Bing-Li Wu

MiR‐142‐3p as a potential prognostic biomarker for esophageal squamous cell carcinoma

microRNAs (miRNAs), small non‐coding RNAs, are always aberrantly expressed in many diseases including human cancers. The aim of this study was to examine and determine the clinical significance of hsa‐miR‐31, hsa‐miR‐142‐3p, hsa‐miR‐338‐3p, and hsa‐miR‐1261 expression in esophageal squamous cell carcinoma (ESCC).

MiRNA profile in esophageal squamous cell carcinoma: Downregulation of miR-143 and miR-145

AIM To investigate the expression profile of miRNA in esophageal squamous cell carcinoma (ESCC). METHODS The expression profile of miRNA in ESCC tissues was analyzed by miRNA microarray. The expression levels of miR-143 and miR-145 in 86 ESCC patients were determined by real-time polymerase chain reaction (PCR) using TaqMan assay. The mobility effect was estimated by wound-healing using esophageal carcinoma cells transfected with miRNA expression plasmids. RESULTS A set of miRNAs was found to be deregulated in the ESCC tissues, and the expression levels of miR-143 and -145 were significantly decreased in most of the ESCC tissues examined. Both miR-143 and miR-145 expression correlated with tumor invasion depth. The transfection of human esophageal carcinoma cells with miR-143 and miR-145 expression plasmids resulted in a greater inhibition of cell mobility, however, the protein level of the previously reported target of miR-145, FSCN1, did not show any significant downregulation. CONCLUSION These findings suggest that the deregulation of miRNAs plays an important role in the progression of ESCC. Both miR-143 and miR-145 might act as anti-oncomirs common to ESCC.

miR-200b suppresses invasiveness and modulates the cytoskeletal and adhesive machinery in esophageal squamous cell carcinoma cells via targeting Kindlin-2.

To further our understanding of the pathobiology of esophageal squamous cell carcinoma (ESCC), we previously performed microRNA profiling that revealed downregulation of miR-200b in ESCC. Using quantitative real-time PCR applied to 88 patient samples, we confirmed that ESCC tumors expressed significantly lower levels of miR-200b compared with the respective adjacent benign tissues (P = 0.003). Importantly, downregulation of miR-200b significantly correlated with shortened survival (P = 0.025), lymph node metastasis (P = 0.002) and advanced clinical stage (P = 0.020) in ESCC patients. Quantitative mass spectrometry identified 57 putative miR-200b targets, including Kindlin-2, previously implicated in the regulation of tumor invasiveness and actin cytoskeleton in other cell types. Enforced expression of miR-200b mimic in ESCC cells led to a decrease of Kindlin-2 expression, whereas transfection of miR-200b inhibitor induced Kindlin-2 expression. Furthermore, transfection of miR-200b mimic or knockdown of Kindlin-2 in ESCC cells decreased cell protrusion and focal adhesion (FA) formation, reduced cell spreading and invasiveness/migration. Enforced expression of Kindlin-2 largely abrogated the inhibitory effects of miR-200b on ESCC cell invasiveness. Mechanistic studies revealed that Rho-family guanosine triphosphatases and FA kinase mediated the biological effects of the miR-200b-Kindlin-2 axis in ESCC cells. To conclude, loss of miR-200b, a frequent biochemical defect in ESCC, correlates with aggressive clinical features. The tumor suppressor effects of miR-200b may be due to its suppression of Kindlin-2, a novel target of miR-200b that modulates actin cytoskeleton, FA formation and the migratory/invasiveness properties of ESCC.

Down-regulated desmocollin-2 promotes cell aggressiveness through redistributing adherens junctions and activating beta-catenin signalling in oesophageal squamous cell carcinoma.

In contrast to the well‐recognized loss of adherens junctions in cancer progression, the role of desmosomal components in cancer development has not been well explored. We previously demonstrated that desmocollin‐2 (DSC2), a desmosomal cadherin protein, is reduced in oesophageal squamous cell carcinoma (ESCC), and is associated with enhanced tumour metastasis and poor prognosis. Here, we report that restoration of DSC2 in ESCC cells impeded cell migration and invasion both in vitro and in vivo, whereas siRNA‐mediated suppression of DSC2 expression increased cell motility. In E‐cadherin‐expressing ESCC cells, DSC2 restoration strengthened E‐cadherin‐mediated adherens junctions and promoted the localization of β‐catenin at these junctions, which indirectly inhibited β‐catenin‐dependent transcription. These effects of DSC2 were not present in EC109 cells that lacked E‐cadherin expression. ESCC patients with tumours that had reduced E‐cadherin and negative DSC2 had poorer clinical outcomes than patients with tumours that lacked either E‐cadherin or DSC2, implying that the invasive potential of ESCC cells was restricted by both DSC2 and E‐cadherin‐dependent junctions. Further studies revealed that DSC2 was a downstream target of miR‐25. Enhanced miR‐25 promoted ESCC cell invasiveness, whereas restoration of DSC2 abolished these effects. Collectively, our work suggests that miR‐25‐mediated down‐regulation of DSC2 promotes ESCC cell aggressiveness through redistributing adherens junctions and activating beta‐catenin signalling. Copyright

Neutrophil gelatinase-associated lipocalin and its receptor: independent prognostic factors of oesophageal squamous cell carcinoma

Aim Previous studies have shown that neutrophil gelatinase-associated lipocalin (NGAL) is overexpressed in oesophageal squamous cell carcinoma (ESCC) and closely associated with the invasiveness of ESCC cells. Recently, NGAL receptor (NGALR) was identified from ESCC cells, and was also found to be increased in ESCC. The purpose of this study was to reveal the clinical significance of NGAL and/or NGALR in ESCC. Methods Tissue microarray was performed to detect expression of NGAL and NGALR in 222 ESCC specimens. Pearson χ2 test was used to analyse correlations between NGAL and/or NGALR expression and clinicopathological features. Kaplan–Meier survival curves and the Cox proportional hazards regression model were used to evaluate the effect of NGAL and/or NGALR expression on prognosis of patients with ESCC. Results NGAL and NGALR were highly expressed in ESCC. χ2 test results showed no significant correlations between NGAL or NGALR expression and clinicopathological features. However, NGAL/NGALR coexpression correlated with histological differentiation grade (p=0.033). Survival analysis showed that positive expression of NGAL or NGALR was significantly associated with a poor prognosis for patients with ESCC (p=0.000 or p=0.002). Patients with positive expression of both NGAL and NGALR had a shorter survival time than those with negative expression of both (p=0.048). Multivariate analysis showed that both NGAL and NGALR were independent prognostic factors. Conclusion These results indicate that both NGAL and NGALR may be involved in the progression of ESCC and can be considered as independent prognostic factors of ESCC.

Dissection of miRNA-miRNA Interaction in Esophageal Squamous Cell Carcinoma

The relationships between miRNAs and their regulatory influences in esophageal carcinoma remain largely unknown. Accumulated evidence suggests that delineation of subpathways within an entire pathway can underlie complex diseases. To analyze the regulation of differentially expressed miRNAs in subpathways of esophageal squamous cell carcinoma (ESCC), we constructed bipartite miRNA and subpathway networks to determine miRNA regulatory influences on subpathways. The miRNA-subpathway network indicated that miRNAs regulate numerous subpathways. Two principal biological networks were derived from the miRNA-subpathway network by the hypergeometric test. This miRNA-miRNA network revealed the co-regulation of subpathways between the upregulated and downregulated miRNAs. Subpathway-subpathway networks characterized scale free, small world, and modular architecture. K-clique analysis revealed co-regulation of subpathways between certain downregulated and upregulated miRNAs. When ESCC patients were grouped according to their expression levels of paired upregulation of miR-31 and downregulation of miR-338-3p, survival time analysis revealed a significant difference based on miR-31-miR-338-3p interaction. These findings can facilitate the understanding of the biological meaning of miRNA-miRNA interactions with either the same or opposite expression trend.

Network based analyses of gene expression profile of LCN2 overexpression in esophageal squamous cell carcinoma

LCN2 (lipocalin 2) is a member of the lipocalin family of proteins that transport small, hydrophobic ligands. LCN2 is elevated in various cancers including esophageal squamous cell carcinoma (ESCC). In this study, LCN2 was overexpressed in the EC109 ESCC cell line and we applied integrated analyses of the gene expression data to identify protein-protein interactions (PPI) network to enhance our understanding of the role of LCN2 in ESCC. Through further mining of PPI sub-networks, hundreds of differentially expressed genes (DEGs) were identified to interact with thousands of other proteins. Subcellular localization analyses found the DEGs and their directly or indirectly interacting proteins distributed in multiple layers, which was applied to analyze the possible paths between two DEGs. Gene Ontology annotation generated a functional annotation map and found hundreds of significant terms, especially those associated with the known and potential roles of LCN2 protein. The algorithm of Random Walk with Restart was applied to prioritize the DEGs and identified several cancer-related DEGs ranked closest to LCN2 protein. These analyses based on PPI network have greatly expanded our understanding of the mRNA expression profile of LCN2 overexpresssion for future examination of the roles and mechanisms of LCN2.

Determinants of career aspirations of medical students in southern China

BackgroundWith recent changes in both the Chinese medical system and compensation of medical doctors, the career aspirations of Chinese medical students have become more diverse. Shantou University Medical College has conducted evaluations and instituted programs to enhance student preparedness to enter a variety of medical careers.MethodsA survey was conducted with 85 students to evaluate medical career aspirations and their association with family background, personal skills, English language proficiency, and interest in biomedical research, which were considered as possible factors affecting their career interest.ResultsChinese students aspire to traditional as well as nontraditional medical careers. A significant minority of students are now interested in nontraditional careers such as medical teaching or research. However, poor proficiency in the English language and lack of computer skills may limit their academic and career opportunities.ConclusionCareer aspirations have changed among medical undergraduates. Although many wish to pursue a traditional clinical doctor career, many are interested in research and teaching careers. Factors such as family background, personal characteristics, school mentoring, and extracurricular support may play a role.

A systematic analysis of human lipocalin family and its expression in esophageal carcinoma.

The lipocalin proteins (lipocalins) are a large family of small proteins characterized by low sequence similarity and highly conserved crystal structures. Lipocalins have been found to play important roles in many human diseases. For this reason, a systemic analysis of the molecular properties of human lipocalins is essential. In this study, human lipocalins were found to contain four structurally conserved regions (SCRs) and could be divided into two subgroups. A human lipocalin protein-protein interaction network (PPIN) was constructed and integrated with their expression data in esophageal carcinoma. Many lipocalins showed obvious co-expression patterns in esophageal carcinoma. Their subcellular distributions also suggested these lipocalins may transfer signals from the extracellular space to the nucleus using the pathway-like paths. These analyses also expanded our knowledge about this human ancient protein family in the background of esophageal carcinoma.

Identification of a novel lysyl oxidase-like 2 alternative splicing isoform, LOXL2 Δe13, in esophageal squamous cell carcinoma

Lysyl oxidase-like 2 (LOXL2) participates in every stage of cancer progression and promotes invasion and metastasis. In this study, we identified a novel alternative splicing isoform of LOXL2, namely LOXL2 Δe13, which lacked exon 13. Deletion of exon 13 caused an open reading frame shift and produced a truncated protein. LOXL2 Δe13 was expressed ubiquitously in cell lines and tissues and was mainly localized to the cytoplasm. Although it showed impaired deamination enzymatic activity compared with full-length LOXL2, LOXL2 Δe13 promoted the cell mobility and invasion of esophageal squamous cell carcinoma (ESCC) cells to greater degrees. In further research on the mechanisms, gene expression profiling and signaling pathway analysis revealed that LOXL2 Δe13 induced the expression of MAPK8 without affecting the FAK, AKT, and ERK signaling pathways. RNAi-mediated knockdown of MAPK8 could block the cell migration promoted by LOXL2De13, but it had little effect on that of full-length LOXL2. Our data suggest that LOXL2 Δe13 modulates the effects of cancer cell migration and invasion through a different mechanism from that of full-length LOXL2 and that it may play a very important role in tumor carcinogenesis and progression.