Expression of Sox2 in human cervical carcinogenesis

Cancer stem cell biomarkers SOX2 and Oct4 in cervical cancer patients undergoing chemoradiotherapy

BACKGROUND

Cancer stem cell biomarkers SRY (sex-determining region Y)-box 2 (SOX2) and octamer-binding transcription factor 4 (Oct4) account for radioresistance in cervical squamous cell cancers (CSCCs). Their clinical implications are limited and contradictory.

METHODS

In this prospective cohort study, we recruited patients with FIGO IB2-IVA CSCC treated with primary chemoradiotherapy on regular follow-up. Tissue biopsy specimens were evaluated for SOX2 and Oct4 expression by immunohistochemistry, quantified by a product of proportion and intensity scores.

RESULTS

A total of 59 patients were included. Most had a moderately differentiated (81%), keratinizing (59%) CSCC, and ≥FIGO stage IIB disease (95%). SOX2 expression (high:low 21:38 patients) and Oct4 expression (high:low 4:55 patients) had a significant interrelation (p = 0.005, odds ratio (95% CI) - 1.23 (1.004-1.520)). At a median follow-up of 36 months, the 3-year overall survival (OS) was 60% and 53% for low and high SOX2 expression (p = 0.856), and 54% and 100% for low and high Oct4 expression (p = 0.114). The 3-year disease-frese survival (DFS) was 65% and 50% in the low and high SOX2 expression (p = 0.259), and 59% and 75% for low and high Oct4 expression (p = 0.598). SOX2 expression was the only variable significantly associated with a lower OS and DFS on regression analysis.

CONCLUSION

Our study demonstrated a trend toward improved OS and DFS with low SOX2 and high Oct4 expression in CSCC patients undergoing chemoradiotherapy.

Targeting Cervical Cancer Stem Cells by Phytochemicals

Cervical cancer (CaCx) poses a significant global health challenge, ranking as the fourth most common cancer among women worldwide. Despite the emergence of advanced treatment strategies, recurrence remains a bottleneck in favorable treatment outcomes and contributes to poor prognosis. The chemo- or radio-therapy resistance coupled with frequent relapse of more aggressive tumors are some key components that contribute to CaCx-related mortality. The onset of therapy resistance and relapse are attributed to a small subset of, slow-proliferating Cancer Stem Cells (CSC). These CSCs possess the properties of tumorigenesis, self-renewal, and multi-lineage differentiation potential. Because of slow cycling, these cells maintain themselves in a semi-quiescent stage and protect themselves from different anti-proliferative anti-cancer drugs. Keeping in view recent advances in their phenotypic and functional characterization, the feasibility of targeting CSC and associated stem cell signaling bears a strong translational value. The presence of CSC has been reported in CaCx (CCSC) which remains a forefront area of research. However, we have yet to identify clinically useful leads that can target CCSC. There is compelling evidence that phytochemicals, because of their advantages over synthetic anticancer drugs, could emerge as potential therapeutic leads to target these CCSCs. The present article examined the potential of phytochemicals with reported anti-CSC properties and evaluated their future in preclinical and clinical applications against CaCx.

Hsa_circ_0084912 Drives the Progression of Cervical Cancer Via Regulating miR-429/SOX2 Pathway

We focus on hsa_circ_0084912's role in Cervical cancer (CC) and its molecular pathways. In order to determine the expression of Hsa_circ_0084912, miR-429, and SOX2 in CC tissues and cells, Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) were utilized. Cell counting kit 8 (CCK-8), colony formation and Transwell assays were respectively to analyze CC cell proliferation viability, clone formation ability and migration. RNA immunoprecipitation (RIP) assay and dual-luciferase assay were used to assure the targeting correlation among hsa_circ_0084912/SOX2 and miR-429. By using a xenograft tumor model, the hsa_circ_0084912 impact on CC cell proliferation in vivo was confirmed. Hsa_circ_0084912 and SOX2 expressions were aggrandized, however, miR-429 expression was descended in CC tissues and cells. Silencing hsa_circ_0084912 inhibited cell proliferation, colony formation and migration in vitro of CC, meanwhile reducing growth of tumor in vivo. MiR-429 might be sponged by Hsa_circ_0084912 to control SOX2 expression. Hsa_circ_0084912 knockdown impact on the malignant phenotypes of CC cells was restored by miR-429 inhibitor. Moreover, SOX2 silencing eliminated the promotive effects of miR-429 inhibitors on CC cell malignancies. By raising SOX2 expression by targeting miR-429, hsa_circ_0084912 accelerated the development of CC, offering fresh proof that it is a viable target for CC treatment.

SOX2-associated signaling pathways regulate biological phenotypes of cancers

SOX2 is a transcription factor involved in multiple stages of embryonic development. In related reports, SOX2 was found to be abnormally expressed in tumor tissues and correlated with clinical features such as TNM staging, tumor grade, and prognosis in patients with various cancer types. In most cancer types, SOX2 is a tumor-promoting factor that regulates tumor progression and metastasis primarily by maintaining the stemness of cancer cells. In addition, SOX2 also regulates the proliferation, apoptosis, invasion, migration, ferroptosis and drug resistance of cancer cells. However, SOX2 acts as a tumor suppressor in some cases in certain cancer types, such as gastric and lung cancer. These key regulatory functions of SOX2 involve complex regulatory networks, including protein-protein and protein-nucleic acid interactions through signaling pathways and noncoding RNA interactions, modulating SOX2 expression may be a potential therapeutic strategy for clinical cancer patients. Therefore, we sorted out the phenotypes related to SOX2 in cancer, hoping to provide a basis for further clinical translation.

Capability of Human Dendritic Cells Pulsed with Autologous Induced Pluripotent Stem Cell Lysate to Induce Cytotoxic T Lymphocytes against HLA-A33-Matched Cancer Cells

Irradiated murine induced-pluripotent stem cells (iPSCs) elicit the antitumor response in vivo. However, it is unclear whether human iPSCs would elicit antitumor effects. In the present study, we investigated the capability of human iPSC lysate (iPSL)-pulsed dendritic cells (DCs) (iPSL/DCs) to induce cancer-responsive cytotoxic T lymphocytes (CTLs) in vitro. iPSCs and DCs were induced from peripheral blood mononuclear cells isolated from a human leukocyte antigen (HLA)-A33 homozygous donor. The iPSL was pulsed with immature DCs, which were then stimulated to allow full maturation. The activated DCs were co-cultured with autologous CTLs and their responses to SW48 colorectal carcinoma cells (HLA-A32/A33), T47D breast cancer cells (HLA-A33/A33), and T98G glioblastoma cells (HLA-A02/A02) were tested with enzyme-linked immunospot (ELISPOT) assays. Comprehensive gene expression analysis revealed that the established iPSCs shared numerous tumor-associated antigens with the SW48 and T47D cells. Immunofluorescent analysis demonstrated that the fluorescent-labeled iPSL was captured by the immature DCs within 2 h. iPSL/DCs induced sufficient CTL numbers in 3 weeks for ELISPOT assays, which revealed that the induced CTLs responded to SW48 and T47D cells. Human iPSL/DCs induced cancer-responsive CTLs on HLA-A33-matched cancer cells in vitro and could be a promising universal cancer vaccine for treating and preventing cancer.

SOX2 Promotes Invasion in Human Bladder Cancers through MMP2 Upregulation and FOXO1 Downregulation

SOX2, a member of the SRY-related HMG-box (SOX) family, is abnormally expressed in many tumors and associated with cancer stem cell-like properties. Previous reports have shown that SOX2 is a biomarker for cancer stem cells in human bladder cancer (BC), and our most recent study has indicated that the inhibition of SOX2 by anticancer compound ChlA-F attenuates human BC cell invasion. We now investigated the mechanisms through which SOX2 promotes the invasive ability of BC cells. Our studies revealed that SOX2 promoted SKP2 transcription and increased SKP2-accelerated Sp1 protein degradation. As Sp1 is a transcriptionally regulated gene, HUR transcription was thereby attenuated, and, in the absence of HUR, FOXO1 mRNA was degraded fast, which promoted BC cell invasion. In addition, SOX2 promoted BC invasion through the upregulation of nucleolin transcription, which resulted in increased MMP2 mRNA stability and expression. Collectively, our findings show that SOX2 promotes BC invasion through both SKP2-Sp1-HUR-FOXO1 and nucleolin-MMP2 dual axes.

Aberrant transcription factors in the cancers of the pancreas

Transcription factors (TFs) are essential for proper activation of gene set during the process of organogenesis, differentiation, lineage specificity. Reactivation or dysregulation of TFs regulatory networks could lead to deformation of organs, diseases including various malignancies. Currently, understanding the mechanism of oncogenesis became necessity for the development of targeted therapeutic strategy for different cancer types. It is evident that many TFs go awry in cancers of the pancreas such as pancreatic ductal adenocarcinoma (PDAC) and pancreatic neuroendocrine neoplasms (PanNENs). These mutated or dysregulated TFs abnormally controls various signaling pathways in PDAC and PanNENs including RTK, PI3K-PTEN-AKT-mTOR, JNK, TGF-β/SMAD, WNT/β-catenin, SHH, NOTCH and VEGF which in turn regulate different hallmarks of cancer. Aberrant regulation of such pathways have been linked to the initiation, progression, metastasis, and resistance in pancreatic cancer. As of today, a number of TFs has been identified as crucial regulators of pancreatic cancer and a handful of them shown to have potential as therapeutic targets in pre-clinical and clinical settings. In this review, we have summarized the current knowledge on the role and therapeutic usefulness of TFs in PDAC and PanNENs.

Prognostic utility of SOX2, STAT3, and CD44high/CD24low expression in penile cancer

PURPOSE

Penile cancer has a high incidence in developing countries. The standard treatment is removal of the primary tumor and, when necessary, inguinal lymphadenectomy. Currently, the most important prognostic factor is lymph node disease, however, the available staging methods are inaccurate, and the high morbidity rate of lymphadenectomy has stimulated the study of predictive biomarkers of lymph node metastasis for selecting the patients who need lymphadenectomy. SOX2, STAT3 and CD44^high/CD24^low were chosen because they have provided good predictive results in other squamous cell carcinoma (SCC), although there are no studies for penile cancer. Thus, the expression of SOX2, STAT3, CD24+, and CD44+ in the penile cancer tumor microenvironment was investigated for correlation with tumor behavior in SCC.

METHODS

This observational, prospective, translational study included 34 men and investigated the expression of SOX2, STAT3, CD24+, and CD44+ in tumor tissue by flow cytometry.

RESULTS

The median age of the 38 evaluated patients with penile cancer was 61 (37-80) years. Most patients presented a tumor located on the glans penis (82.3%), with the usual histological type (79.4%) and 61.7% of patients presented stage pT2. No metastasis was found in 85.3% of patients. The expression of SOX2, STAT3 and CD44^high/CD24^low in the microenvironment of penile SCC treated with lymphadenectomy was significantly associated with aggressive tumor behavior (p < 0.05). STAT3 expression shows discrepant points when evaluated in context of angiolymphatic vascular invasion.

CONCLUSION

SOX2, STAT3 and CD44^high/CD24^low in penile SCC can be indicators of prognosis, allowing for selection of more aggressive treatment when necessary.

SOX2 mediates metabolic reprogramming of prostate cancer cells

New strategies are needed to predict and overcome metastatic progression and therapy resistance in prostate cancer. One potential clinical target is the stem cell transcription factor SOX2, which has a critical role in prostate development and cancer. We thus investigated the impact of SOX2 expression on patient outcomes and its function within prostate cancer cells. Analyses of SOX2 expression among a case-control cohort of 1028 annotated tumor specimens demonstrated that SOX2 expression confers a more rapid time to metastasis and decreased patient survival after biochemical recurrence. SOX2 ChIP-Seq analyses revealed SOX2-binding sites within prostate cancer cells which differ significantly from canonical embryonic SOX2 gene targets, and prostate-specific SOX2 gene targets are associated with multiple oncogenic pathways. Interestingly, phenotypic and gene expression analyses after CRISPR-mediated deletion of SOX2 in castration-resistant prostate cancer cells, as well as ectopic SOX2 expression in androgen-sensitive prostate cancer cells, demonstrated that SOX2 promotes changes in multiple metabolic pathways and metabolites. SOX2 expression in prostate cancer cell lines confers increased glycolysis and glycolytic capacity, as well as increased basal and maximal oxidative respiration and increased spare respiratory capacity. Further, SOX2 expression was associated with increased quantities of mitochondria, and metabolomic analyses revealed SOX2-associated changes in the metabolism of purines, pyrimidines, amino acids and sugars, and the pentose phosphate pathway. Analyses of SOX2 gene targets with central functions metabolism (CERK, ECHS1, HS6SDT1, LPCAT4, PFKP, SLC16A3, SLC46A1, and TST) document significant expression correlation with SOX2 among RNA-Seq datasets derived from patient tumors and metastases. These data support a key role for SOX2 in metabolic reprogramming of prostate cancer cells and reveal new mechanisms to understand how SOX2 enables metastatic progression, lineage plasticity, and therapy resistance. Further, our data suggest clinical opportunities to exploit SOX2 as a biomarker for staging and imaging, as well as a potential pharmacologic target.

SOX2 expression in the pathogenesis of premalignant lesions of the uterine cervix: its histo-topographical distribution distinguishes between low- and high-grade CIN

SOX2 expression in high-grade cervical intraepithelial neoplasia (CIN3) and cervical squamous cell carcinoma is increased compared to that in the normal cervical epithelium. However, data on the expression and histological distribution of SOX2 in squamous epithelium during progression of CIN are largely lacking. We studied SOX2 expression throughout the epithelium in 53 cases of CIN1, 2, and 3. In general, SOX2 expression increased and expanded from basal/parabasal to the intermediate/superficial compartment during early stages of progression of CIN. An unexpected, specific expression pattern was found in areas classified as CIN2 and CIN3. This pattern was characterized by the absence or low expression of SOX2 in the basal/parabasal compartment and variable levels in the intermediate and superficial compartments. It was significantly associated with CIN3 (p = 0.009), not found in CIN1 and only seen in part of the CIN2 lesions. When the different patterns were correlated with the genetic make-up and presence of HPV, the CIN3-related pattern contained HPV-positive cells in the basal/parabasal cell compartment that were disomic. This is in contrast to the areas exhibiting the CIN1 and CIN2 related patterns, which frequently exhibited aneusomic cells. Based on their SOX2 localisation pattern, CIN1 and CIN2 could be delineated from CIN3. These data shed new light on the pathogenesis and dynamics of progression in premalignant cervical lesions, as well as on the target cells in the epithelium for HPV infection.

SOX2 as a prognostic marker and a potential molecular target in cervical cancer: A meta-analysis

BACKGROUND

Sex determining region Y-box 2 (SOX2) has been reported as a potential therapeutic target for cancer. However, the role of SOX2 in cervical cancer remains largely undetermined. This study was performed to evaluate the correlation of SOX2 with clinical characteristics and prognosis in cervical cancer.

METHODS

Multiple databases were systematically searched for eligible publications. The combined odds ratios (ORs) or hazard ratios (HRs) with the corresponding 95% confidence intervals (CIs) were used to assess the effect sizes.

RESULTS

A total of 17 studies with 1906 participants were identified. SOX2 expression was higher in cervical cancer than in the normal control group (OR = 10.83, 95% CI = 6.64-17.67, P < 0.001), while no significant difference was observed between cervical cancer and cervical intraepithelial neoplasia. SOX2 expression was not associated with age, tumor stage, and lymph node metastasis, but was correlated with tumor grade (grade 2-3 vs. grade 1: OR = 4.59, 95% CI = 2.76-7.62, P < 0.001) and tumor size (≥4 cm vs. ≤4 cm: OR = 1.66, 95% CI = 1.05-2.60, P = 0.028). Based on multivariate Cox analysis, SOX2 expression was not correlated with overall survival, but was closely associated with poor recurrence-free survival (HR = 5.83, 95% CI = 1.35-25.16, P = 0.018) and progress-free survival HR = 2.29, 95% CI = 1.01-5.19, P = 0.046).

CONCLUSION

SOX2 may serve as a novel prognostic factor and a promising molecular target for cervical cancer.

Cervical cancer progression is regulated by SOX transcription factors: Revealing signaling networks and therapeutic strategies

Cervical cancer is the fourth common gynecologic cancer and is considered as second leading cause of death among women. Various strategies are applied in treatment of cervical cancer including radiotherapy, chemotherapy and surgery. However, cervical cancer cells demonstrate aggressive behavior in advanced phases, requiring novel strategies in their elimination. On the other hand, SOX proteins are transcription factors capable of regulating different molecular pathways and their expression varies during embryogenesis, disease development and carcinogenesis. In the present review, our aim is to reveal role of SOX transcription factors in cervical cancer. SOX transcription factors play like a double-edged sword in cancer. For instance, SOX9 possesses both tumor-suppressor and tumor-promoting role in cervical cancer. Therefore, exact role of each SOX members in cervical cancer has been discussed to direct further experiments for revealing other functions. SOX proteins can regulate proliferation and metastasis of cervical cancer cells. Furthermore, response of cervical cancer cells to chemotherapy and radiotherapy is tightly regulated by SOX transcription factors. Different downstream targets of SOX proteins such as Wnt signaling, EMT and Hedgehog have been identified. Besides, upstream mediators such as microRNAs, lncRNAs and circRNAs can regulate SOX expression in cervical cancer. In addition to pre-clinical studies, role of SOX transcription factors as prognostic and diagnostic tools in cervical cancer has been shown.

Synthesis and Characterization of Salinomycin-Loaded High-Density Lipoprotein and Its Effects on Cervical Cancer Cells and Cervical Cancer Stem Cells

Background

Cervical cancer stem cells (CCSCs), a small part of tumor population, are one of the important reasons for metastasis and recurrence of cervical cancer. Targeting CCSCs may be an effective way to eliminate tumors. Salinomycin (Sal) has been proved to be an effective anticancer drug in many studies, especially for cancer stem cells (CSCs). However, the cytotoxicity of salinomycin limits its further research as an anticancer drug. High-density lipoprotein (HDL) nanoparticles are an excellent drug carrier, which can reduce the toxicity of Sal, have a certain targeting effect and improve the clinical benefit of Sal.

Methods

Salinomycin-loaded high-density lipoprotein (S-HDL) was synthesized and characterized by various analytical techniques. CD44^highCD24^low CCSCs were isolated from HeLa cells by magnetic separation. The uptake of HDL nanoparticles was observed by laser confocal microscopy, and the effect of S-HDL on the proliferation of CCCs and CCSCs was detected by cell viability analysis. Genome-wide analysis was used to analyze the effects of S-HDL on the biological processes of CCCs and then cell apoptosis, cell cycle and cell migration were selected for verification.

Results

S-HDL had a particle size of 38.98 ± 1.78 nm and an encapsulation efficiency of 50.73 ± 4.29%. Cell uptake analysis showed that HDL nanoparticles could enhance the drug uptake of CCCs and CCSCs and may target CCCs and CCSCs. In cell viability analysis, CCCs and CCSCs showed high sensitivity to S-HDL. S-HDL can more efficiently prevent CCSCs from developing tumorspheres than Sal in tumorsphere formation study. S-HDL had stronger ability to induce cell cycle arrest, promote cell apoptosis and inhibit cell migration compared with free Sal, which was consistent with the results of Genome Wide analysis.

Conclusion

S-HDL can effectively target and eliminate CCCs and CCSCs, which is a potential drug for the treatment of cervical cancer.

Establishment of a Plasticity-Associated Risk Model Based on a SOX2- and SOX9-Related Gene Set in Head and Neck Squamous Cell Carcinoma

Recent studies highlighted SOX2 and SOX9 as key determinants for cancer-cell plasticity and demonstrated that cisplatin-induced adaptation in oral squamous cell carcinoma (SCC) is acquired by an inverse regulation of both transcription factors. However, the association between SOX2/SOX9-related genetic programs with risk factors and genetic or epigenetic alterations in primary head and neck SCC (HNSCC), and their prognostic value is largely unknown.Here, we identified differentially-expressed genes (DEG) related to SOX2 and SOX9 transcription in The Cancer Genome Atlas (TCGA)-HNSC, which enable clustering of patients into groups with distinct clinical features and survival. A prognostic risk model was established by LASSO Cox regression based on expression patterns of DEGs in TCGA-HNSC (training cohort), and was confirmed in independent HNSCC validation cohorts as well as other cancer cohorts from TCGA. Differences in the mutational landscape among risk groups of TCGA-HNSC demonstrated an enrichment of truncating NSD1 mutations for the low-risk group and elucidated DNA methylation as modulator of SOX2 expression. Gene set variation analysis (GSVA) revealed differences in several oncogenic pathways among risk groups, including upregulation of gene sets related to oncogenic KRAS signaling for the high-risk group. Finally, in silico drug screen analysis revealed numerous compounds targeting EGFR signaling with significantly lower efficacy for cancer cell lines with a higher risk phenotype, but also indicated potential vulnerabilities. IMPLICATIONS: The established risk model identifies patients with primary HNSCC, but also other cancers at a higher risk for treatment failure, who might benefit from a therapy targeting SOX2/SOX9-related gene regulatory and signaling networks.

Identification of Chemo and Radio-Resistant Sub-Population of Stem Cells in Human Cervical Cancer HeLa Cells

BACKGROUND

Cervical cancer ranks the second female malignancy after breast cancer. Cancer stem cells (CSCs) are hard to be eradicated, so can recur. We aim to isolate and characterize CSCs from HeLa cells.

METHODS

These cells express clusters of differentiation (CDs), 44 and 24, to be sorted by fluorescence-activated cell sorting (FACS).

RESULTS

CD44⁺CD24⁺ cells showed potential to form spheres, tumorigenicity, stemness genes and higher resistance to cisplatin, X-ray.

CONCLUSION

CD44⁺CD24⁺ HeLa cells hold characteristics of CSCs, in vitro, in vivo studies, suggesting that targeting may lead to screening of new anti-cancer therapies.

PHF20 inhibition promotes apoptosis and cisplatin chemosensitivity via the OCT4‑p‑STAT3‑MCL1 signaling pathway in hypopharyngeal squamous cell carcinoma

Cisplatin is a widely used platinum‑based chemotherapeutic agent for hypopharyngeal squamous cell carcinoma (HSCC). However, resistance to cisplatin limits its use for the treatment of HSCC, and the underlying molecular mechanism requires further investigation. The present study performed functional assays to determine whether the expression of plant homeodomain finger protein 20 (PHF20) may be involved in the apoptosis and cisplatin resistance of HSCC. The expression levels of PHF20 were higher in cisplatin‑resistant HSCC cells compared with those in cisplatin‑sensitive cells. The inhibition of PHF20 suppressed cell viability but did not affect the migratory and invasive abilities of HSCC cells compared with those of negative control‑transfected cells. Furthermore, PHF20 inhibition reduced cell viability by enhancing apoptosis compared with those in the control cells in vitro. Notably, the inhibition of PHF20 sensitized HSCC cells to cisplatin, thus increasing apoptosis via the signal transducer and activator of transcription 3 (STAT3)‑myeloid cell leukemia‑1 (MCL1) pathway. Octamer‑binding transcription factor 4 (OCT4) overexpression restored phosphorylated STAT3‑MCL1‑mediated apoptosis induced by PHF20 inhibition. In vivo experiments confirmed that PHF20 silencing induced tumor growth and increased apoptosis in HSCC cells compared with those in the control cells. Thus, PHF20 inhibition may promote apoptosis and improve cisplatin chemosensitivity via the OCT4‑p‑STAT3‑MCL1 signaling pathway in HSCC.

BRM270 Suppresses Cervical Cancer Stem Cell Characteristics and Progression by Inhibiting SOX2

BACKGROUND/AIM

Cervical cancer is one of the leading causes of cancer death in women worldwide. BRM270 (BRMLife) has therapeutic potential for cancer treatment owing to its ability to inhibit cell proliferation, and expression of cluster of differentiation (CD) 133 in CD133⁺ cancer cells. This study was designed to evaluate the therapeutic effects of plant extract formulation BRM270 against cervical cancer progression.

MATERIALS AND METHODS

The expression of sex-determining region Y-box 2 (SOX2) was tested in four different cervical cancer cell lines, HeLA, SiHa, Caski and C33A. SOX2-expressing SiHa and C33A cell lines were selected for further experiments on the in vitro and in vivo effects of BRM270 on cervical cancer progression using western blotting, flow cytometry, sphere-formation assay, magnetic-activated cell sorting of CD133⁺ cervical cancer cells, and xenografts in female athymic BALB/c nude mice.

RESULTS

In the present study, in cervical cancer stem cells (CSCs), we found that BRM270 inhibited expression of SOX2, which is associated with cervical cancer initiation and metastasis. BRM270 also inhibited CD133 expression and induced apoptosis of CSCs and suppressed CD133⁺ CSC proliferation and sphere formation in vitro as well as SiHa and C33A cell xenograft tumor growth in vivo. This was accompanied by down-regulation of markers of epithelial-to-mesenchymal transition.

CONCLUSION

BRM270 might be an effective agent for cervical cancer treatment.

SOX2 Regulates lncRNA CCAT1/MicroRNA-185-3p/FOXP3 Axis to Affect the Proliferation and Self-Renewal of Cervical Cancer Stem Cells

It has been presented the role of long non-coding RNAs (lncRNAs) in cervical cancer (CC). We aim to discuss the effect of sex-determining region Y-box 2 (SOX2)/lncRNA colon cancer-associated transcript-1 (CCAT1)/microRNA-185-3p (miR-185-3p)/forkhead box protein 3 (FOXP3) on the proliferation and self-renewal ability of CC stem cells. MiR-185-3p, SOX2, CCAT1 and FOXP3 expressions were tested in CC tissues and cells. The relationship between SOX2/CCAT1 expression and clinicopathological features in CC patients was verified. Loss- and gain-of-function investigations were conducted in CD44⁺HeLa cells to discuss biological functions and self-renewal capacity. Finally, the relationships among SOX2, CCAT1, FOXP3 and miR-185-3p were verified. miR-185-3p expression was decreased, while SOX2, CCAT1 and FOXP3 expressions were increased in CC tissues and cells. SOX2 and CCAT1 expressions were linked to tumor size, lymph node metastasis and international federation of gynecology and obstetrics stage of CC. Down-regulating SOX2 or CCAT1 and up-regulating miR-185-3p resulted in inhibition of proliferation, invasion, migration and cell sphere number as well as apoptosis acceleration of CD44⁺HeLa cells. SOX2 could bind to CCAT1 which affected miR-185-3p expression, and FOXP3 was targeted by miR-185-3p.

Molecular landscape of recurrent cervical cancer

Cervical cancer (CC) is a major gynecological problem in developing and underdeveloped countries. Despite the significant advancement in early detection and treatment modalities, several patients recur. Moreover, the molecular mechanisms responsible for CC recurrence remains obscure. The patients with CC recurrence often show poor prognosis and significantly high mortality rates. The clinical management of recurrent CC depends on treatment history, site, and extent of the recurrence. Owing to poor prognosis and limited treatment options, recurrent CC often presents a challenge to the clinicians. Several in vitro, in vivo, and patient studies have led to the identification of the critical molecular changes responsible for CC recurrence. Both aberrant genetic and epigenetic modifications leading to altered cell signaling pathways have been reported to impact CC recurrence. Researchers are currently trying to dissect the molecular pathways in CC and translate these findings for better management of disease. This article attempts to review the existing knowledge of disease relapse, accompanying challenges, and associated molecular players in CC.

NF-YA promotes the cell proliferation and tumorigenic properties by transcriptional activation of SOX2 in cervical cancer

NF‐YA is considered as a crucial regulator for the maintenance of cancer stem cell (CSC) and involved in various types of malignant tumours. However, the exact function and molecular mechanisms of NF‐YA in the progression of cervical cancer remains poorly understood. Here, the expression of NF‐YA detected by immunohistochemistry was gradually increased from normal cervical tissues, to the high‐grade squamous intraepithelial lesions, and then to cervical cancer tissues. NF‐YA promoted the cell proliferation and tumorigenic properties of cervical cancer cells as well as tumorsphere formation and chemoresistance in vitro. The luciferase reporter assay combined with mutagenesis analyses and Western blotting showed that NF‐YA trans‐activated the expression of SOX2 in cervical cancer. Furthermore, quantitative chromatin immunoprecipitation (qChIP) and electrophoretic mobility shift assay (EMSA) confirmed that NF‐YA protein directly bound to the CCAAT box region located upstream of the SOX2 promoter. Together, our data demonstrated that NF‐YA was highly expressed in cervical cancer and promoted the cell proliferation, tumorigenicity and CSC characteristic by trans‐activating the expression of SOX2.

Switches of SOX17 and SOX2 expression in the development of squamous metaplasia and squamous intraepithelial lesions of the uterine cervix

AIMS

The dynamics and topographical distribution of SOX17 and SOX2 expression was studied in the transformation zone (TZ) of the uterine cervix. This TZ is a dynamic area where switches from glandular into squamous epithelium can be recognized, new squamocolumnar junctions are formed, and premalignant lesions originate. SOX17 and SOX2 show mutually exclusive expression patterns in the normal uterine cervix, with SOX2 being exclusively found in squamous epithelium, while SOX17 is detected in endocervical columnar cells and reserve cells.

METHODS AND RESULTS

Normal cervices and squamous intraepithelial lesions (SIL) were studied with immunohistochemistry, methylation of SOX17, human papilloma virus (HPV) genotyping, and in situ hybridization. In the TZ squamous metaplasia originating from these reserve cells can still show SOX17 expression, while also remnants of SOX17-positive immature metaplasia can be recognized in the normal squamous epithelium. SOX17 expression is gradually lost during maturation, resulting in the exclusive expression of SOX2 in the majority of (SIL). This loss of SOX17 expression is independent of methylation of the CpG island in its promotor region. HPV can be detected in SOX17-positive immature metaplastic regions in the immediate vicinity of SOX2-positive SIL, suggesting that switches in SOX17 and 2 expression can occur upon HPV infection.

CONCLUSIONS

This switch in expression, and the strong association between the distribution of reserve cells and squamous areas within the columnar epithelium in the TZ, suggests that reserve cell proliferations, next to basal cells in the squamous epithelium, are potential targets for the formation of squamous lesions upon viral infection.

Molecular characterization of AwSox2 from bivalve Anodonta woodiana: Elucidating its player in the immune response

Sox2 is an embryonal stem cell Ag essential for early embryonic development, tissue homeostasis and immune regulation. In the current study, one complete Sox2 cDNA sequence was cloned from freshwater bivalve Anodonta woodiana and named AwSox2. Histological changes of testis derived from Bisphenol A (BPA) treatment were analyzed by hematoxylin and eosin staining. Expressions of AwSox2 derived from BPA, LPS and polyinosinic:polycytidylic (Poly I:C) challenge were measured by quantitative real-time PCR. The full-length cDNA of AwSox2 contained an open reading frame of 927 nucleotides bearing the typical structural features of Sox2 family. Obvious degeneration, irregular arrangement of spermatids, and clotted dead and intertwined spermatids were observed in BPA-treated groups. Administration of BPA could result in a dose-dependent up-regulation of AwSox2 expression in the male gonadal tissue of A. woodiana. In addition, expression of AwSox2 was significantly induced by LPS and Poly I:C treatment in the hepatopancreas, gill and hemocytes, compared with that of control group. These results indicated that up-regulations of AwSOx2 are closely related to apoptosis of spermatogonial stem cells derived from BPA treatment as well as enhancement of immune defense against LPS and Poly I:C challenge in A. woodiana.

WIP1 promotes cancer stem cell properties by inhibiting p38 MAPK in NSCLC

Cancer stem cells (CSCs) are a small population of stem cell-like cancer cells that can initiate tumors in vivo, and are the major source of cancer initiation, relapse, and drug resistance. We previously reported that the p38 MAPK, through its downstream effectors MK2 and HSP27, suppressed CSC properties by downregulating the expression of transcription factors that mediate stemness in non-small-cell lung cancer (NSCLC) cells, and that despite unaltered total expression of total p38 proteins, the levels of activated p38 were reduced in NSCLC tissues. However, the mechanism underlying the reduced levels of activated p38 in NSCLC is unknown. In this study, we identified WIP1, a p38 phosphatase frequently overexpressed in cancer, as a suppressor of p38 in a pathway that regulates CSC properties in NSCLC. Increased WIP1 expression correlated with reduced levels of activated p38, and with increased levels of a CSC marker in NSCLC tissues. Further investigation revealed that WIP1 promoted stemness-related protein expression and CSC properties by inhibiting p38 activity in NSCLC cells. WIP1 inhibitors are currently under development as anticancer drugs based on their ability to reactivate p53. We found that a WIP1 inhibitor suppressed stemness-related protein expression and CSC properties by activating p38 in NSCLC cells in vitro and in vivo. These studies have identified the WIP1–p38–MK2–HSP27 cascade as a novel signaling pathway that, when altered, promotes CSC properties in NSCLC development, and have defined novel mechanisms underlying the oncogenic activity of WIP1 and the anticancer efficacy of WIP1 inhibitors.

LncRNA SOX2OT affects cervical cancer cell growth, migration and invasion by regulating SOX2

Long non-coding RNA (lncRNA) SOX2 overlapping transcript (SOX2OT) has been shown to play an oncogenic role in diverse cancers, generating eight transcript variants. SOX2 is located in the third intron of SOX2OT. However, the biological function of SOX2OT in cervical cancer and implication with SOX2 remain to be further explored. In this study, we screened the expression pattern of different SOX2OT transcript variants in cervical cancer cells. Interestingly, both high-expression levels of SOX2OT transcript 7 (SOX2OT-7) and SOX2 were detected in C-33A (HPV^-) and SiHa (HPV16⁺) cells. Thus, C-33A and SiHa cells were conducted to investigate the effects of SOX2OT on cell growth, migration and invasion. Finally, rescue experiments were performed to confirm the role of SOX2 in SOX2OT-mediated regulation of cervical cancer progression. The results showed that knockdown of SOX2OT suppressed cell viability, arrested cell cycle and ameliorated migration and invasion ability of C-33A and SiHa cells. Ectopic expression of SOX2OT-7 exacerbated cervical cancer cell proliferation, migration and invasion. In addition, we found that the expression levels and protein stability of SOX2 were positively regulated by SOX2OT. Inhibition of SOX2 could block the malignant phenotypes of C-33A and SiHa cells by SOX2OT-7. In conclusion, these findings indicate that lncRNA SOX2OT contributes to the growth, migration and invasion of cervical cancer cells by modulating SOX2. Importantly, we demonstrate that the transcript SOX2OT-7 may be a novel and promising biomarker for both HPV^- and HPV16⁺ cervical cancer.

Flow Cytometry Characterization of Pluripotent Transmembrane Glycoproteins on Resident Cervix Uteri Cells in Patients Screened for Cervical Cancer

The aim of this study was to characterize both by flow cytometry analysis and immunohistochemistry cervix uteri cells of nulliparous women screened for cervical intraepithelial neoplasia (CIN) in comparison to a group without CIN by using mesenchymal stem cell-like and hematopoietic lineage markers. A significant expression for CD29, CD38, HLA-I, and HLA-II was correlated positively to the CIN degree and it was more relevant in patients positive for human papilloma virus (HPV). Thus, identification and detailed characterization of pluripotent resident in uteri cells could be a promising therapeutic target.

Genes Involved in the Transcriptional Regulation of Pluripotency Are Expressed in Malignant Tumors of the Uterine Cervix and Can Induce Tumorigenic Capacity in a Nontumorigenic Cell Line

Transcription factors OCT4, SOX2, KLF4, C-MYC, and NANOG (OSKM-N) regulate pluripotency and stemness, and their ectopic expression reprograms human and murine fibroblasts that constitute the key of regenerative medicine. To determine their contribution to cell transformation, we analyzed the gene expression profiles of these transcription factors in cervical cancer samples and found that they are preferentially expressed in the tumor component. Also, cancer stem cell-enriched cultures grown as sphere cultures showed overexpression of OSKM-N genes. Importantly, we observed that lentiviral-mediated transduction of these factors confers, to a nontumorigenic immortalized human cell line, properties of cancer stem cells as the ability to form tumors in a mouse model. When we performed a meta-analysis using microarray data from cervical cancer biopsies and normal tissues, we found that the expression of OSKM-N and some target genes allowed separating tumor and normal tissues between samples, which enhanced the importance of OSKM-N in the tumorigenesis. Finally, we analyzed and compared both transcript and protein expression profiles of these factors within a cohort of patients with cervical cancer. To our knowledge, this is the first time that the expression of OSKM-N is described to induce one of the main characteristics of the cancer stem cell, the tumorigenicity. And, more importantly, its exogenous expression in a nontumorigenic cell line is sufficient to induce a tumorigenic phenotype; furthermore, the differential expression of this transcription factor distinguishes tumor tissue and normal tissue in cervical samples.

SOX17 expression and its down-regulation by promoter methylation in cervical adenocarcinoma in situ and adenocarcinoma

AIMS

SOX17 expression has not been studied in glandular lesions of the uterine cervix like adenocarcinoma in situ (AIS) and invasive adenocarcinomas (AdC), whereas SOX17 promoter CpG island methylation has been reported. Therefore, the aim of this study was to relate the topographical distribution of SOX17 expression and SOX17 methylation status to each other, and to SOX2 expression, human papillomavirus (HPV) type, and physical status of the virus.

METHODS AND RESULTS

Immunohistochemistry was used in 45 cases to assess expression of SOX17 and SOX2. SOX17 promoter methylation was determined in 25 cases by means of bisulphite conversion and methylation-specific polymerase chain reaction. SOX17 and SOX2 showed a mutually exclusive expression pattern in normal epithelium, with a sharp delineation in the squamocolumnar junction. SOX17 was found in endocervical columnar and reserve cells, whereas SOX2 was exclusively found in squamous epithelium. In both glandular lesions and cases with coexisting glandular and squamous intraepithelial components, a complex combination of SOX17 and SOX2 expression patterns was seen and mutually exclusive expression was lost. Frequently, gain of expression of SOX2 was found and expression of SOX17 was lost. Methylation of the CpG island in the SOX17 promoter was shown to be strongly associated with loss of expression of SOX17 (P = 0.0016).

CONCLUSIONS

In this study, we show for the first time a direct correlation between the topographical distribution of SOX17 expression and the methylation status of its gene promoter. This explains the heterogeneity of SOX17 expression in the glandular lesions of the cervix. No correlation was found between HPV type and physical status of the virus on the one hand and methylation status on the other.

Cancer stem cells in neuroblastoma therapy resistance

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

Impact of modulation of telomerase and cancer stem-cell marker OCT4 axis in cervical cancer pathogenesis with underlying HPV16 infection

Lacunae exist in the molecular event(s) specificity associated with cervical cancer (CaCx) pathogenesis. The present study aimed to evaluate the significance of telomerase-cervical cancer stem cells (CSCs) modulation in CaCx pathogenesis with underlying HPV16 infection. The study included HPV16 positive cases only (N = 65) of the total enrolled cases from Northeast India. The analysis of viral load and the differential messenger RNA expression of E6, E7, hTERT, hTR, and cancer stem-cell markers was studied by real-time polymerase chain reaction. Further the protein and colocalization study for E6, hTERT, and oct4 was performed by immunofluorescence. The real-time polymerase chain reaction based analysis showed an upregulation of HPV16 viral oncoprotein E6 and E7, and telomerase component hTERT and hTR expression and their correlation in CaCx susceptibility and severity. The hTERT expression correlated with viral load; while the E6 and telomerase protein expression colocalized in the nucleus. The CSCs marker octamer-binding transcription factor 4 (OCT4) was significantly upregulated in CaCx cases, was associated with CaCx susceptibility and severity, and colocalized with E6 expression in the nucleus as revealed from the immunofluorescence studies. To conclude, the telomerase-OCT4 axis modulation holds key in HPV16 CaCx pathogenesis mediated by HPV16 E6 viral oncoprotein expression, and underlines its potential for therapeutic targeting.

Up-regulation of microRNA-200c-3p inhibits invasion and migration of renal cell carcinoma cells via the SOX2-dependent Wnt/β-catenin signaling pathway

Background

MicroRNA-200c-3p (miR-200c-3p) has been revealed to be related to renal cell carcinoma (RCC) progression, while the inner mechanisms remain unknown. In our study, we intend to unearth the capability of miR-200c-3p in RCC development via the Wnt/β-catenin signaling pathway through binding to SOX2.

Methods

miR-200c-3p, SOX2, β-catenin and GSK3β expression in both tissues and cells of RCC were detected by RT-qPCR or western blot analysis. miR-200c-3p was restored or silenced to determine their biological functions of RCC cells. Expression of SOX2 and related proteins in the Wnt/β-catenin signaling pathway were evaluated by RT-qPCR and western blot analysis. The effect of the combination of downregulated miR-200c-3p and downregulated SOX2 on cell biological behavior change was also determined.

Results

Initially, we found that miR-200c-3p was declined while SOX2, β-catenin and GSK3β was elevated in RCC tissues and cells. A498 cells with the largest difference in miR-200c-3p expression and OS-RC-2 cells with the smallest difference were selected for subsequent experiments. Additionally, upregulated miR-200c-3p and downregulated SOX2 was determined to suppress proliferation, migration, invasion and induce apoptosis of RCC cells. Furthermore, miR-200c-3p inhibited SOX2 to inactivate the Wnt/β-catenin signaling pathway.

Conclusion

Collectively, this study highlights that upregulated miR-200c-3p inhibits expression of SOX2, thereby inhibiting development of RCC cells via modulating the Wnt/β-catenin signaling pathway activation.

Induced Pluripotent Stem Cell-Based Cancer Vaccines

Over a century ago, it was reported that immunization with embryonic/fetal tissue could lead to the rejection of transplanted tumors in animals. Subsequent studies demonstrated that vaccination of embryonic materials in animals induced cellular and humoral immunity against transplantable tumors and carcinogen-induced tumors. Therefore, it has been hypothesized that the shared antigens between tumors and embryonic/fetal tissues (oncofetal antigens) are the key to anti-tumor immune responses in these studies. However, early oncofetal antigen-based cancer vaccines usually utilize xenogeneic or allogeneic embryonic stem cells or tissues, making it difficult to tease apart the anti-tumor immunity elicited by the oncofetal antigens vs. graft-vs.-host responses. Recently, one oncofetal antigen-based cancer vaccine using autologous induced pluripotent stem cells (iPSCs) demonstrated marked prophylactic and therapeutic potential, suggesting critical roles of oncofetal antigens in inducing anti-tumor immunity. In this review, we present an overview of recent studies in the field of oncofetal antigen-based cancer vaccines, including single peptide-based cancer vaccines, embryonic stem cell (ESC)- and iPSC-based whole-cell vaccines, and provide insights on future directions.

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

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

Aberrantly elevated Bmi1 promotes cervical cancer tumorigenicity and tumor sphere formation via enhanced transcriptional regulation of Sox2 genes

The exact molecular mechanisms underlying cervical tumorigenesis are poorly understood. Polycomb complex protein Bmi1 (Bmi1) is involved in the malignant transformation and biological aggressiveness of several human carcinomas. Therefore, the present study assessed the expression of Bmi1 protein in human cervical cancer tissues and examined the mechanisms involved in cervical carcinogenesis. The expression of Bmi1 protein was examined by immunohistochemistry in cervical carcinoma tissues (n=71), high-grade squamous intraepithelial lesions (n=41) and normal cervical tissues (n=47). Expression of Bmi1 protein gradually increased across samples from the normal cervix (1/47; 2.12%), high-grade squamous intraepithelial lesions (5/42; 16.13%) and cervical carcinomas (31/71; 43.66%; P<0.05). Additionally, Bmi1 protein expression was associated with tumor histopathological grade. The effects of Bmi1 silencing and overexpression on tumor sphere formation and the tumorigenicity of cervical cancer cells were investigated. Overexpression of Bmi1 resulted in significantly attenuated tumor formation and tumor sphere formation. Consistently, Bmi1 silencing significantly inhibited tumor formation and tumor sphere formation. Furthermore, Bmi1 upregulated the expression of Sox2, and the dual-luciferase reporter assay and chromatin immunoprecipitation showed that Bmi1 transactivated Sox2 by binding to the two E-box motifs in the Sox2 promoter. In conclusion, aberrantly elevated Bmi1 promotes cervical cancer tumorigenicity and tumor sphere formation via enhanced transcriptional regulation of Sox2 genes as a potential oncogenic factor that participates in the carcinogenesis of cervical carcinomas.

Potential role of cancer stem cells as biomarkers and therapeutic targets in cervical cancer

BACKGROUND

Eradicating cancer stem cells (CSCs) that are termed as the "beating heart" of various malignant tumors, including cervical cancer, holds great importance in cancer therapeutics. CSCs not only confer chemo-radio resistance but also play an important role in tumor metastasis and thereby pose a potential barrier for the cure of cervical cancer. Cervical cancer, a common malignancy among females, is associated with high morbidity and mortality rates, and the study on CSCs residing in the niche is promising.

RECENT FINDINGS

Biomarker approach to screen the cervical CSCs has gained impetus since the past decade. Progress in identification and characterization of the stem cell biomarkers has led to many insights. For the diagnostic purpose, several biomarkers like viral (HPV16), stem cell markers, transcription factors (viz, SOX2, OCT 4, and c-Myc), and CSC surface markers (viz, ALDH1 and CD44) have been identified. The research so far has been directed to study the CSC stemness and demonstrates various gene expression signatures in cervical CSCs. Such studies hold a potential to improve diagnostic accuracy and predict therapeutic response and clinical outcome in patients.

CONCLUSIONS

Stem cell biomarkers have been validated and their therapeutic targets are being developed as "strategies to improve therapeutic ratio in personalized medicine." This review gives a brief overview of the cervical CSC biomarkers, their current and future diagnostic, prognostic, and therapeutic potential.

Bioinformatics Analysis Makes Revelation to Potential Properties on Regulation and Functions of Human Sox2

Sex determining region Y-box 2 (Sox2) is a transcription factor that is essential for maintaining self-renewal or pluripotency of undifferentiated embryonic stem cells. The expression and distribution of Sox2 in tumor tissues have been extensively recorded, which are related to the progression and metastasis of tumor. However, a complete mechanistic understanding of Sox2 regulation and function remains to be studied. Herein, we show new potential properties of Sox2 regulation and functions from bioinformatics analysis. We use numerous algorithms to characterize the Sox2 gene promoter elements and the Sox2 protein structure, physio-chemical, localization properties and its evolutionary relationships. The expression of Sox2 is regulated by a diverse set of transcription factors and associated with the levels of methylation of CpG Islands in promoters. The structural properties of Sox2 indicate that Sox2 expresses as a stem cell marker in a variety of stem cells. Sox2 together with other transcription factors or proteins regulate the expression of downstream target genes, which makes a great difference to the biological function of stem cells. Not only stem cells, Sox2 also play an important role in tumor cells. In conclusion, this information from bioinformatics analysis will help to understand Sox2 regulation and functions better in future attempts.

SOX2 regulates radioresistance in cervical cancer via the hedgehog signaling pathway

OBJECTIVE

Resistance to radiotherapy accounts for most treatment failures in cervical cancer patients who receive radical radiation therapy. To discover the possible mechanism of radioresistance and improve the 5-year survival rate, we focused on how sex-determining region Y-box 2 (SOX2) mediates radioresistance in cervical cancer as well as on the interaction between SOX2 and the hedgehog (Hh) signaling pathway in this study.

METHODS

We established the acquired radioresistant subclone cells Hela-RR and Siha-RR. RT-qPCR, Western blot analysis, IHC, clonogenic survival assay, CCK-8 assay, apoptosis analysis, cell cycle analysis and xenograft models were used to explore the relationship between SOX2 expression and radiation resistance and to determine how SOX2 mediates radioresistance in cervical cancer. Furthermore, luciferase reporter and ChIP-PCR assays were utilized to assess the interaction between SOX2 and the Hh signaling pathway.

RESULTS

Our research suggested that high expression of SOX2 was responsible for radioresistance in cervical cancer. SOX2 was observed to be closely related to irradiation-induced survival, proliferation, apoptosis, and cell cycle changes. The Hh signaling pathway was found to be activated in Hela-RR and Siha-RR, and the activation changed with SOX2 expression. IHC staining of SOX2 and Gli1 showed a close relationship between SOX2 and the Hh pathway. Luciferase reporter and ChIP-PCR assays demonstrated that SOX2 interacted with the Hh signaling pathway by occupying the HHAT promoter.

CONCLUSIONS

SOX2 is a potential therapeutic target of irradiation resistance in cervical cancer. It mediates radioresistance in cervical cancer via the Hh signaling pathway.

Human endogenous retroviruses role in cancer cell stemness

Cancer incidence and mortality, metastasis, drug resistance and recurrence are still the critical issues of oncological diseases. In this scenario, increasing scientific evidences demonstrate that the activation of human endogenous retroviruses (HERVs) is involved in the aggressiveness of tumors such as melanoma, breast, germ cell, renal, ovarian, liver and haematological cancers. In their dynamic regulation, HERVs have also proved to be important determinants of pluripotency in human embryonic stem cells (ESC) and of the reprogramming process of induced pluripotent stem cells (iPSCs). In many types of tumors, essential characteristics of aggressiveness have been associated with the achievement of stemness features, often accompanied with the identification of defined subpopulations, termed cancer stem cells (CSCs), which possess stem cell-like properties and sustain tumorigenesis. Indeed, CSCs show high self-renewal capacity with a peculiar potential in tumor initiation, progression, metastasis, heterogeneity, recurrence, radiotherapy and drug resistance. However, HERVs role in CSCs biology is still not fully elucidated. In this regard, CD133 is a widely recognized marker of CSCs, and our group demonstrated, for the first time, the requirement of HERV-K activation to expand and maintain a CD133+ melanoma cell subpopulation with stemness features in response to microenvironmental modifications. The review will discuss HERVs expression as cancer hallmark, with particular focus on their role in the regulation of cancer stemness features and the potential involvement as targets for therapy.

Low P16INK4A Expression Associated with High Expression of Cancer Stem Cell Markers Predicts Poor Prognosis in Cervical Cancer after Radiotherapy

Previous studies have suggested that cancer stem cells (CSCs) resisted radiotherapy and chemotherapy. P16^INK4A is a biomarker for cervical carcinogenesis and reduces proliferation of stem cells. We aimed to investigate the expression and clinical significance of cyclin-dependent kinase inhibitor 2A (P16^INK4A), sex determining region Y-box 2 (SOX2), and Aldehyde dehydrogenase 1 family, member A1 (ALDH1A1) in cervical cancer treated with radiotherapy and cervical cell line models. The expressions of P16^INK4A, SOX2, and ALDH1A1 were performed by immunohistochemical staining of tumor samples from 139 cervical cancer patients with International Federation of Gynecology and Obstetrics stages Ib to IV. The staining showed high expression in 100, 107, and 13 patients with P16^INK4A (>80%), SOX2 (≥10%), and ALDH1A1 (50%), respectively. The high-P16^INK4A group had a higher five-year overall survival (OS) rate and disease-free survival (DFS) than the low-P16^INK4A group (OS: 62.0% and 35.2%, p = 0.016; DFS: 60.0% and 31.2%, p = 0.002). The low-P16^INK4A/high-SOX2 and low-P16^INK4A/high-ALDH1A1 groups had a worse five-year OS and DFS rate than the high-P16^INK4A/low-SOX2 and high-P16^INK4A/low-ALDH1A1 groups, respectively. Depletion of P16^INK4A promoted chemoresistance and radioresistance of cervical cancer cells increased the expression of SOX2 and ALDH1A1 and exhibited higher self-renewal ability. These results suggest that lower P16^INK4A expression associated with higher CSC markers predicts poor prognostic outcomes and is a promising target in patients with cervical cancer.

Podoplanin and SOX2 Expression in CIN 3-like Squamous Cell Carcinoma of the Cervix

Squamous cell carcinoma (SCC) of the uterine cervix occasionally demonstrates a deceptive growth pattern that mimics endocervical crypt involvement by cervical intraepithelial neoplasia, grade 3 (CIN 3). Such CIN 3-like SCCs may be misinterpreted as noninvasive or minimally invasive leading to delays in diagnosis. Little is known of the factors that influence the growth patterns of cervical SCC but we suggested recently that CIN 3-like tumors might demonstrate "collective cellular invasion," which is characterized by a retained epithelial phenotype. This contrasts with the more overtly infiltrative growth of conventional SCC, which exhibits features suggestive of epithelial-mesenchymal transition. In the current study we investigated podoplanin (PP) and SOX2 expression in normal squamous epithelium, in CIN 3 and in 16 CIN 3-like SCCs 11 of which also showed a conventional invasive component. Compared with normal epithelium, CIN 3 often showed a focal loss of basal PP staining and most cases showed increased, typically diffuse, SOX2 expression. Although the immunohistochemical findings were not uniform, they generally supported collective cellular invasion in CIN 3-like tumor areas as these were often PP positive and showed diffuse SOX2 expression. In contrast, most conventional SCCs showed only focal SOX2 staining and they were typically negative, or only focally positive, for PP. The staining patterns did not reliably distinguish CIN 3 from CIN 3-like SCC. Small infiltrative tumor nests around the margins of CIN 3 or deeply invasive CIN 3-like SCC often showed a localized reduction in SOX2 expression suggesting SOX2 downregulation during the transition to invasive growth.

BMX/Etk promotes cell proliferation and tumorigenicity of cervical cancer cells through PI3K/AKT/mTOR and STAT3 pathways

Bone marrow X-linked kinase (BMX, also known as Etk) has been reported to be involved in cell proliferation, differentiation, apoptosis, migration and invasion in several types of tumors, but its role in cervical carcinoma remains poorly understood. In this study, we showed that BMX expression exhibits a gradually increasing trend from normal cervical tissue to cervical cancer in situ and then to invasive cervical cancer tissue. Through BMX-IN-1, a potent and irreversible BMX kinase inhibitor, inhibited the expression of BMX, the cell proliferation was significantly decreased. Knockdown of BMX in HeLa and SiHa cervical cancer cell lines using two different silencing technologies, TALEN and shRNA, inhibited cell growth in vitro and suppressed xenograft tumor formation in vivo, whereas overexpression of BMX in the cell line C-33A significantly increased cell proliferation. Furthermore, a mechanism study showed that silencing BMX blocked cell cycle transit from G0/G1 to S or G2/M phase, and knockdown of BMX inhibited the expression of p-AKT and p-STAT3. These results suggested that BMX can promote cell proliferation through PI3K/AKT/mTOR and STAT3 signaling pathways in cervical cancer cells.

Cancer stem cells (CSCs), cervical CSCs and targeted therapies

Accumulating evidence has shown that cancer stem cells (CSCs) have a tumour-initiating capacity and play crucial roles in tumour metastasis, relapse and chemo/radio-resistance. As tumour propagation initiators, CSCs are considered to be promising targets for obtaining a better therapeutic outcome. Cervical carcinoma is the most common gynaecological malignancy and has a high cancer mortality rate among females. As a result, the investigation of cervical cancer stem cells (CCSCs) is of great value. However, the numbers of cancer cells and corresponding CSCs in malignancy are dynamically balanced, and CSCs may reside in the CSC niche, about which little is known to date. Therefore, due to their complicated molecular phenotypes and biological behaviours, it remains challenging to obtain “purified” CSCs and continuously culture CSCs for further in vitro studies without the cells losing their stem properties. At present, CSC-related markers and functional assays are used to purify, identify and therapeutically target CSCs both in vitro and in vivo. Nevertheless, CSC-related markers are not universal to all tumour types, although some markers may be valid in multiple tumour types. Additionally, functional identifications based on CSC-specific properties are usually limited in in vivo studies. Furthermore, an optimal method for identifying potential CCSCs in CCSC studies has not been previously published, and these techniques are currently of great importance. This article updates our knowledge on CSCs and CCSCs, reviews potential stem cell markers and functional assays for identifying CCSCs, and describes the potential of targeting CCSCs in the treatment of cervical carcinoma.

Inactivation of p38 MAPK contributes to stem cell-like properties of non-small cell lung cancer

Cancer stem cells (CSCs) are recognized as the major source for cancer initiation and recurrence. Yet, the mechanism by which the cancer stem cell properties are acquired and maintained in a cancer cell population is not well understood. In the current study, we observed that the level of active p38 MAPK is downregulated, while the level of the stemness marker SOX2 is upregulated in lung cancer tissues as compared to normal tissues. We further demonstrated that inactivation of p38 is a potential mechanism contributing to acquisition and maintenance of cancer stem cell properties in non-small cell lung cancer (NSCLC) cells. p38, in particular the p38γ and p38δ isoforms, suppresses the cancer stem cell properties and tumor initiating ability of NSCLC cells by promoting the ubiquitylation and degradation of stemness proteins such as SOX2, Oct4, Nanog, Klf4 and c-Myc, through MK2-mediated phosphorylation of Hsp27 that is an essential component of the proteasomal degradation machinery. In contrast, inactivation of p38 in lung cancer cells leads to upregulation of the stemness proteins, thus promoting the cancer stem cell properties of these cells. These findings have demonstrated a novel mechanism by which cancer stem cell properties are acquired and maintained in a cancer cell population, and have revealed a new function of the p38 pathway in suppressing cancer development. These studies have also identified a new pathway that can potentially serve as a target for cancer therapies aimed at eliminating CSCs.

Inhibition of RAD51 by siRNA and Resveratrol Sensitizes Cancer Stem Cells Derived from HeLa Cell Cultures to Apoptosis

Cervical cancer is the second most frequent tumor type in women worldwide with cases developing clinical recurrence, metastasis, and chemoresistance. The cancer stem cells (CSC) may be implicated in tumor resistance to therapy. RESveratrol (RES), a natural compound, is an antioxidant with multiple beneficial activities. We previously determined that the expression of RAD51 is decreased by RES. The aim of our study was to examine molecular mechanism by which CSC from HeLa cultures exhibit chemoresistance. We hypothesized CSC repair more efficiently DNA breaks and that RAD51 plays an important role in this mechanism. We found that CSC, derived from cervical cancer cell lines, overexpress RAD51 and are less sensitive to Etoposide (VP16). We inhibited RAD51 in CSC-enriched cultures using RES or siRNA against RAD51 messenger RNA and observed a decrease in cell viability and induction of apoptosis when treated simultaneously with VP16. In addition, we found that inhibition of RAD51 expression using RES also sensitizes CSC to VP16 treatment. Our results suggest that resveratrol is effective to sensitize cervical CSC because of RAD51 inhibition, targeting high RAD51 expressing CD49f-positive cells, which supports the possible therapeutic application of RES as a novel agent to treat cancer.

LGR5 promotes cancer stem cell traits and chemoresistance in cervical cancer

Cancer stem cells (CSCs), also known as tumor-initiating cells, contribute to tumorigenesis, resistance to chemoradiotherapy and recurrence in human cancers, suggesting targeting CSCs may represent a potential therapeutic strategy. Leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5) has recently been found to be a bona fide marker of colorectal CSCs. Our previous study showed that LGR5 functions as a tumor promoter in cervical cancer by activating the Wnt/β-catenin pathway. However, very little is known about the function or contribution of LGR5 to cervical CSCs. Here, we have modulated the expression of LGR5 using an overexpression vector or short hairpin RNA in cervical cancer cell lines. We demonstrated that elevated LGR5 expression in cervical cancer cells increased tumorsphere-forming efficiency; conferred chemoresistance to cisplatin treatment; augmented cell migration, invasion and clonogenicity; and elevated the levels of stem cell-related transcription factors in vitro. Furthermore, modulated LGR5⁺ cells, unlike LGR5^- cells, were highly tumorigenic in vivo. In addition, the modulated LGR5⁺ cells could give rise to both LGR5⁺ and LGR5^- cells in vitro and in vivo, thereby establishing a cellular hierarchy. Finally, we found that the increased tumorsphere-forming efficiency induced by LGR5 could be regulated through the inhibition or activation of the Wnt/β-catenin pathway in cervical cancer cells. Taken together, these results indicate that LGR5 has a vital oncogenic role by promoting cervical CSC traits and may represent a potential clinical target.

Increased SOX2 expression in salivary gland carcinoma ex pleomorphic adenoma progression: an association with adverse outcome

SOX2 is a regulatory factor of embryonic stem cells that has been implicated in carcinogenesis and cancer progression. We aimed to investigate the potential role of SOX2 in the stepwise progression from pleomorphic adenoma (PA) to invasive carcinoma ex pleomorphic adenoma (CXPA), evaluating its prognostic significance as well. Thirty PAs without malignant transformation and 25 CXPAs presenting both luminal or myoepithelial differentiation (7 intracapsular and 18 extracapsular) were evaluated immunohistochemically for SOX2 expression. Of these, 24 CXPAs (96%) were positive to SOX2, being 6 intracapsular carcinomas (85.7%) and all the 18 extracapsular carcinomas (100%). Residual PA areas and PA without malignant transformation were negative. High SOX2 expression levels (> 50% of positive cells) were correlated with high histological grade (p = 0.02), brisk mitotic activity (p = 0.01), advanced pT stage (p = 0.01), tumor recurrence (p = 0.01), and development of distant metastasis (p = 0.004). Still, overall survival rates were shorter in patients with extracapsular CXPA exhibiting diffuse SOX2 expression. These results suggest that SOX2 may play an important role in carcinogenesis and progression of CXPA and is also related with prognostic indicators in CXPAs with extracapsular invasion. Although direct therapeutic intervention in SOX2 may result in unwanted complications due to its constitutive functions, strategic approach to SOX2-related pathways may provide new therapeutic opportunities for patients with invasive CXPA.

SOX2 as a New Regulator of HPV16 Transcription

Persistent infections with high-risk human papillomavirus (HPV) constitute the main risk factor for cervical cancer development. HPV16 is the most frequent type associated to squamous cell carcinomas (SCC), followed by HPV18. The long control region (LCR) in the HPV genome contains the replication origin and sequences recognized by cellular transcription factors (TFs) controlling viral transcription. Altered expression of E6 and E7 viral oncogenes, modulated by the LCR, causes modifications in cellular pathways such as proliferation, leading to malignant transformation. The aim of this study was to identify specific TFs that could contribute to the modulation of high-risk HPV transcriptional activity, related to the cellular histological origin. We identified sex determining region Y (SRY)-box 2 (SOX2) response elements present in HPV16-LCR. SOX2 binding to the LCR was demonstrated by in vivo and in vitro assays. The overexpression of this TF repressed HPV16-LCR transcriptional activity, as shown through reporter plasmid assays and by the down-regulation of endogenous HPV oncogenes. Site-directed mutagenesis revealed that three putative SOX2 binding sites are involved in the repression of the LCR activity. We propose that SOX2 acts as a transcriptional repressor of HPV16-LCR, decreasing the expression of E6 and E7 oncogenes in a SCC context.

Targeted CDX2 expression inhibits aggressive phenotypes of colon cancer cells in vitro and in vivo

Loss of caudal type homeobox 2 (CDX2) is associated with the development of human colorectal cancer, while human telomerase reverse transcriptase (hTERT) frequently occurs in variety of human cancers. We investigated the effects of restoration of CDX2 expression using a hypoxia-inducible hTERT promoter-driven vector (pLVX-5HRE-hTERTp-CDX2-3FLAG) on colon cancer cell viability, cell cycle distribution, apoptosis, colony formation, invasion ability and xenograft tumor growth in nude mice. CDX2 overexpression significantly inhibited viability, colony formation, and the invasion and migration ability of LoVo cells, and induced cell cycle arrest and apoptosis in vitro, especially under hypoxic culture conditions. Overexpression of CDX2 under normoxic conditions significantly suppressed the expression of TGF-β, cyclin D1, uPA, MMP-9, MMP-2, and Bcl-2, and stimulated the expression of collagen IV, laminin-1, and Bax. Overexpression of CDX2 reduced colon cancer xenograft tumor formation in nude mice which was associated with downregulation of Ki-67. In conclusion, overexpression of CDX2 using a hypoxia-inducible hTERT promoter-driven vector suppressed malignant progression of colon cancer cells in vitro and in vivo. These results suggest that pLVX-5HRE-hTERTp-CDX2-3FLAG gene therapy may be a promising novel approach to treat colon cancer.

SOX2 Expression in Cervical Intraepithelial Neoplasia Grade 3 (CIN3) and Superficially Invasive (Stage IA1) Squamous Carcinoma of the Cervix

The transcription factor SOX2 plays an important role in tissue development and differentiation. In the neoplastic context, SOX2 has been shown to potentiate tumor invasion, and increased SOX2 immunoreactivity has been demonstrated in a variety of epithelial and nonepithelial malignancies often correlating with adverse prognosis. There are limited data on SOX2 expression in cervical squamous neoplasia and in particular, no studies have compared staining in cervical intraepithelial neoplasia (CIN)3 and in superficially invasive (Stage IA1) squamous cell carcinomas (SCC). We examined SOX2 expression in 12 cervical biopsies showing CIN3 only and 30 specimens with an initial diagnosis of Stage IA1 SCC; 7 of the latter samples did not demonstrate residual invasive foci in the study slides but all showed CIN3. There was variable staining in CIN3 without stromal invasion but CIN3 adjacent to SCC was more often SOX2 positive with 70% cases showing diffuse staining. CIN within endocervical crypts often showed more extensive SOX2 expression and in some cases staining was restricted to areas of crypt involvement. In contrast to CIN, most SCCs were SOX2 negative and there was often an abrupt loss of expression at the tumor-stromal interface. In summary, CIN3 usually showed increased SOX2 expression compared with normal epithelium, particularly in areas of endocervical crypt involvement and adjacent to superficially invasive SCC. However, most invasive tumor cells were unstained suggesting downregulation of SOX2 during the initial stages of the invasive process. Progression of cervical squamous neoplasia may involve cyclical alterations in SOX2 activity.