An NF-κB/OVOL2 circuit regulates glucose import and cell survival in non-small cell lung cancer.

BACKGROUND: Tumor cells tend to utilize glycolysis rather than aerobic respiration even under aerobic conditions. OVOL2, an inhibitory C2H2 zinc finger transcription factor, is a potential tumor suppressor in cancers. However, the association between OVOL2 and tumor energy metabolism is unknown. METHODS: Western blotting was used to determine the expression of OVOL2 in different non-small cell lung cancer (NSCLC) cell lines and mouse models. The metabolic parameters in NSCLC cells following overexpression or knockdown OVOL2 were examined. To define the mechanism by which OVOL2 regulates aerobic glycolysis, interacting protein of OVOl2 and downstream molecular events were identified by luciferase assay and co-immunoprecipitation. We documented the regulatory mechanism in mouse xenograft models. Finally, clinical relevance of OVOL2, NF-κB signaling and GLUT1 was measured by immunostaining. RESULTS: OVOL2 is downregulated in NSCLC and overexpression of OVOL2 inhibits the survival of cancer cells. Moreover, OVOL2 directly binds to P65 and inhibits the recruitment of P300 but facilitates the binding of HDAC1 to P65, which in turn negatively regulates NF-κB signaling to suppress GLUT1 translocation and glucose import. In contrast, OVOL2 expression is negatively regulated by NF-κB signaling in NSCLC cells via the ubiquitin-proteasome pathway. Re-expression of OVOL2 significantly compromise NF-κB signaling-induced GLUT1 translocation, aerobic glycolysis in NSCLC cells and mouse models. Immunostaining revealed inverse correlations between the OVOL2 and phosphorylated P65 levels and between the OVOL2 and membrane GLUT1 levels, and a strong correlation between the phosphorylated P65 and membrane GLUT1 levels. CONCLUSIONS: These results suggest a regulatory circuit linking NF-κB and OVOL2, which highlights the role of NF-κB signaling and OVOL2 in the modulation of glucose metabolism in NSCLC. Video Abstract.

Inhibition of Bcl6b promotes gastric cancer by amplifying inflammation in mice.

BACKGROUND: Chronic gastritis has been demonstrated to be a key cause of gastric cancer (GC), and control of gastric inflammation is regarded as an effective treatment for the clinical prevention of gastric carcinogenesis. However, there remains an unmet need to identify the dominant regulators of gastric oncogenesis-associated inflammation in vivo. METHODS: The mouse model for the study of inflammation-associated GC was induced by Benzo[a]pyrene (BaP) intragastric administration in Bcl6b-/- and wildtype mice on a C57BL/6 background. 5-Aza-2'-deoxycytidine (5-Aza), the demethylation drug, was intraperitoneally injected to restore Bcl6b expression. Human GC tissue array was used to analyse patient survival based on BCL6B and CD3 protein expression. RESULTS: Bcl6b was gradually downregulated by its own promoter hypermethylation in parallel to an increasing inflammatory response during the progression of BaP-induced gastric carcinogenesis in mice. Moreover, knockout of Bcl6b dramatically worsened the severity of gastric cancer and aggravated the inflammatory response in the BaP-induced mice GC model. Re-activation of Bcl6b by 5-Aza impeded inflammatory amplification and BaP-induced GC development, prolonging survival time in wildtype mice, whereas no notable curative effect occurred in Bcl6b-/- mice with 5-Aza treatment. Finally, significant negative correlations were detected between the mRNA levels of BCL6B and inflammatory cytokines in human GC tissues; patients harbouring BCL6B-negetive and severe-inflammation GC tumours were found to exhibit the shortest survival time. CONCLUSIONS: Epigenetic inactivation of Bcl6b promotes gastric cancer through amplification of the gastric inflammatory response in vivo and offers a new approach for GC treatment and regenerative medicine.

Tumor-originated exosomal lncUEGC1 as a circulating biomarker for early-stage gastric cancer.

Conventional tumor markers for non-invasive diagnosis of gastric cancer (GC) exhibit insufficient sensitivity and specificity to facilitate detection of early gastric cancer (EGC). We aimed to identify EGC-specific exosomal lncRNA biomarkers that are highly sensitive and stable for the non-invasive diagnosis of EGC. Hence, in the present study, exosomes from the plasma of five healthy individuals and ten stage I GC patients and from culture media of four human primary stomach epithelial cells and four gastric cancer cells (GCCs) were isolated. Exosomal RNA profiling was performed using RNA sequencing to identify EGC-specific exosomal lncRNAs. A total of 79 and 285 exosomal RNAs were expressed at significantly higher levels in stage I GC patients and GCCs, respectively, than that in normal controls. Through combinational analysis of the RNA sequencing results, we found two EGC-specific exosomal lncRNAs, lncUEGC1 and lncUEGC2, which were further confirmed to be remarkably up-regulated in exosomes derived from EGC patients and GCCs. Furthermore, stability testing demonstrates that almost all the plasma lncUEGC1 was encapsulated within exosomes and thus protected from RNase degradation. The diagnostic accuracy of exosomal lncUEGC1 was evaluated, and lncUEGC1 exhibited AUC values of 0.8760 and 0.8406 in discriminating EGC patients from healthy individuals and those with premalignant chronic atrophic gastritis, respectively, which was higher than the diagnostic accuracy of carcinoembryonic antigen. Consequently, exosomal lncUEGC1 may be promising in the development of highly sensitive, stable, and non-invasive biomarkers for EGC diagnosis.

Efficient isolation and proteomic analysis of cell plasma membrane proteins in gastric cancer reveal a novel differentiation and progression related cell surface marker, R-cadherin.

Cell plasma membrane proteins, playing a crucial role in cell malignant transformation and development, were the main targets of tumor detection and therapy. In this study, CyDye/biotin double-labeling proteomic approach was adopted to profile the membrane proteome of gastric cancer cell line BGC-823 and paired immortalized gastric epithelial cell GES-1. Real-time PCR, Western blotting, and immunohistochemical staining were used to validate the differential expression of a novel identified cell surface marker R-cadherin in gastric cancer cells and tissues. Clinicopathological study and survival analysis were performed to estimate its roles in tumor progression and outcome prediction. Real-time PCR and Western blotting showed that the expression level of R-cadherin in gastric cancer were significantly lower than non-cancerous epithelial cell and tissues. Clinicopathological study indicated that R-cadherin was dominantly expressed on cell surface of normal gastric epithelium, and its expression deletion in gastric cancer tissues was associated with tumor site, differentiation, lymph node metastasis, and pTNM (chi-square test, P < 0.05). Those patients with R-cadherin positive expression displayed better overall survivals than negative expression group (log-rank test, P = 0.000). Cox multivariate survival analysis revealed lacking the expression of R-cadherin was a main independent predictor for poor clinical outcome in gastric cancer (RR = 5.680, 95 % CI 2.250-14.341, P < 0.01). We have established a fundamental membrane proteome database for gastric cancer and identified R-cadherin as a tumor differentiation and progression-related cell surface marker of gastric cancer. Lacking the expression of R-cadherin indicates poor prognosis in patients with gastric cancer.

CELSR1 Is a Positive Regulator of Endothelial Cell Migration and Angiogenesis.

Cadherin is an epidermal growth factor and laminin-G seven-pass G-type receptor 1 (CELSR1) is a key component of the noncanonical Wnt/planar cell polarity (PCP) pathway that critically regulates endothelial cell proliferation and angiogenesis. In this study, we examined the biological significance of CELSR1 in endothelial cell migration and angiogenesis. For this, we applied both gain-of-function and loss-of-function approaches. To increase the endogenous expression of CELSR1, we used the transcription activator-like effector (TALE) technology and constructed an artificial TALE-VP64 activator. To knock down the expression of CELSR1, we generated lentivirus containing short hairpin RNA sequences targeting different regions of CELSR1 mRNA. Following up- or down-regulation of CELSR1 in human aortic endothelial cells (HAEC), we assessed in vitro cell proliferation by MTT assay, migration by scratch and transwell migration assays, and angiogenesis by tube formation analysis. We found that CELSR1 was endogenously expressed in human umbilical vein endothelial cells (HUVEC) and HAEC. When focusing on HAEC, we found that upregulating CELSR1 expression significantly promoted cell growth, while knocking down CELSR1 inhibited the growth (p < 0.05). Using both scratch and transwell migration assays, we observed a positive correlation between CELSR1 expression and cell migratory capability. In addition, CELSR1 upregulation led to higher levels of tube formation in HAEC, while downregulating CELSR1 expression decreased tube formation (p < 0.05). Mechanistically, CELSR1-regulated migration and tube formation was mediated through disheveled segment polarity protein 3 (Dvl3). In conclusion, CELSR1 plays an important role in regulating multiple phenotypes of endothelial cells, including proliferation, migration, and formation of capillary-like structures.

The Wnt-ß-catenin pathway represses let-7 microRNA expression through transactivation of Lin28 to augment breast cancer stem cell expansion.

Wnt signalling through ß-catenin and the lymphoid-enhancing factor 1/T-cell factor (LEF1/TCF) family of transcription factors maintains stem cell properties in both normal and malignant tissues; however, the underlying molecular pathway involved in this process has not been completely defined. Using a microRNA microarray screening assay, we identified let-7 miRNAs as downstream targets of the Wnt-ß-catenin pathway. Expression studies indicated that the Wnt-ß-catenin pathway suppresses mature let-7 miRNAs but not the primary transcripts, which suggests a post-transcriptional regulation of repression. Furthermore, we identified Lin28, a negative let-7 biogenesis regulator, as a novel direct downstream target of the Wnt-ß-catenin pathway. Loss of function of Lin28 impairs Wnt-ß-catenin-pathway-mediated let-7 inhibition and breast cancer stem cell expansion; enforced expression of let-7 blocks the Wnt-ß-catenin pathway-stimulated breast cancer stem cell phenotype. Finally, we demonstrated that the Wnt-ß-catenin pathway induces Lin28 upregulation and let-7 downregulation in both cancer samples and mouse tumour models. Moreover, the delivery of a modified lin28 siRNA or a let-7a agomir into the premalignant mammary tissues of MMTV-wnt-1 mice resulted in a complete rescue of the stem cell phenotype driven by the Wnt-ß-catenin pathway. These findings highlight a pivotal role for Lin28/let-7 in Wnt-ß-catenin-pathway-mediated cellular phenotypes. Thus, the Wnt-ß-catenin pathway, Lin28 and let-7 miRNAs, three of the most crucial stem cell regulators, connect in one signal cascade.

[Relationship between the expression level of miR-29c and biological behavior of gastric cancer].

OBJECTIVE: To study the function and clinicopathological significance of RNA-29c (miR-29c) in the carcinogenesis and development of gastric cancer. METHODS: MicroRNA microarray was applied to assess the miRNAs expression profile of gastric cancer. Quantitative real-time PCR was used to detect the expression of miR-29c in 64 cases of gastric cancer tissues and corresponding normal gastric epithelium, as well as cell lines GES-1, BGC-823 and SGC-7901 cells. MTT assay and flow cytometry were applied to detect the effects of forced expression of miR-29c in gastric cancer BGC-823 cells including cell proliferation, apoptosis, cell cycle and drug sensitivity. Quantitative real-time PCR, Western blot and luciferase reporter assay were used to explore the targeted relationship between miR-29c and myeloid cell leukemia-1 (Mcl-1). RESULTS: Compared with normal gastric epithelium, seven microRNAs (miR-374b*, miRPlus-E1212, miR-338-5p, miR-297, miR-21, miR-135b, miR-18a) were significantly up-regulated more than 2-folds, and nine microRNAs (miR-29b-2*, miR-1260, miRPlus-E1241, miR-S1-5p, miR-148a, miR-29c, miR-647, miR-196b*, ebv-miR-BART5) were significantly down-reguated in gastric cancer tissues. The average expression level of miR-29c in gastric cancer tissues was 0.70 ± 0.34 and in corresponding normal epithelium was 1.00 ± 0.06 (P < 0.05). miR-29c expression was related to tumor size, lymph node metastasis, clinical stage, Laurén classification, Borrmann classification and Ming classification (P < 0.05). The poorer differentiation degree of gastric cell lines, the lower was miR-29c expression level (P < 0.05). Overexpression of miR-29c in gastric cancer BGC-823 cells suppressed cell proliferation, stimulated cell apoptosis, induced cell cycle arrest in S phase and increased the chemotherapy sensitivity to drug docetaxel (all were P < 0.05). The average expression level of Mcl-1 mRNA in gastric cancer tissues was 3.47 ± 1.34 and corresponding epithelialium was 1.00 ± 0.20 (P < 0.05). The expression level of miR-29c was negatively related with that of Mcl-1 mRNA in gastric cancer tissues. miR-29c directly targeted to regulation of Mcl-1 expression. CONCLUSIONS: There are special miRNA expression profile in gastric cancer. The expression of miR-29c is closely related to biological behavior of human gastric cancer. miR-29c is involved in targeted regulation of Mcl-1, and may be one of mechanisms of the carcinogenesis of gastric cancer.

Identification of a Tumor Microenvironment-relevant Gene set-based Prognostic Signature and Related Therapy Targets in Gastric Cancer.

Rationale: The prognosis of gastric cancer (GC) patients is poor, and there is limited therapeutic efficacy due to genetic heterogeneity and difficulty in early-stage screening. Here, we developed and validated an individualized gene set-based prognostic signature for gastric cancer (GPSGC) and further explored survival-related regulatory mechanisms as well as therapeutic targets in GC. Methods: By implementing machine learning, a prognostic model was established based on gastric cancer gene expression datasets from 1699 patients from five independent cohorts with reported full clinical annotations. Analysis of the tumor microenvironment, including stromal and immune subcomponents, cell types, panimmune gene sets, and immunomodulatory genes, was carried out in 834 GC patients from three independent cohorts to explore regulatory survival mechanisms and therapeutic targets related to the GPSGC. To prove the stability and reliability of the GPSGC model and therapeutic targets, multiplex fluorescent immunohistochemistry was conducted with tissue microarrays representing 186 GC patients. Based on multivariate Cox analysis, a nomogram that integrated the GPSGC and other clinical risk factors was constructed with two training cohorts and was verified by two validation cohorts. Results: Through machine learning, we obtained an optimal risk assessment model, the GPSGC, which showed higher accuracy in predicting survival than individual prognostic factors. The impact of the GPSGC score on poor survival of GC patients was probably correlated with the remodeling of stromal components in the tumor microenvironment. Specifically, TGFß and angiogenesis-related gene sets were significantly associated with the GPSGC risk score and poor outcome. Immunomodulatory gene analysis combined with experimental verification further revealed that TGFß1 and VEGFB may be developed as potential therapeutic targets of GC patients with poor prognosis according to the GPSGC. Furthermore, we developed a nomogram based on the GPSGC and other clinical variables to predict the 3-year and 5-year overall survival for GC patients, which showed improved prognostic accuracy than clinical characteristics only. Conclusion: As a tumor microenvironment-relevant gene set-based prognostic signature, the GPSGC model provides an effective approach to evaluate GC patient survival outcomes and may prolong overall survival by enabling the selection of individualized targeted therapy.

Chibby suppresses aerobic glycolysis and proliferation of nasopharyngeal carcinoma via the Wnt/ß-catenin-Lin28/let7-PDK1 cascade.

BACKGROUND: Great progress has been achieved in the study of the aerobic glycolysis or the so-called Warburg effect in a variety of cancers; however, the regulation of the Warburg effect in Nasopharyngeal carcinoma (NPC) has not been completely defined. METHODS: Gene expression pattern of NPC cells were used to test associations between Chibby and ß-catenin expression. Chibby siRNAs and over-expression vector were transfected into NPC cells to down-regulate or up-regulate Chibby expression. Loss- and gain-of function assays were performed to investigate the role of Chibby in NPC cells. Western blot, cell proliferation, Glucose uptake, Lactate release, ATP level, and O2 consumption assays were used to determine the mechanism of Chibby regulation of underlying targets. Finally, immunohistochemistry assay of fresh NPC and nasopharyngeal normal tissue sample were used to detect the expression of Chibby, ß-Catenin, and PDK1 by immunostaining. RESULTS: We observed that Chibby, a ß-catenin-associated antagonist, is down-regulated in nasopharyngeal carcinoma cell lines and inhibits Wnt/ß-Catenin signaling induced Warburg effect. Mechanism study revealed that Chibby regulates aerobic glycolysis in NPC cells through pyruvate dehydrogenase kinase 1(PDK1), an important enzyme involved in glucose metabolism. Moreover, Chibby suppresses aerobic glycolysis of NPC via Wnt/ß-Catenin-Lin28/let7-PDK1 cascade. Chibby and PDK1 are critical for Wnt/ß-Catenin signaling induced NPC cell proliferation both in vitro and in vivo. Finally, immunostaining assay of tissue samples provides an important clinical relevance among Chibby, Wnt/ß-Catenin signaling and PDK1. CONCLUSIONS: Our study reveals an association between Chibby expression and cancer aerobic glycolysis, which highlights the importance of Wnt/ß-catenin pathway in regulation of energy metabolism of NPC. These results indicate that Chibby and PDK1 are the potential target for NPC treatment.

Aldose reductase interacts with AKT1 to augment hepatic AKT/mTOR signaling and promote hepatocarcinogenesis.

Marked up-regulation of aldose reductase (AR) is reportedly associated with the development of hepatocellular carcinoma (HCC). We investigated how aberrantly overexpressed AR might promote oncogenic transformation in liver cells and tissues. We found that overexpressed AR interacted with the kinase domain of AKT1 to increase AKT/mTOR signaling. In both cultured liver cancer cells and liver tissues in DEN-induced transgenic HCC model mice, we observed that AR overexpression-induced AKT/mTOR signaling tended to enhance lactate formation and hepatic inflammation to enhance hepatocarcinogenesis. Conversely, AR knockdown suppressed lactate formation and inflammation. Using cultured liver cancer cells, we also demonstrated that AKT1 was essential for AR-induced dysregulation of AKT/mTOR signaling, metabolic reprogramming, antioxidant defense, and inflammatory responses. These findings suggest that aberrantly overexpressed/over-activated hepatic AR promotes HCC development at least in part by interacting with oncogenic AKT1 to augment AKT/mTOR signaling. Inhibition of AR and/or AKT1 might serve as an effective strategy for the prevention and therapy of liver cancer.

Establishment and characterization of an expanding-type gastric cancer cell line by Ming's classification.

According to Ming's classification, gastric cancer (GC) can be divided into two types: expanding and infiltrative. The two types are readily recognizable by histology: expanding carcinomas grow en masse and by expansion, resulting in the formation of discrete tumour nodules, whereas in infiltrative carcinoma, tumour cells invade individually. Both types show varying degrees of cell maturation. The two types of carcinomas have vastly different pathological and clinical features. However, little is known concerning the mechanisms underlying these differences since no GC cell line models are available. For comprehensive and insightful analyses of mechanisms and treatment methods, new cell lines derived from expanding- and infiltrative-type gastric tumours are urgently needed. In the present study, we established an expanding-type GC cell line from a 72-year-old male patient. Different in vitro and in vivo methods were used to characterize the phenotypes of this cell line. This GC cell line was named XGC-2 and had an ~60 h doubling time. The cell line displayed strong colony formation and tumourigenicity in nude mice and had complicated chromosomal abnormalities. XGC-2 cells showed some markers of epithelial-to-mesenchymal transition (EMT), with decreased E-cadherin expression levels and increased vimentin expression levels. The XGC-2 cell line may be useful for future studies of GC development, progression, metastasis and therapy.

Reverse Correlation between MicroRNA-145 and FSCN1 Affecting Gastric Cancer Migration and Invasion.

MicroRNAs (miRs) play important roles in modulating gene expression during the processes of tumorigenesis and tumor development. Previous studies have found that miR-145 is down-regulated in the stomach neoplasm and is related to tumor migration and invasion. However, both the molecular mechanism and function of miR-145 in gastric cancer remain unclear. The present study is the first demonstration of the significant down-regulation of miR-145 expression in infiltrative gastric cancer compared to expanding gastric cancer. Additionally, correlation analyses revealed strong inverse correlations between miR-145 and FSCN1 expression levels in infiltrative gastric cancer. Furthermore, we demonstrated that miR-145 directly targets FSCN1 and suppresses cell migration and invasion in gastric cancer. Knocking down the expression of FSCN1 led to the suppression of migration and invasion in gastric cancer cells, and re-expressing FSCN1 in miR-145-overexpressing cells reversed their migration and invasion defects. Thus, we concluded that miR-145 regulates cell migration and invasion in gastric cancer primarily by directly targeting FSCN1.

Prognostic value of SATB2 expression in patients with esophageal squamous cell carcinoma.

SATB2, a member of the family of special AT-rich binding proteins, has been shown to affect numerous tumorigenesis. However, the role of SATB2 in esophageal squamous cell carcinoma (ESCC) remains unclear. In this study, the SATB2 expression was examined at mRNA and protein levels by quantitative real-time reverse transcriptase-polymerase chain reaction (qRT-PCR), Western blotting, and immunohistochemistry in ESCC tissues and adjacent non-cancerous tissues. Statistical analyses were applied to test the associations between SATB2 expression, clinicopathologic factors, and prognosis. Western blotting and qRT-PCR showed that the expression levels of SATB2 mRNA and protein were both significantly lower in SATB2 tissues than those in non-cancerous tissues. Immunohistochemistry analysis showed that SATB2 expression was significantly correlated with clinical stage and Histological differentiation. The results of Kaplan-Meier analysis indicated that a low expression level of SATB2 resulted in a significantly poor prognosis of ESCC patients. Importantly, multivariate analysis showed that low SATB2 expression was an independent prognostic factor for ESCC patients. In sum, our data suggest that SATB2 plays an important role in ESCC progression, and that decreased expression of SATB2 in tumor tissues could be used as a potential prognostic marker for patients with ESCC.