Gaochao Dong

Circular RNA has_circ_0067934 is upregulated in esophageal squamous cell carcinoma and promoted proliferation

Esophageal squamous cell carcinoma (ESCC) is one of the most prevalent and deadly types of cancer worldwide especially in Eastern Asia and the prognosis of ESCC remain poor. Recent evidence suggests that circular RNAs (circRNAs) play important roles in multiple diseases, including cancer. In this study, we characterized a novel circRNA termed hsa_circ_0067934 in ESCC tumor tissues and cell lines. We analyzed a cohort of 51 patients and found that hsa_circ_0067934 was significantly overexpressed in ESCC tissues compared with paired adjacent normal tissues. The high expression level of hsa_circ_0067934 was associated with poor differentiation (P = 0.025), I-II T stage (P = 0.04), and I-II TNM stage (P = 0.021). The in vitro silence of hsa_circ_0067934 by siRNA inhibited the proliferation and migration of ESCC cells and blocked cell cycle progression. Cell fraction analyses and fluorescence in situ hybridization detected that hsa_circ_0067934 was mostly located in the cytoplasm. Our findings suggest that hsa_circ_0067934 is upregulated in ESCC tumor tissue. Our data suggest that hsa_circ_0067934 represents a novel potential biomarker and therapeutic target of ESCC.

PKM2 and cancer: The function of PKM2 beyond glycolysis (Review)

Metabolic reprogramming is a hallmark of cancer cells and is used by cancer cells for growth and survival. Pyruvate kinase muscle isozyme M2 (PKM2) is a limiting glycolytic enzyme that catalyzes the final step in glycolysis, which is key in tumor metabolism and growth. The present review discusses the expression and regulation of PKM2, and reports the dominant role that PKM2 plays in glycolysis to achieve the nutrient demands of cancer cell proliferation. In addition, the present study discusses the non-metabolic function of PKM2, and its role as a coactivator and protein kinase, which contributes to tumorigenesis. Furthermore, conflicting studies concerning the role of PKM2 as a therapeutic target are reviewed. The improved understanding of PKM2 may provide a noval approach for cancer treatment.

DNA methylation mediated silencing of microRNA-145 is a potential prognostic marker in patients with lung adenocarcinoma.

The molecular mechanism of down-regulated microRNA-145 (miR-145) expression in lung adenocarcinoma (LAC) remains largely unknown. We hypothesized that aberrant hyper-methylation of the CpG sites silenced the expression of miR-145 in LAC. In consideration of its pivotal role in LAC development and progression, we also evaluated the clinical utility of miR-145 as a prognostic marker. We assessed the DNA methylation status of the miR-145 promoter region in 20 pairs of LAC and the matched non-tumor specimens. We subsequently applied our own LAC tissue microarray containing 92 pairs of tumor and non-tumor tissues with long time follow-up records to evaluate whether miR-145 is a potential prognostic marker in LAC. The Sequenom EpiTYPER MassArray analysis showed that miR-145 was down-regulated in human LAC tissues accompanied by increased DNA methylation of its upstream region, which was further validated by the data from TCGA database. Significance was observed between miR-145 expression and clinic-pathologic parameters. Univariate and multivariate analysis revealed that miR-145 expression level was an independent risk factor for both OS and DFS in LAC patients. Taken together, DNA hyper-methylation in the miR-145 promoter region reduced its expression in LAC and miR-145 expression level might serve as a novel prognostic biomarker.

Glypican-5 suppresses Epithelial-Mesenchymal Transition of the lung adenocarcinoma by competitively binding to Wnt3a

We previously demonstrated that Glypican-5 (GPC5), one of the members of heparan sulfate proteoglycan, was a novel tumor metastasis suppressor in lung adenocarcinoma (LAC). However, it remains unclear how GPC5 suppresses lung cancer metastasis. Here, we found over-expression GPC5 induced significant Epithelial-Mesenchymal Transition (EMT) process of A549 cells in vitro. Bioinformatic analysis of RNA sequencing data indicated that GPC5 was co-expressed with EMT related markers, E-cadherin and Vimentin. Wnt/β-catenin signaling pathway was also significantly enriched after overexpressing GPC5. Further in vitro experiments demonstrated that overexpressing GPC5 could block the translocation of β-catenin from cytoplasm to nucleus and therefore inactivate the Wnt/β-catenin signaling pathway by competitively binding to Wnt3a. Subsequent rescue experiments demonstrated that GPC5-induced metastatic phenotype and EMT process suppression were significantly reversed when cells cultured in Wnt3a conditioned media. By establishing the metastatic model in severe combined immune deficiency (SCID) mice, we also demonstrated that overexpressing GPC5 suppressed LAC migration and accordingly alerted EMT related markers, which including up-regulated E-cadherin and down-regulated Vimentin in both lung and liver metastasis. Finally, clinical samples of LAC further validated that GPC5 expression was positively correlated with E-cadherin, and negatively correlated with both Twist1 and MMP2. Taken together, these data suggested that GPC5 is able to suppress the LAC metastasis by competitively binding to Wnt3a and inactivating the Wnt/β-catenin signaling pathway. Our findings expanded the role and the molecular mechanism of GPC5 on malignant bionomics of LAC.

Comprehensive analysis of lncRNA expression profiles and identification of functional lncRNAs in lung adenocarcinoma.

Increasing evidence has highlighted the critical roles of long non-coding RNAs (lncRNAs) as biomarkers and therapeutic targets for cancer. Here, we characterized lncRNA expression profile in lung adenocarcinoma (LUAD). A training-validation method was applied to identify differentially expressed lncRNAs between LUAD samples and normal samples. 856 differentially expressed lncRNAs were identified. Bioinformatics analyses showed that these lncRNAs were located nearby transcription start sites and key regulators of cancer and these lncRNAs were involved in many critical biological processes. We found the lung cancer associated lncRNA 6 (LCAL6) was significantly unregulated and predicted survival in LUAD. Silence of LCAL6 inhibited LUAD tumor cell growth both in vitro and in vivo. To summary, we comprehensively analyze lncRNA expression profile in LUAD and provide resources for further search for clinical biomarkers and therapeutic targets of LUAD.

Differentially expressed protein-coding genes and long noncoding RNA in early-stage lung cancer

Due to the application of low-dose computed tomography screening, more and more early-stage lung cancers have been diagnosed. Thus, it is essential to characterize the gene expression profile of early-stage lung cancer to develop potential biomarkers for early diagnosis and therapeutic targets. Here, we analyzed microarray data of 181 early-stage lung cancer patients. By comparing gene expression between different tumor and lymph node metastasis stages, we identified various differentially expressed protein-coding genes and long noncoding RNA (lncRNA) in the comparisons of T2 vs. T2 and N1- vs. N0-stage lung cancer. Functional analyses revealed that these differentially expressed genes were enriched in various tumorigenesis or metastasis-related pathways. Survival analysis indicated that two protein-coding genes, C7 and SCN7A, were significantly associated survival of lung cancer. Notably, a novel lncRNA, LINC00313, was highly expressed in both T2- and N1-stage lung cancers. On the other hand, LINC00313 was also upregulated in lung cancer and metastasized lung cancer tissues, compared with adjacent lung tissues and primary lung cancer tissues. Additionally, higher expression level of LINC00313 indicated poor prognosis of lung cancer (hazard ratio = 0.658). Overall, we characterized the expression profiles of protein-coding genes and lncRNA in early-stage lung cancer and found that LINC00313 could be a biomarker for lung cancer.

The Circular RNA circPRKCI Promotes Tumor Growth in Lung Adenocarcinoma

Somatic copy number variations (CNV) may drive cancer progression through both coding and noncoding transcripts. However, noncoding transcripts resulting from CNV are largely unknown, especially for circular RNAs. By integrating bioinformatics analyses of alerted circRNAs and focal CNV in lung adenocarcinoma, we identify a proto-oncogenic circular RNA (circPRKCI) from the 3q26.2 amplicon, one of the most frequent genomic aberrations in multiple cancers. circPRKCI was overexpressed in lung adenocarcinoma tissues, in part due to amplification of the 3q26.2 locus, and promoted proliferation and tumorigenesis of lung adenocarcinoma. circPRKCI functioned as a sponge for both miR-545 and miR-589 and abrogated their suppression of the protumorigenic transcription factor E2F7 Intratumor injection of cholesterol-conjugated siRNA specifically targeting circPRKCI inhibited tumor growth in a patient-derived lung adenocarcinoma xenograft model. In summary, circPRKCI is crucial for tumorigenesis and may serve as a potential therapeutic target in patients with lung adenocarcinoma.Significance: These findings reveal high expression of the circular RNA circPRKCI drives lung adenocarcinoma tumorigenesis. Cancer Res; 78(11); 2839-51. ©2018 AACR.

A nomogram to predict the survival of stage IIIA-N2 non–small cell lung cancer after surgery

Objective: Postoperative survival of patients with stage IIIA‐N2 non–small cell lung cancer (NSCLC) is highly heterogeneous. Here, we aimed to identify variables associated with postoperative survival and develop a tool for survival prediction. Methods: A retrospective review was performed in the Surveillance, Epidemiology, and End Results database from January 2004 to December 2009. Significant variables were selected by use of the backward stepwise method. The nomogram was constructed with multivariable Cox regression. The models performance was evaluated by concordance index and calibration curve. The model was validated via an independent cohort from the Jiangsu Cancer Hospital Lung Cancer Center. Results: A total of 1809 patients with stage IIIA‐N2 NSCLC who underwent surgery were included in the training cohort. Age, sex, grade, histology, tumor size, visceral pleural invasion, positive lymph nodes, lymph nodes examined, and surgery type (lobectomy vs pneumonectomy) were identified as significant prognostic variables using backward stepwise method. A nomogram was developed from the training cohort and validated using an independent Chinese cohort. The concordance index of the model was 0.673 (95% confidence interval, 0.654‐0.692) in training cohort and 0.664 in validation cohort (95% confidence interval, 0.614‐0.714). The calibration plot showed optimal consistency between nomogram predicted survival and observed survival. Survival analyses demonstrated significant differences between different subgroups stratified by prognostic scores. Conclusions: This nomogram provided the individual survival prediction for patients with stage IIIA‐N2 NSCLC after surgery, which might benefit survival counseling for patients and clinicians, clinical trial design and follow‐up, as well as postoperative strategy‐making.

CAG repeat polymorphisms in the androgen receptor and breast cancer risk in women: a meta-analysis of 17 studies

The association between polymorphic CAG repeats in the androgen receptor gene in women and breast cancer susceptibility has been studied extensively. However, the conclusions regarding this relationship remain conflicting. The purpose of this meta-analysis was to identify whether androgen receptor CAG repeat lengths were related to breast cancer susceptibility. The MEDLINE, PubMed, and EMBASE databases were searched through to December 2014 to identify eligible studies. Data and study quality were rigorously assessed by two investigators according to the Newcastle-Ottawa Quality Assessment Scale. The publication bias was assessed by the Begg’s test. Seventeen eligible studies were included in this meta-analysis. The overall analysis suggested no association between CAG polymorphisms and breast cancer risk (odds ratio [OR] 1.031, 95% confidence interval [CI] 0.855–1.245). However, in the subgroup analysis, we observed that long CAG repeats significantly increased the risk of breast cancer in the Caucasian population (OR 1.447, 95% CI 1.089–1.992). Additionally, the risk was significantly increased in Caucasian women carrying two alleles with CAG repeats ≥22 units compared with those with two shorter alleles (OR 1.315, 95% CI 1.014–1.707). These findings suggest that long CAG repeats increase the risk of breast cancer in Caucasian women. However, larger scale case-control studies are needed to validate our results.

Diisopropylamine dichloroacetate enhances radiosensitization in esophageal squamous cell carcinoma by increasing mitochondria-derived reactive oxygen species levels

Radiotherapy is generally applied in the treatment of esophageal squamous cell carcinoma (ESCC). However, the radioresistance of ESCC still remains an obstacle for the curative effect of this treatment. We hypothesized that diisopropylamine dichloroacetate (DADA), an inhibitor of pyruvate dehydrogenase kinase (PDK), might enhance radiosensitizationin resistant ESCC. The clonogenic survival assay revealed that DADA sensitized ESCC cells to radiotherapy in vitro; furthermore, the combination of DADA and radiotherapy increased the expression of γ-H2AX, which is a hallmark of DNA double-strand breaks. Arrest at G2/M phase as well as the induction of apoptosis of ESCC cells were also observed in the cells treated with the combination of DADA and radiotherapy. Notably, xenograft tumor growth was significantly suppressed in vivo by combined radiotherapy and DADA administration. It has been proven that glycolysis is highly correlated with radioresistance, which could be reversed by the shift from glycolysis to mitochondrial oxidation. In our present study, we found that DADA could modulate oxidative phosphorylation as well as increase the intracellular levels of reactive oxygen species (ROS). Collectively, we concluded that DADA-induced intracellular ROS accumulation was identified as the key factor of radiotherapy sensitization of ESCC.