Sex-determining Region Y-box 2 Overexpression Research Articles

Activin and Hepatocyte Growth Factor Promotes Colorectal Cancer Stemness and Metastasis through FOXM1/SOX2/CXCR4 Signaling.

Cancer stem cells (CSCs) are believed to drive tumor development and metastasis. Activin and hepatocyte growth factor (HGF) are important cytokines with the ability to induce cancer stemness. However, the effect of activin and HGF combination treatment on CSCs is still unclear. In this study, we sequentially treated colorectal cancer cells with activin and HGF and examined CSC marker expression, self-renewal, tumorigenesis, and metastasis. The roles of forkhead box M1 (FOXM1) and sex-determining region Y-box 2 (SOX2), two stemness-related transcription factors, in activin/HGF-induced aggressive phenotype were explored. Activin and HGF treatment increased the expression of CSC markers and enhanced sphere formation in colorectal cancer cells. The tumorigenic and metastatic capacities of colorectal cancer cells were enhanced upon activin and HGF treatment. Activin and HGF treatment preferentially promoted stemness and metastasis of CD133+ subpopulations sorted from colorectal cancer cells. FOXM1 was upregulated by activin and HGF treatment, and the knockdown of FOXM1 blocked activin/HGF-induced stemness, tumorigenesis, and metastasis of colorectal cancer cells. Similarly, SOX2 was silencing impaired sphere formation of activin/HGF-treated colorectal cancers. Overexpression of SOX2 rescued the stem cell-like phenotype in FOXM1-depleted colorectal cancer cells with activin and HGF treatment. Additionally, the inhibition of FOXM1 via thiostrepton suppressed activin/HGF-induced stemness, tumorigenesis and metastasis. Sequential treatment with activin and HGF promotes colorectal cancer stemness and metastasis through activation of the FOXM1/SOX2 signaling. FOXM1 could be a potential target for the treatment of colorectal cancer metastasis.

Glucocorticoids inhibit the maturation of committed osteoblasts via SOX2.

During bone formation, mesenchymal progenitor cells mature into bone-forming osteoblasts after undergoing several stages of differentiation. Impaired bone formation is a predominant finding in glucocorticoid (GC)-induced osteoporosis (GIO). Osteoblasts at different stages of maturation can be affected by excessive endogenous or therapeutic GCs. Sex-determining region Y-box 2 (SOX2) is normally expressed in immature osteoblasts, but its overexpression can suppress osteoblast differentiation. This study aimed to evaluate whether GC affects SOX2 expression in osteoblasts, and whether SOX2 contributes to GC-induced inhibition of osteoblast differentiation. Treatment with GCs such as dexamethasone (Dex) or hydrocortisone enhanced SOX2 expression. Silencing SOX2 improved inhibition of GC-induced osteoblast differentiation, whereas SOX2 overexpression decreased mineralized nodule formation and RUNX2 and Osterix expression in MC3T3-E1 cells. On the contrary, when C3H10T1/2 uncommitted mesenchymal stem cells were subjected to SOX2 overexpression, RUNX2 expression increased. As a mechanism of Dex-induced SOX2 upregulation in preosteoblasts, we found that the STAT3 pathway or GC receptor (GR) is involved, using a GR antagonist, STAT3 regulators, and chromatin immunoprecipitation assays. Moreover, mice treated with Dex for 4 weeks showed a notable increase in SOX2 expression in the bones and an increased ratio of procollagen type 1 N-terminal propeptide to osteocalcin in the plasma than in control mice. This study demonstrated that GC enhances SOX2 expression in vitro in osteoblast and in vivo in the mice bone, which affects bone-forming activity differently depending on the differentiation stage of osteoblast-lineage cells. Our results provide new insights into prevention and treatment against impaired bone formation in GIO.

SOX2 modulated astrocytic process plasticity is involved in arsenic-induced metabolic disorders

Metabolic disorders induced by arsenic exposure have attracted great public concern. However, it remains unclear whether hypothalamus-based central regulation mechanisms are involved in this process. Here, we exposed mice to 100 μg/L arsenic in drinking water and established a chronic arsenic exposure model. Our study revealed that chronic arsenic exposure caused metabolic disorders in mice including impaired glucose metabolism and decreased energy expenditure. Arsenic exposure also impaired glucose sensing and the activation of proopiomelanocortin (POMC) neurons in the hypothalamus. In particular, arsenic exposure damaged the plasticity of hypothalamic astrocytic process. Further research revealed that arsenic exposure inhibited the expression of sex-determining region Y-Box 2 (SOX2), which decreased the expression level of insulin receptors (INSRs) and the phosphorylation of AKT. The conditional deletion of astrocytic SOX2 exacerbated arsenic-induced effects on metabolic disorders, the impairment of hypothalamic astrocytic processes, and the inhibition of INSR/AKT signaling. Furthermore, the arsenic-induced impairment of astrocytic processes and inhibitory effects on INSR/AKT signaling were reversed by SOX2 overexpression in primary hypothalamic astrocytes. Together, we demonstrated here that chronic arsenic exposure caused metabolic disorders by impairing SOX2-modulated hypothalamic astrocytic process plasticity in mice. Our study provides evidence of novel central regulatory mechanisms underlying arsenic-induced metabolic disorders and emphasizes the crucial role of SOX2 in regulating the process plasticity of adult astrocytes.

SOX2 and Bcl-2 as a Novel Prognostic Value in Hepatocellular Carcinoma Progression.

Sex-determining region Y-box 2 (SOX2) is a stem cell transcription factor and a major regulator of self-renewal and pluripotency of cancer stem cells (CSCs). In many types of cancer, SOX2 is dysregulated due to overexpression associated with tumor progression and low survival rate. Many HCC cases encounter recurrence and metastasis which might be due to CSCs and also apoptosis. Since little is known about the expression pattern of SOX2 and apoptotic genes in HCC, we aimed to determine the prognostic significance of SOX2, Bax, and Bcl-2 in clinicopathological features, tumor progression, and survival rate of the HCC patients. The expression of SOX2, Bax, and Bcl-2 were evaluated using qRT-PCR in 53 formalin-fixed, paraffin-embedded tissues (FFPE) of patients and 44 controls. Correlation of these genes was analyzed with clinicopathological features and tumor progression. The correlationship between SOX2 expression and ALBI grade as prognostic indicators were calculated. Survival rates were determined by Kaplan–Meier survival curves. SOX2 and Bcl-2 were remarkably overexpressed in HCC patients compared to controls (p = 0.04 and p = 0.003, respectively). A significant association was found for both SOX2 and Bcl-2 overexpression with TNM staging (p = 0.02, p = 0.04) and tumor grading (p = 0.01, p = 0.003), respectively. A significant correlation was observed: patients with SOX2 overexpression had a lower 5-year overall survival rate (p = 0.04); however, there was no significant association between Bcl-2 and survival (p = 0.5). Collectively, overexpression of SOX2 and Bcl-2, alone or combined, may be a potential marker to evaluate prognosis and response to HCC treatment.

Regulation of cancer stem cell properties, angiogenesis, and vasculogenic mimicry by miR-450a-5p/SOX2 axis in colorectal cancer

Growing evidence indicates that a small number of cancer cells express stem cell markers and possess stem cell-like properties that promote malignant progression. Sex-determining region Y-box2 (SOX2) is a stem cell transcription factor essential for maintaining the properties of cancer stem cell (CSC). As CSC properties have been associated with angiogenesis and vasculogenic mimicry (VM), we aimed to comprehensively investigate whether SOX2 regulates CSC properties, angiogenesis, and VM in colorectal carcinoma (CRC) and its potential mechanism in this study. For this study, sphere formation assay, flow cytometry, cell survival analysis, tube formation, 3D culture, immunoblot, mouse model, and luciferase reporter assay were performed in vivo and in vitro. Expressions of SOX2 and miR-450a-5p in CRC tissue samples were examined through immunohistochemistry. First, the expression of SOX2 was not only associated with poor differentiation and prognosis but also promoted angiogenesis and VM. Knockdown of SOX2 ceased stemness properties, angiogenesis, and VM, along with decreased expression of CD133, CD31, and VE-cadherin as observed in functional experiments. Downregulation of SOX2 was found to inhibit tumorigenesis in vivo. Second, miR-450a-5p suppressed the expression of SOX2 by targeting its 3’UTR region directly and hence restrained SOX2-induced CSC properties, angiogenesis, and VM. Moreover, SOX2 overexpression preserved the miR-450a-5p-induced inhibition of CRC properties, angiogenesis, and VM. Finally, clinical samples exhibited a negative correlation between miR-450a-5p and SOX2. Patients with higher SOX2 and lower miR-450a-5p expressions had a poorer prognosis than patients with inverse expressions. Conclusively, we elucidated a unique mechanism of miR-450a-5p-SOX2 axis in the regulation of stemness, angiogenesis, and VM, which may act as a potential therapeutic practice in CRC.

Extra Virgin Olive Oil Contains a Phenolic Inhibitor of the Histone Demethylase LSD1/KDM1A.

The lysine-specific histone demethylase 1A (LSD1) also known as lysine (K)-specific demethylase 1A (KDM1A) is a central epigenetic regulator of metabolic reprogramming in obesity-associated diseases, neurological disorders, and cancer. Here, we evaluated the ability of oleacein, a biophenol secoiridoid naturally present in extra virgin olive oil (EVOO), to target LSD1. Molecular docking and dynamic simulation approaches revealed that oleacein could target the binding site of the LSD1 cofactor flavin adenosine dinucleotide with high affinity and at low concentrations. At higher concentrations, oleacein was predicted to target the interaction of LSD1 with histone H3 and the LSD1 co-repressor (RCOR1/CoREST), likely disturbing the anchorage of LSD1 to chromatin. AlphaScreen-based in vitro assays confirmed the ability of oleacein to act as a direct inhibitor of recombinant LSD1, with an IC50 as low as 2.5 μmol/L. Further, oleacein fully suppressed the expression of the transcription factor SOX2 (SEX determining Region Y-box 2) in cancer stem-like and induced pluripotent stem (iPS) cells, which specifically occurs under the control of an LSD1-targeted distal enhancer. Conversely, oleacein failed to modify ectopic SOX2 overexpression driven by a constitutive promoter. Overall, our findings provide the first evidence that EVOO contains a naturally occurring phenolic inhibitor of LSD1, and support the use of oleacein as a template to design new secoiridoid-based LSD1 inhibitors.

Abstract 3125: SOX2 controls the tumor initiation and development and acts as a prognostic predictor of oral squamous cell carcinoma

Abstract Background: Sex determining region Y-BOX2 (SOX2), a regulator of the self-renewal ability of stem cells, plays a compelling role in initiation and development of cancer. However, little is known about the role and network controlling of SOX2 in oral squamous cell carcinoma (OSCC) development. Method: In this study, we conducted a retrospective cohort of 229 OSCC patients from two independent Chinese centers from May 2003 to August 2012. SOX2 expression in these samples was determined by immunostaining. Univariate and multivariate analyses were performed. Then we generated SOX2-creERT2 mice that expressing an inducible Cre recombinase under the control of a minimal promoter of SOX2, along with a tdTomato reporter. These mice were exposed to low dose 4NQO in the drinking water either for 8, 12 or 16 weeks. We further investigate the network controlling of SOX2 by ChIP assay. Then we detected the expression of SOX2 in response to AFF4 knockdown and overexpression by western blot, respectively. Furthermore, we used wound-healing, transwell, sphere formation and limiting dilution assay to confirm whether SOX2 expression was regulated by AFF4. Results: In the multiple cohorts, high SOX2 protein expression was negatively correlated with the overall survival for OSCC patients. Impressively, we found chemotherapy only improved outcomes of patients with low SOX2 expression, but very limited effects to high SOX2 expression patients. Meanwhile low SOX2 expression patients had significantly better survival with rather than without chemotherapies. Lineage tracing study in vivo suggested that SOX2 positive cells play an important role in the carcinogenesis of OSCC as epithelial stem cells. Increasing SOX2 positive cells and their daughter cells was a major trigger in the initiation of OSCC. Mechanistically, we found SOX2 was regulated by AFF4, the core component of Super elongation complex (SEC) to promote the proliferation, migration and invasion of OSCC cells. SOX2 expression changed in parallel with AFF4 expression in response to depletion and overexpression of AFF4, respectively. More importantly, the inhibited proliferation, migration, invasion and ALDH activity induced by knockdown of AFF4 in OSCC cells were rescued by overexpression of SOX2. Conclusion: Collectively, our findings indicate SOX2 acts as a prognostic predictor and controls the tumor initiation and development in oral squamous cell carcinoma. SOX2 may serve as a potential target of therapies for patients with OSCC. Note: This abstract was not presented at the meeting. Citation Format: ZIHAO WEI, FENGYING YIN, PENG DENG, XUEFENG ZHANG, JING DENG, JING LI, LIANG XIE, QIANMING CHEN. SOX2 controls the tumor initiation and development and acts as a prognostic predictor of oral squamous cell carcinoma [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 3125.

SOX2 Activation Using CRISPR/dCas9 Promotes Wound Healing in Corneal Endothelial Cells.

There are no effective treatments for corneal endothelial diseases, except for corneal transplantation, as human corneal endothelial cells (hCECs) do not regenerate. The regeneration of hCECs could be induced through regulation of the expression of specific genes. In this study, we investigated whether the overexpression of sex-determining region Y-box 2 (SOX2) can regenerate hCECs in vivo and in vitro. SOX2 was activated using the clustered regularly interspaced short palindromic repeats (CRISPR)/deactivated CRISPR-associated protein 9 (dCas9) activation system. Genes were transfected into the corneal endothelium of Sprague-Dawley rats. Central corneal thickness and opacity were measured, and alizarin red S staining was performed. Corneal opacity and central corneal thickness were reduced in the SOX2 group compared with the control group. The density of CECs was higher in the SOX2 group compared with the control group. Additionally, hCECs were cultured and analyzed after overexpressing SOX2. Cell viability, proliferation rate, and the number of cells in S-phase were increased after SOX2 overexpression (p < .05). Cyclin-dependent kinase 1 and cyclin D1 were found to be overexpressed (p < .05). WNT signaling was repressed, and the AKT pathway was activated by SOX2 overexpression. Mitochondrial oxidative stress and energy production were increased by SOX2 overexpression (p < .05). In conclusion, SOX2 activation promotes wound healing and regeneration in CECs. SOX2 activation using the CRISPR/dCas9 system may thus be useful for the treatment of hCEC diseases. Stem Cells 2018;36:1851-12.

Abstract B73: SOX2 regulation of FOXP1 as a mechanism driving disparate aggressiveness of prostate cancer in African-American men

Abstract Background: Although organ-confined, moderately graded prostate cancer has encouraging cure rates, progression to castration-resistant prostate cancer (CRPC) from advanced, high-grade lesions represents the lethal form of this malignancy, for which current therapeutic modalities are only palliative; patients with CRPC will die from their disease. Importantly, African-American (AA) men exhibit both a higher incidence of prostate cancer diagnoses and are at higher risk of developing CRPC as compared to other racial groups. Currently, the mechanisms driving prostate cancer disparities in AA men are poorly understood, and new biomarkers and novel drugs to address this disparity are in high demand to improve personalized medicine and clinical management of prostate cancer in AA men. Work by our group and others has identified SOX2 (sex determining region Y-box 2), an essential transcription factor for maintaining the survival and pluripotency of undifferentiated embryonic stem cells (ESCs), to be associated with aggressive prostate cancer and that the constitutive overexpression of SOX2 in a hormone-sensitive, SOX2-negative prostate cancer cell line is sufficient to generate a castration-resistant phenotype both in vitro and in vivo. Further, our data demonstrate canonical SOX2 transcriptional cofactors OCT4 and NANOG are frequently not expressed in prostate cancer, implying that SOX2 has unique, non-stem cell gene targets and binding partners within malignant prostate malignancies. Methods and Results: To elucidate such SOX2 gene targets in CRPC, we performed SOX2 chromatin immunoprecipitation and sequencing (ChIP-Seq) in prostate cancer cells, revealing SOX2 binding of several interesting and functionally important gene target promoters, including FOXP1, an AR target gene and transcription factor known to play a role in disparate aggressiveness of prostate cancer in African-American men. Based on these findings, we hypothesize that upon AR ablation in prostate cancer treatment, FOXP1, a tumor suppressor demonstrated to be associated with disparate prostate cancer aggressiveness in AA men, is repressed by SOX2 to drive CRPC in AA men. Work to test this hypothesis is currently under way, and includes (1) assessment of differential FOXP1 gene expression using MDA-PCa-2a, MDA-PCa-2b, and EA0066-hT, prostate cancer cell lines derived from AA men, and CWRR1, CWR22Rv1, and LNCaP, prostate cancer cell lines derived from CA men overexpressing SOX2 in the context of AR ablation; and (2) FOXP1 ChIP-Seq paired with RNA-Seq in tumor tissues prospectively collected from AA and CA men with prostate cancer undergoing radical prostatectomy. Conclusion: The work proposed herein represents an in-depth exploration of basic SOX2 biology in the context of CRPC, is highly innovative and translational, and has transformative potential to improve clinical patient management and eradicate disparities in CRPC. Note: This abstract was not presented at the conference. Citation Format: Anthony Williams, Larischa de Wet, Marc Gillard, Steve Kregel, Tzintzuni Garcia, Russell Szmulewitz, Don Vander Griend. SOX2 regulation of FOXP1 as a mechanism driving disparate aggressiveness of prostate cancer in African-American men [abstract]. In: Proceedings of the Tenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2017 Sep 25-28; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2018;27(7 Suppl):Abstract nr B73.

AFF4 promotes tumorigenesis and tumor-initiation capacity of head and neck squamous cell carcinoma cells by regulating SOX2.

Super elongation complex (SEC) controls gene transcription by releasing Pol II from pausing. Previous studies have shown that dysfunction of SEC was associated with multiple human cancers, such as leukemia and breast cancer. However, the role of SEC in head and neck squamous cell carcinoma (HNSCC) development remains largely unknown. In this study, we found expression of AF4/FMR2 family member 4 (AFF4), the core component of SEC, was upregulated dramatically in HNSCC cell lines and tumor tissues. By using siRNA-mediated depletion and overexpression of AFF4, we demonstrated AFF4 promoted proliferation, migration and invasion of HNSCC cells. Moreover, we found AFF4 enhanced the aldehyde dehydrogenase (ALDH) activity and sphere formatting activity and was required for the tumor-initiation capacity of stem-like cells in HNSCC cell lines. Mechanistically, we found the role of AFF4 in regulation of HNSCC cell behaviors was mainly mediated by sex-determining region Y box2 (SOX2), a critical regulator involved in development of several human cancers. SOX2 expression changed in parallel with AFF4 expression in response to depletion and overexpression of AFF4, respectively. More importantly, overexpression of SOX2 rescued the inhibited proliferation, migration, invasion and ALDH activity induced by knockdown of AFF4 in HNSCC cells, at least in part. Collectively, our findings indicate AFF4 may serve as a biomarker and a potential target of therapies for patients with HNSCC.

Expression of sex determining region Y-box 2 in hepatocellular carcinoma tissues and effect on the SMMC-7721 proliferation, invasion and migration

Objective To investigate the association between the clinical significance and the expression of sex determining region Y-box 2 (SOX2) in hepatocellular carcinoma (HCC), and to elucidate the its effect on proliferation, migration and invasion of SMMC-7721 cells. Methods We evaluated the clinical significance of SOX2 in 32 HCC patients using immunohistochemistry. The effects of SOX2 on the proliferation, invasion and migration of HCC cells were detected by clone formation and Transwell assay in vitro. Results The expression of SOX2 was up-regulated in the human HCC tissues. The positive rate of SOX2 in cancer tissue, para cancer tissue and normal liver tissue was 73.8%, 32.5% and 12.4%, respectively (P=0.008, 0.006). Clone formation experiment results showed that clone formation number of SOX2 overexpression cells (654.9±39.4) was significantly greater than that of control group (232.7±19.4, P=0.000). In vitro, the characteristics of epithelial-mesenchymal transition (EMT) were induced by lentivirus transduction of SOX2 into SMMC-7721 cells, including the down-regulation of E-cadherin, and ZO-1, and the concomitant up-regulation of N-cadherin and Fibronectin. The overexpression of SOX2 in the HCC cell line promoted cell motility and invasion. Conclusion Our findings have uncovered a novel role for SOX2 in HCC metastasis, and provide a potential therapeutic target for HCC therapy. Key words: Carcinoma, hepatocellular; Sex determining region Y-box 2; Epithelial-mesenchymal transition; Proliferation; Invasion; Migration

PHF20 collaborates with PARP1 to promote stemness and aggressiveness of neuroblastoma cells through activation of SOX2 and OCT4.

The differentiation status of neuroblastoma (NB) strongly correlates with its clinical outcomes; however, the molecular mechanisms driving maintenance of stemness and differentiation remain poorly understood. Here, we show that plant homeodomain finger-containing protein 20 (PHF20) functions as a critical epigenetic regulator in sustaining stem cell-like phenotype of NB by using CRISPR/Cas9-based targeted knockout (KO) for high-throughput screening of gene function in NB cell differentiation. The expression of PHF20 in NB was significantly associated with high aggressiveness of the tumor and poor outcomes for NB patients. Deletion of PHF20 inhibited NB cell proliferation, invasive migration, and stem cell-like traits. Mechanistically, PHF20 interacts with poly(ADP-ribose) polymerase 1 (PARP1) and directly binds to promoter regions of octamer-binding transcription factor 4 (OCT4) and sex determining region Y-box 2 (SOX2) to modulate a histone mark associated with active transcription, trimethylation of lysine 4 on histone H3 protein subunit (H3K4me3). Overexpression of OCT4 and SOX2 restored growth and progression of PHF20 KO tumor cells. Consistently, OCT4 and SOX2 protein levels in clinical NB specimens were positively correlated with PHF20 expression. Our results establish PHF20 as a key driver of NB stem cell-like properties and aggressive behaviors, with implications for prognosis and therapy.

Abstract 2440: Cross-tissue interactome analyses unravel novel oncogenic roles of SOX2

Abstract First recognized for its significance in early embryogenesis, SOX2 (sex determining region Y box 2) more recently received major attention as a (i) transcriptional master regulator of stemness driving the re-programming of terminally differentiated somatic cells back into a pluripotent stem cell state and (ii) powerful oncogene of the cancer stem cell (CSC) compartment. We and others have shown that SOX2 expression relies on canonical PI3K/AKT signaling involving direct physical contact and phospho-modification by AKT. Interestingly, we observed that these interactions are highly tissue specific which prompted us to perform a systematic proteomic analysis of co-factors regulating SOX2 biology. The SOX2 interactome was analyzed in human breast carcinoma and glioblastoma cell lines by co-immunoprecipitation (co-IP) and HPLC/MS revealing &amp;gt;900 individual and &amp;gt;70 conserved proteinaceous co-factors, thus underscoring a hitherto underestimated scaffolding function of SOX2. As expected, a major proportion of binding partners cluster in functional categories implicated in DNA binding and/or nucleotide modification (e.g. helicases, transferases, and ligases). However, a near equal share of SOX2 associated factors fall into functional classes formally unrelated to transcription modulation such as cell adhesion, cytoskeletal organization, or metabolic adaptation. Using SOX2 knock-down and overexpression cells generated by lentiviral technology, we confirm co-regulation of SOX2 with selected binding partners. Moreover, we observe co-depletion of SOX2 and protein co-factors in cells of stalled AKT activity, and a molecular restoration of both upon proteasomal inhibition. We conclude that, besides its known significance in DNA activity control, the SOX2 protein engages in various interactions seemingly unrelated to transcription modulation. These newly discovered interactions are likely to synergize with canonical SOX2 functions (i.e. the induction and maintenance of stemness), but involve regulation at post-translational level and of extra-nuclear components. Our efforts thus add an exciting new facet to SOX2 biology and eventually, may open new therapeutic avenues for targeted anti-CSC therapy. Citation Format: Thorsten Schaefer, Silvia Candido, Hui Wang, Thomas Bock, Alexander Schmidt, Claudia Lengerke. Cross-tissue interactome analyses unravel novel oncogenic roles of SOX2 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2440. doi:10.1158/1538-7445.AM2017-2440

Sox2-dependent inhibition of p21 is associated with poor prognosis of endometrial cancer.

Sex‐determining region Y‐box 2 (SOX2) is an essential factor involved in the self‐renewal and pluripotency of embryonic stem cells and has functions in cell survival and progression in many types of cancers. Here, we found that several endometrial cancer cell lines expressed SOX2, which was required for cell growth. Additionally, SOX2 overexpression regulated the expression of cyclin‐dependent kinase inhibitor 1A (CDKN1A), and SOX2 specifically bound to p21 promoter DNA in endometrial cancer cell lines expressing SOX2. Expressions of SOX2 in endometrial cancer patients were significantly correlated with histological grade and poor prognosis. Moreover, low p21 together with high SOX2 expressions in advanced endometrial cancer patients were associated with the most unfavorable outcomes of patients. These results indicated that simultaneous measurement of SOX2 and p21 expression in endometrial cancer patients may be a useful biomarker for patient prognosis.

Sex-Determining Region Y-box 2 Promotes Growth of Lung Squamous Cell Carcinoma and Directly Targets Cyclin D1

Sex-determining region Y-box 2 (SOX2) is an oncogene known to be amplified and overexpressed in various human malignancies, including lung squamous cell carcinoma (SCC). However, the role played by SOX2 in lung SCC development remains to be elucidated. We measured the levels of SOX2 and cyclin D1 mRNA and protein expression in lung SCC tissues and a lung SCC cell line, and found that both levels were dramatically upregulated in specimens of lung SCC tissue when compared with their expression levels in samples of adjacent nonneoplastic tissue. The lung SCC cell line also showed higher levels of SOX2 and cyclin D1 expression than a normal human bronchial epithelium cell line. After using RNA interference to knock down SOX2 expression in NCI-H520 lung SCC cells, their proliferation was reduced. Furthermore, overexpression of SOX2 promoted the proliferation of normal human bronchial epithelium cells. To further determine whether cyclin D1 was downstream target gene of SOX2, we measured the levels of cyclin D1 expression that occurred when SOX2 was knocked down or overexpressed. SOX2 knockdown significantly decreased the levels of cyclin D1 mRNA and protein expression, while SOX2 overexpression upregulated the levels of cyclin D1. We used bioinformatics data to identify potential cyclin D1 promoter binding sites for SOX2. Results of luciferase reporter assays, electrophoretic mobility shift assays, and chromatin immunoprecipitation assays confirmed that cyclin D1 was a direct target of transcription factor SOX2 in human lung SCC cells.

MicroRNA-101 Inhibits Growth, Proliferation and Migration and Induces Apoptosis of Breast Cancer Cells by Targeting Sex-Determining Region Y-Box 2

Background: Increasing evidence has demonstrated that microRNAs play a critical role in breast cancer (BC) progression. microRNA-101 (miR-101) has been considered a tumor suppressive miRNA in different cancer types. This study aimed to investigate miR-101 expression in BC tissues and to investigate its roles in BC progression that are mediated by Sex-determining region Y-box 2 (SOX2), a critical oncogene in various cancers. Methods: qRT-PCR and immunohistochemistry were performed to detect miR-101 and SOX2 expression in BC tissues and paired normal tissues or BC cell lines. MTT, transwell migration, wound healing, colony formation, flow cytometric and xenograft assays were performed to determine the influence of miR-101 and SOX2 on the malignant behaviors of BC cells in vitro and in vivo. Results: miR-101 was significantly downregulated in BC tissues and cell lines. miR-101 overexpression inhibited the malignant behaviors of BC cells, both in vitro and in vivo. miR-101 downregulation had the converse effect. A miR-101 binding site was identified by luciferase reporter assay in the 3’UTR of SOX2. SOX2 was upregulated in BC tissues and cell lines, and its upregulation was associated with lymph node metastasis, pathological grade and TNM classification. SOX2 knockdown mimicked the effects of miR-101 overexpression on the malignant behaviors of BC cells, while SOX2 overexpression mitigated the miR-101-induced inhibition of these effects. Conclusions: Our study revealed that miR-101 plays a critical role in suppressing tumor progression by directly targeting SOX2.

Overexpression of SOX2 is involved in paclitaxel resistance of ovarian cancer via the PI3K/Akt pathway.

Paclitaxel is recommended as a first-line chemotherapeutic agent against ovarian cancer, but drug resistance becomes a major limitation of its success clinically. The key molecule or mechanism associated with paclitaxel resistance in ovarian cancer still remains unclear. Sex-determining region Y-box 2 (SOX2) is of vital importance in the regulation of stem cell proliferation and carcinogenesis. The aim of this study was to evaluate the role of SOX2 in ovarian cancer tumorigenesis and paclitaxel resistance. In the present study, the expression of SOX2 was examined by immunohistochemistry (IHC) and real-time PCR in 40 clinical samples and in SKOV3 cells and SKOV3/TAX cells (paclitaxel-resistant human ovarian adenocarcinoma cell line). The effects of SOX2 knockdown on ovarian cancer cell proliferation, migration, and invasion were also studied. The IHC and real-time PCR results showed that the difference of SOX2 expression between ovarian cancer and the adjacent non-tumorous ovarian tissues was statistically significant. Western blot analysis revealed that the PI3K/Akt signaling pathway was inhibited in cells overexpressing SOX2. Western blot analysis showed that the SOX2 protein was overexpressed in paclitaxel-resistant cells and weakly detectable in paclitaxel-sensitive cells. SOX2 silencing significantly potentiated apoptosis induced by paclitaxel in SKOV3-TR with SOX2 knockdown compared to SKOV3-TR transfected with control small interfering RNA (siRNA). Our work indicates SOX2 will become both a rational indicator of ovarian cancer prognosis and a promising target for ovarian cancer gene therapy.

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.