Role Of SOX2 Research Articles

SOX6 represses tumor growth of clear cell renal cell carcinoma by HMG domain-dependent regulation of Wnt/β-catenin signaling.

Sex-determining region Y box (SOXs) are expressed in various cells and control cell fate and differentiation in a multitude of physiologic processes. SOX6, a main representative of SOXs, is involved in the regulation of carcinogenesis in various human malignancies. However, the role of SOX6 in clear cell renal cell carcinoma (ccRCC) remains unclear. In this study, SOX6 expression in ccRCC and its clinical significance were investigated. In vitro and in vivo assays were used to explore the tumor-related function and the underlying molecular mechanism of SOX6 in ccRCC. We confirmed that SOX6 was frequently downregulated in ccRCC tissues and cell lines. Besides, downregulation of SOX6 was significantly associated with larger tumor sizes, advanced tumor stage, higher Fuhrman grades, and its expression could act as an independent prognostic factor for ccRCC (hazards ratio = 0.590, P = .026). Gain/loss-of-function experiments demonstrated that SOX6 could remarkably inhibit tumor cell growth and foci formation in vitro and xenograft tumorigenesis in vivo, respectively. Mechanistically, SOX6 could influence cell cycle by regulating the G1/the S phase transition and had an inhibitory effect on Wnt/β-catenin signaling as well as its target genes, c-Myc and cyclin D1. Interesting, the tumor-suppressive function of SOX6 was proved to be dependent on its specific high-mobility-group (HMG) domain. In general, our findings indicated that SOX6 was a novel tumor suppressor and prognostic biomarker in ccRCC. SOX6 could inhibit tumor growth by negatively regulating the Wnt/β-catenin signaling pathway in an HMG domain-dependent manner in ccRCC, which might provide a novel therapeutic approach for ccRCC.

SOX2-Upregulated microRNA-30e Promotes Cell Invasion in Esophageal Cancer via USP4/SMAD4/CK2 Axis

Background: Both SOX2 and microRNA-30e (miR-30e) were reported to be involved in esophageal cancer (EC) progression. However, whether there is correlation between SOX2 and miR-30e in EC cells remains undiscovered. Herein, this study was intended to explore the correlation between SOX2 and miR-30e in EC and the effect of this correlation on EC cell invasion. Methods: Following collection of EC tissues and cells, miR-30e, SOX2, miR-30e, USP4, SMAD4, and CK2 expression was determined by RT-qPCR, western blot analysis and immunohistochemistry. Gain- and loss-of-function approaches were conducted in screened cell lines, followed by determination of cell proliferation, migration, invasion, and expression of epithelial-mesenchymal transition (EMT)-related genes. The relationship among miR-30e, USP4, SMAD4 and CK2 was assessed by dual-luciferase reporter assay, in vitro protein purification, immunoprecipitation, and ubiquitination experiments, and ChIP assay. The role of SOX2 and CK2 in EC in vivo was evaluated by tumor xenograft in nude mice. Results: EC tissues and cells contained high expression of SOX2, miR-30e, and CK2 as well as low expression of USP4 and SMAD4. miR-30e was upregulated by SOX2, and specifically targeted USP4. Additionally, USP4 induced the deubiquitination of SMAD4 to upregulate SMAD4. SMAD4 was enriched in CK2 promoter region and inhibited CK2 expression. Silencing of SMAD4 or USP4 or upregulation of SOX2, miR-30e or CK2 triggered enhancement in EC cell proliferation, migration, invasion, and EMT in vitro, and promotion of tumor growth and lung metastasis in vivo. Conclusion: Taken together, our work reveals a novel SOX2-mediated regulatory axis that plays critical roles in the invasiveness of EC cells. Funding Statement: This work was supported by Youth Foundation of the National Natural Science Foundation of China (No. 81702971), Key Scientific Research Projects of Colleges and Universities of Henan Province (No. 18A320054), Science and Technology Research Projects of Henan Province (No. 182102310116) and Youth Talent Lifting Projects of Henan Province (No. 2020HYTP050) Declaration of Interests: The authors declare that they have no competing interests. Ethics Approval Statement: The ethics committee of the First Affiliated Hospital of Zhengzhou University provided Ethical Approval for the experiments involved human beings in this study which were guided by the intentions of the Declaration of Helsinki. Ethical agreements were obtained from the donors or their relatives by written informed consent. The experiments involved animals were implemented in accordance with the principles embodied in the National Institutes of Health Guide for the Care and Use of Laboratory. Efforts were made to avoid all unnecessary distress to the animals.

SOX2 Expression and Transcriptional Activity Identifies a Subpopulation of Cancer Stem Cells in Sarcoma with Prognostic Implications.

Stemness in sarcomas is coordinated by the expression of pluripotency factors, like SOX2, in cancer stem cells (CSC). The role of SOX2 in tumor initiation and progression has been well characterized in osteosarcoma. However, the pro-tumorigenic features of SOX2 have been scarcely investigated in other sarcoma subtypes. Here, we show that SOX2 depletion dramatically reduced the ability of undifferentiated pleomorphic sarcoma (UPS) cells to form tumorspheres and to initiate tumor growth. Conversely, SOX2 overexpression resulted in increased in vivo tumorigenicity. Moreover, using a reporter system (SORE6) which allows to monitor viable cells expressing SOX2 and/or OCT4, we found that SORE6+ cells were significantly more tumorigenic than the SORE6- subpopulation. In agreement with this findings, SOX2 expression in sarcoma patients was associated to tumor grade, differentiation, invasive potential and lower patient survival. Finally, we studied the effect of a panel of anti-tumor drugs on the SORE6+ cells of the UPS model and patient-derived chondrosarcoma lines. We found that the mithramycin analogue EC-8042 was the most efficient in reducing SORE6+ cells in vitro and in vivo. Overall, this study demonstrates that SOX2 is a pro-tumorigenic factor with prognostic potential in sarcoma. Moreover, SORE6 transcriptional activity is a bona fide CSC marker in sarcoma and constitutes an excellent biomarker for evaluating the efficacy of anti-tumor treatments on CSC subpopulations.

SOX2 Expression and Transcriptional Activity Identifies a Subpopulation of Cancer Stem Cells in Sarcoma with Prognostic Implications

Background: Stemness in sarcomas is coordinated by the expression of pluripotency factors, like SOX2, in cancer stem cell (CSC) subpopulations. The role of SOX2 in tumor initiation and progression has been well characterized in osteosarcoma. However, the pro-tumorigenic features of SOX2 have been scarcely investigated in other sarcoma subtypes. Methods: shRNA and cDNA lentiviral constructions were used to deplete and overexpress SOX2 in a model of undifferentiated pleomorphic sarcoma (UPS). In addition, we introduced a reporter system (SORE6) which allows to detect and isolate viable cells expressing SOX2 and/or OCT4 in the UPS model and patient-derived chondrosarcoma lines. Functional CSC characterization included tumorsphere formation, in vivo xenograft growth assays, and pharmacologic testing of the effects of doxorubicin, placlitaxel, trabectedin or the mithramycin analogue EC8042. Immunohistochemical analysis of a cohort of 88 formalin-fixed and paraffin-embedded sarcoma samples was performed to correlate SOX2 expression with clinical parameters. Findings: SOX2 depletion dramatically reduced the ability of sarcoma cells to form tumorspheres and to initiate tumor growth in vivo. Conversely, SOX2 overexpression resulted in increased in vivo tumorigenicity. In sarcoma patients, SOX2 expression was associated to advanced disease stages, aggressive phenotypes and lower survival. Finally, SORE6+ cells were significantly more tumorigenic than the SORE6- population and EC-8042 effectively targeted SORE6+ cells in vitro and in vivo. Interpretation: SOX2 is a pro-tumorigenic factor with prognostic potential in sarcoma. Moreover, SORE6 transcriptional activity is a bona fide CSC marker in sarcoma and constitutes an excellent biomarker for evaluating the efficacy of anti-tumor treatments on CSC subpopulations. Funding Statement: This work was supported by the Agencia Estatal de Investigacion (AEI) [MINECO/Fondo Europeo de Desarrollo Regional (FEDER) (SAF-2016-75286-R to R.R.), ISC III/FEDER (Miguel Servet Program CPII16/00049 to R.R., Sara Borrell Program CD16/00103 to S.T.M. and PI16/00280 and PI19/00560 to J.M.G-P) and Consorcio CIBERONC CB16/12/00390)] and the Plan de Ciencia Tecnologia e Innovacion del Principado de Asturias/FEDER (IDI/2018/155) to J.P.R. PharmaMar and EntreChem also provided support. Finally, the authors acknowledge the Principado de Asturias BioBank (PT17/0015/0023), financed jointly by Servicio de Salud del Principado de Asturias, Instituto de Salud Carlos III and Fundacion Bancaria Cajastur and integrated in the Spanish National Biobanks Network, for its collaboration. Declaration of Interests: The authors declare they have no competing interests. Ethics Approval Statement: All experimental protocols have been performed in accordance with institutional review board guidelines and were approved by the Institutional Ethics Committee of the Principado de Asturias. All samples from human origin were obtained upon signed informed consent. All experimental protocols were carried out in accordance with the institutional guidelines of the University of Oviedo and were approved by the Animal Research Ethical Committee of the University of Oviedo prior to the study.

Connexin43 peptide, TAT-Cx43266-283, selectively targets glioma cells, impairs malignant growth, and enhances survival in mouse models in vivo.

BackgroundMalignant gliomas are the most frequent primary brain tumors and remain among the most incurable cancers. Although the role of the gap junction protein, connexin43 (Cx43), has been deeply investigated in malignant gliomas, no compounds have been reported with the ability to recapitulate the tumor suppressor properties of this protein in in vivo glioma models.MethodsTAT-Cx43266–283 a cell-penetrating peptide which mimics the effect of Cx43 on c-Src inhibition, was studied in orthotopic immunocompetent and immunosuppressed models of glioma. The effects of this peptide in brain cells were also analyzed.ResultsWhile glioma stem cell malignant features were strongly affected by TAT-Cx43266–283, these properties were not significantly modified in neurons and astrocytes. Intraperitoneally administered TAT-Cx43266–283 decreased the invasion of intracranial tumors generated by GL261 mouse glioma cells in immunocompetent mice. When human glioma stem cells were intracranially injected with TAT-Cx43266–283 into immunodeficient mice, there was reduced expression of the stemness markers nestin and Sox2 in human glioma cells at 7 days post-implantation. Consistent with the role of Sox2 as a transcription factor required for tumorigenicity, TAT-Cx43266–283 reduced the number and stemness of human glioma cells at 30 days post-implantation. Furthermore, TAT-Cx43266–283 enhanced the survival of immunocompetent mice bearing gliomas derived from murine glioma stem cells.ConclusionTAT-Cx43266–283 reduces the growth, invasion, and progression of malignant gliomas and enhances the survival of glioma-bearing mice without exerting toxicity in endogenous brain cells, which suggests that this peptide could be considered as a new clinical therapy for high-grade gliomas.

Sox2 maintains epithelial cell proliferation in the successional dental lamina.

ObjectivesThe successional dental lamina is the distinctive structure on the lingual side of the vertebrate tooth germ. The aim of this study was to investigate the relationship among Sox2, Claudin10 and laminin5 and the role of Sox2 in successional dental lamina proliferation during vertebrate tooth development.Materials and MethodsTo understand the successional dental lamina, two types of successional tooth formation, that in geckos (with multiple rounds of tooth generation) and that in mice (with only one round of tooth generation), were analysed.ResultsUnique coexpression patterns of Sox2 and Claudin10 expression were compared in the successional dental lamina from the cap stage to the late bell stage in the mouse tooth germ and in juvenile gecko teeth to support continuous tooth replacement. Furthermore, Laminin5 expression was shown in the cap stage and decreased after the bell stage. Upon comparing the epithelial cell cycles and cell proliferation in successional dental lamina regions between mouse and gecko molars using BrdU and IdU staining and pulse‐chase methods, distinctive patterns of continuous expression were revealed. Moreover, Sox2 overexpression with a lentiviral system resulted in hyperplastic dental epithelium in mouse molars.ConclusionsOur findings indicate that the regulation of Sox2 in dental lamina proliferation is fundamental to the successional dental lamina in both species.

The effect of SOX9 on islet β cells in high glucose environment through regulation of ERK/P38 signaling pathway.

Islet beta cells are involved in insulin secretion. SRY-related high mobility group 9 (SX-S9) is involved in the progression of various diseases, but the role of SOX9 in islet β cells remains unclear. The islet β cell MIN6 cells were cultured in vitro and randomly divided into control group, high glucose group, and SOX9 siRNA group followed by analysis of SOX9 mRNA and protein expression by real-time PCR and Western blot, respectively, cell proliferation by MTT assay, cell apoptosis by flow cytometry, secretion of inflammatory factors TNF-α and IL-2 by ELISA, insulin secretion levels by spectrophotometer, myeloperoxidase (MPO), and superoxide dismutase (SOD) activities, as well as ERK/P38 signaling protein expression by Western blot. Under high glucose environment, SOX9 mRNA and protein expression were significantly increased, MIN6 cell proliferation was inhibited, apoptosis rate and secretion of TNF-α and IL-2 were increased, along with decreased insulin secretion, increased MPO content, decreased SOD activity and phosphorylation of ERK/P38, compared with control group (p < 0.05). However, transfection of SOX9 siRNA reduced SOX9 expression, promoted proliferation of MIN6 cells, decreased apoptotic rate and secretion of TNF-α and IL-2, increased insulin secretion, decreased MPO content, increased SOD and ERK/P38 protein phosphorylation. Compared with high glucose group, the differences were statistically significant (p < 0.05). The expression of SOX9 is increased under high glucose environment. Down-regulation of SOX9 expression can inhibit islet cell apoptosis, oxidative stress and inflammation, and promote islet cell proliferation and insulin secretion by regulating ERK/P38 signaling pathway.

NF-YA transcriptionally activates the expression of SOX2 in cervical cancer stem cells

Roles for SOX2 have been extensively studied in several types of cancer, including colorectal cancer, glioblastoma and breast cancer, with particular emphasis placed on the roles of SOX2 in cancer stem cell. Our previous study identified SOX2 as a marker in cervical cancer stem cells driven by a full promoter element of SOX2 EGFP reporter. Here, dual-luciferase reporter and mutagenesis analyses were employed, identifying key cis-elements in the SOX2 promoter, including binding sites for SOX2, OCT4 and NF-YA factors in SOX2 promoter. Mutagenesis analysis provided additional evidence to show that one high affinity-binding domain CCAAT box was precisely recognized and bound by the transcription factor NF-YA. Furthermore, overexpression of NF-YA in primitive cervical cancer cells SiHa and C33A significantly activated the transcription and the protein expression of SOX2. Collectively, our data identified NF-YA box CCAAT as a key cis-element in the SOX2 promoter, suggesting that NF-YA is a potent cellular regulator in the maintenance of SOX2-positive cervical cancer stem cell by specific transcriptional activation of SOX2.

SOX4: Epigenetic regulation and role in tumorigenesis.

Sex-determining region Y-related (SRY) high-mobility group box 4 (SOX4) is a member of the group C subfamily of SOX transcription factors and promotes tumorigenesis by endowing cancer cells with survival, migratory, and invasive capacities. Emerging evidence has highlighted an unequivocal role for this transcription factor in mediating various signaling pathways involved in tumorigenesis, epithelial-to-mesenchymal transition (EMT), and tumor progression. During the last decade, numerous studies have highlighted the epigenetic interplay between SOX4-targeting microRNAs (miRNAs), long noncoding RNAs (lncRNAs) and SOX4 and the subsequent modulation of tumorigenesis, invasion and metastasis. In this review, we summarize the current state of knowledge about the role of SOX4 in cancer development and progression, the epigenetic regulation of SOX4, and the potential utilization of SOX4 as a diagnostic and prognostic biomarker and its depletion as a therapeutic target.

Abstract 785: The inhibitory effect of compound ChlA-F onhuman bladder cancer cell invasion can be attributed to its blockage of SOX2 protein

Abstract Sex-determining region Y-box 2 (SOX2), a well-known stemness biomarker, is highly expressed in a variety of cancers, including human highly invasive bladder cancer (BC). However, the role of SOX2 may vary in different kinds of malignancy. In the present study, we discovered that ChlA-F, a novel conformation derivative of isolate Cheliensisin A (Chel A), remarkably inhibits the invasive ability of human invasive BC cells through downregulation of SOX2 protein expression. We found that ChlA-F treatment dramatically decreases SOX2 protein expression in human high-grade invasive BC cells. Ectopic expression of SOX2 reversed ChlA-F inhibition of cell invasion ability in human bladder cancer cells, suggesting that SOX2 is a major target of ChlA-F during its inhibition of human BC invasion. Mechanistic studies revealed that SOX2 is downregulated by ChlA-F at both the protein degradation and protein translation levels. Further studies revealed that ChlA-F treatment induces HuR protein expression and that the increased HuR interacts with USP8 mRNA, resulting in elevation of USP8 mRNA stability and protein expression. Elevated USP8 subsequently acts as an E3 ligase to promote SOX2 ubiquitination and protein degradation. We also found that ChlA-F treatment substantially increases c-Jun phosphorylation at Ser63 and Ser73, initiating miR-200c transcription. The increased miR-200c directly binds to the 3’-UTR of SOX2 mRNA to suppress SOX2 protein translation. These results present novel mechanistic insight into understanding SOX2 inhibition upon ChlA-F treatment and provide important information for further exploration of ChlA-F as a new therapeutic compound for the treatment of highly invasive/metastatic human BC patients. Citation Format: Xiaohui Hua, Jiheng Xu, Chuanshu Huang, Jingxia Li, Zhongxian Tian, Haishan Huang. The inhibitory effect of compound ChlA-F onhuman bladder cancer cell invasion can be attributed to its blockage of SOX2 protein [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 785.

Endothelial Sox17 promotes allergic airway inflammation

IL-33, levels of which are known to be increased in patients with eosinophilic asthma and which is suggested as a therapeutic target for it, activates endothelial cells in which Sry-related high-mobility-group box (Sox) 17, an endothelium-specific transcription factor, was upregulated. We investigated the relationship between Sox17 and IL-33 and the possible role of Sox17 in the pathogenesis of asthma using a mouse model of airway inflammation. We used ovalbumin (OVA) to induce airway inflammation in endothelium-specific Sox17 null mutant mice and used IL-33 neutralizing antibody to evaluate the interplay between IL-33 and Sox17. We evaluated airway inflammation and measured levels of various cytokines, chemokines, and adhesion molecules. We also carried out loss- or gain-of-function experiments for Sox17 in human endothelial cells. Levels of IL-33 and Sox17 were significantly increased in the lungs of OVA-challenged mice. Anti-IL-33 neutralizing antibody treatment attenuated not only OVA-induced airway inflammation but also Sox17 expression in pulmonary endothelial cells. Importantly, endothelium-specific deletion of Sox17 resulted in significant alleviation of various clinical features of asthma, including airway inflammation, immune cell infiltration, cytokine/chemokine production, and airway hyperresponsiveness. Sox17 deletion also resulted in decreased densities of Ly6chigh monocytes and inflammatory dendritic cells in the lungs. In IL-33-stimulated human endothelial cells, Sox17 showed positive correlation with CCL2 and intercellular adhesion molecule 1 levels. Lastly, Sox17 promoted monocyte adhesion to endothelial cells and upregulated the extracellular signal-regulated kinase-signal transducer and activator of transcription 3 pathway. Sox17 was regulated by IL-33, and its genetic ablation in endothelial cells resulted in alleviation of asthma-related pathophysiologic features. Sox17 might be a potential target for asthma management.

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.

Clinical and functional analysis of SOX9 in colorectal cancer.

519 Background: Colorectal cancer (CRC) is the third leading cause of cancer-related deaths worldwide. CRC develops within the intestinal epithelium, which is constantly self-renewing, developmental genes could promote the initiation and progression of cancer. SOX9 transcription factor is expressed especially in intestinal stem cells and in Paneth cells, thus alterations in expression could greatly promote neoplasia. However, the clinical significance and functional role of SOX9 in CRC remains unclear. The aim of this study is to investigate the association of SOX9 expression with relapse in CRC patients and initiate functional studies by evaluating the effects of silencing SOX9 in stem cells properties such as colonospheres formation in HCT116 CRC cells. Methods: 97 FFPE biopsies from CRC patients in stage I (N = 34) and stage II (N = 63) were analyzed. Immunoreactivity of SOX9 was classified as low and high expression groups based on the percentage of positive nucleus and tissue staining intensity. SOX9 silencing was achieved using a specific siRNA and Lipofectamine-RNAiMax and confirmed by qPCR 24 h postransfection. 40,000 HCT116 and HCT116-siSOX9 cells were seeded under adherent and ultra-low attachment conditions for tumorigenesis assays. After 72 h colonospheres were seeded and quantified. ROC analysis was used to assess the clinical correlation of SOX9 with relapse. Experimental data were expressed as means and differences tested by t-Student. Results: Data showed that 12.3% of patients relapsed. Interestingly, all of them showed lower SOX9 expression (p ≤ 0.05), regardless of their relapse free survival. In functional analysis, SOX9-deficient HCT116 cells formed smaller and less-compacted spheroid when compared to non-transfected HCT116 (p ≤ 0.05). Nonetheless, cell proliferation and migration under adherent condition were similar between the groups. Conclusions: This study did not find association between SOX9 expression and relapse. So far, in vitro assays results suggest that silencing of SOX9 inhibits colonospheres formation in HCT116 cells. Further investigation will be performed in order to evaluate the functional importance of SOX9 in chemotherapy response.

Correction: The role of Sox9 in collagen hydrogel-mediated chondrogenic differentiation of adult mesenchymal stem cells (MSCs).

Correction for 'The role of Sox9 in collagen hydrogel-mediated chondrogenic differentiation of adult mesenchymal stem cells (MSCs)' by Xianfang Jiang, et al., Biomater. Sci., 2018, 6, 1556-1568.

The regulation of Sox9 expression in the gonad.

The bipotential nature of cell types in the early developing gonad and the process of sex determination leading to either testis or ovary differentiation makes this an interesting system in which to study transcriptional regulation of gene expression and cell fate decisions. SOX9 is a transcription factor with multiple roles during development, including being a key player in mediating testis differentiation and therefore subsequent male development. Loss of Sox9 expression in both humans and mice results in XY female development, whereas its inappropriate activation in XX embryonic gonads can give male development. Multiple cases of Disorders of Sex Development in human patients or sex reversal in mice and other vertebrates can be explained by mutations affecting upstream regulators of Sox9 expression, such as the product of the Y chromosome gene Sry that triggers testis differentiation. Other cases are due to mutations in the Sox9 gene itself, including its own regulatory region. Indeed, rearrangements in and around the Sox9 genomic locus indicate the presence of multiple critical enhancers and the complex nature of its regulation. Here we summarize what is known about the role of Sox9 and its regulation during gonad development, including recently discovered critical enhancers. We also discuss higher order chromatin organization and how this might be involved. We end with some interesting future directions that have the potential to further enrich our understanding on the complex, multi-layered regulation controlling Sox9 expression in the gonads.

SOX2 is required for inner ear growth and cochlear nonsensory formation before sensory development.

The transcription factor sex determining region Y-box2 (SOX2) is required for the formation of hair cells and supporting cells in the inner ear and is a widely used sensory marker. Paradoxically, we demonstrate via fate mapping that, initially, SOX2 primarily marks nonsensory progenitors in the mouse cochlea, and is not specific to all sensory regions until late otic vesicle stages. SOX2 fate mapping reveals an apical-to-basal gradient of SOX2 expression in the sensory region of the cochlea, reflecting the pattern of cell cycle exit. To understand SOX2 function, we undertook a timed-deletion approach, revealing that early loss of SOX2 severely impaired morphological development of the ear, whereas later deletions resulted in sensory disruptions. During otocyst stages, SOX2 shifted dramatically from a lateral to medial domain over 24-48 h, reflecting the nonsensory-to-sensory switch observed by fate mapping. Early loss or gain of SOX2 function led to changes in otic epithelial volume and progenitor proliferation, impacting growth and morphological development of the ear. Our study demonstrates a novel role for SOX2 in early otic morphological development, and provides insights into the temporal and spatial patterns of sensory specification in the inner ear.

SOX11: friend or foe in tumor prevention and carcinogenesis?

Sex-determining region Y-related high-mobility-group box transcription factor 11 (SOX11) is an essential member of the SOX transcription factors and has been highlighted as an important regulator in embryogenesis. SOX11 studies have only recently shifted focus from its role in embryogenesis and development to its function in disease. In particular, the role of SOX11 in carcinogenesis has become of major interest in the field. SOX11 expression is elevated in a wide variety of tumors. In many cancers, dysfunctional expression of SOX11 has been correlated with increased cancer cell survival, inhibited cell differentiation, and tumor progression through the induction of metastasis and angiogenesis. Nevertheless, in a limited number of malignancies, SOX11 has also been identified to function as a tumor suppressor. Herein, we review the correlation between the expression of SOX11 and tumor behaviors. We also summarize the mechanisms underlying the regulation of SOX11 expression and activity in pathological conditions. In particular, we focus on the pathological processes of cancer targeted by SOX11 and discuss whether SOX11 is protective or detrimental during tumor progression. Moreover, SOX11 is highlighted as a clinical biomarker for the diagnosis and prognosis of various human cancer. The information reviewed here should assist in future experimental designs and emphasize the potential of SOX11 as a therapeutic target for cancer.

Fine-Tuning of Sox17 and Canonical Wnt Coordinates the Permeability Properties of the Blood-Brain Barrier.

The microvasculature of the central nervous system includes the blood-brain barrier (BBB), which regulates the permeability to nutrients and restricts the passage of toxic agents and inflammatory cells. Canonical Wnt/β-catenin signaling is responsible for the early phases of brain vascularization and BBB differentiation. However, this signal declines after birth, and other signaling pathways able to maintain barrier integrity at postnatal stage are still unknown. Sox17 (SRY [sex-determining region Y]-box 17) constitutes a major downstream target of Wnt/β-catenin in endothelial cells and regulates arterial differentiation. In the present article, we asked whether Sox17 may act downstream of Wnt/β-catenin in inducing BBB differentiation and maintenance. Using reporter mice and nuclear staining of Sox17 and β-catenin, we report that although β-catenin signaling declines after birth, Sox17 activation increases and remains high in the adult. Endothelial-specific inactivation of Sox17 leads to increase of permeability of the brain microcirculation. The severity of this effect depends on the degree of BBB maturation: it is strong in the embryo and progressively declines after birth. In search of Sox17 mechanism of action, RNA sequencing analysis of gene expression of brain endothelial cells has identified members of the Wnt/β-catenin signaling pathway as downstream targets of Sox17. Consistently, we found that Sox17 is a positive inducer of Wnt/β-catenin signaling, and it acts in concert with this pathway to induce and maintain BBB properties. In vivo, inhibition of the β-catenin destruction complex or expression of a degradation-resistant β-catenin mutant, prevent the increase in permeability and retina vascular malformations observed in the absence of Sox17. Our data highlight a novel role for Sox17 in the induction and maintenance of the BBB, and they underline the strict reciprocal tuning of this transcription factor and Wnt/β-catenin pathway. Modulation of Sox17 activity may be relevant to control BBB permeability in pathological conditions.

SOX2 as a novel contributor of oxidative metabolism in melanoma cells

BackgroundDeregulated metabolism is a hallmark of cancer and recent evidence underlines that targeting tumor energetics may improve therapy response and patient outcome. Despite the general attitude of cancer cells to exploit the glycolytic pathway even in the presence of oxygen (aerobic glycolysis or “Warburg effect”), tumor metabolism is extremely plastic, and such ability to switch from glycolysis to oxidative phosphorylation (OxPhos) allows cancer cells to survive under hostile microenvironments. Recently, OxPhos has been related with malignant progression, chemo-resistance and metastasis. OxPhos is induced under extracellular acidosis, a well-known characteristic of most solid tumors, included melanoma.MethodsTo evaluate whether SOX2 modulation is correlated with metabolic changes under standard or acidic conditions, SOX2 was silenced and overexpressed in several melanoma cell lines. To demonstrate that SOX2 directly represses HIF1A expression we used chromatin immunoprecipitation (ChIP) and luciferase assay.ResultsIn A375-M6 melanoma cells, extracellular acidosis increases SOX2 expression, that sustains the oxidative cancer metabolism exploited under acidic conditions. By studying non-acidic SSM2c and 501-Mel melanoma cells (high- and very low-SOX2 expressing cells, respectively), we confirmed the metabolic role of SOX2, attributing SOX2-driven OxPhos reprogramming to HIF1α pathway disruption.ConclusionsSOX2 contributes to the acquisition of an aggressive oxidative tumor phenotype, endowed with enhanced drug resistance and metastatic ability.

SOX4 inhibits oligodendrocyte differentiation of embryonic neural stem cells in vitro by inducing Hes5 expression

SOX4 has been shown to promote neuronal differentiation both in the adult and embryonic neural progenitors. Ectopic SOX4 expression has also been shown to inhibit oligodendrocyte differentiation in mice, however the underlying molecular mechanisms remain poorly understood. Here we demonstrate that SOX4 regulates transcriptional targets associated with neural development in neural stem cells (NSCs), reducing the expression of genes promoting oligodendrocyte differentiation. Interestingly, we observe that SOX4 levels decreased during oligodendrocyte differentiation in vitro. Moreover, we show that SOX4 knockdown induces increased oligodendrocyte differentiation, as the percentage of Olig2-positive/2′,3’-Cyclic-nucleotide 3′-phosphodiesterase (CNPase)-positive maturing oligodendrocytes increases, while the number of Olig2-positive oligodendrocyte precursors is unaffected. Conversely, conditional SOX4 overexpression utilizing a doxycycline inducible system decreases the percentage of maturing oligodendrocytes, suggesting that SOX4 inhibits maturation from precursor to mature oligodendrocyte. We identify the transcription factor Hes5 as a direct SOX4 target gene and we show that conditional overexpression of Hes5 rescues the increased oligodendrocyte differentiation mediated by SOX4 depletion in NSCs. Taken together, these observations support a novel role for SOX4 in NSC by controlling oligodendrocyte differentiation through induction of Hes5 expression.