Shuping Peng

Circulating miR-17, miR-20a, miR-29c, and miR-223 Combined as Non-Invasive Biomarkers in Nasopharyngeal Carcinoma

Background MicroRNAs have been considered as a kind of potential novel biomarker for cancer detection due to their remarkable stability in the blood and the characteristics of their expression profile in many diseases. Methods We performed microarray-based serum miRNA profiling on the serum of twenty nasopharyngeal carcinoma patients at diagnosis along with 20 non-cancerous individuals as controls. This was followed by a real-time quantitative Polymerase Chain Reaction (RT-qPCR) in a separate cohort of thirty patients with nasopharyngeal carcinoma and thirty age- matched non-cancerous volunteers. A model for diagnosis was established by a conversion of mathematical calculation formula which has been validated by analyzing 74 cases of patients with nasopharyngeal carcinoma and 57 cases of non-cancerous volunteers. Results The profiles showed that 39 and 17 miRNAs are exclusively expressed in the serum of non-cancerous volunteers and of patients with nasopharyngeal carcinoma respectively. 4 miRNAs including miR-17, miR-20a, miR-29c, and miR-223 were found to be expressed differentially in the serum of NPC compared with that of non-cancerous control. Based on this, a diagnosis equation with Ct difference method has been established to distinguish NPC cases and non-cancerous controls and validated with high sensitivity and specificity. Conclusions We demonstrate that the serum miRNA-based biomarker model become a novel tool for NPC detection. The circulating 4-miRNA-based method may provide a novel strategy for NPC diagnosis.

Current Progress in Bioactive Ceramic Scaffolds for Bone Repair and Regeneration

Bioactive ceramics have received great attention in the past decades owing to their success in stimulating cell proliferation, differentiation and bone tissue regeneration. They can react and form chemical bonds with cells and tissues in human body. This paper provides a comprehensive review of the application of bioactive ceramics for bone repair and regeneration. The review systematically summarizes the types and characters of bioactive ceramics, the fabrication methods for nanostructure and hierarchically porous structure, typical toughness methods for ceramic scaffold and corresponding mechanisms such as fiber toughness, whisker toughness and particle toughness. Moreover, greater insights into the mechanisms of interaction between ceramics and cells are provided, as well as the development of ceramic-based composite materials. The development and challenges of bioactive ceramics are also discussed from the perspective of bone repair and regeneration.

Enhancement mechanisms of graphene in nano-58S bioactive glass scaffold: mechanical and biological performance

Graphene is a novel material and currently popular as an enabler for the next-generation nanocomposites. Here, we report the use of graphene to improve the mechanical properties of nano-58S bioactive glass for bone repair and regeneration. And the composite scaffolds were fabricated by a homemade selective laser sintering system. Qualitative and quantitative analysis demonstrated the successful incorporation of graphene into the scaffold without obvious structural damage and weight loss. The optimum compressive strength and fracture toughness reached 48.65 ± 3.19 MPa and 1.94 ± 0.10 MPa·m1/2 with graphene content of 0.5 wt%, indicating significant improvements by 105% and 38% respectively. The mechanisms of pull-out, crack bridging, crack deflection and crack tip shielding were found to be responsible for the mechanical enhancement. Simulated body fluid and cell culture tests indicated favorable bioactivity and biocompatibility of the composite scaffold. The results suggest a great potential of graphene/nano-58S composite scaffold for bone tissue engineering applications.

AFAP1-AS1, a long noncoding RNA upregulated in lung cancer and promotes invasion and metastasis

Long noncoding RNAs (lncRNAs) have emerged as a major regulator of cancer. Significant fraction of lncRNAs is represented on widely used microarray platforms; however, many of which have no known function. To discover novel lung cancer-related lncRNAs, we analyzed the lncRNA expression patterns in five sets of previously published lung cancer gene expression profile data that were represented on Affymetrix HG-U133 Plus 2.0 array, and identified dysregulated lncRNAs in lung cancer. One lncRNA, actin filament associated protein 1 antisense RNA1 (AFAP1-AS1), was the most significantly upregulated in lung cancer and associated with poor prognosis. In vitro experiments demonstrated that AFAP1-AS1 knockdown significantly inhibited the cell invasive and migration capability in lung cancer cells. AFAP1-AS1 knockdown also increased the expression of its antisense protein coding gene, actin filament associated protein 1 (AFAP1), and affected the expression levels of several small GTPase family members and molecules in the actin cytokeratin signaling pathway, which suggested that AFAP1-AS1 promoted cancer cell metastasis via regulation of actin filament integrity. Our findings extend the number of noncoding RNAs functionally implicated in lung cancer progression and highlight the role of AFAP1-AS1 as potential prognostic biomarker and therapeutic target of lung cancer.

A novel two-step sintering for nano-hydroxyapatite scaffolds for bone tissue engineering

In this study, nano-hydroxyapatite scaffolds with high mechanical strength and an interconnected porous structure were prepared using NTSS for the first time. The first step was performed using a laser characterized by the rapid heating to skip the surface diffusion and to obtain the driving force for grain boundary diffusion. Additionally, the interconnected porous structure was achieved by SLS. The second step consisted of isothermal heating in a furnace at a lower temperature (T2) than that of the laser beam to further increase the density and to suppress grain growth by exploiting the difference in kinetics between grain-boundary diffusion and grain-boundary migration. The results indicated that the mechanical properties first increased and then decreased as T2 was increased from 1050 to 1250°C. The optimal fracture toughness, compressive strength and stiffness were 1.69 MPam1/2, 18.68 MPa and 245.79 MPa, respectively. At the optimal point, the T2 was 1100°C, the grain size was 60 nm and the relative density was 97.6%. The decrease in mechanical properties was due to the growth of grains and the decomposition of HAP. The cytocompatibility test results indicated that cells adhered and spread well on the scaffolds. A bone-like apatite layer formed, indicating good bioactivity.

Graphene oxide reinforced poly(vinyl alcohol): nanocomposite scaffolds for tissue engineering applications

In this study, graphene oxide (GO) is incorporated into poly(vinyl alcohol) (PVA) for the purpose of improving the mechanical properties. Nanocomposite scaffolds with an interconnected porous structure are fabricated by selective laser sintering (SLS). The results indicate that the highest improvements in the mechanical properties are obtained, that is, a 60%, 152% and 69% improvement of compressive strength, Youngs modulus and tensile strength is achieved at the GO loading of 2.5 wt%, respectively. The reason can be attributed to the enhanced load transfer due to the homogeneous dispersion of GO sheets and the strong hydrogen bonding interactions between GO and the PVA matrix. The agglomerates and restacking of GO sheets occur on further increasing the GO loading, which leads to the decrease in the mechanical properties. In addition, osteoblast-like cells attach and grow well on the surface of scaffolds, and proliferate with increasing time of culture. The GO/PVA nanocomposite scaffolds are potential candidates for bone tissue engineering.

Identification of nuclear localization signal that governs nuclear import of BRD7 and its essential roles in inhibiting cell cycle progression

BRD7, a novel bromodomain gene, is identified to be associated with nasopharyngeal carcinoma (NPC). Decreased or loss of expression of BRD7 was detected in NPC biopsies and cell lines. Overexpression of BRD7 could inhibit NPC cell growth and arrest cells in cell cycle by transcriptionally regulating some important molecules involved in ras/MEK/ERK and Rb/E2F pathway, and downregulate the promoter activity of E2F3. In the present study, the subcellular localization of BRD7 was investigated. It was found that BRD7 was mainly localized in nucleus without distinct cell‐specific difference between COS7 and HNE1. Furthermore, a functional nuclear localization signal (NLS) sequence ranging from amino acid 65 to 96 was identified and characterized. The NLS is composed of a cluster of four bipartite nuclear targeting sequences, which are tightly linked and extremely overlapped. We found that whether the entire NLS or the four bipartite nuclear targeting sequences could respectively determine the nuclear import of green fluorescent protein (GFP). The most important is that NLS‐deleted BRD7 shifted the nuclear localization to be mostly in cytoplasm, and failed or reduced to negatively regulate the expression of cell cycle related molecules, cyclin D1 and E2F3, and cell cycle progression from G1 to S phase. In conclusion, NLS is an essential motif affecting BRD7 nuclear distribution, and the nuclear localization of BRD7 is critical for the expression of cell cycle related molecules and cell biological function. J. Cell. Biochem. 98: 920–930, 2006.

NGX6 gene inhibits cell proliferation and plays a negative role in EGFR pathway in nasopharyngeal carcinoma cells.

Nasopharyngeal carcinoma (NPC) is a common cancer in South China but is rare in other parts of the world. A novel NPC‐related gene was isolated by location candidate cloning strategy, whose expression was down‐regulated in NPC. This gene was designated human NGX6 (Genbank accession AF188239) and encoded a predicted protein of 338 amino acids that harbors an EGF‐like domain. The effects of NGX6 on cells from human NPC cell line HNE1 were investigated. The cells transfected with NGX6 had a markedly high expression of NGX6, leading to significant decrease in cell proliferation and the capability to form colonies in soft agar, delaying the G0–G1 cell cycle progression. Flow cytometry assay indicated that the expression of cyclin D1 significantly decreased in NGX6‐transfected HNE1 cells as well as cyclin A and E. There was a delay in tumor formation and a dramatic reduction in tumor size when cells transfected with NGX6 were injected into nude mice. In another way, we found NGX6 played a negative role in EGFR Ras/Mek/MAPK pathway. We propose that NGX6, as an EGF‐like domain gene, could delay cell cycle G0–G1 progression and thus inhibit cell proliferation by negatively regulating EGFR pathway in NPC cells and down‐regulating the expression of cyclin D1 and E.

LOC401317, a p53-regulated long non-coding RNA, inhibits cell proliferation and induces apoptosis in the nasopharyngeal carcinoma cell line HNE2

Recent studies have revealed that long non-coding RNAs participate in all steps of cancer initiation and progression by regulating protein-coding genes at the epigenetic, transcriptional, and post-transcriptional levels. Long non-coding RNAs are in turn regulated by other genes, forming a complex regulatory network. The regulation networks between the p53 tumor suppressor and these RNAs in nasopharyngeal carcinoma remains unclear. The aims of this study were to investigate the regulatory roles of the TP53 gene in regulating long non-coding RNA expression profiles and to study the function of a TP53-regulated long non-coding RNA (LOC401317) in the nasopharyngeal carcinoma cell line HNE2. Long non-coding RNA expression profiling indicated that 133 long non-coding RNAs were upregulated in the human NPC cell line HNE2 cells following TP53 overexpression, while 1057 were downregulated. Among these aberrantly expressed long non-coding RNAs, LOC401317 was the most significantly upregulated one. Further studies indicated that LOC401317 is directly regulated by p53 and that ectopic expression of LOC401317 inhibits HNE2 cell proliferation in vitro and in vivo by inducing cell cycle arrest and apoptosis. LOC401317 inhibited cell cycle progression by increasing p21 expression and decreasing cyclin D1 and cyclin E1 expression and promoted apoptosis through the induction of poly(ADP-ribose) polymerase and caspase-3 cleavage. Collectively, these results suggest that LOC401317 is directly regulated by p53 and exerts antitumor effects in HNE2 nasopharyngeal carcinoma cells.

Transcriptional regulation of BRD7 expression by Sp1 and c-Myc

BackgroundBromodomain is an evolutionally conserved domain that is found in proteins strongly implicated in signal-dependent transcriptional regulation. Genetic alterations of bromodomain genes contributed to the development of many human cancers and other disorders. BRD7 is a recently identified bromodomain gene. It plays a critical role in cellular growth, cell cycle progression, and signal-dependent gene expression. Previous studies showed that BRD7 gene exhibited much higher-level of mRNA expression in normal nasopharyngeal epithelia than in nasopharyngeal carcinoma (NPC) biopsies and cell lines. However, little is known about its transcriptional regulation. In this study, we explored the transcriptional regulation of BRD7 gene.MethodPotential binding sites of transcription factors within the promoter region of BRD7 gene were predicted with MatInspector Professional http://genomatix.de/cgi-bin/matinspector_prof/mat_fam.pl. Mutation construct methods and luciferase assays were performed to define the minimal promoter of BRD7 gene. RT-PCR and western blot assays were used to detect the endogenous expression of transcription factor Sp1, c-Myc and E2F6 in all cell lines used in this study. Electrophoretic mobility shift assays (EMSA) and Chromatin immunoprecipitation (ChIP) were used to detect the direct transcription factors that are responsible for the promoter activity of BRD7 gene. DNA vector-based siRNA technology and cell transfection methods were employed to establish clone pools that stably expresses SiRNA against c-Myc expression in nasopharyngeal carcinoma 5-8F cells. Real-time PCR was used to detect mRNA expression of BRD7 gene in 5-8F/Si-c-Myc cells.ResultsWe defined the minimal promoter of BRD7 gene in a 55-bp region (from -266 to -212bp), and identified that its promoter activity is inversely related to c-Myc expression. Sp1 binds to the Sp1/Myc-Max overlapping site of BRD7 minimal promoter, and slightly positively regulate its promoter activity. c-Myc binds to this Sp1/Myc-Max overlapping site as well, and negatively regulates the promoter activity and endogenous mRNA expression of BRD7 gene. Knock-down of c-Myc increases the promoter activity and mRNA level of BRD7 gene. The luciferase activity of the mutated promoter constructs showed that Sp1/Myc-Max overlapping site is a positive regulation element of BRD7 promoter.ConclusionThese studies provide for the first time the evidence that c-Myc is indeed a negative regulator of BRD7 gene. These findings will help to further understand and uncover the bio-functions of BRD7 gene involved in the pathogenesis of NPC.