PLCE1 Promotes Esophageal Cancer Cell Progression by Maintaining the Transcriptional Activity of Snail

Circular RNAs with protein-coding ability in oncogenesis

As ubiquitously expressed transcripts in eukaryotes, circular RNAs (circRNAs) are covalently closed and lack a 5'-cap and 3'-polyadenylation (poly (A)) tail. Initially, circRNAs were considered non-coding RNA (ncRNA), and their roles as sponging molecules to adsorb microRNAs have been extensively reported. However, in recent years, accumulating evidence has demonstrated that circRNAs could encode functional polypeptides through the initiation of translation mediated by internal ribosomal entry sites (IRESs) or N6-methyladenosine (m6A). In this review, we collectively discuss the biogenesis, cognate mRNA products, regulatory mechanisms, aberrant expression and biological phenotypes or clinical relevance of all currently reported, cancer-relevant protein-coding circRNAs. Overall, we provide a comprehensive overview of circRNA-encoded proteins and their physiological and pathological functions.

Characterizing genes associated with cancer using the CRISPR/Cas9 system: A systematic review of genes and methodological approaches

The CRISPR/Cas9 system enables a versatile set of genomes editing and genetic-based disease modeling tools due to its high specificity, efficiency, and accessible design and implementation. In cancer, the CRISPR/Cas9 system has been used to characterize genes and explore different mechanisms implicated in tumorigenesis. Different experimental strategies have been proposed in recent years, showing dependency on various intrinsic factors such as cancer type, gene function, mutation type, and technical approaches such as cell line, Cas9 expression, and transfection options. However, the successful methodological approaches, genes, and other experimental factors have not been analyzed. We, therefore, initially considered more than 1,300 research articles related to CRISPR/Cas9 in cancer to finally examine more than 400 full-text research publications. We summarize findings regarding target genes, RNA guide designs, cloning, Cas9 delivery systems, cell enrichment, and experimental validations. This analysis provides valuable information and guidance for future cancer gene validation experiments.

HuR Affects the Radiosensitivity of Esophageal Cancer by Regulating the EMT-Related Protein Snail

Purpose

We previously found that Hu antigen R (HuR) can regulate the proliferation and metastasis of esophageal cancer cells. This study aims to explore the effects of HuR on the radiosensitivity of esophageal cancer.

Materials and Method

Analyses of CCK-8, colony formation assay, Western blot, immunofluorescence, flow cytometry, reactive oxygen species (ROS), and mitochondrial membrane potential were conducted to characterize the esophageal cancer cells. Nude mouse models were used to detect the effects of HuR in a combination of X-ray treatment on the subcutaneous xenografts of esophageal cancer. In addition, a luciferase assay was used to detect the direct interaction of HuR with Snail mRNA 3’-UTR.

Results

The down-regulation of HuR combined with X-ray can significantly inhibit the proliferation and colony formation of esophageal cancer cells. Flow cytometry data showed that the down-regulation of HuR could induce a G1 phase cell cycle block in esophageal cancer cells, and aggravate X-ray-induced apoptosis, indicated by the increases of apoptosis-related proteins Bax, caspase-3 and caspase-9. Moreover, the down-regulation of HuR could significantly impair the mitochondrial membrane potential and increase the ROS production and DNA double-strand break marker γH2AX expression in esophageal cancer cells that were exposed to X-rays. In vivo data showed that the down-regulation of HuR combined with radiation significantly decreased the growth of subcutaneous xenograft tumors. Furthermore, HuR could interact with Snail. Up-regulation of Snail can reverse the EMT inhibitory effects caused by HuR down-regulation, and attenuate the tumor-inhibiting and radiosensitizing effects caused by HuR down-regulation.

Conclusion

In summary, our data demonstrate that HuR effectively regulates the radiosensitivity of esophageal cancer, which may be achieved by stabilizing Snail. Thus, HuR/Snail axis is a potentially therapeutic target for the treatment of esophageal cancer.

Overarching roles of diacylglycerol signaling in cancer development and antitumor immunity

Diacylglycerol (DAG) is a lipid second messenger that is generated in response to extracellular stimuli and channels intracellular signals that affect mammalian cell proliferation, survival, and motility. DAG exerts a myriad of biological functions through protein kinase C (PKC) and other effectors, such as protein kinase D (PKD) isozymes and small GTPase-regulating proteins (such as RasGRPs). Imbalances in the fine-tuned homeostasis between DAG generation by phospholipase C (PLC) enzymes and termination by DAG kinases (DGKs), as well as dysregulation in the activity or abundance of DAG effectors, have been widely associated with tumor initiation, progression, and metastasis. DAG is also a key orchestrator of T cell function and thus plays a major role in tumor immunosurveillance. In addition, DAG pathways shape the tumor ecosystem by arbitrating the complex, dynamic interaction between cancer cells and the immune landscape, hence representing powerful modifiers of immune checkpoint and adoptive T cell-directed immunotherapy. Exploiting the wide spectrum of DAG signals from an integrated perspective could underscore meaningful advances in targeted cancer therapy.

CRISPR/Cas9 in Gastrointestinal Malignancies

Gastrointestinal (GI) cancers such as colorectal cancer (CRC), gastric cancer (GC), esophageal cancer (EG), pancreatic duct adenocarcinoma (PDAC) or hepatocellular cancer (HCC) belong to the most commonly diagnosed types of cancer and are among the most frequent causes of cancer related death worldwide. Most types of GI cancer develop in a stepwise fashion with the occurrence of various driver mutations during tumor progression. Understanding the precise function of mutations driving GI cancer development has been regarded as a prerequisite for an improved clinical management of GI malignancies. During recent years, CRISPR/Cas9 has developed into a powerful tool for genome editing in cancer research by knocking in and knocking out even multiple genes at the same time. Within this review, we discuss recent applications for CRISPR/Cas9-based genome editing in GI cancer research including CRC, GC, EG, PDAC and HCC. These applications include functional studies of candidate genes in cancer cell lines or organoids in vitro as well as in murine cancer models in vivo, library screening for the identification of previously unknown driver mutations and even gene therapy of GI cancers.

CircPLCE1 facilitates the malignant progression of colorectal cancer by repressing the SRSF2-dependent PLCE1 pre-RNA splicing

Studies have demonstrated that circular RNAs (circRNAs) play important roles in various types of cancer; however, the mechanisms of circRNAs located in the nucleus have rarely been explored. Here, we report a novel circular RNA circPLCE1 (hsa_circ_0019230) that facilitates the malignant progression of colorectal cancer (CRC) by repressing serine/arginine‐rich splicing factor 2 (SRSF2)‐dependent phospholipase C epsilon 1 (PLCE1) pre‐RNA splicing. Quantitative real‐time polymerase chain reaction was used to determine the expression of circPLCE1 in CRC tissues and cells. Cell Counting Kit‐8, Transwell and flow cytometric assays were used to assess the role of circPLE1 in CRC cell proliferation, migration and apoptosis, respectively. An animal study was conducted to test the role of circPLCE1 in vivo. Furthermore, catRAPID and RPISeq were used to predict the possible binding proteins of circPLCE1. RNA fractionation and RNA immunoprecipitation assays were used to confirm the RNA‐protein interaction. In this study, we found that circPLCE1 was more significantly down‐regulated in CRC tissues compared with that in adjacent normal tissues. However, circPLCE1 knockdown suppressed CRC cell proliferation, migration and invasion and increased apoptosis. Nude mouse experiments showed that ectopic expression of circPLCE1 dramatically increased tumour growth in vivo. Mechanistically, circPLCE1 directly bound to the SRSF2 protein, repressing SRSF2‐dependent PLCE1 pre‐RNA splicing, resulting in the progression of CRC. Individually mutating the binding sites of circPLCE1 abolished the inhibition of PLCE1 mRNA production. Our study revealed a novel molecular mechanism in the regulation of PLCE1 and suggested a new function of circular RNA.

YAP-TEAD up-regulates IRS2 expression to induce and deteriorate oesophageal cancer

Oesophageal cancer (EC) represents a significant cause of cancer worldwide. Yes‐associated protein (YAP) is reported to correlate with the initiation of multiple cancers including EC, but the underlying mechanism remains elusive. The current study aimed to investigate the molecular mechanism of YAP‐TEAD in the occurrence and progression of EC. EC tissues and cells were obtained, followed by determination of the expression of YAP, c‐Jun, pc‐Jun and IRS2. The effect of YAP‐TEAD on the biological EC cell processes was explored through gain‐ and loss‐of‐function approaches. The interaction between YAP and TEAD was detected by co‐immunoprecipitation. The binding of TEAD to the c‐Jun promoter was determined using chromatin immunoprecipitation. Tumour formation in the nude mice was detected in order to ascertain the effect of YAP and IRS2 in vivo. We found elevated YAP in the EC tissues and cells. YAP silencing led to a decrease in EC cell proliferation, invasion and sphere formation. YAP‐TEAD complex bound to the promotor of c‐Jun, and c‐Jun led to an increase in the expression of IRS2 through the JNK/c‐Jun pathway. Additionally, pc‐Jun and phosphorylated JNK were localized in the nuclear in addition to displaying enhanced expression in the EC tissues. IRS2 overexpression negated the inhibition of cell proliferation, invasion and sphere formation triggering YAP silencing. YAP up‐regulated IRS2 and aggravated EC in vivo. Taken together, YAP‐TEAD activates the JNK/c‐Jun pathway to up‐regulate IRS2, ultimately promoting EC progression. Therefore, YAP‐TEAD inhibition could be a promising therapeutic approach for EC treatment.

Identification of a PLCE1‑regulated competing endogenous RNA regulatory network for esophageal squamous cell carcinoma

Phospholipase C epsilon 1 (PLCE1) and the competing endogenous RNA (ceRNA) network are crucial for tumorigenesis and the progression of esophageal squamous cell carcinoma (ESCC). However, whether PLCE1 can regulate the ceRNA network in ESCC has not been clarified. In the present study, we aimed to identify the PLCE1-regulated ceRNA network and further elucidate the regulatory mechanisms by which ESCC is promoted. Microarray analysis was used to identify differentially expressed lncRNAs (DELs) and differentially expressed genes (DEGs) from three pairs of samples of PLCE-silenced Eca109 and control Eca109 cells. Next, the ceRNA regulatory network was established and visualized in Cytoscape, and functional enrichment analysis was performed to analyze DEGs from ceRNAs. Protein-protein interaction (PPI) networks among the DEGs were established by the STRING database to screen hub genes. Kaplan-Meier survival analysis was used to validate hub genes. Finally, PLCE1-related hub gene/lncRNA/miRNA axes were also constructed based on the ceRNA network. A total of 105 DELs and 346 DEGs were found to be dysregulated in the microarray data (|log2FC| >1.5, adjusted P<0.05). We constructed a PLCE1-regulated ceRNA network that incorporated 12 lncRNAs, 43 miRNAs, and 169 mRNAs. Functional enrichment analysis indicated that the DEGs might be associated with ESCC onset and development. A PPI network was established, and 9 hub genes [WD and tetratricopeptide repeats 1 (WDTC1), heat shock protein family A (Hsp70) member 5 (HSPA5), N-ethylmaleimide sensitive factor, vesicle fusing ATPase (NSF), fibroblast growth factor 2 (FGF2), cyclin dependent kinase inhibitor 1A (CDKN1A or P21), bone morphogenetic protein 2 (BMP2), complement C3 (C3), GM2 ganglioside activator (GM2A) and discs large MAGUK scaffold protein 4 (DLG4)] were determined from the network. Kaplan-Meier survival analysis validated four hub genes (BMP2, CDKN1A, GM2A, and DLG4) that were treated as prognostic factors. Ultimately, hub gene/lncRNA/miRNA subnetworks were obtained based on the 4 hub genes, 13 DEmiRNAs, and 10 DELs. In conclusion, the PLCE1-regulated ceRNA contributes to the onset and progression of ESCC and the underlying molecular mechanisms may provide insights into personalized prognosis and new therapies for ESCC patients.

MTA1 promotes tumorigenesis and development of esophageal squamous cell carcinoma via activating the MEK/ERK/p90RSK signaling pathway

Metastasis-associated protein 1 (MTA1) is upregulated in multiple malignancies and promotes cancer proliferation and metastasis, but whether and how MTA1 promotes esophageal squamous cell carcinoma (ESCC) tumorigenesis remain unanswered. Here, we established an ESCC model in MTA1 transgenic mice induced by the chemical carcinogen 4-nitroquinoline 1-oxide (4-NQO) and found that MTA1 promotes ESCC tumorigenesis in mice. MTA1 overexpression was observed in ESCC cells and clinical ESCC samples. Overexpressed MTA1 increased colony formation and the invasiveness and migration of ESCC cells, whereas knock down of MTA1 in ESCC cells significantly decreased colony formation, invasion and migration in vitro and inhibited the growth of xenograft tumors in vivo. RNA sequencing (RNA-seq) analysis combined with western blot assays revealed that MTA1 promotes carcinogenesis by enhancing MEK/ERK/p90RSK signaling. The phosphorylation of MEK, ERK and their downstream target p90RSK was significantly decreased after MTA1 knockdown in ESCC cells and was increased in MTA1-overexpressing cells. Moreover, colony formation, invasion and migration potential were dramatically suppressed when cells overexpressing MTA1 were treated with MEK (PD0325901) or ERK (SCH772948) inhibitors. In conclusion, MTA1 plays a pivotal oncogenic role in ESCC tumorigenesis and development through activating the MEK/ERK/p90RSK pathway.

Regulation of Hippo/YAP signaling and Esophageal Squamous Carcinoma progression by an E3 ubiquitin ligase PARK2

Objective: Esophageal squamous cell carcinoma (ESCC) is one of the most commonly diagnosed cancer types in China. Recent genomic sequencing analysis indicated the over-activation of Hippo/YAP signaling might play important roles for the carcinogenic process and progression for ESCC patients. However, little is known about the molecular mechanisms that controls Hippo signaling activity in ESCC. Our previous studies indicated that PLCE1-an important risk factor for ESCC-linked to ESCC progression through snail signaling, during this period, we found PARK2 was an important downstream target of PLCE1-snail axis. PARK2 was decreased in ESCC human samples, and correlated with good prognosis in ESCC patients. Further research showed that PARK2 could inhibit YAP, which functions as key downstream effectors of the Hippo pathway. Here, we aim to reveal the molecular mechanisms of PARK2 modulated Hippo pathway in ESCC.

Methods: To evaluate the function of PARK2 in ESCC, we used a tissue microarray (TMA) of 223 human ESCC patients and immunohistochemistry to analyze the correlation between PARK2 expression and clinicopathologic variables. Depletion of endogenous PARK2 and YAP from ESCC cells using CRISPR/Cas9 technologies. Flow cytometry and EdU cell proliferation assay were used to detect proliferation of ESCC cells. Nude mice subcutaneous injection and Ki-67 staining were used to evaluate tumor growth in vivo. Migration and invasion assays were performed. In addition, lung metastasis models in mice were used to validate the function of PARK2 in vivo. Identification of PARK2 involved in hippo pathway was achieved by expression microarray screening, double immunofluorescence staining and co-immunoprecipitation assays. The RNA-seq analysis results were validated through quantitative real-time PCR (qRT-PCR) analysis. The protein half-life of YAP was analyzed by Cycloheximide assay, and the TEAD activity was detected by Luciferase reporter assays.

Results: Clinical sample of ESCC revealed that low PARK2 expression correlated with late tumor stage (P < 0.001), poor differentiation (P < 0.04), lymph node (P < 0.001) and distant metastasis (P = 0.0087). Multivariate Cox proportional regression analysis further revealed that PARK2 expression (P = 0.032) is an independent prognostic factor for the overall survival of ESCC patients. Besides, the immunohistochemistry results showed that PARK2 negatively correlated with YAP protein level (P < 0.001). PARK2 depletion promotes ESCC progression both through Hippo/YAP axis, while PARK2 overexpression suppresses ESCC tumor progression by Hippo signaling. Co-IP and ubiquitination assays revealed that PARK2 could interact with YAP in the cytosol and promotes YAP K48-linked ubiquitination at K90 sites.

Conclusion: Clinical sample analysis and mechanistic study have validated PARK2 as a tumor suppressor for ESCC. Multivariate Cox proportional regression analysis further revealed that PARK2 is an independent prognostic factor for the overall survival of ESCC patients. Cellular and molecular mechanisms in this study showed that PARK2 associated with YAP protein in the cytosol, promoted YAP ubiquitination and proteasome-dependent degradation in ESCC cells. Therefore, as a novel modulator for Hippo signaling, modulation of PARK2 activity or gene expression level could be an appealing strategy to treat esophageal.

Meta-analysis of genome-wide association studies and functional assays decipher susceptibility genes for gastric cancer in Chinese populations

OBJECTIVE

Although a subset of genetic loci have been associated with gastric cancer (GC) risk, the underlying mechanisms are largely unknown. We aimed to identify new susceptibility genes and elucidate their mechanisms in GC development.

DESIGN

We conducted a meta-analysis of four genome-wide association studies (GWASs) encompassing 3771 cases and 5426 controls. After targeted sequencing and functional annotation, we performed in vitro and in vivo experiments to confirm the functions of genetic variants and candidate genes. Moreover, we selected 33 promising variants for two-stage replication in 7035 cases and 8323 controls from other five studies.

RESULTS

The meta-analysis of GWASs identified three loci at 1q22, 5p13.1 and 10q23.33 associated with GC risk at p<5×10^-8 and replicated seven known loci at p<0.05. At 5p13.1, the risk rs59133000[C] allele enhanced the binding affinity of NF-κB1 (nuclear factor kappa B subunit 1) to the promoter of PRKAA1, resulting in a reduced promoter activity and lower expression. The knockout of PRKAA1 promoted both GC cell proliferation and xenograft tumour growth in nude mice. At 10q23.33, the rs3781266[C] and rs3740365[T] risk alleles in complete linkage disequilibrium disrupted and created, respectively, the binding motifs of POU2F1 and PAX3, resulting in an increased enhancer activity and expression of NOC3L, while the NOC3L knockdown suppressed GC cell growth. Moreover, two new loci at 3q11.2 (OR=1.21, p=4.56×10^-9) and 4q28.1 (OR=1.14, p=3.33×10^-11) were associated with GC risk.

CONCLUSION

We identified 12 loci to be associated with GC risk in Chinese populations and deciphered the mechanisms of PRKAA1 at 5p13.1 and NOC3L at 10q23.33 in gastric tumourigenesis.

SHARPIN Inhibits Esophageal Squamous Cell Carcinoma Progression by Modulating Hippo Signaling

Esophageal cancer is one of the leading malignancies worldwide, while around sixty percent of newly diagnosed cases are in China. In recent years, genome-wide sequencing studies and cancer biology studies show that Hippo signaling functions a critical role in esophageal squamous cell carcinoma (ESCC) progression, which could be a promising therapeutic targets in ESCC treatment. However, the detailed mechanisms of Hippo signaling dys-regulation in ESCC remain not clear. Here we identify SHARPIN protein as an endogenous inhibitor for YAP protein. SHARPIN depletion significantly decreases cell migration and invasion capacity in ESCC, which effects could be rescued by further YAP depletion. Depletion SHARPIN increases YAP protein level and YAP/TEAD target genes, such as CTGF and CYR61 in ESCC. Immuno-precipitation assay shows that SHARPIN associates with YAP, promoting YAP degradation possibly via inducing YAP K48-dependent poly-ubiquitination. Our study reveals a novel post-translational mechanism in modulating Hippo signaling in ESCC. Overexpression or activation of SHARPIN could be a promising strategy to target Hippo signaling for ESCC patients.

Application of CRISPR/Cas9 gene editing technique in the study of cancer treatment

In recent years, gene editing, especially that using clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9, has made great progress in the field of gene function. Rapid development of gene editing techniques has contributed to their significance in the field of medicine. Because the CRISPR/Cas9 gene editing tool is not only powerful but also has features such as strong specificity and high efficiency, it can accurately and rapidly screen the whole genome, facilitating the administration of gene therapy for specific diseases. In the field of tumor research, CRISPR/Cas9 can be used to edit genomes to explore the mechanisms of tumor occurrence, development, and metastasis. In these years, this system has been increasingly applied in tumor treatment research. CRISPR/Cas9 can be used to treat tumors by repairing mutations or knocking out specific genes. To date, numerous preliminary studies have been conducted on tumor treatment in related fields. CRISPR/Cas9 holds great promise for gene-level tumor treatment. Personalized and targeted therapy based on CRISPR/Cas9 will possibly shape the development of tumor therapy in the future. In this study, we review the findings of CRISPR/Cas9 for tumor treatment research to provide references for related future studies on the pathogenesis and clinical treatment of tumors.

Genetic Variants in EGFR/PLCE1 Pathway Are Associated with Prognosis of Esophageal Squamous Cell Carcinoma after Radical Resection

Esophageal cancer (EC) is one of the most deadly malignant diseases. Several studies revealed that variations of the phospholipase C epsilon 1 (PLCE1) gene were associated with EC susceptibility. PLCE1 is located downstream of the epidermal growth factor receptor (EGFR) pathway. Presently, the single nucleotide polymorphisms (SNPs) of EGFR/PLCE1 genes and their associations with EC survival remain unclear. In this study, the associations between genetic variants in the EGFR/PLCE1 pathway and prognosis in 124 esophageal squamous cell carcinoma (ESCC) patients with radical resection were explored. The results showed that CC genotype of both PLCE1 rs17109671 and EGFR rs2072454 was associated with ESCC prognosis. Multivariate analysis revealed that patients with the two unfavorable genotypes had the worst overall survival (OS) or disease-free survival (DFS) (HR=6.099, 95%CI=1.903-19.552; HR=3.994, 95%CI=1.49-10.702, respectively). Additionally, combination of SNPs and tumor stage could better predict OS (for AUC, 0.774 vs. 0.709) and PFS (for AUC, 0.773 vs. 0.704) than tumor stage alone. In conclusion, genetic variants of the EGFR/PLCE1 may be predictors of the prognosis of ESCC after surgery. The individuals with the CC genotype of PLCE1 rs17109671 and EGFR rs2072454 should receive more aggressive treatments.

MicroRNA-145 performs as a tumor suppressor in human esophageal squamous cell carcinoma by targeting phospholipase C epsilon 1

Esophageal squamous cell carcinoma (ESCC) is the leading pathologic type in China. miR-145 has been reported to be downregulated in multiple tumors. This study was aimed to investigate the role of miR-145 in ESCC. miR-145 expression was investigated in 65 ESCC samples as well as four ESCC cell lines by quantitative real-time polymerase chain reaction (qRT-PCR). Targetscan 6.2 website (http://www.targetscan.org/) was used to predict the targets of miR-145. Expression of phospholipase C epsilon 1 (PLCE1) messenger RNA and protein was detected by qRT-PCR or Western blot. MTT and wound healing assay were conducted to explore the effects of miR-145 on the proliferation and migration of ESCC cell lines, respectively. miR-145 was significantly decreased in ESCC tissues. An inverse correlation between miR-145 and invasion depth and TNM stage were observed. PLCE1 was a direct target of miR-145, and the expression of PLCE1 was inversely correlated with miR-145 expression in ESCC tissues. In addition, overexpression of miR-145 suppressed cell proliferation and migration in ESCC cells. The enforced expression of PLCE1 partially reversed the suppressive effect of miR-145. These results prove that miR-145 may perform as a tumor suppressor in ESCC by targeting PLCE1.

Epigenetically upregulated oncoprotein PLCE1 drives esophageal carcinoma angiogenesis and proliferation via activating the PI-PLCε-NF-κB signaling pathway and VEGF-C/ Bcl-2 expression

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is one of the most lethal malignancies. Neovascularization during tumorigenesis supplies oxygen and nutrients to proliferative tumor cells, and serves as a conduit for migration. Targeting oncogenes involved in angiogenesis is needed to treat organ-confined and locally advanced ESCC. Although the phospholipase C epsilon-1 (PLCE1) gene was originally identified as a susceptibility gene for ESCC, how PLCE1 is involved in ESCC is unclear.

METHODS

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry were used to measure the methylation status of the PLCE1 promoter region. To validate the underlying mechanism for PLCE1 in constitutive activation of the NF-κB signaling pathway, we performed studies using in vitro and in vivo assays and samples from 368 formalin-fixed esophageal cancer tissues and 215 normal tissues with IHC using tissue microarrays and the Cancer Genome Atlas dataset.

RESULTS

We report that hypomethylation-associated up-regulation of PLCE1 expression was correlated with tumor angiogenesis and poor prognosis in ESCC cohorts. PLCE1 can activate NF-κB through phosphoinositide-phospholipase C-ε (PI-PLCε) signaling pathway. Furthermore, PLCE1 can bind p65 and IκBα proteins, promoting IκBα-S32 and p65-S536 phosphorylation. Consequently, phosphorylated IκBα promotes nuclear translocation of p50/p65 and p65, as a transcription factor, can bind vascular endothelial growth factor-C and bcl-2 promoters, enhancing angiogenesis and inhibiting apoptosis in vitro. Moreover, xenograft tumors in nude mice proved that PLCE1 can induce angiogenesis, inhibit apoptosis, and increase tumor aggressiveness via the NF-κB signaling pathway in vivo.

CONCLUSIONS

Our findings not only provide evidence that hypomethylation-induced PLCE1 confers angiogenesis and proliferation in ESCC by activating PI-PLCε-NF-κB signaling pathway and VEGF-C/Bcl-2 expression, but also suggest that modulation of PLCE1 by epigenetic modification or a selective inhibitor may be a promising therapeutic approach for the treatment of ESCC.

The plasma peptides of ovarian cancer

Background

It may be possible to discover new diagnostic or therapeutic peptides or proteins from blood plasma by using liquid chromatography and tandem mass spectrometry to identify, quantify and compare the peptides cleaved ex vivo from different clinical populations. The endogenous tryptic peptides of ovarian cancer plasma were compared to breast cancer and female cancer normal controls, other diseases with their matched or normal controls, plus ice cold plasma to control for pre-analytical variation.

Methods

The endogenous tryptic peptides or tryptic phospho peptides (i.e. without exogenous digestion) were analyzed from 200 μl of EDTA plasma. The plasma peptides were extracted by a step gradient of organic/water with differential centrifugation, dried, and collected over C18 for analytical HPLC nano electrospray ionization and tandem mass spectrometry (LC–ESI–MS/MS) with a linear quadrupole ion trap. The endogenous peptides of ovarian cancer were compared to multiple disease and normal samples from different institutions alongside ice cold controls. Peptides were randomly and independently sampled by LC–ESI–MS/MS. Precursor ions from peptides > E4 counts were identified by the SEQUEST and X!TANDEM algorithms, filtered in SQL Server, before testing of frequency counts by Chi Square (χ²), for analysis with the STRING algorithm, and comparison of precursor intensity by ANOVA in the R statistical system with the Tukey-Kramer Honestly Significant Difference (HSD) test.

Results

Peptides and/or phosphopeptides of common plasma proteins such as HPR, HP, HPX, and SERPINA1 showed increased observation frequency and/or precursor intensity in ovarian cancer. Many cellular proteins showed large changes in frequency by Chi Square (χ² > 60, p < 0.0001) in the ovarian cancer samples such as ZNF91, ZNF254, F13A1, LOC102723511, ZNF253, QSER1, P4HA1, GPC6, LMNB2, PYGB, NBR1, CCNI2, LOC101930455, TRPM5, IGSF1, ITGB1, CHD6, SIRT1, NEFM, SKOR2, SUPT20HL1, PLCE1, CCDC148, CPSF3, MORN3, NMI, XTP11, LOC101927572, SMC5, SEMA6B, LOXL3, SEZ6L2, and DHCR24. The protein gene symbols with large Chi Square values were significantly enriched in proteins that showed a complex set of previously established functional and structural relationships by STRING analysis. Analysis of the frequently observed proteins by ANOVA confirmed increases in mean precursor intensity in ZFN91, TRPM5, SIRT1, CHD6, RIMS1, LOC101930455 (XP_005275896), CCDC37 and GIMAP4 between ovarian cancer versus normal female and other diseases or controls by the Tukey–Kramer HSD test.

Conclusion

Here we show that separation of endogenous peptides with a step gradient of organic/water and differential centrifugation followed by random and independent sampling by LC–ESI–MS/MS with analysis of peptide frequency and intensity by SQL Server and R revealed significant difference in the ex vivo cleavage of peptides between ovarian cancer and other clinical treatments. There was striking agreement between the proteins discovered from cancer plasma versus previous biomarkers discovered in tumors by genetic or biochemical methods. The results indicate that variation in plasma proteins from ovarian cancer may be directly discovered by LC–ESI–MS/MS that will be a powerful tool for clinical research.

Electronic supplementary material

The online version of this article (10.1186/s12014-018-9215-z) contains supplementary material, which is available to authorized users.

RNF168 facilitates proliferation and invasion of esophageal carcinoma, possibly via stabilizing STAT1

Oesophageal cancer ranks as one of the most common malignancy in China and worldwide. Although genome‐wide association studies and molecular biology studies aim to elucidate the driver molecules in oesophageal cancer progression, the detailed mechanisms remain to be identified. Interestingly, RNF168 (RING finger protein 168) shows a high frequency of gene amplification in oesophageal cancer from TCGA database. Here, we report an important function for RNF168 protein in supporting oesophageal cancer growth and invasion by stabilizing STAT1 protein. RNF168 gene is amplified in oesophageal cancer samples, which tends to correlate with poor prognosis. Depletion RNF168 causes decreased cell proliferation and invasion in oesophageal cancer cells. Through unbiased RNA sequencing in RNF168 depleted oesophageal cancer cell, we identifies JAK‐STAT pathway is dramatically decreased. Depletion RNF168 reduced JAK‐STAT target genes, such as IRF1, IRF9 and IFITM1. Immuno‐precipitation reveals that RNF168 associates with STAT1 in the nucleus, stabilizing STAT1 protein and inhibiting its poly‐ubiquitination and degradation. Our study provides a novel mechanism that RNF168 promoting JAK‐STAT signalling in supporting oesophageal cancer progression. It could be a promising strategy to target RNF168 for oesophageal cancer treatment.

PLCE1 Promotes the Invasion and Migration of Esophageal Cancer Cells by Up-Regulating the PKCα/NF-κB Pathway

PURPOSE

To investigate the effect and mechanism of phospholipase C epsilon gene 1 (PLCE1) expression on esophageal cancer cell lines.

MATERIALS AND METHODS

The esophageal carcinoma cell lines Eca109 and EC9706 and normal esophageal epithelial cell line HEEC were cultured. The expression of PLCE1, protein kinase C alpha (PKCα), and nuclear factor kappa B (NF-κB) p50/p65 homodimer in cells were comparatively analyzed. The esophageal cancer cells were divided into si-PLCE1, control siRNA (scramble), and mock groups that were transfected with specific siRNA for PLCE1, control siRNA, and blank controls, respectively. Expression of PLCE1, PKCα, p50, and p65 was detected by Western blotting. Transwell assay was used to detect migration and invasion of Eca109 and EC9706 cells.

RESULTS

Compared with HEEC, the expression of PLCE1, PKCα, p50, and p65 was increased in Eca109 and EC9706 cells. The expression of PLCE1 was positively correlated with the expression of PKCα and p50 (PKCα: r=0.6328, p=0.032; p50: r=0.6754, p=0.041). PKCα expression had a positive correlation with the expression of p50 and p65 (p50: r=0.9127, p=0.000; p65: r=0.9256, p=0.000). Down-regulation of PLCE1 significantly decreased the expression of PKCα and NF-κB-related proteins (p65: p=0.002, p=0.004; p50: p=0.005, p=0.009) and inhibited the migration and invasion of Eca109 and EC9706 cells.

CONCLUSION

PLCE1 activated NF-κB signaling by up-regulating PKCα, which could promote invasion and migration of esophageal cancer cells.

Regulatory mechanisms of miR-145 expression and the importance of its function in cancer metastasis

MicroRNAs are post-transcriptional mediators of gene expression and regulation, which play influential roles in tumorigenesis and cancer metastasis. The expression of tumor suppressor miR-145 is reduced in various cancer cell lines, containing both solid tumors and blood malignancies. However, the responsible mechanisms of its down-regulation are a complicated network. miR-145 is potentially able to inhbit tumor cell metastasis by targeting of multiple oncogenes, including MUC1, FSCN1, Vimentin, Cadherin, Fibronectin, Metadherin, GOLM1, ARF6, SMAD3, MMP11, Snail1, ZEB1/2, HIF-1α and Rock-1. This distinctive role of miR-145 in the regulation of metastasis-related gene expression may introduce miR-145 as an ideal candidate for controlling of cancer metastasis by miRNA replacement therapy. The present review aims to discuss the current understanding of the different aspects of molecular mechanisms of miR-145 regulation as well as its role in r metastasis regulation.

Evaluation of GWAS-Identified Genetic Variants for Gastric Cancer Survival

BACKGROUNDS

Genome-wide association studies (GWASs) have identified several gastric cancer (GC) susceptibility loci in Asians, but their effects on disease outcome are still unknown. This study aimed to investigate whether these GWAS-identified genetic variants could serve as robust prognostic biomarkers for GC.

METHODS

A multistage clinical cohort, including a total of 2432 GC patients in the Chinese population, was used to identify the association between GWAS-identified risk variants and overall survival of GC. Hazard ratios (HRs) and 95% confidence intervals (CIs) were computed by Cox regression analysis, and the log-rank P was calculated by the log-rank test with the Kaplan-Meier method.

RESULTS

We found that rs2274223 A>G in PLCE1 was associated with increased GC survival in both training set (P = .011), which was independently replicated in validation set 1 (P = .045), but not in validation set 2. The area under the curve (AUC) from receiver-operator characteristic (ROC) curve showed this clinical relevance with onset age-dependence, especially in the subgroup of early-onset cases. Moreover, a significant improvement in overall survival prediction was identified when the rs2274223 genetic effect was included in the estimation; this result was also supported by the prognostic nomogram. In addition, patients with lower expression of PLCE1 showed benefits via longer survival, potentially due to the functional effect of rs2274223.

INTERPRETATION

This preliminary study suggests that a GWAS-identified genetic variant in PLCE1 may serve as a potential biomarker for GC survival. Additional replication with larger samples size is warranted to further investigation.

Ablation of MCM10 using CRISPR/Cas9 restrains the growth and migration of esophageal squamous cell carcinoma cells through inhibition of Akt signaling

Introduction

Minichromosome maintenance 10 (MCM10) is deregulated in several malignancies including cervical cancer and urothelial carcinoma. However, the expression and biologic role of MCM10 in esophageal squamous cell carcinoma (ESCC) is still unknown.

Methods

In this study, we performed immunohistochemistry and real-time polymerase chain reaction (PCR) analysis to examine the expression of MCM10 in ESCC and adjacent normal esophageal tissues. The associations of MCM10 expression with clinicopathologic parameters of ESCC were analyzed. Ablation of MCM10 through the CRISPR/Cas9 technology was conducted and its impact on ESCC cell growth and migration was investigated.

Results

The mRNA and protein expression levels of MCM10 were significantly greater in ESCC than in normal tissues (P<0.001). The expression of MCM10 was significantly associated with age at diagnosis (P=0.033), but not with gender, differentiation grade, invasion status, or tumor–node–metastasis (TNM) stage. Knockout of MCM10 significantly suppressed the proliferation, colony formation, and migration capacity of EC109 ESCC cells, compared to control cells harboring wild-type MCM10. Mechanistically, MCM10 depletion markedly reduced the phosphorylation of Akt. Overexpression of constitutively active Akt significantly restored the aggressive phenotype of MCM10-null EC109 cells.

Conclusion

In conclusion, these results suggest that MCM10 acts as an oncogene in ESCC through activation of Akt signaling and represents a promising therapeutic target for this malignancy.