SOX2 is frequently downregulated in gastric cancers and inhibits cell growth through cell-cycle arrest and apoptosis

SOX2, a predictor of survival in gastric cancer, inhibits cell proliferation and metastasis by regulating PTEN

Inconsistent results of SOX2 expression have been reported in gastric cancer (GC). Here, we demonstrated that SOX2 was progressively downregulated during GC development via immunochemistry in 755 human gastric specimens. Low SOX2 levels were associated with pathological stage and clinical outcome. Multivariate analysis indicated that SOX2 protein expression served as an independent prognostic marker for GC. Gain-and loss-of function studies showed the anti-proliferative, anti-metastatic, and pro-apoptotic effects of SOX2 in GC. PTEN was selected as SOX2 targets by cDNA microarray and ChIP-DSL, further identified by luciferase assays, EMSA and ChIP-PCR. PTEN upregulation in response to SOX2-enforced expression suppressed GC malignancy via regulating Akt dephosphorylation. PTEN inhibition reversed SOX2-induced anticancer effects. Moreover, concordant positivity of SOX2 and PTEN proteins in nontumorous tissues but lost in matched GC specimens predicted a worse patient prognosis. Thus, SOX2 proved to be a new marker for evaluating GC outcome.

Aberrant SOX11 promoter methylation is associated with poor prognosis in gastric cancer

BACKGROUND

Gastric cancer (GC) is the second most common cause of cancer mortality world-wide. In recent years, aberrant SOX11 expression has been observed in various solid and hematopoietic malignancies, including GC. In addition, it has been reported that SOX11 expression may serve as an independent prognostic factor for the survival of GC patients. Here, we assessed the SOX11 gene promoter methylation status in various GC cell lines and primary GC tissues, and evaluated its clinical significance.

METHODS

Five GC cell lines were used to assess SOX11 expression by qRT-PCR. The effect of SOX11 expression restoration after 5-aza-2'-deoxycytidine (5-Aza-dC) treatment on GC growth was evaluated in GC cell line MKN45. Subsequently, 89 paired GC-normal gastric tissues were evaluated for their SOX11 gene promoter methylation status using methylation-specific PCR (MSP), and 20 paired GC-normal gastric tissues were evaluated for their SOX11 expression in relation to SOX11 gene promoter methylation. GC patient survival was assessed by Kaplan-Meier analyses and a Cox proportional hazard model was employed for multivariate analyses.

RESULTS

Down-regulation of SOX11 mRNA expression was observed in both GC cell lines and primary GC tissues. MSP revealed hyper-methylation of the SOX11 gene promoter in 55.1% (49/89) of the primary GC tissues tested and in 7.9% (7/89) of its corresponding non-malignant tissues. The SOX11 gene promoter methylation status was found to be related to the depth of GC tumor invasion, Borrmann classification and GC differentiation status. Upon 5-Aza-dC treatment, SOX11 expression was found to be up-regulated in MKN45 cells, in conjunction with proliferation inhibition. SOX11 gene promoter hyper-methylation was found to be significantly associated with a poor prognosis and to serve as an independent marker for survival using multivariate Cox regression analysis.

CONCLUSIONS

Our results indicate that aberrant SOX11 gene promoter methylation may underlie its down-regulation in GC. SOX11 gene promoter hyper-methylation may serve as a biomarker to predict the clinical outcome of GC.

The overexpression of SOX2 affects the migration of human teratocarcinoma cell line NT2/D1

The altered expression of the SOX2 transcription factor is associated with oncogenic or tumor suppressor functions in human cancers. This factor regulates the migration and invasion of different cancer cells. In this study we investigated the effect of constitutive SOX2 overexpression on the migration and adhesion capacity of embryonal teratocarcinoma NT2/D1 cells derived from a metastasis of a human testicular germ cell tumor. We detected that increased SOX2 expression changed the speed, mode and path of cell migration, but not the adhesion ability of NT2/D1 cells. Additionally, we demonstrated that SOX2 overexpression increased the expression of the tumor suppressor protein p53 and the HDM2 oncogene. Our results contribute to the better understanding of the effect of SOX2 on the behavior of tumor cells originating from a human testicular germ cell tumor. Considering that NT2/D1 cells resemble cancer stem cells in many features, our results could contribute to the elucidation of the role of SOX2 in cancer stem cells behavior and the process of metastasis.

Sex-determining region of Y chromosome-related high-mobility-group box 2 in malignant tumors: current opinions and anticancer therapy

OBJECTIVE

To gain insight into the mechanism by which sex-determining region of Y chromosome (SRY)-related high-mobility-group box 2 (SOX2) involved in carcinogenesis and cancer stem cells (CSCs).

DATA SOURCES

The data used in this review were mainly published in English from 2000 to present obtained from PubMed. The search terms were "SOX2," "cancer," "tumor" or "CSCs."

STUDY SELECTION

Articles studying the mitochondria-related pathologic mechanism and treatment of glaucoma were selected and reviewed.

RESULTS

SOX2, a transcription factor that is the key in maintaining pluripotent properties of stem cells, is a member of SRY-related high-mobility group domain proteins. SOX2 participates in many biological processes, such as modulation of cell proliferation, regulation of cell death signaling, cell apoptosis, and most importantly, tumor formation and development. Although SOX2 has been implicated in the biology of various tumors and CSCs, the findings are highly controversial, and information regarding the underlying mechanism remains limited. Moreover, the mechanism by which SOX2 involved in carcinogenesis and tumor progression is rather unclear yet.

CONCLUSIONS

Here, we review the important biological functions of SOX2 in different tumors and CSCs, and the function of SOX2 signaling in the pathobiology of neoplasia, such as Wnt/β-catenin signaling pathway, Hippo signaling pathway, Survivin signaling pathway, PI3K/Akt signaling pathway, and so on. Targeting towards SOX2 may be an effective therapeutic strategy for cancer therapy.

Clinical Significance of MLH1 Methylation and CpG Island Methylator Phenotype as Prognostic Markers in Patients with Gastric Cancer

BACKGROUND

To improve the outcome of patients suffering from gastric cancer, a better understanding of underlying genetic and epigenetic events in this malignancy is required. Although CpG island methylator phenotype (CIMP) and microsatellite instability (MSI) have been shown to play pivotal roles in gastric cancer pathogenesis, the clinical significance of these events on survival outcomes in patients with gastric cancer remains unknown.

METHODS

This study included a patient cohort with pathologically confirmed gastric cancer who had surgical resections. A cohort of 68 gastric cancers was analyzed. CIMP and MSI statuses were determined by analyzing promoter CpG island methylation status of 28 genes/loci, and genomic instability at 10 microsatellite markers, respectively. A Cox's proportional hazards model was performed for multivariate analysis including age, stage, tumor differentiation, KRAS mutation status, and combined CIMP/MLH1 methylation status in relation to overall survival (OS).

RESULTS

By multivariate analysis, longer OS was significantly correlated with lower pathologic stage (P = 0.0088), better tumor differentiation (P = 0.0267) and CIMP-high and MLH1 3' methylated status (P = 0.0312). Stratification of CIMP status with regards to MLH1 methylation status further enabled prediction of gastric cancer prognosis.

CONCLUSIONS

CIMP and/or MLH1 methylation status may have a potential to be prognostic biomarkers for patients with gastric cancer.

SOX2 as prognostic factor in head and neck cancer: a systematic review and meta-analysis

CONCLUSION

SOX2-positive head and neck cancer patients had a worse prognosis, and this was associated with common clinicopathological poor prognostic factors.

OBJECTIVE

To investigate the correlation between SOX2-positive head and neck cancer and clinicopathological features and its impact on survival.

METHODS

A search in PubMed and Chinese CNKI (up to 1 July 2013) was performed. Only articles in which SOX2 antigen was detected in situ localization by immunohistochemical staining were included. This meta-analysis was done using RevMan 5.2 software. Outcomes included overall survival and various clinicopathological features.

RESULTS

A total of 926 gastric cancer patients from 9 studies were included. Meta-analysis showed that patients with SOX2 expression had a significantly worse 5-year overall survival compared with those with low expression (relative risk (RR) = 2.38, 95% confidence interval (CI) = 1.10-5.15, p = 0.03, random-effect). With respect to clinicopathological features, SOX2 overexpression as assessed by the immunohistochemistry method was closely correlated with tumor T stage, lymph node metastasis, and TNM stage.

Functional linc-POU3F3 is overexpressed and contributes to tumorigenesis in glioma

Growing number of long intergenic noncoding RNAs (lincRNAs) have recently been identified in mammals as new modulators in cancer origination and progression involved in a broad range of biological processes. Long intergenic noncoding RNA POU3F3 (linc-POU3F3) has been characterized as a highly conserved functional transcription regulator in esophageal squamous cell carcinoma. The contributions of this lincRNA to glioblastoma remain unknown. In this present study, we investigated the expression pattern and functional role of linc-POU3F3 in glioma by using real-time PCR and gain-/loss-of-function studies. The results revealed that linc-POU3F3 levels were extraordinarily associated with the tumor WHO grade. In related biochemical assays, overexpression of linc-POU3F3 promotes cell viability and proliferation in glioma cells, whereas knockdown of linc-POU3F3 showed the opposite effect. As expected, we also found that linc-POU3F3 expression was negatively correlated with the mRNA level of POU3F3 (the evolutionarily conserved neighbor gene of linc-POU3F3). Our results indicate that linc-POU3F3 might affect glioma development via altering expression level of POU3F3, and lead us to believe that linc-POU3F3 may also have a crucial regulatory role in glioma progression.

Immunohistochemical molecular phenotypes of gastric cancer based on SOX2 and CDX2 predict patient outcome

Background

Gastric cancer remains a serious health concern worldwide. Patients would greatly benefit from the discovery of new biomarkers that predict outcome more accurately and allow better treatment and follow-up decisions. Here, we used a retrospective, observational study to assess the expression and prognostic value of the transcription factors SOX2 and CDX2 in gastric cancer.

Methods

SOX2, CDX2, MUC5AC and MUC2 expression were assessed in 201 gastric tumors by immunohistochemistry. SOX2 and CDX2 expression were crossed with clinicopathological and follow-up data to determine their impact on tumor behavior and outcome. Moreover, SOX2 locus copy number status was assessed by FISH (N = 21) and Copy Number Variation Assay (N = 62).

Results

SOX2 was expressed in 52% of the gastric tumors and was significantly associated with male gender, T stage and N stage. Moreover, SOX2 expression predicted poorer patient survival, and the combination with CDX2 defined two molecular phenotypes, SOX2⁺CDX2^- versus SOX2^-CDX2⁺, that predict the worst and the best long-term patients’ outcome. These profiles combined with clinicopathological parameters stratify the prognosis of patients with intestinal and expanding tumors and in those without signs of venous invasion. Finally, SOX2 locus copy number gains were found in 93% of the samples reaching the amplification threshold in 14% and significantly associating with protein expression.

Conclusions

We showed, for the first time, that SOX2 combined with CDX2 expression profile in gastric cancer segregate patients into different prognostic groups, complementing the clinicopathological information. We further demonstrate a molecular mechanism for SOX2 expression in a subset of gastric cancer cases.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-753) contains supplementary material, which is available to authorized users.

Preoperative low dose NSAID treatment influences the genes for stemness, growth, invasion and metastasis in colorectal cancer

Preclinical data, and an increasing list of clinical investigations, show anti-inflammatory agents to favourably influence the biology of colorectal tumor. We have earlier reported on re-expression of activated immune cells after three days preoperative treatment of patients with colorectal carcinoma, randomized to receive oral NSAID (indomethacin or celebrex). Antisecretory prophylaxis (esomeprasol) was provided to all patients and served as sham treatment. Concomittant to MHC locus activation, Prominin1/CD133, a marker associated with stemness and poor prognosis in several solid tumors, was downregulated. The aim of the present study was to evaluate expression of additional regulators belonging to the stem cell niche, OCT4, SOX2 and BMP7, as well as some microRNAs, reported to act as tumor suppressors or oncomiRs. Peroperative tumor biopsies were analyzed by microarrays, quantitative real-time PCR and immunohistochemistry (IHC). The stem cell master regulator SOX2 was increased by NSAIDs (p<0.01), as well as the tumor suppressor miR-630 (p<0.01), while BMP7, a marker for poor prognosis in CRC, was downregulated by NSAID (indomethacin, p<0.02). The upregulation of SOX2, but not of its heterodimer binding partner OCT4, could imply a negative feed-back loop, with a switch‑off for stemness preservation of tumor cells. This is supported by the overall evaluation of gene expression profiles with subsequent events, indicating less aggressive tumors following NSAID treatment.

An integrated analysis of the SOX2 microRNA response program in human pluripotent and nullipotent stem cell lines

Background

SOX2 is a core component of the transcriptional network responsible for maintaining embryonal carcinoma cells (ECCs) in a pluripotent, undifferentiated state of self-renewal. As such, SOX2 is an oncogenic transcription factor and crucial cancer stem cell (CSC) biomarker in embryonal carcinoma and, as more recently found, in the stem-like cancer cell component of many other malignancies. SOX2 is furthermore a crucial factor in the maintenance of adult stem cell phenotypes and has additional roles in cell fate determination. The SOX2-linked microRNA (miRNA) transcriptome and regulome has not yet been fully defined in human pluripotent cells or CSCs. To improve our understanding of the SOX2-linked miRNA regulatory network as a contribution to the phenotype of these cell types, we used high-throughput differential miRNA and gene expression analysis combined with existing genome-wide SOX2 chromatin immunoprecipitation (ChIP) data to map the SOX2 miRNA transcriptome in two human embryonal carcinoma cell (hECC) lines.

Results

Whole-microRNAome and genome analysis of SOX2-silenced hECCs revealed many miRNAs regulated by SOX2, including several with highly characterised functions in both cancer and embryonic stem cell (ESC) biology. We subsequently performed genome-wide differential expression analysis and applied a Monte Carlo simulation algorithm and target prediction to identify a SOX2-linked miRNA regulome, which was strongly enriched with epithelial-to-mesenchymal transition (EMT) markers. Additionally, several deregulated miRNAs important to EMT processes had SOX2 binding sites in their promoter regions.

Conclusion

In ESC-like CSCs, SOX2 regulates a large miRNA network that regulates and interlinks the expression of crucial genes involved in EMT.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-711) contains supplementary material, which is available to authorized users.

Carbon ion beam is more effective to induce cell death in sphere-type A172 human glioblastoma cells compared with X-rays

PURPOSE

To obtain human glioblastoma cells A172 expressing stem cell-related protein and comparison of radiosensitivity in these cells with X-rays and carbon beam.

METHODS

Human monolayer-type A172 glioblastoma cells were maintained in normal medium with 10% bovine serum. In order to obtain sphere-type A172 cells the medium was replaced with serum-free medium supplemented with growth factors. Both types of A172 cells were irradiated with either X-rays or carbon ion beams and their radiosensitivity was evaluated.

RESULTS

Serum-free medium induced expression of stem cell-related proteins in A172 cells along with the neurosphere-like appearance. These sphere-type cells were found resistant to both X-rays and carbon ion beams. Phosphorylation of histone H2A family member X persisted for a longer period in the cells exposed to carbon ion beams than in those exposed to X-rays and it disappeared quicker in the sphere type than in the monolayer type. Relative radioresistance of the sphere type cells was smaller for carbon ion beams than for X-rays.

CONCLUSIONS

We demonstrated that glioblastoma A172 cells with induced stem cell-related proteins turned resistant to irradiation. Accelerated heavy ion particles may have advantage over X-rays in overcoming the tumor resistance due to cell stemness.

SOX2 and cancer: current research and its implications in the clinic

SOX2 is a gene that encodes for a transcription factor belonging to the SOX gene family and contains a high-mobility group (HMG) domain, which permits highly specific DNA binding. Consequently, SOX2 functions as an activator or suppressor of gene transcription. SOX2 has been described as an essential embryonic stem cell gene and moreover, a necessary factor for induced cellular reprogramming. SOX2 research has only recently switched focus from embryogenesis and development to SOX2’s function in disease. Particularly, the role of SOX2 in cancer pathogenesis has become of interest in the field. To date, studies have shown SOX2 to be amplified in various cancer types and affect cancer cell physiology via involvement in complicated cell signaling and protein-protein interactions. Recent reviews in this field have highlighted SOX2 in mammalian physiology, development and pathology. In this review, we comprehensively compile what is known to date about SOX2’s involvement in cancer biology, focusing on the most recent findings in the fields of cellular signaling and cancer stem cells. Lastly, we underscore the role of SOX2 in the clinic and highlight new findings, which may provide novel clinical applications for SOX2 as a prognostic marker, indicator of metastasis, biomarker or potential therapeutic target in some cancer types.

CDX2 can be regulated through the signalling pathways activated by IL-6 in gastric cells

The inflammatory infiltrate of the gastric mucosa associated with Helicobacter pylori infection increases the presence of the pro-inflammatory cytokine IL-6 that activates both the SHP-2/ERK/MAPK and the JAK/STAT signalling pathways. Furthermore, the ectopic expression of CDX2 is detected in pre-neoplasic lesions associated with decreased levels of SOX2, and we found that in gastric adenocarcinomas their expression is inversely correlated. To determine the role of IL-6 in the regulation of CDX2, MKN45 that constitutively expresses p-STAT3, and NUGC-4 gastric cancer cell lines were treated with IL-6, which induced the CDX2 up-regulation and SOX2 down-regulation. ChIP assays determined that in IL-6-treated cells, c-JUN and p-STAT3 bound to CDX2 promoter in MKN45 cells whereas in NUGC-4 cells, p-STAT3 binds to and c-JUN releases from the CDX2 promoter. Specific inhibition of STAT3 and ERK1/2 phosphorylation through AG490 and U0126, respectively, and STAT3 down-regulation using shRNA verified that the SHP-2/ERK/MAPK pathway regulates the expression of CDX2 in basal conditions, and the CDX2 up-regulation by IL-6 is through the JAK/STAT pathway in NUGC-4 cells whereas in MKN45 cells both pathways contribute to the CDX2 up-regulation. In conclusion, the signalling pathways activated by IL-6 have a crucial role in the regulation of CDX2 that is a key factor in the process of gastric carcinogenesis, suggesting that the inflammatory infiltrate in the gastric mucosa is relevant in this process and a potential target for new therapeutic approaches.

SOX2 enhances the migration and invasion of ovarian cancer cells via Src kinase

Ovarian cancer is the leading cause of death among gynecologic cancers and is the fifth leading cause of all cancer-related deaths among women. The development of novel molecular targets is therefore important to many patients. Recently, the SRY-related transcription factor SOX2 has been widely reported to be involved in multiple pathophysiological diseases, including maintenance of stem cell characteristics and carcinogenesis. Up to now, SOX2 has been mainly shown to promote the development of cancer, although its inhibitory roles in cancer have also been reported. However, the role of SOX2 in ovarian cancer is largely unknown. In the present study, we detected the expression of SOX2 in 64 human serous ovarian carcinoma (SOC) tissues and paired corresponding metastatic specimens using immunohistochemistry. The results showed that the expression of SOX2 in primary tumors is much lower than that in the corresponding metastatic lesions. We further found that SOX2 overexpression promotes proliferation, migration and invasion, while inhibiting adhesion abilities of SOC cells. Finally, we found that SOX2 targets Src kinase, a non-receptor tyrosine kinase that regulates cell migration, invasion and adhesion in SOC cells. Together, these results suggested that Src kinase is a key molecule in SOX2-mediated migration and invasion of SOC cells.

Influence of adriamycin on changes in Nanog, Oct-4, Sox2, ARID1 and Wnt5b expression in liver cancer stem cells

AIM: To determine the influence of Adriamycin (ADM) on the changes in Nanog, Oct4, Sox2, as well as, in ARID1 and Wnt5b expression in liver cancer stem cells.

METHODS: The MHCC97-L and HCCLM3 liver cancer cell lines were selected as the cell models in this study, and were routinely cultured. The 50% lethal dose (LD50) in the cell lines was detected by the MTT assay. Expression changes in liver cancer stem cell related genes (Nanog, Oct-4, Sox2, ARID1, and Wnt5b) were detected by western blot following treatment with ADM (LD50).

RESULTS: The LD50 of ADM in MHCC97-L cells was lower than that in HCCLM3 cells (0.4123 ± 0.0236 μmol/L vs 0.5259 ± 0.0125 μmol/L, P < 0.05). Wnt5b and Nanog were expressed in both MHCC97-L and HCCLM3 cells, while only Sox2 was expressed in HCCLM3 cells. However, neither ARID1A nor Oct4 was detected in these two cell lines. Genes, related to the stem cells, showed different expression in liver cancer cells with different metastatic potential following treatment with ADM (LD50). Wnt5b protein increased gradually within 4 h of ADM (LD50) treatment, while Nanog decreased (P < 0.05). After 12 h, Wnt5b decreased gradually, while Nanog increased steadily (P < 0.05). In addition, only Sox2 was expressed in HCCLM3 cells with high metastatic potential following ADM (LD50) treatment. The expression of Sox2 increased gradually with ADM (LD50) in HCCLM3 cells (P < 0.05).

CONCLUSION: ADM increased the death rate of MHCC97-L and HCCLM3 cells, while the growth suppressive effect of ADM was higher in MHCC97-L cells than in HCCLM3 cells.

SOX15 and other SOX family members are important mediators of tumorigenesis in multiple cancer types

SOX genes are transcription factors with important roles in embryonic development and carcinogenesis. The SOX family of 20 genes is responsible for regulating lineage and tissue specific gene expression patterns, controlling numerous developmental processes including cell differentiation, sex determination, and organogenesis. As is the case with many genes involved in regulating development, SOX genes are frequently deregulated in cancer. In this perspective we provide a brief overview of how SOX proteins can promote or suppress cancer growth. We also present a pan-cancer analysis of aberrant SOX gene expression and highlight potential molecular mechanisms responsible for their disruption in cancer. Our analyses indicate the prominence of SOX deregulation in different cancer types and reveal potential roles for SOX genes not previously described in cancer. Finally, we summarize our recent identification of SOX15 as a candidate tumor suppressor in pancreatic cancer and propose several research avenues to pursue to further delineate the emerging role of SOX15 in development and carcinogenesis.

Increased levels of the long intergenic non-protein coding RNA POU3F3 promote DNA methylation in esophageal squamous cell carcinoma cells

BACKGROUND & AIMS

Thousands of long intergenic non-protein coding RNAs (lincRNAs) have been identified in mammals via genome-wide sequencing studies. Many are functional, but are expressed aberrantly by cancer cells. We investigated whether levels of lincRNAs are altered during the development of esophageal squamous cell carcinoma (ESCC).

METHODS

We used quantitative real-time polymerase chain reaction to measure levels of 26 highly conserved lincRNAs in ESCC and surrounding nontumor tissues. A total of 182 ESCC and paired adjacent nontumor tissue samples were collected from patients undergoing tylectomy at The First Affiliate Hospital of Soochow University from 2001 through 2009; another 178 ESCC tissue pairs were collected from Guangzhou Medical University from 2002 through 2009. LincRNAs were expressed from lentiviral vectors or knocked down with small hairpin RNAs in Eca-109 and TE-1 cells.

RESULTS

Levels of a lincRNA encoded by a gene located next to POU3F3 (linc-POU3F3) were significantly higher in ESCC than neighboring nontumor tissues. In RNA immunoprecipitation assays, linc-POU3F3 was associated with the EZH2 messenger RNA (mRNA). Overexpression of linc-POU3F3 in cell lines increased their proliferation and ability to form colonies, and reduced the expression of POU3F3 mRNA, whereas knockdown of linc-POU3F3 increased the levels of POU3F3 mRNA. CpG islands in POU3F3 were densely hypermethylated in cell lines that overexpressed linc-POU3F3; methylation at these sites was reduced by knockdown of linc-POU3F3. Pharmacologic inhibition of EZH2 increased the levels of POU3F3 mRNA and significantly reduced binding of DNA methyltransferase (DNMT)1, DNMT3A, and DNMT3B to POU3F3. ESCC cells with knockdown of linc-POU3F3 formed xenograft tumors more slowly in mice than control ESCC cells.

CONCLUSIONS

Levels of linc-POU3F3 are increased in ESCC samples from patients compared with nontumor tissues. This noncoding RNA contributes to the development of ESCC by interacting with EZH2 to promote methylation of POU3F3, which encodes a transcription factor.

Expression profile of undifferentiated cell transcription factor 1 in normal and cancerous human epithelia

Undifferentiated cell Transcription Factor 1 (UTF1) is a chromatin-bound protein involved in stem cell differentiation. It was initially reported to be restricted to stem cells or germinal tissues. However, recent work suggests that UTF1 is also expressed in somatic cells and that its expression may increase during carcinogenesis. To further clarify the expression profile of UTF1, we evaluated UTF1 expression levels immunohistochemically in eight normal human epithelia (from breast, prostate, endometrium, bladder, colon, oesophagus, lung and kidney) and their corresponding tumours as well as in several epithelial cell lines. We showed UTF1 staining in normal and tumour epithelial tissues, but with varying intensities according to the tissue location. In vitro analyses also revealed that UTF1 is expressed in somatic epithelial cell lines even in the absence of Oct4A and Sox2, its two main known regulators. The comparison of UTF1 levels in normal and tumoral tissues revealed significant overexpression in endometrial and prostatic adenocarcinomas, whereas lower intensity of the staining was observed in renal and colic tumours, suggesting a potential tissue-specific function of UTF1. Altogether, these results highlight a potential dual role for UTF1, acting either as an oncogene or as a tumour suppressor depending on the tissue. These findings also question its role as a specific marker for stem cells.

Clinicopathologic significance of Sox2, CD44 and CD44v6 expression in intrahepatic cholangiocarcinoma

Embryonic stem cells (ESC) and cancer stem cells (CSC) have a capacity for self-renewal and differentiation into multiple cell lineages. Sox2 plays a critical role in ESC and has been shown to participate in carcinogenesis and tumor progression in many human cancers. CD44 and CD44v6 are putative CSC markers and their association with tumor progression, metastasis, and tumor relapse after treatment has been demonstrated. We evaluated the immunoexpression of Sox2, CD44, and CD44v6 in 85 cases of Intrahepatic cholangiocarcinomas (IHCC) and assessed their prognostic significance. Sox2 expression showed a significant association with lymph node metastasis (p = 0.025), T4 stage (p = 0.046), and worse overall survival (p = 0.047). Greater expression of Sox2 was observed in IHCC with poor differentiation, vascular invasion, and stage IV, without statistical significance (p > 0.05). CD44 expression showed an association with periductal infiltrative type (p = 0.034), poor differentiation (p = 0.012), and vascular invasion (p = 0.009). CD44v6 expression was evident in patients with stage IV (p = 0.019). These results demonstrated that Sox2 expression is associated with aggressive behavior and poor overall survival in IHCC.

β-Catenin, a Sox2 binding partner, regulates the DNA binding and transcriptional activity of Sox2 in breast cancer cells

Sox2, an embryonic stem cell marker, has been recently implicated in the pathogenesis of breast cancer (BC). Using liquid chromatography-mass spectrometry and co-immunoprecipitation, we identified β-catenin as a Sox2 binding partner in MCF7 cells. The interaction between Sox2 and β-catenin was substantially different between the two cell subsets separated based on their differential responsiveness to a Sox2 reporter. Specifically, while β-catenin binds to Sox2 in the nuclear fraction of cells showing reporter-responsiveness (i.e. RR cells), this interaction was not detectable in those that were reporter-unresponsive (i.e. RU cells). In RR but not in RU cells, siRNA knockdown of β-catenin significantly upregulated the Sox2 transcriptional activity, enhanced its DNA binding and increased the expression of its target genes. Correlating with these findings, while inhibition of β-catenin significantly downregulated the mammosphere formation efficiency in RU cells, this treatment paradoxically increased that of RR cells. To conclude, we identified that β-catenin is an important binding partner of Sox2 and a regulator of its transcriptional activity in a small subset of BC cells. The interaction between Sox2 and β-catenin provides a novel mechanism underlying the functional dichotomy of BC cells, which carries potential therapeutic implications.

SOX2 promotes dedifferentiation and imparts stem cell-like features to pancreatic cancer cells

SOX2 (Sex-determining region Y (SRY)-Box2) has important functions during embryonic development and is involved in cancer stem cell (CSC) maintenance, in which it impairs cell growth and tumorigenicity. However, the function of SOX2 in pancreatic cancer cells is unclear. The objective of this study was to analyze SOX2 expression in human pancreatic tumors and determine the role of SOX2 in pancreatic cancer cells regulating CSC properties. In this report, we show that SOX2 is not expressed in normal pancreatic acinar or ductal cells. However, ectopic expression of SOX2 is observed in 19.3% of human pancreatic tumors. SOX2 knockdown in pancreatic cancer cells results in cell growth inhibition via cell cycle arrest associated with p21(Cip1) and p27(Kip1) induction, whereas SOX2 overexpression promotes S-phase entry and cell proliferation associated with cyclin D3 induction. SOX2 expression is associated with increased levels of the pancreatic CSC markers ALDH1, ESA and CD44. Importantly, we show that SOX2 is enriched in the ESA(+)/CD44(+) CSC population from two different patient samples. Moreover, we show that SOX2 directly binds to the Snail, Slug and Twist promoters, leading to a loss of E-Cadherin and ZO-1 expression. Taken together, our findings show that SOX2 is aberrantly expressed in pancreatic cancer and contributes to cell proliferation and stemness/dedifferentiation through the regulation of a set of genes controlling G1/S transition and epithelial-to-mesenchymal transition (EMT) phenotype, suggesting that targeting SOX2-positive cancer cells could be a promising therapeutic strategy.

Molecular biomarkers in esophageal, gastric, and colorectal adenocarcinoma

Cancers of the esophagus, stomach and colon contribute to a major health burden worldwide and over 20% of all cancer deaths. Biomarkers that should indicate pathogenic process and are measureable in an objective manner for these tumors are rare and not established in the clinical setting. In general biomarkers can be very useful for cancer management as they can improve clinical decision-making regarding diagnosis, surveillance, and therapy. Biomarkers can be different types of molecular entities (such as DNA, RNA or proteins), which can be detected, in different tissues or body fluids. However, more important is the type of biomarker itself, which allows diagnostic, prognostic or predictive analyses for different clinical problems. This review aims to systematically summarize the recent findings of genetic and epigenetic markers for gastrointestinal tumors within the last decade. While many biomarkers seem to be very promising, especially if used as panels, further development is urgently needed to address practical considerations of biomarkers in cancer treatment.

Sex determining region Y-box 2 inhibits the proliferation of colorectal adenocarcinoma cells through the mTOR signaling pathway

Sex determining region Y-box 2 (SOX2), is a high mobility group box transcription factor involved in the maintenance of pluripotency and the self-renewal of embryonic and neuronal stem cells, which also plays differential roles in the cell proliferation of several tumors. However, its role in colorectal adenocarcinoma cell proliferation and the underlying mechanisms remain unclear. The mammalian target of rapamycin (mTOR) signaling pathway has recently emerged as an important regulator of cell proliferation in many types of cancer. In this study, we examined the effect of SOX2 on the proliferation of colorectal adenocarcinoma cells and evaluated the role of the mTOR pathway in this process. Our results indicated that the overexpression of SOX2 significantly inhibited the proliferation of colorectal adenocarcinoma cells. Of note, mechanistic investigations revealed that SOX2 inhibited the activation of the mTOR pathway in HT-29 cells. We then examined the effect of SOX2 on the cell cycle, and the results revealed that SOX2 downregulated cyclin D1 expression and induced G0/G1 arrest in the HT-29 cells. Moreover, we also analyzed the correlation between SOX2 expression and patient clinicopathological characteristics in colorectal adenocarcinoma tissues, as well as the level of phospho-S6 (S235/236), phospho-Akt (S473) and cyclin D1. The results revealed a significant negative correlation between SOX2 expression and tumor size and the levels of phospho-S6 (S235/236), phospho-Akt (S473) and cyclin D1. Taken together, to our knowledge, our findings suggest for the first time that SOX2 suppresses colorectal adenocarcinoma cell proliferation through the inhibition of the mTOR pathway.

Undifferentiated embryonic cell transcription factor-1 (UTF1) inhibits the growth of cervical cancer cells by transactivating p27Kip1

Undifferentiated embryonic cell transcription factor-1 (UTF1) is an important transcription factor during development, which plays critical roles in cell fate determination. However, its expression and function in somatic tissues remain unclear. Here, we investigated the expression pattern of the UTF1 in the human normal and cancerous lesions of cervix and found that UTF1 was downregulated in cervical carcinogenesis, which was related to the hypermethylation of UTF1 promoter. Exogenous expression of UTF1 resulted in the significant inhibition of cell proliferation in vitro and tumorigenesis in vivo through attenuating cell cycle arrest via increasing the level of p27 (Kip1) . Luciferase reporter assay indicated that the region containing an intact activating transcription factor site between nucleotides -517 and -388 of the p27 (Kip1) promoter was indispensable for its activation by UTF1. Chromatin immunoprecipitation analysis confirmed the physical interaction between UTF1 and the p27 (Kip1) promoter. Taken together, our findings reveal that UTF1 attenuates cell proliferation and is inactivated in cervical carcinogenesis through epigenetic modification, which strongly supports that UTF1 is a potential tumor suppressor.

Autophagy and cellular senescence mediated by Sox2 suppress malignancy of cancer cells

Autophagy is a critical cellular process required for maintaining cellular homeostasis in health and disease states, but the molecular mechanisms and impact of autophagy on cancer is not fully understood. Here, we found that Sox2, a key transcription factor in the regulation of the "stemness" of embryonic stem cells and induced-pluripotent stem cells, strongly induced autophagic phenomena, including intracellular vacuole formation and lysosomal activation in colon cancer cells. The activation occurred through Sox2-mediated ATG10 gene expression and resulted in the inhibition of cell proliferation and anchorage-independent colony growth ex vivo and tumor growth in vivo. Further, we found that Sox2-induced-autophagy enhanced cellular senescence by up-regulating tumor suppressors or senescence factors, including p16(INK4a), p21 and phosphorylated p53 (Ser15). Notably, knockdown of ATG10 in Sox2-expressing colon cancer cells restored cancer cell properties. Taken together, our results demonstrated that regulation of autophagy mediated by Sox2 is a mechanism-driven novel strategy to treat human colon cancers.

SOX2 overexpression correlates with poor prognosis in laryngeal squamous cell carcinoma

OBJECTIVE

The aim of present study was to investigate the expression of SOX2, a key transcription factor, in LSCC and to assess its prognostic significance.

METHODS

SOX2 expression of 161 LSCC tissues was detected by immunohistochemistry using a tissue microarray and statistically analyzed for its correlation with clinicopathological charateristics and patient outcome. In addition, SOX2 expression was also observed in 20 self-paired fresh LSCC tissues by western blot.

RESULTS

SOX2 was overexpressed in LSCC tissues as compared to the corresponding adjacent normal tissues. SOX2 expression was significantly associated with tumour T classification (p<0.001), clinical stage (p<0.001), lymph node metastasis (p=0.007) and recurrence (p=0.001). Univariate analysis revealed that patients with high SOX2 expression were significantly related to overall survival (p<0.001). Multivariate survival analysis further demonstrated that SOX2 expression was an independent prognostic factor for LSCC patients.

CONCLUSION

SOX2 may contribute to the malignant progression of laryngeal squamous cell carcinoma (LSCC), and present as a useful prognostic marker and a potential therapeutic target for LSCC patients.

The multiple roles for Sox2 in stem cell maintenance and tumorigenesis

The Sry-containing protein Sox2 initially was known to regulate the self-renewal of the mouse and human embryonic stem cells (ESCs). It is also important for the maintenance of stem cells in multiple adult tissues including the brain and trachea, and it is one of the key transcription factors for establishing induced pluripotent stem cells. Recently, overexpression and gene amplification of Sox2 have been associated with the development of squamous cell carcinoma in multiple tissues such as the lung and esophagus. These different roles for Sox2 involve a complicated regulatory networks consisting of microRNAs, kinases and signaling molecules. While the levels of Sox2 are modulated transcriptionally and translationally, post-translational modification is also important for the various functions of Sox2. In clinics, high levels of Sox2 are correlated with poor prognosis and increased proliferation of cancer stem cells. Therefore targeting Sox2 can be potentially explored for a new therapeutic avenue to treat cancers. This review will focus on the different roles for Sox2 in stem cell maintenance and its oncogenic roles in the context of signal transcription and microRNA regulation. We will also review the main upstream and downstream targets of Sox2, which can be potentially used as therapeutic measures to treat cancer with abnormal levels of Sox2.

Recent progress in the study of methylated tumor suppressor genes in gastric cancer

Gastric cancer is one of the most common malignancies and a leading cause of cancer mortality worldwide. The pathogenesis mechanisms of gastric cancer are still not fully clear. Inactivation of tumor suppressor genes and activation of oncogenes caused by genetic and epigenetic alterations are known to play significant roles in carcinogenesis. Accumulating evidence has shown that epigenetic silencing of the tumor suppressor genes, particularly caused by hypermethylation of CpG islands in promoters, is critical to carcinogenesis and metastasis. Here, we review the recent progress in the study of methylations of tumor suppressor genes involved in the pathogenesis of gastric cancer. We also briefly describe the mechanisms that induce tumor suppressor gene methylation and the status of translating these molecular mechanisms into clinical applications.

SOX1 functions as a tumor suppressor by antagonizing the WNT/β-catenin signaling pathway in hepatocellular carcinoma

Oncogenic activation of the Wnt/β-catenin signaling pathway is common in hepatocellular carcinoma (HCC). Our recent studies have demonstrated that SRY (sex determining region Y)-box 1 (SOX1) and secreted frizzled-related proteins are concomitantly promoter-hypermethylated, and this might lead to abnormal activation of the Wnt signaling pathway in HCC. SOX1 encodes a transcription factor involved in the regulation of embryonic development and cell fate determination. However, the expression and functional role of SOX1 in HCC remains unclear. In this study, we confirmed via quantitative methylation-specific polymerase chain reaction that SOX1 was frequently downregulated through promoter hypermethylation in HCC cells and tissues. Overexpression of SOX1 by a constitutive or inducible approach could suppress cell proliferation, colony formation, and invasion ability in HCC cell lines, as well as tumor growth in nonobese diabetic/severe combined immunodeficiency mice. Conversely, knockdown of SOX1 by withdrawal of doxycycline could partially restore cell proliferation and colony formation in HCC cells. We used a T cell factor (TCF)-responsive luciferase reporter assay and western blot analysis to prove that SOX1 could regulate TCF-responsive transcriptional activity and inhibit the expression of Wnt downstream genes. Furthermore, we used glutathione S-transferase pull-down, co-immunoprecipitation, and confocal microscopy to demonstrate that SOX1 could interact with β-catenin but not with the β-catenin/TCF complex. Moreover, restoration of the expression of SOX1 induces significant cellular senescence in Hep3B cells.

CONCLUSION

Our data show that a developmental gene, SOX1, may function as a tumor suppressor by interfering with Wnt/β-catenin signaling in the development of HCC.

The role of Sox genes in lung morphogenesis and cancer

The human lung consists of multiple cell types derived from early embryonic compartments. The morphogenesis of the lung, as well as the injury repair of the adult lung, is tightly controlled by a network of signaling pathways with key transcriptional factors. Lung cancer is the third most cancer-related death in the world, which may be developed due to the failure of regulating the signaling pathways. Sox (sex-determining region Y (Sry) box-containing) family transcriptional factors have emerged as potent modulators in embryonic development, stem cells maintenance, tissue homeostasis, and cancerogenesis in multiple processes. Recent studies demonstrated that the members of the Sox gene family played important roles in the development and maintenance of lung and development of lung cancer. In this context, we summarize our current understanding of the role of Sox family transcriptional factors in the morphogenesis of lung, their oncogenic potential in lung cancer, and their potential impact in the diagnosis, prognosis, and targeted therapy of lung cancer.

MiR-429 is an independent prognostic factor in colorectal cancer and exerts its anti-apoptotic function by targeting SOX2

Emerging evidence has demonstrated that microRNAs (miRNAs) can act as oncogenes or tumor suppressors to participate in cancer development. In this study, we found that miR-429 expression was up-regulated in human colorectal cancer (CRC) tissues, and the high miR-429 expression was significantly associated with tumor size, lymph node metastasis and poor prognosis. Functionally, miR-429 overexpression suppressed cell apoptosis by directly targeting SOX2 in HT-29 cells. Taken together, our data suggest for the first time that miR-429 could play an oncogenic role in the cellular processes of CRC and represent a novel prognostic biomarker for CRC.

Sox2 enhances the tumorigenicity and chemoresistance of cancer stem-like cells derived from gastric cancer

Gastric cancer stem-like cells (GCSCs) have been identified to possess the ability of self-renewal and tumor initiation. However, the mechanisms involved remain largely unknown. Here, we isolated and characterized the GCSCs by side population (SP) sorting procedure and cultured sphere cells (SC) from human gastric cancer cell lines SGC-7901, BGC-823, MGC-803, HGC-27 and MKN-28. The sorting and culture assay revealed that SP cells proliferated in an asymmetric division manner. In addition, SP cells exhibited a higher potential of spheroid colony formation and greater drug resistance than non-SP cells (NSP). Moreover, the SC were found with enhanced capabilities of drug resistance in vitro and tumorigenicity in vivo. Sox2 mRNA and protein was highly and significantly overexpressed in the SP cells and SC. Importantly, downregulation of Sox2 with siRNA obviously reduced spheroid colony formation and doxorubicin efflux, as well as increased apoptosis rate in sphere cells in vitro and suppressed tumorigenicity in vivo. These results suggest that both SP cells and cultured SC enrich with GCSCs and that Sox2 plays a pivotal role in sustaining stem cell properties and might be a potential target for gastric cancer therapy.

Small molecule antibody targeting HLA class I inhibits myeloma cancer stem cells by repressing pluripotency-associated transcription factors

Cancer stem cells have been proposed to be responsible for tumorigenesis and recurrence in various neoplastic diseases, including multiple myeloma (MM). We have previously reported that MM cells specifically express HLA class I at high levels and that single-chain Fv diabody against this molecule markedly induces MM cell death. Here we investigated the effect of a new diabody (C3B3) on cancer stem cell-like side population (SP) cells. SP fraction of MM cells highly expressed ABCG2 and exhibited resistance to chemotherapeutic agents; however, C3B3 induced cytotoxicity in both SP cells and main population (MP) cells to a similar extent. Moreover, C3B3 suppressed colony formation and tumorigenesis of SP cells in vitro and in vivo. Crosslinking of HLA class I by C3B3 mediated disruption of lipid rafts and actin aggregation, which led to inhibition of gene expression of β-catenin and pluripotency-associated transcription factors such as Sox2, Oct3/4 and Nanog. Conversely, knockdown of Sox2 and Oct3/4 mRNA reduced the proportion of SP cells, suggesting that these factors are essential in maintenance of SP fraction in MM cells. Thus, our findings reveal that immunotherapeutic approach by engineered antibodies can overcome drug resistance, and provide a new basis for development of cancer stem cell-targeted therapy.

Embryonic signature in breast cancers; Pluripotency roots of cancer stem cells

Drug discovery programs for preclinical oncology typically select compounds which have a predilection for inducing cytotoxic effects in cancer cell lines and subsequently, for inhibiting the growth of the transplanted cancer cells in vivo (Winquist et al., 2010). Unfortunately, the cytotoxic effect in vitro and inhibition of tumor growth in animal models are not the end story for curing cancer in preclinical models. The reason behind that is the exciting of small sub type of cells that are relatively resistance to therapy and able to repopulate in vivo, called cancer stem cells (CSCs). O leis et al. recently reported that the pluripotency gene Sox2 but not Oct4 or Nanog is expressed in early stage of breast tumor. Furthermore, the authors demonstrated that Sox2 downregulation, inhibited mammosphere formation and delayed tumor formation in xenograft tumor initiation models (Leis et al., 2012). In this review, we will shed the light on the importance of Sox2 in breast and other tissue tumorigenesis and associated aggressiveness.

A Prominin-1-Rich Pediatric Glioblastoma: Biologic Behavior Is Determined by Oxygen Tension-Modulated CD133 Expression but Not Accompanied by Underlying Molecular Profiles

Few studies on the biologic and molecular properties of pediatric glioblastoma have been performed. Until now, differential genomic analysis of CD133(+)ve and CD133(-)ve fractions has not been described in pediatric glioma. We hypothesize not only that the presence of CD133 could be the source of tumor resistance but also that maintenance of this molecule by hypoxia dictates cellular and molecular behavior. From a series of human glioblastoma biopsies investigated, only one, IN699 (from a pediatric glioblastoma), generated greater than 4% of the total cell volume as CD133(+)ve cells. Using this pediatric glioblastoma, containing unprecedented high levels of the putative brain tumor stem cell marker CD133, as a study model, we report biologic and molecular characteristics of the parent culture and of CD133(+)ve and CD133(-)ve populations derived therefrom under atmospheric and hypoxic culture conditions. Immunocytochemistry and flow cytometry were performed with antigenic markers known to characterize neural stem cells and associated glioma behavior. Behavioral analysis was carried out using proliferation, adhesion, migration, and invasion assays. Cell cycle analysis and array comparative genomic hybridization were used to assess copy number profiles for parental cells and CD133(+)ve and CD133(-)ve fractions, respectively. With regard to invasion and proliferation, CD133(+)ve and CD133(-)ve fractions were inversely proportional, with a significant increase in invasive propensity within the CD133(-)ve cells (P < .005) and a significant increase in proliferation within CD133(+)ve cells (P < .005). Our observations indicate identical genomic imbalances between CD133(+)ve and CD133(-)ve fractions. Furthermore, our research documents a direct link between decreasing oxygen tension and CD133 expression.

Targeted silencing of the oncogenic transcription factor SOX2 in breast cancer

The transcription factor (TF) SOX2 is essential for the maintenance of pluripotency and self-renewal in embryonic stem cells. In addition to its normal stem cell function, SOX2 over-expression is associated with cancer development. The ability to selectively target this and other oncogenic TFs in cells, however, remains a significant challenge due to the ‘undruggable’ characteristics of these molecules. Here, we employ a zinc finger (ZF)-based artificial TF (ATF) approach to selectively suppress SOX2 gene expression in cancer cells. We engineered four different proteins each composed of 6ZF arrays designed to bind 18 bp sites in the SOX2 promoter and enhancer region, which controls SOX2 methylation. The 6ZF domains were linked to the Kruppel Associated Box (SKD) repressor domain. Three engineered proteins were able to bind their endogenous target sites and effectively suppress SOX2 expression (up to 95% repression efficiencies) in breast cancer cells. Targeted down-regulation of SOX2 expression resulted in decreased tumor cell proliferation and colony formation in these cells. Furthermore, induced expression of an ATF in a mouse model inhibited breast cancer cell growth. Collectively, these findings demonstrate the effectiveness and therapeutic potential of engineered ATFs to mediate potent and long-lasting down-regulation of oncogenic TF expression in cancer cells.

Sex-determining region Y-box 2 expression predicts poor prognosis in human ovarian carcinoma

Sex-determining region Y-box 2 is proposed to be a key transcription factor in embryonic stem cells. The known roles of sex-determining region Y-box 2 in development and cell differentiation suggest that it is relevant to the aberrant growth of tumor cells. Thus, sex-determining region Y-box 2 may play an important role in tumor progression. However, its clinical significance in human ovarian carcinoma has been uncertain until recently. The aim of the present study was to clarify the clinical role of sex-determining region Y-box 2 expression in ovarian carcinoma. Immunohistochemical staining of 540 human ovarian carcinoma samples for sex-determining region Y-box 2 was performed using tissue microarray. The associations among sex-determining region Y-box 2 expression and clinical factors (diagnosis, tumor grade, International Federation of Gynecology and Obstetrics stage, and response to chemotherapy), overall survival, and disease-free survival were analyzed. We observed sex-determining region Y-box 2 expression in 15% of the ovarian carcinoma samples. Use of the Fisher exact test suggested that sex-determining region Y-box 2 expression was associated with high-grade carcinoma (P = .009), especially high-grade serous carcinoma (P = .048); International Federation of Gynecology and Obstetrics stage (II-IV; P = .005); and malignant mixed müllerian tumors (P = .048). Sex-determining region Y-box 2 expression was also associated with decreased disease-free survival durations (P = .035; log-rank test). Our results showed that sex-determining region Y-box 2 expression may be a potential marker related to tumor recurrence, as implicated by its role in cancer stem cells.

CpG island hypermethylation in gastric carcinoma and its premalignant lesions

Gastric cancers arise through a multistep process characterized by the progressive accumulation of molecular alterations in which genetic and epigenetic mechanisms have been implicated. Gastric cancer is one of the human malignancies in which aberrant promoter CpG island hypermethylation is frequently found. Helicobacter pylori and Epstein-Barr virus, which are known carcinogens for gastric cancer, are closely associated with enhanced hypermethylation of CpG island loci in gastric non-neoplastic epithelial cells and cancer cells, respectively. Aberrant CpG island hypermethylation occurs early in the multistep cascade of gastric carcinogenesis and tends to increase with the step-wise progression of the lesion. Approximately 400 genes that are actively expressed in normal gastric epithelial cells are estimated to be inactivated in gastric cancers as a result of promoter CpG island hypermethylation. In this review, a variety of information is summarized regarding CpG island hypermethylation in gastric cancer.

Parent-of-origin effects in SOX2 anophthalmia syndrome

PURPOSE

Sex determining region Y (SRY)-box 2 (SOX2) anophthalmia syndrome is an autosomal dominant disorder manifesting as severe developmental eye malformations associated with brain, esophageal, genital, and kidney abnormalities. The syndrome is usually caused by de novo mutations or deletions in the transcription factor SOX2. To investigate any potential parental susceptibility factors, we set out to determine the parent of origin of the mutations or deletions, and following this, to determine if birth order or parental age were significant factors, as well as whether mutation susceptibility was related to any sequence variants in cis with the mutant allele.

METHODS

We analyzed 23 cases of de novo disease to determine the parental origin of SOX2 mutations and deletions using informative single nucleotide polymorphisms and a molecular haplotyping approach. We examined parental ages for SOX2 mutation and deletion cases, compared these with the general population, and adjusted for birth order.

RESULTS

Although the majority of subjects had mutations or deletions that arose in the paternal germline (5/7 mutation and 5/8 deletion cases), there was no significant paternal bias for new mutations (binomial test, p=0.16) or deletions (binomial test, p=0.22). For both mutation and deletion cases, there was no significant association between any single nucleotide polymorphism allele and the mutant chromosome (p>0.05). Parents of the subjects with mutations were on average older at the birth of the affected child than the general population by 3.8 years (p=0.05) for mothers and 3.3 years (p=0.66) for fathers. Parents of the subjects with deletions were on average younger than the general population by 3.0 years (p=0.17) for mothers and 2.1 years (p=0.19) for fathers. Combining these data, the difference in pattern of parental age between the subjects with deletions and mutations was evident, with a difference of 6.5 years for mothers (p=0.05) and 5.0 years for fathers (p=0.22), with the mothers and fathers of subjects with mutations being older than the mothers and fathers of subjects with deletions. We observed that 14 of the 23 (61%) affected children were the first-born child to their mother, with 10/15 of the mutation cases (66%) and 4/8 deletion cases (50%) being first born. This is in comparison to 35% of births with isolated congenital anomalies overall who are first born (p=0.008).

CONCLUSIONS

Sporadic SOX2 mutations and deletions arose in both the male and female germlines. In keeping with several genetic disorders, we found that SOX2 mutations were associated with older parental age and the difference was statistically significant for mothers (p=0.05), whereas, although not statistically significant, SOX2 deletion cases had younger parents. With the current sample size, there was no evidence that sequence variants in cis surrounding SOX2 confer susceptibility to either mutations or deletions.

SOX2-RNAi attenuates S-phase entry and induces RhoA-dependent switch to protease-independent amoeboid migration in human glioma cells

BACKGROUND

SOX2, a high mobility group (HMG)-box containing transcription factor, is a key regulator during development of the nervous system and a persistent marker of neural stem cells. Recent studies suggested a role of SOX2 in tumor progression. In our previous work we detected SOX2 in glioma cells and glioblastoma specimens. Herein, we aim to explore the role of SOX2 for glioma malignancy in particular its role in cell proliferation and migration.

METHODS

Retroviral shRNA-vectors were utilized to stably knockdown SOX2 in U343-MG and U373-MG cells. The resulting phenotype was investigated by Western blot, migration/invasion assays, RhoA G-LISA, time lapse video imaging, and orthotopic xenograft experiments.

RESULTS

SOX2 depletion results in pleiotropic effects including attenuated cell proliferation caused by decreased levels of cyclinD1. Also an increased TCF/LEF-signaling and concomitant decrease in Oct4 and Nestin expression was noted. Furthermore, down-regulation of focal adhesion kinase (FAK) signaling and of downstream proteins such as HEF1/NEDD9, matrix metalloproteinases pro-MMP-1 and -2 impaired invasive proteolysis-dependent migration. Yet, cells with knockdown of SOX2 switched to a RhoA-dependent amoeboid-like migration mode which could be blocked by the ROCK inhibitor Y27632 downstream of RhoA-signaling. Orthotopic xenograft experiments revealed a higher tumorigenicity of U343-MG glioma cells transduced with shRNA targeting SOX2 which was characterized by increased dissemination of glioma cells.

CONCLUSION

Our findings suggest that SOX2 plays a role in the maintenance of a less differentiated glioma cell phenotype. In addition, the results indicate a critical role of SOX2 in adhesion and migration of malignant gliomas.

Genetic and epigenetic modifications of Sox2 contribute to the invasive phenotype of malignant gliomas

We undertook this study to understand how the transcription factor Sox2 contributes to the malignant phenotype of glioblastoma multiforme (GBM), the most aggressive primary brain tumor. We initially looked for unbalanced genomic rearrangements in the Sox2 locus in 42 GBM samples and found that Sox2 was amplified in 11.5% and overexpressed in all the samples. These results prompted us to further investigate the mechanisms involved in Sox2 overexpression in GBM. We analyzed the methylation status of the Sox2 promoter because high CpG density promoters are associated with key developmental genes. The Sox2 promoter presented a CpG island that was hypomethylated in all the patient samples when compared to normal cell lines. Treatment of Sox2-negative glioma cell lines with 5-azacitidine resulted in the re-expression of Sox2 and in a change in the methylation status of the Sox2 promoter. We further confirmed these results by analyzing data from GBM cases generated by The Cancer Genome Atlas project. We observed Sox2 overexpression (86%; N = 414), Sox2 gene amplification (8.5%; N = 492), and Sox 2 promoter hypomethylation (100%; N = 258), suggesting the relevance of this factor in the malignant phenotype of GBMs. To further explore the role of Sox2, we performed in vitro analysis with brain tumor stem cells (BTSCs) and established glioma cell lines. Downmodulation of Sox2 in BTSCs resulted in the loss of their self-renewal properties. Surprisingly, ectopic expression of Sox2 in established glioma cells was not sufficient to support self-renewal, suggesting that additional factors are required. Furthermore, we observed that ectopic Sox2 expression was sufficient to induce invasion and migration of glioma cells, and knockdown experiments demonstrated that Sox2 was essential for maintaining these properties. Altogether, our data underscore the importance of a pleiotropic role of Sox2 and suggest that it could be used as a therapeutic target in GBM.

SOX2 haploinsufficiency is associated with slow progressing hypothalamo-pituitary tumours

SOX2 is an early developmental transcription factor and marker of stem cells that has recently been implicated in the development of the pituitary gland. Heterozygous SOX2 mutations have been described in patients with hypopituitarism and severe ocular abnormalities. In the majority of published cases, the pituitary gland is either small or normal in size. Here, we report two unrelated patients with SOX2 haploinsufficiency (a heterozygous gene deletion and a novel c.143TC>AA/p.F48X mutation) who developed nonprogressive pituitary tumors of early onset, suggesting a congenital etiology. The truncating mutation resulted in significant loss of function and impaired nuclear localization of the mutant protein, in addition to a failure to repress β-catenin transcriptional activity in vitro. This is the first indication that SOX2 haploinsufficiency is implicated in the generation of pituitary tumors with distinct clinical characteristics, possibly mediated via its effects on the Wnt signaling pathway.

Establishment of a choriocarcinoma model from immortalized normal extravillous trophoblast cells transduced with HRASV12

Gestational choriocarcinoma is a malignant trophoblastic tumor. The development of novel molecular-targeted therapies is needed to reduce the toxicity of current multiagent chemotherapy and to treat successfully the chemoresistant cases. The molecular mechanisms underlying choriocarcinoma tumorigenesis remain uncharacterized, however, and appropriate choriocarcinoma animal models have not yet been developed. In this study, we established a choriocarcinoma model by inoculating mice with induced-choriocarcinoma cell-1 (iC³-1) cells, generated from HTR8/SVneo human trophoblastic cells retrovirally transduced with activated H-RAS (HRASV12). The iC³-1 cells exhibited constitutive activation of the mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) pathways and developed into lethal tumors in all inoculated mice. Histopathological analysis revealed that the tumors consisted of two distinct types of cells, reminiscent of syncytiotrophoblasts and cytotrophoblasts, as seen in the human choriocarcinoma. The tumors expressed HLA-G and cytokeratin (trophoblast markers) and hCG (a choriocarcinoma marker). Comparative analysis of gene expression profiles between iC³-1 cells and parental HTR8/SVneo cells revealed that iC³-1 cells expressed matrix metalloproteinases, epithelial-mesenchymal transition-related genes, and SOX3 at higher levels than parental trophoblastic cells. Administration of SOX3-specific short-hairpin RNA decreased SOX3 expression and attenuated the tumorigenic activity of iC³-1 cells, suggesting that SOX3 overexpression might be critically involved in the pathogenesis of choriocarcinoma. Our murine model represents a potent new tool for studying the pathogenesis and treatment of choriocarcinoma.

FoxM1 in tumorigenicity of the neuroblastoma cells and renewal of the neural progenitors

Malignant neuroblastomas contain stem-like cells. These tumors also overexpress the Forkhead box transcription factor FoxM1. In this study, we investigated the roles of FoxM1 in the tumorigenicity of neuroblastoma. We showed that depletion of FoxM1 inhibits anchorage-independent growth and tumorigenicity in mouse xenografts. Moreover, knockdown of FoxM1 induces differentiation in neuroblastoma cells, suggesting that FoxM1 plays a role in the maintenance of the undifferentiated progenitor population. We showed that inhibition of FoxM1 in malignant neuroblastoma cells leads to the downregulation of the pluripotency genes sex determining region Y box 2 (Sox2) and Bmi1. We provided evidence that FoxM1 directly activates expression of Sox2 in neuroblastoma cells. By using a conditional deletion system and neurosphere cultures, we showed that FoxM1 is important for expression of Sox2 and Bmi1 in the mouse neural stem/progenitor cells and is critical for its self-renewal. Together, our observations suggested that FoxM1 plays an important role in the tumorigenicity of the aggressive neuroblastoma cells through maintenance of the undifferentiated state.