SOX2 identified as a target gene for the amplification at 3q26 that is frequently detected in esophageal squamous cell carcinoma

GALNT6, GALNT14, and Gal-3 in association with GDF-15 promotes drug resistance and stemness of breast cancer via β-catenin axis

N-acetylgalactosaminyltransferases (GALNTs) are a polypeptide responsible for aberrant glycosylation in breast cancer (BC), but the mechanism is unclear. In this study, expression levels of GALNT6, GALNT14, and Gal-3 were assessed in BC, and their association with GDF-15, β-catenin, stemness (SOX2 and OCT4), and drug resistance marker (ABCC5) was evaluated. Gene expression of GALNT6, GALNT14, Gal-3, GDF-15, OCT4, SOX2, ABCC5, and β-catenin in tumor and adjacent non-tumor tissues (n = 30) was determined. The same was compared with GEO-microarray datasets. A significant increase in the expression of candidate genes was observed in BC tumor compared to adjacent non-tumor tissue; and in pre-therapeutic patients compared to post-therapeutic. GALNT6, GALNT14, Gal-3, and GDF-15 showed positive association with β-catenin, SOX2, OCT4, and ABCC5 and were significantly associated with poor Overall Survival. Our findings were also validated via in silico analysis. Our study suggests that GALNT6, GALNT14, and Gal-3 in association with GDF-15 promote stemness and intrinsic drug resistance in BC, possibly by β-catenin signaling pathway.

Sox2 and βIII-Tubulin as Biomarkers of Drug Resistance in Poorly Differentiated Sinonasal Carcinomas

Poorly differentiated sinonasal carcinomas (PDCs) are tumors that have a poor prognosis despite advances in classical treatment. Predictive and prognostic markers and new personalized treatments could improve the oncological outcomes of patients. In this study, we analyzed SOX2 and βIII-tubulin as biomarkers that could have prognostic and therapeutic impacts on these tumors. The cohort included 57 cases of PDCs: 36 sinonasal undifferentiated carcinoma (SNUC) cases, 13 olfactory neuroblastoma (ONB) cases, and 8 sinonasal neuroendocrine carcinoma (SNEC) cases. Clinical follow-up data were available for 26 of these cases. Sox2 expression was detected using immunohistochemistry in 6 (75%) SNEC cases, 19 (53%) SNUC cases, and 6 (46%) ONB cases. The absence of Sox2 staining correlated with a higher rate of recurrence (p = 0.015), especially distant recurrence. The majority of cases showed βIII-tubulin expression, with strong positivity in 85%, 75%, and 64% of SNEC, ONB, and SNUC cases, respectively. Tumors with stronger βIII-tubulin expression demonstrated longer disease-free survival than those with no expression or low expression (p = 0.049). Sox2 and βIII-tubulin expression is common in poorly differentiated sinonasal tumors and has prognostic and therapeutic utility.

Mammalian esophageal stratified tissue homeostasis is maintained distinctively by the epithelial pluripotent p63+Sox2+ and p63-Sox2+ cell populations

Self-renewing, damage-repair and differentiation of mammalian stratified squamous epithelia are subject to tissue homeostasis, but the regulation mechanisms remain elusive. Here, we investigate the esophageal squamous epithelial tissue homeostasis in vitro and in vivo. We establish a rat esophageal organoid (rEO) in vitro system and show that the landscapes of rEO formation, development and maturation trajectories can mimic those of rat esophageal epithelia in vivo. Single-cell RNA sequencing (scRNA-seq), snapshot immunostaining and functional analyses of stratified "matured" rEOs define that the epithelial pluripotent stem cell determinants, p63 and Sox2, play crucial but distinctive roles for regulating mammalian esophageal tissue homeostasis. We identify two cell populations, p63+Sox2+ and p63-Sox2+, of which the p63+Sox2+ population presented at the basal layer is the cells of origin required for esophageal epithelial stemness maintenance and proliferation, whereas the p63-Sox2+ population presented at the suprabasal layers is the cells of origin having a dual role for esophageal epithelial differentiation (differentiation-prone fate) and rapid tissue damage-repair responses (proliferation-prone fate). Given the fact that p63 and Sox2 are developmental lineage oncogenes and commonly overexpressed in ESCC tissues, p63-Sox2+ population could not be detected in organoids formed by esophageal squamous cell carcinoma (ESCC) cell lines. Taken together, these findings reveal that the tissue homeostasis is maintained distinctively by p63 and/or Sox2-dependent cell lineage populations required for the tissue renewing, damage-repair and protection of carcinogenesis in mammalian esophagi.

Control of SOX2 protein stability and tumorigenic activity by E3 ligase CHIP in esophageal cancer cells

SOX2 is highly expressed and controls tumor initiation and cancer stem cell function in various squamous cell carcinomas including esophageal squamous cancer. However, the molecular mechanism leading to SOX2 overexpression in cancer is incompletely understood. Here, we identified CHIP, a chaperone-associated ubiquitin E3 ligase, as a novel negative regulator of SOX2 protein stability and tumorigenic activity in esophageal squamous carcinoma cells. We showed that CHIP interacted with SOX2 primarily via chaperone HSP70, together they catalyzed SOX2 ubiquitination and degradation via proteasome. In contrast, HSP90 promoted SOX2 stability and inhibition of HSP90 activity induced SOX2 ubiquitination and degradation. Notably, unlike the case in normal esophageal tissues where CHIP was detected in both the cytoplasm and nucleus, CHIP in clinical esophageal tumor specimens was predominantly localized in the cytoplasm. Consistent with this observation, we observed increased expression of exportin-1/CRM-1 in clinical esophageal tumor specimens. We further demonstrated that CHIP catalyzed SOX2 ubiquitination and degradation primarily in the nuclear compartment. Taken together, our study has identified CHIP as a key suppressor of SOX2 protein stability and tumorigenic activity and revealed CHIP nuclear exclusion as a potential mechanism for aberrant SOX2 overexpression in esophageal cancer. Our study also suggests HSP90 inhibitors as potential therapeutic agents for SOX2-positive cancers.

The roles of the SOX2 protein in the development of esophagus and esophageal squamous cell carcinoma, and pharmacological target for therapy

SOX2 is a transcription factor belonging to the SOX gene family, whose activity has been associated with the maintenance of the stemness and self-renewal of embryonic stem cells (ESCs), as well as the induction of differentiated cells into induced pluripotent stem cells (iPSCs). Moreover, accumulating studies have shown that SOX2 is amplified in various cancers, notably in esophageal squamous cell carcinoma (ESCC). In addition, SOX2 expression is linked to multiple malignant processes, including proliferation, migration, invasion, and drug resistance. Taken together, targeting SOX2 might shed light on novel approaches for cancer therapy. In this review, we aim to summarize the current knowledge regarding SOX2 in the development of esophagus and ESCC. We also highlight several therapeutic strategies for targeting SOX2 in different cancer types, which can provide new tools to treat cancers possessing abnormal levels of SOX2 protein.

p21-activated kinase 2 binds to transcription factor SOX2 and up-regulates DEK to promote the progression of lung squamous cell carcinoma

Lung squamous cell carcinoma (LSCC) is a prevalent and progressive subtype of lung cancer. This study aimed to substantiate the regulatory effect of the PAK2/SOX2/DEK axis on the LSCC development. LSCC tissues (n = 83) and adjacent normal tissues were collected and SOX2 expression was determined by qRT-PCR and Western blotting. Correlation between SOX2 expression and the prognosis of LSCC patients was then explored utilizing Kaplan-Meier analysis. Co-immunoprecipitation and glutathione-S-transferase pull-down assays were conducted to validate the binding of SOX2 to DEK. Gain- and loss- of function assays were then performed on LSCC cells, with CCK-8 and Transwell assays applied to detect the malignant behaviors of cells. A mouse xenograft model of LSCC was further established for in vivo validation. The expression levels of SOX2, PAK2 and DEK were up-regulated in LSCC tissues and cells. SOX2 overexpression was correlated with poor prognosis of LSCC patients. Knockdown of SOX2 weakened the viability and the migratory and invasive potential of LSCC cells. Further, PAK2 directly interacted with SOX2. PAK2 overexpression accelerated the malignant phenotypes of LSCC cells through interplay with SOX2. Moreover, SOX2 activated the expression of DEK, and silencing DEK attenuated the malignant behaviors of LSCC cells. In conclusion, PAK2 could bind to the transcription factor SOX2 and thus activate the expression of DEK, thereby driving the malignant phenotypes of LSCC cells both in vivo and in vitro.

Loss of KAP3 decreases intercellular adhesion and impairs intracellular transport of laminin in signet ring cell carcinoma of the stomach

Signet-ring cell carcinoma (SRCC) is a unique subtype of gastric cancer that is impaired for cell-cell adhesion. The pathogenesis of SRCC remains unclear. Here, we show that expression of kinesin-associated protein 3 (KAP3), a cargo adaptor subunit of the kinesin superfamily protein 3 (KIF3), a motor protein, is specifically decreased in SRCC of the stomach. CRISPR/Cas9-mediated gene knockout experiments indicated that loss of KAP3 impairs the formation of circumferential actomyosin cables by inactivating RhoA, leading to the weakening of cell-cell adhesion. Furthermore, in KAP3 knockout cells, post-Golgi transport of laminin, a key component of the basement membrane, was inhibited, resulting in impaired basement membrane formation. Together, these findings uncover a potential role for KAP3 in the pathogenesis of SRCC of the stomach.

Luteolin attenuates cancer cell stemness in PTX-resistant oesophageal cancer cells through mediating SOX2 protein stability

Cancer drug resistance is a formidable obstacle that enhances cancer stem-like cell properties, tumour metastasis and relapse. Luteolin (Lut) is a natural flavonoid with strong antitumor effects. However, the underlying mechanism(s) by which Lut protects against paclitaxel-resistant (PTX-resistant) cancer cell remains unknown. Herein, we found that Lut significantly attenuated the stem-like properties of PTX-resistant cancer cells by downregulating the expression of SOX2 protein. Additionally, further study showed that Lut could inhibit the PI3K/AKT pathway to decrease the phosphorylation level of AKT(S473) and UBR5 expression, which is an ubiquitin E3 ligase that promotes SOX2 degradation. In addition, Lut also inhibited PTX-resistant cancer cell migration and invasion by blocking epithelial-mesenchymal transition (EMT). Importantly, Lut inhibited the tumorigenic ability of oesophageal PTX-resistant cancer cells and showed no obvious toxicity in vivo. Thus, Lut has potential as a promising agent for drug-resistant oesophageal cancer therapy.

Systematic Review and Meta-analysis of the Most Common Genetic Mutations in Esophageal Squamous Cell Carcinoma

PURPOSE

Esophageal cancer is the second most common cancer among men and women. There is a need to systematically assess the current evidence to map out the contribution of genetic factors in the development of esophageal squamous cell carcinoma (ESCC).

METHODS

A literature search was carried out on published and unpublished studies up to August 2021 in Medline (PubMed), Embase (Ovid), Scopus, Proquest, Web of Science, and Google scholar. Studies that have reported the frequency of genetic mutations in ESCC were included in this study.

RESULTS

A total of 1238 titles were retrieved through searches, and finally, 56 articles, including 8114 samples, met our predefined inclusion criteria. Of the included studies, 31 were conducted in China, 12 in Japan, and the remaining were conducted in various nations, including Brazil, Korea, and Iran. Most of our included studies evaluated the TP53 (n = 37 studies) and PIK3CA (n = 30 studies) gene mutations. TP53 (68.6%; 95% CI: 61.6-74.9), CCND1 (39.3%; 95% CI: 26.2-54.1), MDM2 (24.9%; 95% CI: 9.5-51.0), NOTCH1/2/3 (17.9%; 95% CI: 15.0-21.2), KMT2D (17.4%; 95% CI: 12.4-23.8), CDKN2A (15.0%; 95% CI: 8.1-26.1), PIK3CA (13.8%; 95% CI: 10.3-18.1), FAT1 (13.3%; 95% CI: 11.7-15.0), and EGFR (9.9%; 95% CI: 5.6-17.0) were the most common involved genetic factors in developing ESCC.

CONCLUSION

This systematic review and meta-analysis revealed that more than 10% of ESCC patients had changes in TP53, CCND1, MDM2, NOTCH1/2/3, KMT2D, CDKN2A, PIK3CA, and FAT1 genes, which can highlight their role in developing ESCC. TP53, CCND1, and MDM2 are the most prevalent, demonstrating 68.6%, 39.3%, and 24.9% of the mutations in ESCC patients.

Concurrent targeting of MAP3K3 and BRD4 by miR-3140-3p overcomes acquired resistance to BET inhibitors in neuroblastoma cells

Neuroblastoma (NB) harboring MYCN amplification is a refractory disease with a poor prognosis. As BRD4, an epigenetic reader belonging to the bromodomain and extra terminal domain (BET) family, drives transcription of MYCN in NB cells, BET inhibitors (BETis) are considered useful for NB therapy. However, clinical trials of BETis suggested that early acquired resistance to BETis limits their therapeutic benefit. MicroRNAs are small non-coding RNAs that mediate post-transcriptional silencing of target genes. We previously identified miR-3140-3p as a potent candidate for nucleic acid therapeutics for cancer, which directly targets BRD4. We demonstrated that miR-3140-3p suppresses tumor cell growth in MYCN-amplified NB by downregulating MYCN and MYC through BRD4 suppression. We established BETi-acquired resistant NB cells to evaluate the mechanism of resistance to BETi in NB cells. We revealed that activated ERK1/2 stabilizes MYCN protein by preventing ubiquitin-mediated proteolysis via phosphorylation of MYCN at Ser62 in BETi-acquired resistant NB cells, thereby attenuating the effects of BETi in these cells. miR-3140-3p efficiently downregulated MYCN expression by directly targeting the MAP3K3-ERK1/2 pathway in addition to BRD4 suppression, inhibiting tumor cell growth in BETi-acquired resistant NB cells. This study suggests that miR-3140-3p has the potential to overcome resistance to BETi in NB.

SOX2 enhances cell survival and induces resistance to apoptosis under serum starvation conditions through the AKT/GSK-3β signaling pathway in esophageal squamous cell carcinoma

The human SOX2 gene was recently identified as a novel major oncogene, recurrently amplified and overexpressed in esophageal squamous cell carcinoma (ESCC). However, the role and molecular mechanism of SOX2 in the carcinogenesis of ESCC remain to be elucidated. The present study investigated the effect of SOX2 on ESCC cell survival and resistance to apoptosis under serum starvation conditions. An adenoviral vector-mediated expression system and RNA interference were used to study the effect of SOX2. The present results revealed that SOX2 promoted ESCC cell survival and enhanced resistance to apoptosis under serum starvation conditions, but not in culture conditions with serum. Mechanistically, SOX2 increased the expression levels of phosphorylated AKT and glycogen synthase kinase-3β (GSK-3β), a downstream factor of AKT, under serum starvation conditions, leading to the promotion of ESCC cell survival. Additionally, SOX2 activated AKT through the PTEN/PI3K/phosphoinositide-dependent protein kinase 1 and mammalian target of rapamycin complex 2 signaling pathways. Therefore, SOX2 may facilitate the survival of ESCC cells under poor nutrient conditions by activating the AKT/GSK-3β signaling pathway.

SOX2 amplification and chromosome 3 gain significantly impact prognosis in esophageal squamous cell carcinoma

Background

We aimed to investigate the prevalence and prognostic role of Sex determining region Y-box 2 (SOX2) amplification and expression in surgically resected esophageal squamous cell carcinoma (ESCC).

Methods

We evaluated 450 ESCC samples using fluorescence in-situ hybridization and immunohistochemistry for SOX2 gene amplification and protein expression, respectively. The relationships of gene status with various clinicopathological characteristics and patient survival were statistically analyzed.

Results

SOX2 amplifications and chromosome 3 gain were observed in 4.4% and 12.9% of patients with ESCC. SOX2 amplification was associated with later clinical stage, and chromosome 3 gain was associated with earlier clinical stage (P=0.025). Low and high SOX2 expression were found in 28.9% and 24.7% of cases, respectively. SOX2 expression was significantly associated with gene copy number variation (P=0.007). SOX2 amplification was associated with a significantly shorter disease-free survival (DFS) or overall survival (OS). However, chromosome 3 gain was associated with a significantly longer DFS or OS (P<0.001). Multivariate analysis using the Cox proportional hazard model indicated that SOX2 amplification was an independently poorer prognostic factor (DFS, P<0.001, HR 2.638, 95% CI, 1.581–4.403; OS, P<0.001, HR 2.608, 95% CI, 1.562–4.355), along with pathology tumor-node-metastasis (pTNM) stage, whereas chromosome 3 gain was an independently better prognostic factor (DFS, P=0.003, HR 0.486, 95% CI, 0.300–0.789; OS, P=0.003, HR 0.474, 95% CI, 0.289–0.779) for ESCC.

Conclusions

This is the first study wherein SOX2 amplification and chromosome 3 gain in a large cohort of ESCC were evaluated. SOX2 amplification is an independently poorer prognostic factor, whereas chromosome 3 gain is an independently favorable prognostic factor. Our results suggest that SOX2 amplification and chromosome 3 gain are potential biomarkers related to tumor progression and risk stratification in ESCC.

SOX2 and squamous cancers

SOX2 is a pleiotropic nuclear transcription factor with major roles in stem cell biology and in development. Over the last 10 years SOX2 has also been implicated as a lineage-specific oncogene, notably in squamous carcinomas but also neurological tumours, particularly glioblastoma. Squamous carcinomas (SQCs) comprise a common group of malignancies for which there are no targeted therapeutic interventions. In this article we review the molecular epidemiological and laboratory evidence linking SOX2 with squamous carcinogenesis, explore in detail the multifaceted impact of SOX2 in SQC, describe areas of uncertainty and highlight areas for potential future research.

Sox2 induces tumorigenesis and angiogenesis of early-stage esophageal squamous cell carcinoma through secretion of Suprabasin

Early stage of esophageal squamous cell carcinoma (ESCC) is known to be accompanied by angiogenesis and morphological changes of microvessels. Transcription factor Sox2 is amplified in various cancers including ESCC, but the role of Sox2 in the carcinogenesis and angiogenesis has not been determined. Hence, we aimed to investigate the role of Sox2 in the early stage of ESCC. We found that the expression of Sox2 was significantly higher in early-stage ESCC tissues than that in their adjacent normal tissues. We then established Sox2-inducible normal human esophageal squamous cell line (HetSox2) to investigate the role of Sox2 in esophageal carcinogenesis and angiogenesis in vitro. Sox2 overexpression led to increased cell proliferation and spheroid formation. The culture supernatant of Sox2-overexpressing HetSox2 induced migration and sprouting of endothelial cell line HUVEC (human umbilical vein endothelial cell). As for the mechanism, we found that the expression of secreted protein Suprabasin was directly induced by Sox2. Suprabasin enhanced proliferation of normal human esophageal squamous cells when added to the culture. Moreover, Suprabasin enhanced migration and sprouting of HUVEC cells, which were observed with the culture supernatant of Sox2-overexpressing HetSox2. This angiogenic effect of Suprabasin was abolished by inhibiting AKT phosphorylation, which suggested its dependence on AKT signaling. Finally, we showed that Suprabasin expression and the density of microvessels were significantly higher in ESCC tissues with high Sox2 expression. Our study suggested that increased Sox2 expression in esophageal squamous cells induced Suprabasin expression, and as a result initiated the carcinogenesis via increased cell proliferation and angiogenesis.

TP63 links chromatin remodeling and enhancer reprogramming to epidermal differentiation and squamous cell carcinoma development

Squamous cell carcinoma (SCC) is an aggressive malignancy that can originate from various organs. TP63 is a master regulator that plays an essential role in epidermal differentiation. It is also a lineage-dependent oncogene in SCC. ΔNp63α is the prominent isoform of TP63 expressed in epidermal cells and SCC, and overexpression promotes SCC development through a variety of mechanisms. Recently, ΔNp63α was highlighted to act as an epidermal-specific pioneer factor that binds closed chromatin and enhances chromatin accessibility at epidermal enhancers. ΔNp63α coordinates chromatin-remodeling enzymes to orchestrate the tissue-specific enhancer landscape and three-dimensional high-order architecture of chromatin. Moreover, ΔNp63α establishes squamous-like enhancer landscapes to drive oncogenic target expression during SCC development. Importantly, ΔNp63α acts as an upstream regulator of super enhancers to activate a number of oncogenic transcripts linked to poor prognosis in SCC. Mechanistically, ΔNp63α activates genes transcription through physically interacting with a number of epigenetic modulators to establish enhancers and enhance chromatin accessibility. In contrast, ΔNp63α also represses gene transcription via interacting with repressive epigenetic regulators. ΔNp63α expression is regulated at multiple levels, including transcriptional, post-transcriptional, and post-translational levels. In this review, we summarize recent advances of p63 in epigenomic and transcriptional control, as well as the mechanistic regulation of p63.

Long Noncoding RNA DANCR Regulates Cell Proliferation by Stabilizing SOX2 mRNA in Nasopharyngeal Carcinoma

The long noncoding RNA DANCR (differentiation antagonizing non-protein coding RNA) displays aberrant expression in various cancers. However, its clinical value and functional mechanisms in nasopharyngeal carcinoma (NPC) remain poorly understood. We found that DANCR is dramatically up-regulated in human NPC, and that it is an indicator for poor survival prognosis. DANCR knockdown suppressed cell proliferation, colony formation in vitro, and tumorigenicity in vivo. Mechanistic analyses demonstrated that DANCR could bind to RNA-binding protein 3 (RBM3) protein and stabilize SOX2 mRNA, resulting in NPC cell proliferation. Our findings indicate that DANCR functions as an oncogene and a potential therapeutic target for NPC.

The Pathologic and Molecular Landscape of Esophageal Squamous Cell Carcinogenesis

Esophageal squamous cell carcinoma represents the most common histotype of epithelial neoplasm occurring within esophageal mucosa worldwide. Despite the comprehensive molecular characterization of this entity, to date no significant targeted therapy has been introduced into clinical practice. In this review, we describe the molecular landscape of esophageal squamous cell carcinoma based on the most recent literature. Moreover, we focus on other rare variants and on the relationship with head and neck squamous cell carcinomas.

Functional characterization of SOX2 as an anticancer target

SOX2 is a well-characterized pluripotent factor that is essential for stem cell self-renewal, reprogramming, and homeostasis. The cellular levels of SOX2 are precisely regulated by a complicated network at the levels of transcription, post-transcription, and post-translation. In many types of human cancer, SOX2 is dysregulated due to gene amplification and protein overexpression. SOX2 overexpression is associated with poor survival of cancer patients. Mechanistically, SOX2 promotes proliferation, survival, invasion/metastasis, cancer stemness, and drug resistance. SOX2 is, therefore, an attractive anticancer target. However, little progress has been made in the efforts to discover SOX2 inhibitors, largely due to undruggable nature of SOX2 as a transcription factor. In this review, we first briefly introduced SOX2 as a transcription factor, its domain structure, normal physiological functions, and its involvement in human cancers. We next discussed its role in embryonic development and stem cell-renewal. We then mainly focused on three aspects of SOX2: (a) the regulatory mechanisms of SOX2, including how SOX2 level is regulated, and how SOX2 cross-talks with multiple signaling pathways to control growth and survival; (b) the role of SOX2 in tumorigenesis and drug resistance; and (c) current drug discovery efforts on targeting SOX2, and the future perspectives to discover specific SOX2 inhibitors for effective cancer therapy.

Ultrasensitive microfluidic electrochemical immunosensor based on electrodeposited nanoporous gold for SOX-2 determination

An ultrasensitive and portable microfluidic electrochemical immunosensor for SOX-2 cancer biomarker determination was developed. The selectivity and sensitivity of the sensor were improved by modifying the microfluidic channel. This was accomplished through a physical-chemical treatment to produce a hydrophilic surface, with an increased surface to volume/ratio, where the anti-SOX-2 antibodies can be covalently immobilized. A sputtered gold electrode was used as detector and its surface was activated by using a dynamic hydrogen bubble template method. As a result, a gold nanoporous structure (NPAu) with outstanding properties, like high specific surface area, large pore volume, uniform nanostructure, good conductivity, and excellent electrochemical activity was obtained. SOX-2 present in the sample was bound to the anti-SOX-2 immobilized in the microfluidic channel, and then was labeled with a second antibody marked with horseradish peroxidase (HRP-anti-SOX-2) like a sandwich immunoassay. Finally, an H₂O₂ + catechol solution was added, and the enzymatic product (quinone) was reduced on the NPAu electrode at +0.1 V (vs. Ag). The current obtained was directly proportional to the SOX-2 concentration in the sample. The detection limit achieved was 30 pg mL^-1, and the coefficient of variation was less than 4.75%. Therefore, the microfluidic electrochemical immunosensor is a suitable clinical device for in situ SOX-2 determination in real samples.

Integrated analysis revealing genome-wide chromosomal copy number variation in supraglottic laryngeal squamous cell carcinoma

Laryngeal squamous cell carcinoma (LSCC) is a genetically complex tumor type and one of the leading causes of cancer-associated disability and mortality. Genetic instability, such as chromosomal instability, is associated with the tumorigenesis of LSCC. Copy number variations (CNVs) have been demonstrated to contribute to the genetic diversity of tumor pathogenesis. Comparative genomic hybridization (CGH) has emerged as a high-throughput genomic technology that facilitates the aggregation of high-resolution data of cancer-associated genomic imbalances. In the present study, a total of 38 primary supraglottic LSCC cases were analyzed by high-resolution array-based CGH (aCGH) to improve the understanding of the genetic alterations in LSCC. Additionally, integration with bioinformatic analysis of microarray expression profiling data from the Gene Expression Omnibus (GEO) database provided a fundamental method for the identification of putative target genes. Genomic CNVs were detected in all cases. The size of net genomic imbalances per case ranged between a loss of 682.3 Mb (~24% of the genome) and a gain of 1,958.6 Mb (~69% of the genome). Recurrent gains included 2pter-q22.1, 3q26.1-qter, 5pter-p12, 7p22.3p14.1, 8p12p11.22, 8q24.13q24.3, 11q13.2q13.4, 12pter-p12.2, 18pter-p11.31 and 20p13p12.1, whereas recurrent losses included 3pter-p21.32, 4q28.1-q35.2, 5q13.2-qter, 9pter-p21.3 and monosomy 13. Gains of 3q26.1-qter were associated with tumor stage, poor differentiation and smoking history. Additionally, through integration with bioinformatic analysis of data from the GEO database, putative target oncogenes, including sex-determining region Y-box 2, eukaryotic translation initiation factor 4 gamma 1, fragile X-related gene 1, disheveled segment polarity protein 3, defective n cullin neddylation 1 domain containing 1, insulin like growth factor 2 mRNA binding protein 2 and CCDC26 long non-coding RNA, and tumor suppressor genes, such as CUB and sushi multiple domains 1, cyclin dependent kinase inhibitor 2A, protocadherin 20, serine peptidase inhibitor Kazal type 5 and Nei like DNA glycosylase 3, were identified in supraglottic LSCC. Supraglottic LSCC is a genetically complex tumor type and aCGH was demonstrated to be effective in the determination of molecular profiles with higher resolution. The present results enable the identification of putative target oncogenes and tumor suppressor gene mapping in supraglottic LSCC.

Detention and Identification of Cancer Stem Cells in Esophageal Squamous Cell Carcinoma

Cancer stem cells (CSCs) are a small subpopulation of cells associated with cancer initiation, progression, metastasis, therapy resistant, and recurrence. In esophageal squamous cell carcinoma (ESCC), several cell surface and intracellular markers, for example, CD44, ALDH, Pygo2, MAML1, Twist1, Musashi1, side population (SP), CD271, and CD90, have been proposed to identify CSCs. In addition, stem cell markers such as ALDH1, HIWI, Oct3/4, ABCG2, SOX2, SALL4, BMI-1, NANOG, CD133, and podoplanin were associated with pathological stages of cancer, cancer recurrence, prognosis, and therapy resistance of patients with ESCC. Identification and isolation of CSCs could play an important part of improved cancer management regime in ESCC. Furthermore, CSCs may be used as the predictive tool for chemoradiotherapy response in ESCC. Different methods such as in vitro functional assays, cell sorting using various intracellular, and cell surface markers and xenotransplantation techniques are frequently used for the identification and isolation of CSCs in different cancers, including ESCC. However, none of these methods solely can guarantee complete isolation of CSC population. Therefore, a combination of methods is used for reliable detection and isolation of CSCs. Herein, we describe the identification and isolation of CSCs from ESCC cells by cell sorting after Hoechst 33342 staining followed by in vitro functional assays and in vivo mouse xenotransplantation techniques.

The expression and prognostic value of SOX2, β-catenin and survivin in esophageal squamous cell carcinoma

Aim: We mainly explored the effect of SOX2, β-catenin and survivin on prognosis in esophageal squamous cell carcinoma. Materials & methods: Immunohistochemistry was used to examine the expression of SOX2, β-catenin and survivin. χ² test was used to analyze the relationship between proteins and clinicopathological parameters. Survival analysis was used to investigate the effect of three proteins on prognosis. Results: SOX2 was related to lymph node metastasis (p = 0.004) and vascular invasion (p = 0.041). β-catenin was associated with depth of invasion (p = 0.014), lymph node metastasis (p = 0.032) and postoperative chemoradiotherapy (p < 0.001). Survivin was related to gender (p = 0.022) and nerve invasion (p = 0.014). There was a positive correlation between SOX2 and β-catenin. Patients with SOX2 and β-catenin overexpression had poor prognosis. Survivin-positive patients who received postoperative chemoradiotherapy had a short time. Conclusion: SOX2, β-catenin and survivin can be used as prognostic markers of esophageal squamous cell carcinoma.

Cancer stem cells in neuroblastoma therapy resistance

Neuroblastoma (NB) is the most common cancer of infancy and accounts for nearly one tenth of pediatric cancer deaths. This mortality rate has been attributed to the > 50% frequency of relapse despite intensive, multimodal clinical therapy in patients with progressive NB. Given the disease’s heterogeneity and developed resistance, attaining a cure after relapse of progressive NB is highly challenging. A rapid decrease in the timeline between successive recurrences is likely due to the ongoing acquisition of genetic rearrangements in undifferentiated NB-cancer stem cells (CSCs). In this review, we present the current understanding of NB-CSCs, their intrinsic role in tumorigenesis, their function in disease progression, and their influence on acquired therapy resistance and tumor evolution. In particular, this review focus on the intrinsic involvement of stem cells and signaling in the genesis of NB, the function of pre-existing CSCs in NB progression and therapy response, the formation and influence of induced CSCs (iCSCs) in drug resistance and tumor evolution, and the development of a CSC-targeted therapeutic approach.

Sox2 promotes expression of the ST6Gal-I glycosyltransferase in ovarian cancer cells

Background

The ST6Gal-I glycosyltransferase, which adds α2–6-linked sialic acids to N-glycosylated proteins is upregulated in a wide range of malignancies including ovarian cancer. Prior studies have shown that ST6Gal-I-mediated sialylation of select surface receptors remodels intracellular signaling to impart cancer stem cell (CSC) characteristics. However, the mechanisms that contribute to ST6Gal-I expression in stem-like cancer cells are poorly understood.

Results

Herein, we identify the master stem cell transcription factor, Sox2, as a novel regulator of ST6Gal-I expression. Interestingly, SOX2 and ST6GAL1 are located within the same tumor-associated amplicon, 3q26, and these two genes exhibit coordinate gains in copy number across multiple cancers including ~ 25% of ovarian serious adenocarcinomas. In conjunction with genetic co-amplification, our studies suggest that Sox2 directly binds the ST6GAL1 promoter to drive transcription. ST6Gal-I expression is directed by at least four distinct promoters, and we identified the P3 promoter as the predominant promoter utilized by ovarian cancer cells. Chromatin Immunoprecipitation (ChIP) assays revealed that Sox2 binds regions proximal to the P3 promoter. To confirm that Sox2 regulates ST6Gal-I expression, Sox2 was either overexpressed or knocked-down in various ovarian cancer cell lines. Sox2 overexpression induced an increase in ST6Gal-I mRNA and protein, as well as surface α2–6 sialylation, whereas Sox2 knock-down suppressed levels of ST6Gal-I mRNA, protein and surface α2–6 sialylation.

Conclusions

These data suggest a process whereby SOX2 and ST6GAL1 are coordinately amplified in cancer cells, with the Sox2 protein then binding the ST6GAL1 promoter to further augment ST6Gal-I expression. Our collective results provide new insight into mechanisms that upregulate ST6Gal-I expression in ovarian cancer cells, and also point to the possibility that some of the CSC characteristics commonly attributed to Sox2 may, in part, be mediated through the sialyltransferase activity of ST6Gal-I.

SOX2 in development and cancer biology

The transcription factor SOX2 is essential for embryonic development and plays a crucial role in maintaining the stemness of embryonic cells and various adult stem cell populations. On the other hand, dysregulation of SOX2 expression is associated with a multitude of cancer types and it has been shown that SOX2 positively affects cancer cell traits such as the capacity to proliferate, migrate, invade and metastasize. Moreover, there is growing evidence that SOX2 mediates resistance towards established cancer therapies and that it is expressed in cancer stem cells. These findings indicate that studying the role of SOX2 in the context of cancer progression could lead to the development of new therapeutic options. In this review, the current knowledge about the role of SOX2 in development, maintenance of stemness, cancer progression and the resistance towards cancer therapies is summarized.

The Stem Cell-associated Transcription Factor SOX2 as a Diagnostic Marker of High-grade Squamous Intraepithelial Lesion of the Uterine Cervix in Comparison With p16 and Ki-67

The transcription factor SOX2 has been identified as an oncogene involved in the pathogenesis of squamous cell carcinoma (SCC) of multiple sites, including the uterine cervix. The relationship between SOX2 overexpression and the continuum of precancerous lesions of the cervix has not been previously elucidated. We evaluated SOX2 immunohistochemical expression in normal cervix, low-grade squamous intraepithelial lesion (LSIL) (mild squamous dysplasia), high-grade squamous intraepithelial lesion (HSIL) (moderate and severe dysplasia) and SCC of the cervix in comparison with p16 and Ki-67. Staining patterns were scored as negative, basal one third of the epithelium, lower two third, or full thickness. The results showed that SOX2 expression was limited to the basal one third in 84% of LSIL cases, whereas 95% of HSIL showed SOX2 expression up to two third or full thickness (P<0.0001). p16 and Ki-67 displayed similar results. The difference in SOX2 expression between moderate and severe dysplasia was not statistically significant (P=0.53). Invasive SCC positivity was as follows: SOX2 94%; p16 89%; and Ki-67 100%. Our findings support a role for SOX2 in the progression of squamous dysplasia to SCC. The Lower Anogenital Standardization Terminology Project's recent assertion of a lack of a biological correlate to cervical intraepithelial neoplasia II is also upheld by SOX2. For equivocal situations in which a diagnosis of cervical intraepithelial neoplasia II would have been made, Lower Anogenital Standardization Terminology recommends p16, or other biomarkers such as Ki-67 to clarify the diagnosis. SOX2, with a clean nuclear staining pattern, may also be suitable for this role.

AKT drives SOX2 overexpression and cancer cell stemness in esophageal cancer by protecting SOX2 from UBR5-mediated degradation

As a transcription factor critical for embryonic and adult stem cell self-renewal and function, SOX2 gene amplification has been recognized as a driving factor for various cancers including esophageal cancer. SOX2 overexpression occurs more broadly in cancer than gene amplification, but the mechanism is poorly understood. Here we showed that in esophageal cancer cell lines the levels of SOX2 proteins are not directly correlated to the copy numbers of SOX2 genes and are strongly influenced by proteostasis. We showed that AKT is a major determinant for SOX2 overexpression and does so by protecting SOX2 from ubiquitin-dependent protein degradation. We identified UBR5 as a major ubiquitin E3 ligase that induces SOX2 degradation through ubiquitinating SOX2 at lysine 115. Phosphorylation of SOX2 at threonine 116 by AKT inhibits the interaction of UBR5 with SOX2 and thus stabilizes SOX2. We provided evidence that AKT inhibitor can effectively downregulate SOX2 and suppress esopheageal cancer cell proliferation and stemness. Taken together, our study provides new insight into the mechanism of SOX2 overexpression in cancer and evidence for targeting AKT as a potential therapeutic strategy for SOX2-positive cancers.

The Novel Role of SOX2 as an Early Predictor of Cancer Risk in Patients with Laryngeal Precancerous Lesions

The SOX2 gene located at 3q26 is frequently amplified and overexpressed in multiple cancers, including head and neck squamous cell carcinomas (HNSCC). The tumor-promoting activity and involvement of SOX2 in tumor progression has been extensively demonstrated, thereby emerging as a promising therapeutic target. However, the role of SOX2 in early stages of tumorigenesis and its possible contribution to malignant transformation remain unexplored. This study investigates for the first time SOX2 protein expression by immunohistochemistry and gene amplification by real-time PCR using a large series of 94 laryngeal precancerous lesions. Correlations with the histopathological classification and the risk of progression to invasive carcinoma were established. Nuclear SOX2 expression was frequently detected in 38 (40%) laryngeal dysplasias, whereas stromal cells and normal adjacent epithelia showed negative expression. SOX2 gene amplification was detected in 18 (33%) of 55 laryngeal dysplasias. Univariate Cox analysis showed that SOX2 gene amplification (p = 0.046) and protein expression (p < 0.001) but not histological grading (p = 0.432) were significantly associated with laryngeal cancer risk. In multivariate stepwise analysis including age, tobacco, histology, SOX2 gene amplification and SOX2 expression, SOX2 expression (HR = 3.531, 95% CI 1.144 to 10.904; p = 0.028) was the only significant independent predictor of laryngeal cancer development. These findings underscore the relevant role of SOX2 in early tumorigenesis and a novel clinical application of SOX2 expression as independent predictor of laryngeal cancer risk in patients with precancerous lesions beyond current WHO histological grading. Therefore, targeting SOX2 could lead to effective strategies for both cancer prevention and treatment.

Epigenomic analysis reveals DNA motifs regulating histone modifications in human and mouse

Histones are modified by enzymes that act in a locus, cell-type, and developmental stage-specific manner. The recruitment of enzymes to chromatin is regulated at multiple levels, including interaction with sequence-specific DNA-binding factors. However, the DNA-binding specificity of the regulatory factors that orchestrate specific histone modifications has not been broadly mapped. We have analyzed 6 histone marks (H3K4me1, H3K4me3, H3K27ac, H3K27me3, K3H9me3, H3K36me3) across 121 human cell types and tissues from the NIH Roadmap Epigenomics Project as well as 8 histone marks (with addition of H3K4me2 and H3K9ac) from the mouse ENCODE Consortium. We have identified 361 and 369 DNA motifs in human and mouse, respectively, that are the most predictive of each histone mark. Interestingly, 107 human motifs are conserved between the two species. In human embryonic cell line H1, we mutated only the found DNA motifs at particular loci and the significant reduction of H3K27ac levels validated the regulatory roles of the perturbed motifs. The functionality of these motifs was also supported by the evidence that histone-associated motifs, especially H3K4me3 motifs, significantly overlap with the expression of quantitative trait loci SNPs in cancer patients more than the known and random motifs. Furthermore, we observed possible feedbacks to control chromatin dynamics as the found motifs appear in the promoters or enhancers associated with various histone modification enzymes. These results pave the way toward revealing the molecular mechanisms of epigenetic events, such as histone modification dynamics and epigenetic priming.

Targeting SOX2 in anticancer therapy

INTRODUCTION

SOX2 is a transcription factor that is important in the development and maintenance of the stem cell state. Furthermore, SOX2 is associated with cancer progression because it promotes the migration, invasion, and proliferation of cancer cells. SOX2 is also expressed in cancer stem cells and appears to be involved in the resistance toward anticancer therapies. These features render SOX2 an attractive target for cancer therapy. Areas covered: In this review, we highlight the role of SOX2 in cancer and in the resistance toward anticancer therapies. We summarize recent studies dealing with SOX2 as a direct or indirect therapeutic target in cancer. Expert opinion: SOX2 is an attractive target in cancer therapy because of its role in cancer progression and therapy resistance. SOX2 is a transcription factor, hence direct targeting is difficult. Studies aimed at a functional depletion, for example by knock-down with siRNAs, are difficult to translate into clinical settings. Alternatively, the identification of SOX2 upstream or downstream regulators that are easier to target is of paramount importance.

SOX2 recruits KLF4 to regulate nasopharyngeal carcinoma proliferation via PI3K/AKT signaling

SOX2 is a transcription factor that contributes to transcription modification and cancer, but the mechanism by which SOX2 regulates nasopharyngeal carcinoma cell proliferation is not well understood. Here, we identify a SOX2 signaling pathway that facilitates nasopharyngeal carcinoma, where it is upregulated. SOX2 expression was associated with nasopharyngeal carcinoma patient survival. SOX2 knockdown inhibited cell proliferation, colony formation, and tumorigenesis in an subcutaneous mouse xenograft model system. Six hundred and ninety-nine candidate SOX2 downstream dysregulated genes were identified in nasopharyngeal carcinoma cells through cDNA microarray analysis. SOX2 recruited the nuclear transcription factor KLF4 to bind to the PIK3CA promoter upregulate PIK3CA expression, acting to enhance PI3K/AKT signaling and tumorigenesis by upregulating PIK3CA expression. Besides, overexpressing activated AKT or PIK3CA rescued the growth inhibition of cells due to SOX2 knockdown. Together, our study suggest that SOX2 exhibits oncogenic properties and may be a reliable molecular biomarker in nasopharyngeal carcinoma. Targeting SOX2 might be a promising treatment strategy for nasopharyngeal carcinoma treatment.

The dark side of SOX2: cancer - a comprehensive overview

The pluripotency-associated transcription factor SOX2 is essential during mammalian embryogenesis and later in life, but SOX2 expression can also be highly detrimental. Over the past 10 years, SOX2 has been shown to be expressed in at least 25 different cancers. This review provides a comprehensive overview of the roles of SOX2 in cancer and focuses on two broad topics. The first delves into the expression and function of SOX2 in cancer focusing on the connection between SOX2 levels and tumor grade as well as patient survival. As part of this discussion, we address the developing connection between SOX2 expression and tumor drug resistance. We also call attention to an under-appreciated property of SOX2, its levels in actively proliferating tumor cells appear to be optimized to maximize tumor growth - too little or too much SOX2 dramatically alters tumor growth. The second topic of this review focuses on the exquisite array of molecular mechanisms that control the expression and transcriptional activity of SOX2. In addition to its complex regulation at the transcriptional level, SOX2 expression and activity are controlled carefully by microRNAs, long non-coding RNAs, and post-translational modifications. In the Conclusion and Future Perspectives section, we point out that there are still important unanswered questions. Addressing these questions is expected to lead to new insights into the functions of SOX2 in cancer, which will help design novels strategies for more effectively treating some of the most deadly cancers.

Genome wide copy number analyses of superficial esophageal squamous cell carcinoma with and without metastasis

Superficial esophageal squamous cell carcinoma (ESCC) is generally considered a subtype of less invasive ESCC. Yet a subset of these superficial ESCC would have metastasis after esophagostomy or endoscopic resection and lead to poor prognosis. The objective of this study is to determine biomarkers that can identify such subset of superficial ESCC that would have metastasis after surgery using genome wide copy number alteration (CNA) analyses. The CNAs of 38 cases of superficial ESCCs originated from radical surgery, including 19 without metastasis and 19 with metastasis within 5 years’ post-surgery, were analyzed using Affymetrix OncoScan™ FFPE Assay. A 39-gene signature was identified which characterized the subset of superficial ESCC with high risk of metastasis after surgery. In addition, recurrent CNAs of superficial ESCC were also investigated in the study. Amplification of 11q13.3 (FGF4) and deletion of 9p21.3 (CDKN2A) were found to be recurrent in all 38 superficial ESCCs analyzed. Notably amplifications of 3p26.33 (SOX2OT), 8q24.21 (MYC), 14q21.1 (FOXA1) and deletion of 3p12.1 (GBE1) were only found to be recurrent in metastaic superficial ESCCs. In conclusion, using CNAs analyses, we identify a 39-gene signature which characterizes the high risk metastatic superficial ESCCs and discover several recurrent CNAs that might be the driver alterations in metastasis among superficial ESCCs.

Comprehensive genomic profiling of head and neck squamous cell carcinoma reveals FGFR1 amplifications and tumour genomic alterations burden as prognostic biomarkers of survival

BACKGROUND

We aimed at identifying deleterious genomic alterations from untreated head and neck squamous cell carcinoma (HNSCC) patients, and assessing their prognostic value.

PATIENTS AND METHODS

We retrieved 122 HNSCC patients who underwent primary surgery. Targeted NGS was used to analyse a panel of 100 genes selected among the most frequently altered genes in HNSCC and potential therapeutic targets. We selected only deleterious (activating or inactivating) single nucleotide variations, and copy number variations for analysis. Univariate and multivariate analyses were performed to assess the prognostic value of altered genes.

RESULTS

A median of 2 (range: 0-10) genomic alterations per sample was observed. Most frequently altered genes involved the cell cycle pathway (TP53 [60%], CCND1 [30%], CDKN2A [25%]), the PI3K/AKT/MTOR pathway (PIK3CA [12%]), tyrosine kinase receptors (EGFR [9%], FGFR1 [5%]) and cell differentiation (FAT1 [7%], NOTCH1 [4%]). TP53 mutations (p = 0.003), CCND1 amplifications (p = 0.04), CDKN2A alterations (p = 0.02) and FGFR1 amplifications (p = 0.003), correlated with shorter overall survival (OS). The number of genomic alterations was significantly higher in the HPV-negative population (p = 0.029) and correlated with a shorter OS (p < 0.0001). Only TP53 mutation and FGFR1 amplification status remained statistically significant in the multivariate analysis.

CONCLUSION

These results suggest that genomic alterations involving the cell cycle (TP53, CCND1, CDKN2A), as well as FGFR1 amplifications and tumour genomic alterations burden are prognostic biomarkers and might be therapeutic targets for patients with HNSCC.

SOX2-silenced squamous cell carcinoma: a highly malignant form of esophageal cancer with SOX2 promoter hypermethylation

This study originally aimed to investigate whether the overexpression of SOX2 is associated with the poor prognosis of patients with squamous cell carcinoma of the esophagus. However, we unexpectedly found that esophageal squamous cell carcinomas completely lacking SOX2 expression showed distinct pathologic features and highly aggressive clinical courses. The study cohort consisted of 113 consecutive patients with esophageal squamous cell carcinoma who underwent surgical resection without neoadjuvant therapy. Immunostaining on tissue microarrays and whole sections revealed that 8/113 (7%) cases were entirely negative for this transcriptional factor. SOX2-negative cancers were histologically less differentiated (P=0.002) and showed higher pT and pStages (P=0.003 and 0.007, respectively) than SOX2-positive cases. A remarkable finding was widespread lymphatic infiltration distant from the primary invasive focus, which was observed in 4 SOX2-negative cancers (50%), but none of the SOX2-positive cases. All separate dysplastic lesions observed in SOX2-negative cases were also SOX2-negative. The negative expression of SOX2 appeared to be an independent poor prognostic factor (OR=7.05, 95% CI=1.27-39.0). No mutations were identified in the coding or non-coding regions of SOX2. Fluorescent in situ hybridization did not show any copy-number variations in this gene. Since the SOX2 promoter contains an extensive CpG island, SOX2-negative cases underwent methylation-specific PCR, which disclosed promoter hypermethylation in all cases. In conclusion, SOX2-silenced squamous cell carcinomas of the esophagus appear to be a minor, but distinct form of malignancy characterized by extensive lymphatic invasion, a poor prognosis, and potential association with multiple SOX2-negative neoplastic lesions. The hypermethylation of the promoter region is seemingly a critical epigenetic event leading to SOX2 silencing.

Esophageal Cancer: Genomic and Molecular Characterization, Stem Cell Compartment and Clonal Evolution

Esophageal cancer (EC) is the eighth most common cancer and is the sixth leading cause of death worldwide. The incidence of histologic subtypes of EC, esophageal adenocarcinoma (EAC) and esophageal squamous carcinoma (ESCC), display considerable geographic variation. EAC arises from metaplastic Barrett's esophagus (BE) in the context of chronic inflammation secondary to exposure to acid and bile. The main risk factors for developing ESCC are cigarette smoking and alcohol consumption. The main somatic genetic abnormalities showed a different genetic landscape in EAC compared to ESCC. EAC is a heterogeneous cancer dominated by copy number alterations, a high mutational burden, co-amplification of receptor tyrosine kinase, frequent TP53 mutations. The cellular origins of BE and EAC are still not understood: animal models supported a cellular origin either from stem cells located in the basal layer of esophageal epithelium or from progenitors present in the cardia region. Many studies support the existence of cancer stem cells (CSCs) able to initiate and maintain EAC or ESCC. The exact identification of these CSCs, as well as their role in the pathogenesis of EAC and ESCC remain still to be demonstrated. The reviewed studies suggest that current molecular and cellular characterization of EAC and ESCC should serve as background for development of new treatment strategies.

Chromosomal and Genomic Variations in Esophageal Squamous Cell Carcinoma: A Review of Technologies, Applications, and Prospections

Esophageal squamous cell carcinoma (ESCC) is one of the most common malignant tumors with poor prognosis worldwide. The poor prognosis is due to the advanced stage at the time of diagnosis and the limited clinical staging lacking significant molecular biomarkers to effectively stratify patients for treatment options. As cancer is a disease of genome instability and a resulting of accumulation of genetic alteration, mounting chromosomal and genomic technologies were developed and progressed rapidly which could be used for characterizing patients in genomics level. In this review, we summarized applications of multiple technologies and research progress at chromosomal and genomic level in ESCC.

SIX1 maintains tumor basal cells via transforming growth factor-β pathway and associates with poor prognosis in esophageal cancer

Esophageal squamous cell carcinoma (ESCC) is one of the most common malignant tumors. Although improvement in both surgical techniques and neoadjuvant chemotherapy has been achieved, the 5-year survival rate of locally advanced tumors was, at best, still 55%. Therefore, elucidation of mechanisms of the malignancy is eagerly awaited. Epithelial-mesenchymal transition (EMT) by transforming growth factor-β (TGF-β) has been reported to have critical biological roles for cancer cell stemness, whereas little is known about it in ESCC. In the current study, a transcriptional factor SIX1 was found to be aberrantly expressed in ESCCs. SIX1 cDNA transfection induced overexpression of transforming growth factors (TGFB1 and TGFB2) and its receptor (TGFBR2). Cell invasion was reduced by SIX1 knockdown and was increased in stable SIX1-transfectants. Furthermore, the SIX1-transfectants highly expressed tumor basal cell markers such as NGFR, SOX2, ALDH1A1, and PDPN. Although mock-transfectants had only a 20% PDPN-high population, SIX1-transfectants had 60-70%. In two sets of 42 and 85 ESCC patients receiving surgery alone or neoadjuvant chemoradiotherapy followed by surgery, the cases with high SIX1 mRNA and protein expression level significantly showed a poor prognosis compared with those with low levels. These SIX1 high cases also expressed the above basal cell markers, but suppressed the differentiation markers. Finally, TGF-β signaling blockade suppressed ESCC cell growth in association with the reduction of PDPN-positive tumor basal cell population. The present results suggest that SIX1 accelerates self-renewal of tumor basal cells, resulting in a poor prognosis for ESCC patients.

SOX2 regulates multiple malignant processes of breast cancer development through the SOX2/miR-181a-5p, miR-30e-5p/TUSC3 axis

BACKGROUND

High levels of SOX2 protein are correlated with increased dissemination of breast cancer. However, the underlying molecular mechanisms are not fully understood.

METHODS

In this study we investigate the role of SOX2 in breast cancer metastasis using multiple in vitro and in vivo assays including cell culture, shRNA-mediated knockdown, wound healing, colony formation, transwell chamber, xenograft and tail vein injection. Moreover, western blot, immunostaining, microarray and real-time PCR were used to determine the change of protein and miRNA levels. Luciferase assays were also used to evaluate activity which TUSC3 is a target of miR-181a-5p and miR-30e-5p, and the clinical survival relevance was analyzed by Kaplan-Meier analysis.

RESULTS

We identified a novel pathway involving SOX2 regulation of microRNAs to control the proliferation and migration of breast cancer cells. shRNA-mediated knockdown of SOX2 inhibits breast cancer cell expansion and migration. More importantly, we found that these changes are accompanied by significant reduction in the levels of two microRNAs, miR-181a-5p and miR-30e-5p. Overexpression of these two microRNAs leads to reduced protein levels of Tumor Suppressor Candidate 3 (TUSC3) in breast cancer cells; mutations of the potential binding sites in the 3'-UTR of TUSC3 abrogate the inhibitory effects of the microRNAs. We further found that upregulation of TUSC3 expression leads to reduced proliferation and migration of breast cancer cells. In human breast cancer samples the levels of TUSC3 protein are inversely correlated with those of SOX2 protein.

CONCLUSIONS

Taken together, our work reveals a novel SOX2-mediated regulatory axis that plays critical roles in the proliferation, migration and invasiveness of breast cancer cells. Targeting this axis may provide beneficial effect in the treatment of breast cancer.

Prognostic value of Sox2 expression in digestive tract cancers: A meta-analysis

The aim of the present study was to accurately evaluate the association of Sox2 expression with the survival of patients with digestive tract cancers. Relevant literatures were identified by comprehensively searching databases including the Pubmed, Embase, CBMdisc, and Wanfang (up to October 2014). A meta-analysis was performed to clarify the association between Sox2 expression and overall survival or clinicopathological parameters of patients with digestive tract cancers (esophageal, gastric, and colorectal cancers). The results showed a significant association between high Sox2 expression and poor overall survival in patients with digestive tract carcinomas (HR=1.55, 95% CI=1.04-2.31), especially for patients with esophageal cancer (HR=2.04, 95%CI=1.30-3.22), colorectal cancer (HR=1.40, 95% CI=1.04-1.89), and digestive tract adenocarcinoma (HR=1.80, 95% CI=1.12-2.89), for Europeans (HR=1.98, 95% CI=1.44-2.71) or patients who did not receive neoadjuvant treatment (HR=1.73, 95% CI=1.10-2.72). Furthermore, Sox2 over-expression was highly correlated with vascular invasion (OR=1.86, 95% CI=1.25-2.77) and poor differentiation (OR=1.88, 95% CI=1.14-3.08), especially in esophageal and colorectal cancers. In conclusion, Sox2 expression may serve as a novel prognostic factor for patients with digestive tract cancers. Over-expression of Sox2 that is correlated with vascular invasion and poor differentiation suggests poor outcomes of patients with digestive tract cancers.

Genomic Characterization of Esophageal Squamous Cell Carcinoma Reveals Critical Genes Underlying Tumorigenesis and Poor Prognosis

The genetic mechanisms underlying the poor prognosis of esophageal squamous cell carcinoma (ESCC) are not well understood. Here, we report somatic mutations found in ESCC from sequencing 10 whole-genome and 57 whole-exome matched tumor-normal sample pairs. Among the identified genes, we characterized mutations in VANGL1 and showed that they accelerated cell growth in vitro. We also found that five other genes, including three coding genes (SHANK2, MYBL2, FADD) and two non-coding genes (miR-4707-5p, PCAT1), were involved in somatic copy-number alterations (SCNAs) or structural variants (SVs). A survival analysis based on the expression profiles of 321 individuals with ESCC indicated that these genes were significantly associated with poorer survival. Subsequently, we performed functional studies, which showed that miR-4707-5p and MYBL2 promoted proliferation and metastasis. Together, our results shed light on somatic mutations and genomic events that contribute to ESCC tumorigenesis and prognosis and might suggest therapeutic targets.

Predicting the molecular role of MEIS1 in esophageal squamous cell carcinoma

The three amino acid loop extension (TALE) class myeloid ecotropic viral integration site 1 (MEIS1) homeobox gene is known to play a crucial role in normal and tumor development. In contrast with its well-described cancer stemness properties in hematopoietic cancers, little is known about its role in solid tumors like esophageal squamous cell carcinoma (ESCC). Here, we analyzed MEIS1 expression and its clinical relevance in ESCC patients and also investigated its correlation with the SOX2 self-renewal master transcription factor in the ESCC samples and in the KYSE-30 ESCC cell line. MEIS1 mRNA and protein expression were significantly decreased in ESCC disease (P < 0.05). The inverse correlation between MEIS1 mRNA expression and tumor cell metastasis to the lymph nodes (P = 0.004) was significant. Also, MEIS1 protein levels inversely correlated to lymph node involvement (P = 0.048) and high tumor stage (stages III/IV, P = 0.030). The low levels of DNA methylation in the MEIS1 promoter showed that this suppression does not depend on methylation. We showed that downregulation of EZH2 restored MEIS1 expression significantly. Also, we investigated that MEIS1 downregulation is concomitant with increased SOX2 expression. To the best of our knowledge, this is the first report on the MEIS1 gene in ESCC. The inverse correlation of MEIS1 with metastasis, tumor staging, and the role of EZH2 in methylation, together with its correlation with stemness factor SOX2 expression, led us to predict cancer stemness properties for MEIS1 in ESCC.

Amplification and overexpression of CTTN and CCND1 at chromosome 11q13 in Esophagus squamous cell carcinoma (ESCC) of North Eastern Chinese Population

Esophageal squamous cell carcinoma (ESCC) is a genetically complex tumor type and is a major cause of cancer-related mortality. The combination of genetics, diet, behavior, and environment plays an important role in the carcinogenesis of ESCC. To characterize the genomic aberrations of this disease, we investigated the genomic imbalances in 19 primary ESCC cases using high-resolution array comparative genomic hybridization (CGH). All cases showed either loss or gain of whole chromosomes or segments of chromosome(s) with variable genomic sizes. The copy number alterations per case affected the median 34% (~ 1,034Mb/3,000Mb) of the whole genome. Recurrent gains were 1q21.3-qter, 3q13.11-qter, 5pter-p11, 7pter-p15.3, 7p12.1-p11.2, 7q11-q11.2, 8p12-qter, 11q13.2-q13.3, 12pter-p13.31, 17q24.2, 20q11.21-qter, and 22q11.21-q11.22 whereas the recurrent losses were 3pter-p11.1, 4pter-p12, 4q28.3-q31.22, 4q31.3-q32.1, 9pter-p12, 11q22.3-qter and 13q12.11-q22.1. Amplification of 11q13 resulting in overexpression of CTTN/CCND1 was the most prominent finding, which was observed in 13 of 19 ESCC cases. These unique profiles of copy number alteration should be validated by further studies and need to be taken into consideration when developing biomarkers for early detection of ESCC.

Genetic variants in miR-196a2 and miR-499 are associated with susceptibility to esophageal squamous cell carcinoma in Chinese Han population

Esophageal squamous cell carcinoma (ESCC) is the dominant type of esophageal cancer in the East Asian population. MicroRNAs (miRNAs) have been studied to play important roles in tumorigenesis. Single nucleotide polymorphisms (SNPs) in miRNA lead to the aberrant expression and structural alteration of miRNA and are hypothesized to be involved in tumorigenesis and cancer development. We conducted a population-based case-control study to evaluate the association between SNPs in miRNAs and ESCC risk in 1400 ESCC cases and 2185 matched controls. Four SNPs including miR-196a2 rs11614913, miR-146a rs2910164, miR-499 rs3746444, and miR-423 rs6505162 were selected with comprehensive collection strategy and genotyped using the SNaPshot Multiplex System. Odds ratio (OR) and 95 % confidence interval (95 % CI) were used to assess the strength of association. The CC genotype of miR-196a2 rs11614913 was significantly associated with an increased ESCC risk compared with the TT genotype (OR 1.11, 95 % CI 1.01-1.22, P 0.049) and the TT/TC genotypes (OR 1.09, 95 % CI 1.01-1.19, P 0.043). The association was more pronounced in non-drinkers in the recessive model (OR 1.13, 95 % CI 1.01-1.27, P 0.029). A significantly increased risk of ESCC associated with miR-499 rs3746444 polymorphism was evident among patients who never smoking and drinking. This study suggests that miR-196a2 rs11614913 and miR-499 rs3746444 are associated with an increased ESCC risk in a Chinese population.

Cancer stem cells in oesophageal squamous cell carcinoma: Identification, prognostic and treatment perspectives

Cancer stem cells (CSCs) are a vital subpopulation of cells to target for the treatment of cancers. In oesophageal squamous cell carcinoma (ESCC), there are several markers such as CD44, ALDH, Pygo2, MAML1, Twist1, Musashi1, Side population (SP), CD271 and CD90 that have been proposed to identify the cancer stem cells in individual cancer masses. It has also been demonstrated that stem cell markers like ALDH1, HIWI, Oct3/4, ABCG2, SOX2, SALL4, BMI-1, NANOG, CD133 and podoplanin are associated with patient's prognosis, pathological stages, cancer recurrence and therapy resistance. Finding new cancer stem cell targets or designing drugs to manipulate the known molecular targets in CSCs could be useful for improvements in clinical outcomes of the disease. To conclude, data suggest that CSCs in oesophageal squamous cell carcinoma are related to resistance to therapy and poor prognosis of patients with ESCC. Therefore, innovative insights into CSC biology and CSC-targeted therapies will help to achieve more effective management of patients with oesophageal squamous cell carcinoma.

SOX2 Promotes the Epithelial to Mesenchymal Transition of Esophageal Squamous Cells by Modulating Slug Expression through the Activation of STAT3/HIF-α Signaling

The transcription factor sex determining region (Y SRY)-box 2 (SOX2) is known to play a crucial role in the maintenance of self renewal or pluripotency of undifferentiated embryonic and neuronal stem cells. An elevated expression of SOX2 has been correlated with poor prognosis of esophageal squamous cell carcinoma (ESCC). We sought to investigate the mechanism(s) by which SOX2 modulates the ESCC metastasis. The SOX2 coding DNA sequence was inserted into pCMV vector and stably transfected in ESCC cells (Eca-109). The effect of SOX2 over expression was evaluated on cell migration, invasion and epithelial to mesenchymal transition (EMT). We also measured the expression of Slug to explore if this transcription factor is involved in SOX2-mediated regulation of cell migration/invasion and EMT. In addition, we determined the role of STAT3/HIF-1α to further probe the mechanism of SOX2-mediated metastasis via Slug. Our results demonstrated that SOX2 over expressing Eca-109 cells showed an enhanced cell migration/invasion. Moreover, these cells exhibited the EMT characteristics, that is, a significantly suppressed expression of the epithelial cells marker with a concomitant enhancement of those of the mesenchymal markers. An increased expression of Slug in SOX2 over expressing cells suggested the involvement of this transcription factor in SOX2-regulated metastasis. Whereas the expressions of STAT3/HIF-1α were found to be up-regulated in SOX2 expressing cells, blockade of these transcription factors resulted in the inhibition of Slug expression at both protein and mRNA levels. Conclusion: These results suggest that SOX2 promoted the metastasis of ESCC, at least in part, by modulating Slug expression through the activation of STAT3/HIF-1α signaling.

Esophageal Cancer: Insights From Mouse Models

Esophageal cancer is the eighth leading cause of cancer and the sixth most common cause of cancer-related death worldwide. Despite recent advances in the development of surgical techniques in combination with the use of radiotherapy and chemotherapy, the prognosis for esophageal cancer remains poor. The cellular and molecular mechanisms that drive the pathogenesis of esophageal cancer are still poorly understood. Hence, understanding these mechanisms is crucial to improving outcomes for patients with esophageal cancer. Mouse models constitute valuable tools for modeling human cancers and for the preclinical testing of therapeutic strategies in a manner not possible in human subjects. Mice are excellent models for studying human cancers because they are similar to humans at the physiological and molecular levels and because they have a shorter gestation time and life cycle. Moreover, a wide range of well-developed technologies for introducing genetic modifications into mice are currently available. In this review, we describe how different mouse models are used to study esophageal cancer.