Y-box binding protein-1 induces the expression of CD44 and CD49f leading to enhanced self-renewal, mammosphere growth, and drug resistance

Mechanism of Endogenous Peptide PDYBX1 and Precursor Protein YBX1 in Hirschsprung's Disease

Endogenous peptides, bioactive agents with a small molecular weight and outstanding absorbability, regulate various cellular processes and diseases. However, their role in the occurrence of Hirschsprung's disease (HSCR) remains unclear. Here, we found that the expression of an endogenous peptide derived from YBX1 (termed PDYBX1 in this study) was upregulated in the aganglionic colonic tissue of HSCR patients, whereas its precursor protein YBX1 was downregulated. As shown by Transwell and cytoskeleton staining assays, silencing YBX1 inhibited the migration of enteric neural cells, and this effect was partially reversed after treatment with PDYBX1. Moreover, immunoprecipitation and immunofluorescence revealed that ERK2 bound to YBX1 and PDYBX1. Downregulation of YBX1 blocked the ERK1/2 pathway, but upregulation of PDYBX1 counteracted this effect by binding to ERK2, thereby promoting cell migration and proliferation. Taken together, the endogenous peptide PDYBX1 may partially alleviate the inhibition of the ERK1/2 pathway caused by the downregulation of its precursor protein YBX1 to antagonize the impairment of enteric neural cells. PDYBX1 may be exploited to design a novel potential therapeutic agent for HSCR.

Inhibition of protein translational machinery in triple-negative breast cancer as a promising therapeutic strategy

Y-box binding protein-1 (YB-1) is a proto-oncogenic protein associated with protein translation regulation. It plays a crucial role in the development and progression of triple-negative breast cancer (TNBC). In this study, we describe a promising approach to inhibit YB-1 using SU056, a small-molecule inhibitor. SU056 physically interacts with YB-1 and reduces its expression, which helps to restrain the progression of TNBC. Proteome profiling analysis indicates that the inhibition of YB-1 by SU056 can alter the proteins that regulate protein translation, an essential process for cancer cell growth. Preclinical studies on human cells, mice, and patient-derived xenograft tumor models show the effectiveness of SU056. Moreover, toxicological studies have shown that SU056 treatment and dosing are well tolerated without any adverse effects. Overall, our study provides a strong foundation for the further development of SU056 as a potential treatment option for patients with TNBC by targeting YB-1.

Y-Box Binding Protein 1: Unraveling the Multifaceted Role in Cancer Development and Therapeutic Potential

Y-box binding protein 1 (YBX1), a member of the Cold Shock Domain protein family, is overexpressed in various human cancers and is recognized as an oncogenic gene associated with poor prognosis. YBX1's functional diversity arises from its capacity to interact with a broad range of DNA and RNA molecules, implicating its involvement in diverse cellular processes. Independent investigations have unveiled specific facets of YBX1's contribution to cancer development. This comprehensive review elucidates YBX1's multifaceted role in cancer across cancer hallmarks, both in cancer cell itself and the tumor microenvironment. Based on this, we proposed YBX1 as a potential target for cancer treatment. Notably, ongoing clinical trials addressing YBX1 as a target in breast cancer and lung cancer have showcased its promise for cancer therapy. The ramp up in in vitro research on targeting YBX1 compounds also underscores its growing appeal. Moreover, the emerging role of YBX1 as a neural input is also proposed where the high level of YBX1 was strongly associated with nerve cancer and neurodegenerative diseases. This review also summarized the up-to-date advanced research on the involvement of YBX1 in pancreatic cancer.

Upregulated PARP1 confers breast cancer resistance to CDK4/6 inhibitors via YB-1 phosphorylation

BACKGROUND

Cyclic-dependent kinase (CDK) 4/6 kinases, as the critical drivers of the cell cycle, are involved in the tumor progression of various malignancies. Pharmacologic inhibitors of CDK4/6 have shown significant clinical prospects in treating hormone receptor-positive and human epidermal growth factor receptor-negative (HR + /HER2-) breast cancer (BC) patients. However, acquired resistance to CDK4/6 inhibitors (CDK4/6i), as a common issue, has developed rapidly. It is of great significance that the identification of novel therapeutic targets facilitates overcoming the CDK4/6i resistance. PARP1, an amplified gene for CDK4/6i-resistant patients, was found to be significantly upregulated during the construction of CDK4/6i-resistant strains. Whether PARP1 drives CDK4/6i resistance in breast cancer is worth further study.

METHOD

PARP1 and p-YB-1 protein levels in breast cancer cells and tissues were quantified using Western blot (WB) analysis, immunohistochemical staining (IHC) and immunofluorescence (IF) assays. Bioinformatics analyses of Gene Expression Profiling Interactive Analysis (GEPIA), Genomics of Drug Sensitivity in Cancer (GDSC) and Cancer Cell Line Encyclopedia (CCLE) datasets were applied to explore the relationship between YB-1/PARP1 protein levels and CDK4/6i IC50. Cell Counting Kit-8 (CCK-8) and crystal violet staining assays were performed to evaluate cell proliferation rates and drug killing effects. Flow cytometry assays were conducted to assess apoptosis rates and the G1/S ratio in the cell cycle. An EdU proliferation assay was used to detect the DNA replication ratio after treatment with PARP1 and YB-1 inhibitors. A ChIP assay was performed to assess the interaction of the transcription factor YB-1 and associated DNA regions. A double fluorescein reporter gene assay was designed to assess the influence of WT/S102A/S102E YB-1 on the promoter region of PARP1. Subcutaneous implantation models were applied for in vivo tumor growth evaluations.

RESULTS

Here, we reported that PARP1 was amplified in breast cancer cells and CDK4/6i-resistant patients, and knockdown or inhibition of PARP1 reversed drug resistance in cell experiments and animal models. In addition, upregulation of transcription factor YB-1 also occurred in CDK4/6i-resistant breast cancer, and YB-1 inhibition can regulate PARP1 expression. p-YB-1 and PARP1 were upregulated when treated with CDK4/6i based on the WB and IF results, and elevated PARP1 and p-YB-1 were almost simultaneously observed during the construction of MCF7AR-resistant strains. Inhibition of YB-1 or PAPR1 can cause decreased DNA replication, G1/S cycle arrest, and increased apoptosis. We initially confirmed that YB-1 can bind to the promoter region of PARP1 through a ChIP assay. Furthermore, we found that YB-1 phosphorylated at S102 was crucial for PARP1 transcription according to the double fluorescein reporter gene assay. The combination therapy of YB-1 inhibitors and CDK4/6i exerted a synergistic antitumor effect in vitro and in vivo. The clinical data suggested that HR + /HER2- patients with low expression of p-YB-1/PARP1 may be sensitive to CDK4/6i in breast cancer.

CONCLUSION

These findings indicated that a ''YB-1/PARP1'' loop conferred resistance to CDK4/6 inhibitors. Furthermore, interrupting the loop can enhance tumor killing in the xenograft tumor model, which provides a promising strategy against drug resistance in breast cancer.

Circular RNA cFAM210A, degradable by HBx, inhibits HCC tumorigenesis by suppressing YBX1 transactivation

Hepatitis B protein x (HBx) has been reported to promote tumorigenesis in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC), but the mechanism awaits further investigation. In this study, we found that cFAM210A (a circular RNA derived from the third exon of transcript NM_001098801 of the FAM210A gene; CircBase ID: hsa_circ_0003979) can be silenced by HBx. cFAM210A expression was downregulated and negatively correlated with tumorigenesis in patients with HBV-related HCC. Furthermore, cFAM210A reduced the proliferation, stemness, and tumorigenicity of HCC cells. Mechanistically, HBx increased the N6-methyladenosine (m6A) level of cFAM210A by promoting the expression of RBM15 (an m6A methyltransferase), thus inducing the degradation of cFAM210A via the YTHDF2-HRSP12-RNase P/MRP pathway. cFAM210A bound to YBX1 and inhibited its phosphorylation, suppressing its transactivation function toward MET. These findings suggest the important role of circular RNAs in HBx-induced hepatocarcinogenesis and identify cFAM210A a potential target in the prevention and treatment of HBV-related HCC.

YBX1 as an oncogenic factor in T-cell acute lymphoblastic leukemia

Y-box-binding protein 1 (YBX1), a member of the RNA-binding protein family, is a critical regulator of cell survival in various solid tumors and acute myeloid leukemia. However, the function of YBX1 in T-cell acute lymphoblastic leukemia (T-ALL) remains elusive. Here, we found that YBX1 was upregulated in patients with T-ALL, T-ALL cell lines, and NOTCH1-induced T-ALL mice. Furthermore, depletion of YBX1 dramatically reduced cell proliferation, induced cell apoptosis, and induced G0/G1 phase arrest in vitro. Moreover, YBX1 depletion significantly decreased the leukemia burden in the human T-ALL xenograft and NOTCH1-induced T-ALL mice model in vivo. Mechanistically, downregulation of YBX1 markedly inhibited the expression of total AKT serine/threonine kinase (AKT), p-AKT, total extracellular signal-regulated kinase (ERK), and p-ERK in T-ALL cells. Taken together, our results uncovered a critical role of YBX1 in the leukemogenesis of T-ALL, which may have great potential as a biomarker and therapeutic target in T-ALL.

Differential contractility regulates cancer stem cell migration

Cancer stem cells (CSCs) are known to have a high capacity for tumor initiation and the formation of metastases. We have previously shown that in collagen constructs mimetic of aligned extracellular matrix architectures observed in carcinomas, breast CSCs demonstrate enhanced directional and total motility compared with more differentiated carcinoma populations. Here, we show that CSCs maintain increased motility in diverse environments including on 2D elastic polyacrylamide gels of various stiffness, 3D randomly oriented collagen matrices, and ectopic cerebral slices representative of a common metastatic site. A consistent twofold increase of CSC motility across platforms suggests a general shift in cell migration mechanics between well-differentiated carcinoma cells and their stem-like counterparts. To further elucidate the source of differences in migration, we demonstrate that CSCs are less contractile than the whole population (WP) and develop fewer and smaller focal adhesions and show that enhanced CSC migration can be tuned via contractile forces. The WP can be shifted to a CSC-like migratory phenotype using partial myosin II inhibition. Inversely, CSCs can be shifted to a less migratory WP-like phenotype using microtubule-destabilizing drugs that increase contractility or by directly enhancing contractile forces. This work begins to reveal the mechanistic differences driving CSC migration and raises important implications regarding the potentially disparate effects of microtubule-targeting agents on the motility of different cell populations.

YB-1 is a positive regulator of KLF5 transcription factor in basal-like breast cancer

Y-box binding protein 1 (YB-1) is a well-known oncogene highly expressed in various cancers, including basal-like breast cancer (BLBC). Beyond its role as a transcription factor, YB-1 is newly defined as an epigenetic regulator involving RNA 5-methylcytosine. However, its specific targets and pro-cancer functions are poorly defined. Here, based on clinical database, we demonstrate a positive correlation between Kruppel-like factor 5 (KLF5) and YB-1 expression in breast cancer patients, but a negative correlation with that of Dachshund homolog 1 (DACH1). Mechanistically, YB-1 enhances KLF5 expression not only through transcriptional activation that can be inhibited by DACH1, but also by stabilizing KLF5 mRNA in a RNA 5-methylcytosine modification-dependent manner. Additionally, ribosomal S6 kinase 2 (RSK2) mediated YB-1 phosphorylation at Ser102 promotes YB-1/KLF5 transcriptional complex formation, which co-regulates the expression of BLBC specific genes, Keratin 16 (KRT16) and lymphocyte antigen 6 family member D (Ly6D), to promote cancer cell proliferation. The RSK inhibitor, LJH685, suppressed BLBC cell tumourigenesis in vivo by disturbing YB-1-KLF5 axis. Our data suggest that YB-1 positively regulates KLF5 at multiple levels to promote BLBC progression. The novel RSK2-YB-1-KLF5-KRT16/Ly6D axis provides candidate diagnostic markers and therapeutic targets for BLBC.

YB-1 as an Oncoprotein: Functions, Regulation, Post-Translational Modifications, and Targeted Therapy

Y box binding protein 1 (YB-1) is a protein with a highly conserved cold shock domain (CSD) that also belongs to the family of DNA- and RNA-binding proteins. YB-1 is present in both the nucleus and cytoplasm and plays versatile roles in gene transcription, RNA splicing, DNA damage repair, cell cycle progression, and immunity. Cumulative evidence suggests that YB-1 promotes the progression of multiple tumor types and serves as a potential tumor biomarker and therapeutic target. This review comprehensively summarizes the emerging functions, mechanisms, and regulation of YB-1 in cancers, and further discusses targeted strategies.

Role of YB-1 Protein in Inflammation

This review discusses the role of the multifunctional DNA/RNA-binding protein YB-1 in inflammation. YB-1 performs multiple functions in the cell depending on its location: it acts as transcriptional factor for many genes in the nucleus, regulates translation and stability of mRNA in the cytoplasm, and becomes a paracrine factor when secreted from the cells. The review presents the data on the YB-1-mediated regulation of inflammation-associated genes, as well as results of studies on the YB-1 role in animal model of various inflammatory diseases, such as glomerulonephritis, tubulointerstitial fibrosis, and bacterial sepsis, and on the YB-1 expression in different human diseases associated with inflammatory processes in kidney, liver, and endometrium. The last section of the review presents several approaches to the regulation of YB-1 with small molecules in the treatment of inflammatory diseases.

lncRNA BORG:TRIM28 Complexes Drive Metastatic Progression by Inducing α6 Integrin/CD49f Expression in Breast Cancer Stem Cells

Triple-negative breast cancer (TNBC) is the most lethal subtype of breast cancer, with its aggressive phenotype being attributed to chemotherapy resistance, metastatic dissemination, and rapid disease recurrence. Breast cancer stem cells (BCSC) are significant contributors to tumor initiation, as well as to the acquisition of aggressive tumorigenic phenotypes, namely due to their ability to self-replicate and to produce heterogeneous differentiated tumor cells. To elucidate the underlying mechanisms that drive BCSC tumorigenicity in TNBC, we identified the long noncoding RNA (lncRNA) B MP/ O P- R esponsive G ene (BORG) as an enhancer of BCSC phenotypes. Indeed, we found BORG expression to: (i) correlate with stem cell markers Nanog, Aldh1a3, and Itga6 (α6 integrin/CD49f); (ii) enhance stem cell phenotypes in murine and human TNBC cells, and (iii) promote TNBC tumor initiation in mice. Mechanistically, BORG promoted BCSC phenotypes through its ability to interact physically with the E3 SUMO ligase TRIM28. Moreover, TRIM28 binding was observed in the promoter region of Itga6, whose genetic inactivation prevented BORG:TRIM28 complexes from: (i) inducing BCSC self-renewal and expansion in vitro, and (ii) eliciting BCSC metastatic outgrowth in the lungs of mice. Collectively, these findings implicate BORG:TRIM28 complexes as novel drivers of BCSC phenotypes in developing and progressing TNBCs. IMPLICATIONS: This work establishes the lncRNA BORG as a driver of BCSC phenotypes and the aggressive behaviors of TNBCs, events critically dependent upon the formation of BORG:TRIM28 complexes and expression of α6 integrin.

A comprehensive review of the functions of YB-1 in cancer stemness, metastasis and drug resistance

The Y Box binding protein 1 (YB-1) is a member of the highly conserved Cold Shock Domain protein family with multifunctional properties both in the cytoplasm and inside the nucleus. YB-1 is also involved in various cellular functions, including regulation of transcription, mRNA stability, and splicing. Recent studies have associated YB-1 with the regulation of the malignant phenotypes in several tumor types. In this review article, we provide an in-depth and expansive review of the literature pertaining to the multiple physiological functions of YB-1. We will also review the role of YB-1 in cancer development, progression, metastasis, and drug resistance in various malignancies, with more weight on literature published in the last decade. The methodology included querying databases PubMed, Embase, and Google Scholar for Y box binding protein 1, YB-1, YBX1, and Y-box-1.

YB1 regulates miR-205/200b-ZEB1 axis by inhibiting microRNA maturation in hepatocellular carcinoma

BACKGROUND

Y-box binding protein 1 (YB1 or YBX1) plays a critical role in tumorigenesis and cancer progression. However, whether YB1 affects malignant transformation by modulating non-coding RNAs remains largely unknown. This study aimed to investigate the relationship between YB1 and microRNAs and reveal the underlying mechanism by which YB1 impacts on tumor malignancy via miRNAs-mediated regulatory network.

METHODS

The biological functions of YB1 in hepatocellular carcinoma (HCC) cells were investigated by cell proliferation, wound healing, and transwell invasion assays. The miRNAs dysregulated by YB1 were screened by microarray analysis in HCC cell lines. The regulation of YB1 on miR-205 and miR-200b was determined by quantitative real-time PCR, dual-luciferase reporter assay, RNA immunoprecipitation, and pull-down assay. The relationships of YB1, DGCR8, Dicer, TUT4, and TUT1 were identified by pull-down and coimmunoprecipitation experiments. The cellular co-localization of YB1, DGCR8, and Dicer were detected by immunofluorescent staining. The in vivo effect of YB1 on tumor metastasis was determined by injecting MHCC97H cells transduced with YB1 shRNA or shControl via the tail vein in nude BALB/c mice. The expression levels of epithelial to mesenchymal transition markers were detected by immunoblotting and immunohistochemistry assays.

RESULTS

YB1 promoted HCC cell migration and tumor metastasis by regulating miR-205/200b-ZEB1 axis partially in a Snail-independent manner. YB1 suppressed miR-205 and miR-200b maturation by interacting with the microprocessors DGCR8 and Dicer as well as TUT4 and TUT1 via the conserved cold shock domain. Subsequently, the downregulation of miR-205 and miR-200b enhanced ZEB1 expression, thus leading to increased cell migration and invasion. Furthermore, statistical analyses on gene expression data from HCC and normal liver tissues showed that YB1 expression was positively associated with ZEB1 expression and remarkably correlated with clinical prognosis.

CONCLUSION

This study reveals a previously undescribed mechanism by which YB1 promotes cancer progression by regulating the miR-205/200b-ZEB1 axis in HCC cells. Furthermore, these results highlight that YB1 may play biological functions via miRNAs-mediated gene regulation, and it can serve as a potential therapeutic target in human cancers.

Targeting the Y-box Binding Protein-1 Axis to Overcome Radiochemotherapy Resistance in Solid Tumors

Multifunctional Y-box binding protein-1 (YB-1) is highly expressed in different human solid tumors and is involved in various cellular processes. DNA damage is the major mechanism by which radiochemotherapy (RCT) induces cell death. On induction of DNA damage, a multicomponent signal transduction network, known as the DNA damage response, is activated to induce cell cycle arrest and initiate DNA repair, which protects cells against damage. YB-1 regulates nearly all cancer hallmarks described to date by participating in DNA damage response, gene transcription, mRNA splicing, translation, and tumor stemness. YB-1 lacks kinase activity, and p90 ribosomal S6 kinase and AKT are the key kinases within the RAS/mitogen-activated protein kinase and phosphoinositide 3-kinase pathways that directly activate YB-1. Thus, the molecular targeting of ribosomal S6 kinase and AKT is thought to be the most effective strategy for blocking the cellular function of YB-1 in human solid tumors. In this review, after describing the prosurvival effect of YB-1 with a focus on DNA damage repair and cancer cell stemness, clinical evidence will be provided indicating an inverse correlation between YB-1 expression and the treatment outcome of solid tumors after RCT. In the interest of being concise, YB-1 signaling cascades will be briefly discussed and the current literature on YB-1 posttranslational modifications will be summarized. Finally, the current status of targeting the YB-1 axis, especially in combination with RCT, will be highlighted.

MAP17 Expression in Colorectal Cancer Is a Prognostic Factor for Disease Recurrence and Dismal Prognosis Already in Early Stage Disease

BACKGROUND

Disease recurrence in colorectal cancer constitutes a major cause of significant cancer-associated morbidity and mortality. MAP17 is a small protein, and its overexpression in malignant tumors has been correlated with aggressive tumor phenotypes. The aim of the present study was to investigate the expression patterns of MAP17 in colorectal cancer specimens and to assess its clinical significance.

PATIENTS AND METHODS

Surgical specimens of 111 patients with primary resectable colorectal cancer constituted the study population. Expression of MAP17 was assessed by immunohistochemistry, and the results were correlated with clinical and survival data.

RESULTS

MAP17 was expressed in cancer cells and endothelial cells of tumor blood vessels. Expression of MAP17 more than 10% was correlated with advanced disease stage (p < 0.001), higher T classification (p = 0.007), the presence of lymph node metastasis (p < 0.001), vascular (p = 0.013) and perineural invasion (p = 0.012). Patients exhibiting MAP17 expression of more than 30% in cancer cells compared to those expressing MAP17 less than 10% demonstrated a significantly worse 3-year progression-free survival (35.2 vs. 91%, p < 0.001) and 5-year overall survival (40.8 vs. 91%, p < 0.001). Cox regression analysis confirmed MAP17 expression of more than 30% as a prognostic marker of progression free survival (HR 0.136, 95% CI = 0.056-0.329, p < 0.001) and overall survival (HR 0.144 [95% CI) = 0.049-0.419, p < 0.001) independent of other clinicopathological characteristics. Statistically significantly worse 3-year progression-free survival and 5-year overall survival was demonstrated in the subgroup analysis of patients with early stage cancer only and high expression of MAP17.

CONCLUSIONS

High MAP17 expression in patients with colorectal cancer is a significant risk factor for cancer-associated morbidity and mortality already in early stage disease.

Selective Anti-Cancer Effects of Plasma-Activated Medium and Its High Efficacy with Cisplatin on Hepatocellular Carcinoma with Cancer Stem Cell Characteristics

Hepatocellular carcinoma (HCC) is a major histological subtype of primary liver cancer. Ample evidence suggests that the pathological properties of HCC originate from hepatic cancer stem cells (CSCs), which are responsible for carcinogenesis, recurrence, and drug resistance. Cold atmospheric-pressure plasma (CAP) and plasma-activated medium (PAM) induce apoptosis in cancer cells and represent novel and powerful anti-cancer agents. This study aimed to determine the anti-cancer effect of CAP and PAM in HCC cell lines with CSC characteristics. We showed that the air-based CAP and PAM selectively induced cell death in Hep3B and Huh7 cells with CSC characteristics, but not in the normal liver cell line, MIHA. We observed both caspase-dependent and -independent cell death in the PAM-treated HCC cell lines. Moreover, we determined whether combinatorial PAM therapy with various anti-cancer agents have an additive effect on cell death in Huh7. We found that PAM highly increased the efficacy of the chemotherapeutic agent, cisplatin, while enhanced the anti-cancer effect of doxorubicin and the targeted-therapy drugs, trametinib and sorafenib to a lesser extent. These findings support the application of CAP and PAM as anti-cancer agents to induce selective cell death in cancers containing CSCs, suggesting that the combinatorial use of PAM and some specific anti-cancer agents is complemented mechanistically.

FOLFOX Therapy Induces Feedback Upregulation of CD44v6 through YB-1 to Maintain Stemness in Colon Initiating Cells

Cancer initiating cells (CICs) drive tumor formation and drug-resistance, but how they develop drug-resistance characteristics is not well understood. In this study, we demonstrate that chemotherapeutic agent FOLFOX, commonly used for drug-resistant/metastatic colorectal cancer (CRC) treatment, induces overexpression of CD44v6, MDR1, and oncogenic transcription/translation factor Y-box-binding protein-1 (YB-1). Our study revealed that CD44v6, a receptor for hyaluronan, increased the YB-1 expression through PGE2/EP1-mTOR pathway. Deleting CD44v6, and YB-1 by the CRISPR/Cas9 system attenuates the in vitro and in vivo tumor growth of CICs from FOLFOX resistant cells. The results of DNA:CD44v6 immunoprecipitated complexes by ChIP (chromatin-immunoprecipitation) assay showed that CD44v6 maintained the stemness traits by promoting several antiapoptotic and stemness genes, including cyclin-D1,BCL2,FZD1,GINS-1, and MMP9. Further, computer-based analysis of the clones obtained from the DNA:CD44v6 complex revealed the presence of various consensus binding sites for core stemness-associated transcription factors “CTOS” (c-Myc, TWIST1, OCT4, and SOX2). Simultaneous expressions of CD44v6 and CTOS in CD44v6 knockout CICs reverted differentiated CD44v6-knockout CICs into CICs. Finally, this study for the first time describes a positive feedback loop that couples YB-1 induction and CD44 alternative splicing to sustain the MDR1 and CD44v6 expressions, and CD44v6 is required for the reversion of differentiated tumor cells into CICs.

The transcriptional repressor BCL11A promotes breast cancer metastasis

The phenotypes of each breast cancer subtype are defined by their transcriptomes. However, the transcription factors that regulate differential patterns of gene expression that contribute to specific disease outcomes are not well understood. Here, using gene silencing and overexpression approaches, RNA-Seq, and splicing analysis, we report that the transcription factor B-cell leukemia/lymphoma 11A (BCL11A) is highly expressed in triple-negative breast cancer (TNBC) and drives metastatic disease. Moreover, BCL11A promotes cancer cell invasion by suppressing the expression of muscleblind-like splicing regulator 1 (MBNL1), a splicing regulator that suppresses metastasis. This ultimately increases the levels of an alternatively spliced isoform of integrin-α6 (ITGA6), which is associated with worse patient outcomes. These results suggest that BCL11A sustains TNBC cell invasion and metastatic growth by repressing MBNL1-directed splicing of ITGA6 Our findings also indicate that BCL11A lies at the interface of transcription and splicing and promotes aggressive TNBC phenotypes.

YB-1: The key to personalised prostate cancer management?

Y-box-binding protein 1 (YB-1) is a DNA/RNA binding protein increasingly implicated in the regulation of cancer cell biology. Normally located in the cytoplasm, nuclear localisation in prostate cancer is associated with more aggressive, potentially treatment-resistant disease. This is attributed to the ability of YB-1 to act as a transcription factor for various target genes associated with androgen receptor signalling, survival, DNA repair, proliferation, invasion, differentiation, angiogenesis and hypoxia. This review aims to examine the clinical potential of YB-1 in the detection and therapeutic management of prostate cancer.

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.

Polyphenols Extracted from Artemisia annua L. Exhibit Anti-Cancer Effects on Radio-Resistant MDA-MB-231 Human Breast Cancer Cells by Suppressing Stem Cell Phenotype, β-Catenin, and MMP-9

Artemisia annua L. has been reported to show anti-cancer activities. Here, we determined whether polyphenols extracted from Artemisia annua L. (pKAL) exhibit anti-cancer effects on radio-resistant MDA-MB-231 human breast cancer cells (RT-R-MDA-MB-231 cells), and further explored their molecular mechanisms. Cell viability assay and colony-forming assay revealed that pKAL inhibited cell proliferation on both parental and RT-R-MDA-MB-231 cells in a dose-dependent manner. The anti-proliferative effects of pKAL on RT-R-MDA-MB-231 cells were superior or similar to those on parental ones. Western blot analysis revealed that expressions of cluster of differentiation 44 (CD44) and Oct 3/4, matrix metalloproteinase-9 (MMP-9) and signal transducer and activator of transcription-3 (STAT-3) phosphorylation were significantly increased in RT-R-MDA-MB-231 cells compared to parental ones, suggesting that these proteins could be associated with RT resistance. pKAL inhibited the expression of CD44 and Oct 3/4 (CSC markers), and β-catenin and MMP-9 as well as STAT-3 phosphorylation of RT-R-MDA-MB-231. Regarding upstream signaling, the JNK or JAK2 inhibitor could inhibit STAT-3 activation in RT-R-MDA-MB-231 cells, but not augmented pKAL-induced anti-cancer effects. These findings suggest that c-Jun N-terminal kinase (JNK) or Janus kinase 2 (JAK2)/STAT3 signaling are not closely related to the anti-cancer effects of pKAL. In conclusion, this study suggests that pKAL exhibit anti-cancer effects on RT-R-MDA-MB-231 cells by suppressing CD44 and Oct 3/4, β-catenin and MMP-9, which appeared to be linked to RT resistance of RT-R-MDA-MB-231 cells.

Novel Aptamers Selected on Living Cells for Specific Recognition of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a high heterogeneous group of tumors with a distinctly aggressive nature and high rates of relapse. So far, the lack of any known targetable proteins has not allowed a specific anti-tumor treatment. Therefore, the identification of novel agents for specific TNBC targeting and treatment is desperately needed. Here, by integrating cell-SELEX (Systematic Evolution of Ligands by EXponential enrichment) for the specific recognition of TNBC cells with high-throughput sequencing technology, we identified a panel of 2′-fluoropyrimidine-RNA aptamers binding to TNBC cells and their cisplatin- and doxorubicin-resistant derivatives at low nanomolar affinity. These aptamers distinguish TNBC cells from both non-malignant and non-TNBC breast cancer cells and are able to differentiate TNBC histological specimens. Importantly, they inhibit TNBC cell capacity of growing in vitro as mammospheres, indicating they could also act as anti-tumor agents. Therefore, our newly identified aptamers are a valuable tool for selectively dealing with TNBC.

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Six 2′FPy-RNA aptamers were obtained by TNBC Cell-SELEX/NGS

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They distinguish TNBC cells from non-malignant and non-TNBC breast cancer cells

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They differentiate TNBC histological specimens by aptamer-based staining

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They inhibit TNBC cell lines capacity of growing in vitro as mammospheres

Molecular cloning and characterization of Y-box gene (Rpybx) from Manila clam and its expression analysis in different strains under low-temperature stress

Manila clam, Ruditapes philippinarum, is an economically important marine bivalve species. Y-box proteins are members of the cold shock proteins family and highly conserved from bacteria to humans. In this study, a novel Y-box gene (Rpybx) was cloned from the Manila clam and gene expression profiling was performed on three shell color strains (white, zebra and white zebra) and two wild populations (Southern and Northern) of R. philippinarum. The complete ORF length of Rpybx is 1367 bp, encoding 253 amino acids residues. Based on the amino acid sequence analysis and phylogenetic analysis, the Rpybx gene was identified as a member of the invertebrate Y-box proteins family. Rpybx has a similar tertiary structure to human Y-box protein YB-1. The Rpybx mRNA levels were analyzed by qPCR under acute and gradually varied cold stress. Under acute low-temperature stress, the expression of Rpybx mRNA in gills and hepatopancreas was significantly increased in all selected strains and populations (P < 0.05). The Northern population showed the lowest relative expression level of Rpybx. The expressions of Rpybx were greatly upregulated in gills and hepatopancreas of different stains and populations at 5 or -2°C under gradually varied temperature stress (P < 0.05). The results shed light on the biological function of the Rpybx gene in defending against low-temperature challenge and further exploring the molecular mechanism of cold tolerance and resistance in R. philippinarum.

YB-1 interplays with ERα to regulate the stemness and differentiation of ER-positive breast cancer stem cells

Background: Some stemness-associated transcription factors consistently play essential roles in the maintenance of pluripotency or induce the differentiation of cancer stem cells (CSCs). However, the regulatory mechanism of CSC stemness mediated by transcription factors has not been extensively explored. Here, we show that two transcription factors (YB-1 and ERα), which are simultaneously highly expressed in estrogen receptor (ER)-positive CSCs, interact with each other to regulate the stemness and differentiation of ER-positive CSCs. Methods: The expression of YB-1 was examined in ER-positive CSCs and patient specimens. Western blot, real-time PCR, cell viability analysis, tumorsphere formation assay and subcutaneous tumorigenesis assays were used to study the stemness functions of YB-1 and ERα in CSCs. The relationship between YB-1 and ERα in cells was studied by promoter activity analysis, the electrophoretic mobility shift assay (EMSA) and the Co-IP assay. The mechanisms and functional significance of YB-1 in the sensitivity of CSCs to tamoxifen were further investigated with both in vitro and in vivo models. Results: YB-1 was aberrantly upregulated in the cancerous tissue of ER-positive breast cancer patients and in CSCs. Knockdown of YB-1 in ER-positive CSCs significantly inhibited cell stemness and induced differentiation, and the expression of YB-1 could be regulated by estrogen signaling and ERα in ER-positive breast CSCs. The Co-IP results showed that YB-1 interacted directly with ERα specifically in ER-positive non-CSCs and that YB-1 induced ERα degradation by ubiquitination via direct interaction in differentiated cells. Cell differentiation induced by FBS could inhibit YB-1 phosphorylation and promote YB-1 protein transfer from the nucleus to the cytoplasm. Moreover, cell differentiation induced by targeting inhibited the expression of YB-1 in ER-positive CSCs, which increased the sensitivity of cells to tamoxifen in vitro and in vivo. Conclusion: The ERα/YB-1 axis has an important role in the regulation of ER-positive breast cancer stemness. The dephosphorylation of YB-1 and the interaction between YB-1 and ERα may be the switch that initiates the differentiation of ER-positive CSCs. Targeting YB-1 to sensitize ER-positive CSCs to antiestrogen therapy might represent a new therapeutic strategy that warrants further exploration.

Cold Atmospheric Plasma Restores Paclitaxel Sensitivity to Paclitaxel-Resistant Breast Cancer Cells by Reversing Expression of Resistance-Related Genes

Paclitaxel (Tx) is a widely used therapeutic chemical for breast cancer treatment; however, cancer recurrence remains an obstacle for improved prognosis of cancer patients. In this study, cold atmospheric plasma (CAP) was tested for its potential to overcome the drug resistance. After developing Tx-resistant MCF-7 (MCF-7/TxR) breast cancer cells, CAP was applied to the cells, and its effect on the recovery of drug sensitivity was assessed in both cellular and molecular aspects. Sensitivity to Tx in the MCF-7/TxR cells was restored up to 73% by CAP. A comparison of genome-wide expression profiles between the TxR cells and the CAP-treated cells identified 49 genes that commonly appeared with significant changes. Notably, 20 genes, such as KIF13B, GOLM1, and TLE4, showed opposite expression profiles. The protein expression levels of selected genes, DAGLA and CEACAM1, were recovered to those of their parental cells by CAP. Taken together, CAP inhibited the growth of MCF-7/TxR cancer cells and recovered Tx sensitivity by resetting the expression of multiple drug resistance–related genes. These findings may contribute to extending the application of CAP to the treatment of TxR cancer.

Co-targeting CK2α and YBX1 suppresses tumor progression by coordinated inhibition of the PI3K/AKT signaling pathway

Protein kinase CK2 alpha (CK2α) is involved in the development of multiple malignancies. Overexpression of Y-box binding protein 1 (YBX1) is related to tumor proliferation, drug resistance, and poor prognosis. Studies have demonstrated that both CK2 and YBX1 could regulate the PI3K/AKT pathway. In addition, we predicted that CK2 might be the upstream kinase of YBX1 through the Human Protein Reference Database (HPRD). Herein, we hypothesize that CK2 may interact with YBX1 and they regulate the PI3K/AKT signaling pathway together. Expressions of CK2α and YBX1 in cancer cell lines were evaluated by immunoblotting. The results showed that CK2α could regulate the expression of YBX1 at the transcriptional level, which is dependent on its enzymatic activity. Synergistic effects of PI3K/AKT pathway inactivation could be observed through combined inhibition of CK2α and YBX1, and YBX1 was required for CK2α-induced PI3K/AKT pathway activation. Further results demonstrated that CK2α could interact with YBX1 and PI3K/AKT antagonist decreased cell resistance to doxorubicin induced by co-activation of CK2α and YBX1. These results indicated that combined inhibition of CK2α and YBX1 showed synergistic effects in inactivating the PI3K/AKT signaling pathway and may be one of the mechanisms involved in tumor growth and migration.

Why Be One Protein When You Can Affect Many? The Multiple Roles of YB-1 in Lung Cancer and Mesothelioma

Lung cancers and malignant pleural mesothelioma (MPM) have some of the worst 5-year survival rates of all cancer types, primarily due to a lack of effective treatment options for most patients. Targeted therapies have shown some promise in thoracic cancers, although efficacy is limited only to patients harboring specific mutations or target expression. Although a number of actionable mutations have now been identified, a large population of thoracic cancer patients have no therapeutic options outside of first-line chemotherapy. It is therefore crucial to identify alternative targets that might lead to the development of new ways of treating patients diagnosed with these diseases. The multifunctional oncoprotein Y-box binding protein-1 (YB-1) could serve as one such target. Recent studies also link this protein to many inherent behaviors of thoracic cancer cells such as proliferation, invasion, metastasis and involvement in cancer stem-like cells. Here, we review the regulation of YB-1 at the transcriptional, translational, post-translational and sub-cellular levels in thoracic cancer and discuss its potential use as a biomarker and therapeutic target.

Benchmarking to the Gold Standard: Hyaluronan-Oxime Hydrogels Recapitulate Xenograft Models with In Vitro Breast Cancer Spheroid Culture

Many 3D in vitro models induce breast cancer spheroid formation; however, this alone does not recapitulate the complex in vivo phenotype. To effectively screen therapeutics, it is urgently needed to validate in vitro cancer spheroid models against the gold standard of xenografts. A new oxime-crosslinked hyaluronan (HA) hydrogel is designed, manipulating gelation rate and mechanical properties to grow breast cancer spheroids in 3D. This HA-oxime breast cancer model maintains the gene expression profile most similar to that of tumor xenografts based on a pan-cancer gene expression profile (comprising 730 genes) of three different human breast cancer subtypes compared to Matrigel or conventional 2D culture. Differences in gene expression between breast cancer cultures in HA-oxime versus Matrigel or 2D are confirmed for 12 canonical pathways by gene set variation analysis. Importantly, drug response is dependent on the culture method. Breast cancer cells respond better to the Rac inhibitor (EHT-1864) and the PI3K inhibitor (AZD6482) when cultured in HA-oxime versus Matrigel. This study demonstrates the superiority of an HA-based hydrogel as a platform for in vitro breast cancer culture of both primary, patient-derived cells and cell lines, and provides a hydrogel culture model that closely matches that in vivo.

Altered transcriptional regulatory proteins in glioblastoma and YBX1 as a potential regulator of tumor invasion

We have studied differentially regulated nuclear proteome of the clinical tissue specimens of glioblastoma (GBM, WHO Grade IV) and lower grades of gliomas (Grade II and III) using high resolution mass spectrometry- based quantitative proteomics approach. The results showed altered expression of many regulatory proteins from the nucleus such as DNA binding proteins, transcription and post transcriptional processing factors and also included enrichment of nuclear proteins that are targets of granzyme signaling – an immune surveillance pathway. Protein - protein interaction network analysis using integrated proteomics and transcriptomics data of transcription factors and proteins for cell invasion process (drawn from another GBM dataset) revealed YBX1, a ubiquitous RNA and DNA-binding protein and a transcription factor, as a key interactor of major cell invasion-associated proteins from GBM. To verify the regulatory link between them, the co-expression of YBX1 and six of the interacting proteins (EGFR, MAPK1, CD44, SOX2, TNC and MMP13) involved in cell invasion network was examined by immunohistochemistry on tissue micro arrays. Our analysis suggests YBX1 as a potential regulator of these key molecules involved in tumor invasion and thus as a promising target for development of new therapeutic strategies for GBM.

Crystal structure of a Y-box binding protein 1 (YB-1)-RNA complex reveals key features and residues interacting with RNA

The Y-box binding protein 1 (YB-1) is a member of the cold shock domain (CSD) protein family and is recognized as an oncogenic factor in several solid tumors. By binding to RNA, YB-1 participates in several steps of posttranscriptional regulation of gene expression, including mRNA splicing, stability, and translation; microRNA processing; and stress granule assembly. However, the mechanisms in YB-1-mediated regulation of RNAs are unclear. Previously, we used both systematic evolution of ligands by exponential enrichment (SELEX) and individual-nucleotide resolution UV cross-linking and immunoprecipitation coupled RNA-Seq (iCLIP-Seq) analyses, which defined the RNA-binding consensus sequence of YB-1 as CA(U/C)C. We also reported that through binding to its core motif CAUC in primary transcripts, YB-1 regulates the alternative splicing of a CD44 variable exon and the biogenesis of miR-29b-2 during both Drosha and Dicer steps. To elucidate the molecular basis of the YB-1-RNA interactions, we report high-resolution crystal structures of the YB-1 CSD in complex with different RNA oligos at 1.7 Å resolution. The structure revealed that CSD interacts with RNA mainly through π-π stacking interactions assembled by four highly conserved aromatic residues. Interestingly, YB-1 CSD forms a homodimer in solution, and we observed that two residues, Tyr-99 and Asp-105, at the dimer interface are important for YB-1 CSD dimerization. Substituting these two residues with Ala reduced CSD's RNA-binding activity and abrogated the splicing activation of YB-1 targets. The YB-1 CSD-RNA structures presented here at atomic resolution provide mechanistic insights into gene expression regulated by CSD-containing proteins.

Screening and identification of novel specific markers of breast cancer stem cells

Breast cancer is the leading cause of death among women worldwide. Until recent years, triple negative breast cancer could be divided into 6 types according to different biomarkers with the development of sequence and microarray technology. However, these results rarely have therapeutic impact and still lack validation with the string criteria of clinical studies. Therefore, the present study aimed to screen novel markers of breast cancer stem cells and to verify the specificity in vitro and in vivo. In the present study, screening for phages specifically binding to breast cancer stem cells was performed, positive phage DNAs were extracted, and polypeptides were synthesized and labeled with FITC. The specificity of the polypeptides was identified in vitro and in vivo. Breast cancer stem cells were cultured and identified by flow cytometry. A phage random-peptide library was amplified and screened by culturing with breast cancer cells and breast cancer stem cells. The positive phage was identified by ELISA, and positive phage DNA was extracted. The DNA pellet was isolated and sent for external sequencing with the primer −96 gIII. Based on the sequencing results, a polypeptide was synthesized and labeled with FITC. The specificity to breast cancer stem cells was identified in vivo and vitro. Following three rounds of screening, the phage was enriched ~200-fold. Immunofluorescence demonstrated that two randomly selected phage clones, B8 and A3, had specific affinity to breast cancer stem cells. The results of the present study indicated that phage polypeptides that specifically bind to breast cancer stem cells were successfully screened through stem cell enrichment and phage display technology, which may be beneficial for targeted therapy and further study of breast cancer stem cells.

Oncogenic Y-box binding protein-1 as an effective therapeutic target in drug-resistant cancer

Y-box binding protein-1 (YBX1), a multifunctional oncoprotein containing an evolutionarily conserved cold shock domain, dysregulates a wide range of genes involved in cell proliferation and survival, drug resistance, and chromatin destabilization by cancer. Expression of a multidrug resistance-associated ATP binding cassette transporter gene, ABCB1, as well as growth factor receptor genes, EGFR and HER2/ErbB2, was initially discovered to be transcriptionally activated by YBX1 in cancer cells. Expression of other drug resistance-related genes, MVP/LRP, TOP2A, CD44, CD49f, BCL2, MYC, and androgen receptor (AR), is also transcriptionally activated by YBX1, consistently indicating that YBX1 is involved in tumor drug resistance. Furthermore, there is strong evidence to support that nuclear localization and/or overexpression of YBX1 can predict poor outcomes in patients with more than 20 different tumor types. YBX1 is phosphorylated by kinases, including AKT, p70S6K, and p90RSK, and translocated into the nucleus to promote the transcription of resistance- and malignancy-related genes. Phosphorylated YBX1, therefore, plays a crucial role as a potent transcription factor in cancer. Herein, a novel anticancer therapeutic strategy is presented by targeting activated YBX1 to overcome drug resistance and malignant progression.

Nectin-1 Expression in Colorectal Cancer: Is There a Group of Patients with High Risk for Early Disease Recurrence?

BACKGROUND

Despite improvements in therapy of colorectal cancer, some patients will present occurrence of recurrence either locally or distantly. Tumor metastasis constitutes the major cause of cancer-associated morbidity and mortality. Nectin-1 belongs to the family of immunoglobulin-like cell adhesion molecules that contribute to the formation of cell-cell adhesions and regulate a series of cellular activities including cell polarization, differentiation, movement, proliferation, and survival. Expression of Nectin-1 in malignant tumors has been associated with aggressive tumor phenotypes.

OBJECTIVES

The aim of the present study was to assess Nectin-1 expression patterns in colorectal cancer and to investigate its clinical significance.

METHODS

Nectin-1 expression was assessed via immunohistochemistry in surgical specimens of a cohort comprised of 111 patients with primary resectable colorectal cancer. Results were correlated with clinicopathological characteristics and survival data. Progression-free survival was defined as the primary outcome of the present study.

RESULTS

Nectin-1 was strongly expressed in the cytoplasm of colorectal cancer cells. High Nectin-1 expression was associated with advanced stage of disease (p = 0.012) and lymph node metastasis (p = 0.007). Progression-free survival of patients exhibiting high expression of Nectin-1 in the first 36 months after surgery was significantly worse compared to patients with low expression of Nectin-1 (55.7%, 95% CI = 47-70, vs. 82.1%, 95% CI = 69-93, p = 0.014) and independent of other clinicopathological characteristics (HR = 0.389, 95% CI = 0.156-0.972, p = 0.043).

CONCLUSION

Nectin-1 expression in colorectal cancer is associated with a significantly worse 3-year progression-free survival identifying therefore a group of patients with high risk for early disease recurrence.

YB-1 modulates the drug resistance of glioma cells by activation of MDM2/p53 pathway

Background

Y-box-binding protein-1 (YB-1) is aberrantly expressed in a variety of cancers. However, the biological functional role of YB-1 in glioma is not yet clear.

Methods

The expression of MDM2 and YB-1 was analyzed by real time PCR. Overexpression and knockdown of YB-1 in glioma cells were created by transfection of pcDNA-YB-1 and siRNA against YB-1, respectively. Cell viability was performed by CCK8 assay.

Results

Our findings showed that glioma tissues had higher expressions of YB-1 than that in cancer-free tissues in 54 glioma patients, which were also positively correlated with Murine MDM2 expression. Overexpression of YB-1 or MDM2 renders a drug resistance feature in glioma cell exposed to temozolomide (TMZ), by directly targeting p53. Genetic or chemical inhibition of MDM2 significantly blocked YB-1-modulated response of glioma cells to TMZ. Moreover, inhibition of YB-1 or MDM2 reduced glioma cells metastasis and mortality in mice.

Conclusion

YB-1 facilitates the resistance of glioma cells to TMZ by direct activation of MDM2/p53 signaling and represents a promising molecular target for glioma treatment.

Prevention of breast cancer by dietary polyphenols-role of cancer stem cells

Breast cancer is a common malignancy with poor prognosis. Cancer cells are heterogeneous and cancer stem cells (CSCs) are primarily responsible for tumor relapse, treatment-resistance and metastasis, so for breast cancer stem cells (BCSCs). Diets are known to be associated with carcinogenesis. Food-derived polyphenols are able to attenuate the formation and virulence of BCSCs, implying that these compounds and their analogs might be promising agents for preventing breast cancer. In the present review, we summarized the origin and surface markers of BCSCs and possible mechanisms responsible for the inhibitory effects of polyphenols on BCSCs. The suppressive effects of common dietary polyphenols against BCSCs, such as curcumin, epigallocatechin gallate (EGCG) and related polyphenolic compounds were further discussed.

Cancer stem cells as a therapeutic target in bladder cancer

Bladder cancer is one of the most prevalent genitourinary cancers responsible for about 150,000 deaths per year worldwide. Currently, several treatments, such as endoscopic and open surgery, appended by local or systemic immunotherapy, chemotherapy, and radiotherapy are used to treat this malignancy. However, the differences in treatment outcome among patients suffering from bladder cancer are considered as one of the important challenges. In recent years, cancer stem cells, representing a population of undifferentiated cells with stem-cell like properties, have been eyed as a major culprit for the high recurrence rate in superficial papillary bladder cancer. Cancer stem cells have been reported to be resistant to conventional treatments, such as chemotherapy, radiation, and immunotherapy, which induce selective pressure on tumoral populations resulting in selection and growth of the resistant cells. Therefore, targeting the therapeutic aspects of cancer stem cells in bladder cancer may be promising. In this study, we briefly discuss the biology of bladder cancer and then address the possible relationship between molecular biology of bladder cancer and cancer stem cells. Subsequently, the mechanisms of resistance applied by cancer stem cells against the conventional therapeutic tools, especially chemotherapy, are discussed. Moreover, by emphasizing the biomarkers described for cancer stem cells in bladder cancer, we have provided, described, and proposed targets on cancer stem cells for therapeutic interventions and, finally, reviewed some immunotargeting strategies against bladder cancer stem cells.

Recent Advances in the Studies of Molecular Mechanisms Regulating Multidrug Resistance in Cancer Cells

Here we present new approaches to better understanding multidrug resistance (MDR) development in cancer cells, such as identification of components of a complex process of MDR evolution. Recent advances in the studies of MDR are discussed: 1) chemotherapy agents might be involved in the selection of cancer stem cells resulting in the elevated drug resistance and enhanced tumorigenicity; 2) cell-cell interactions have a great effect on the MDR emergence and evolution; 3) mechanotransduction is an important signaling mechanism in cell-cell interactions; 4) proteins of the ABC transporter family which are often involved in MDR might be transferred between cells via microvesicles (epigenetic MDR regulation); 5) proteins providing cell-to-cell transfer of functional P-glycoprotein (MDR1 protein) via microvesicles have been investigated; 6) P-glycoprotein may serve to regulate apoptosis, as well as transcription and translation of target genes/proteins. Although proving once again that MDR is a complex multi-faceted process, these data open new approaches to overcoming it.

Expression and network analysis of YBX1 interactors for identification of new drug targets in lung adenocarcinoma

Y-Box Binding protein 1 (YBX-1) is known to be involved in various types of cancers. It's interactors also play major role in various cellular functions. Present work aimed to study the expression profile of the YBX-1 interactors during lung adenocarcinoma (LUAD). The differential expression analysis involved 57 genes from 95 lung adenocarcinoma samples, construction of gene network and topology analysis. A Total of 43 genes were found to be differentially expressed from which 17 genes were found to be down regulated and 26 genes were up-regulated. We observed that Polyadenylate-binding protein 1 (PABPC1), a protein involved in YBX1 translation, is highly correlated with YBX1. The interaction network analysis for a differentially expressed non-coding RNA Growth Arrest Specific 5 (GAS5) suggests that two proteins namely, Growth Arrest Specific 2 (GAS2) and Peripheral myelin protein 22 (PMP22) are potentially involved in LUAD progression. The network analysis and differential expression suggests that Collagen type 1 alpha 2 (COL1A2) can be potential biomarker and target for LUAD.

Downregulation of Bmi1 in breast cancer stem cells suppresses tumor growth and proliferation

Targeting cancer stem cells during initial treatment is important to reduce incidence of recurrent disease. Bmi1 has been associated with cancer stem cell self-renewal and aggressive disease. The purpose of this study was to determine the effects of downregulation of Bmi1 in breast cancer stem cells in order to target and eliminate the stem cell population in the tumor mass. Bmi1 was downregulated using two approaches in the mouse breast cancer stem cell line FMMC 419II—a small molecule inhibitor (PTC 209) and stable transfection with a Bmi1 shRNA plasmid. The functional effect of Bmi1 downregulation was tested in vitro and in vivo. Each approach led to decreased Bmi1 expression that correlated with an inhibition of cancer stem cell properties in vitro including cell cycle arrest and reduced mammosphere forming potential, and a decrease in tumor mass in vivo after either intra-tumoral or systemic nanoparticle-targeted delivery of anti-Bmi1. These results show that inhibiting Bmi1 expression in breast cancer stem cells could be important for the complete elimination of tumor and potentially preventing disease relapse.

The multifunctional protein YB-1 potentiates PARP1 activity and decreases the efficiency of PARP1 inhibitors

Y-box-binding protein 1 (YB-1) is a multifunctional cellular factor overexpressed in tumors resistant to chemotherapy. An intrinsically disordered structure together with a high positive charge peculiar to YB-1 allows this protein to function in almost all cellular events related to nucleic acids including RNA, DNA and poly(ADP-ribose) (PAR). In the present study we show that YB-1 acts as a potent poly(ADP-ribose) polymerase 1 (PARP1) cofactor that can reduce the efficiency of PARP1 inhibitors. Similarly to that of histones or polyamines, stimulatory effect of YB-1 on the activity of PARP1 was significantly higher than the activator potential of Mg²⁺ and was independent of the presence of EDTA. The C-terminal domain of YB-1 proved to be indispensable for PARP1 stimulation. We also found that functional interactions of YB-1 and PARP1 can be mediated and regulated by poly(ADP-ribose).

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

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

Y-box binding protein-1 promotes hepatocellular carcinoma-initiating cell progression and tumorigenesis via Wnt/β-catenin pathway

Y-box binding protein-1 (YB-1) is a pleiotropic molecule that binds DNA to regulate genes on a transcriptional level in the nucleus and binds RNA to modulate gene translation in the cytoplasm. In our previous studies, YB-1 was also characterized as a fetal hepatic protein that regulates the maturation of hepatocytes and is upregulated during liver regeneration. Moreover, YB-1 has been shown to be expressed in human hepatocellular carcinoma (HCC). However, the role of YB-1 in HCC remains unclear. Here, we aimed to characterize the role of YB-1 in HCC. Based on the results of loss-of-function in HCC and gain-of-function in mice liver using hydrodynamic gene delivery, YB-1 promoted hepatic cells proliferation in vitro and in vivo. YB-1 was also involved in HCC cell proliferation, migration, and drug-resistance. The results of extreme limiting dilution sphere forming analysis and cancer initiating cell marker analysis were also shown that YB-1 maintained HCC initiating cells population. YB-1 also induced the epithelial-mesenchymal transition and stemness-related gene expression. Knockdown of YB-1 suppressed the expression of Wnt ligands and β-catenin, impaired Wnt/β-catenin signaling pathway and reduced the numbers of HCC initiating cells. Moreover, YB-1 displayed nuclear localization particularly in the HCC initiating cells, the EpCAM+ cells or sphere cells. Our findings suggested that YB-1 was a key factor in HCC tumorigenesis and maintained the HCC initiating cell population.

Truncated Glioma-Associated Oncogene Homolog 1 (tGLI1) Mediates Mesenchymal Glioblastoma via Transcriptional Activation of CD44

The molecular pathways driving mesenchymal glioblastoma (GBM) are still not well understood. We report here that truncated glioma-associated oncogene homolog 1 (tGLI1) is a tumor-specific transcription factor that facilitates GBM growth, is enriched in the mesenchymal subtype of GBM and glioma stem cells (GSC), and promotes mesenchymal GSC by upregulating transcription of CD44. In an orthotopic GBM xenograft mouse model, tGLI1-overexpressing tumors grew more aggressively with increased proliferation and angiogenesis compared with control and GLI1-overexpressing xenografts. tGLI1 was highly expressed in GBM clinical specimens but undetectable in normal brains, whereas GLI1 was expressed in both tissues. A tGLI1 activation signature (tGAS) correlated with glioma grade, tumor angiogenesis, and poor overall survival, and GBMs with high tGAS were enriched with mesenchymal GBM/GSC gene signatures. Neurospheres contained increased levels of tGLI1, but not GLI1, compared with the monolayer culture; mesenchymal GSC expressed more tGLI1 than proneural GSC. Ectopic tGLI1 expression enhanced the ability of mesenchymal GSC to yield neurospheres in vitro and to form tumors in mouse brains. Selective tGLI1 knockdown reduced neurosphere formation of GBM cells. tGLI1 bound to and transactivated the promoter of the CD44 gene, a marker and mediator for mesenchymal GSC, leading to its expression. Collectively, these findings advance our understanding of GBM biology by establishing tGLI1 as a novel transcriptional activator of CD44 and a novel mediator of mesenchymal GBM and GSC.Significance: These findings highlight the role of a tumor-specific gain-of-function transcription factor tGLI1 in mesenchymal glioma stem cell maintenance and mesenchymal GBM growth. Cancer Res; 78(10); 2589-600. ©2018 AACR.

Eugenol potentiates cisplatin anti-cancer activity through inhibition of ALDH-positive breast cancer stem cells and the NF-κB signaling pathway

Triple-negative breast tumors are very aggressive and contain relatively high proportion of cancer stem cells, and are resistant to chemotherapeutic drugs including cisplatin. To overcome these limitations, we combined eugenol, a natural polyphenolic molecule, with cisplatin to normalize cisplatin mediated toxicity and potential drug resistance. Interestingly, the combination treatment provided significantly greater cytotoxic and pro-apoptotic effects as compared to treatment with eugenol or cisplatin alone on several triple-negative breast cancer cells both in vitro and in vivo. Furthermore, adding eugenol to cisplatin potentiated the inhibition of breast cancer stem cells by inhibiting ALDH enzyme activity and ALDH-positive tumor initiating cells. We provide also clear evidence that eugenol potentiates cisplatin inhibition of the NF-κB signaling pathway. Indeed, the binding of NF-κB to its cognate binding sites present in the promoters of IL-6 and IL-8 was dramatically reduced, which led to potent down-regulation of the IL-6 and IL-8 cytokines upon combination treatment relative to the single agents. Similar effects were observed on proliferation, inhibition of epithelial-to-mesenchymal transition and stemness markers in tumor xenografts. These results provide strong preclinical justification for combining cisplatin with eugenol as therapeutic approach for triple-negative breast cancers through targeting the resistant ALDH-positive cells and inhibiting the NF-κB pathway.

High YBX1 expression indicates poor prognosis and promotes cell migration and invasion in nasopharyngeal carcinoma

Y-box binding protein-1 (YBX1) is a multifunctional protein and often acts as an indicator of poor prognosis in cancers. Increasing evidence has shown that the levels of YBX1 protein were closely associated with multidrug resistance, relapse, metastasis and poor prognosis in cancers. However, its role in nasopharyngeal carcinoma (NPC) metastasis remains unknown. In our study, we discovered that the expression of YBX1 was increased in nasopharyngeal carcinoma tissues. YBX1 protein levels positively correlated with T stage and metastasis of NPC patients. Moreover, expression of YBX1 was negatively correlated with membrane E-cadherin levels and positively correlated with Vimentin expression. In vitro, the expression of YBX1 was closely related to the invasive and migratory ability of nasopharyngeal carcinoma cells. Knockdown of YBX1 inhibited migration and invasion in 5-8F cells, and over-expression of YBX1 promoted CNE1 cells migration and invasion. Transforming growth factor-β1 (TGF-β1) treatment led to epithelial-to-mesenchymal transition (EMT) in CNE1 cells accompanied by elevated YBX1 expression. On the contrary, knockdown of YBX1 partially inhibited the TGF-β1-induced CNE1 cell migration, together with changes of EMT-associated markers. Our study revealed that TGF-β1/YBX1 signaling might be one of novel mechanisms mediating EMT in NPC, providing a new target for the treatment of nasopharyngeal carcinoma.