Targeting SOX2 in anticancer therapy

Dihydrotanshinone I enhanced BRAF mutant melanoma treatment efficacy by inhibiting the STAT3/SOX2 signaling pathway

BACKGROUND

The Food and Drug Administration has approved the Serine/threonine-protein kinase B-raf (BRAF) inhibitor and Mitogen-activated extracellular signal-regulated kinase (MEK) inhibitor combo as the first-line treatment for individuals with metastatic melanoma, although the majority of these patients exhibit primary or secondary drug resistance in the clinic. Dihydrotanshinone I (DHT) is a lipophilic compound extracted from the root of Salvia miltiorrhiza that has been linked to multiple antitumor activities. In this study, we investigated the effect of dihydrotanshinone I on the MAPK pathway inhibitor resistance of BRAF mutant malignant melanoma.

METHOD

After treating A375, A375R, and A2058 cells with DHT or a combination of DHT and BRAF/MEK inhibitors, WB and Real-Time RT-qPCR were used to confirm the activation of the MAPK and STAT3/SOX2 pathways. CCK-8 was used to assess cell viability, while flow cytometry was used to identify apoptosis. In addition, mice were inoculated with A375 cells to establish a model of tumour formation, and various drug groups and treatment models were utilized. The diameter and weight of tumours in each group were then measured, and IHC and HE staining were used to assess the expression of two pathways and cytotoxicity, respectively.

RESULTS

This study found that DHT directly interacts with STAT3 protein and it can stop the feedback activation of the STAT3/SOX2 pathway caused by the use of MAPK pathway inhibitors. In addition, the combination of DHT and BRAF/MEK inhibitors can inhibit the proliferation and growth of BRAF mutant melanoma cells and primary and secondary drug-resistant cells. Finally, we proved that the combined therapy of DHT and BRAF/MEK inhibitors is reliable and effective at animal and cell levels.

CONCLUSION

In BRAF mutant melanoma cells, DHT suppresses the STAT3/SOX2 signaling pathway. Combining DHT, BRAF inhibitors, and MEK inhibitors can help treat treatment-resistant BRAF mutant melanoma cells. Experimental results both in vitro and in vivo have shown that the combination of DHT and an inhibitor of the MAPK pathway is safer and more successful than using an inhibitor of the MAPK pathway alone when treating BRAF mutant melanoma.

IMPA1-derived inositol maintains stemness in castration-resistant prostate cancer via IMPDH2 activation

Acquisition of prostate cancer stem cells (PCSCs) manifested during androgen ablation therapy (ABT) contributes to castration-resistant prostate cancer (CRPC). However, little is known about the specific metabolites critically orchestrating this process. Here, we show that IMPA1-derived inositol enriched in PCSCs is a key metabolite crucially maintaining PCSCs for CRPC progression and ABT resistance. Notably, conditional Impa1 knockout in the prostate abrogates the pool and properties of PCSCs to orchestrate CRPC progression and prolong the survival of TRAMP mice. IMPA1-derived inositol serves as a cofactor that directly binds to and activates IMPDH2, which synthesizes guanylate nucleotides for maintaining PCSCs with ARlow/- features leading to CRPC progression and ABT resistance. IMPA1/inositol/IMPDH2 axis is upregulated in human prostate cancer, and its overexpression predicts poor survival outcomes. Genetically and pharmacologically targeting the IMPA1/inositol/IMPDH2 axis abrogates CRPC and overcomes ABT resistance in various CRPC xenografts, patient-derived xenograft (PDX) tumor models, and TRAMP mouse models. Our study identifies IMPDH2 as an inositol sensor whose activation by inositol represents a key mechanism for maintaining PCSCs for CRPC and ABT resistance.

Dissecting SOX2 expression and function reveals an association with multiple signaling pathways during embryonic development and in cancer progression

SRY (Sex Determining Region) box 2 (SOX2) is an essential transcription factor that plays crucial roles in activating genes involved in pre- and post-embryonic development, adult tissue homeostasis, and lineage specifications. SOX2 maintains the self-renewal property of stem cells and is involved in the generation of induced pluripotency stem cells. SOX2 protein contains a particular high-mobility group domain that enables SOX2 to achieve the capacity to participate in a broad variety of functions. The information about the involvement of SOX2 with gene regulatory elements, signaling networks, and microRNA is gradually emerging, and the higher expression of SOX2 is functionally relevant to various cancer types. SOX2 facilitates the oncogenic phenotype via cellular proliferation and enhancement of invasive tumor properties. Evidence are accumulating in favor of three dimensional (higher order) folding of chromatin and epigenetic control of the SOX2 gene by chromatin modifications, which implies that the expression level of SOX2 can be modulated by epigenetic regulatory mechanisms, specifically, via DNA methylation and histone H3 modification. In view of this, and to focus further insights into the roles SOX2 plays in physiological functions, involvement of SOX2 during development, precisely, the advances of our knowledge in pre- and post-embryonic development, and interactions of SOX2 in this scenario with various signaling pathways in tumor development and cancer progression, its potential as a therapeutic target against many cancers are summarized and discussed in this article.

Blood-, Tissue- and Urine-Based Prognostic Biomarkers of Upper Tract Urothelial Carcinoma

Upper tract urothelial carcinoma (UTUC) is a rare but aggressive neoplasm. Currently, there are few reliable and widely used prognostic biomarkers of this disease. The purpose of this study was to assess the prognostic value of blood-, tissue- and urine-based biomarkers in patients with UTUC. A comprehensive literature search was conducted using the PubMed, Cochrane and Embase databases. Case reports, editorials and non-peer-reviewed literature were excluded from the analysis. As a result, 94 articles were included in this review. We evaluated the impact of 22 blood-based, 13 tissue-based and 4 urine-based biomarkers and their influence on survival outcomes. The neutrophil-lymphocyte ratio, albumin, C-reactive protein, De Ritis ratio, renal function and fibrinogen, which are currently mentioned in the European Association of Urology (EAU) guidelines, are well researched and most probably allow for a reliable prognosis estimate. However, our review highlights a number of other promising biomarkers that could potentially predict oncological outcomes in patients with UTUC. Nonetheless, the clinical value of some prognostic factors remains uncertain due to the lack of comprehensive studies.

Dexamethasone-tamoxifen combination exerts synergistic therapeutic effects in tamoxifen-resistance breast cancer cells

Tamoxifen (TAM) is a key player in estrogen receptor-positive (ER+) breast cancer (BC); however, ∼30% of patients experience relapse and a lower survival rate due to TAM resistance. TAM resistance was related to the over expression of SOX-2 gene, which is regulated by the E2F3 transcription factor in the Wnt signaling pathway. It was suggested that SOX-2 overexpression was suppressed by dexamethasone (DEX), a glucocorticoid commonly prescribed to BC patients. The aim of the present study is to explore the effect of combining DEX and TAM on the inhibition of TAM-resistant LCC-2 cells (TAMR-1) through modulating the E2F3/SOX-2-mediated Wnt signaling pathway. The effect of the combination therapy on MCF-7 and TAMR-1 cell viability was assessed. Drug interactions were analyzed using CompuSyn and SynergyFinder softwares. Cell cycle distribution, apoptotic protein expression, gene expression levels of SOX-2 and E2F3, and cell migration were also assessed. Combining DEX with TAM led to synergistic inhibition of TAMR-1 cell proliferation and migration, induced apoptosis, reduced SOX-2 and E2F3 expression and was also associated with S and G2-M phase arrest. Therefore, combining DEX with TAM may present an effective therapeutic option to overcome TAM resistance, by targeting the E2F3/SOX-2/Wnt signaling pathway, in addition to its anti-inflammatory effect.

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

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

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

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

Morphological and Molecular Biological Characteristics of Experimental Rat Glioblastoma Tissue Strains Induced by Different Carcinogenic Chemicals

Glioblastoma (GBM) is a highly aggressive human neoplasm with poor prognosis due to its malignancy and therapy resistance. To evaluate the efficacy of antitumor therapy, cell models are used most widely, but they are not as relevant to human GBMs as tissue models of gliomas, closely corresponding to human GBMs in cell heterogeneity. In this work, we compared three different tissue strains of rat GBM 101.8 (induced by DMBA), GBM 11-9-2, and GBM 14-4-5 (induced by ENU).

MATERIALS AND METHODS

We estimated different gene expressions by qPCR-RT and conducted Western blotting and histological and morphometric analysis of three different tissue strains of rat GBM.

RESULTS

GBM 101.8 was characterized by the shortest period of tumor growth and the greatest number of necroses and mitoses; overexpression of Abcb1, Sox2, Cdkn2a, Cyclin D, and Trp53; and downregulated expression of Vegfa, Pdgfra, and Pten; as well as a high level of HIF-1α protein content. GBM 11-9-2 and GBM 14-4-5 were relevant to low-grade gliomas and characterized by downregulated Mgmt expression; furthermore, a low content of CD133 protein was found in GBM 11-9-2.

CONCLUSIONS

GBM 101.8 is a reliable model for further investigation due to its similarity to high-grade human GBMs, while GBM 11-9-2 and GBM 14-4-5 correspond to Grade 2-3 gliomas.

SOX2 and OCT4 mediate radiation and drug resistance in pancreatic tumor organoids

Pancreatic cancer has a five-year survival rate of only 10%, mostly due to late diagnosis and limited treatment options. In patients with unresectable disease, either FOLFIRINOX, a combination of 5-fluorouracil (5-FU), oxaliplatin and irinotecan, or gemcitabine plus nab-paclitaxel combined with radiation are frontline standard regimens. However, chemo-radiation therapy has shown limited success because patients develop resistance to chemotherapy and/or radiation. In this study, we evaluated the role of pancreatic cancer stem cells (CSC) using OCT4 and SOX2, CSC markers in mouse pancreatic tumor organoids. We treated pancreatic tumor organoids with 4 or 8 Gy of radiation, 10 μM of 5-FU (5-Fluorouracil), and 100 μM 3-Bromopyruvate (3BP), a promising anti-cancer drug, as a single treatment modalities, and in combination with RT. Our results showed significant upregulation of, OCT4, and SOX2 expression in pancreatic tumor organoids treated with 4 and 8 Gy of radiation, and downregulation following 5-FU treatment. The expression of CSC markers with increasing treatment dose exhibited elevated upregulation levels to radiation and downregulation to 5-FU chemotherapy drug. Conversely, when tumor organoids were treated with a combination of 5-FU and radiation, there was a significant inhibition in SOX2 and OCT4 expression, indicating CSC self-renewal inhibition. Noticeably, we also observed that human pancreatic tumor tissues exhibited heterogeneous and aberrant OCT4 and SOX2 expression as compared to normal pancreas, indicating their potential role in pancreatic cancer growth and therapy resistance. In addition, the combination of 5-FU and radiation treatment exhibited significant inhibition of the β-catenin pathway in pancreatic tumor organoids, resulting in sensitization to treatment and organoid death. In conclusion, our study emphasizes the crucial role of CSCs in therapeutic resistance in PC treatment. We recommend using tumor organoids as a model system to explore the impact of CSCs in PC and identify new therapeutic targets.

Significance of OCT3/4 and SOX2 antigens expression by leukemic blast cells in adult acute leukemia

OBJECTIVE

This study aimed to address the prognostic impact of SOX2 and OCT3/4 expression on adult acute leukemia patients' outcomes.

METHODS

SOX2 and OCT3/4 expression by blast cells were evaluated by flow cytometry in 80 acute leukemia patients and 8 healthy controls.

RESULTS

Baseline SOX2 and OCT3/4 expression were significantly higher in both ALL (P = < 0.001, P = 0.005 respectively) and AML patients (P < 0.001, P = 0.003 respectively) as compared to control, and decline at complete remission (CR) and elevated again at relapse. High SOX2 and OCT3/4 levels were significantly correlated with the presence of adverse risk stratification parameters.

CONCLUSION

Our findings indicated that both SOX2 and OCT3/4 could serve as biomarkers that could improve risk stratification of acute leukemia patients. Also, both SOX2 and OCT3/4 might be a therapeutic target, especially in resistant acute leukemia.

Knocking down SOX2 overcomes the resistance of prostate cancer to castration via notch signaling

BACKGROUND

Castration-resistant prostate cancer (CRPC) is a terminal type of advanced cancer resistant to androgen deprivation therapy (ADT). Due to the poor therapeutic response of CRPC, novel treatment strategies are urgently required. This study aimed to clarify the regulatory roles of the SOX2/Notch axis in CRPC.

METHODS

For the evaluation of the SOX2, Notch, and Hey1 expression in the prostate cancer (PCa) and CRPC tissues, we conducted immunohistochemistry (IHC) analyses. RT-PCR, Western blotting, and immunofluorescence were performed to evaluate SOX2 and Notch expression in enzalutamide-resistant LNCaP cells (Enza-R). CCK-8, Transwell, Wound healing, and Western blotting assays were used to assess the viability, invasion, migration, cell cycle, and drug-resistant in Enza-R cells.

RESULTS

Compared to the PCa tissues, CRPC tissues exhibited significantly elevated SOX2, Notch1, and Hey1 expression. SOX2-positive patients were more likely to develop bone metastases than SOX2-negative ones. Significant activation of the signaling associated with SOX2 and Notch was detected in Enza-R cells. The suppression of SOX2 clearly inactivated the Notch signaling and inhibited malignant behaviors, including proliferation, invasion, migration, and drug resistance in Enza-R cells. Theγsecretase inhibitor, GSI-IX, abrogated the enzalutamide resistance by inhibiting Notch signaling in vitro in vitro. Also, GSI-IX alone had a significant anti-tumor effect in Enza-R cells.

CONCLUSION

We demonstrated that SOX2/Notch signaling was responsible for Enzalutamide resistance in CRPC. Targeting SOX2/Notch signaling might represent a new choice for the treatment and therapy of CRPC.

Targeting the SOX2/CDP protein complex with a peptide suppresses the malignant progression of esophageal squamous cell carcinoma

Emerging evidence indicates that SOX2 is an oncogene for esophageal squamous cell carcinoma (ESCC). However, direct targeting of SOX2 is not feasible given that this transcription factor plays important roles in the maintenance of tissues such as the brain. Here, we identified CDP (Homeobox protein cut-like 1 or CASP) as a unique SOX2 binding partner enriched in ESCC with Duolink proximity ligation assay, bimolecular fluorescence complementation (BiFc) and immunoprecipitation. We then screened a peptide aptamer library using BiFc and immunoprecipitation and identified several peptide aptamers, including P58, that blocked the CDP/SOX2 interaction, leading to the inhibition of ESCC progress in vitro and in vivo. Upon administration, synthetic peptide P58, containing the YGRKKRRQRRR cell-penetrating peptide and the fluorophore TAMRA, also blocked the growth and metastasis of ESCC in both mice and zebrafish. Therefore, targeting the SOX2 binding partner CDP with peptide P58 offers an alternative avenue to treat ESCC with increased SOX2 levels.

Targeting redox regulation and autophagy systems in cancer stem cells

Cancer is a dysregulated cellular level pathological condition that results in tumor formation followed by metastasis. In the heterogeneous tumor architecture, cancer stem cells (CSCs) are essential to push forward the progression of tumors due to their strong pro-tumor properties such as stemness, self-renewal, plasticity, metastasis, and being poorly responsive to radiotherapy and chemotherapeutic agents. Cancer stem cells have the ability to withstand various stress pressures by modulating transcriptional and translational mechanisms, and adaptable metabolic changes. Owing to CSCs heterogeneity and plasticity, these cells display varied metabolic and redox profiles across different types of cancers. It has been established that there is a disparity in the levels of Reactive Oxygen Species (ROS) generated in CSCs vs Non-CSC and these differential levels are detected across different tumors. CSCs have unique metabolic demands and are known to change plasticity during metastasis by passing through the interchangeable epithelial and mesenchymal-like phenotypes. During the metastatic process, tumor cells undergo epithelial to mesenchymal transition (EMT) thus attaining invasive properties while leaving the primary tumor site, similarly during the course of circulation and extravasation at a distant organ, these cells regain their epithelial characteristics through Mesenchymal to Epithelial Transition (MET) to initiate micrometastasis. It has been evidenced that levels of Reactive Oxygen Species (ROS) and associated metabolic activities vary between the epithelial and mesenchymal states of CSCs. Similarly, the levels of oxidative and metabolic states were observed to get altered in CSCs post-drug treatments. As oxidative and metabolic changes guide the onset of autophagy in cells, its role in self-renewal, quiescence, proliferation and response to drug treatment is well established. This review will highlight the molecular mechanisms useful for expanding therapeutic strategies based on modulating redox regulation and autophagy activation to targets. Specifically, we will account for the mounting data that focus on the role of ROS generated by different metabolic pathways and autophagy regulation in eradicating stem-like cells hereafter referred to as cancer stem cells (CSCs).

Overexpression of SOX2 Gene by Histone Modifications: SOX2 Enhances Human Prostate and Breast Cancer Progression by Prevention of Apoptosis and Enhancing Cell Proliferation

INTRODUCTION

SOX2 plays a crucial role in tumor development, cancer stem cell maintenance, and cancer progression. Mechanisms of SOX2 gene regulation in human breast and prostate cancers are not established yet.

METHODS

SOX2 expression in prostate and breast cancer tissues and cell lines was determined by qRT-PCR, Western blot, and immunochemistry, followed by the investigation of pro-tumorigenic properties like cell proliferation, migration, and apoptosis by gene knockdown and treatment with epigenetic modulators and ChIP.

RESULTS

Prostate and breast cancer tissues showed very high expression of SOX2. All cancer cell lines DU145 and PC3 (prostate) and MCF7 and MDA-MB-231 (breast) exhibited high expression of SOX2. Inhibition of SOX2 drastically decreased cell proliferation and migration. Epigenetic modulators enhanced SOX2 gene expression in both cancer types. DNA methylation pattern in SOX2 promoter could not be appreciably counted for SOX2 overexpression. Activation of SOX2 gene promoter was due to very high deposition of H3K4me3 and H3K9acS10p and drastic decrease of H3K9me3 and H3K27me3.

CONCLUSION

Histone modification is crucial for the overexpression of SOX2 during tumor development and cancer progression. These findings show the avenue of co-targeting SOX2 and its active epigenetic modifier enzymes to effectively treat aggressive prostate and breast cancers.

Isoliensinine augments the therapeutic potential of paclitaxel in multidrug-resistant colon cancer stem cells and induced mitochondria-mediated cell death

Previously we have reported the isoliensinine (ISO) potentates the therapeutic potential of cisplatin in cisplatin resistant colorectal cancer stem cells. The present study evaluates the chemo-sensitizing potential of the combinatorial regimen of ISO and Paclitaxcel (PTX) on multidrug-resistant (MDR)-HCT-15 cells to reduce the dose requirement of both ISO and PTX. The results of the present study suggest that treatment with the combinatorial regimen of ISO and PTX enhanced the cytotoxic effect with resultant increase in apoptosis in MDR-HCT-15 cells as evident from the altered cellular morphology, G2/M cell cycle arrest, propidium iodide uptake, Annexin V, increased intracellular Ca2+ accumulation, decreased mitochondrial membrane potential, diminished ATP production, PARP-1 cleavage, altered expression of ERK1/2, and apoptotic proteins. Treatment with combinatorial regimen of ISO and PTX also modulated the expression of the transcription factors SOX2, OCT4 which determine the stemness of cancer cells. Thus, results of the present study suggest that ISO and PTX combination regimen induces apoptosis in MDR-HCT-15 in a synergistic manner.

Crosstalk between SOX Genes and Long Non-Coding RNAs in Glioblastoma

Glioblastoma (GBM) continues to be the most devastating primary brain malignancy. Despite significant advancements in understanding basic GBM biology and enormous efforts in developing new therapeutic approaches, the prognosis for most GBM patients remains poor with a median survival time of 15 months. Recently, the interplay between the SOX (SRY-related HMG-box) genes and lncRNAs (long non-coding RNAs) has become the focus of GBM research. Both classes of molecules have an aberrant expression in GBM and play essential roles in tumor initiation, progression, therapy resistance, and recurrence. In GBM, SOX and lncRNAs crosstalk through numerous functional axes, some of which are part of the complex transcriptional and epigenetic regulatory mechanisms. This review provides a systematic summary of current literature data on the complex interplay between SOX genes and lncRNAs and represents an effort to underscore the effects of SOX/lncRNA crosstalk on the malignant properties of GBM cells. Furthermore, we highlight the significance of this crosstalk in searching for new biomarkers and therapeutic approaches in GBM treatment.

PVT1/miR-136/Sox2/UPF1 axis regulates the malignant phenotypes of endometrial cancer stem cells

Tumor stem cells (TSCs) are thought to contribute to the progression and maintenance of cancer. Previous studies have suggested that plasmacytoma variant translocation 1 (PVT1) has a tumor-promoting effect on endometrial cancer; however, its mechanism of action in endometrial cancer stem cells (ECSCs) is unknown. Here, we found that PVT1 was highly expressed in endometrial cancers and ECSCs, correlated with poor patient prognosis, promoted the malignant behavior and the stemness of endometrial cancer cells (ECCs) and ECSCs. In contrast, miR-136, which was lowly expressed in endometrial cancer and ECSCs, had the opposite effect, and knockdown miR-136 inhibited the anticancer effects of down-regulated PVT1. PVT1 affected miR-136 specifically binding the 3' UTR region of Sox2 by competitively "sponging" miR-136, thus positively saving Sox2. Sox2 promoted the malignant behavior and the stemness of ECCs and ECSCs, and overexpression Sox2 inhibited the anticancer effects of up-regulated miR-136. Sox2 can act as a transcription factor to positively regulate Up-frameshift protein 1 (UPF1) expression, thereby exerting a tumor-promoting effect on endometrial cancer. In nude mice, simultaneously downregulating PVT1 and upregulating miR-136 exerted the strongest antitumor effect. We demonstrate that the PVT1/miR-136/Sox2/UPF1 axis plays an important role in the progression and maintenance of endometrial cancer. The results suggest a novel target for endometrial cancer therapies.

SOX2 inhibits LLGL2 polarity protein in esophageal squamous cell carcinoma via miRNA-142-3p

ABBREVIATIONS

CCK-8, Cell Counting Kit 8; Chip, Chromatin Immunoprecipitation; EC, Esophageal cancer; EMT, epithelial-to-mesenchymal transition; ESCC, Esophageal squamous cell carcinomas; LLGL2, lethal (2) giant larvae protein homolog 2; LLGL2ov, LLGL2 overexpression; MET, mesenchymal-epithelial transition; miRNAs, MicroRNAs; PRM-MS, Parallel reaction monitoring-Mass spectrometry; SD, Standard deviation; SOX, sex determining region Y (SRY)-like box; SOX2-Kd, SOX2-knockdwon; TUNEL, TdT-mediated dUTP Nick-End Labeling.

SOX2 como posible biomarcador pronóstico y diana molecular en el cáncer de pulmón: metaanálisis

OBJECTIVE

To determine the association of SOX2 with the prognosis in lung cancer, studies providing survival information were selected based on multivariate Cox regression analysis.

MATERIAL AND METHODS

PubMed, Embase, and Web of Science databases were searched to identify eligible studies before June 19, 2021. The hazard ratios (HR) with 95% confidence intervals (CI) were calculated to assess the prognostic impact of SOX2 based on multivariate Cox regression analysis. Publication bias was used to assess the risk of bias. Functional analysis of SOX2 was also conducted.

RESULTS

13 studies with a total of 2008 patients with lung cancer were included. SOX2 expression was not correlated with overall survival in lung cancer (10 studies with 1591 cases). Between-study heterogeneity was noted (I²=85.6%, p<0.0001). Subgroup analysis suggested that no correlation was found between SOX2 expression and overall survival in non-small cell lung cancer (NSCLC: eight studies with 1319 cases) and small-cell lung cancer (SCLC: two studies with 272 cases). SOX2 expression was significantly associated with worse time-to-progression (two studies with 104 cases: HR=3.50, 95% CI=1.34-9.15) and recurrence-free survival (two studies with 335 cases: HR=1.45, 95% CI=1.12-1.87) in NSCLC. Function analysis demonstrated that SOX2 was involved in DNA repair, cell cycle, regulation of stem cell population maintenance, and Hippo signaling pathway.

CONCLUSION

SOX2 may be an independent prognostic factor in time-to-progression and recurrence-free survival and may become a promising therapeutic target. More studies are essential to further our findings.

Signaling pathways and targeted therapies in lung squamous cell carcinoma: mechanisms and clinical trials

Lung cancer is the leading cause of cancer-related death across the world. Unlike lung adenocarcinoma, patients with lung squamous cell carcinoma (LSCC) have not benefitted from targeted therapies. Although immunotherapy has significantly improved cancer patients' outcomes, the relatively low response rate and severe adverse events hinder the clinical application of this promising treatment in LSCC. Therefore, it is of vital importance to have a better understanding of the mechanisms underlying the pathogenesis of LSCC as well as the inner connection among different signaling pathways, which will surely provide opportunities for more effective therapeutic interventions for LSCC. In this review, new insights were given about classical signaling pathways which have been proved in other cancer types but not in LSCC, including PI3K signaling pathway, VEGF/VEGFR signaling, and CDK4/6 pathway. Other signaling pathways which may have therapeutic potentials in LSCC were also discussed, including the FGFR1 pathway, EGFR pathway, and KEAP1/NRF2 pathway. Next, chromosome 3q, which harbors two key squamous differentiation markers SOX2 and TP63 is discussed as well as its related potential therapeutic targets. We also provided some progress of LSCC in epigenetic therapies and immune checkpoints blockade (ICB) therapies. Subsequently, we outlined some combination strategies of ICB therapies and other targeted therapies. Finally, prospects and challenges were given related to the exploration and application of novel therapeutic strategies for LSCC.

A fungicide, fenhexamid, is involved in the migration and angiogenesis in breast cancer cells expressing estrogen receptors

Fenhexamid (Fen) is used to eradicate gray mold of fruits and vegetables leading to greater detection of its residual concentration in wine than other fungicides. Here, we further investigated the malign influence of Fen on the migration and angiogenesis via regulation of the estrogen receptor (ER) and phosphoinositide 3-kinase (PI3K) pathways in breast cancer models. ER-positive MCF-7 and ER-negative MDA-MB-231 breast cancer cells were exposed to 17β-estradiol (E2, 10^-9 M), Fen (10^-5 M and 10^-7 M), ICI 182,780 (ICI; an ER antagonist, 10^-8 M) or/and Pictilisib (Pic; a PI3K inhibitor, 10^-7 M), and subsequently subjected to migration assay, live cell motility monitoring, trans-chamber assay, immunofluorescence, angiogenesis assay, tumor spheroid formation, and Western blot analysis. In MCF-7 cells, E2 and Fen induced cell migration by regulating the cell migration-related proteins. Although expressions of N-cadherin and Vimentin remained unchanged E2 and Fen induced the decrease of E-cadherin and Occludin in the immunofluorescence assay and Western blot analysis. In addition, Fen increased vessel formation in HUVEC cells. Furthermore, Fen treatment induced the formation of larger and denser tumor spheroids in MCF-7 cells. Western blot further confirmed the increased expressions of vascular endothelial growth factor (VEGF) and sex-determining region Y-box 2 (SOX2) after exposure to Fen. We conclude that Fen plays an important role as an endocrine-disrupting chemical in breast cancer migration and metastasis through the regulation of ER and PI3K signaling pathways.

Differential Gene Expression and Weighted Correlation Network Dynamics in High-Throughput Datasets of Prostate Cancer

Precision oncology is an absolute need today due to the emergence of treatment resistance and heterogeneity among cancerous profiles. Target-propelled cancer therapy is one of the treasures of precision oncology which has come together with substantial medical accomplishment. Prostate cancer is one of the most common cancers in males, with tremendous biological heterogeneity in molecular and clinical behavior. The spectrum of molecular abnormalities and varying clinical patterns in prostate cancer suggest substantial heterogeneity among different profiles. To identify novel therapeutic targets and precise biomarkers implicated with prostate cancer, we performed a state-of-the-art bioinformatics study, beginning with analyzing high-throughput genomic datasets from The Cancer Genome Atlas (TCGA). Weighted gene co-expression network analysis (WGCNA) suggests a set of five dysregulated hub genes (MAF, STAT6, SOX2, FOXO1, and WNT3A) that played crucial roles in biological pathways associated with prostate cancer progression. We found overexpressed STAT6 and SOX2 and proposed them as candidate biomarkers and potential targets in prostate cancer. Furthermore, the alteration frequencies in STAT6 and SOX2 and their impact on the patients' survival were explored through the cBioPortal platform. The Kaplan-Meier survival analysis suggested that the alterations in the candidate genes were linked to the decreased overall survival of the patients. Altogether, the results signify that STAT6 and SOX2 and their genomic alterations can be explored in therapeutic interventions of prostate cancer for precision oncology, utilizing early diagnosis and target-propelled therapy.

Targeting the SOX2/PARP1 complex to intervene in the growth of esophageal squamous cell carcinoma

Elevated SOX2 protein levels are closely correlated with the increased incidence of esophageal squamous cell carcinoma (ESCC). However, establishing effective target measures for ESCC treatments continue to be researched. It has been previously proposed that SOX2 represents a potential therapeutic target for ESCC. Here, we found that the enzyme Poly(ADP-Ribose) polymerase 1 (PARP1) enriched in ESCCs interact with SOX2. Inhibition of PARP1 with 3-aminobenzamide (3-ABA) or shRNA knockdown reduced the proliferation of ESCCs, accompanied by decreased protein levels of SOX2. RNA sequencing demonstrated that PARP1 inhibition affected multiple signaling pathways involved in cancer cell proliferation. Additionally, 3-ABA synergistically suppressed the growth of ESCC cells when combined with cisplatin, and metformin potentiated the suppressive effect of 3-ABA on ESCC cell growth. Together these findings suggest that targeting SOX2 binding partner PARP1 provides a possible avenue to treat patients with high levels of SOX2.

SOX2 knockdown with siRNA reverses cisplatin resistance in NSCLC by regulating APE1 signaling

SOX2 is related to drug resistance in many types of cancer, including lung cancer. Herein, we investigated the role of SOX2 and its regulatory signaling in cisplatin-treated non-small-cell lung cancer (NSCLC). The effects of SOX2 on cell viability, proliferation, and apoptosis were evaluated in vitro. Western blotting, real-time quantitative PCR, immunohistochemistry, and luciferase reporter assays were used to investigate the underlying mechanism. Kaplan-Meier survival analysis and the log-rank test were used to assess the relationship between SOX2 expression and patient survival. A549/CDDP cells had marked resistance to cisplatin and stronger colony formation ability than A549 cells. The expression of SOX2 protein or mRNA in A549/CDDP was higher than that in A549. Knockdown of SOX2 in A549/CDDP-induced apoptosis by inhibiting colony formation and decreasing viability, but overexpression of SOX2 reversed these effects. Interestingly, Genomatix software predicted that the APE1 promoter has some SOX2 binding sites, while the SOX2 promoter has no APE1 binding sites. Furthermore, luciferase reporter assays proved that SOX2 could bind the promoter of APE1 in 293T cells. We further verified that SOX2 expression was not affected by shAPE1 in A549/CDDP. As expected, colony formation was obviously inhibited and apoptosis was strongly enhanced in A549/CDDP treated with SOX2 siSOX2 alone or combined with CDDP compared with control cells. Meaningfully, patients with low expression of SOX2, and even including its regulating APE1, survived longer than those with high expression of SOX2, and APE1. siSOX2 overcomes cisplatin resistance by regulating APE1 signaling, providing a new target for overcoming cisplatin resistance in NSCLC.

ROS Promote Hypoxia-Induced Keratinocyte Epithelial-Mesenchymal Transition by Inducing SOX2 Expression and Subsequent Activation of Wnt/β-Catenin

We previously showed that wound-induced hypoxia is related to keratinocyte migration. The ability of keratinocytes within wound healing to undergo epithelial to mesenchymal transition (EMT) contributes significantly to the acquisition of migratory properties. However, the effect of hypoxia on keratinocyte EMT on wound healing and the potential mechanism are poorly documented. This study first demonstrated that reactive oxygen species (ROS) appear to be an essential signalling mediator in keratinocytes with increased EMT and migration subjected to hypoxic conditions. Next, we showed that the expression of sex-determining region Y-box 2 (SOX2), a stemness-associated molecule, is ROS-dependent under hypoxia and that SOX2 inhibition in keratinocytes dramatically prevented hypoxia-induced EMT and migration. In addition, β-catenin was found to be a potential molecular target of SOX2, and the activation of Wnt/β-catenin was required for hypoxia-induced EMT and migration. Using an in vitro skin culture model and an in vivo skin wound model, our study further reinforced the critical role of ROS in inducing EMT through SOX2 expression and subsequent activation of Wnt/β-catenin, allowing for rapid reepithelialization of the wound area. Taken together, our findings reveal a previously unknown mechanism by which hypoxia promotes wound healing by promoting reepithelialization through the production of ROS, inducing keratinocyte EMT and migration via the enhancement of SOX2 and activation of Wnt/β-catenin.

Spindle pole body component 24 homolog potentiates tumor progression via regulation of SRY-box transcription factor 2 in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most common pathological subtype of human kidney cancer with a high probability of metastasis. To understand the molecular processing essential for ccRCC tumorigenicity, we conducted an integrative in silico analysis of The Cancer Genome Atlas (TCGA) ccRCC dataset and clustered randomly interspersed short palindromic repeats (CRISPR) screening dataset of ccRCC cell lines from Depmap. We identified spindle pole body component 24 homolog (SPC24) as an essential gene for ccRCC cell lines with prognostic significance in the TCGA database. Targeting SPC24 by CRISPR/Cas9-mediated gene knockout attenuated ccRCC proliferation, metastasis, and in vivo tumor growth. Furthermore, we found that SPC24 regulates metastasis genes expression in a SRY-box transcription factor 2 (SOX2)-dependent manner. The anti-proliferative effects of SPC24 knockout were strengthened with SOX2 knockdown. Collectively, our findings suggest SPC24 has a pivotal function in promoting ccRCC progression, providing a new insight for the treatment of ccRCC.

The Impact of Iron Chelators on the Biology of Cancer Stem Cells

Neoplastic diseases are still a major medical challenge, requiring a constant search for new therapeutic options. A serious problem of many cancers is resistance to anticancer drugs and disease progression in metastases or local recurrence. These characteristics of cancer cells may be related to the specific properties of cancer stem cells (CSC). CSCs are involved in inhibiting cells’ maturation, which is essential for maintaining their self-renewal capacity and pluripotency. They show increased expression of transcription factor proteins, which were defined as stemness-related markers. This group of proteins includes OCT4, SOX2, KLF4, Nanog, and SALL4. It has been noticed that the metabolism of cancer cells is changed, and the demand for iron is significantly increased. Iron chelators have been proven to have antitumor activity and influence the expression of stemness-related markers, thus reducing chemoresistance and the risk of tumor cell progression. This prompts further investigation of these agents as promising anticancer novel drugs. The article presents the characteristics of stemness markers and their influence on the development and course of neoplastic disease. Available iron chelators were also described, and their effects on cancer cells and expression of stemness-related markers were analyzed.

Engineered Bacteriorhodopsin May Induce Lung Cancer Cell Cycle Arrest and Suppress Their Proliferation and Migration

Highly expressible bacteriorhodopsin (HEBR) is a light-triggered protein (optogenetic protein) that has seven transmembrane regions with retinal bound as their chromophore to sense light. HEBR has controllable photochemical properties and regulates activity on proton pumping. In this study, we generated HEBR protein and incubated with lung cancer cell lines (A549 and H1299) to evaluate if there was a growth-inhibitory effect with or without light illumination. The data revealed that the HEBR protein suppressed cell proliferation and induced the G0/G1 cell cycle arrest without light illumination. Moreover, the migration abilities of A549 and H1299 cells were reduced by ~17% and ~31% after incubation with HEBR (40 μg/mL) for 4 h. The Snail-1 gene expression level of the A549 cells was significantly downregulated by ~50% after the treatment of HEBR. In addition, HEBR significantly inhibited the gene expression of Sox-2 and Oct-4 in H1299 cells. These results suggested that the HEBR protein may inhibit cell proliferation and cell cycle progression of lung cancer cells, reduce their migration activity, and suppress some stemness-related genes. These findings also suggested the potential of HEBR protein to regulate the growth and migration of tumor cells, which may offer the possibility for an anticancer drug.

Luteolin attenuates cancer cell stemness in PTX-resistant oesophageal cancer cells through mediating SOX2 protein stability

Cancer drug resistance is a formidable obstacle that enhances cancer stem-like cell properties, tumour metastasis and relapse. Luteolin (Lut) is a natural flavonoid with strong antitumor effects. However, the underlying mechanism(s) by which Lut protects against paclitaxel-resistant (PTX-resistant) cancer cell remains unknown. Herein, we found that Lut significantly attenuated the stem-like properties of PTX-resistant cancer cells by downregulating the expression of SOX2 protein. Additionally, further study showed that Lut could inhibit the PI3K/AKT pathway to decrease the phosphorylation level of AKT(S473) and UBR5 expression, which is an ubiquitin E3 ligase that promotes SOX2 degradation. In addition, Lut also inhibited PTX-resistant cancer cell migration and invasion by blocking epithelial-mesenchymal transition (EMT). Importantly, Lut inhibited the tumorigenic ability of oesophageal PTX-resistant cancer cells and showed no obvious toxicity in vivo. Thus, Lut has potential as a promising agent for drug-resistant oesophageal cancer therapy.

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.

MicroRNAs and Stem-like Properties: The Complex Regulation Underlying Stemness Maintenance and Cancer Development

Embryonic stem cells (ESCs) have the extraordinary properties to indefinitely proliferate and self-renew in culture to produce different cell progeny through differentiation. This latter process recapitulates embryonic development and requires rounds of the epithelial-mesenchymal transition (EMT). EMT is characterized by the loss of the epithelial features and the acquisition of the typical phenotype of the mesenchymal cells. In pathological conditions, EMT can confer stemness or stem-like phenotypes, playing a role in the tumorigenic process. Cancer stem cells (CSCs) represent a subpopulation, found in the tumor tissues, with stem-like properties such as uncontrolled proliferation, self-renewal, and ability to differentiate into different cell types. ESCs and CSCs share numerous features (pluripotency, self-renewal, expression of stemness genes, and acquisition of epithelial-mesenchymal features), and most of them are under the control of microRNAs (miRNAs). These small molecules have relevant roles during both embryogenesis and cancer development. The aim of this review was to recapitulate molecular mechanisms shared by ESCs and CSCs, with a special focus on the recently identified classes of microRNAs (noncanonical miRNAs, mirtrons, isomiRs, and competitive endogenous miRNAs) and their complex functions during embryogenesis and cancer development.

Targeting therapy-resistant lung cancer stem cells via disruption of the AKT/TSPYL5/PTEN positive-feedback loop

Cancer stem cells (CSCs) are regarded as essential targets to overcome tumor progression and therapeutic resistance; however, practical targeting approaches are limited. Here, we identify testis-specific Y-like protein 5 (TSPYL5) as an upstream regulator of CSC-associated genes in non-small cell lung cancer cells, and suggest as a therapeutic target for CSC elimination. TSPYL5 elevation is driven by AKT-dependent TSPYL5 phosphorylation at threonine-120 and stabilization via inhibiting its ubiquitination. TSPYL5-pT120 also induces nuclear translocation and functions as a transcriptional activator of CSC-associated genes, ALDH1 and CD44. Also, nuclear TSPYL5 suppresses the transcription of PTEN, a negative regulator of PI3K signaling. TSPYL5-pT120 maintains persistent CSC-like characteristics via transcriptional activation of CSC-associated genes and a positive feedback loop consisting of AKT/TSPYL5/PTEN signaling pathway. Accordingly, elimination of TSPYL5 by inhibiting TSPYL5-pT120 can block aberrant AKT/TSPYL5/PTEN cyclic signaling and TSPYL5-mediated cancer stemness regulation. Our study suggests TSPYL5 be an effective target for therapy-resistant cancer.

In order to assist the development of cancer stem cell (CSC) therapy, Kim et al identified testis-specific Y-like protein 5 (TSPYL5) as an upstream regulator of CSC-associated genes in non-small cell lung cancer cells. They demonstrated in cancer cell lines and in vivo that TSPYL5 activity is dependent on AKT signalling and that disruption of TSPYL5 signalling could serve as a potential strategy to tackle therapy-resistant cancers.

Pluripotency inducing Yamanaka factors: role in stemness and chemoresistance of liver cancer

Introduction: Liver cancer is a major cause of mortality and is characterized by the transformation of cells into an uncontrolled mass of tumor cells with many genetic and epigenetic changes, which lead to the development of tumors. A small subpopulation of cell population known as Cancer Stem Cells (CSCs) is responsible for cancer stemness and chemoresistance. Yamanaka factors [octamer-binding transcription factor 4 (OCT4), SRY (sex-determining region Y)-box 2 (SOX2), kruppel-like factor 4 (KLF4), and Myelocytomatosis (MYC); OSKM] are responsible for cancer cell stemness, chemoresistance, and recurrence.Area covered: We cover recent discoveries and investigate the role of OSKM in inducing pluripotency and stem cell-like properties in various cancers with special emphasis on liver cancer. We review Yamanaka factors' role in stemness and chemoresistance of liver cancer.Expert opinion: In CSCs, including liver CSCs, the deregulation of various signaling pathways is one of the major reasons for stemness and drug resistance and is primarily due to OSKM. OSKM are responsible for tumor heterogeneity which renders targeting drug useless after a certain period. These factors can be exploited to understand the underlying mechanism of cancer stemness and resistance to chemotherapeutic drugs.

Nectin-4 and p95-ErbB2 cooperatively regulate Hippo signaling-dependent SOX2 gene expression, enhancing anchorage-independent T47D cell proliferation

Nectin-4, upregulated in various cancer cells, cis-interacts with ErbB2 and its trastuzumab-resistant splice variants, p95-ErbB2 and ErbB2∆Ex16, enhancing DNA synthesis through the PI3K-AKT signaling in human breast cancer T47D cells in an adherent culture. We found here that nectin-4 and p95-ErbB2, but not nectin-4 and either ErbB2 or ErbB2∆Ex16, cooperatively enhanced SOX2 gene expression and cell proliferation in a suspension culture. This enhancement of T47D cell proliferation in a suspension culture by nectin-4 and p95-ErbB2 was dependent on the SOX2 gene expression. In T47D cells, nectin-4 and any one of p95-ErbB2, ErbB2, or ErbB2∆Ex16 cooperatively activated the PI3K-AKT signaling, known to induce the SOX2 gene expression, to similar extents. However, only a combination of nectin-4 and p95-ErbB2, but not that of nectin-4 and either ErbB2 or ErbB2∆Ex16, cooperatively enhanced the SOX2 gene expression. Detailed studies revealed that only nectin-4 and p95-ErbB2 cooperatively activated the Hippo signaling. YAP inhibited the SOX2 gene expression in this cell line and thus the MST1/2-LATS1/2 signaling-mediated YAP inactivation increased the SOX2 gene expression. These results indicate that only the combination of nectin-4 and p95-ErbB2, but not that of nectin-4 and either ErbB2 or ErbB2∆Ex16, cooperatively regulates the Hippo signaling-dependent SOX2 gene expression, enhancing anchorage-independent T47D cell proliferation.

Anti-oncogenic effects of SOX2 silencing on hepatocellular carcinoma achieved by upregulating miR-222-5p-dependent CYLD via the long noncoding RNA CCAT1

In this study, we determined the involvement of SOX2 and its downstream signaling molecules in hepatocellular carcinoma (HCC) progression. We carried out lentiviral transfection in HepG2 cells to determine the roles of SOX2, CCAT1, EGFR, miR-222-5p, and CYLD in HepG2 cells. We first determined the interaction between SOX2 and CCAT1 and that between miR-222-5p and CYLD and their effect on tumor growth in vivo was analyzed in HCC-xenograft bearing nude mice xenografts. SOX2 and CCAT1 were highly expressed in HCC tissues and HepG2 cells. SOX2 bound to the regulatory site of CCAT1. Silencing of SOX2 or CCAT1 inhibited HepG2 cell proliferation, migration, and invasion as well as decreased the expression of CCAT1 and EGFR. CCAT1 silencing reduced EGFR expression, but EGFR expression was increased in HCC tissues and HepG2 cells, which promoted proliferation, migration, and invasion in vitro. EGFR upregulated miR-222-5p, leading to downregulation of CYLD. miR-222-5p inhibition or CYLD overexpression repressed cell functions in HepG2 cells. SOX2 silencing decreased CCAT1, EGFR, and miR-222-5p expression but increased CYLD expression. Loss of SOX2 also reduced the growth rate of tumor xenografts. In summary, SOX2-mediated HCC progression through an axis involving CCAT1, EGFR, and miR-222-5p upregulation and CYLD downregulation.

Targeting the Sonic Hedgehog Pathway to Suppress the Expression of the Cancer Stem Cell (CSC)-Related Transcription Factors and CSC-Driven Thyroid Tumor Growth

Simple Summary

Poorly differentiated and anaplastic thyroid cancers respond poorly to surgery, radiation, and hormone therapy. Cancer stem cells play an important role in tumor growth, drug resistance, and recurrence. This study focuses on how the sonic hedgehog (Shh) pathway maintains thyroid cancer stem cell self-renewal and whether it can be targeted for anticancer therapy. The authors report that the Shh pathway regulates the expression of BMI1 and SOX2, two genes involved in stem cell self-renewal, and that targeting the Shh pathway has little effect on thyroid tumor xenografts but can inhibit the growth of tumor xenografts derived from thyroid cancer stem cells. This study advances the knowledge on how thyroid cancer stem cells regenerate and highlights the potential therapeutic values of targeting the Shh pathway.

Abstract

The sonic hedgehog (Shh) pathway plays important roles in tumorigenesis, tumor growth, drug resistance, and metastasis. We and others have reported earlier that this pathway is highly activated in thyroid cancer. However, its role in thyroid cancer stem cell (CSC) self-renewal and tumor development remains incompletely understood. B lymphoma Mo-MLV insertion region 1 homolog (BMI1) and SRY-Box Transcription Factor 2 (SOX2) are two CSC-related transcription factors that have been implicated in promoting CSC self-renewal. The objective of our current investigation was to determine the role of the Shh pathway in regulating BMI1 and SOX2 expression in thyroid cancer and promoting thyroid tumor growth and development. Here we report that inhibition of the Shh pathway by Gli1 siRNA or by cyclopamine and GANT61 reduced BMI1 and SOX2 expression in SW1736 and KAT-18 cells, two anaplastic thyroid cancer cell lines. The opposite results were obtained in cells overexpressing Gli1 or its downstream transcription factor Snail. The Shh pathway regulated SOX2 and BMI1 expression at a transcriptional and post-transcriptional level, respectively. GANT61 treatment suppressed the growth of SW1736 CSC-derived tumor xenografts but did not significantly inhibit the growth of tumors grown from bulk tumor cells. Clinicopathological analyses of thyroid tumor specimens by immunohistochemical (IHC) staining revealed that BMI1 and SOX2 were highly expressed in thyroid cancer and correlated with Gli1 expression. Our study provides evidence that activation of the Shh pathway leads to increased BMI1 and SOX2 expression in thyroid cancer and promotes thyroid CSC-driven tumor initiation. Targeting the Shh pathway may have therapeutic value for treating thyroid cancer and preventing recurrence.

Chrysin serves as a novel inhibitor of DGKα/FAK interaction to suppress the malignancy of esophageal squamous cell carcinoma (ESCC)

Among current novel druggable targets, protein–protein interactions (PPIs) are of considerable and growing interest. Diacylglycerol kinase α (DGKα) interacts with focal adhesion kinase (FAK) band 4.1-ezrin-radixin-moesin (FERM) domain to induce the phosphorylation of FAK Tyr397 site and promotes the malignant progression of esophageal squamous cell carcinoma (ESCC) cells. Chrysin is a multi-functional bioactive flavonoid, and possesses potential anticancer activity, whereas little is known about the anticancer activity and exact molecular mechanisms of chrysin in ESCC treatment. In this study, we found that chrysin significantly disrupted the DGKα/FAK signalosome to inhibit FAK-controlled signaling pathways and the malignant progression of ESCC cells both in vitro and in vivo, whereas produced no toxicity to the normal cells. Molecular validation specifically demonstrated that Asp435 site in the catalytic domain of DGKα contributed to chrysin-mediated inhibition of the assembly of DGKα/FAK complex. This study has illustrated DGKα/FAK complex as a target of chrysin for the first time, and provided a direction for the development of natural products-derived PPIs inhibitors in tumor treatment.

Remodeling cancer stemness by collagen/fibronectin via the AKT and CDC42 signaling pathway crosstalk in glioma

Cancer development is a complex set of proliferative progression, which arises in most cases via multistep pathways associated with various factors, including the tumor microenvironment and extracellular matrix. However, the underlying mechanisms of cancer development remain unclear and this study aimed to explore the role of extracellular matrix in glioma progression.

Methods: The expression of type I collagen and fibronectin in tumor tissues from glioma patients was examined by immunofluorescence staining. The correlations between collagen/fibronectin and glioma progression were then analyzed. A 3D collagen/fibronectin cultured system was established for tumor cells culture in vitro. Quantitative, real-time PCR and western blot were used to detect PI3K/ATK and CDC42 signals associated proteins expression in glioma. We used in vitro Cell Counting Kit-8, colony formation, and tumorigenesis assays to investigate the function of PI3K/AKT and CDC42 signals associated proteins. A xenograft glioma mice model was also used to study the anticancer effects of integrin inhibitor in vivo.

Results: Our study demonstrated that type I collagen and fibronectin collaborate to regulate glioma cell stemness and tumor growth. In a 3D collagen/fibronectin culture model, glioma cells acquired tumorigenic potential and revealed strengthened proliferative characteristics. More significantly, collagen/fibronectin could facilitate the activation of PI3K/AKT/SOX2 and CDC42/YAP-1/NUPR1/Nestin signaling pathways via integrin αvβ3, eliciting sustained tumor growth and cancer relapse. Combination of the integrin signaling pathway inhibitor and the chemotherapeutic agent efficiently suppressed glioma cell proliferation and tumorigenic ability.

Conclusion: We demonstrated that type I collagen and fibronectin could collaborate to promote glioma progression through PI3K/AKT/SOX2 and CDC42/YAP-1/NUPR1/Nestin signaling pathways. Blockade of the upstream molecular integrin αvβ3 revealed improved outcome in glioma therapy, which provide new insights for eradicating tumors and reducing glioma cancer relapse.

Prognostic Implication of SOX2 Expression Associated with p16 in Oropharyngeal Cancer: A Study of Consecutive Tissue Microarrays and TCGA

Simple Summary

The role of human papillomavirus (HPV) in oropharyngeal cancer (OPSCC) as a cause agent has been reported in much of the literature. As a surrogate marker, p16 immunohistochemical staining is used as the standard for classifying OPSCC, and the prognosis of p16+ OPSCC has been reported to be better than p16− OPSCC. However, it was necessary to study what is the next biomarker that could predict the prognosis after classification by p16. We assumed that SOX2 may be a potential biomarker. For each p16+ and p16− OPSCC, SOX2 was used to analyze whether the degree of expression level differed in survival and recurrence rates. The results showed that both immunohistochemical staining and mRNA expression level of SOX2 significantly affected the survival and recurrence rates of p16+ OPSCC patients in two different datasets which were constructed in differently ways. Our study presented the clinical applicability of SOX2 as a biomarker.

Abstract

For oropharyngeal squamous cell carcinoma (OPSCC), there are not enough additional robust biomarkers for subgrouping after the distinct classification using p16. As SOX2 is an emerging biomarker for cancer treatment, its clinical implication in OPSCC was evaluated using a consecutive tissue microarray (TMA) cohort consisting of 111 patients who underwent surgery as an initial treatment from May 2002 to December 2016 and 79 patients in The Cancer Genome Atlas (TCGA) dataset. In both datasets, p16+/SOX2^High (HPV+/SOX2^High in TCGA) showed the best prognosis among the four groups classified by SOX2 and p16 for 5-year overall survival (OS) and recurrence (all p < 0.05), but SOX2 did not make a significant difference in the prognosis of the p16− group. In the TMA cohort, SOX2^High was significantly correlated with response to radiotherapy and lower pathologic T classification in the p16+ group (p = 0.001). In TCGA, correlations between SOX2 and tumor stage classification or radiotherapy were not observed; however, HPV+/SOX2^High had a significantly low tumor mutation burden among the four groups (all p < 0.05). In summary, SOX2 was proven to be a potential marker to predict overall survival and recurrence in p16+ OPSCC. However, the role of SOX2 has not yet been confirmed in p16− OPSCC patients.

SOX2-Upregulated microRNA-30e Promotes the Progression of Esophageal Cancer via Regulation of the USP4/SMAD4/CK2 Axis

Esophageal cancer (EC) is a highly aggressive disease, and its progression involves a complex gene regulation network. Transcription factor SOX2 is amplified in various cancers including EC. A pathway involving SOX2 regulation of microRNAs (miRNAs) and their target genes has been previously revealed. This study aims to delineate the ability of SOX2 to influence the EC progression, with the involvement of miR-30e/USP4/SMAD4/CK2 axis. SOX2 expression was first examined in the clinical tissue samples from 30 EC patients. Effects of SOX2 on proliferation, migration, and invasion alongside tumorigenicity of transfected cells were examined by means of gain- and loss-of-function experiments. EC tissues and cells exhibited high expression of SOX2, miR-30e, and CK2 and poor expression of USP4 and SMAD4. Mechanistically, SOX2 was positively correlated with miR-30e and upregulated the expression of miR-30e. miR-30e specifically targeted USP4, which induced deubiquitination of SMAD4 and promoted its expression. Meanwhile, SMAD4 was enriched in the CK2 promoter region and thus inhibited its expression. SOX2 stimulated EC cell proliferative, invasive, and migratory capacities in vitro and tumor growth in vivo by regulating the miR-30e/USP4/SMAD4/CK2 axis. Collectively, our work reveals a novel SOX2-mediated regulatory network in EC that may be a viable target for EC treatment.

microRNA-139-3p Inhibits Malignant Behaviors of Laryngeal Cancer Cells via the KDM5B/SOX2 Axis and the Wnt/β-Catenin Pathway

Background

Laryngeal cancer (LCA) is a common head and neck cancer. Lysine demethylase 5B (KDM5B) knockdown is expected as a new target for cancer prevention. We investigated the molecular mechanism of KDM5B in LCA.

Materials and Methods

The levels of KDM5B, microRNA (miR)-139-3p and high-mobility-group box 2 (SOX2) in LCA tissues and cells, normal tissues and cells were detected. The effect of KDM5B on LCA was evaluated. The upstream miR of KDM5B and the downstream gene and pathway of KDM5B were predicted and their effects on LCA were analyzed. The Wnt/β-catenin pathway-specific activator agonist was delivered into LCA cells expressing miR-139-3p mimic to evaluate the role of the Wnt/β-catenin pathway.

Results

KDM5B was highly expressed in LCA, and inhibition of KDM5B suppressed LCA progression. miR-139-3p, downregulated in LCA tissues, was a regulatory miR of KDM5B. Overexpression of miR-139-3p significantly inhibited the malignant biological behaviors of LCA cells. KDM5B promoted SOX2 expression via histone demethylation. SOX2 was highly expressed in LCA, and overexpression of SOX2 promoted LCA progression by inducing the Wnt/β-catenin pathway. Activated Wnt/β-catenin pathway attenuated the inhibitory effect of miR-139-3p mimic on the malignant biological behaviors of LCA cells.

Conclusion

miR-139-3p overexpression inhibited LCA development via regulating the KDM5B/SOX2 axis and inhibiting the Wnt/β-catenin pathway.

ZIC2 promotes cancer stem cell traits via up-regulating OCT4 expression in lung adenocarcinoma cells

Background: Accumulating evidence has revealed the importance of cancer stem cells (CSCs) in self-renewal and chemoresistance. Previous studies reported high expression of ZIC2 was closely associated with tumorigenesis and CSC traits. However, the role of ZIC2 as a crucial factor for regulating CSC properties in lung adenocarcinoma (LAC) remains elusive. Methods: RT-PCR and WB assay were employed to assess ZIC2 expression in 20 LAC tumor tissues and the matched non-cancerous tissues. The role of ZIC2 in LAC CSC were analyzed by evaluation of CSC-related markers expression and spheroid formation in vitro. Cisplatin and paclitaxel resistance capacities were evaluated by CCK8 assay, colony formation assay, and flow cytometry analysis. Subcutaneous NOD/SCID mice models were generated to assess in vivo CSC features. Results: High expression of ZIC2 was found in LAC tumor tissues and indicated a poor overall survival in LAC patients. ZIC2 upregulated an array of CSCs-related genes, including EpCAM, OCT4, SOX2, NANOG, C-Myc and Bmi-1. Knockdown of ZIC2 inhibited sphere-forming capacity and decreased cisplatin and paclitaxel resistance. However, overexpression of ZIC2 achieved opposite effects. Mechanically, ZIC2 acts upstream of OCT4 to promote its expression, resulting in enhancement of CSC traits in LAC. Conclusion: Our results demonstrated that ZIC2 was crucial for promoting CSC traits in LAC cells, and served as a potential biomarker for predicting prognosis. The ZIC2-OCT4 network will facilitate the evaluation of the potential therapeutic efficacy of chemotherapy and predict patient sensitivity to treatment.

Functional characterization of SOX2 as an anticancer target

SOX2 is a well-characterized pluripotent factor that is essential for stem cell self-renewal, reprogramming, and homeostasis. The cellular levels of SOX2 are precisely regulated by a complicated network at the levels of transcription, post-transcription, and post-translation. In many types of human cancer, SOX2 is dysregulated due to gene amplification and protein overexpression. SOX2 overexpression is associated with poor survival of cancer patients. Mechanistically, SOX2 promotes proliferation, survival, invasion/metastasis, cancer stemness, and drug resistance. SOX2 is, therefore, an attractive anticancer target. However, little progress has been made in the efforts to discover SOX2 inhibitors, largely due to undruggable nature of SOX2 as a transcription factor. In this review, we first briefly introduced SOX2 as a transcription factor, its domain structure, normal physiological functions, and its involvement in human cancers. We next discussed its role in embryonic development and stem cell-renewal. We then mainly focused on three aspects of SOX2: (a) the regulatory mechanisms of SOX2, including how SOX2 level is regulated, and how SOX2 cross-talks with multiple signaling pathways to control growth and survival; (b) the role of SOX2 in tumorigenesis and drug resistance; and (c) current drug discovery efforts on targeting SOX2, and the future perspectives to discover specific SOX2 inhibitors for effective cancer therapy.

Stem cell programs in cancer initiation, progression, and therapy resistance

Over the past few decades, substantial evidence has convincingly revealed the existence of cancer stem cells (CSCs) as a minor subpopulation in cancers, contributing to an aberrantly high degree of cellular heterogeneity within the tumor. CSCs are functionally defined by their abilities of self-renewal and differentiation, often in response to cues from their microenvironment. Biological phenotypes of CSCs are regulated by the integrated transcriptional, post-transcriptional, metabolic, and epigenetic regulatory networks. CSCs contribute to tumor progression, therapeutic resistance, and disease recurrence through their sustained proliferation, invasion into normal tissue, promotion of angiogenesis, evasion of the immune system, and resistance to conventional anticancer therapies. Therefore, elucidation of the molecular mechanisms that drive cancer stem cell maintenance, plasticity, and therapeutic resistance will enhance our ability to improve the effectiveness of targeted therapies for CSCs. In this review, we highlight the key features and mechanisms that regulate CSC function in tumor initiation, progression, and therapy resistance. We discuss factors for CSC therapeutic resistance, such as quiescence, induction of epithelial-to-mesenchymal transition (EMT), and resistance to DNA damage-induced cell death. We evaluate therapeutic approaches for eliminating therapy-resistant CSC subpopulations, including anticancer drugs that target key CSC signaling pathways and cell surface markers, viral therapies, the awakening of quiescent CSCs, and immunotherapy. We also assess the impact of new technologies, such as single-cell sequencing and CRISPR-Cas9 screening, on the investigation of the biological properties of CSCs. Moreover, challenges remain to be addressed in the coming years, including experimental approaches for investigating CSCs and obstacles in therapeutic targeting of CSCs.

The Clinical and Molecular Characteristics of Sex-Determining Region Y-Box 2 and its Prognostic Value in Breast Cancer: A Systematic Meta-Analysis

Objective

Transcription factor SOX2 (sex-determining region Y-box 2) has a crucial role in the maintenance of the stem cell state. However, current evidence regarding the role of SOX2 in breast cancer is conflicting. We conducted this meta-analysis to clarify the association of SOX2 expression with clinical and molecular features and its prognostic effect on breast cancer.

Methods

All relevant articles were searched using electronic databases. The pooled odds ratios (ORs) or hazard ratios (HRs: multivariate Cox survival analysis) with their 95% confidence intervals (CIs) were calculated.

Results

A final total of 18 studies containing 3,080 patients with breast cancer were included. SOX2 protein expression was not related to age, menopausal status, lymph node metastasis, lymphovascular invasion, molecular estrogen receptor status, progesterone receptor status, triple-negative status, and the overall survival in breast cancer, but was closely associated with advanced tumor grade (grade 3 vs. grade 1-2: OR = 2.74, 95% CI = 1.85-4.06, p < 0.001), clinical stage (stage 3-4 vs. stage 0-2: OR = 2.46, 95% CI = 1.37-4.40, p = 0.002), pT stage (T stage 2-4 vs. T stage 1: OR = 1.52, 95% CI = 1.07-2.17, p = 0.019), molecular human epidermal growth factor receptor 2 (HER2) status (positive vs. negative: OR = 1.61, 95% CI = 1.21-2.14, p = 0.001), epidermal growth factor receptor (EGFR) status (positive vs. negative: OR = 2.21, 95% CI = 1.13-4.33, p = 0.021), and worse disease-free survival (DFS) (HR = 2.66, 95% CI = 1.20-5.91, p = 0.016) of breast cancer.

Conclusions

SOX2 expression is correlated with breast cancer progression, HER2 status, and EGFR status, and may be an independent prognostic marker for predicting poor DFS.

The LSD1 inhibitor iadademstat (ORY-1001) targets SOX2-driven breast cancer stem cells: a potential epigenetic therapy in luminal-B and HER2-positive breast cancer subtypes

SOX2 is a core pluripotency-associated transcription factor causally related to cancer initiation, aggressiveness, and drug resistance by driving the self-renewal and seeding capacity of cancer stem cells (CSC). Here, we tested the ability of the clinically proven inhibitor of the lysine-specific demethylase 1 (LSD1/KDM1A) iadademstat (ORY-100) to target SOX2-driven CSC in breast cancer. Iadademstat blocked CSC-driven mammosphere formation in breast cancer cell lines that are dependent on SOX2 expression to maintain their CSC phenotype. Iadademstat prevented the activation of an LSD1-targeted stemness-specific SOX2 enhancer in CSC-enriched 3-dimensional spheroids. Using high-throughput transcriptional data available from the METABRIC dataset, high expression of SOX2 was significantly more common in luminal-B and HER2-enriched subtypes according to PAM50 classifier and in IntClust1 (high proliferating luminal-B) and IntClust 5 (luminal-B and HER2-amplified) according to integrative clustering. Iadademstat significantly reduced mammospheres formation by CSC-like cells from a multidrug-resistant luminal-B breast cancer patient-derived xenograft but not of those from a treatment-naïve luminal-A patient. Iadademstat reduced the expression of SOX2 in luminal-B but not in luminal-A mammospheres, likely indicating a selective targeting of SOX2-driven CSC. The therapeutic relevance of targeting SOX2-driven breast CSC suggests the potential clinical use of iadademstat as an epigenetic therapy in luminal-B and HER2-positive subtypes.

Clinical and Survival Impact of Sex-Determining Region Y-Box 2 in Colorectal Cancer: An Integrated Analysis of the Immunohistochemical Study and Bioinformatics Analysis

Transcription factor sex-determining region Y-box 2 (SOX2) involves in the maintenance of cancer stem cells. However, the role of SOX2 in colorectal cancer (CRC) remains unclear. This study was conducted to investigate the effect of SOX2 on CRC. Studies were searched using electronic databases. The combined odds ratios (ORs) or hazard ratios (HRs: multivariate Cox survival analysis) with their 95% confidence intervals (CIs) were calculated. The Cancer Genome Atlas (TCGA) and GEO datasets were further applied to validate the survival effect. The functional analysis of SOX2 was investigated. In this work, 13 studies including 2337 patients were identified, and validation data were enrolled from TCGA and GEO datasets. SOX2 expression was not significantly related to age, gender, microsatellite instability (MSI) status, clinical stage, histological grade, tumor size, pT-stage, lymph node metastasis, distal metastasis, and cancer-specific survival (CSS) but was correlated with worse overall survival (OS: n = 536 patients) (P < 0.05). Furthermore, TCGA data demonstrated similar results, with no significant correlation between SOX2 and pathological characteristics. Further validation data (OS: n = 1408 and disease-free survival (DFS): n = 1367) showed that SOX2 expression was correlated with worse OS (HR = 1.35, 95% CI: 1.11–1.65, P=0.004) and DFS (HR = 1.30, 95% CI: 1.04–1.62, P=0.02). The functional analyses showed that SOX2 involved in cell-cell junction, focal adhesion, extracellular matrix- (ECM-) receptor interaction, and MAP kinase activity. Our findings suggest that SOX2 expression may be correlated with the worse prognosis of CRC.