The SOX family of genes in cancer development: biological relevance and opportunities for therapy

Deciphering FOXM1 regulation: implications for stemness and metabolic adaptations in glioblastoma

The Forkhead box M1 (FOXM1) gene-mediated Wnt signaling pathway plays a significant role in the development and growth of glioblastoma multiforme (GBM), an exceptionally aggressive form of brain cancer. Our research explores the crucial involvement of the FOXM1 gene, a key transcription factor within the Wnt signaling pathway using bioinformatics techniques in both GBM and glioma stem cells (GSCs). Elevated FOXM1 gene expression is strongly associated with poor patient survival in GBM. Furthermore, FOXM1 gene expression is correlated with stemness-related factors, such as SOX2 and SOX9, which act as key drivers in the progression of cancer stem cells. Moreover, we specifically look into the direct associations of the FOXM1 gene with angiogenetic-related factors, metabolic genes, metastatic genes, pluripotency-related factors, immune cell infiltration, transcriptional networks, and functional category enrichment analysis, shedding light on the intricate molecular mechanisms involved in GBM initiation and progression. Additionally, our research identifies FOXM1-targeting miRNAs, revealing their potential as therapeutic candidates with implications for patient survival rates and DNA methylation patterns of the FOXM1 gene, uncovering insights into its epigenetic regulation. This knowledge contributes to a comprehensive understanding of the molecular landscape and potential avenues for developing more effective therapeutic approaches against GBM and GSCs.

FOXN3 Downregulation in Colorectal Cancer Enhances Tumor Cell Stemness by Promoting EP300-Mediated Epigenetic Upregulation of SOX12

Cancer stemness plays a crucial role in promoting the progression of colorectal cancer (CRC). Forkhead box N3 (FOXN3) is a tumor suppressor protein. Herein, we investigated the role of FOXN3 in the regulation of CRC cell stemness. Cell viability, proliferation, migration, and invasion were assessed utilizing cell counting kit-8 assay, 5-ethynyl-20-deoxyuridine assay, and Transwell assay, respectively. Cell-sphere formation was assessed using a sphere-forming assay. The enrichment of H3K27ac modifications at the SRY-related HMG-box 12 (SOX12) promoter, interactions among FOXN3, SOX12, and E1A binding protein p300 (EP300) were analyzed using chromatin immunoprecipitation or dual luciferase reporter assays. We found that FOXN3 overexpression inhibited CRC cell proliferation, migration, invasion, stemness, and tumor formation in mice by inactivating the Wnt/β-catenin signaling, while these effects of FOXN3 overexpression were reversed by the overexpression of SOX12. Mechanistically, EP300 increased SOX12 expression in CRC cells by promoting H3K27ac enrichment in the SOX12 promoter. In addition, FOXN3 transcriptionally inhibited EP300 expression in CRC cells by binding to the EP300 promoter. As expected, EP300 overexpression weakened the inhibitory effect of FOXN3 overexpression on CRC cell stemness. Collectively, FOXN3 upregulation inhibited CRC cell stemness by suppressing EP300-mediated epigenetic upregulation of SOX12.

Single-cell RNA-seq and pathological phenotype reveal the functional atlas and precise roles of Sox30 in testicular cell development and differentiation

Sox30 has recently been demonstrated to be a key regulator of spermatogenesis. However, the precise roles of Sox30 in the testis remain largely unclear. Here, the specific functions of Sox30 in testicular cells were determined by single-cell sequencing and confirmed via pathological analyses. Sox30 loss appears to damage all testicular cells to different extents. Sox30 chiefly drives the differentiation of primary spermatocytes. Sox30 deficiency causes spermatocyte arrest at the early phase of meiosis I, with nearly no normally developing second spermatocytes and three new spermatocyte -subclusters emerging. In addition, Sox30 seems to play important roles in the mature phenotypes of Sertoli and Leydig cells, and the proliferation and differentiation of spermatogonia. The developmental trajectory of germ cells begins with spermatogonia and splits into two different spermatocyte branches, with Sox30-null spermatocytes and wild-type spermatocytes placed at divergent ends. An opposite developmental trajectory of spermatocyte subclusters is observed, followed by incomplete development of spermatid subclusters in Sox30-null mice. Sox30 deficiency clearly alters the intercellular cross-talk of major testicular cells and dysregulates the transcription factor networks primarily involved in cell proliferation and differentiation. Mechanistically, Sox30 appears to have similar terminal functions that are involved mainly in spermatogenic development and differentiation among major testicular cells, and Sox30 performs these similar crucial roles through preferential regulation of different signalling pathways. Our study describes the exact functions of Sox30 in testicular cell development and differentiation and highlights the primary roles of Sox30 in the early meiotic phase of germ cells.

A cutting-edge investigation of the multifaceted role of SOX family genes in cancer pathogenesis through the modulation of various signaling pathways

This detailed study examines the complex role of the SOX family in various tumorigenic contexts, offering insights into how these transcription factors function in cancer. As the study progresses, it explores the specific contributions of each SOX family member. The significant roles of the SOX family in the oncogenic environment are well-recognized, highlighting a range of regulatory mechanisms that influence tumor progression. In brain, lung, and colorectal cancers, SOX types like SOX2, SOX3, and SOX4 promote the migration, proliferation, and angiogenesis of cancer cells. Conversely, in pancreatic, gastric, and breast cancers, SOX types, including SOX1, SOX9, and SOX17 inhibit various cancer cell activities such as proliferation and invasion. This thorough investigation enhances our understanding of the SOX family's complex role in cancer, establishing a foundation for future research and potential therapeutic strategies targeting these versatile transcription factors.

Intervention of epithelial mesenchymal transition against colon cancer cell growth and metastasis based on SOX21/POU4F2/Hedgehog signaling axis

AIMS

Colon cancer poses a major threat to human health and a heavy burden on the national economy. As a member of the SOX transcription factor family, SRY-box transcription factor 21 (SOX21) is associated with various cancers, but its mechanism of action in colon cancer remains unclear. This study focused on the molecular mechanisms of transcription factor SOX21 in proliferation and metastasis of colon cancer cells.

MAIN METHODS

We analyzed SOX21 expression level and its impact on survival in colon cancer patients by bioinformatics analysis. We used public databases for gene correlation, GSEA enrichment analysis. Cell function experiments (colony formation assay, wound healing assay, Transwell migration and invasion assay) were utilized to determine the impact of SOX21 silencing and over-expression on cell proliferation and metastasis. The luciferase reporter assay, CUT&RUN-qPCR assay and Methylation Specific PCR were used to explore SOX21-POU class 4 homeobox 2 (POU4F2) molecular interactions. The molecular mechanisms were verified by Quantitative real-time PCR and Western blot analysis.

KEY FINDINGS

SOX21 is highly expressed and affects the overall survival of colon cancer patients. SOX21 can attenuates POU4F2 methylation state by binding with it. In addition, this interaction facilitate its transcriptional activation of Hedgehog pathway, mediates epithelial-mesenchymal transition (EMT), consequently promoting the proliferation and metastasis of colon cancer cells.

SIGNIFICANCE

Our study reveals that SOX21 is an oncogenic molecule and suggests its regulatory role in colon carcinogenesis and progression, providing new insights into the treatment of this disease.

Implications of a De Novo Variant in the SOX12 Gene in a Patient with Generalized Epilepsy, Intellectual Disability, and Childhood Emotional Behavioral Disorders

SRY-box transcription factor (SOX) genes, a recently discovered gene family, play crucial roles in the regulation of neuronal stem cell proliferation and glial differentiation during nervous system development and neurogenesis. Whole exome sequencing (WES) in patients presenting with generalized epilepsy, intellectual disability, and childhood emotional behavioral disorder, uncovered a de novo variation within SOX12 gene. Notably, this gene has never been associated with neurodevelopmental disorders. No variants in known genes linked with the patient's symptoms have been detected by the WES Trio analysis. To date, any MIM phenotype number associated with intellectual developmental disorder has not been assigned for SOX12. In contrast, both SOX4 and SOX11 genes within the same C group (SoxC) of the Sox gene family have been associated with neurodevelopmental disorders. The variant identified in the patient here described was situated within the critical high-mobility group (HMG) functional site of the SOX12 protein. This domain, in the Sox protein family, is essential for DNA binding and bending, as well as being responsible for transcriptional activation or repression during the early stages of gene expression. Sequence alignment within SoxC (SOX12, SOX4 and SOX11) revealed a high conservation rate of the HMG region. The in silico predictive analysis described this novel variant as likely pathogenic. Furthermore, the mutated protein structure predictions unveiled notable changes with potential deleterious effects on the protein structure. The aim of this study is to establish a correlation between the SOX12 gene and the symptoms diagnosed in the patient.

Clinical Correlation of Transcription Factor SOX3 in Cancer: Unveiling Its Role in Tumorigenesis

Members of the SOX (SRY-related HMG box) family of transcription factors are crucial for embryonic development and cell fate determination. This review investigates the role of SOX3 in cancer, as aberrations in SOX3 expression have been implicated in several cancers, including osteosarcoma, breast, esophageal, endometrial, ovarian, gastric, hepatocellular carcinomas, glioblastoma, and leukemia. These dysregulations modulate key cancer outcomes such as apoptosis, epithelial-mesenchymal transition (EMT), invasion, migration, cell cycle, and proliferation, contributing to cancer development. SOX3 exhibits varied expression patterns correlated with clinicopathological parameters in diverse tumor types. This review aims to elucidate the nuanced role of SOX3 in tumorigenesis, correlating its expression with clinical and pathological characteristics in cancer patients and cellular modelsBy providing a comprehensive exploration of SOX3 involvement in cancer, this review underscores the multifaceted role of SOX3 across distinct tumor types. The complexity uncovered in SOX3 function emphasizes the need for further research to unravel its full potential in cancer therapeutics.

Biological functions and therapeutic potential of SRY related high mobility group box 5 in human cancer

Cancer is a heavy human burden worldwide, with high morbidity and mortality. Identification of novel cancer diagnostic and prognostic biomarkers is important for developing cancer treatment strategies and reducing mortality. Transcription factors, including SRY associated high mobility group box (SOX) proteins, are thought to be involved in the regulation of specific biological processes. There is growing evidence that SOX transcription factors play an important role in cancer progression, including tumorigenesis, changes in the tumor microenvironment, and metastasis. SOX5 is a member of SOX Group D of Sox family. SOX5 is expressed in various tissues of human body and participates in various physiological and pathological processes and various cellular processes. However, the abnormal expression of SOX5 is associated with cancer of various systems, and the abnormal expression of SOX5 acts as a tumor promoter to promote cancer cell viability, proliferation, invasion, migration and EMT through multiple mechanisms. In addition, the expression pattern of SOX5 is closely related to cancer type, stage and adverse clinical outcome. Therefore, SOX5 is considered as a potential biomarker for cancer diagnosis and prognosis. In this review, the expression of SOX5 in various human cancers, the mechanism of action and potential clinical significance of SOX5 in tumor, and the therapeutic significance of Sox5 targeting in cancer were reviewed. In order to provide a new theoretical basis for cancer clinical molecular diagnosis, molecular targeted therapy and scientific research.

The Role of SOX2 and SOX9 in Radioresistance and Tumor Recurrence

Head and neck squamous cell carcinoma (HNSCC) exhibits considerable variability in patient outcome. It has been reported that SOX2 plays a role in proliferation, tumor growth, drug resistance, and metastasis in a variety of cancer types. Additionally, SOX9 has been implicated in immune tolerance and treatment failures. SOX2 and SOX9 induce treatment failure by a molecular mechanism that has not yet been elucidated. This study explores the inverse association of SOX2/SOX9 and their distinct expression in tumors, influencing the tumor microenvironment and radiotherapy responses. Through public RNA sequencing data, human biopsy samples, and knockdown cellular models, we explored the effects of inverted SOX2 and SOX9 expression. We found that patients expressing SOX2LowSOX9High showed decreased survival compared to SOX2HighSOX9Low. A survival analysis of patients stratified by radiotherapy and human papillomavirus brings additional clinical relevance. We identified a gene set signature comprising newly discovered candidate genes resulting from inverted SOX2/SOX9 expression. Moreover, the TGF-β pathway emerges as a significant predicted contributor to the overexpression of these candidate genes. In vitro findings reveal that silencing SOX2 enhances tumor radioresistance, while SOX9 silencing enhances radiosensitivity. These discoveries lay the groundwork for further studies on the therapeutic potential of transcription factors in optimizing HNSCC treatment.

Clinical implications and genetical insights of SOX6 expression in acute myeloid leukemia

BACKGROUND

Transcription factor SOX6 belongs to Sry-related high-mobility-group box (SOX) family, has been reported to be downregulated and acts as a tumor-suppressor gene in various solid tumors, but in acute myeloid leukemia (AML) is incompletely understood.

METHODS

The SOX6 expression was analyzed between AML patients and normal controls from public data and our research cohort. Correlations between SOX6 expression and clinical, genetic features together with survival were further analyzed.

RESULTS

In both public and our present datasets, we demonstrated that SOX6 expression is notably downregulated in AML patients compared with normal controls. Moreover, the expression level of SOX6 was dynamic, along with the disease status. SOX6 was significantly decreased in relapsed/refractory AML compared with complete remission AML. Clinically, SOX6 underexpression was significantly correlated with bone marrow blasts, and WBC counts. Furthermore, decreased expression of SOX6 was more common in core binding factor AML (CBF-AML), rarely found in complex karyotype AML (CK-AML), and correlated with FLT3 mutations. By survival analyses, low-expression of SOX6 was associated with shorter overall survival (OS) and event-free survival (EFS) among cytogenetic normal AML (CN-AML) patients. Moreover, both univariate and multivariate analyses showed that low SOX6 expression was an independent unfavorable prognostic biomarker for CN-AML.

CONCLUSIONS

Our findings indicated that SOX6 underexpression, as a frequent event in AML, was associated with genetic abnormalities and prognosis in AML. SOX6 might be a valuable biomarker for risk stratification, predicting prognosis and relapse of AML.

Inside the stemness engine: Mechanistic links between deregulated transcription factors and stemness in cancer

Cell identity is largely determined by its transcriptional profile. In tumour, deregulation of transcription factor expression and/or activity enables cancer cell to acquire a stem-like state characterised by capacity to self-renew, differentiate and form tumours in vivo. These stem-like cancer cells are highly metastatic and therapy resistant, thus warranting a more complete understanding of the molecular mechanisms downstream of the transcription factors that mediate the establishment of stemness state. Here, we review recent research findings that provide a mechanistic link between the commonly deregulated transcription factors and stemness in cancer. In particular, we describe the role of master transcription factors (SOX, OCT4, NANOG, KLF, BRACHYURY, SALL, HOX, FOX and RUNX), signalling-regulated transcription factors (SMAD, β-catenin, YAP, TAZ, AP-1, NOTCH, STAT, GLI, ETS and NF-κB) and unclassified transcription factors (c-MYC, HIF, EMT transcription factors and P53) across diverse tumour types, thereby yielding a comprehensive overview identifying shared downstream targets, highlighting unique mechanisms and discussing complexities.

Impact of SOX2 function and regulation on therapy resistance in bladder cancer

Bladder cancer (BC) is a malignant disease with high rates of recurrence and mortality. It is mainly classified as non-muscle-invasive BC and muscle-invasive BC (MIBC). Often, MIBC is chemoresistant, which, according to cancer stem cells (CSCs) theory, is linked to the presence of bladder cancer stem cells (BCSCs). Sex-determining region Y- (SRY) Box transcription factor 2 (SOX2), which is a molecular marker of BCSCs, is aberrantly over-expressed in chemoresistant BC cell lines. It is one of the standalone prognostic factors for BC, and it has an inherently significant function in the emergence and progression of the disease. This review first summarizes the role of SRY-related high-mobility group protein Box (SOX) family genes in BC, focusing on the SOX2 and its significance in BC. Second, it discusses the mechanisms relevant to the regulation of SOX2. Finally, it summarizes the signaling pathways related to SOX2 in BC, suggests current issues to be addressed, and proposes potential directions for future research to provide new insights for the treatment of BC.

Transcriptomic analysis of mRNA expression in giant congenital melanocytic nevi

BACKGROUND AND OBJECTIVE

GCMN is a sporadic disease with an incidence ranging from 1/20,000 to 1/500000. So far, several studies have found that GCMN is related to somatic mutations, but most of them have focused on known pathogenic genes, and transcriptome sequencing based on large datasets is relatively uncommon. At present, the use of next-generation sequencing technologies and bioinformatics platforms makes genomic information study more comprehensive and efficient. In this study, the transcriptome differences between GCMN lesions and surrounding normal skin tissues were investigated using high-throughput transcriptome sequencing, and hub genes and pathways related to pathogenesis were identified, providing a theoretical foundation for further research into the pathogenesis of GCMN.

METHODS

Pathological skin tissue and surrounding normal skin tissue from GCMN patients, namely the pathological group (PG) and the control group (CG), were obtained. 1. All specimens were stained with HE to ensure that the samples met the experimental requirements. 2. Ten pairs of specimens were selected for high-throughput transcriptome sequencing, and the differentially expressed genes (DEGs) between the PG and the CG were obtained. The DEGs were analyzed by clusterProfiler R software for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The function of the subnetwork was analyzed and the hub genes were identified by the STRING database and Cytoscape software. 3. The expression differences of hub genes PTGS2, EGF, and SOX10 in pathological skin tissues and normal skin tissues were verified by qRT-PCR and immunofluorescence staining.

RESULTS

1. HE staining revealed a lot of melanocytes in the dermis and subcutaneous tissues. They were found around the hair follicles, sweat glands, sebaceous glands, and blood vessel walls, or in a specific pattern. 2. The screening threshold was set at p<0.01 and |log2fc|<1, and a total of 1163 DEGs were discovered between the PG and CG, with 519 genes up-regulated and 644 genes down-regulated in the pathological tissues. According to the GO functional analysis, 29 biological processes, 18 cell compositions, and 17 molecular functions were significantly enriched, with the majority of them being related to keratinocytes and the extracellular matrix. There were 779 nodes and 2359 interactions in the protein interaction network. Using the MCODE plug-in, the network was divided into 25 functional clusters. According to ClueGO results, Cluster5 was involved in melanin biosynthesis and melanocyte proliferation. Using 11 operation methods in the Cytohubba plug-in, PTGS2, EGF, and SOX10 in Cluster5 were chosen as hub genes. 3. qRT-PCR and immunofluorescent staining revealed that compared to normal skin tissue, the expression of SOX10 was significantly up-regulated, and the expression of PTGS2 and EGF was significantly down-regulated in pathological skin tissue(P<0.001).

CONCLUSIONS

In GCMN, keratinocytes and extracellular matrix may directly and indirectly affect melanocyte activity. PTGS2, EGF, and SOX10 are important genes and significantly differentially expressed in pathological and normal skin tissues. These findings may serve as a springboard for future research.

Downstream Regulatory Network of MYBL2 Mediating Its Oncogenic Role in Melanoma

The transcription factor MYBL2 is widely expressed in proliferating cells. Aberrant expression of MYBL2 contributes to tumor malignancy and is associated with poor patient prognosis. However, the downstream transcriptional network that mediates its oncogenic properties remains elusive. In the present study, we observed that MYBL2 was overexpressed in malignant and metastatic melanoma patient samples and that the high expression level of MYBL2 was significantly associated with poor prognosis. A loss-of-function study demonstrated that MYBL2 depletion significantly decreased cell proliferation and migration and prevented cell cycle progression. We also determined that MYBL2 promoted the formation of melanoma stem-like cell populations, indicating its potential as a therapeutic target for treating resistant melanoma. Mechanistically, we constructed an MYBL2 regulatory network in melanoma by integrating RNA-seq and ChIP-seq data. EPPK1, PDE3A, and FCGR2A were identified as three core target genes of MYBL2. Importantly, multivariate Cox regression and survival curve analysis revealed that PDE3A and EPPK1 were negatively correlated with melanoma patient survival; however, FCGR2A was positively correlated with patient survival. Overall, our findings elucidate an MYBL2 regulatory network related to cell proliferation and cancer development in melanoma, suggesting that MYBL2 may be potentially targeted for melanoma diagnosis and treatment.

Glioma Stem Cells Upregulate CD39 Expression to Escape Immune Response through SOX2 Modulation

Simple Summary

Glioblastoma is the most malignant tumor of the central nervous system. Glioma stem cells are the cause of adverse outcomes such as early recurrence and low overall survival in glioma patients. Targeting glioma stem cells is considered a promising anti-glioma strategy, Although CD39 plays a key role in the initiation and regulation of DC-mediated antigen-specific immune responses, its impact on GSCs is unclear. Therefore, we systematically investigated the effect of CD39 on extracellular ATP levels, dendritic cell recruitment and T cell killing in glioma stem cells. The molecular mechanism by which SOX2 binds to the CD39 promoter to regulate extracellular ATP levels, and evaluated the immune response enhanced by inhibition of CD39 after ADM treatment in a mouse glioma model. We suggest that CD39 is an effective target for glioma immunotherapy.

Abstract

Ectonucleotidase CD39 hydrolyzing extracellular ATP (eATP) functions as a key modulator of immune response in the tumor microenvironment, yet the role of CD39 in contributing tumor stem cells in a more immunosuppressive microenvironment remains elusive. Here we report that the upregulation of CD39 is crucial for the decrease of extracellular ATP concentration around glioma stem cells (GSCs) to maintain an immunosuppressive microenvironment. Adriamycin (ADM) is able to promote the release of ATP, which recruits dendritic cells (DCs) to phagocytose GSCs. CD39 inhibition further increased extracellular ATP concentrations following ADM treatment and DCs phagocytosis. In addition, GSCs upregulated CD39 expression by SOX2-binding CD39 promotor. In mouse tumor models, the combination of ADM and CD39 blockade increased immune cell infiltration and reduced tumor size. These findings suggest that GSCs upregulate CD39 expression by their biological characteristics to maintain an immunosuppressive microenvironment, and CD39 inhibition supplies a favorable tumor microenvironment (TME) for immunotherapeutic intervention and enhances the immune response induced by chemotherapy.

Understanding the function and regulation of Sox2 for its therapeutic potential in breast cancer

Sox family of transcriptional factors play essential functions in development and are implicated in multiple clinical disorders, including cancer. Sox2 being their most prominent member and performing a critical role in reprogramming differentiated adult cells to an embryonic phenotype is frequently upregulated in multiple cancers. High Sox2 levels are detected in breast tumor tissues and correlate with a worse prognosis. In addition, Sox2 expression is connected with resistance to conventional anticancer therapy. Together, it can be said that inhibiting Sox2 expression can reduce the malignant features associated with breast cancer, including invasion, migration, proliferation, stemness, and chemoresistance. This review highlights the critical roles played by the Sox gene family members in initiating or suppressing breast tumor development, while primarily focusing on Sox2 and its role in breast tumor initiation, maintenance, and progression, elucidates the probable mechanisms that control its activity, and puts forward potential therapeutic strategies to inhibit its expression.

UCH-L3 structure and function: Insights about a promising drug target

In the past few years, researchers have shed light on the immense importance of ubiquitin in numerous regulatory pathways. The post-translational addition of mono or poly-ubiquitin molecules namely "ubiquitinoylation" is therefore pivotal to maintain the cell's vitality, maturation, differentiation, and division. Part of conserving homeostasis stems from maintaining the ubiquitin pool in the vicinity of the cell's intracellular environment; this crucial role is played by deubiquitylating enzymes (DUBs) that cleave ubiquitin molecules from target molecules. To date, they are categorized into 7 families with ubiquitin carboxyl c-terminal de-hydrolase family (UCH) as the most common and well-studied. Ubiquitin C-terminal hydrolase L (UCH-L3) is a significant protein in this family as it has been implicated in many molecular and cellular processes with its mRNA identified in a range of body tissues including the brain. It goes without saying that it manifests in maintaining health and when abnormally regulated in disease. As it is an attractive small molecule drug target, scientists have used high throughput screening (HTS) and other drug discovery methods to discover inhibitors for this enzyme for the treatment of cancer and neurodegenerative diseases. In this review we present an overview of UCH-L3 catalytic mechanism, structure, its role in DNA repair and cancer along with the inhibitors discovered so far to halt its activity.

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.

SOX transcription factors and glioma stem cells: Choosing between stemness and differentiation

Glioblastoma (GBM) is the most common, most aggressive and deadliest brain tumor. Recently, remarkable progress has been made towards understanding the cellular and molecular biology of gliomas. GBM tumor initiation, progression and relapse as well as resistance to treatments are associated with glioma stem cells (GSCs). GSCs exhibit a high proliferation rate and self-renewal capacity and the ability to differentiate into diverse cell types, generating a range of distinct cell types within the tumor, leading to cellular heterogeneity. GBM tumors may contain different subsets of GSCs, and some of them may adopt a quiescent state that protects them against chemotherapy and radiotherapy. GSCs enriched in recurrent gliomas acquire more aggressive and therapy-resistant properties, making them more malignant, able to rapidly spread. The impact of SOX transcription factors (TFs) on brain tumors has been extensively studied in the last decade. Almost all SOX genes are expressed in GBM, and their expression levels are associated with patient prognosis and survival. Numerous SOX TFs are involved in the maintenance of the stemness of GSCs or play a role in the initiation of GSC differentiation. The fine-tuning of SOX gene expression levels controls the balance between cell stemness and differentiation. Therefore, innovative therapies targeting SOX TFs are emerging as promising tools for combatting GBM. Combatting GBM has been a demanding and challenging goal for decades. The current therapeutic strategies have not yet provided a cure for GBM and have only resulted in a slight improvement in patient survival. Novel approaches will require the fine adjustment of multimodal therapeutic strategies that simultaneously target numerous hallmarks of cancer cells to win the battle against GBM.

MicroRNAs regulating SOX2 in cancer progression and therapy response

The proliferation, metastasis and therapy response of tumour cells are tightly regulated by interaction among various signalling networks. The microRNAs (miRNAs) can bind to 3'-UTR of mRNA and down-regulate expression of target gene. The miRNAs target various molecular pathways in regulating biological events such as apoptosis, differentiation, angiogenesis and migration. The aberrant expression of miRNAs occurs in cancers and they have both tumour-suppressor and tumour-promoting functions. On the contrary, SOX proteins are capable of binding to DNA and regulating gene expression. SOX2 is a well-known member of SOX family that its overexpression in different cancers to ensure progression and stemness. The present review focuses on modulatory impact of miRNAs on SOX2 in affecting growth, migration and therapy response of cancers. The lncRNAs and circRNAs can function as upstream mediators of miRNA/SOX2 axis in cancers. In addition, NF-κB, TNF-α and SOX17 are among other molecular pathways regulating miRNA/SOX2 axis in cancer. Noteworthy, anti-cancer compounds including bufalin and ovatodiolide are suggested to regulate miRNA/SOX2 axis in cancers. The translation of current findings to clinical course can pave the way to effective treatment of cancer patients and improve their prognosis.

Oncogenic Potential of the Dual-Function Protein MEX3A

MEX3A belongs to the MEX3 (Muscle EXcess) protein family consisting of four members (MEX3A-D) in humans. Characteristic for MEX3 proteins is their domain structure with 2 HNRNPK homology (KH) domains mediating RNA binding and a C-terminal really interesting new gene (RING) domain that harbors E3 ligase function. In agreement with their domain composition, MEX3 proteins were reported to modulate both RNA fate and protein ubiquitination. MEX3 paralogs exhibit an oncofetal expression pattern, they are severely downregulated postnatally, and re-expression is observed in various malignancies. Enforced expression of MEX3 proteins in various cancers correlates with poor prognosis, emphasizing their oncogenic potential. The latter is supported by MEX3A's impact on proliferation, self-renewal as well as migration of tumor cells in vitro and tumor growth in xenograft studies.

The genetic variability, phylogeny and functional significance of E6, E7 and LCR in human papillomavirus type 52 isolates in Sichuan, China

Background

Variations in human papillomavirus (HPV) E6 and E7 have been shown to be closely related to the persistence of the virus and the occurrence and development of cervical cancer. Long control region (LCR) of HPV has been shown multiple functions on regulating viral transcription. In recent years, there have been reports on E6/E7/LCR of HPV-16 and HPV-58, but there are few studies on HPV-52, especially for LCR. In this study, we focused on gene polymorphism of the HPV-52 E6/E7/LCR sequences, assessed the effects of variations on the immune recognition of viral E6 and E7 antigens, predicted the effect of LCR variations on transcription factor binding sites and provided more basic date for further study of E6/E7/LCR in Chengdu, China.

Methods

LCR/E6/E7 of the HPV-52 were amplified and sequenced to do polymorphic and phylogenetic analysis. Sequences were aligned with the reference sequence by MEGA 7.0 to identify SNP. A neighbor-joining phylogenetic tree was constructed by MEGA 7.0, followed by the secondary structure prediction of the related proteins using PSIPRED 4.0. The selection pressure of E6 and E7 coding regions were estimated by Bayes empirical Bayes analysis of PAML 4.9. The HLA class-I and II binding peptides were predicted by the Immune Epitope Database server. The B cell epitopes were predicted by ABCpred server. Transcription factor binding sites in LCR were predicted by JASPAR database.

Results

50 SNP sites (6 in E6, 10 in E7, 34 in LCR) were found. From the most variable to the least variable, the nucleotide variations were LCR > E7 > E6. Two deletions were found between the nucleotide sites 7387–7391 (TTATG) and 7698–7700 (CTT) in all samples. A deletion was found between the nucleotide sites 7287–7288 (TG) in 97.56% (40/41) of the samples. The combinations of all the SNP sites and deletions resulted in 12 unique sequences. As shown in the neighbor-joining phylogenetic tree, except for one belonging to sub-lineage C2, others sequences clustered into sub-lineage B2. No positive selection was observed in E6 and E7. 8 non-synonymous amino acid substitutions (including E3Q and K93R in the E6, and T37I, S52D, Y59D, H61Y, D64N and L99R in the E7) were potential affecting multiple putative epitopes for both CD4+ and CD8+ T-cells and B-cells. A7168G was the most variable site (100%) and the binding sites for transcription factor VAX1 in LCR. In addition, the prediction results showed that LCR had the high probability binding sites for transcription factors SOX9, FOS, RAX, HOXA5, VAX1 and SRY.

Conclusion

This study provides basic data for understanding the relation among E6/E7/LCR mutations, lineages and carcinogenesis. Furthermore, it provides an insight into the intrinsic geographical relatedness and biological differences of the HPV-52 variants, and contributes to further research on the HPV-52 therapeutic vaccine development.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-021-01565-5.

Sex-Determining Region Y Chromosome-Related High-Mobility-Group Box 10 in Cancer: A Potential Therapeutic Target

Sex-determining region Y-related high mobility group-box 10 (SOX10), a member of the SOX family, has recently been highlighted as an essential transcriptional factor involved in developmental biology. Recently, the functionality of SOX 10 has been increasingly revealed by researchers worldwide. It has been reported that SOX10 significantly regulates the proliferation, migration, and apoptosis of tumors and is closely associated with the progression of cancer. In this review, we first introduce the basic background of the SOX family and SOX10 and then discuss the pathophysiological roles of SOX10 in cancer. Besides, we enumerate the application of SOX10 in the pathological diagnosis and therapeutic potential of cancer. Eventually, we summarize the potential directions and perspectives of SOX10 in neoplastic theranostics. The information compiled herein may assist in additional studies and increase the potential of SOX10 as a therapeutic target for cancer.

Role of SOX Protein Groups F and H in Lung Cancer Progression

Simple Summary

The expression of SOX proteins has been demonstrated in many tissues at various stages of embryogenesis, where they play the role of transcription factors. The SOX18 protein (along with SOX7 and SOX17) belongs to the SOXF group and is mainly involved in the development of the cardiovascular system, where its expression was found in the endothelium. SOX18 expression was also demonstrated in neoplastic lines of gastric, pancreatic and colon adenocarcinomas. The prognostic role of SOX30 expression has only been studied in lung adenocarcinomas, where a low expression of this factor in the stromal tumor was associated with a worse prognosis for patients. Because of the complexity of non-small-cell lung cancer (NSCLC) development, the role of the SOX proteins in this malignancy is still not fully understood. Many recently published papers show that SOX family protein members play a crucial role in the progression of NSCLC.

Abstract

The SOX family proteins are proved to play a crucial role in the development of the lymphatic ducts and the cardiovascular system. Moreover, an increased expression level of the SOX18 protein has been found in many malignances, such as melanoma, stomach, pancreatic breast and lung cancers. Another SOX family protein, the SOX30 transcription factor, is responsible for the development of male germ cells. Additionally, recent studies have shown its proapoptotic character in non-small cell lung cancer cells. Our preliminary studies showed a disparity in the amount of mRNA of the SOX18 gene relative to the amount of protein. This is why our attention has been focused on microRNA (miRNA) molecules, which could regulate the SOX18 gene transcript level. Recent data point to the fact that, in practically all types of cancer, hundreds of genes exhibit an abnormal methylation, covering around 5–10% of the thousands of CpG islands present in the promoter sequences, which in normal cells should not be methylated from the moment the embryo finishes its development. It has been demonstrated that in non-small-cell lung cancer (NSCLC) cases there is a large heterogeneity of the methylation process. The role of the SOX18 and SOX30 expression in non-small-cell lung cancers (NSCLCs) is not yet fully understood. However, if we take into account previous reports, these proteins may be important factors in the development and progression of these malignancies.

Low SOX12 Expression Is Correlated With Poor Prognosis in Patients With Gastric Cancer

Background:

SRY-related HMG box-12, which is associated with the prognosis of cancer, has been frequently described. However, both SRY-related HMG box-12 expression and its relationship with clinicopathological variables and patient survival have not been defined in gastric cancer. The aim of our study was to examine the prognostic value of SRY-related HMG box-12 expression in patients with gastric cancer.

Methods:

In this study, we determined SRY-related HMG box-12 expression in 79 primary gastric cancer tissues and 79 matched adjacent nontumor tissues by immunohistochemistry and then calculated the survival rate using the Kaplan-Meier method. Cox proportional hazard regression model was used to analyze predictors of gastric cancer. Western blot and quantitative real-time polymerase chain reaction were used to investigate the difference in SRY-related HMG box-12 expression between normal gastric epithelial cells and gastric cancer cells at the protein level and RNA level, respectively.

Results:

SRY-related HMG box-12 was downregulated in gastric cancer tissues. Low SRY-related HMG box-12 expression was significantly associated not only with lymph node metastasis (P = .027) and TNM stage (P = .021) but also with disease-specific survival in patients with gastric cancer. Multivariate analysis demonstrated TNM stage was an independent factor predicting poor survival (P = .034).

Conclusions:

Low SRY-related HMG box-12 expression is associated with poor clinical outcomes in gastric cancer.

MRP3-Mediated Chemoresistance in Cholangiocarcinoma: Target for Chemosensitization Through Restoring SOX17 Expression

BACKGROUND AND AIMS

A limitation for the treatment of unresectable cholangiocarcinoma (CCA) is its poor response to chemotherapy, which is partly due to reduction of intracellular levels of anticancer drugs through ATP-binding cassette (ABC) pumps. Low expression of SOX17 (SRY-box containing gene 17), a transcription factor that promotes biliary differentiation and phenotype maintenance, has been associated with cholangiocyte malignant transformation. Whether SOX17 is also involved in CCA chemoresistance is investigated in this study.

APPROACH AND RESULTS

SOX17 expression in human CCA cells (EGI-1 and TFK-1) selectively potentiated cytotoxicity of SN-38, 5-fluorouracil and mitoxantrone, but not that of gemcitabine, capecitabine, cisplatin, or oxaliplatin. The analysis of the resistome by TaqMan low-density arrays revealed changes affecting primarily ABC pump expression. Single-gene quantitative real-time PCR, immunoblot, and immunofluorescence analyses confirmed that MRP3 (multidrug resistance associated protein 3), which was highly expressed in CCA human tumors, was down-regulated in SOX17-transduced CCA cells. The substrate specificity of this pump matched that of SOX17-induced in vitro selective chemosensitization. Functional studies showed lower ability of SOX17-expressing CCA cells to extrude specific MRP3 substrates. Reporter assay of MRP3 promoter (ABCC3pr) revealed that ABCC3pr activity was inhibited by SOX17 expression and SOX2/SOX9 silencing. The latter was highly expressed in CCA. Moreover, SOX2/9, but not SOX17, induced altered electrophoretic mobility of ABCC3pr, which was prevented by SOX17. The growth of CCA tumors subcutaneously implanted into immunodeficient mice was inhibited by 5-fluorouracil. This effect was enhanced by co-treatment with adenoviral vectors encoding SOX17.

CONCLUSIONS

SOX9/2/17 are involved in MRP3-mediated CCA chemoresistance. Restored SOX17 expression, in addition to its tumor suppression effect, induces selective chemosensitization due to MRP3 down-regulation and subsequent intracellular drug accumulation.

SOX18 exerts tumor-suppressive functions in papillary thyroid carcinoma through inhibition of Wnt/β-catenin signaling

Sex-determining region on the Y chromosome-related high mobility group box 18 (SOX18) has emerged as a key tumor-related protein in a wide range of human tumors. Yet, the involvement of SOX18 in papillary thyroid carcinoma has not been determined. This study aimed to explore the expression and biological function of SOX18 in papillary thyroid carcinoma. There was a significant decrease in SOX18 expression in papillary thyroid carcinoma tissues compared with that in normal tissues. Low expression of SOX18 was also detected in papillary thyroid carcinoma cell lines and upregulation of SOX18 effectively repressed the proliferative, colony-forming and invasive abilities of papillary thyroid carcinoma cells in vitro. In contrast, knockdown of SOX18 in papillary thyroid carcinoma cells was associated with a significant increase in cell proliferation and invasion. Further studies revealed that SOX18 upregulation was associated with the reduced nuclear accumulation of β-catenin and the downregulation of Wnt/β-catenin signaling in thyroid carcinoma cells. Moreover, inhibition of Wnt/β-catenin signaling markedly attenuated SOX18 knockdown-evoked oncogenic effects in papillary thyroid carcinoma cells. In addition, SOX18 overexpression remarkably retarded the tumor growth of papillary thyroid carcinoma cell-derived xenograft tumors in nude mice. Taken together, these results demonstrate that SOX18 suppresses the proliferation and invasion of papillary thyroid carcinoma by inhibiting Wnt/β-catenin signaling. Our study reveals a tumor-suppressive role of SOX18 in papillary thyroid carcinoma and suggests that SOX18 is an attractive candidate target for treatment of papillary thyroid carcinoma.

SOX30 confers a tumor suppressive effect in acute myeloid leukemia through inactivation of Wnt/β-catenin signaling

Recent studies suggested SRY-related high mobility group box 30 (SOX30) as a candidate tumor-promoter or tumor-inhibitor in multiple tumor types. Yet, the detailed role of SOX30 in acute myeloid leukemia (AML) has not been well studied. The present research was designed to investigate the detailed relevance of SOX30 in AML. The data of our study indicated that SOX30 expression was markedly downregulated in AML cells, a pattern associated with its hypermethylation. SOX30 overexpression caused a marked reduction in AML cell proliferation and colony formation, but it promoted AML cell apoptosis. By contrast, SOX30 depletion by small interfering RNA (siRNA)-mediated gene silencing had the opposite effect. Moreover, SOX30 overexpression markedly decreased β-catenin expression, a change that led to inactivation of Wnt/β-catenin pathway. Notably, restoration of β-catenin expression partially reversed SOX30-mediated tumor suppressive effect in AML cells. In an AML-derived mouse xenograft model, SOX30 overexpression remarkably retarded the tumor growth in vivo. Overall, these data of the study suggest a tumor-inhibition role of SOX30 in AML, and highlight a key role of SOX30/Wnt/β-catenin axis in the progression of AML.

A New Approach for Cancer Immunotherapy Based on the Cancer Stem Cell Antigens Properties

BACKGROUND

Cancer stem cells (CSCs) are a rare population of tumor cells, which play an important role in tumor initiation, progression, and maintenance. The concept that cancer cells arise from stem cells was presented about 150 years ago. Recently, this hypothesis was renewed considering the heterogeneity of tumor cells. CSCs are resistant to chemo- and radio-therapy. Therefore, targeting CSCs could be a novel and effective strategy to struggle with tumor cells.

OBJECTIVE

In this mini-review, we highlight that different immunotherapeutic approaches can be used to target cancer cells and eradicate different tumor cells. The most important targets are specific markers recognized on the CSC surface as CSC antigens such as CD44, CD133, Aldehyde Dehydrogenase (ALDH), and SOX family members. This article emphasizes recent advances in CSCs in cancer therapy.

RESULTS

Our results present that CSC antigens play an important role in tumor initiation, especially in the cells that are resistant to chemo- and radiotherapy agents. Therefore, they are ideal targets for cancer immunotherapy, for instance, in developing different types of cancer vaccines or antibodies against tumor cells.

CONCLUSION

The current studies related to cancer immunotherapy through targeting the CSC antigens based on their properties are briefly summarized. Altogether, CSC antigens can be efficiently targeted to treat cancer patients.

Downregulation of microR-147b represses the proliferation and invasion of thyroid carcinoma cells by inhibiting Wnt/β-catenin signaling via targeting SOX15

microRNA-147b (miR-147b) is a newly identified tumor-related miRNA that is dysregulated in multiple cancer types. Yet, the role of miR-147b in thyroid carcinoma remains unknown. Herein, we found that miR-147b expression was upregulated in thyroid carcinoma tissues and cell lines. miR-147b inhibition decreased the proliferation, colony formation, and invasion of thyroid carcinoma cells. The tumor suppressive gene SRY-related high-mobility-group box gene 15 (SOX15) was predicted as a miR-147b target gene. SOX15 expression was markedly decreased in thyroid carcinoma tissues and inversely correlated with the miR-147b expression. SOX15 overexpression repressed the proliferation and invasion of thyroid carcinoma cells associated with downregulation of Wnt/β-catenin signaling. SOX15 knockdown abolished the miR-147b-inhibition-mediated antitumor effect. miR-147b inhibition or SOX15 overexpression retarded the tumor growth of thyroid carcinoma cells in vivo. Overall, our study suggests that miR-147b inhibition restrains the proliferation and invasion of thyroid carcinoma cells through upregulation of SOX15 and inhibition of Wnt/β-catenin signaling.

HDAC5-mediated deacetylation and nuclear localisation of SOX9 is critical for tamoxifen resistance in breast cancer

BACKGROUND

Tamoxifen resistance remains a significant clinical challenge for the therapy of ER-positive breast cancer. It has been reported that the upregulation of transcription factor SOX9 in ER⁺ recurrent cancer is sufficient for tamoxifen resistance. However, the mechanisms underlying the regulation of SOX9 remain largely unknown.

METHODS

The acetylation level of SOX9 was detected by immunoprecipitation and western blotting. The expressions of HDACs and SIRTs were evaluated by qRT-PCR. Cell growth was measured by performing MTT assay. ALDH-positive breast cancer stem cells were evaluated by flow cytometry. Interaction between HDAC5 and SOX9 was determined by immunoprecipitation assay.

RESULTS

Deacetylation is required for SOX9 nuclear translocation in tamoxifen-resistant breast cancer cells. Furthermore, HDAC5 is the key deacetylase responsible for SOX9 deacetylation and subsequent nuclear translocation. In addition, the transcription factor C-MYC directly promotes the expression of HDAC5 in tamoxifen resistant breast cancer cells. For clinical relevance, high SOX9 and HDAC5 expression are associated with lower survival rates in breast cancer patients treated with tamoxifen.

CONCLUSIONS

This study reveals that HDAC5 regulated by C-MYC is essential for SOX9 deacetylation and nuclear localisation, which is critical for tamoxifen resistance. These results indicate a potential therapy strategy for ER⁺ breast cancer by targeting C-MYC/HDAC5/SOX9 axis.

Molecular mechanistic insights: The emerging role of SOXF transcription factors in tumorigenesis and development

Over the last decade, the development and progress of next-generation sequencers incorporated with classical biochemical analyses have drastically produced novel insights into transcription factors, including Sry-like high-mobility group box (SOX) factors. In addition to their primary functions in binding to and activating specific downstream genes, transcription factors also participate in the dedifferentiation or direct reprogramming of somatic cells to undifferentiated cells or specific lineage cells. Since the discovery of SOX factors, members of the SOXF (SOX7, SOX17, and SOX18) family have been identified to play broad roles, especially with regard to cardiovascular development. More recently, SOXF factors have been recognized as crucial players in determining the cell fate and in the regulation of cancer cells. Here, we provide an overview of research on the mechanism by which SOXF factors regulate development and cancer, and discuss their potential as new targets for cancer drugs while offering insight into novel mechanistic transcriptional regulation during cell lineage commitment.

SOX2 in development and cancer biology

The transcription factor SOX2 is essential for embryonic development and plays a crucial role in maintaining the stemness of embryonic cells and various adult stem cell populations. On the other hand, dysregulation of SOX2 expression is associated with a multitude of cancer types and it has been shown that SOX2 positively affects cancer cell traits such as the capacity to proliferate, migrate, invade and metastasize. Moreover, there is growing evidence that SOX2 mediates resistance towards established cancer therapies and that it is expressed in cancer stem cells. These findings indicate that studying the role of SOX2 in the context of cancer progression could lead to the development of new therapeutic options. In this review, the current knowledge about the role of SOX2 in development, maintenance of stemness, cancer progression and the resistance towards cancer therapies is summarized.

Transcription factors in SOX family: Potent regulators for cancer initiation and development in the human body

Transcription factors (TFs) have a key role in controlling the gene regulatory network that sustains explicit cell states in humans. However, an uncontrolled regulation of these genes potentially results in a wide range of diseases, including cancer. Genes of the SOX family are indeed crucial as deregulation of SOX family TFs can potentially lead to changes in cell fate as well as irregular cell growth. SOX TFs are a conserved group of transcriptional regulators that mediate DNA binding through a highly conserved high-mobility group (HMG) domain. Accumulating evidence demonstrates that cell fate and differentiation in major developmental processes are controlled by SOX TFs. Besides; numerous reports indicate that both up- and down-regulation of SOX TFs may induce cancer progression. In this review, we discuss the involvement of key TFs of SOX family in human cancers.

dTcf/Pangolin suppresses growth and tumor formation in Drosophila

Wnt/Wingless (Wg) signaling controls many aspects of animal development and is deregulated in different human cancers. The transcription factor dTcf/Pangolin (Pan) is the final effector of the Wg pathway in Drosophila and has a dual role in regulating the expression of Wg target genes. In the presence of Wg, dTcf/Pan interacts with β-catenin/Armadillo (Arm) and induces the transcription of Wg targets. In absence of Wg, dTcf/Pan partners with the transcriptional corepressor TLE/Groucho (Gro) and inhibits gene expression. Here, we use the wing imaginal disk of Drosophila as a model to examine the functions that dTcf/Pan plays in a proliferating epithelium. We report a function of dTcf/Pan in growth control and tumorigenesis. Our results show that dTcf/Pan can limit tissue growth in normal development and suppresses tumorigenesis in the context of oncogene up-regulation. We identify the conserved transcription factors Sox box protein 15 (Sox15) and Ftz transcription factor 1 (Ftz-f1) as genes controlled by dTcf/Pan involved in tumor development. In conclusion, this study reports a role for dTcf/Pan as a repressor of normal and oncogenic growth and identifies the genes inducing tumorigenesis downstream of dTcf/Pan.

The role of SOX family members in solid tumours and metastasis

Cancer is a heavy burden for humans across the world with high morbidity and mortality. Transcription factors including sex determining region Y (SRY)-related high-mobility group (HMG) box (SOX) proteins are thought to be involved in the regulation of specific biological processes. The deregulation of gene expression programs can lead to cancer development. Here, we review the role of the SOX family in breast cancer, prostate cancer, renal cell carcinoma, thyroid cancer, brain tumours, gastrointestinal and lung tumours as well as the entailing therapeutic implications. The SOX family consists of more than 20 members that mediate DNA binding by the HMG domain and have regulatory functions in development, cell-fate decision, and differentiation. SOX2, SOX4, SOX5, SOX8, SOX9, and SOX18 are up-regulated in different cancer types and have been found to be associated with poor prognosis, while the up-regulation of SOX11 and SOX30 appears to be favourable for the outcome in other cancer types. SOX2, SOX4, SOX5 and other SOX members are involved in tumorigenesis, e.g. SOX2 is markedly up-regulated in chemotherapy resistant cells. The SoxF family (SOX7, SOX17, SOX18) plays an important role in angio- and lymphangiogenesis, with SOX18 seemingly being an attractive target for anti-angiogenic therapy and the treatment of metastatic disease in cancer. In summary, SOX transcription factors play an important role in cancer progression, including tumorigenesis, changes in the tumour microenvironment, and metastasis. Certain SOX proteins are potential molecular markers for cancer prognosis and putative potential therapeutic targets, but further investigations are required to understand their physiological functions.

Targeting SOX2 in anticancer therapy

INTRODUCTION

SOX2 is a transcription factor that is important in the development and maintenance of the stem cell state. Furthermore, SOX2 is associated with cancer progression because it promotes the migration, invasion, and proliferation of cancer cells. SOX2 is also expressed in cancer stem cells and appears to be involved in the resistance toward anticancer therapies. These features render SOX2 an attractive target for cancer therapy. Areas covered: In this review, we highlight the role of SOX2 in cancer and in the resistance toward anticancer therapies. We summarize recent studies dealing with SOX2 as a direct or indirect therapeutic target in cancer. Expert opinion: SOX2 is an attractive target in cancer therapy because of its role in cancer progression and therapy resistance. SOX2 is a transcription factor, hence direct targeting is difficult. Studies aimed at a functional depletion, for example by knock-down with siRNAs, are difficult to translate into clinical settings. Alternatively, the identification of SOX2 upstream or downstream regulators that are easier to target is of paramount importance.

Role of the SOX18 protein in neoplastic processes

There is a high demand for anticancer drugs due to the fact that the chemotherapeutics currently used have numerous side effects, which lowers the patient's quality of life. However, the latest antibody therapies are extremely expensive, hence the requirement to identify novel, equally effective but low-toxic treatments that have limited side effects. As a result of this, a number of research centres around the world are attempting to identify novel molecular markers that could be effective targets for anticancer therapy in the future. The SOX18 protein has been suggested to be a significant diagnostic and prognostic marker in various types of cancer. SRY-related HMG-box 18 (SOX18) is an important transcription factor involved in the development of cardiovascular and lymphatic vessels during embryonic development. In addition, it is involved in the progression of atherosclerosis and wound-healing processes. It has been observed that its level is higher in a number of cancer types, including melanoma, pancreas, stomach, liver, breast, lung, ovarian and cervical cancer. Furthermore, an association between a high expression of SOX18 in gastric cancer stromal cells and a poor prognosis has been demonstrated. The literature indicates how complex the pathogenesis of cancer is. Knowing the molecular basis of the pathogenesis of the tumor will allow for the effective use of targeted therapy, which may result in a higher success in treating patients. It is therefore important to identify novel and effective therapies as well as new proteins that could be potential markers. The SOX18 family, represented by the SOX18 protein, seems to be in this respect a promising element in modern anticancer therapy.

SOX30 Inhibits Tumor Metastasis through Attenuating Wnt-Signaling via Transcriptional and Posttranslational Regulation of β-Catenin in Lung Cancer

Although high mortality of lung cancer is greatly due to distant metastasis, the mechanism of this metastasis remains unclear. Here, we investigate in lung cancer that SOX30 is sharply under-expressed in metastatic tumors compared with non-metastatic tumors, and suppresses plenty of metastasis related processes or pathways. SOX30 strongly inhibits tumor cell metastasis in vitro and in vivo. Sox30 deficiency promotes lung metastasis in Sox30^−/− mice and this uncontrollable lung-metastasis is re-inhibited upon Sox30 re-expression. Mechanistically, SOX30 diminishes Wnt-signaling via directly transcriptional repressing β-catenin or interacting with β-catenin to compete with TCF for binding to β-catenin. The carboxyl-terminus of SOX30 is required for attenuating β-catenin transcriptional activity, whereas the amino-terminus of SOX30 is required for its interaction with β-catenin protein. Enhance of β-catenin attenuates the anti-metastatic role of SOX30. Moreover, Sox30 deficiency promotes tumor metastasis and reduces survival of mice. In addition, nuclear SOX30 expression is closely associated with metastasis and represents a favorable independent prognostic biomarker of lung cancer patients. Altogether, these results highlight an important role and mechanism of SOX30 in lung cancer metastasis, providing a potential therapeutic target for anti-metastasis.

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SOX30 is closely associated with lung cancer metastasis, and strongly inhibits cancer cell metastasis in vitro and in vivo.

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SOX30 suppresses cancer metastasis via transcriptional repressing β-catenin or competing with TCF for β-catenin binding.

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SOX30 deficiency promotes tumor long-distance metastasis and reduces overall survival of mice and lung cancer patients.

The high mortality of lung cancer is largely due to distant-metastases. However, the mechanism of this metastasis remains unclear. Here, we demonstrate that SOX30 strongly inhibits lung cancer metastasis in vitro and in vivo. As an important metastatic suppressor, SOX30 prevents long-distant metastases and causes fine prognosis inhibiting Wnt-signaling via transcriptional repressing β-catenin or competing with TCF for interaction with β-catenin. This study provides useful information for effective therapies against tumor-metastasis. Considering key role of β-catenin in tumor-metastasis and ineffective treatment using inhibitors against β-catenin, it is a potential choice to suppress Wnt/β-catenin activity via targeting the upstream SOX30.

SOX2 and SOX12 are predictive of prognosis in patients with clear cell renal cell carcinoma

Sex-determining region Y-box protein (SOX) genes serve an important role in cancer growth and metastasis. The present study aimed to determine the predictive ability of SOX and associated genes identified through molecular network in clear cell renal cell carcinoma (RCC). A total of 505 patients with clear cell RCC from The Cancer Genome Atlas (TCGA) cohorts were collected in this study. The expression profile of SOX and associated genes were obtained from the TCGA RNAseq database. Clinicopathological characteristics, including age, gender, tumor grade, stage, laterality disease-free-survival and overall survival (OS) were collected. Cox's proportional hazards regression model, as well as Kaplan-Meier curves were used to assess the relative factors. Selected genes of SOXs that demonstrated significant associations with OS were further validated in 192 patients from the validation cohort. In the univariate Cox regression model, SOX1, SOX2, SOX6, SOX11, SOX12, SOX13, SOX15, SOX17 and SOX30 expression were predictive in the prognosis of clear cell RCC. Following adjustment for clinical factors, SOX2 [hazard ratio (HR), 1.130; 95% confidence interval (CI), 1.002-1.275), SOX12 (HR, 1.379; 95% CI, 1.060-1.793) and SOX15 (HR, 1.245; 95% CI, 1.063-1.459) remained statistically significant. Furthermore, POU class 5 homeobox 1 (POU5F1), POU2F1 and nuclear receptor subfamily 5 group A member 1 in the gene cluster network analysis associated with SOX2 did not reduce the statistical significance when added to the multivariate analysis. The findings were extended to the Fudan University Shanghai Cancer Center cohort. The results revealed that high SOX2 and SOX12 expression were associated with poor prognosis for OS (log-rank test, all P<0.05). SOX2 and SOX12 were identified as independent prognostic factors of OS in clear cell RCC.

Overexpression of SOX11 and TFE3 in Solid-Pseudopapillary Neoplasms of the Pancreas

OBJECTIVES

To characterize the expression of SOX11 and TFE3 proteins in solid-pseudopapillary neoplasms (SPNs) and their histologic mimickers.

METHODS

Immunohistochemistry for SOX11, TFE3, and β-catenin was performed on 31 cases of surgically resected SPNs. Neuroendocrine tumors, acinar cell carcinomas, and pancreatoblastomas served as controls.

RESULTS

Nuclear immunoreactivity for SOX11 was detected in all SPNs and five of 31 control tumors. Nuclear immunoreactivity for TFE3 was detected in 30 SPNs and three control tumors. Nuclear immunoreactivity for β-catenin was detected in all SPNs and four control tumors. The combination of three markers as immunohistochemical panels resulted in optimal sensitivity and specificity.

CONCLUSIONS

Both SOX11 and TFE3 were overexpressed in SPNs and may be involved in the pathogenesis. Clinically, SOX11 and TFE3 can be potentially used as diagnostic markers in distinguishing indeterminate SPNs from their histologic mimickers.

Promoter hypermethylation of SOX11 correlates with adverse clinicopathological features of human prostate cancer

Currently available tools for early diagnosis and prognosis of prostate cancer lack sufficient accuracy. There is a need to identify novel biomarkers for this common malignancy. SOX family genes play an important role in embryogenesis and are also implicated in various cancers. SOX11 has been recently recognized as a potential tumour suppressor that is downregulated in prostate cancer. We hypothesized that hypermethylation may be responsible for SOX11 silencing in human prostate cancer. The aim of the study was to investigate SOX11 promoter methylation in prostate adenocarcinoma by comparing it with benign prostatic hyperplasia (BPH). A total of 143 human prostate tissue samples, 62 from patients with prostate cancer and 81 from patients with BPH were examined by methylation-specific PCR. Associations between SOX11 promoter methylation and clinicopathological parameters were assessed by univariate statistics. Detection rates of SOX11 promoter methylation were 80.6% and 35.8% in prostate cancer and BPH respectively (P < 0.001). SOX11 hypermethylation was associated with adverse clinicopathological characteristics of prostate cancer, including higher PSA level (P < 0.01), Gleason score ≥ 7 (P = 0.03) and perineural invasion (P = 0.03). SOX11 methylation was positively correlated with the PSA level (P = 0.001). Our data indicated that SOX11 can be a promising methylation marker candidate for differential diagnosis and risk stratification for prostate cancer.

SOX8 regulates cancer stem-like properties and cisplatin-induced EMT in tongue squamous cell carcinoma by acting on the Wnt/β-catenin pathway

A sub-population of chemoresistant cells exhibits biological properties similar to cancer stem cells (CSCs), and these cells are believed to be a main cause for tumor relapse and metastasis. In our study, we explored the role of SOX8 and its molecular mechanism in the regulation of the stemness properties and the epithelial mesenchymal transition (EMT) of cisplatin-resistant tongue squamous cell carcinoma (TSCC) cells. We found that SOX8 was upregulated in cisplatin-resistant TSCC cells, which displayed CSC-like properties and exhibited EMT. SOX8 was also overexpressed in chemoresistant patients with TSCC and was associated with higher lymph node metastasis, advanced tumor stage and shorter overall survival. Stable knockdown of SOX8 in cisplatin-resistant TSCC cells inhibited chemoresistance, tumorsphere formation, and EMT. The Wnt/β-catenin pathway mediated the cancer stem-like properties in cisplatin-resistant TSCC cells. Further studies showed that the transfection of active β-catenin in SOX8 stable-knockdown cells partly rescued the SOX8 silencing-induced repression of stem-like features and chemoresistance. Through chromatin immunoprecipitation and luciferase assays, we observed that SOX8 bound to the promoter region of Frizzled-7 (FZD7) and induced the FZD7-mediated activation of the Wnt/β-catenin pathway. In summary, SOX8 confers chemoresistance and stemness properties and mediates EMT processes in chemoresistant TSCC via the FZD7-mediated Wnt/β-catenin pathway.

Adaptive NetworkProfiler for Identifying Cancer Characteristic-Specific Gene Regulatory Networks

There is currently much discussion about sample (patient)-specific gene regulatory network identification, since the efficiently constructed sample-specific gene networks lead to effective personalized cancer therapy. Although statistical approaches have been proposed for inferring gene regulatory networks, the methods cannot reveal sample-specific characteristics because the existing methods, such as an L₁-type regularization, provide averaged results for all samples. Thus, we cannot reveal sample-specific characteristics in transcriptional regulatory networks. To settle on this issue, the NetworkProfiler was proposed based on the kernel-based L₁-type regularization. The NetworkProfiler imposes a weight on each sample based on the Gaussian kernal function for controlling effect of samples on modeling a target sample, where the amount of weight depends on similarity of cancer characteristics between samples. The method, however, cannot perform gene regulatory network identification well for a target sample in a sparse region (i.e., for a target sample, there are only a few samples having a similar characteristic of the target sample, where the characteristic is considered as a modulator in sample-specific gene network construction), since a constant bandwidth in the Gaussian kernel function cannot effectively group samples for modeling a target sample in sparse region. The cancer characteristics, such as an anti-cancer drug sensitivity, are usually nonuniformly distributed, and thus modeling for samples in a sparse region is also a crucial issue. We propose a novel kernel-based L₁-type regularization method based on a modified k-nearest neighbor (KNN)-Gaussian kernel function, called an adaptive NetworkProfiler. By using the modified KNN-Gaussian kernel function, our method provides robust results against the distribution of modulators, and properly groups samples according to a cancer characteristic for sample-specific analysis. Furthermore, we propose a sample-specific generalized cross-validation for choosing the sample-specific tuning parameters in the kernel-based L₁-type regularization method. Numerical studies demonstrate that the proposed adaptive NetworkProfiler effectively performs sample-specific gene network construction. We apply the proposed statistical strategy to the publicly available Sanger Genomic data analysis, and extract anti-cancer drug sensitivity-specific gene regulatory networks.

SOX15 regulates proliferation and migration of endometrial cancer cells

The study aimed to investigate the effects of Sry-like high mobility group box 15 (SOX15) on proliferation and migration of endometrial cancer (EC) cells. Immunohistochemistry (IHC) was applied to determine the expression of SOX15 in EC tissues and adjacent tissues. We used cell transfection method to construct the HEC-1-A and Ishikawa cell lines with stable overexpression and low expression SOX15. Reverse-transcription quantitative real-time PCR (RT-qPCR) and Western blot were performed to examine expression of SOX15 mRNA and SOX15 protein, respectively. By conducting a series of cell proliferation assay and migration assay, we analyzed the influence of SOX15 overexpression or low expression on EC cell proliferation and migration. The expression of SOX15 mRNA and protein in EC tissues was significantly lower than that in adjacent tissues. After lentivirus-transfecting SOX15, the expression level of SOX15 mRNA and protein was significantly increased in cells of SOX15 group, and decreased in sh-SOX15 group. Overexpression of SOX15 could suppress cell proliferation, while down-regulation of SOX15 increased cell proliferation. Flow cytometry results indicated that overexpression of SOX15 induced the ratio of cell-cycle arrest in G₁ stage. In addition, Transwell migration assay results showed that SOX15 overexpression significantly inhibited cell migration, and also down-regulation of SOX15 promoted the migration. As a whole, SOX15 could regulate the proliferation and migration of EC cells and up- regulation of SOX15 could be valuable for EC treatment.

Extract of Spatholobus suberctus Dunn ameliorates ischemia-induced injury by targeting miR-494

Cerebral stroke is a leading cause of death and permanent disability. The current therapeutic outcome of ischemic stroke (>85% of all strokes) is very poor, thus novel therapeutic drug is urgently needed. In vitro cell model of ischemia was established by oxygen-glucose deprivation (OGD) and in vivo animal model of ischemia was established by middle cerebral artery occlusion (MCAO). The effects of Spatholobus suberctus Dunn extract (SSCE) on OGD-induced cell injury, MCAO-induced neural injury and miR-494 level were all evaluated. The possible target genes were virtually screened utilizing bioinformatics and verified by luciferase assay. Subsequently, the effects of abnormally expressed miR-494 on OGD-induced cell injury and target gene expression were determined. Additionally, whether SSCE affected target gene expression through modulation of miR-494 was studied. Finally, the effects of aberrantly expressed Sox8 on OGD-induced injury and signaling pathways were estimated. SSCE reduced OGD-induced cell injury and ameliorated MCAO-induced neuronal injury, along with down-regulation of miR-494. Then, OGD-induced cell injury was increased by miR-494 overexpression but decreased by miR-494 silence. Sox8 was a target gene of miR-494, and SSCE could up-regulate Sox8 expression via down-regulating miR-494. Afterwards, OGD-induced cell injury was proved to be increased by Sox8 inhibition but reduced by Sox8 overexpression. Finally, OGD-induced inhibition of PI3K/AKT/mTOR and MAPK pathways was further inhibited by Sox8 silence but activated by Sox8 overexpression. SSCE ameliorates ischemia-induced injury both in vitro and in vivo by miR-494-mediated modulation of Sox8, involving activations of PI3K/AKT/mTOR and MAPK pathways.

SOX17 regulates cholangiocyte differentiation and acts as a tumor suppressor in cholangiocarcinoma

BACKGROUND & AIMS

Cholangiocarcinoma (CCA) is a biliary malignancy linked to genetic and epigenetic abnormalities, such as hypermethylation of SOX17 promoter. Here, the role of SOX17 in cholangiocyte differentiation and cholangiocarcinogenesis was studied.

METHODS

SOX17 expression/function was evaluated along the differentiation of human induced pluripotent stem cells (iPSC) into cholangiocytes, in the dedifferentiation process of normal human cholangiocytes (NHC) in culture and in cholangiocarcinogenesis. Lentiviruses for SOX17 overexpression or knockdown were used. Gene expression and DNA methylation profiling were performed.

RESULTS

SOX17 expression is induced in the last stage of cholangiocyte differentiation from iPSC and regulates the acquisition of biliary markers. SOX17 becomes downregulated in NHC undergoing dedifferentiation; experimental SOX17 knockdown in differentiated NHC downregulated biliary markers and promoted baseline and Wnt-dependent proliferation. SOX17 expression is lower in human CCA than in healthy tissue, which correlates with worse survival after tumor resection. In CCA cells, SOX17 overexpression decreased their tumorigenic capacity in murine xenograft models, which was related to increased oxidative stress and apoptosis. In contrast, SOX17 overexpression in NHC did not affect their survival but inhibited their baseline proliferation. In CCA cells, SOX17 inhibited migration, anchorage-independent growth and Wnt/β-catenin-dependent proliferation, and restored the expression of biliary markers and primary cilium length. In human CCA, SOX17 promoter was found hypermethylated and its expression inversely correlates with the methylation grade. In NHC, Wnt3a decreased SOX17 expression in a DNMT-dependent manner, whereas in CCA, DNMT1 inhibition or silencing upregulated SOX17.

CONCLUSIONS

SOX17 regulates the differentiation and maintenance of the biliary phenotype and functions as a tumor suppressor for CCA, being a potential prognostic marker and a promising therapeutic target.

LAY SUMMARY

Understanding the molecular mechanisms involved in the pathogenesis of CCA is key in finding new valuable diagnostic and prognostic biomarkers, as well as therapeutic targets. This study provides evidence that SOX17 regulates the differentiation and maintenance of the biliary phenotype, and its downregulation promotes their tumorigenic transformation. SOX17 acts as a tumor suppressor in CCA and its genetic, molecular and/or pharmacological restoration may represent a new promising therapeutic strategy. Moreover, SOX17 expression correlates with the outcome of patients after tumor resection, being a potential prognostic biomarker.