Zinc finger E-box binding (ZEB) proteins ZEB1 and ZEB2 are transcription factors essential in transforming growth factor (TGF)-β-mediated senescence, epithelial to mesenchymal transition (EMT) and cancer stem cell function. ZEBs are negatively regulated by members of the miR-200 microRNA family, but precisely how tumor cells expressing ZEBs emerge during invasive growth remains unknown. Here we report that NOTCH3-mediated signaling prevents expansion of a unique subset of ZEB-expressing cells. ZEB expression was associated with the lack of cellular capability of undergoing NOTCH3-mediated squamous differentiation in human esophageal cells. Genetic inhibition of the Notch-mediated transcriptional activity by dominant-negative Mastermind-like1 (DNMAML1) prevented squamous differentiation and induction of Notch target genes including NOTCH3. Moreover, DNMAML1 enriched EMT competent cells exhibited robust upregulation of ZEBs, downregulation of the miR-200 family, and enhanced anchorage independent growth and tumor formation in nude mice. RNA interference (RNAi) experiments suggested the involvement of ZEBs in anchorage independent colony formation, invasion and TGF-β-mediated EMT. Invasive growth and impaired squamous differentiation was recapitulated upon Notch inhibition by DNMAML1 in organotypic 3D culture, a form of human tissue engineering. Together, our findings indicate that NOTCH3 is a key factor limiting the expansion of ZEB-expressing cells, providing novel mechanistic insights into the role of Notch signaling in the cell fate regulation and disease progression of squamous esophageal cancers.
Notch; EMT; squamous cell differentiation; ZEB1; miR-200
Background & Aims
The Notch receptor family regulates cell fate through cell-cell communication. CSL (CBF-1/RBP-jκ, Su(H), Lag-1) drives canonical Notch-mediated gene transcription during cell lineage specification, differentiation and proliferation in the hematopoietic system, the intestine, the pancreas and the skin. However, the functional roles of Notch in esophageal squamous epithelial biology remain unknown.
Normal esophageal keratinocytes were stimulated with calcium chloride to induce terminal differentiation. The squamous epithelia were reconstituted in organotypic three-dimensional culture, a form of human tissue engineering. Notch was inhibited in culture with a γ-secretase inhibitor or dominant negative mastermind-like1 (DNMAML1). The roles of Notch receptors were evaluated by in vitro gain-of-function and loss-of-function experiments. Additionally, DNMAML1 was targeted to the mouse esophagus by cytokeratin K14 promoter-driven Cre (K14Cre) recombination of Lox-STOP-Lox-DNMAML1. Notch-regulated gene expression was determined by reporter transfection, chromatin immunoprecipitation (ChIP) assays, quantitative reverse-transcription polymerase chain reactions (RT-PCR), Western blotting, immunofluorescence and immunohistochemistry.
NOTCH1 (N1) was activated at the onset of squamous differentiation in the esophagus. Intracellular domain of N1 (ICN1) directly activated NOTCH3 (N3) transcription, inducing HES5 and early differentiation markers such as involucrin (IVL) and cytokeratin CK13 in a CSL-dependent fashion. N3 enhanced ICN1 activity and was required for squamous differentiation. Loss of Notch signaling in K14Cre;DNMAML1 mice perturbed esophageal squamous differentiation and resulted in N3 loss and basal cell hyperplasia.
Notch signaling is important for esophageal epithelial homeostasis. In particular, the crosstalk of N3 with N1 during differentiation provides novel, mechanistic insights into Notch signaling and squamous epithelial biology.
NOTCH1; NOTCH3; esophageal epithelium; squamous differentiation
Background and Objective
Despite great progress in treatment, the prognosis for patients with esophageal squamous cell carcinoma (ESCC) remains poor, highlighting the importance of early detection. Although upper endoscopy can be used for the screening of esophagus, it has limited sensitivity for early stage disease. Thus, development of new diagnosis approach to improve diagnostic capabilities for early detection of ESCC is an important need. The aim of this study was to assess the feasibility of using cathepsin B (CB) as a novel imaging target for the detection of human ESCC by near-infrared optical imaging in nude mice.
Initially, we examined specimens from normal human esophageal tissue, intraepithelial neoplasia lesions, tumor in situ, ESCC and two cell lines including one human ESCC cell line (Eca-109) and one normal human esophageal epithelial cell line (HET-1A) for CB expression by immunohistochemistry and western blot, respectively. Next, the ability of a novel CB activatable near-infrared fluorescence (NIRF) probe detecting CB activity presented in Eca-109 cells was confirmed by immunocytochemistry. We also performed in vivo imaging of tumor bearing mice injected with the CB probe and ex vivo imaging of resected tumor xenografts and visceral organs using a living imaging system. Finally, the sources of fluorescence signals in tumor tissue and CB expression in visceral organs were identified by histology.
CB was absent in normal human esophageal mucosa, but it was overexpressed in ESCC and its precursor lesions. The novel probe for CB activity specifically detected ESCC xenografts in vivo and in vitro.
CB was highly upregulated in human ESCC and its precursor lesions. The elevated CB expression in ESCC allowed in vivo and in vitro detection of ESCC xenografts in nude mice. Our results support the usefulness of CB activity as a potential imaging target for the detection of human ESCC.
Human squamous cell cancers are the most common epithelially derived malignancies. One example is esophageal squamous cell carcinoma (ESCC), which is associated with a high mortality rate (1) that is related to a propensity for invasion and metastasis (2). Here we report that periostin, a highly expressed cell adhesion molecule, is a key component of a novel tumor invasive signature obtained from an organotypic culture model of engineered ESCC. This tumor invasive signature classifies with human ESCC microarrays, underscoring its utility in human cancer. Genetic modulation of periostin promotes tumor cell migration and invasion as revealed in gain of and loss of function experiments. Inhibition of EGFR signaling and restoration of wild-type p53 function were each found to attenuate periostin, suggesting interdependence of two common genetic alterations with periostin function. Collectively, our studies reveal periostin as an important mediator of ESCC tumor invasion and they indicate that organotypic (3D) culture can offer an important tool to discover novel biologic effectors in cancer.
tumor microenvironment; periostin; EGFR; p53
Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive forms of human cancer with poor prognosis due to late diagnosis and metastasis. Common genomic alterations in ESCC include p53 mutation, p120ctn inactivation, and overexpression of oncogenes such as cyclin D1, EGFR, and c-Met. Using esophageal epithelial cells transformed by the overexpression of EGFR and p53R175H, we find novel evidence of a functional link between p53R175H and the c-Met receptor tyrosine kinase to mediate tumor cell invasion. Increased c-Met receptor activation was observed upon p53R175H expression and enhanced further upon subsequent EGFR overexpression. We inhibited c-Met phosphorylation, resulting in diminished invasion of the genetically transformed primary esophageal epithelial cells (EPC-hTERT-EGFR-p53R175H), suggesting that the mechanism of increased invasiveness upon EGFR and p53R175H expression may be the result of increased c-Met activation. These results suggest that the use of therapeutics directed at c-Met in ESCC and other squamous cell cancers.
p53 mutation; c-Met; esophageal cancer; tumor invasion
Genetic inactivation of Notch signaling in CD4−CD8− double-negative (DN) thymocytes was previously shown to impair T cell receptor (TCR) gene rearrangement and to cause a partial block in CD4+CD8+ double-positive (DP) thymocyte development in mice. In contrast, in vitro cultures suggested that Notch was absolutely required for the generation of DP thymocytes independent of pre-TCR expression and activity. To resolve the respective role of Notch and the pre-TCR, we inhibited Notch-mediated transcriptional activation in vivo with a green fluorescent protein–tagged dominant-negative Mastermind-like 1 (DNMAML) that allowed us to track single cells incapable of Notch signaling. DNMAML expression in DN cells led to decreased production of DP thymocytes but only to a modest decrease in intracellular TCRβ expression. DNMAML attenuated the pre-TCR–associated increase in cell size and CD27 expression. TCRβ or TCRαβ transgenes failed to rescue DNMAML-related defects. Intrathymic injections of DNMAML− or DNMAML+ DN thymocytes revealed a complete DN/DP transition block, with production of DNMAML+ DP thymocytes only from cells undergoing late Notch inactivation. These findings indicate that the Notch requirement during the β-selection checkpoint in vivo is absolute and independent of the pre-TCR, and it depends on transcriptional activation by Notch via the CSL/RBP-J–MAML complex.
Esophageal squamous cell carcinoma (ESCC) is often diagnosed at later stages until they are incurable. MicroRNA (miR) is a small, non-coding RNA that negatively regulates gene expression mainly via translational repression. Accumulating evidence indicates that deregulation of miR is associated with human malignancies including ESCC. The aim of this study was to identify miR that could be specifically expressed and exert distinct biological actions in ESCC.
Total RNA was extracted from ESCC cell lines, OE21 and TE10, and a non-malignant human esophageal squamous cell line, Het-1A, and subjected to microarray analysis. Expression levels of miR that showed significant differences between the 2 ESCC and Het-1A cells based on the comprehensive analysis were analyzed by the quantitative reverse transcriptase (RT)-PCR method. Then, functional analyses, including cellular proliferation, apoptosis and Matrigel invasion and the wound healing assay, for the specific miR were conducted. Using ESCC tumor samples and paired surrounding non-cancerous tissue obtained endoscopically, the association with histopathological differentiation was examined with quantitative RT-PCR.
Based on the miR microarray analysis, there were 14 miRs that showed significant differences (more than 2-fold) in expression between the 2 ESCC cells and non-malignant Het-1A. Among the significantly altered miRs, miR-205 expression levels were exclusively higher in 5 ESCC cell lines examined than any other types of malignant cell lines and Het-1A. Thus, miR-205 could be a specific miR in ESCC. Modulation of miR-205 expression by transfection with its precursor or anti-miR-205 inhibitor did not affect ESCC cell proliferation and apoptosis, but miR-205 was found to be involved in cell invasion and migration. Western blot revealed that knockdown of miR-205 expression in ESCC cells substantially enhanced expression of zinc finger E-box binding homeobox 2, accompanied by reduction of E-cadherin, a regulator of epithelial mesenchymal transition. The miR-205 expression levels were not associated with histological differentiation of human ESCC.
These results imply that miR-205 is an ESCC-specific miR that exerts tumor-suppressive activities with EMT inhibition by targeting ZEB2.
Tumor suppressor maspin is a differentially regulated gene in the progression of many types of cancer. While the biological function of maspin in blocking tumor invasion and metastasis is consistent with the loss of maspin expression at the late stage of tumor progression, the differential expression and the biological significance of maspin in early stage of tumor progression appear to be complex and remain to be elucidated. In the current study, we examined the expression of maspin in 84 esophageal squamous cell carcinoma (ESCC) cases (stages I–III) and 55 non-tumor adjacent esophageal tissue specimens by immunohistochemical (IHC) staining. The correlation of maspin with clinicopathological parameters was analyzed. Compared to normal esophageal squamous tissue where 80% (47/55) of the cases expressed maspin at a low to moderate level, all ESCC specimens (100% (84/84)) were positive for maspin expression at a moderate to high level. ESCC with low or moderate maspin expression had significantly shorter postoperative survival rates compared to those that had high maspin expression (p<0.001). Since the correlation of maspin with ESCC histology and the correlation of maspin with ESCC prognosis seem to be at odds, we further investigated the biological function of maspin in ESCC using the established ESCC cell lines. The expression of maspin in five human esophageal squamous cancer cell lines (T12, E450, KYSE150, EC109, and KYSE510) was examined by the Western blot. ESCC cell line KYSE510 that did not express maspin and was stably transfected by maspin cDNA or an empty vector. The resulting transfected cells were characterized in vitro. Maspin expression significantly inhibited cell proliferation, motility and matrigel invasion. Taken together, our data suggest that the transient up-regulation of maspin in the early development of ESCC may be a defense mechanism against further transition towards more malignant phenotypes, ultimately slowing down ESCC tumor progression.
Extracellular signal-regulated kinases (ERKs) are activated by the MAPK pathway. ERKs are downstream effectors of the epidermal growth factor receptor (EGFR), which belongs to the receptor tyrosine kinases family. Studies on the activation of the EGFR-ERK pathway in Kazakh patients with esophageal squamous cell carcinoma (ESCC) have not been reported. Using immunohistochemical staining on tissue microarrays, we investigated the protein expression of EGFR and ERK in 90 ethnic Kazakh patients with ESCC and 48 adjacent normal esophageal tissues (NETs). EGFR and ERK1 expression was localized in the cytoplasm, whereas ERK2 expression was localized in the nucleus. Both were more highly expression in the ESCC tissues than in the NETs, and the difference was considered significant (P = 0.003, 0.002, and 0.005, respectively). ERK1 and EGFR expression was positively correlated with lymph nodes metastasis (P = 0.011 and 0.013, respectively). ERK1 staining was also significantly associated with tumor-node-metastases stage of ESCC (P = 0.044). ERK2 staining was significantly associated with Histological grade (P = 0.012). Furthermore, ERK1 and EGFR expression in the ESCC tissues were positively correlated (r = 0.413, P < 0.001); EGFR was more highly expressed in the ESCC tissues with high ERK1 expression than in the ESCC tissues with low ERK1 expression (4.95 ± 0.57 vs. 3.21 ± 0.35, P = 0.01). This study is thus far the first to demonstrate the correlation between EGFR overexpression and ERK overexpression in Kazakh patients with ESCC. This correlation suggests that the EGFR-ERK signaling pathway participates in ESCC progression and can thus be used as a prognostic marker.
Esophageal squamous cell carcinoma; Kazakh; epidermal growth factor receptor; extracellular signal-regulated kinase
This study identified significantly down-regulated microRNAs (miRs) specific for esophageal squamous cell carcinoma (ESCC) cells. Total RNA was extracted from ESCC cell lines (OE21 and TE10) and a non-malignant human esophageal squamous cell line (Het1A), and subjected to microarray analysis. Expression levels of miRs that showed significant down-regulation in ESCC cells compared to Het1A cells based on the comprehensive analysis were analyzed by quantitative reverse transcription polymerase chain reaction. Among the significantly down-regulated miRs, miR-10a expression levels in the five ESCC cell lines examined were significantly lower than in Het1A and the esophageal adenocarcinoma cells. Since miR-10a is a specific miR in ESCC, its clinical relevance was examined. Using ESCC tumor samples and non-cancerous tissue obtained endoscopically, the involvement of miR-10a in the clinicopathological findings was examined. MiR-10a expression was comparably down-regulated in the tumors of high-grade intraepithelial neoplasm and non-invasive ESCC, while the expression levels were elevated in the invasive ESCC tumors. Treatment with a demethylating agent, 5-aza-2′-deoxycytidine, restored miR-10a expression in OE21 cells. Only a modest additive or synergistic effect was observed in the presence of a histone deacetylase inhibitor, trichostatin A. These results imply that miR-10a may be differentially expressed in ESCC cells and may be involved in ESCC development and progression. The unique epigenetic regulation of miR-10a expression can be mediated via hypermethylation of the CpG islands proximal to its gene locus, at least in certain ESCC cells.
microRNA; microRNA 10a; esophageal squamous cell carcinoma; DNA methylation
Lymph node involvement and tumor-induced lymphangiogenesis appear as the earliest features of esophageal squamous cell carcinoma (ESCC), although the molecular regulatory mechanisms involved have remained unclear. Our aim was to investigate the contribution of NF-κB and Notch1 signaling to lymph node involvement and tumor-induced lymphangiogenesis in ESCC.
Material and methods
NF-κB and Notch1 expression in 60 tissue samples of ESCC were assessed by immunohistochemical staining. The correlations of NF-κB and Notch1 with lymph node involvement, lymphatic vessel density (LVD), podoplanin, and vascular endothelial growth factor-C (VEGF-C) were further evaluated to determine the association of NF-κB and Notch1 expression with tumor-induced lymphangiogenesis.
Chi-square tests revealed that NF-κB and Notch1 expression in ESCC tissues were significant associated with lymph node metastasis, LVD, podoplanin, and VEGF-C expression. Strong expression of NF-κB, but weak expression of Notch1, was observed in tumor tissues with lymph nodes involvement (P < 0.05 for both). The mean histoscores of LVD, podoplanin, and VEGF-C staining were higher in high-NF-κB-expressing tissue than in low-expressing tissue (P < 0.05 for each). In contrast, the mean histoscores of LVD and VEGF-C staining were lower in high-Notch1-expressing tissue than in low-expressing tissue (P < 0.05 for both). A multiple factors analysis of LVD and VEGF-C further demonstrated that LVD and VEGF-C status were significantly correlated with NF-κB and Notch1 expression in tumors. NF-κB and Notch1 expression were also significantly inversely correlated (P < 0.05).
These results suggest that different patterns of NF-κB and Notch1 signaling contribute to lymph nodes metastasis and tumor-induced lymphangiogenesis of ESCC, and reveal that up-regulation of NF-κB is associated with down-regulation of Notch1 in tumor tissue.
esophageal squamous cell carcinoma; Notch; NF-κB; angiogenesis; lymphangiogenesis
Epidermal growth factor receptor (EGFR) is frequently overexpressed in esophageal carcinoma and its precursor lesions. To gain insights into how EGFR overexpression affects cellular functions in primary human esophageal cells, we performed gene expression profiling and identified insulin-like growth factor-binding protein (IGFBP)-3 as the most up-regulated gene. IGFBP-3 regulates cell proliferation through both insulin-like growth factor-dependent and independent mechanisms. We found that IGFBP-3 mRNA and protein expression was increased in EGFR-overexpressing primary and immortalized human esophageal cells. IGFBP-3 was also up-regulated in EGFR-overexpressing cells in organotypic culture and in EGFR transgenic mice. Furthermore, IGFBP-3 mRNA was overexpressed in 80% of primary esophageal squamous cell carcinomas and 60% of primary esophageal adenocarcinomas. Concomitant up-regulation of EGFR and IGFBP-3 was observed in 60% of primary esophageal squamous cell carcinomas. Immunohistochemistry revealed cytoplasmic localization of IGFBP-3 in the preponderance of preneoplastic and neoplastic esophageal lesions. IGFBP-3 was also overexpressed in esophageal cancer cell lines at both mRNA (60%) and protein (40%) levels. IGFBP-3 secreted by cancer cells was capable of binding to insulin-like growth factor I. Functionally, epidermal growth factor appeared to regulate IGFBP-3 expression in esophageal cancer cell lines. Finally, suppression of IGFBP-3 by small interfering RNA augmented cell proliferation, suggesting that IGFBP-3 may inhibit tumor cell proliferation as a negative feedback mechanism. In aggregate, we have identified for the first time that IGFBP-3 is an aberrantly regulated gene through the EGFR signaling pathway and it may modulate EGFR effects during carcinogenesis.
Esophageal quamous cell carcinoma (ESCC) is the predominant histological type of esophageal carcinoma in Asian populations. To date, few biomarkers have been identified for ESCC. In present study, we found a tumor suppressor, NUMB isoform 1 (NUMB-1), as a promising prognostic biomarker for patients with ESCC. NUMB-1 mRNA was downregulated in 66.7% of primary ESCC tissues when compared with matched adjacent non-tumor tissues. The low expression of NUMB-1 was significantly associated with high tumor recurrence (p=0.029) and poor post-operative overall survival (p=0.016). To further explore the underlying mechanisms by which NUMB-1 regulates ESCC, we demonstrated that ectopic expression of NUMB-1 inhibited cell proliferation through inducing G2/M phase arrest, which was accompanied by an increase in p21 and cyclin B1-cdc2 levels. However, it had no impact on apoptosis of ESCC cells. In addition, overexpression of NUMB-1 prevented epithelial-mesenchymal transition, inhibited invasion of ESCC cells and NOTCH pathway, suppressed Aurora-A activity by preventing phosphorylation of Aurora-A at T288 which resulted in cell cycle arrest. Taken together, our findings suggested NUMB-1 functions as a tumor-suppressor and serves as a prognositc biomarker for ESCC patients; thus, NUMB-1 may be a potential novel therapeutic target for treatment of ESCC.
esophageal squamous cell carcinoma; ESCC; NUMB isoform 1; Aurora-A; G2/M arrest
Systemic inhibition of Notch signaling was previously shown to attenuate experimental autoimmune encephalomyelitis (EAE), a disease model of multiple sclerosis in mice. Different studies attributed these effects to decreased T-bet and IFNγ expression, enhanced regulatory T cell function, reduced T cell chemotaxis to the central nervous system (CNS) or impaired Th9 cell differentiation. Interpretation of these heterogeneous findings is difficult, since past experimental strategies did not ensure complete Notch inhibition in T cells and since many cell populations could be affected by systemic Notch blockade. To resolve the role of Notch in T cells during EAE, we used the pan-Notch inhibitor dominant negative form of Mastermind-like 1 (DNMAML), as well as several complementary loss-of-function approaches specifically in myelin-reactive T cells. Notch inhibition in T cells profoundly decreased EAE incidence and severity. Notch-deprived myelin-reactive T cells had preserved activation and effector differentiation in secondary lymphoid tissues. However, Notch-deprived T cells failed to accumulate in the CNS post-immunization. Parking wild type and DNMAML T cells together in bone marrow chimeras increased accumulation of Notch-deprived T cells in the CNS post-immunization but did not prevent EAE, indicating the absence of dominant suppression by DNMAML T cells. Analysis of CNS-infiltrating DNMAML T cells revealed markedly defective IL-17A and IFNγ production, despite preserved T-bet expression. Altogether, our findings capture the profound overall effects of Notch signaling in myelin-reactive T cells and demonstrate that Notch controls the accumulation and pathogenic functions of CD4+ T cells within their target organ but not in lymphoid tissues during EAE.
HOX transcript antisense RNA (HOTAIR), which is expressed from the homebox C gene (HOXC) locus, is capable of reprogramming chromatin organisation and promoting cancer cell metastasis and can simultaneously bind the polycomb repressive complex 2, which enhances H3K27 trimethylation, and the LSD1-CoREST-REST complex, which is critical for H3K4 demethylation. Clinically, the overexpression of HOTAIR is a powerful predictor of the tumour progression and overall survival in patients with diverse cancers. The relationship between HOTAIR and oesophageal squamous cell carcinoma (ESCC), however, remains unclear. We investigated the role of HOTAIR in the pathogenesis of ESCC.
We used quantitative real-time PCR to determine the level of HOTAIR in ESCC cell lines and 100 ESCC samples from patients; 56 adjacent non-neoplastic tissues were used as controls. We measured the effect of HOTAIR knockdown and overexpression in ESCC cell lines using colony formation assays, anchorage-independent growth assays, the CCK-8 assay, transwell migration and invasion assays, and Annexin V-binding assays. We analysed the growth of ESCC xenograft tumours in nude mice. Changes in the gene expression and methylation levels in ESCC cell lines were analysed using gene expression microarrays and the Infinium HumanMethylation450K BeadChip assay, respectively.
The levels of HOTAIR were increased in ESCC cell lines and patient samples compared with the controls; the expression levels correlated with the disease stage and survival time. The knockdown of HOTAIR in the KYSE510 and KYSE180 ESCC cell lines using small hairpin RNAs (shRNAs) reduced the ability of the cells to form foci, migrate, and invade the extracellular matrix in culture, altered cell cycle progression, and increased the sensitivity of the cells to apoptosis. The HOTAIR knockdown reduced cancer cell metastasis in vivo, and the tumours formed by HOTAIR-silenced ESCC cells were smaller, both in size and weight, than the tumours and metastases formed by the shRNA vector control cells in a mouse xenograft model. The results of the gene microarray study showed that HOTAIR reprogrammed the gene expression profile of ESCC cells, and the gene ontology analysis revealed an enrichment in genes that are important for tumorigenesis, such as genes involved in cell migration and the regulation of the cell cycle. Comparing the gene expression profiles and DNA methylation analysis between the KYSE180 and KYSE180_HOTAIR cells revealed that only a small proportion of the methylation changes were correlated with gene expression changes.
HOX transcript antisense RNA is upregulated in ESCC cell lines and patient samples, and promotes ESCC cell proliferation and tumour metastasis in mice. The knockdown of HOTAIR resulted in significant changes in gene expression, and data analysis suggested that HOTAIR-mediated gene regulation has a critical role in ESCC progression and is a novel epigenetic molecular target for treating ESCC patients.
long non-coding RNAs; HOTAIR; epigenetic; oesophageal squamous cell carcinoma; metastasis; prognosis
Esophageal squamous cell carcinoma (ESCC) is a world-wide prevalent cancer, which is particularly common in certain regions of Asia. Here we report the whole-exome or targeted deep sequencing of 139 paired ESCC cases, and analysis of somatic copy number variations (SCNV) of over 180 ESCCs. We identified novel significantly mutated genes such as FAT1, FAT2, ZNF750 and KMT2D, in addition to previously discovered ones (TP53, PIK3CA and NOTCH1). Further SCNV evaluation, immunohistochemistry and biological analysis suggested their functional relevance in ESCC. Notably, RTK-MAPK-PI3K pathways, cell cycle and epigenetic regulation are frequently dysregulated by multiple molecular mechanisms in this cancer. Moreover, our approaches uncovered many novel druggable candidates, and XPO1 was further explored as a therapeutic target because of its mutation and protein overexpression. Together, our integrated study unmasks a number of novel genetic lesions in ESCC and provides an important molecular foundation for understanding esophageal tumors and developing therapeutic targets.
The Notch signaling pathway is a critical embryonic developmental regulatory pathway that has been implicated in oncogenesis. In non-small cell lung cancer (NSCLC), recent evidence suggests that Notch signaling may contribute to maintenance of a cancer stem or progenitor cell compartment required for tumorigenesis. We explored whether intact Notch signaling is required for NSCLC clonogenic and tumorigenic potential in vitro and in vivo using a series of genetically modified model systems. In keeping with previous observations, we find that Notch3 in particular is upregulated in human lung cancer lines, and that down regulation of Notch signaling using a selective γ-secretase inhibitor (MRK-003) is associated with decreased proliferation and clonogenic capacity in vitro. We demonstrate that this phenotype is rescued with the expression of NICD3, a constitutively active cleaved form of Notch3 not affected by γ-secretase inhibition. Using an inducible LSL-KRASG12D model of lung cancer in vivo, we demonstrate a transient upregulation of Notch pathway activity in early tumor precursor lesions. However, a more rigorous test of the requirement for Notch signaling in lung oncogenesis, crossing the LSL-KRASG12D mouse model with a transgenic with a similarly inducible global dominant negative suppressor of Notch activity, LSL-DNMAML (dominant negative mastermind-like), reveals no evidence of Notch pathway requirement for lung tumor initiation or growth in vivo. Distinct Notch family members may have different, and potentially opposing, activities in oncogenesis, and targeted inhibition of individual Notch family members may be a more effective anti-cancer strategy than global pathway suppression.
Hsp90α (heat shock protein 90α), one of the important molecular chaperones in cancer cell signal transduction, has been a new candidate target for cancer therapy. Cyclin B1, the client protein of Hsp90α, plays a key role as a mitotic cyclin in the G2-M phase transition during the cell cycle progression. However, the relationship between the level of HSP90α and cyclin B1, the location of Hsp90α and cyclin B1 in prognosis of esophageal squamous cell carcinoma (ESCC) has not been examined. Here, we demonstrate that the diagnostic significance of Hsp90α and cyclin B1 by immunohistochemistry and the association of Hsp90α and cyclin B1 expression in ESCC. In the specimens from 105 ESCC patients (81 stained with Hsp90α antibody by Immunohistochemistry, 65 with cyclin B1 antibody, and among them, 41 paired specimens were stained with Hsp90α and cyclin B1 respectively, and then checked for the correlation of the level and location of Hsp90α and cylcin B1. The positivity rate of Hsp90α and cyclin B1 expression were 96.3% (78 of 81) and 84.6% (55 of 65) respectively. Both of them, the expression levels are associated with the clinical pathological stage (Hsp90α, p=0.027; cyclin B1, p=0.007). No association was found between Hsp90α or cyclin B1 and gender, age, tumor location. As to TMN stage, there is no association with the level of Hsp90α, However, cyclin B1 expression is significantly related to tumor status (p=0.002). Interestingly, Hsp90α expression was negatively correlated to cyclin B1 expression (Gamma=-0.692, p=0.007) in the keratin pearls though there is a positive correlation in the other areas of tumor (Gamma=0.503, p=0.015), which suggest Hsp90α might play diverse roles in the cyclin B1 expression and cyclin B1 related cell cycle regulation in the different area of tumor. These findings demonstrated that the expression of Hsp90α, cyclin B1 protein is associated with tumor malignancy and prognosis for patients with human esophageal squamous cell carcinoma, and Hsp90α might be involved in cyclin B1 expression regulation and cell cycle regulation in keratin peal formation of ESCC.
Hsp90α; cyclin B1; esophageal squamous cell carcinoma; keratin pearl; prognosis; immunohistochemistry
Esophageal cancer is one of the most common cancers, and the 5-year survival rate is less than 10% due to lack of effective therapeutic agents. This study was to evaluate antitumor activity of Ec-LDP-Hr-AE, a recently developed bispecific enediyne-energized fusion protein targeting both epidermal growth factor receptor (EGFR) and epidermal growth factor receptor 2 (HER2), on esophageal cancer. The fusion protein Ec-LDP-Hr-AE consists of two oligopeptide ligands and an enediyne antibiotic lidamycin (LDM) for receptor binding and cell killing, respectively. The current study demonstrated that Ec-LDP-Hr had high affinity to bind to esophageal squamous cell carcinoma (ESCC) cells, and enediyne-energized fusion protein Ec-LDP-Hr-AE showed potent cytotoxicity to ESCC cells with differential expression of EGFR and HER2. Ec-LDP-Hr-AE could cause significant G2-M arrest in EC9706 and KYSE150 cells, and it also induced apoptosis in ESCC cells in a dosage-dependent manner. Western blot assays showed that Ec-LDP-Hr-AE promoted caspase-3 and caspase-7 activities as well as PARP cleavage. Moreover, Ec-LDP-Hr-AE inhibited cell proliferation via decreasing phosphorylation of EGFR and HER2, and further exerted inhibition of the activation of their downstream signaling molecules. In vivo, at a tolerated dose, Ec-LDP-Hr-AE inhibited tumor growth by 88% when it was administered to nude mice bearing human ESCC cell KYSE150 xenografts. These results indicated that Ec-LDP-Hr-AE exhibited potent anti-caner efficacy on ESCC, suggesting it could be a promising candidate for targeted therapy of esophageal cancer.
Esophageal squamous cell carcinoma (ESCC) is one of the most common cancers in China. The lower survival rate of ESCC is attributed to late diagnosis and poor therapeutic efficacy; therefore, the identification of tumor-associated proteins as biomarkers for early diagnosis, and the discovery of novel targets for therapeutic intervention, seems very important for increasing the survival rate of ESCC. To identify tumor-associated proteins as biomarkers in ESCC, we have analyzed ESCC tissues and adjacent normal tissues by two-dimensional electrophoresis (2DE) and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) analysis. The results showed that a total of 104 protein spots with different expression levels were found on 2DE, and 47 proteins were eventually identified by MALDI-TOF MS. Among these identified proteins, 33 proteins including keratin 17 (KRT17), biliverdin reductase B (BLVRB), proteasome activatorsubunit 1 (PSME1), manganese superoxide dismutase (MnSOD), high-mobility group box-1(HMGB1), heat shock protein 70 (HSP70), peroxiredoxin (PRDX1), keratin 13 (KRT13), and so on were overexpressed, and 14 proteins including cystatin B (CSTB), tropomyosin 2 (TPM2), annexin 1 (ANX1), transgelin (TAGLN), keratin 19 (KRT19), stratifin (SFN), and so on were down-expressed in ESCC. Biological functions of these proteins are associated with cell proliferation, cell motility, protein folding, oxidative stress, and signal transduction. In the subsequent study using immunoassay on ESCC serum samples and tissue-array slides, two representative proteins, HSP70 and HMGB1, were selected as examples for the purpose of validation. The results showed that both HSP70 and HMGB1 can induce autoantibody response in ESCC sera and have higher expression in ESCC tissues. Especially, the frequency of antibodies to HSP70 in ESCC sera was significantly higher than that in normal human sera. The preliminary results suggest that some of these identified proteins might contribute to esophageal cell differentiation and carcinogenesis, certain proteins could be used as tumor-associated antigen (TAA) biomarkers in cancer diagnosis, and further studies on these identified proteins should provide more evidence of how these proteins are involved in carcinogenesis of ESCC.
esophageal squamous cell carcinoma (ESCC); tumor-associated proteins; biomarkers; proteomic approach; cancer autoantibody; cancer diagnosis
Esophageal squamous cell carcinoma (ESCC) is a highly aggressive malignancy, requiring effective biomarkers for prognosis and therapeutic responsiveness. Histone H3K9 methyltransferases (EHMT1 and EHMT2) are global genome organizers, which are crucial for maintaining the balance state of cells in a tissue-specific manner. It was previously suggested that EHMT1 expression is a predictor of prognosis in several malignant tumors; however, the prognostic significance of EHMT1 expression in ESCC has not been determined. A cohort of 50 ESCC cases and 46 paired normal esophageal tissue samples were evaluated to assess the levels of EHMT1 expression by immunohistochemistry and reverse transcription-polymerase chain reaction. The SPSS software package was used for statistical data analysis. A significantly upregulated EHMT1 expression was observed in squamous preinvasive lesions and ESCC compared to the matched normal esophageal epithelia (52.0 vs. 21.7%, respectively). The expression of EHMT1 was correlated with tumor grade (G), depth of invasion (T) and lymph node metastasis (N) in ESCC. EHMT1 overexpression was found to be associated with poor cancer-specific survival in squamous cell carcinomas (χ2=3.922, P=0.048). The expression of EHMT1 was identified as an independent prognostic factor for overall survival in ESCC patients. In conclusion, EHMT1 expression is upregulated in ESCC and early preinvasive esophageal squamous lesions and the overexpression of EHMT1 is associated with poor prognosis in ESCC. Therefore, the expression of EHMT1 may be an effective prognostic biomarker for ESCC.
histone methyltransferase; EHMT1; esophageal squamous cell cancer; prognosis
MicroRNA (miR)-29a has been associated with carcinogenesis in humans; however, its functional significance in esophageal squamous cell carcinoma (ESCC) is yet to be determined. In the present study, the expression of miR-29a was markedly downregulated in ESCC tissue and the ESCC TE-1 cell line, compared with normal esophageal tissue and cells. Furthermore, the present study identified that the forced expression of miR-29a in TE-1 cells significantly reduced cell proliferation and migration. miR-29a overexpression did not affect the expression of Notch1, however, it did increase the gene expression levels of hairy and enhancer of split 1 (Hes1), which is the key effector of the Notch signaling pathway. Direct targeting by miR-29a resulted in the downregulation of nuclear factor 1 A (Nfia), which represses the transcriptional activity of the Hes1 promoter. Furthermore, knockdown of Nfia increased Hes1 expression and inhibited cell growth in TE-1 cells. These results indicate that a low level of miR-29a expression is involved in ESCC tumorigenesis, and exogenous expression of miR-29a may repress cancer cell growth by downregulating Nfia and activating the Notch signaling pathway.
microRNA; esophageal squamous cell carcinoma; notch; nuclear factor 1 A; cell growth
The epidermal growth factor receptor (EGFR) signaling pathway regulates cell proliferation, differentiation, and survival, and is frequently dysregulated in esophageal and gastric cancers. Few studies have comprehensively examined the association between germline genetic variants in the EGFR pathway and risk of esophageal and gastric cancers. Based on a genome-wide association study in a Han Chinese population, we examined 3443 SNPs in 127 genes in the EGFR pathway for 1942 esophageal squamous cell carcinomas (ESCCs), 1758 gastric cancers (GCs), and 2111 controls. SNP-level analyses were conducted using logistic regression models. We applied the resampling-based adaptive rank truncated product approach to determine the gene- and pathway-level associations. The EGFR pathway was significantly associated with GC risk (P = 2.16×10−3). Gene-level analyses found 10 genes to be associated with GC, including FYN, MAPK8, MAP2K4, GNAI3, MAP2K1, TLN1, PRLR, PLCG2, RPS6KB2, and PIK3R3 (P<0.05). For ESCC, we did not observe a significant pathway-level association (P = 0.72), but gene-level analyses suggested associations between GNAI3, CHRNE, PAK4, WASL, and ITCH, and ESCC (P<0.05). Our data suggest an association between specific genes in the EGFR signaling pathway and risk of GC and ESCC. Further studies are warranted to validate these associations and to investigate underlying mechanisms.
Notch signaling involves the processes that govern cell proliferation, cell fate decision, cell differentiation and stem cell maintenance. Due to its fundamental role in stem cells, it has been speculated during the recent years that Notch family may have critical functions in cancer stem cells or cancer cells with a stem cell phenotype, therefore playing an important role in the process of oncogenesis. In this study, expression of Notch family in KYSE70, KYSE140 and KYSE450 squamous esophageal cancer cell lines and virus transformed squamous esophageal epithelial cell line Het-1A was examined by quantitative RT-PCR. Compared to the Het-1A cells, higher levels of Nocth1 and Notch3 expression in the cancer cell lines were identified. Due to the finding that NOTCH3 mainly mediates squamous cell differentiation, NOTCH1 expression was further studied in these cell lines. By Western blot analyses, the KYSE70 cell line which derived from a poorly differentiated tumor highly expressed Notch1, and the Notch1 expression in this cell line was hypoxia inducible, while the KYSE450 cell line which derived from a well differentiated tumor was always negative for Notch1, even in hypoxia. Additional studies demonstrated that the KYSE70 cell line was more 5-FU resistant than the KYSE450 cell line and such 5-FU resistance is correlated to Notch1 expression verified by Notch1 knockdown experiments. In clinical samples, Notch1 protein expression was detected in the basal cells of human esophagus epithelia, and its expression in squamous cell carcinomas was significantly associated with higher pathological grade and shorter overall survival. We conclude that Notch1 expression is associated with cell aggressiveness and 5-FU drug resistance in human esophageal squamous cell carcinoma cell lines in vitro and is significantly associated with a poor survival in human esophageal squamous cell carcinomas.
Human pituitary tumor-transforming 1 (PTTG1)/securin is a putative oncoprotein that is overexpressed in various tumor types. However, the involvement of PTTG1 in gastrointestinal cancer development and progression remains unclear. In this study, we investigated the clinical significance and biological effects of PTTG1 in esophageal squamous cell carcinoma (ESCC). Immunohistochemical studies performed on 113 primary ESCC specimens revealed a high prevalence of PTTG1 overexpression (60.2%), which was significantly associated with lymph node metastasis (regional, P = 0.042; distant, P = 0.005), advanced tumor stage (P = 0.028), and poorer overall survival (P = 0.017, log-rank test; P = 0.044, Cox proportional hazard model). Eleven ESCC cell lines expressed PTTG1 protein at levels 2.4 to 6.6 times higher than those in normal esophageal epithelial cells (HEEpiC). PTTG1 protein expression was confined to the nucleus in HEEpiC cells but present in both the cytoplasm and nucleus in ESCC cells. Two small interfering RNAs (siRNA) inhibited PTTG1 mRNA and protein expression in three ESCC cell lines by 77% to 97%. In addition, PTTG1 down-regulation by these siRNAs significantly reduced cell motility in all three ESCC cell lines (P < 0.01) in vitro, as well as popliteal lymph node metastases of ESCC cells in nude mice (P = 0.020). Global gene expression profiling suggested that several members of the Ras and Rho gene families, including RRAS, RHOG, ARHGAP1, and ARHGADIA, represented potential downstream genes in the PTTG1 pathway. Taken together, these findings suggest that PTTG1 overexpression promotes cell motility and lymph node metastasis in ESCC patients, leading to poorer survival. Thus, PTTG1 constitutes a potential biomarker and therapeutic target in ESCCs with lymph node metastases.