Summary Epigenetic alterations, including DNA methylation and histone modifications, are involved in the regulation of cancer initiation and progression. SET and MYND domain-containing protein 3 ...(SMYD3), a methyltransferase, plays an important role in transcriptional regulation during human cancer progression. However, SMYD3 expression and its function in esophageal squamous cell carcinoma (ESCC) remain unknown. In this study, SMYD3 expression was studied by immunohistochemistry in a tumor tissue microarray from 131 cases of ESCC patients. Statistical analysis showed that overall survival of patients with high SMYD3 expressing in primary tumors was significantly lower than that of patients with low SMYD3-expressing tumors ( P = .008, log-rank test). Increased expression of SMYD3 was found to be associated with lymph node metastasis in ESCC ( P = .036) and was an independent prognostic factor for poor overall survival ( P = .025). RNAi-mediated knockdown of SMYD3 suppressed ESCC cell proliferation, migration, and invasion in vitro and inhibited local tumor invasion in vivo. SMYD3 regulated transcription of EZR and LOXL2 by directly binding to the sequences of the promoter regions of these target genes, as demonstrated by a chromatin immunoprecipitation assay. Immunohistochemical staining of ESCC tissues also confirmed that protein levels of EZR and LOXL2 positively correlated with SMYD3 expression, and the Spearman correlation coefficients ( rs ) were 0.78 (n = 81; P < .01) and 0.637 (n = 103; P < .01), respectively. These results indicate that SMYD3 enhances tumorigenicity in ESCC through enhancing transcription of genes involved in proliferation, migration, and invasion.
Desmosomes are intercellular adhesion complexes involved in various aspects of epithelial pathophysiology, including tissue homeostasis, morphogenesis, and disease development. Recent studies have ...reported that the abnormal expression of various desmosomal components correlates with tumor progression and poor survival. In addition, desmosomes have been shown to act as a signaling platform to regulate the proliferation, invasion, migration, morphogenesis, and apoptosis of cancer cells. The occurrence and progression of head and neck cancer (HNC) is accompanied by abnormal expression of desmosomal components and loss of desmosome structure. However, the role of desmosomal components in the progression of HNC remains controversial. This review aims to provide an overview of recent developments showing the paradoxical roles of desmosomal components in tumor suppression and promotion. It offers valuable insights for HNC diagnosis and therapeutics development.
•We have identified a novel splice variant of lysyl oxidase-like 2, termed LOXL2Δ72.•LOXL2Δ72 has the same N- and C-termini as wild-type LOXL2, but lacks 72 nucleotides encoding 24 amino ...acids.•LOXL2Δ72 is no longer secreted, and enzymatic activity is very low.•LOXL2Δ72 promotes ESCC cell migration and invasion to a greater degree than LOXL2WT.•LOXL2Δ72 may contribute to tumor progression via novel molecular mechanisms.
Lysyl oxidase-like 2 (LOXL2) is a member of the lysyl oxidase family, which plays an important role in extracellular matrix protein biosynthesis and tumor progression. In the present study, we identified a novel splice variant, LOXL2Δ72, which encodes a peptide having the same N- and C-termini as wild-type LOXL2 (LOXL2WT), but lacks 72 nucleotides encoding 24 amino acids. LOXL2Δ72 had dramatically reduced enzymatic activity, and was no longer secreted. However, LOXL2Δ72 promoted greater cell migration and invasion than LOXL2WT. Furthermore, a dual luciferase reporter assay indicated that LOXL2Δ72 activates distinct signal transduction pathways compared to LOXL2WT, consistent with cDNA microarray data showing different expression levels of cell migration- and invasion-related genes induced following over-expression of each LOXL2 isoform. In particular, LOXL2Δ72 distinctly promoted esophageal squamous cell carcinoma (ESCC) cell migration via up-regulating the C-C motif chemokine ligand 28 (CCL28). Our results suggest that the new LOXL2 splice variant contributes to tumor progression by novel molecular mechanisms different from LOXL2WT.
Current staging is inadequate for predicting clinical outcome of esophageal squamous cell carcinoma (ESCC). Aberrant expression of LOXL2 and actin‐related proteins plays important roles in ESCC. ...Here, we aimed to develop a novel molecular signature that exceeds the power of the current staging system in predicting ESCC prognosis. We found that LOXL2 colocalized with filamentous actin in ESCC cells, and gene set enrichment analysis (GSEA) showed that LOXL2 is related to the actin cytoskeleton. An ESCC‐specific protein–protein interaction (PPI) network involving LOXL2 and actin‐related proteins was generated based on genome‐wide RNA‐seq in 15 paired ESCC samples, and the prognostic significance of 14 core genes was analyzed. Using risk score calculation, a three‐gene signature comprising LOXL2, CDH1, and FN1 was derived from transcriptome data of patients with ESCC. The high‐risk three‐gene signature strongly correlated with poor prognosis in a training cohort of 60 patients (P = 0.003). In mRNA and protein levels, the prognostic values of this signature were further validated in 243 patients from a testing cohort (P = 0.001) and two validation cohorts (P = 0.021, P = 0.007). Furthermore, Cox regression analysis revealed that the signature was an independent prognostic factor. Compared with using the signature or TNM stage alone, the combined model significantly enhanced the accuracy in evaluating ESCC prognosis. In conclusion, our data reveal that the tumor‐promoting role of LOXL2 in ESCC is mediated by perturbing the architecture of actin cytoskeleton through its PPIs. We generated a novel three‐gene signature (PPI interfaces) that robustly predicts poor clinical outcome in ESCC patients.
LOXL2 forms an interaction network with actin‐related proteins in ESCC. The three‐gene signature (LOXL2, CDH1, and FN1) exceeds the power of the current staging system in evaluating ESCC prognosis. The high performance of the signature was validated in mRNA and protein levels among three cohorts of patients.
Lysyl oxidase-like 2 (LOXL2), a copper-dependent enzyme of the lysyl oxidase family and its nonsecreted, catalytically dead spliced isoform L2Δ13, enhance cell migration and invasion, stimulate ...filopodia formation, modulate the expression of cytoskeletal genes, and promote tumor development and metastasis
. We previously showed that LOXL2 reorganizes the actin cytoskeleton in esophageal squamous cell carcinoma (ESCC) cells, however, the underlying molecular mechanisms were not identified. Here, using interactome analysis, we identified ezrin (EZR), fascin (FSCN1), heat shock protein beta-1 (HSPB1), and tropomodulin-3 (TMOD3) as actin-binding proteins that associate with cytoplasmic LOXL2, as well as with its L2Δ13 variant. High levels of LOXL2 and L2Δ13 and their cytoskeletal partners correlated with poor clinical outcome in patients with ESCC. To better understand the significance of these interactions, we focused on the interaction of LOXL2 with ezrin. Phosphorylation of ezrin at T567 was greatly reduced following depletion of LOXL2 and was enhanced following LOXL2/L2Δ13 reexpression. Furthermore, LOXL2 depletion inhibited the ability of ezrin to promote tumor progression. These results suggest that LOXL2-induced ezrin phosphorylation, which also requires PKCα, is critical for LOXL2-induced cytoskeletal reorganization that subsequently promotes tumor cell invasion and metastasis in ESCC. In summary, we have characterized a novel molecular mechanism that mediates, in part, the protumorigenic activity of LOXL2. These findings may enable the future development of therapeutic agents targeting cytoplasmic LOXL2. SIGNIFICANCE: LOXL2 and its spliced isoform L2Δ13 promote cytoskeletal reorganization and invasion of esophageal cancer cells by interacting with cytoplasmic actin-binding proteins such as ezrin.
LOXL2 (lysyl oxidase-like 2), an enzyme that catalyzes oxidative deamination of lysine residue, is upregulated in esophageal squamous cell carcinoma (ESCC). A LOXL2 splice variant LOXL2-e13 and its ...wild type were overexpressed in ESCC cells followed by microarray analyses. In this study, we explored the potential role and molecular mechanism of LOXL2-e13 based on known protein-protein interactions (PPIs), following microarray analysis of KYSE150 ESCC cells overexpressing a LOXL2 splice variant, denoted by LOXL2-e13, or its wild-type counterpart. The differentially expressed genes (DEGs) of LOXL2-WT and LOXL2-e13 were applied to generate individual PPI subnetworks in which hundreds of DEGs interacted with thousands of other proteins. These two DEG groups were annotated by Functional Annotation Chart analysis in the DAVID bioinformatics database and compared. These results found many specific annotations indicating the potential specific role or mechanism for LOXL2-e13. The DEGs of LOXL2-e13, comparing to its wild type, were prioritized by the Random Walk with Restart algorithm. Several tumor-related genes such as ERO1L, ITGA3, and MAPK8 were found closest to LOXL2-e13. These results provide helpful information for subsequent experimental identification of the specific biological roles and molecular mechanisms of LOXL2-e13. Our study also provides a work flow to identify potential roles of splice variants with large scale data.
Esophageal squamous cell carcinoma (ESCC) is a common malignant gastrointestinal tumor threatening global human health. For patients diagnosed with ESCC, determining the prognosis is a huge ...challenge. Due to their important role in tumor progression, long non-coding RNAs (lncRNAs) may be putative molecular candidates in the survival prediction of ESCC patients. Here, we obtained three datasets of ESCC lncRNA expression profiles (GSE53624, GSE53622, and GSE53625) from the Gene Expression Omnibus (GEO) database. The method of statistics and machine learning including survival analysis and LASSO regression analysis were applied. We identified a six-lncRNA signature composed of AL445524.1, AC109439.2, LINC01273, AC015922.3, LINC00547, and PSPC1-AS2. Kaplan-Meier and Cox analyses were conducted, and the prognostic ability and predictive independence of the lncRNA signature were found in three ESCC datasets. In the entire set, time-dependent ROC curve analysis showed that the prediction accuracy of the lncRNA signature was remarkably greater than that of TNM stage. ROC and stratified analysis indicated that the combination of six-lncRNA signature with the TNM stage has the highest accuracy in subgrouping ESCC patients. Furthermore, experiments subsequently confirmed that one of the lncRNAs LINC01273 may play an oncogenic role in ESCC. This study suggested the six-lncRNA signature could be a valuable survival predictor for patients with ESCC and have potential to be an auxiliary biomarker of TNM stage to subdivide ESCC patients more accurately, which has important clinical significance.
Integrins have been shown to play an important role in the tumorigenesis of many cancers. In this work, we aimed to explore the expression and clinical value of Integrin α5β1 in esophageal squamous ...cell carcinoma (ESCC), and the effect of integrin β1 on the development and chemo-resistance of ESCC cells.
The expression profiling of integrins was analyzed in the mRNA expression dataset of ESCC. The expression of Integrin α5β1 in 278 cases of ESCC tissues and 62 cases of paracancerous tissues was detected by immunohistochemistry (IHC). The association between the expression of Integrin α5β1 and the survival of ESCC patients was analyzed by Kaplan-Meier analysis. The effect of Integrin β1 on the proliferation, migration, and invasion of ESCC cells was examined by MTS, Transwell migration, and Transwell invasion assay. The effect of Integrin β1 and L1 cell adhesion molecule (L1CAM) on cisplatin resistance was detected by MTS and the signal pathways involved were analyzed by Western blotting.
Integrin β1 and Integrin α5 were significantly up-regulated in ESCC. High expression of Integrin β1 was also related to worse overall survival of ESCC patients and patients with low levels of both Integrin β1 and Integrin α5 showed the shortest survival. Results of IHC revealed that Integrin α5β1 was up-regulated in ESCC and its high expression was associated with poor prognosis and could serve as an independent prognostic factor. siRNA-mediated Integrin β1 silencing or antibody blocking restrained the proliferation, migration, and invasion of ESCC cells. Simultaneous knockdown of Integrin β1 and L1CAM reduced the cisplatin resistance of ESCC cells. Further studies showed that knockdown of Integrin β1 and L1CAM suppressed the activity of Akt signaling with or without cisplatin treatment. Moreover, dual high expression of Integrin β1 and L1CAM was related to worse overall survival of ESCC patients treated with preoperative chemotherapy.
Integrin α5β1 was up-regulated in ESCC and could be used as a new prognostic indicator for ESCC patients. In addition, Integrin β1 was involved in the proliferation, invasion, and chemo-resistance of ESCC cells.
Conventionally, Rho guanine nucleotide exchange factors (GEFs) are known activators of Rho guanosine triphosphatases (GTPases) that promote tumorigenesis. However, the role of Rho GEFs in non-small ...cell lung cancer (NSCLC) remains largely unknown. Through the screening of 81 Rho GEFs for their expression profiles and correlations with survival, four of them were identified with strong significance for predicting the prognosis of NSCLC patients. The four Rho GEFs, namely ABR, PREX1, DOCK2 and DOCK4, were downregulated in NSCLC tissues compared to normal tissues. The downregulation of ABR, PREX1, DOCK2 and DOCK4, which can be attributfed to promoter methylation, is correlated with poor prognosis. The underexpression of the four key Rho GEFs might be related to the upregulation of MYC signaling and DNA repair pathways, leading to carcinogenesis and poor prognosis. Moreover, overexpression of ABR was shown to have a tumor-suppressive effect in PC9 and H1703 cells. In conclusion, the data reveal the unprecedented role of ABR as tumor suppressor in NSCLC. The previously unnoticed functions of Rho GEFs in NSCLC will inspire researchers to investigate the distinct roles of Rho GEFs in cancers, in order to provide critical strategies in clinical practice.
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