SOX2 and cancer: current research and its implications in the clinic

Identification of SOX6 and SOX12 as Prognostic Biomarkers for Clear Cell Renal Cell Carcinoma: A Retrospective Study Based on TCGA Database

Background

The SOX gene family has been proven to display regulatory effects on numerous diseases, particularly in the malignant progression of neoplasms. However, the molecular functions and action mechanisms of SOX genes have not been clearly elucidated in clear cell renal cell carcinoma (ccRCC). We aimed to explore the expression status, prognostic values, clinical significances, and regulatory actions of SOX genes in ccRCC.

Methods

RNA-sequence data and clinical information derived from The Cancer Genome Atlas (TCGA) database was used for this study. Dysregulated SOX genes between the normal group and ccRCC group were screened using the Wilcoxon signed-rank test. The Kaplan-Meier analysis and univariate Cox analysis methods were used to estimate the overall survival (OS) and disease-specific survival (DSS) differences between different groups. The independent prognostic factors were identified by the use of uni- and multivariate assays. Subsequently, the Wilcoxon signed-rank test or Kruskal-Wallis test and the chi-square test or Fisher exact probability methods were employed to explore the association between clinicopathological variables and SOX genes. Finally, CIBERSORT was applied to study the samples and examine the infiltration of immune cells between different groups.

Results

Herein, 12 dysregulated SOX genes in ccRCC were screened. Among them, two independent prognostic SOX genes (SOX6 and SOX12) were identified. Further investigation results showed that SOX6 and SOX12 were distinctly associated with clinicopathological features. Furthermore, functional enrichment analysis revealed that SOX6 and SOX12 were enriched in essential biological processes and signaling pathways. Finally, we found that the SOX6 and SOX12 expression levels were correlated with tumor-infiltrating immune cells (TIICs).

Conclusion

The pooled analyses showed that SOX6 and SOX12 could serve as promising biomarkers and therapeutic targets of patients with ccRCC.

Non-histone methylation of SET7/9 and its biological functions

BACKGROUND

(su(var)-3-9,enhancer-of-zeste,trithorax) domain-containing protein 7/9 (SET7/9) is a member of the protein lysine methyltransferases (PLMTs or PKMTs) family. It contains a SET domain. Recent studies demonstrate that SET7/9 methylates both lysine 4 of histone 3 (H3-K4) and lysine(s) of non-histone proteins, including transcription factors, tumor suppressors, and membrane-associated receptors.

OBJECTIVE

This article mainly reviews the non-histone methylation effects of SET7/9 and its functions in tumorigenesis and development.

METHODS

PubMed was screened for this information.

RESULTS

SET7/9 plays a key regulatory role in various biological processes such as cell proliferation, transcription regulation, cell cycle, protein stability, cardiac morphogenesis, and development. In addition, SET7/9 is involved in the pathogenesis of hair loss, breast cancer progression, human carotid plaque atherosclerosis, chronic kidney disease, diabetes, obesity, ovarian cancer, prostate cancer, hepatocellular carcinoma, and pulmonary fibrosis.

CONCLUSION

SET7/9 is an important methyltransferase, which can catalyze the methylation of a variety of proteins. Its substrates are closely related to the occurrence and development of tumors.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Clinical Significance and Prognostic Value of SOX2 Protein Expression in Patients With Oral Squamous Cell Carcinoma

OBJECTIVES

Cancer stem cells are a small group of highly tumorigenic cells with the trend of self-renewal, tumor progression, metastasis, recurrence, and therapeutic resistance. SOX2 is an important cancer stem cell marker that is involved in tumorigenesis and correlated with aggressive features in various types of malignancies. The present study was aimed to investigate the expression of this biomarker in neoplastic tissues of oral squamous cell carcinoma (OSCC) to determine whether it has the potential to predict the outcomes and survival of the affected patients.

MATERIALS AND METHODS

The medical records of 73 patients diagnosed with OSCC were retrospectively studied. Clinical and pathologic features included age, sex, tumor size, histologic grade, lymph node involvement, recurrence, metastasis, and follow up. Immunohistochemical analysis for SOX2 protein expression was performed, and its correlations with clinicopathologic features were evaluated.

RESULTS

SOX2 was significantly associated with tumor size, lymph node metastasis, and patients' survival. We found no apparent correlation between SOX2 and tumor recurrence, distant metastasis, or differentiation. The multivariate analysis identifies patients' age, sex, and SOX2 expression as independent prognostic factors for overall survival.

CONCLUSION

SOX2 may worsen the prognosis and be a progressive malignant factor, which can help clinicians investigate OSCC patients' survival and plan the appropriate treatment accordingly.

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.

Ascorbic Acid Inhibits Liver Cancer Growth and Metastasis in vitro and in vivo, Independent of Stemness Gene Regulation

Experimental and clinical evidence has indicated that the natural product ascorbic acid (AA) is effective in preventing and treating various types of cancers. However, the effect of AA on liver cancer metastasis has not yet been reported. Cancer stem cells (CSCs) play pivotal roles in cancer metastasis. Here, we demonstrated that AA selectively inhibited the viability of both liver cancer cells and CSCs, reduced the formation of cancer cell colonies and CSC spheres, and inhibited tumor growth in vivo. Additionally, AA prevented liver cancer metastasis in a xenotransplantation model without suppressing stemness gene expression in liver CSCs. Further study indicated that AA increased the concentration of H₂O₂ and induced apoptosis in liver CSCs. Catalase attenuated the inhibitory effects of AA on liver CSC viability. In conclusion, AA inhibited the viability of liver CSCs and the growth and metastasis of liver cancer cells in vitro and in vivo by increasing the production of H₂O₂ and inducing apoptosis. Our findings provide evidence that AA exerts its anti-liver cancer efficacy in vitro and in vivo, in a manner that is independent of stemness gene regulation.

Proliferation Increasing Genetic Engineering in Human Corneal Endothelial Cells: A Literature Review

The corneal endothelium is the inner layer of the cornea. Despite comprising only a monolayer of cells, dysfunction of this layer renders millions of people visually impaired worldwide. Currently, corneal endothelial transplantation is the only viable means of restoring vision for these patients. However, because the supply of corneal endothelial grafts does not meet the demand, many patients remain on waiting lists, or are not treated at all. Possible alternative treatment strategies include intracameral injection of human corneal endothelial cells (HCEnCs), biomedical engineering of endothelial grafts and increasing the HCEnC density on grafts that would otherwise have been unsuitable for transplantation. Unfortunately, the limited proliferative capacity of HCEnCs proves to be a major bottleneck to make these alternatives beneficial. To tackle this constraint, proliferation enhancing genetic engineering is being investigated. This review presents the diverse array of genes that have been targeted by different genetic engineering strategies to increase the proliferative capacity of HCEnCs and their relevance for clinical and research applications. Together these proliferation-related genes form the basis to obtain a stable and safe supply of HCEnCs that can tackle the corneal endothelial donor shortage.

miR-145-5p as a predictive biomarker for breast cancer stemness by computational clinical investigation

BACKGROUND

Breast tumors enriched with breast cancer stem cells (BCSCs), play a crucial role in metastasis and tumor relapse. Hence, targeting BCSCs may lead to efficacious breast cancer therapy. BCSCs have a unique expression of stemness markers, including Nanog, POU5F1, SOX2, and CD44, which play a vital role in cancer stem cell properties. However, the regulation of microRNAs (miRNAs)-mediated cancer stem cell marker expressions is largely unclear.

METHODS

MIENTURNET was used to predict miRNA-target interactions. miR-TV, UALCAN and GEPIA databases were used to analyze the expression of miR-145-5p and SOX2. Survival analysis was obtained by cBioportal, KM plotter and Breast Cancer Gene-Expression Miner. RNAComposer was used to perform miRNA-mRNA duplex prediction. In vitro mRNA and miRNA analysis was performed by qRT-PCR.

RESULTS

It was observed that miR-145-5p was the common miRNA targeting stemness markers. miR-145-5p expression was found to be lower in breast cancer patients compared to healthy subjects. Based on survival analysis, low expression of miR-145-5p and high expression of SOX2 led to a poor overall survival rate in breast cancer patients. Pathway enrichment analysis indicated that SOX2 was highly enriched with transcription factors. Moreover, SOX2 expression level was also upregulated in axillary metastatic lymph nodules. Further, in vitro ectopic expression of miR-145-5p by its mimic downregulated the SOX2 expression compared to the control mimic. Overall, SOX2 was a direct target for miR-145-5p as per the binding and minimal-free energy.

CONCLUSIONS

In this study, miR-145-5p targeting SOX2 was identified as a potential predictive biomarker for breast cancer stemness.

MSX2 inhibits the growth and migration of osteosarcoma cells by repressing SOX2

SRY (sex determining region Y)-box 2 (SOX2) plays a key role in the maintenance of stemness and resistance to drugs, whereas tumor necrosis factor (TNF)-α is essential for maintaining cancer cell proliferation and metastasis. Accumulation of muscle segment homeobox 2 (MSX2) leads to downregulation of SOX2 expression. Here, we explored the MSX2-SOX2-TNF-α signaling axis and its function in the tumor phenotypes of osteosarcoma cells. Colony formation assay, cell counting kit (CCK)-8 assay, and Flow cytometry were used to examine cell growth, viability, and death, respectively. Wound healing and Transwell invasive assay were employed to examine cell migratory and invasive activities, respectively. Western blotting and RT-qPCR were used to determine the protein and mRNA expressions of MSX2, SOX2, TNF-α, Bax, and matrix metalloproteinase-2 (MMP-2). Osteosarcoma clinical samples and cells showed lower levels of MSX2 than normal healthy control samples. Overexpression of MSX2 led to a reduced activity of SOX2 and TNF-α, whereas MSX2 depletion did not contribute to upregulated SOX2 levels. A gain-of-function experiment showed that osteosarcoma cell viability and growth were reduced, cell death was increased, and migration and invasion were inhibited in the MSX2 overexpression group compared with those in the non-transfected group. Furthermore, co-overexpression of MSX2 and SOX2 counteracted the inhibitory effects of MSX2 on the abovementioned tumor phenotypes of osteosarcoma cells. An in vivo tumor growth assay showed that MSX2 overexpression slowed the growth rate of osteosarcoma xenograft tumors. Thus, MSX2 loss plays a crucial role in the osteosarcoma phenotype by elevating SOX2 and TNF-α levels.

Random survival forests identify pathways with polymorphisms predictive of survival in KRAS mutant and KRAS wild-type metastatic colorectal cancer patients

KRAS status serves as a predictive biomarker of response to treatment in metastatic colorectal cancer (mCRC). We hypothesize that complex interactions between multiple pathways contribute to prognostic differences between KRAS wild-type and KRAS mutant patients with mCRC, and aim to identify polymorphisms predictive of clinical outcomes in this subpopulation. Most pathway association studies are limited in assessing gene–gene interactions and are restricted to an individual pathway. In this study, we use a random survival forests (RSF) method for identifying predictive markers of overall survival (OS) and progression-free survival (PFS) in mCRC patients treated with FOLFIRI/bevacizumab. A total of 486 mCRC patients treated with FOLFIRI/bevacizumab from two randomized phase III trials, TRIBE and FIRE-3, were included in the current study. Two RSF approaches were used, namely variable importance and minimal depth. We discovered that Wnt/β-catenin and tumor associated macrophage pathway SNPs are strong predictors of OS and PFS in mCRC patients treated with FOLFIRI/bevacizumab independent of KRAS status, whereas a SNP in the sex-differentiation pathway gene, DMRT1, is strongly predictive of OS and PFS in KRAS mutant mCRC patients. Our results highlight RSF as a useful method for identifying predictive SNPs in multiple pathways.

Heparanase 2 (Hpa2) attenuates tumor growth by inducing Sox2 expression

The pro-tumorigenic properties of heparanase are well documented, and heparanase inhibitors are being evaluated clinically as anti-cancer therapeutics. In contrast, the role of heparanase 2 (Hpa2), a close homolog of heparanase, in cancer is largely unknown. Previously, we have reported that in head and neck cancer, high levels of Hpa2 are associated with prolonged patient survival and decreased tumor cell dissemination to regional lymph nodes, suggesting that Hpa2 functions to restrain tumorigenesis. Also, patients with high levels of Hpa2 were diagnosed as low grade and exhibited increased expression of cytokeratins, an indication that Hpa2 promotes or maintains epithelial cell differentiation and identity. To reveal the molecular mechanism underlying the tumor suppressor properties of Hpa2, and its ability to induce the expression of cytokeratin, we employed overexpression as well as gene editing (Crispr) approaches, combined with gene array and RNAseq methodologies. At the top of the list of many genes found to be affected by Hpa2 was Sox2. Here we provide evidence that silencing of Sox2 resulted in bigger tumors endowed with reduced cytokeratin levels, whereas smaller tumors were developed by cells overexpressing Sox2, suggesting that in head and neck carcinoma, Sox2 functions to inhibit tumor growth. Notably, Hpa2-null cells engineered by Crispr/Cas 9, produced bigger tumors vs control cells, and rescue of Hpa2 attenuated tumor growth. These results strongly imply that Hpa2 functions as a tumor suppressor in head and neck cancer, involving Sox2 upregulation mediated, in part, by the high-affinity interaction of Hpa2 with heparan sulfate.

Hyperbaric oxygen promotes not only glioblastoma proliferation but also chemosensitization by inhibiting HIF1α/HIF2α-Sox2

There exists a consensus that combining hyperbaric oxygen (HBO) and chemotherapy promotes chemotherapy sensitivity in GBM cells. However, few studies have explored the mechanism involved. HIF1α and HIF2α are the two main molecules that contribute to GBM malignant progression by inhibiting apoptosis or maintaining stemness under hypoxic conditions. Moreover, Sox2, a marker of stemness, also contributes to GBM malignant progression through stemness maintenance or cell cycle arrest. Briefly, HIF1α, HIF2α and Sox2 are highly expressed under hypoxia and contribute to GBM growth and chemoresistance. However, after exposure to HBO for GBM, whether the expression of the above factors is decreased, resulting in chemosensitization, remains unknown. Therefore, we performed a series of studies and determined that the expression of HIF1α, HIF2α and Sox2 was decreased after HBO and that HBO promoted GBM cell proliferation through cell cycle progression, albeit with a decrease in stemness, thus contributing to chemosensitization via the inhibition of HIF1α/HIF2α-Sox2.

Therapeutic Strategies for Targeting Ovarian Cancer Stem Cells

Ovarian cancer is a fatal gynecological malignancy. Although first-line chemotherapy and surgical operation are effective treatments for ovarian cancer, its clinical management remains a challenge owing to intrinsic or acquired drug resistance and relapse at local or distal lesions. Cancer stem cells (CSCs) are a small subpopulation of cells inside tumor tissues, and they can self-renew and differentiate. CSCs are responsible for the cancer malignancy involved in relapses as well as resistance to chemotherapy and radiation. These malignant properties of CSCs are regulated by cell surface receptors and intracellular pluripotency-associated factors triggered by internal or external stimuli from the tumor microenvironment. The malignancy of CSCs can be attenuated by individual or combined restraining of cell surface receptors and intracellular pluripotency-associated factors. Therefore, targeted therapy against CSCs is a feasible therapeutic tool against ovarian cancer. In this paper, we review the prominent roles of cell surface receptors and intracellular pluripotency-associated factors in mediating the stemness and malignancy of ovarian CSCs.

Reporters of Cancer Stem Cells as a Tool for Drug Discovery

In view of the importance of cancer stem cells (CSCs) in chemoresistance, metastasis and recurrence, the biology of CSCs were explored in detail. Based on that, several modalities were proposed to target them. In spite of the several clinical trials, a successful CSC-targeting drug is yet to be identified. The number of molecules screened and entered for clinical trial for CSC-targeting is comparatively low, compared to other drugs. The bottle neck is the lack of a high-throughput adaptable screening strategy for CSCs. This review is aimed to identify suitable reporters for CSCs that can be used to identify the heterogeneous CSC populations, including quiescent CSCs, proliferative CSCs, drug resistant CSCs and metastatic CSCs. Analysis of the tumor microenvironment regulating CSCs revealed that the factors in CSC-niche activates effector molecules that function as CSC markers, including pluripotency markers, CD133, ABCG2 and ALDH1A1. Among these factors OCT4, SOX2, NANOG, ABCG2 and ALDH1A1 are ideal for making reporters for CSCs. The pluripotency molecules, like OCT4, SOX2 and NANOG, regulate self-renewal, chemoresistance and metastasis. ABCG2 is a known regulator of drug resistance while ALDH1A1 modulates self-renewal, chemoresistance and metastasis. Considering the heterogeneity of CSCs, including a quiescent population and a proliferative population with metastatic ability, we propose the use of a combination of reporters. A dual reporter consisting of a pluripotency marker and a marker like ALDH1A1 will be useful in screening drugs that target CSCs.

Co-expression of SOX2 and HR-HPV RISH predicts poor prognosis in small cell neuroendocrine carcinoma of the uterine cervix

BACKGROUND

Small cell neuroendocrine carcinoma of the uterine cervix (SCNEC) is a rare cancer involving the human papilloma virus (HPV), and has few available treatments. The present work aimed to assess the feasibility of SOX2 and HPV statuses as predictive indicators of SCNEC prognosis.

METHODS

The associations of SOX2 and/or high-risk (HR)-HPV RNA in situ hybridization (RISH) levels with clinicopathological characteristics and prognostic outcomes for 88 neuroendocrine carcinoma (NEC) cases were analyzed.

RESULTS

Among these patients with SCNEC, SOX2, P16INK4A and HR-HPV RISH expression and SOX2/HR-HPV RISH co-expression were detected in 68(77.3%), 76(86.4%), 73(83.0%), and 48(54.5%), respectively. SOX2-positive and HR-HPV RISH-positive SCNEC cases were associated with poorer overall survival (OS, P = 0.0170, P = 0.0451) and disease-free survival (DFS, P = 0.0334, P = 0.0309) compared with those expressing low SOX2 and negative HR-HPV RISH. Alternatively, univariate analysis revealed that SOX2 and HR-HPV RISH expression, either separately or in combination, predicted the poor prognosis of SCNEC patients. Multivariate analysis revealed that the co-expression of SOX2 with HR-HPV RISH may be an independent factor of OS [hazard ratio = 3.597; 95% confidence interval (CI): 1.085-11.928; P = 0.036] and DFS [hazard ratio = 2.880; 95% CI: 1.199-6.919; P = 0.018] prediction in SCNEC.

CONCLUSIONS

Overall, the results of the present study suggest that the co-expression of SOX2 with HR-HPV RISH in SCNEC may represent a specific subgroup exhibiting remarkably poorer prognostic outcomes compared with the expression of any one marker alone.

HIF1α/HIF2α-Sox2/Klf4 promotes the malignant progression of glioblastoma via the EGFR-PI3K/AKT signalling pathway with positive feedback under hypoxia

Previous studies have suggested that hypoxic responses are regulated by hypoxia-inducible factors (HIFs), which in turn promote the malignant progression of glioblastoma (GBM) by inhibiting apoptosis and increasing proliferation; these events lead to a poor prognosis of GBM patients. However, there are still no HIF-targeted therapies for the treatment of GBM. We have conducted series of experiments and discovered that GBM cells exhibit features indicative of malignant progression and are present in a hypoxic environment. Knocking out HIF1α or HIF2α alone resulted in no significant change in cell proliferation and cell cycle progression in response to acute hypoxia, but cells showed inhibition of stemness expression and chemosensitization to temozolomide (TMZ) treatment. However, simultaneously knocking out HIF1α and HIF2α inhibited cell cycle arrest and promoted proliferation with decreased stemness, making GBM cells more sensitive to chemotherapy, which could improve patient prognosis. Thus, HIF1α and HIF2α regulate each other with negative feedback. In addition, HIF1α and HIF2α are upstream regulators of epidermal growth factor (EGF), which controls the malignant development of GBM through the EGFR-PI3K/AKT-mTOR-HIF1α signalling pathway. In brief, the HIF1α/HIF2α-EGF/EGFR-PI3K/AKT-mTOR-HIF1α signalling axis contributes to the growth of GBM through a positive feedback mechanism. Finally, HIF1α and HIF2α regulate Sox2 and Klf4, contributing to stemness expression and inducing cell cycle arrest, thus increasing malignancy in GBM. In summary, HIF1α and HIF2α regulate glioblastoma malignant progression through the EGFR-PI3K/AKT pathway via a positive feedback mechanism under the effects of Sox2 and Klf4, which provides a new tumour development model and strategy for glioblastoma treatment.

Microarray-based Analysis of Genes, Transcription Factors, and Epigenetic Modifications in Lung Cancer Exposed to Nitric Oxide

BACKGROUND/AIM

Nitric oxide (NO) is recognized as an important biological mediator that exerts several human physiological functions. As its nature is an aqueous soluble gas that can diffuse through cells and tissues, NO can affect cell signaling, the phenotype of cancer and modify surrounding cells. The variety of effects of NO on cancer cell biology has convinced researchers to determine the defined mechanisms of these effects and how to control this mediator for a better understanding as well as for therapeutic gain.

MATERIALS AND METHODS

We used bioinformatics and pharmacological experiments to elucidate the potential regulation and underlying mechanisms of NO in non-small a lung cancer cell model.

RESULTS

Using microarrays, we identified a total of 151 NO-regulated genes (80 up-regulated genes, 71 down-regulated genes) with a strong statistically significant difference compared to untreated controls. Among these, the genes activated by a factor of more than five times were: DCBLD2, MGC24975, RAB40AL, PER3, RCN1, MRPL51, PTTG1, KLF5, NFIX. On the other hand, the expression of RBMS2, PDP2, RBAK, ORMDL2, GRPEL2, ZNF514, MTHFD2, POLR2D, RCBTB1, JOSD1, RPS27, GPR4 genes were significantly decreased by a factor of more than five times. Bioinformatics further revealed that NO exposure of lung cancer cells resulted in a change in transcription factors (TFs) and epigenetic modifications (histone modification and miRNA). Interestingly, NO treatment was shown to potentiate cancer stem cell-related genes and transcription factors Oct4, Klf4, and Myc.

CONCLUSION

Through this comprehensive approach, the present study illustrated the scheme of how NO affects molecular events in lung cancer cells.

SOX2 in cancer stemness: tumor malignancy and therapeutic potentials

Cancer stem cells (CSCs), a minor subpopulation of tumor bulks with self-renewal and seeding capacity to generate new tumors, posit a significant challenge to develop effective and long-lasting anti-cancer therapies. The emergence of drug resistance appears upon failure of chemo-/radiation therapy to eradicate the CSCs, thereby leading to CSC-mediated clinical relapse. Accumulating evidence suggests that transcription factor SOX2, a master regulator of embryonic and induced pluripotent stem cells, drives cancer stemness, fuels tumor initiation, and contributes to tumor aggressiveness through major drug resistance mechanisms like epithelial-to-mesenchymal transition, ATP-binding cassette drug transporters, anti-apoptotic and/or pro-survival signaling, lineage plasticity, and evasion of immune surveillance. Gaining a better insight and comprehensive interrogation into the mechanistic basis of SOX2-mediated generation of CSCs and treatment failure might therefore lead to new therapeutic targets involving CSC-specific anti-cancer strategies.

Downregulation of SOX2 by inhibition of Usp9X induces apoptosis in melanoma

Melanoma tumors driven by BRAF mutations often do not respond to BRAF/MEK/ERK pathway inhibitors currently used in treatment. One documented mechanism of resistance is upregulation of SOX2, a transcription factor that is essential for tumor growth and expansion, particularly in melanoma tumors with BRAF mutations. Targeting transcription factors pharmacologically has been elusive for drug developers, limiting treatment options. Here we show that ubiquitin-specific peptidase 9, X-linked (Usp9x), a deubiquitinase (DUB) enzyme controls SOX2 levels in melanoma. Usp9x knockdown in melanoma increased SOX2 ubiquitination, leading to its depletion, and enhanced apoptotic effects of BRAF inhibitor and MEK inhibitors. Primary metastatic melanoma samples demonstrated moderately elevated Usp9x and SOX2 protein expression compared to tumors without metastatic potential. Usp9x knockdown, as well as inhibition with DUB inhibitor, G9, blocked SOX2 expression, suppressed in vitro colony growth, and induced apoptosis of BRAF-mutant melanoma cells. Combined treatment with Usp9x and mutant BRAF inhibitors fully suppressed melanoma growth in vivo. Our data demonstrate a novel mechanism for targeting the transcription factor SOX2, leveraging Usp9x inhibition. Thus, development of DUB inhibitors may add to the limited repertoire of current melanoma treatments.

SOX1 Is a Backup Gene for Brain Neurons and Glioma Stem Cell Protection and Proliferation

Failed neuroprotection leads to the initiation of several diseases. SOX1 plays many roles in embryogenesis, oncogenesis, and male sex determination, and can promote glioma stem cell proliferation, invasion, and migration due to its high expression in glioblastoma cells. The functional versatility of the SOX1 gene in malignancy, epilepsy, and Parkinson's disease, as well as its adverse effects on dopaminergic neurons, makes it an interesting research focus. Hence, we collate the most important discoveries relating to the neuroprotective effects of SOX1 in brain cancer and propose hypothesis worthy of SOX1's role in the survival of senescent neuronal cells, its roles in fibroblast cell proliferation, and cell fat for neuroprotection, and the discharge of electrical impulses for homeostasis. Increase in electrical impulses transmitted by senescent cells affects the synthesis of neurotransmitters, which will modify the brain cell metabolism and microenvironment.

IL20RA signaling enhances stemness and promotes the formation of an immunosuppressive microenvironment in breast cancer

Rationale: Tumor microenvironment interacts with tumor cells to regulate their stemness properties through various cytokines and cytokine receptors. Previous studies revealed the possible role of interleukin 20 receptor subunit alpha (IL20RA) signaling in the progression of several types of tumors. However, its regulatory effects on the stemness and the microenvironment of breast cancer need to be studied.

Methods: Immunohistochemical staining and western blot analysis were used to evaluate the association between IL20RA and SOX2 in breast tumors and noncancerous tissues. Enzyme-linked immunosorbent assay and TCGA dataset analysis were performed to determine the function of IL20RA signaling in breast cancer progression. Gain- and loss-of-function methods were performed to examine the effects of IL20RA on the stemness of breast cancer cells. The stemness features were analyzed by detecting the expression of core stemness genes, side population (SP), sphere formation ability, and aldehyde dehydrogenase (ALDH) activity. Flow cytometric analysis was applied to detect the changes of tumor-infiltration lymphocytes in tumor tissues in mice. Based on the relevant molecular mechanisms elucidated in this study, a novel IL20RA-targeted liposomal nanoparticle encapsulating the signal transducer and activator of transcription 3 (STAT3) inhibitor stattic (NP-Stattic-IL20RA) was synthesized. These NPs were combined with anti-programmed death ligand 1 (PD-L1) antibody and chemotherapy to inhibit the development of breast tumors in mice.

Results: IL20RA is highly expressed in human breast cancers and is positively associated with the SOX2 expression. IL20RA increases the SP and ALDH^br proportions of breast cancer cells, enhances the sphere formation ability, and promotes the expression of core stemness genes, such as Sox2 and Oct4, as well as increases chemoresistance of breast cancer cells. IL20RA promotes the tumor-initiating ability and lung metastasis of breast cancer cells in vivo. In addition, IL20RA activates the Janus kinase 1 (JAK1)-STAT3-SOX2 signaling pathway, leading to increased expression of PD-L1 and reduced recruitment of anti-cancer lymphocytes, including CD8⁺ T cells and natural killer cells. Meanwhile, IL20RA signaling enhances the proportion of myeloid-derived suppressor cells. Combined with anti-PD-L1 antibody and NPs-Stattic-IL20RA, the chemotherapeutic efficacy was increased in breast cancer mouse models in vivo.

Conclusion: Collectively, our results reveal that the IL20RA pathway is a novel signaling pathway involved in promoting the stemness features of breast cancer along with the formation of a tumor-favorable immune microenvironment. Targeting the IL20RA^hi population with STAT3 signaling inhibition combined with anti-PD-L1 antibody can increase the therapeutic efficacy of chemotherapeutic agents for breast cancer. This study thus introduces a promising novel strategy for breast cancer therapy.

The role of the stem cell epigenome in normal aging and rejuvenative therapy

Adult stem cells are ultimately responsible for the lifelong maintenance of regenerating of tissues during both homeostasis and following injury. Hence, the functional attrition of adult stem cells is thought to be an important driving factor behind the progressive functional decline of tissues and organs that is observed during aging. The mechanistic cause underlying this age-associated exhaustion of functional stem cells is likely to be complex and multifactorial. However, it is clear that progressive remodeling of the epigenome and the resulting deregulation of gene expression programs can be considered a hallmark of aging, and is likely a key factor in mediating altered biological function of aged stem cells. In this review, we outline cell intrinsic and extrinsic mediators of epigenome remodeling during aging; discuss how such changes can impact on stem cell function; and describe how resetting the aged epigenome may rejuvenate some of the biological characteristics of stem cells.

Targeting interleukin-17 receptor B enhances gemcitabine sensitivity through downregulation of mucins in pancreatic cancer

Pancreatic cancer is the fourth leading cause of death worldwide due to its poorest prognoses with a 7% 5-year survival rate. Eighty percent of pancreatic cancer patients relapse after chemotherapy and develop early metastasis and drug resistance. Resistance to nucleoside analog gemcitabine frequently used in first-line therapy is an urgent issue in pancreatic cancer treatment. Expression of mucin (MUC) glycoproteins has been shown to enhance chemoresistance via increased cell stemness. Here we show interlukine-17 receptor B (IL-17RB) expression is positively correlated with MUC1 and MUC4 expression in pancreatic cancer cells and tumor tissue. Moreover, IL-17RB transcriptionally up-regulates expression of MUC1 and MUC4 to enhance cancer stem-like properties and resistance to gemcitabine. These results suggest IL-17RB can be a potential target for pancreatic cancer therapy. Indeed, treatment with IL-17RB-neutralizing antibody has a synergistic effect in combination with gemcitabine for killing pancreatic cancer cells. Altogether, these findings provide feasible applications for IL-17RB-targeting therapy in pancreatic cancer treatment.

Relevance of iNOS expression in tumor growth and maintenance of cancer stem cells in a bladder cancer model

The expression of inducible nitric oxide (NO) synthase (iNOS) in human bladder cancer (BC) is a poor prognostic factor associated with invasion and tumor recurrence. Here, we evaluated the relevance of iNOS expression in BC progression and in cancer stem cell (CSC) maintenance in a murine BC model. Also, iNOS expression and CSC markers were analyzed in human BC samples. iNOS inhibitors (L-NAME or 1400W) or shRNA were used on murine BC model with different iNOS expressions and invasiveness grades: MB49 (iNOS+, non-muscle invasive (NMI)) and MB49-I (iNOS++, muscle invasive (MI)), in order to analyzed cell proliferation, tumor growth, angiogenesis, number of CSC, and pluripotential marker expression. iNOS, SOX2, Oct4, and Nanog expressions were also analyzed in human BC samples by qPCR and immunohistochemistry. iNOS inhibtion reduced parameters associated with tumor progression and reduced the number of CSC, wich resulted higher in MB49-I than in MB49, in concordance with the higher expression of SOX2, Oct4, and Nanog. The expression of SOX2 was notoriously diminished, when iNOS was inhibited only in the MI cell line. Similar results were observed in human samples, where MI tumors expressed higher levels of iNOS and pluripotential genes, in comparison to NMI tumors with a positive correlation between those and iNOS, suggesting that iNOS expression is associated with CSC. iNOS plays an important role in BC progression and CSC maintenance. Its inhibition could be a potential therapeutic target to eradicate CSC, responsible for tumor recurrences. KEY MESSAGES: • iNOS expression is involved in bladder tumor development, growth, and angiogenesis. • iNOS expression is involved in bladder cancer stem cell generation and maintenance, playing an important role regulating their self-renewal capacity, especially in muscle invasive murine bladder cancer cells. • iNOS expression is higher in human muscle invasive tumors, in association with a high expression of pluripotential genes, especially of SOX2.

Expression of stem cell markers in stroma of odontogenic cysts and tumors

BACKGROUND

The stroma of odontogenic cysts/tumors may confer them differential biological behavior. We aimed to investigate the immunoexpression of stem cell markers (Nanog, SOX2, Oct4, and CD34) in the stroma of odontogenic cysts and tumors. CD34 was investigated exclusively as a marker for stromal fibroblast/fibrocyte cells (CD34 + SFCs). CD34 + SFCs were also investigated ultrastructurally.

METHODS

Ten cases each of primary odontogenic keratocyst (OKC), recurrent OKC, dentigerous cyst, ameloblastoma, unicystic ameloblastoma, odontogenic myxoma, and 7 syndromic OKC were included. Results were represented as the mean score (%) of positive cells/field for each marker for each study group. For CD34 + SFCs, results are presented as the mean number of cells/field for each type of lesion. Kruskal-Wallis and Spearman's correlation statistical tests were used; significance was set at P < .05.

RESULTS

All markers except Oct4 were expressed by stromal cells in all lesions. Expression of SOX2 was significantly higher in tumors than in cysts (P < .05). CD34 + SFCs were more frequent in cysts than in tumors. Ultrastructurally, CD34 + SFCs were identified for the first time in odontogenic lesions and showed characteristic bipolar/dendritic morphology.

CONCLUSION

Among examined stromal stem cell markers, only SOX2 distinguished tumors from cysts. CD34 + SFCs may also contribute to the biological behavior of odontogenic lesions.

Current and Future Trends in Molecular Biomarkers for Diagnostic, Prognostic, and Predictive Purposes in Non-Melanoma Skin Cancer

Skin cancer represents the most common type of cancer among Caucasians and presents in two main forms: melanoma and non-melanoma skin cancer (NMSC). NMSC is an umbrella term, under which basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and Merkel cell carcinoma (MCC) are found along with the pre-neoplastic lesions, Bowen disease (BD) and actinic keratosis (AK). Due to the mild nature of the majority of NMSC cases, research regarding their biology has attracted much less attention. Nonetheless, NMSC can bear unfavorable characteristics for the patient, such as invasiveness, local recurrence and distant metastases. In addition, late diagnosis is relatively common for a number of cases of NMSC due to the inability to recognize such cases. Recognizing the need for clinically and economically efficient modes of diagnosis, staging, and prognosis, the present review discusses the main etiological and pathological features of NMSC as well as the new and promising molecular biomarkers available including telomere length (TL), telomerase activity (TA), CpG island methylation (CIM), histone methylation and acetylation, microRNAs (miRNAs), and micronuclei frequency (MNf). The evaluation of all these aspects is important for the correct management of NMSC; therefore, the current review aims to assist future studies interested in exploring the diagnostic and prognostic potential of molecular biomarkers for these entities.

Deoxycholic Acid Upregulates the Reprogramming Factors KFL4 and OCT4 Through the IL-6/STAT3 Pathway in Esophageal Adenocarcinoma Cells

Cancer stem cells, a special subgroup of cancer cells, have self-renewal capabilities and multidirectional potential, which may be reprogrammed from the dedifferentiation of cancer cells, contributing to the failure of clinical treatments. Esophageal adenocarcinoma grows in an inflammatory environment stimulated by deoxycholic acid, an important component of gastroesophageal reflux content, contributing to the transformation of esophageal squamous epithelium to the precancerous lesions of esophageal adenocarcinoma, that is, Barrett esophagus. In the present study, deoxycholic acid was used to investigate whether it could induce the expression of reprogramming factors Krüppel-like factor, OCT4, and Nanog; the transformation to cancer stem cells in esophageal adenocarcinoma; and the involvement of the interleukin-6/signal transduction and activation of transcription 3 inflammatory signaling pathway. OE33 cells were treated with deoxycholic acid (250 μM) for 0 hour, 3 hours, 6 hours, and 12 hours before evaluating the messenger RNA expression of Krüppel-like factor, OCT4, Nanog, interleukin-6, and Bcl-xL by reverse transcription-quantitative polymerase chain reaction. Interleukin-6 protein was detected by enzyme linked immunosorbent assay, while signal transduction and activation of transcription 3, phosphorylated signal transduction and activation of transcription 3, Krüppel-like factor, and OCT4 were detected by Western blot. Signal transduction and activation of transcription 3 small interfering RNA and human recombinant interleukin-6 were used to treat OE33 cells and to detect their effects on Krüppel-like factor, OCT4, Nanog, CD44, hypoxia-inducible factor 1-α, and Bcl-xL expression. Results showed that deoxycholic acid promotes the expression of reprogramming factors Krüppel-like factor and OCT4, which are regulated by the interleukin-6/signal transduction and activation of transcription 3 signaling pathway. Deoxycholic acid has a malignancy-inducing effect on the transformation of esophageal adenocarcinoma stem cells, improving the antiapoptotic ability of tumors, and increasing the malignancy of esophageal adenocarcinoma. Deactivating the regulatory signaling pathway of interleukin-6/signal transduction and activation of transcription 3 and neutralizing deoxycholic acid may be novel targets for improving the clinical efficacy of esophageal adenocarcinoma therapy.

Cancer and SOX proteins: New insight into their role in ovarian cancer progression/inhibition

Transcription factors are potential targets in disease therapy, particularly in cancer. This is due to the fact that transcription factors regulate a variety of cellular events, and their modulation has opened a new window in cancer therapy. Sex-determining region Y (SRY)-related high-mobility group (HMG) box (SOX) proteins are potential transcription factors that are involved in developmental processes such as embryogenesis. It has been reported that abnormal expression of SOX proteins is associated with development of different cancers, particularly ovarian cancer (OC). In the present review, our aim is to provide a mechanistic review of involvement of SOX members in OC. SOX members may suppress and/or promote aggressiveness and proliferation of OC cells. Clinical studies have also confirmed the potential of transcription factors as diagnostic and prognostic factors in OC. Notably, studies have demonstrated the relationship between SOX members and other molecular pathways such as ST6Ga1-I, PI3K, ERK and so on, leading to more complexity. Furthermore, SOX members can be affected by upstream mediators such as microRNAs, long non-coding RNAs, and so on. It is worth mentioning that the expression of each member of SOX proteins is corelated with different stages of OC. Furthermore, their expression determines the response of OC cells to chemotherapy. These topics are discussed in this review to shed some light on role of SOX transcription factors in OC.

RCC2 Promotes Esophageal Cancer Growth by Regulating Activity and Expression of the Sox2 Transcription Factor

Regulator of chromosome condensation 2 (RCC2) is a protein located in the centrosome, which ensures that cell division proceeds properly. Previous reports show that RCC2 is overexpressed in some cancers and could play a key role in tumor development, but the mechanisms concerning how this occurs are not understood. Furthermore, no evidence exists regarding its role in esophageal cancer. We studied the relevance of RCC2 in esophageal cancer growth and its regulation on Sox2, an important transcription factor promoting esophageal cancer. RCC2 was overexpressed in esophageal tumors compared with normal tissue, and this overexpression was associated with tumorigenicity by increasing cell proliferation, anchorage-independent growth, and migration. These oncogenic effects were accompanied by overexpression of Sox2. RCC2 upregulated and stabilized Sox2 expression and its target genes by inhibiting ubiquitination-mediated proteasome degradation. Likewise, RCC2 increased the transcriptional activity and promoter binding of Sox2. In vivo studies indicated that RCC2 and Sox2 were overexpressed in esophageal tumors compared with normal tissue, and this upregulation occurs in the esophageal basal cell layer for both proteins. In conditional knockout mice, RCC2 deletion decreased the tumor nodule formation and progression in the esophagus compared with wild-type mice. Proliferating cell nuclear antigen expression, a cell proliferation marker, was also downregulated in RCC2 knockout mice. Overall, our data show for the first time that RCC2 is an important protein for the stabilization and transcriptional activation of Sox2 and further promotion of malignancy in esophageal cancer. IMPLICATIONS: This study shows that RCC2 controls Sox2 expression and transcriptional activity to mediate esophageal cancer formation.

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.

PAK5 promotes the cell stemness ability by phosphorylating SOX2 in lung squamous cell carcinomas

Growing evidences suggest that the overexpression of p21-activated kinase 5 (PAK5) plays an important role in various tumor progression. However, the role of PAK5 and its downstream target gene(s) in lung squamous cell carcinomas (LUSC) are waiting to be elucidated. TCGA data were utilized to evaluate the expression levels of PAK5 in LUSC. We then explored the role of PAK5 in maintaining the stem-like phenotype of lung squamous cancer cells through RT-PCR, flow cytometry, oncosphere-forming assay. In addition, co-immunoprecipitation, western blotting and immunofluorescence assays were used to determine SOX2 as a novel effector of PAK5. Xenograft models in nude mice were established to explore the roles of PAK5 in lung cancer growth. In this study, we have shown that PAK5 is overexpressed in LUSC tissues. The absence of PAK5 abolishes self-renewal ability of LUSC cells by decreasing the expression and phosphorylation of SOX2 in vitro and in vivo. In xenograft models, knockdown or pharmacological inhibition of PAK5 suppressed the tumor growth and metastasis of lung squamous cancer cells in vivo. Taken together, our findings suggest that the PAK5-mediated SOX2 phosphorylation promoted the cancer stem cell-like phenotype of LUSC cells. PAK5 inhibition may be a promising target in the treatment of SOX2 positive lung squamous cell cancer.

Docosahexaenoic acid (DHA) inhibits pro-angiogenic effects of breast cancer cells via down-regulating cellular and exosomal expression of angiogenic genes and microRNAs

AIMS

Docosahexaenoic acid (DHA) as an omega 3 free fatty acid has been reported to exert anti-angiogenesis effects. However, our current understanding regarding the precise mechanisms of such effects is still limited. Exosomes secreted by cancer cells may act as angiogenesis promoters. The aim of the study was to determine altered expression levels of HIF-1α, TGF-β, VEGFR, Snail1, Snail2 and SOX2 and their regulating microRNAs in MDA-MB-231 and BT-474 cell lines after treatment with DHA in both normoxic and hypoxic conditions.

MAIN METHODS

Human breast cancer cell lines including MDA-MB-231 and BT-474 were treated for 24 h with 100 uM DHA under normoxic and hypoxic conditions. Exosomes were isolated from untreated and treated cells and characterized by transmission electron microscopy (TEM) and western blotting. RNAs from cells and isolated exosomes were extracted and cDNAs were synthesized. Expression levels of miRNAs and their pro-angiogenic target genes were analyzed using quantitative real-time PCR (qRT-PCR).

KEY FINDINGS

We showed significant decrease in the expression of pro-angiogenic genes including HIF1-α, TGF-β, SOX2, Snail1, Snail2 and VEGFR in cells and also their secreted exosomes after treatment with DHA in normoxic and hypoxic conditions. Also the expression levels of tumor suppressor miRs including miR-101, miR-199, miR-342 were increased and the expression levels of oncomiRs including mir-382 and miR-21 were decreased after treatment with DHA in cells and exosomes.

SIGNIFICANCE

DHA can alter the expression of pro-angiogenic genes and microRNA contents in breast cancer cells and their derived-exosomes in favor of the inhibition of angiogenesis. Our data demonstrated new insight into DHA's anti-cancer action to target not only breast cancer cells but also their derived exosomes to suppress tumor angiogenesis.

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.

Two Sides of the Same Coin: The Role of Developmental pathways and pluripotency factors in normal mammary stem cells and breast cancer metastasis

Breast cancer initiation and progression are often observed as the result of dysregulation of normal developmental processes and pathways. Studies focused on normal mammary stem/progenitor cell activity have led to an understanding of how breast cancer cells acquire stemness-associated properties including tumor initiation, survival and multi-lineage differentiation into heterogeneous tumors that become difficult to target therapeutically. Importantly, more recent investigations have provided valuable insight into how key developmental regulators can impact multiple phases of metastasis, where they are repurposed to not only promote metastatic phenotypes such as migration, invasion and EMT at the primary site, but also to regulate the survival, initiation and maintenance of metastatic lesions at secondary organs. Herein, we discuss findings that have led to a better understanding of how embryonic and pluripotency factors contribute not only to normal mammary development, but also to metastatic progression. We further examine the therapeutic potential of targeting these developmental pathways, and discuss how a better understanding of compensatory mechanisms, crosstalk between pathways, and novel experimental models could provide critical insight into how we might exploit embryonic and pluripotency regulators to inhibit tumor progression and metastasis.

Integrated analysis revealing genome-wide chromosomal copy number variation in supraglottic laryngeal squamous cell carcinoma

Laryngeal squamous cell carcinoma (LSCC) is a genetically complex tumor type and one of the leading causes of cancer-associated disability and mortality. Genetic instability, such as chromosomal instability, is associated with the tumorigenesis of LSCC. Copy number variations (CNVs) have been demonstrated to contribute to the genetic diversity of tumor pathogenesis. Comparative genomic hybridization (CGH) has emerged as a high-throughput genomic technology that facilitates the aggregation of high-resolution data of cancer-associated genomic imbalances. In the present study, a total of 38 primary supraglottic LSCC cases were analyzed by high-resolution array-based CGH (aCGH) to improve the understanding of the genetic alterations in LSCC. Additionally, integration with bioinformatic analysis of microarray expression profiling data from the Gene Expression Omnibus (GEO) database provided a fundamental method for the identification of putative target genes. Genomic CNVs were detected in all cases. The size of net genomic imbalances per case ranged between a loss of 682.3 Mb (~24% of the genome) and a gain of 1,958.6 Mb (~69% of the genome). Recurrent gains included 2pter-q22.1, 3q26.1-qter, 5pter-p12, 7p22.3p14.1, 8p12p11.22, 8q24.13q24.3, 11q13.2q13.4, 12pter-p12.2, 18pter-p11.31 and 20p13p12.1, whereas recurrent losses included 3pter-p21.32, 4q28.1-q35.2, 5q13.2-qter, 9pter-p21.3 and monosomy 13. Gains of 3q26.1-qter were associated with tumor stage, poor differentiation and smoking history. Additionally, through integration with bioinformatic analysis of data from the GEO database, putative target oncogenes, including sex-determining region Y-box 2, eukaryotic translation initiation factor 4 gamma 1, fragile X-related gene 1, disheveled segment polarity protein 3, defective n cullin neddylation 1 domain containing 1, insulin like growth factor 2 mRNA binding protein 2 and CCDC26 long non-coding RNA, and tumor suppressor genes, such as CUB and sushi multiple domains 1, cyclin dependent kinase inhibitor 2A, protocadherin 20, serine peptidase inhibitor Kazal type 5 and Nei like DNA glycosylase 3, were identified in supraglottic LSCC. Supraglottic LSCC is a genetically complex tumor type and aCGH was demonstrated to be effective in the determination of molecular profiles with higher resolution. The present results enable the identification of putative target oncogenes and tumor suppressor gene mapping in supraglottic LSCC.

Heterogeneous genomic aberrations in esophageal squamous cell carcinoma: a review

Esophageal cancer (EC) causes hundreds of thousands of deaths a year worldwide, especially the major subtype esophageal squamous cell carcinoma (ESCC). With the advent of next-generation sequencing and the availability of commercial microarrays, abnormities in genetic levels have been revealed in various independent researches. High frequencies of structure variations (SVs), single nucleotide variations (SNVs) and copy-number alterations (CNAs) in ESCCs are uncovered, and ESCC shows high levels of inter- and intratumor heterogeneity, implying diverse evolutionary trajectories. This review tries to explain the pathogenesis of ESCC on the scope of most often mutated genes based on prior studies, hopes to offer some hints for diagnosis and therapy in clinic.

Pranlukast Antagonizes CD49f and Reduces Stemness in Triple-Negative Breast Cancer Cells

Introduction

Cancer stem cells (CSCs) drive the initiation, maintenance, and therapy response of breast tumors. CD49f is expressed in breast CSCs and functions in the maintenance of stemness. Thus, blockade of CD49f is a potential therapeutic approach for targeting breast CSCs. In the present study, we aimed to repurpose drugs as CD49f antagonists.

Materials and Methods

We performed consensus molecular docking using a subdomain of CD49f that is critical for heterodimerization and a collection of pharmochemicals clinically tested. Molecular dynamics simulations were employed to further characterize drug-target binding. Using MDA-MB-231 cells, we evaluated the effects of potential CD49f antagonists on 1) cell adhesion to laminin; 2) mammosphere formation; and 3) cell viability. We analyzed the effects of the drug with better CSC-selectivity on the activation of CD49f-downstream signaling by Western blot (WB) and co-immunoprecipitation. Expressions of the stem cell markers CD44 and SOX2 were analyzed by flow cytometry and WB, respectively. Transactivation of SOX2 promoter was evaluated by luciferase reporter assays. Changes in the number of CSCs were assessed by limiting-dilution xenotransplantation.

Results

Pranlukast, a drug used to treat asthma, bound to CD49f in silico and inhibited the adhesion of CD49f⁺ MDA-MB-231 cells to laminin, indicating that it antagonizes CD49f-containing integrins. Molecular dynamics analysis showed that pranlukast binding induces conformational changes in CD49f that affect its interaction with β1-integrin subunit and constrained the conformational dynamics of the heterodimer. Pranlukast decreased the clonogenicity of breast cancer cells on mammosphere formation assay but had no impact on the viability of bulk tumor cells. Brief exposure of MDA-MB-231 cells to pranlukast altered CD49f-dependent signaling, reducing focal adhesion kinase (FAK) and phosphatidylinositol 3-kinase (PI3K) activation. Further, pranlukast-treated cells showed decreased CD44 and SOX2 expression, SOX2 promoter transactivation, and in vivo tumorigenicity, supporting that this drug reduces the frequency of CSC.

Conclusion

Our results support the function of pranlukast as a CD49f antagonist that reduces the CSC population in triple-negative breast cancer cells. The pharmacokinetics and toxicology of this drug have already been established, rendering a potential adjuvant therapy for breast cancer patients.

Proximity Labeling Techniques to Study Chromatin

Mammals contain over 200 different cell types, yet nearly all have the same genomic DNA sequence. It is a key question in biology how the genetic instructions in DNA are selectively interpreted by cells to specify various transcriptional programs and therefore cellular identity. The structural and functional organization of chromatin governs the transcriptional state of individual genes. To understand how genomic loci adopt different levels of gene expression, it is critical to characterize all local chromatin factors as well as long-range interactions in the 3D nuclear compartment. Much of our current knowledge regarding protein interactions in a chromatin context is based on affinity purification of chromatin components coupled to mass spectrometry (AP-MS). AP-MS has been invaluable to map strong protein-protein interactions in the nucleus. However, the interaction is detected after cell lysis and biochemical enrichment, allowing for loss or gain of false positive or negative interaction partners. Recently, proximity-dependent labeling methods have emerged as powerful tools for studying chromatin in its native context. These methods take advantage of engineered enzymes that are fused to a chromatin factor of interest and can directly label all factors in proximity. Subsequent pull-down assays followed by mass spectrometry or sequencing approaches provide a comprehensive snapshot of the proximal chromatin interactome. By combining this method with dCas9, this approach can also be extended to study chromatin at specific genomic loci. Here, we review and compare current proximity-labeling approaches available for studying chromatin, with a particular focus on new emerging technologies that can provide important insights into the transcriptional and chromatin interaction networks essential for cellular identity.

The Prognostic and Predictive Value of SOX2+ Cell Densities in Patients Treated for Colorectal Cancer

SOX2 (sex-determining region-Y homeobox-2) is a transcription factor essential for the maintenance of pluripotency and is also associated with stem-cell-like properties in preclinical cancer models. Our previous study on a cohort of stage III colon cancer patients demonstrated high SOX2⁺ cell densities were associated with poor prognosis. However, most patients were treated with adjuvant chemotherapy so the prognostic value of SOX2 could not be assessed independently from its value as a predictive marker for non-response to chemotherapy. This study aimed to assess whether SOX2 was a true prognostic marker or a marker for chemotherapy response in a historical cohort of patients, a high proportion of whom were chemotherapy-naïve. SOX2 immunostaining was performed on tissue micro-arrays containing tumor cores from 797 patients with stage II and III colorectal cancer. SOX2⁺ cell densities were then quantified with StrataQuest digital image analysis software. Overall survival was assessed using Kaplan-Meier estimates and Cox regression. It was found that high SOX2⁺ cell densities were not associated with poor overall survival. Furthermore, all patients had a significant improvement in survival after 5-fluorouracil (5-FU) treatment, irrespective of their SOX2⁺ cell density. Therefore, SOX2⁺ cell densities were not associated with prognosis or chemotherapy benefit in this study. This is in contrast to our previous study, in which most patients received oxaliplatin as part of their treatment, in addition to 5-FU. This suggests SOX2 may predict response to oxaliplatin treatment, but not 5-FU.

A Sox2:miR-486-5p Axis Regulates Survival of GBM Cells by Inhibiting Tumor Suppressor Networks

Glioblastoma multiforme (GBM) and other solid malignancies are heterogeneous and contain subpopulations of tumor cells that exhibit stem-like features. Our recent findings point to a dedifferentiation mechanism by which reprogramming transcription factors Oct4 and Sox2 drive the stem-like phenotype in glioblastoma, in part, by differentially regulating subsets of miRNAs. Currently, the molecular mechanisms by which reprogramming transcription factors and miRNAs coordinate cancer stem cell tumor-propagating capacity are unclear. In this study, we identified miR-486-5p as a Sox2-induced miRNA that targets the tumor suppressor genes PTEN and FoxO1 and regulates the GBM stem-like cells. miR-486-5p associated with the GBM stem cell phenotype and Sox2 expression and was directly induced by Sox2 in glioma cell lines and patient-derived neurospheres. Forced expression of miR-486-5p enhanced the self-renewal capacity of GBM neurospheres, and inhibition of endogenous miR-486-5p activated PTEN and FoxO1 and induced cell death by upregulating proapoptotic protein BIM via a PTEN-dependent mechanism. Furthermore, delivery of miR-486-5p antagomirs to preestablished orthotopic GBM neurosphere-derived xenografts using advanced nanoparticle formulations reduced tumor sizes in vivo and enhanced the cytotoxic response to ionizing radiation. These results define a previously unrecognized and therapeutically targetable Sox2:miR-486-5p axis that enhances the survival of GBM stem cells by repressing tumor suppressor pathways. SIGNIFICANCE: This study identifies a novel axis that links core transcriptional drivers of cancer cell stemness to miR-486-5p-dependent modulation of tumor suppressor genes that feeds back to regulate glioma stem cell survival.

SOX2 has dual functions as a regulator in the progression of neuroendocrine prostate cancer

The mechanisms underlying the lineage switching from prostate adenocarcinoma (AdPC) to lethal neuroendocrine prostate cancer (NEPC) have yet to be completely elucidated. In this study, RNA sequencing data from a unique patient-derived xenograft NEPC model and a clinical NEPC cohort were used to identify the potential genes driving NEPC progression. Enrichr analysis resulted in the identification of SRY-related HMG-box gene 2 (SOX2) as a potential repressor that causes decrease in the expression of AdPC specific genes in NEPC. Assays involving the stable overexpression of SOX2 in LNCaP and CWR22RV1 cells validated this role of SOX2 in vitro. Mechanistic studies showed that the repressor role of SOX2 was attributed to the marked global hypomethylation of histone H3, which was driven by the activation of lysine-specific demethylase 1 (LSD1). Furthermore, Enrichr also predicted SOX2 as a driver gene involved in the upregulation of NEPC specific genes. However, SOX2 alone could only marginally induce the expression of some neuroendocrine markers in vitro, which was consistent with previous reports. Moreover, we also elucidated the molecular features of LNCaP-SOX2 cells that may confer resistance to androgen-deprivation therapy (ADT) and the inclination toward neuroendocrine transdifferentiation. The results of this study reveal a novel mechanism for SOX2 in the progression of NEPC via LSD1-mediated global epigenetic modulation. This discovery suggests that LSD1 may be a selective target for the prevention of NEPC progression.

SOX9: The master regulator of cell fate in breast cancer

SRY-related high-mobility group box 9 (SOX9) is an indispensable transcription factor that regulates multiple developmental pathways related to stemness, differentiation, and progenitor development. Previous studies have demonstrated that the SOX9 protein directs pathways involved in tumor initiation, proliferation, migration, chemoresistance, and stem cell maintenance, thereby regulating tumorigenesis as an oncogene. SOX9 overexpression is a frequent event in breast cancer (BC) subtypes. Of note, the molecular mechanisms and functional regulation underlying SOX9 upregulation during BC progression are still being uncovered. The focus of this review is to appraise recent advances regarding the involvement of SOX9 in BC pathogenesis. First, we provide a general overview of SOX9 structure and function, as well as its involvement in various kinds of cancer. Next, we discuss pathways of SOX9 regulation, particularly its miRNA-mediated regulation, in BC. Finally, we describe the involvement of SOX9 in BC pathogenesis via its regulation of pathways involved in regulating cancer hallmarks, as well as its clinical and therapeutic importance. In general, this review article aims to serve as an ample source of knowledge on the involvement of SOX9 in BC progression. Targeting SOX9 activity may improve therapeutic strategies to treat BC, but precisely inhibiting SOX9 using drugs and/or small peptides remains a huge challenge for forthcoming cancer research.

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.

SOX2 and BCL-2 Expressions in Odontogenic Keratocyst and Ameloblastoma

Background

The purpose of this experimental study was to compare the immunohistochemical expression of SOX2 and BCL-2 in Odontogenic Keratocyst (OKC) and Ameloblastoma (AB) specimens, and to identify a possible correlation in their expression.

Material and Methods

Immunohistochemical analysis was performed to evaluate SOX2 and BCL-2 expression in OKC (n = 20) and AB (n = 20). The immunoexpression was analyzed by a quantitative and qualitative scoring system. The comparison between the immunoexpression of SOX 2 and BCL-2 was assessed by the Mann-Whitney U-test. Spearman’s correlation coefficient evaluated the correlation between SOX2 and BCL-2 expressions.

Results

SOX2 and BCL-2 expression was observed in all specimens of OKC in the full thickness of the epithelium lining. SOX2 immunostaining was higher in OKC, in comparison with AB samples (P<0.05). BCL-2 immunostaining between OKC and AB was not statistically significant. There was no significant correlation between SOX2 and BCL-2 in OKC and AB specimens.

Conclusions

SOX2 and BCL-2 expressions in OKC may suggest their relationship with the biological behavior of this lesion, and the higher expression of SOX2 might be an upstream influence on the Hh signaling pathway.

Key words:Odontogenic keratocyst; Ameloblastoma; Odontogenic tumor; SOX2; BCL-2.

SOX2 Represses Hepatitis B Virus Replication by Binding to the Viral EnhII/Cp and Inhibiting the Promoter Activation

Hepatitis B virus (HBV) replication is controlled by four promoters (preS1, preS2, Cp, and Xp) and two enhancers (EnhI and EnhII). EnhII stimulates Cp activity to regulate the transcriptions of precore, core, polymerase, and pregenomic RNAs, and therefore, EnhII/Cp is essential for the regulation of HBV replication. This study revealed a distinct mechanism underlying the suppression of EnhII/Cp activation and HBV replication. On the one hand, the sex determining region Y box2 (SOX2), a transcription factor, is induced by HBV. On the other hand, SOX2, in turn, represses the expression levels of HBV RNAs, HBV core-associated DNA, hepatitis B surface antigen (HBsAg), and hepatitis B e antigen (HBeAg), thereby playing an inhibitory role during HBV replication. Further studies indicated that SOX2 bound to the EnhII/Cp DNA and repressed the promoter activation. With the deletion of the high mobility group (HMG) domain, SOX2 loses the ability to repress EnhII/Cp activation, viral RNA transcription, HBV core-associated DNA replication, HBsAg and HBeAg production, as well as fails to enter the nucleus, demonstrating that the HMG domain is required for the SOX2-mediated repression of HBV replication. Moreover, SOX2 represses HBsAg and HBeAg secretion in BALB/c mice sera, and attenuates HBV 3.5 kb RNA transcription and hepatitis B virus core protein (HBc) production in the liver tissues, demonstrating that SOX2 suppresses HBV replication in mice. Furthermore, the results revealed that the HMG domain was required for SOX2-mediated repression of HBV replication in the mice. Taken together, the above facts indicate that SOX2 acts as a new host restriction factor to repress HBV replication by binding to the viral EnhII/Cp and inhibiting the promoter activation through the HMG domain.

Differential sequences and single nucleotide polymorphism of exosomal SOX2 DNA in cancer

Glioblastoma multiforme (GBM) is the most common form of brain cancer, with an average life expectancy of fewer than two years post-diagnosis. We have previously reported that cancer cell originated exosomes, including GBM, have NANOG and NANOGP8 DNA associated with them. The exosomal NANOG DNA has certain differences as compared to its normal counterpart that are of immense importance as a potential cancer biomarker. NANOG has been demonstrated to play an essential role in the maintenance of embryonic stem cells, and its pseudogene, NANOGP8, is suggested to promote the cancer stem cell phenotype. Similarly, SOX2 is another stemness gene highly expressed in cancer stem cells with an intimate involvement in GBM progression and metastasis as well as promotion of tumorigenicity in Neuroblastoma (NB). Since exosomes are critical in intercellular communication with a role in dissipating hallmark biomolecules responsible for cancer, we conducted a detailed analysis of the association of the SOX2 gene with exosomes whose sequence modulations with further research and appropriate sample size can help to identify diagnostic markers for cancer. We have detected SOX2 DNA associated with exosomes and have identified some of the SNPs and nucleotide variations in the sequences from a GBM and SH-SY5Y sample. Although a further systematic investigation of exosomal DNA from GBM and NB patient's blood is needed, finding of SOX2 DNA in exosomes in the current study may have value in clinical research. SOX2 is known to be misregulated in cancer cells by changes in miRNA function, such as SNPs in the binding sites. Our finding of cancer-specific SNPs in exosomal SOX2 DNA sequence may reflect those changes in the cancer stem cells as well as cancer cells. A series of our study on embryonic stem cell gene analysis in exosomal DNA may lead to a minimally invasive exosome-based diagnosis, and give us a key in understanding the mechanisms of cancer formation, progression, and metastasis.

Blood-Based SOX2-Promoter Methylation in Relation to Exercise and PM2.5 Exposure among Taiwanese Adults

Increased ventilation during exercise in polluted areas could trigger airway inflammation. We evaluated blood DNA methylation of the SOX2-promoter region in relation to exercise and PM_2.5 in Taiwanese adults. Data of 948 participants aged 30–70 years were retrieved from the Taiwan Biobank Database (2008–2015) and the Air Quality Monitoring Database (2006–2011). PM_2.5 was positively associated with SOX2-promoter methylation (β = 0.000216; p < 0.0001). The interaction between PM_2.5 and exercise on SOX2-promoter methylation was significant (p = 0.0146). After stratification by exercise habits, PM_2.5 was positively associated with SOX2 methylation in only individuals who did regular exercise (β = 0.0003490; p < 0.0001). After stratification by exercise habits and residential areas, SOX2-promoter methylation levels in those who lived in the southern area were higher for both the regular exercise (β = 0.00272; p = 0.0172) and no regular exercise groups (β = 0.002610 and p = 0.0162). SOX2-promoter methylation levels in those who lived in the northern area and did regular exercise were lower; β = -0.00314 (p = 0.0036). In conclusion, PM_2.5 was positively associated with SOX2-promoter methylation in participants who did regular exercise. Living in the southern area was positively associated with SOX2-promoter methylation regardless of exercise habits.

A SOX2 Reporter System Identifies Gastric Cancer Stem-Like Cells Sensitive to Monensin

Gastric cancer remains a serious health burden with few therapeutic options. Therefore, the recognition of cancer stem cells (CSCs) as seeds of the tumorigenic process makes them a prime therapeutic target. Knowing that the transcription factors SOX2 and OCT4 promote stemness, our approach was to isolate stem-like cells in human gastric cancer cell lines using a traceable reporter system based on SOX2/OCT4 activity (SORE6-GFP). Cells transduced with the SORE6-GFP reporter system were sorted into SORE6+ and SORE6- cell populations, and their biological behavior characterized. SORE6+ cells were enriched for SOX2 and exhibited CSC features, including a greater ability to proliferate and form gastrospheres in non-adherent conditions, a larger in vivo tumor initiating capability, and increased resistance to 5-fluorouracil (5-FU) treatment. The overexpression and knockdown of SOX2 revealed a crucial role of SOX2 in cell proliferation and drug resistance. By combining the reporter system with a high-throughput screening of pharmacologically active small molecules we identified monensin, an ionophore antibiotic, displaying selective toxicity to SORE6+ cells. The ability of SORE6-GFP reporter system to recognize cancer stem-like cells facilitates our understanding of gastric CSC biology and serves as a platform for the identification of powerful therapeutics for targeting gastric CSCs.

SOX2 protein transduction directly converts human fibroblasts into oligodendrocyte-like cells

Oligodendrocyte precursor cells (OPCs) are ideal therapeutic cells for treatment of spinal cord injuries and diseases that affect myelin. However, it is necessary to generate a cell population with a low risk of teratoma formation and oncogenesis from a patient's somatic cells. In this study, we investigated the direct reprogramming of fibroblasts to oligodendrocyte-like cells in one step with a safe non-genetic delivery method that used protein transduction. Cell morphology and the lineage-specific marker expression profile indicated that human foreskin fibroblasts (HFFs) were converted into oligodendrocyte-like cells by the application of pluripotency factors and the use of a permissible induction medium. Our data demonstrated that SOX2 was sufficient to directly drive OPC fate conversion from HFF by a genetic-free approach. Therefore, this work has provided a strategy to OPC reprogramming by a non-integrating approach for future use in disease modeling and may ultimately provide applications for patient-specific cell-based regenerative medicine.

Detection of tumor antigens and tumor-antigen specific T cells in NSCLC patients: Correlation of the quality of T cell responses with NSCLC subtype

Allogeneic cancer cell lines serve as universal source of tumor-associated antigens in cancer vaccines. Immunogenic high hydrostatic pressure-killed cancer cells derived from cell lines can be used for the generation of dendritic cell (DC)-based active cellular immunotherapy of non-small cell lung cancer (NSCLC). We investigated the expression of 12 known NSCLC tumor-associated antigens (TAA) (CEA, MAGE-A1, MAGE-A3, MAGE-A4, PRAME, hTERT, HER2, MUC1, Survivin, STEAP1, SOX2 and NY-ESO-1) in 6 NSCLC cell lines as candidates for the generation of DC-based lung cancer vaccine. We showed that the selected antigenic profile of these cell lines overlaps to various degrees with that of primary NSCLC tumors (n = 52), indicating that 4 out of 6 NSCLC cell lines would be suitable for DC-based vaccine generation. We further investigated the presence of TAA-specific T cells in blood of NSCLC patients (n = 32) using commercially available peptide mixes in an in vitro stimulation assay. IFN-γ⁺CD8⁺ and IFN-γ⁺CD4⁺ T cell responses to all antigens were detected in NSCLC patients. Interestingly, despite higher TAA expression in squamous cell carcinoma (SCC) the responsiveness of patients' T cells to stimulation was significantly lower in SCC patients than in adenocarcinoma (AC) patients. This suggests qualitative differences in T cell functionality between NSCLC subtypes. Based on this study, and in order to maximize the amount of treatable patients, we selected a mix of H520 and H522 NSCLC cell lines for DC-based vaccine preparation. We also established a minimal panel of antigenic peptide mixes (CEA, hTERT, PRAME, HER2) for immunomonitoring of T cell responses during the DC-based lung cancer immunotherapy in Phase I lung cancer clinical trial (NCT02470468).