Reversal of Postnatal Brain Astrocytes and Ependymal Cells towards a Progenitor Phenotype in Culture.

Astrocytes and ependymal cells have been reported to be able to switch from a mature cell identity towards that of a neural stem/progenitor cell. Astrocytes are widely scattered in the brain where they exert multiple functions and are routinely targeted for in vitro and in vivo reprogramming. Ependymal cells serve more specialized functions, lining the ventricles and the central canal, and are multiciliated, epithelial-like cells that, in the spinal cord, act as bi-potent progenitors in response to injury. Here, we isolate or generate ependymal cells and post-mitotic astrocytes, respectively, from the lateral ventricles of the mouse brain and we investigate their capacity to reverse towards a progenitor-like identity in culture. Inhibition of the GSK3 and TGFß pathways facilitates the switch of mature astrocytes to Sox2-expressing, mitotic cells that generate oligodendrocytes. Although this medium allows for the expansion of quiescent NSCs, isolated from live rats by "milking of the brain", it does not fully reverse astrocytes towards the bona fide NSC identity; this is a failure correlated with a concomitant lack of neurogenic activity. Ependymal cells could be induced to enter mitosis either via exposure to neuraminidase-dependent stress or by culturing them in the presence of FGF2 and EGF. Overall, our data confirm that astrocytes and ependymal cells retain a high capacity to reverse to a progenitor identity and set up a simple and highly controlled platform for the elucidation of the molecular mechanisms that regulate this reversal.

A Low Dose of Rapamycin Promotes Hair Cell Differentiation by Enriching SOX2+ Progenitors in the Neonatal Mouse Inner Ear Organoids.

PURPOSE: To investigate the impact of rapamycin on the differentiation of hair cells. METHODS: Murine cochlear organoids were derived from cochlear progenitor cells. Different concentrations of rapamycin were added into the culture medium at different proliferation and differentiation stages. RESULTS: Rapamycin exhibited a concentration-dependent reduction in the proliferation of these inner ear organoids. Nevertheless, organoids subjected to a 10-nM dose of rapamycin demonstrated a markedly increased proportion of hair cells. Furthermore, rapamycin significantly upregulated the expression of markers associated with both hair cells and supporting cells, including ATOH1, MYO7A, and SOX2. Mechanistic studies revealed that rapamycin preferentially suppressed cells without Sox2 expression during the initial proliferation stage, thereby augmenting and refining the population of SOX2+ progenitors. These enriched progenitors were predisposed to differentiate into hair cells during the later stages of organoid development. Conversely, the use of the mTOR activator MHY 1485 demonstrated opposing effects. CONCLUSION: Our findings underscore a practical strategy for enhancing the generation of inner ear organoids with a low dose of rapamycin, achieved by enriching SOX2+ progenitors in an in vitro setting.

The tale of SOX2: Focusing on lncRNA regulation in cancer progression and therapy.

Long non-coding RNAs (lncRNAs) have emerged as influential contributors to diverse cellular processes, which regulate gene function and expression via multiple mechanistic pathways. Therefore, it is essential to exploit the structures and interactions of lncRNAs to comprehend their mechanistic functions within cells. A growing body of evidence has revealed that deregulated lncRNAs are involved in multiple regulations of malignant events including cell proliferation, growth, invasion, and metabolism. SRY-related high mobility group box (SOX)2, a well-recognized member of the SOX family, is commonly overexpressed in various types of cancer, contributing to tumor progression and maintenance of stemness. Emerging studies have shown that lncRNAs interact with SOX2 to remarkably contribute to carcinogenesis and disease states. This review elaborates on the crosstalk between the intricate and complicated functions of lncRNAs and SOX2 in the context of malignant diseases. We elucidate distinct molecular mechanisms that contribute to the onset/advancement of cancer, indicating that lncRNAs/SOX2 axes hold immense promise for potential therapeutic targets. Furthermore, we delve into the modalities of emerging feasible treatment options for targeting lncRNAs, highlighting the limitations of such therapies and providing novel insights into further ameliorations of targeted strategies of lncRNAs to promote the clinical implications. Translating current discoveries into clinical applications could ultimately boost improved survival and prognosis of cancer patients.

STIM1/SOX2 proteins are co-expressed in the tumor and microenvironmental stromal cells of pancreatic ductal adenocarcinoma and ampullary carcinoma.

Pancreatic ductal adenocarcinoma (PDAC) and ampullary carcinoma (AAC) are lethal malignancies with modest benefits from surgery. SOX2 and STIM1 have been linked to anticancer activity in several human malignancies. This study included 94 tumor cases: 48 primary PDAC, 25 metastatic PDAC, and 21 primary AAC with corresponding non-tumor tissue. All cases were immunohistochemically stained for STIM1 and SOX2 and results were correlated with clinicopathologic data, patient survival, and BCL2 immunostaining results. Results revealed that STIM1 and SOX2 epithelial/stromal expressions were significantly higher in PDAC and AAC in comparison to the control groups. STIM1 and SOX2 expressions were positively correlated in the primary and metastatic PDAC (P = 0.016 and, P = 0.001, respectively). However, their expressions were not significantly associated with BCL2 expression. SOX2 epithelial/stromal expressions were positively correlated with the large tumor size in the primary AAC group (P = 0.052, P = 0.044, respectively). STIM1 stromal and SOX2 epithelial over-expressions had a bad prognostic impact on the overall survival of AAC (P = 0.002 and P = 0.001, respectively). Therefore, STIM1 and SOX2 co-expression in tumor cells and intra-tumoral stroma could contribute to the development of PDAC and AAC. STIM1/SOX2 expression is linked to a bad prognosis in AAC.

SUMO-dependent transcriptional repression by Sox2 inhibits the proliferation of neural stem cells.

Sox2 is known for its roles in maintaining the stem cell state of embryonic stem cells and neural stem cells. In particular, it has been shown to slow the proliferation of these cell types. It is also known for its effects as an activating transcription factor. Despite this, analysis of published studies shows that it represses as many genes as it activates. Here, we identify a new set of target genes that Sox2 represses in neural stem cells. These genes are associated with centrosomes, centromeres and other aspects of cell cycle control. In addition, we show that SUMOylation of Sox2 is necessary for the repression of these genes and for its repressive effects on cell proliferation. Together, these data suggest that SUMO-dependent repression of this group of target genes is responsible for the role of Sox2 in regulating the proliferation of neural stem cells.

Diagnosis of verruciform acanthotic vulvar intra-epithelial neoplasia (vaVIN) using CK17, SOX2 and GATA3 immunohistochemistry.

AIMS: Verruciform acanthotic vulvar intra-epithelial neoplasia (vaVIN) is an HPV-independent, p53 wild-type lesion with distinct morphology and documented risk of recurrence and cancer progression. vaVIN is rare, and prospective distinction from non-neoplastic hyperplastic lesions can be difficult. CK17, SOX2 and GATA3 immunohistochemistry has emerging value in the diagnosis of HPV-independent lesions, particularly differentiated VIN. We aimed to test the combined value of these markers in the diagnosis of vaVIN versus its non-neoplastic differentials in the vulva. METHODS AND RESULTS: CK17, SOX2 and GATA3 immunohistochemistry was evaluated on 16 vaVINs and 34 mimickers (verruciform xanthoma, lichen simplex chronicus, lichen sclerosus, psoriasis, pseudo-epitheliomatous hyperplasia). CK17 was scored as 3+ = full-thickness, 2+ = partial-thickness, 1+ = patchy, 0 = absent; SOX2 as 3+ = strong staining ≥ 10% cells, 2+ = moderate, 1 + =weak, 0 = staining in < 10% cells; and GATA3 as pattern 0 = loss in < 25% basal cells, 1 = loss in 25-75% basal cells, 2 = loss in > 75% basal cells. For analysis, results were recorded as positive (CK17 = 3+, SOX2 = 3+, GATA3 = patterns 1/2) or negative (CK17 = 2+/1+/0, SOX2 = 2+/1+/0, GATA3 = pattern 0). CK17, SOX2 and GATA3 positivity was documented in 81, 75 and 58% vaVINs, respectively, versus 32, 17 and 22% of non-neoplastic mimickers, respectively; ≥ 2 marker positivity conferred 83 sensitivity, 88 specificity and 86% accuracy in vaVIN diagnosis. Compared to vaVIN, SOX2 and GATA3 were differentially expressed in lichen sclerosus, lichen simplex chronicus and pseudo-epitheliomatous hyperplasia, whereas CK17 was differentially expressed in verruciform xanthoma and adjacent normal mucosa. CONCLUSIONS: CK17, SOX2 and GATA3 can be useful in the diagnosis of vaVIN and its distinction from hyperplastic non-neoplastic vulvar lesions. Although CK17 has higher sensitivity, SOX2 and GATA3 are more specific, and the combination of all markers shows optimal diagnostic accuracy.

SOX2 Expression Does Not Guarantee Cancer Stem Cell-like Characteristics in Lung Adenocarcinoma.

Effectively targeting cancer stemness is essential for successful cancer therapy. Recent studies have revealed that SOX2, a pluripotent stem cell factor, significantly contributes to cancer stem cell (CSC)-like characteristics closely associated with cancer malignancy. However, its contradictory impact on patient survival in specific cancer types, including lung adenocarcinoma (LUAD), underscores the need for more comprehensive research to clarify its functional effect on cancer stemness. In this study, we demonstrate that SOX2 is not universally required for the regulation of CSC-like properties in LUAD. We generated SOX2 knockouts in A549, H358, and HCC827 LUAD cells using the CRISPR/Cas9 system. Our results reveal unchanged CSC characteristics, including sustained proliferation, tumor sphere formation, invasion, migration, and therapy resistance, compared to normal cells. Conversely, SOX2 knockdown using conditional shRNA targeting SOX2, significantly reduced CSC traits. However, these loss-of-function effects were not rescued by SOX2 resistant to shRNA, underscoring the potential for SOX2 protein level-independent results in prior siRNA- or shRNA-based research. Ultimately, our findings demonstrate that SOX2 is not absolutely essential in LUAD cancer cells. This emphasizes the necessity of considering cancer subtype-dependent and context-dependent factors when targeting SOX2 overexpression as a potential therapeutic vulnerability in diverse cancers.

Highly cooperative chimeric super-SOX induces naive pluripotency across species.

Our understanding of pluripotency remains limited: iPSC generation has only been established for a few model species, pluripotent stem cell lines exhibit inconsistent developmental potential, and germline transmission has only been demonstrated for mice and rats. By swapping structural elements between Sox2 and Sox17, we built a chimeric super-SOX factor, Sox2-17, that enhanced iPSC generation in five tested species: mouse, human, cynomolgus monkey, cow, and pig. A swap of alanine to valine at the interface between Sox2 and Oct4 delivered a gain of function by stabilizing Sox2/Oct4 dimerization on DNA, enabling generation of high-quality OSKM iPSCs capable of supporting the development of healthy all-iPSC mice. Sox2/Oct4 dimerization emerged as the core driver of naive pluripotency with its levels diminished upon priming. Transient overexpression of the SK cocktail (Sox+Klf4) restored the dimerization and boosted the developmental potential of pluripotent stem cells across species, providing a universal method for naive reset in mammals.

E3 ubiquitin ligase RNF180 impairs IPO4/SOX2 complex stability and inhibits SOX2-mediated malignancy in ovarian cancer.

RING finger protein 180 (RNF180), an E3 ubiquitin ligase, is thought to be a tumor suppressor gene. However, the detailed mechanism of its effect on ovarian cancer (OV) has not been elucidated. Importin 4 (IPO4) which belongs to transport protein is reported to have cancer-promoting effects on OV. Here, we explored the potential signaling pathways related to RNF180 and IPO4. It was first verified that RNF180 is downregulated and IPO4 is upregulated in OV. By overexpressing or knocking down RNF180 in OV cells, we confirmed that RNF180 inhibited the malignant behaviors of OV cells both in vitro and in vivo. Bioinformatics analysis and proteomics experiments found that RNF180 could interact with IPO4 and promote the degradation of IPO4 through ubiquitination. In addition, overexpression of IPO4 removed the inhibitory effect of RNF180 on OV. We subsequently found that IPO4 could bind to the oncogene Sex determining Region Y-box 2 (SOX2). Knockdown of IPO4 in OV cells decreased SOX2 protein level in nucleus and promoted cyclin-dependent kinase inhibitory protein-1 (p21) expression. Overexpression of RNF180 also inhibited the expression of SOX2 in nucleus. All these results indicated that RNF180 inhibited the nuclear translocation of SOX2 by promoting ubiquitination of IPO4, which ultimately promoted the expression of p21 and then suppressed the progression of OV. This study verified the tumor suppressor effect of RNF180 on OV, elucidated the mechanism of the molecule network related to RNF180 and IPO4 in OV and identified for OV.

The impact of LncRNA-SOX2-OT/let-7c-3p/SKP2 Axis on head and neck squamous cell carcinoma progression: Insights from bioinformatics analysis and experimental validation.

BACKGROUND: LncRNA SRY-box transcription factor 2 overlapping transcript (SOX2-OT) is linked to multiple cancers, but its specific role and mechanism in head and neck squamous cell carcinoma (HNSCC) remain poorly understood. METHODS: We harnessed clinical data and HNSCC transcriptome profiles from UCSC Xena, TCGA, and GEO databases. Employing various algorithms, we assessed the correlation between SOX2-OT expression and the HNSCC immune microenvironment. Differential expression analysis identified immune-enriched miRNAs (DEmiRNAs) and mRNAs (DEmRNAs). Utilizing miRanda, miRWalk, and Cytoscape, we constructed a ceRNA network encompassing SOX2-OT, DEmiRNAs, and DEmRNAs. A Sankey diagram visualized pivotal SOX2-OT-miRNA-mRNA-pathways. Functional assays validated SOX2-OT silencing effects in HNSCC cells. Luciferase reporter assays verified SOX2-OT/let-7c-3p/SKP2 relationships. Additionally, a xenograft mouse model revealed SOX2-OT's impact on xenograft growth and lung metastasis. RESULTS: SOX2-OT expression demonstrated a predominantly positive correlation with B lineage and VTCN1, while manifesting a negative correlation with Neutrophil and CD47 in HNSCC tissues. We discerned a ceRNA network comprising 65 DEmiRNAs and 116 DEmRNAs, while a protein-protein interaction (PPI) network revealed 97 protein nodes among DEmRNAs. Notably, the Sankey diagram spotlighted six key DEmRNAs intricately linked to the SOX2-OT-regulated DEmiRNAs immune-related pathway. Experimental assays established that SOX2-OT silencing exerted inhibitory effects on cell proliferation, migration, tumor growth, and lung metastasis within HNSCC cells, both in vitro and in vivo. We identified let-7c-3p as a target miRNA of SOX2-OT and SKP2 as a target mRNA of let-7c-3p. CONCLUSIONS: Our study establishes the critical SOX2-OT/let-7c-3p/SKP2 axis as a pivotal regulator of HNSCC tumorigenesis and metastasis.

SOX2 promotes vasculogenic mimicry by accelerating glycolysis via the lncRNA AC005392.2-GLUT1 axis in colorectal cancer.

Vasculogenic mimicry (VM), a new model of angiogenesis, fulfills the metabolic demands of solid tumors and contributes to tumor aggressiveness. Our previous study demonstrated the effect of SOX2 in promoting VM in colorectal cancer (CRC). However, the underlying mechanisms behind this effect remain elusive. Here, we show that SOX2 overexpression enhanced glycolysis and sustained VM formation via the transcriptional activation of lncRNA AC005392.2. Suppression of either glycolysis or AC005392.2 expression curbed SOX2-driven VM formation in vivo and in vitro. Mechanistically, SOX2 combined with the promoter of AC005392.2, which decreased H3K27me3 enrichment and thus increased its transcriptional activity. Overexpression of AC005392.2 increased the stability of GLUT1 protein by enhancing its SUMOylation, leading to a decrease in the ubiquitination and degradation of GLUT1. Accumulation of GLUT1 contributed to SOX2-mediated glycolysis and VM. Additionally, clinical analyses showed that increased levels of AC005392.2, GLUT1, and EPHA2 expression were positively correlated with SOX2 and were also associated with poor prognoses in patients with CRC. Our study conclusively demonstrates that the SOX2-lncRNA AC005392.2-GLUT1 signaling axis regulates VM formation in CRC, offering a foundation for the development of new antiangiogenic drugs or new drug combination regimens.

[Prognostic model for assessing the human glioma cell malignancy grade based on MDM2, MELK, SOX2, CDK4, DR5 and OCT4 gene expression]. / Prognosticheskaya model' dlya otsenki stepeni zlokachestvennosti kul'tury kletok gliomy cheloveka na osnovanii issledovaniya ekspressii paneli genov MDM2, MELK, SOX2, CDK4, DR5 i OCT4.

Glioma cell cultures are used in basic researches of tumor processes, personalized medicine for selecting treatment regimens depending on individual characteristics of patients and pharmacology for assessing the effectiveness of chemotherapy. Suppression of glioma culture growth without reduction of malignancy grade is common. Drug cancellation may be followed by substitution of precursor cells by more malignant clones. Therefore, analysis of culture cell malignancy grade is important. In the future, intraoperative analysis of glioma cell malignancy grade can be used to select individual therapy. OBJECTIVE: We analyzed the relationship between expression of marker genes TUBB3, CD133, CDK4, CDK6, CIRBP, DR4, DR5, EGFR, FGFR, FSHR, GDNF, GFAP, L1CAM, LEF1, MAP2, MDM2, MELK, NANOG, NOTCH2, OCT4, OLIG2, PDGFRA, PDGFA, PDGFB and SOX2 and glioma cell malignancy grade, as well as created appropriate prognostic model. MATERIAL AND METHODS: We analyzed expression of 25 marker genes in 22 samples of human glioma cultures using quantitative real-time PCR. Statistical analysis was performed using the IBM SPSS Statistics 26.0 software. We used the Kolmogorov-Smirnov and Shapiro-Wilk tests to assess distribution normality. Nonparametric Jonckheere-Terpstra and Spearman tests were applied. RESULTS: We obtained a prognostic model for assessing the grade III and IV glioma cell malignancy based on expression of marker genes MDM2, MELK, SOX2, CDK4, DR5 and OCT4. Predictive accuracy was 83% (Akaike information criterion -55.125).

SOX2 promotes a cancer stem cell-like phenotype and local spreading in oral squamous cell carcinoma.

Emerging evidence shows that oral squamous cell carcinoma (OSCC) invasiveness can be attributed to a small subpopulation of cancer stem cells (CSCs) in the bulk of the tumor. However, the presence of CSCs in the OSCC close resection margins is still poorly unexplored. Here, we found that BMI1, CD44, SOX2, OCT4, UBE2C, CXCR4 CSCs marker genes are significantly upregulated, while IGF1-R, KLF4, ALDH1A1, CD133, FAM3C are downregulated in the tumor core vs healthy mucosa of 24 patients with OSCC. Among these, SOX2 appears also upregulated in the tumor close margin vs healthy mucosa and this significantly correlates with tumor size and lymph node compromise. In vitro analyses in CAL27 and SCC15 tongue squamous cell carcinoma cell lines, show that SOX2 transient knockdown i) promotes the mesenchymal-to-epithelial transition, ii) smooths the invasiveness, iii) attenuates the 3D tumor sphere-forming capacity, and iv) partially increases the sensitivity to cisplatin treatment. Overall, our study highlights that the OSCC close margins can retain CSC-specific markers. Notably, SOX2 may represent a useful CSCs marker to predict a more aggressive phenotype and a suitable target to prevent local invasiveness.

Multifaceted SOX2-chromatin interaction underpins pluripotency progression in early embryos.

Pioneer transcription factors (TFs), such as OCT4 and SOX2, play crucial roles in pluripotency regulation. However, the master TF-governed pluripotency regulatory circuitry was largely inferred from cultured cells. In this work, we investigated SOX2 binding from embryonic day 3.5 (E3.5) to E7.5 in the mouse. In E3.5 inner cell mass (ICM), SOX2 regulates the ICM-trophectoderm program but is dispensable for opening global enhancers. Instead, SOX2 occupies preaccessible enhancers in part opened by early-stage expressing TFs TFAP2C and NR5A2. SOX2 then widely redistributes when cells adopt naive and formative pluripotency by opening enhancers or poising them for rapid future activation. Hence, multifaceted pioneer TF-enhancer interaction underpins pluripotency progression in embryos, including a distinctive state in E3.5 ICM that bridges totipotency and pluripotency.

Inhibiting NR5A2 targets stemness in pancreatic cancer by disrupting SOX2/MYC signaling and restoring chemosensitivity.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is a profoundly aggressive and fatal cancer. One of the key factors defining its aggressiveness and resilience against chemotherapy is the existence of cancer stem cells (CSCs). The important task of discovering upstream regulators of stemness that are amenable for targeting in PDAC is essential for the advancement of more potent therapeutic approaches. In this study, we sought to elucidate the function of the nuclear receptor subfamily 5, group A, member 2 (NR5A2) in the context of pancreatic CSCs. METHODS: We modeled human PDAC using primary PDAC cells and CSC-enriched sphere cultures. NR5A2 was genetically silenced or inhibited with Cpd3. Assays included RNA-seq, sphere/colony formation, cell viability/toxicity, real-time PCR, western blot, immunofluorescence, ChIP, CUT&Tag, XF Analysis, lactate production, and in vivo tumorigenicity assays. PDAC models from 18 patients were treated with Cpd3-loaded nanocarriers. RESULTS: Our findings demonstrate that NR5A2 plays a dual role in PDAC. In differentiated cancer cells, NR5A2 promotes cell proliferation by inhibiting CDKN1A. On the other hand, in the CSC population, NR5A2 enhances stemness by upregulating SOX2 through direct binding to its promotor/enhancer region. Additionally, NR5A2 suppresses MYC, leading to the activation of the mitochondrial biogenesis factor PPARGC1A and a shift in metabolism towards oxidative phosphorylation, which is a crucial feature of stemness in PDAC. Importantly, our study shows that the specific NR5A2 inhibitor, Cpd3, sensitizes a significant fraction of PDAC models derived from 18 patients to standard chemotherapy. This treatment approach results in durable remissions and long-term survival. Furthermore, we demonstrate that the expression levels of NR5A2/SOX2 can predict the response to treatment. CONCLUSIONS: The findings of our study highlight the cell context-dependent effects of NR5A2 in PDAC. We have identified a novel pharmacological strategy to modulate SOX2 and MYC levels, which disrupts stemness and prevents relapse in this deadly disease. These insights provide valuable information for the development of targeted therapies for PDAC, offering new hope for improved patient outcomes. A Schematic illustration of the role of NR5A2 in cancer stem cells versus differentiated cancer cells, along with the action of the NR5A2 inhibitor Cpd3. B Overall survival of tumor-bearing mice following allocated treatment. A total of 18 PDX models were treated using a 2 x 1 x 1 approach (two animals per model per treatment); n=36 per group (illustration created with biorender.com ).

Molecular basis for SOX2-dependent regulation of super-enhancer activity.

Pioneer transcription factors (TFs) like SOX2 are vital for stemness and cancer through enhancing gene expression within transcriptional condensates formed with coactivators, RNAs and mediators on super-enhancers (SEs). Despite their importance, how these factors work together for transcriptional condensation and activation remains unclear. SOX2, a pioneer TF found in SEs of pluripotent and cancer stem cells, initiates SE-mediated transcription by binding to nucleosomes, though the mechanism isn't fully understood. To address SOX2's role in SEs, we identified mSE078 as a model SOX2-enriched SE and p300 as a coactivator through bioinformatic analysis. In vitro and cell assays showed SOX2 forms condensates with p300 and SOX2-binding motifs in mSE078. We further proved that SOX2 condensation is highly correlated with mSE078's enhancer activity in cells. Moreover, we successfully demonstrated that p300 not only elevated transcriptional activity but also triggered chromatin acetylation via its direct interaction with SOX2 within these transcriptional condensates. Finally, our validation of SOX2-enriched SEs showcased their contribution to target gene expression in both stem cells and cancer cells. In its entirety, this study imparts valuable mechanistic insights into the collaborative interplay of SOX2 and its coactivator p300, shedding light on the regulation of transcriptional condensation and activation within SOX2-enriched SEs.

Super-enhancer driven SOX2 promotes tumor formation by chromatin re-organization in nasopharyngeal carcinoma.

BACKGROUND: Nasopharyngeal carcinoma (NPC) is a malignant head and neck cancer with a high incidence in Southern China and Southeast Asia. Patients with remote metastasis and recurrent NPC have poor prognosis. Thus, a better understanding of NPC pathogenesis may identify novel therapies to address the unmet clinical needs. METHODS: H3K27ac ChIP-seq and HiChIP was applied to understand the enhancer landscapes and the chromosome interactions. Whole genome sequencing was conducted to analyze the relationship between genomic variations and epigenetic dysregulation. CRISPRi and JQ1 treatment were used to evaluate the transcriptional regulation of SOX2 SEs. Colony formation assay, survival analysis and in vivo subcutaneous patient-derived xenograft assays were applied to explore the function and clinical relevance of SOX2 in NPC. FINDINGS: We globally mapped the enhancer landscapes and generated NPC enhancer connectomes, linking NPC specific enhancers and SEs. We found five overlapped genes, including SOX2, among super-enhancer regulated genes, survival related genes and NPC essential genes. The mRNA expression of SOX2 was repressed when applying CRISPRi targeting different SOX2 SEs or JQ1 treatment. Next, we identified a genetic variation (Chr3:181422197, G > A) in SOX2 SE which is correlated with higher expression of SOX2 and poor survival. In addition, SOX2 was highly expressed in NPC and is correlated with short survival in patients with NPC. Knock-down of SOX2 suppressed tumor growth in vitro and in vivo. INTERPRETATION: Our study demonstrated the super-enhancer landscape with chromosome interactions and identified super-enhancer driven SOX2 promotes tumorigenesis, suggesting that SOX2 is a potential therapeutic target for patients with NPC. FUNDING: A full list of funding bodies that contributed to this study can be found in the Acknowledgements section.

LncRNA WAC-AS1 promotes osteosarcoma Metastasis and stemness by sponging miR-5047 to upregulate SOX2.

Cancer stemness and osteosarcoma (OS) malignant progression are closely associated. However, the molecular mechanisms underlying this association have not been fully demonstrated. Long noncoding RNAs (lncRNAs) are an intriguing class of widely prevalent endogenous RNAs involved in OS progression, the vast majority of which have not been characterized functionally. Here, we identified tumor promoter lncRNA WAC-AS1 to be highly expressed in OS tumors and associated with worse survival. Further analysis revealed that WAC-AS1 increased tumorsphere formation of OS cells and promoted metastasis, as confirmed by cell proliferation, transwell and wound healing assays. MiR-5047 was identified as a downstream target of WAC-AS1. Subsequently, based on bioinformatics analysis, RIP assay and luciferase reporter assay, SOX2 mRNA was verified as a target of miR-5047. WAC-AS1 enhanced OS cell proliferation and stemness via acting as a ceRNA by binding to miR-5047, thereby increasing SOX2 expression. In addition, SOX2 bound to the promoter region of WAC-AS1 and promoted its transcription, thereby forming a positive feedback loop to regulate OS malignancy. Taken together, our findings show WAC-AS1 is a tumor promoter and a key regulator of OS cell stemness and metastasis via a miR-5047/SOX2 axis.

Fluctuation of CD9/SOX2-positive cell populations during the turnover of GH- and TSH-producing cells in the adult anterior pituitary gland.

The adenohypophysis is comprised of the anterior and intermediate lobes (AL and IL, respectively). Cluster of differentiation 9 (CD9)- and sex-determining region Y-box 2 (SOX2)-positive cells are stem/progenitor hormone-producing cells in the AL. They are located in the marginal cell layer (MCL) facing Rathke's cleft between the AL and IL (primary niche) and the parenchyma of the AL (secondary niche). We previously showed that, in rats, CD9/SOX2-positive cells in the IL side of the MCL (IL-side MCL) migrate to the AL side (AL-side MCL) and differentiate into prolactin-producing cells (PRL cells) in the AL parenchyma during pregnancy, lactation, and diethylstilbestrol treatment, all of which increase PRL cell turnover. This study examined the changes in CD9/SOX2-positive stem/progenitor cell niches and their proportions by manipulating the turnover of growth hormone (GH)- and thyroid-stimulating hormone (TSH)-producing cells (GH and TSH cells, respectively), which are Pit1 lineage cells, as well as PRL cells. After induction, the isolated CD9/SOX2-positive cells from the IL-side MCL formed spheres and differentiated into GH and TSH cells. We also observed an increased GH cell proportion upon treatment with GH-releasing hormone and recovery from continuous stress and an increased TSH cell proportion upon propylthiouracil treatment, concomitant with alterations in the proportion of CD9/SOX2-positive cells in the primary and secondary niches. These findings suggest that CD9/SOX2-positive cells have the potential to supply GH and TSH when an increase in GH and TSH cell populations is required in the adult pituitary gland.

Hepatitis B Virus x Protein Increases Cellular OCT3/4 and MYC and Facilitates Cellular Reprogramming.

Hepatitis B virus x (HBx) is a multifunctional protein coded by the Hepatitis B virus that is involved in various cellular processes such as proliferation, cell survival/apoptosis, and histone methylation. HBx was reported to be associated with liver "cancer stem cells." The stemness inducing properties of HBx could also facilitate the generation of pluripotent stem cells from somatic cells. It is well established that somatic cells can be reprogrammed to induced pluripotent stem cells (iPSCs) using a cocktail of transcription factors called Yamanaka's factors (YFs) (OCT4, SOX2, KLF4, and MYC). The reprogramming process proceeds step-by-step with reprogramming factor chromatin interactions, transcription, and chromatin states changing during transitions. HBx is a "broad spectrum trans-activator" and therefore could facilitate these transitions. We electroporated low passage and high passage (difficult to reprogram) fibroblasts using YFs with and without HBx and evaluated the reprogramming efficiency. We also investigated the tri-lineage and terminal differentiation potential of iPSC derived using HBx. We found that the addition of HBx to YF improves iPSC derivation, and it increases the efficiency of iPSC generation from "difficult or hard-to-reprogram samples" such as high passage/senescent fibroblasts. Further, we show that HBx can substitute the key transcription factor MYC in the YF cocktail to generate iPSC. The cellular levels of OCT3/4 and MYC were increased in HBx expressing cells. Our results have practical value in improving the efficiency of pluripotent stem cell derivation from "difficult to reprogram" somatic cells, in addition to providing some insights into the mechanisms of liver carcinogenesis in chronic hepatitis B. To conclude, HBx improves the reprogramming efficiency of YFs. HBx increases the cellular levels of OCT3/4 and MYC.