effective and feasible for designing DNAzyme. Cyclin D1-DRz is useful for interfering with the cell cycle procession of tumor cells.

[Pulmonary function of healthy children at ages of 1-48 months in Shenzhen area].

OBJECTIVE: To study the development of pulmonary function of healthy children between 1-48 months. METHODS: A total of 295 healthy children at ages of 1-48 months were classified into 7 groups according to their age, i.e., 1-2 months, 3-4 months, 5-7 months, 8-12 months, 13-24 months, 25-36 months, and 37- 48 months. Pediatric pulmonary function laboratory type 2600 (Sensor Medics Corporation USA) was used to detect tidal flow volume curve, which can partially replace the maximum expiratory flow volume curve and reflect airway ventilation function. Passive expiratory flow volume technique was used to examine respiratory system static compliance and total airway resistance. Open nitrogen washout method was used to measure functional residual capacity. RESULTS: The values of tidal, peak tidal expiratory flow, and respiratory system static compliance functional residual capacity increased with the increasing age and were significantly different among the 7 groups. However, respiratory rate and total airway resistance decreased with the increased age. The value of each parameter of tidal flow volume curve was stable during 1-48 months. CONCLUSIONS: This study displayed the developmental characteristics of pulmonary function of healthy children at ages of 1-48 months, which is useful to observe the changes of pulmonary function in respiratory diseases.

Nanoformulation of D-α-tocopheryl polyethylene glycol 1000 succinate-b-poly(ε-caprolactone-ran-glycolide) diblock copolymer for siRNA targeting HIF-1α for nasopharyngeal carcinoma therapy.

Hypoxia-inducible factor-1α (HIF-1α) is a crucial transcription factor that plays an important role in the carcinogenesis and development of nasopharyngeal carcinoma. In this research, a novel biodegradable D-α-tocopheryl polyethylene glycol 1000 succinate-b-poly(ε-caprolactone-ran-glycolide) (TPGS-b-(PCL-ran-PGA)) nanoparticle (NP) was prepared as a delivery system for small interfering ribonucleic acid (siRNA) molecules targeting HIF-1α in nasopharyngeal carcinoma gene therapy. The results showed that the NPs could efficiently deliver siRNA into CNE-2 cells. CNE-2 cells treated with the HIF-1α siRNA-loaded TPGS-b-(PCL-ran-PGA) NPs showed reduction of HIF-1α expression after 48 hours of incubation via real-time reverse transcriptase-polymerase chain reaction and Western blot analysis. The cytotoxic effect on CNE-2 cells was significantly increased by HIF-1α siRNA-loaded NPs when compared with control groups. In a mouse tumor xenograft model, the HIF-1α siRNA-loaded NPs efficiently suppressed tumor growth, and the levels of HIF-1α mRNA and protein were significantly decreased. These results suggest that TPGS-b-(PCL-ran-PGA) NPs could function as a promising genetic material carrier in antitumor therapy, including therapy for nasopharyngeal carcinoma.

Expression of HIF-1α and CAIX in nasopharyngeal carcinoma and their correlation with patients' prognosis.

This study investigates the expression of hypoxia-inducible factor-l alpha (HIF-1α) and carbonic anhydrase IX (CAIX) in nasopharyngeal carcinoma (NPC) tissues and their correlation with clinicopathological features and prognosis in NPC patients. The expression of HIF-1α and CAIX proteins was detected by immunohistochemical staining in 129 samples of NPC and 20 samples of chronic nasopharyngitis. The correlations between the expression of these two proteins and clinicopathological features and prognosis were evaluated in NPC patients. Our results showed that the positive expression rates of HIF-1α and CAIX proteins in NPC were significantly higher than those in chronic nasopharyngitis (both P < 0.01). In addition, high HIF-1α protein expression was correlated with lymph node metastasis and advanced clinical stage for NPC patients (both P < 0.01), whereas there were no findings of correlations between CAIX protein expression and gender, age, T stage, node involvement and clinical stage (all P > 0.05). The Spearman analysis indicated that HIF-1α was positively correlated with CAIX expression (r = 0.249, P = 0.004). HIF-1α and CAIX co-expression was associated with the poor overall survival (OS), progression-free survival (PFS), loco-regional relapse-free survival (LRRFS) and distant metastasis-free survival (DMFS) in NPC patients (P = 0.017, P = 0.022, P = 0.033, and P = 0.017, respectively). Multivariate analysis showed that the positive expression of CAIX protein was an independent prognostic factor for PFS, LRRFS and DMFS. In conclusion, overexpression of HIF-1α and CAIX might be involved in the carcinogenesis and development of NPC and they were associated with patients' poor prognosis.

ATP binding and hydrolysis-driven rate-determining events in the RFC-catalyzed PCNA clamp loading reaction.

The multi-subunit replication factor C (RFC) complex loads circular proliferating cell nuclear antigen (PCNA) clamps onto DNA where they serve as mobile tethers for polymerases and coordinate the functions of many other DNA metabolic proteins. The clamp loading reaction is complex, involving multiple components (RFC, PCNA, DNA, and ATP) and events (minimally: PCNA opening/closing, DNA binding/release, and ATP binding/hydrolysis) that yield a topologically linked clamp·DNA product in less than a second. Here, we report pre-steady-state measurements of several steps in the reaction catalyzed by Saccharomyces cerevisiae RFC and present a comprehensive kinetic model based on global analysis of the data. Highlights of the reaction mechanism are that ATP binding to RFC initiates slow activation of the clamp loader, enabling it to open PCNA (at ~2 s(-1)) and bind primer-template DNA (ptDNA). Rapid binding of ptDNA leads to formation of the RFC·ATP·PCNA(open)·ptDNA complex, which catalyzes a burst of ATP hydrolysis. Another slow step in the reaction follows ATP hydrolysis and is associated with PCNA closure around ptDNA (8 s(-1)). Dissociation of PCNA·ptDNA from RFC leads to catalytic turnover. We propose that these early and late rate-determining events are intramolecular conformational changes in RFC and PCNA that control clamp opening and closure, and that ATP binding and hydrolysis switch RFC between conformations with high and low affinities, respectively, for open PCNA and ptDNA, and thus bookend the clamp loading reaction.

Mechanism of ATP-driven PCNA clamp loading by S. cerevisiae RFC.

Circular clamps tether polymerases to DNA, serving as essential processivity factors in genome replication, and function in other critical cellular processes as well. Clamp loaders catalyze clamp assembly onto DNA, and the question of how these proteins construct a topological link between a clamp and DNA, especially the mechanism by which ATP is utilized for the task, remains open. Here we describe pre-steady-state analysis of ATP hydrolysis, proliferating cell nuclear antigen (PCNA) clamp opening, and DNA binding by Saccharomyces cerevisiae replication factor C (RFC), and present the first kinetic model of a eukaryotic clamp-loading reaction validated by global data analysis. ATP binding to multiple RFC subunits initiates a slow conformational change in the clamp loader, enabling it to bind and open PCNA and to bind DNA as well. PCNA opening locks RFC into an active state, and the resulting RFC.ATP.PCNA((open)) intermediate is ready for the entry of DNA into the clamp. DNA binding commits RFC to ATP hydrolysis, which is followed by PCNA closure and PCNA.DNA release. This model enables quantitative understanding of the multistep mechanism of a eukaryotic clamp loader and furthermore facilitates comparative analysis of loaders from diverse organisms.