Perspective: Cooperation of Nanog, NF-κΒ, and CXCR4 in a regulatory network for directed migration of cancer stem cells

Study of the regulatory elements of the Ovalbumin gene promoter using CRISPR technology in chicken cells

BACKGROUND

Hormone-dependent promoters are very efficient in transgene expression. Plasmid-based reporter assays have identified regulatory sequences of the Ovalbumin promoter that are involved in response to estrogen and have shown that the deletion of the steroid-dependent regulatory element (SDRE) and negative regulatory element (NRE) leads to a steroid-independent expression of a reporter. However, the functional roles of these regulatory elements within the native genomic context of the Ovalbumin promoter have not been evaluated.

RESULTS

In this study, we show that the negative effects of the NRE element on the Ovalbumin gene can be counteracted by CRISPR interference. We also show that the CRISPR-mediated deletion of SDRE and NRE promoter elements in a non-oviduct cell can lead to the significant expression of the Ovalbumin gene. In addition, the targeted knock-in of a transgene reporter in the Ovalbumin coding region and its expression confirms that the truncated promoter of the Ovalbumin gene can be efficiently used for an estrogen-independent expression of a foreign gene.

CONCLUSIONS

The methodology applied in this paper allowed the study of promoter regulatory sequences in their native nuclear organization.

The Concept of Cancer Stem Cells: Elaborating on ALDH1B1 as an Emerging Marker of Cancer Progression

Cancer is a multifactorial, complex disease exhibiting extraordinary phenotypic plasticity and diversity. One of the greatest challenges in cancer treatment is intratumoral heterogeneity, which obstructs the efficient eradication of the tumor. Tumor heterogeneity is often associated with the presence of cancer stem cells (CSCs), a cancer cell sub-population possessing a panel of stem-like properties, such as a self-renewal ability and multipotency potential. CSCs are associated with enhanced chemoresistance due to the enhanced efflux of chemotherapeutic agents and the existence of powerful antioxidant and DNA damage repair mechanisms. The distinctive characteristics of CSCs make them ideal targets for clinical therapeutic approaches, and the identification of efficient and specific CSCs biomarkers is of utmost importance. Aldehyde dehydrogenases (ALDHs) comprise a wide superfamily of metabolic enzymes that, over the last years, have gained increasing attention due to their association with stem-related features in a wide panel of hematopoietic malignancies and solid cancers. Aldehyde dehydrogenase 1B1 (ALDH1B1) is an isoform that has been characterized as a marker of colon cancer progression, while various studies suggest its importance in additional malignancies. Here, we review the basic concepts related to CSCs and discuss the potential role of ALDH1B1 in cancer development and its contribution to the CSC phenotype.

Role of the Hypoxic-Secretome in Seed and Soil Metastatic Preparation

During tumor growth, the delivery of oxygen to cells is impaired due to aberrant or absent vasculature. This causes an adaptative response that activates the expression of genes that control several essential processes, such as glycolysis, neovascularization, immune suppression, and the cancer stemness phenotype, leading to increased metastasis and resistance to therapy. Hypoxic tumor cells also respond to an altered hypoxic microenvironment by secreting vesicles, factors, cytokines and nucleic acids that modify not only the immediate microenvironment but also organs at distant sites, allowing or facilitating the attachment and growth of tumor cells and contributing to metastasis. Hypoxia induces the release of molecules of different biochemical natures, either secreted or inside extracellular vesicles, and both tumor cells and stromal cells are involved in this process. The mechanisms by which these signals that can modify the premetastatic niche are sent from the primary tumor site include changes in the extracellular matrix, recruitment and activation of different stromal cells and immune or nonimmune cells, metabolic reprogramming, and molecular signaling network rewiring. In this review, we will discuss how hypoxia might alter the premetastatic niche through different signaling molecules.

CD44 is a prognostic biomarker and correlated with immune infiltrates in gastric cancer

Objective

Gastric carcinoma is the most common malignant tumour of the human digestive system worldwide. CD44 serves as a marker for several tumour stem cells, including gastric cancer. However, the prognostic value of CD44 and its correlation with immune infiltration in gastric cancer remain unclear.

Methods

The relative expression level of CD44 RNA in gastric cancer was analysed in the TCGA and GEPIA2 databases and validated in the GEO database. Differences in CD44 between gastric cancer cell lines and normal cells were detected by real-time PCR, and the HPA database was used to analyse the differential expression of CD44 protein in gastric cancer and normal tissues. The effect of CD44 on the proliferation and migration of gastric cancer cells was detected by CCK8 and transwell assays. UALCAN was used to analyse the relationship between CD44 expression and clinical parameters, and the Kaplan‒Meier Plotter was used to evaluate the prognostic value, including overall survival (OS), progression-free survival (PFS) and post-progression survival (PPS). The CD44 gene and protein interaction network was constructed by using the Linked Omics, GeneMANIA, STRING and DisGeNET databases. GO and KEGG analyses and GSEA of CD44 were performed by using R language. The correlation between CD44 and immune infiltration was explored by using the TIMER, CIBERSORT and GEPIA databases.

Results

CD44 is highly expressed in gastric cancer compared with normal tissues. Inhibition of proliferation and migration of gastric cancer cells after CD44 knockdown was observed. The UALCAN database showed that CD44 was independent of sex in gastric cancer but correlated with cancer stage and lymph node metastasis. Kaplan‒Meier Plotter online analysis showed that OS, PFS and PPS were prolonged in the CD44 low-expression group. GO and KEGG analyses and GSEA results showed that CD44 was mainly located in the endoplasmic reticulum and the extracellular matrix containing collagen, which was mainly involved in protein digestion and absorption. TIMER, CIBERSORT and GEPIA showed that CD44 was associated with infiltrating immune cells and thereby affected survival prognosis.

Conclusion

CD44 is highly expressed in gastric cancer and is an independent prognostic factor associated with immune invasion, which can be used as a candidate prognostic biomarker to determine the prognosis associated with gastric immune invasion.

Regulation of Tumor and Metastasis Initiation by Chemokine Receptors

Tumor-initiating cells (TICs) are a rare sub-population of cells within the bulk of a tumor that are major contributors to tumor initiation, metastasis, and chemoresistance. TICs have a stem-cell-like phenotype that is dictated by the expression of master regulator transcription factors, including OCT4, NANOG, and SOX2. These transcription factors are expressed via activation of multiple signaling pathways that drive cancer initiation and progression. Importantly, these same signaling pathways can be activated by select chemokine receptors. Chemokine receptors are increasingly being revealed as major drivers of the TIC phenotype, as their signaling can lead to activation of stemness-controlling transcription factors. Additionally, the cell surface expression of chemokine receptors provides a unique therapeutic target to disrupt signaling pathways that control the expression of master regulator transcription factors and the TIC phenotype. This review summarizes the master regulator transcription factors known to dictate the TIC phenotype, along with the complex signaling pathways that can mediate their expression and the chemokine receptors that are most upstream of this phenotype.

Histone Deacetylases Cooperate with NF-κB to Support the Immediate Migratory Response after Zebrafish Pronephros Injury

Acute kidney injury (AKI) is commonly associated with severe human diseases, and often worsens the outcome in hospitalized patients. The mammalian kidney has the ability to recover spontaneously from AKI; however, little progress has been made in the development of supportive treatments. Increasing evidence suggest that histone deacetylases (HDAC) and NF-κB promote the pathogenesis of AKI, and inhibition of Hdac activity has a protective effect in murine models of AKI. However, the role of HDAC at the early stages of recovery is unknown. We used the zebrafish pronephros model to study the role of epigenetic modifiers in the immediate repair response after injury to the tubular epithelium. Using specific inhibitors, we found that the histone deacetylase Hdac2, Hdac6, and Hdac8 activities are required for the repair via collective cell migration. We found that hdac6, hdac8, and nfkbiaa expression levels were upregulated in the repairing epithelial cells shortly after injury. Depletion of hdac6, hdac8, or nfkbiaa with morpholino oligonucleotides impaired the repair process, whereas the combined depletion of all three genes synergistically suppressed the recovery process. Furthermore, time-lapse video microscopy revealed that the lamellipodia and filopodia formation in the flanking cells was strongly reduced in hdac6-depleted embryos. Our findings suggest that Hdac activity and NF-κB are synergistically required for the immediate repair response in the zebrafish pronephros model of AKI, and the timing of HDAC inhibition might be important in developing supportive protocols in the human disease.

Synthesis and Evaluation of Novel Tetrahydronaphthyridine CXCR4 Antagonists with Improved Drug-like Profiles

Our first-generation CXCR4 antagonist TIQ15 was rationally modified to improve drug-like properties. Introducing a nitrogen atom into the aromatic portion of the tetrahydroisoquinoline ring led to several heterocyclic variants including the 5,6,7,8-tetrahydro-1,6-naphthyridine series, greatly reducing the inhibition of the CYP 2D6 enzyme. Compound 12a demonstrated the best overall properties after profiling a series of isomeric tetrahydronaphthyridine analogues in a battery of biochemical assays including CXCR4 antagonism, CYP 2D6 inhibition, metabolic stability, and permeability. The butyl amine side chain of 12a was substituted with various lipophilic groups to improve the permeability. These efforts culminated in the discovery of compound 30 as a potent CXCR4 antagonist (IC50 = 24 nM) with diminished CYP 2D6 activity, improved PAMPA permeability (309 nm/s), potent inhibition of human immunodeficiency virus entry (IC50 = 7 nM), a cleaner off-target in vitro safety profile, lower human ether a-go-go-related gene channel activity, and higher oral bioavailability in mice (% FPO = 27) compared to AMD11070 and TIQ15.

Reduction in O-glycome induces differentially glycosylated CD44 to promote stemness and metastasis in pancreatic cancer

Aberrant protein glycosylation has been shown to have a significant contribution in aggressive cancer, including pancreatic cancer (PC). Emerging evidence has implicated the involvement of cancer stem cells (CSCs) in PC aggressiveness; however, the contribution of glycosylation on self-renewal properties and maintenance of CSC is understudied. Here, using several in vitro and in vivo models lacking C1GALT1 expression, we identified the role of aberrant O-glycosylation in stemness properties and aggressive PC metastasis. A loss in C1GALT1 was found to result in the truncation of O-glycosylation on several glycoproteins with an enrichment of Tn carbohydrate antigen. Mapping of Tn-bearing glycoproteins in C1GALT1 KO cells identified significant Tn enrichment on CSC glycoprotein CD44. Notably, a loss of C1GALT1 in PC cells was found to enhance CSC features (side population-SP, ALDH1+, and tumorspheres) and self-renewal markers NANOG, SOX9, and KLF4. Furthermore, a loss of CD44 in existing C1GALT1 KO cells decreased NANOG expression and CSC features. We determined that O-glycosylation of CD44 activates ERK/NF-kB signaling, which results in increased NANOG expression in PC cells that facilitated the alteration of CSC features, suggesting that NANOG is essential for PC stemness. Finally, we identified that loss of C1GALT1 expression was found to augment tumorigenic and metastatic potential, while an additional loss of CD44 in these cells reversed the effects. Overall, our results identified that truncation of O-glycans on CD44 increases NANOG activation that mediates increased CSC activation.

The Embryonic Key Pluripotent Factor NANOG Mediates Glioblastoma Cell Migration via the SDF1/CXCR4 Pathway

NANOG is a key transcription factor required for maintaining pluripotency of embryonic stem cells. Elevated NANOG expression levels have been reported in many types of human cancers, including lung, oral, prostate, stomach, breast, and brain. Several studies reported the correlation between NANOG expression and tumor metastasis, revealing itself as a powerful biomarker of poor prognosis. However, how NANOG regulates tumor progression is still not known. We previously showed in medaka fish that Nanog regulates primordial germ cell migration through Cxcr4b, a chemokine receptor known for its ability to promote migration and metastasis in human cancers. Therefore, we investigated the role of human NANOG in CXCR4-mediated cancer cell migration. Of note, we found that NANOG regulatory elements in the CXCR4 promoter are functionally conserved in medaka fish and humans, suggesting an evolutionary conserved regulatory axis. Moreover, CXCR4 expression requires NANOG in human glioblastoma cells. In addition, transwell assays demonstrated that NANOG regulates cancer cell migration through the SDF1/CXCR4 pathway. Altogether, our results uncover NANOG-CXCR4 as a novel pathway controlling cellular migration and support Nanog as a potential therapeutic target in the treatment of Nanog-dependent tumor progression.

Regulation of Chromatin Organization in Cell Stemness: The Emerging Role of Long Non-coding RNAs

Chromatin is organized as chromosome territories in the nucleus of an interphase cell. The cell-type- and cell-state-specific organization of chromatin including the location, volume, compaction level, and spatial arrangement of chromosome territories are the major determinants of genome function. In addition, in response to different signaling stimuli and regulatory cues, it is the dynamic adaptation of chromatin structure that establishes and organizes transcriptional programs. It is known that varying levels of stemness are defined by gene regulatory networks. Accordingly, chromatin is the main milieu to host the transcriptional programs and gene regulatory networks responsible for the stemness status of a cell. In this review, our current understanding of the spatial organization of chromatin and the ways by which it defines stemness are discussed. In particular, the role of lncRNAs that regulate and affect chromatin organization and stemness properties are delineated. These roles can be categorized into the topics of specific binding to and epigenetic regulation of the promoter of pluripotency genes, their interaction with transcription factors, coordinating the intra- and inter-chromosomal looping of pluripotency-related genes, and their RNA-independent functions. This review brings together the results of studies that have begun to clarify the emerging roles of lncRNAs in the regulation of chromatin organization adapted for stemness and cancer plasticity.

Cancer stem cell secretome in the tumor microenvironment: a key point for an effective personalized cancer treatment

Cancer stem cells (CSCs) represent a tumor subpopulation responsible for tumor metastasis and resistance to chemo- and radiotherapy, ultimately leading to tumor relapse. As a consequence, the detection and eradication of this cell subpopulation represent a current challenge in oncology medicine. CSC phenotype is dependent on the tumor microenvironment (TME), which involves stem and differentiated tumor cells, as well as different cell types, such as mesenchymal stem cells, endothelial cells, fibroblasts and cells of the immune system, in addition to the extracellular matrix (ECM), different in composition to the ECM in healthy tissues. CSCs regulate multiple cancer hallmarks through the interaction with cells and ECM in their environment by secreting extracellular vesicles including exosomes, and soluble factors such as interleukins, cytokines, growth factors and other metabolites to the TME. Through these factors, CSCs generate and activate their own tumor niche by recruiting stromal cells and modulate angiogenesis, metastasis, resistance to antitumor treatments and their own maintenance by the secretion of different factors such as IL-6, VEGF and TGF-ß. Due to the strong influence of the CSC secretome on disease development, the new antitumor therapies focus on targeting these communication networks to eradicate the tumor and prevent metastasis, tumor relapse and drug resistance. This review summarizes for the first time the main components of the CSC secretome and how they mediate different tumor processes. Lastly, the relevance of the CSC secretome in the development of more precise and personalized antitumor therapies is discussed.

Recent developments in unraveling signaling mechanisms underlying drug resistance due to cancer stem-like cells

Resistance in cancer cells to therapeutic measures is challenging and requires a rigorous delineation of the underlying mechanisms. Emerging findings reflect the characteristics of tumor cells to do the reprogramming of signaling machinery in order to overturn the therapeutic responses. Recent evidence shows that the tumor acquires drug resistance due to the presence of cancer stem cells (CSCs). Hence the understanding that how tumor cells reprogram their signaling mechanisms converging towards the stemness of CSCs is imperative for novel and effective therapy. This review outlines the current updates on how CSC-associated signaling pathways and its enhanced stemness trigger the development of drug resistance. Furthermore, we also discussed the strategies with a combinational approach that can simultaneously target both CSC-induced stemness and the resistance-related signaling pathways, which may provide an optimal outcome to overcome the problem of drug resistance in cancer therapy.

Promoter methylation, transcription, and retrotransposition of LINE-1 in colorectal adenomas and adenocarcinomas

BACKGROUND

The methylation of the CpG islands of the LINE-1 promoter is a tight control mechanism on the function of mobile elements. However, simultaneous quantification of promoter methylation and transcription of LINE-1 has not been performed in progressive stages of colorectal cancer. In addition, the insertion of mobile elements in the genome of advanced adenoma stage, a precancerous stage before colorectal carcinoma has not been emphasized. In this study, we quantify promoter methylation and transcripts of LINE-1 in three stages of colorectal non-advanced adenoma, advanced adenoma, and adenocarcinoma. In addition, we analyze the insertion of LINE-1, Alu, and SVA elements in the genome of patient tumors with colorectal advanced adenomas.

METHODS

LINE-1 hypomethylation status was evaluated by absolute quantitative analysis of methylated alleles (AQAMA) assay. To quantify the level of transcripts for LINE-1, quantitative RT-PCR was performed. To find mobile element insertions, the advanced adenoma tissue samples were subjected to whole genome sequencing and MELT analysis.

RESULTS

We found that the LINE-1 promoter methylation in advanced adenoma and adenocarcinoma was significantly lower than that in non-advanced adenomas. Accordingly, the copy number of LINE-1 transcripts in advanced adenoma was significantly higher than that in non-advanced adenomas, and in adenocarcinomas was significantly higher than that in the advanced adenomas. Whole-genome sequencing analysis of colorectal advanced adenomas revealed that at this stage polymorphic insertions of LINE-1, Alu, and SVA comprise approximately 16%, 51%, and 74% of total insertions, respectively.

CONCLUSIONS

Our correlative analysis showing a decreased methylation of LINE-1 promoter accompanied by the higher level of LINE-1 transcription, and polymorphic genomic insertions in advanced adenoma, suggests that the early and advanced polyp stages may host very important pathogenic processes concluding to cancer.

SDF-1/CXCR4 induces cell invasion through CD147 in squamous cell carcinoma of the hypopharynx

Hypopharyngeal squamous cell carcinoma (SCC) has a poor prognosis due to local invasion and metastasis. The chemokine receptor CXC chemokine receptor type 4 (CXCR4) and its ligand, stromal cell-derived factor 1 (SDF-1), play roles in tumor progression through unclear mechanisms. For the present study, we used a hypopharyngeal SCC cell line, FaDu, expressing CXCR4. We found that SDF-1 promotes migration and invasion of the FaDu cells. In addition, AMD3100, a specific antagonist of CXCR4, inhibited the binding of SDF-1 to CXCR4, resulting in a significant decrease in the FaDu cell migration induced by SDF-1. Stimulation of CXCR4 with SDF-1 induced an increase in the expression of CD147, a cell membrane protein; and this CD147 upregulation was abrogated by AMD3100. CD147 function-blocking antibodies also abolished the SDF-1-induced FaDu invasiveness. Our results suggested that SDF-1/CXCR4 mediate hypopharyngeal SCC cell migration and that CD147 is involved in the SDF-1/CXCR4-related tumor progression.

FtH-Mediated ROS Dysregulation Promotes CXCL12/CXCR4 Axis Activation and EMT-Like Trans-Differentiation in Erythroleukemia K562 Cells

The cell-microenvironment communication is essential for homing of hematopoietic stem cells in stromal niches. Recent evidences support the involvement of epithelial-to-mesenchymal (EMT) process in hematopoietic stem cell homeostasis as well as in leukemia cells invasiveness and migration capability. Here, we demonstrate that the alteration of iron homeostasis and the consequent increase of redox metabolism, mediated by the stable knock down of ferritin heavy chain (FtH), enhances the expression of CXCR4 in K562 erythroleukemia cells, thus promoting CXCL12-mediated motility. Indeed, addition of the CXCR4 receptor antagonist AMD3100 reverts this effect. Upon FtH knock down K562 cells also acquire an “EMT-like” phenotype, characterized by the increase of Snail, Slug and Vimentin with the parallel loss of E-cadherin. By using fibronectin as substrate, the cell adhesion assay further shows a reduction of cell adhesion capability in FtH-silenced K562 cells. Accordingly, confocal microscopy shows that adherent K562 control cells display a variety of protrusions while FtH-silenced K562 cells remain roundish. These phenomena are largely due to the reactive oxygen species (ROS)-mediated up-regulation of HIF-1α/CXCR4 axis which, in turn, promotes the activation of NF-κB and the enhancement of EMT features. These data are confirmed by treatments with either N-acetylcysteine (NAC) or AMD3100 or NF-κB inhibitor IκB-alpha which revert the FtH-silenced K562 invasive phenotype. Overall, our findings demonstrate the existence of a direct relationship among iron metabolism, redox homeostasis and EMT in the hematological malignancies. The effects of FtH dysregulation on CXCR4/CXCL12-mediated K562 cell motility extend the meaning of iron homeostasis in the leukemia cell microenvironment.

C-X-C Chemokine Receptor 4 in Diffuse Large B Cell Lymphoma: Achievements and Challenges

Diffuse large B cell lymphoma (DLBCL), an aggressive cancer of the B cells, is the most common subtype of non-Hodgkin lymphoma (NHL) worldwide. In China, the cases of DLBCL increase yearly. C-X-C chemokine receptor 4 (CXCR4) has been implicated in the migration and trafficking of malignant B cells in several hematological malignancies, and only a few reports have been published on the role of CXCR4 in the metastasis of DLBCL. This review summarizes the relevant perspectives on the functional mechanism, prognostic significance, and therapeutic applications of the CXCL12/CXCR4 axis in DLBCL, in particular DLBCL with bone marrow involvement.

CXCR4 and CCR7 Expression in Primary Nodal Diffuse Large B-Cell Lymphoma-A Clinical and Immunohistochemical Study

BACKGROUND

A few studies have evaluated the expression of chemokine receptors CXCR4 and CCR7 in diffuse large B-cell lymphoma (DLBCL); however, the association between CXCR4 and CCR7 with bone marrow (BM) involvement and their synergistic effect on prognosis is still unclear. Our study investigated this aspect.

METHODS

Specimens were obtained from 61 primary nodal DLBCL patients and 100 reactive proliferative lymphadenitis patients. CXCR4 and CCR7 expression levels were examined by immunohistochemical staining; the relationship between these levels and clinical parameters and the differences in overall survival were analyzed.

RESULTS

CXCR4 and CCR7 overexpression was observed in the malignant lymph node tissues from most DLBCL patients. CCR7 expression was significantly higher in the non-GCB than the GCB subtype; CXCR4 positivity rates showed no significant difference between the 2 subtypes. In DLBCL patients with BM involvement, CXCR4 was overexpressed in almost all BM samples, but CCR7 expression was low in BM. CXCR4 overexpression was associated with advanced Ann Arbor stages, MYC overexpression, and increased extranodal infiltration; CCR7 was associated with advanced Ann Arbor stages and elevated LDH. Like the case for CCR7, the survival rate of CXCR4-positive DLBCL patients was significantly lower than that of the CXCR4-negative patients. CXCR4⁺CCR7⁺ patients had the lowest survival rate.

CONCLUSIONS

There is a positive correlation between CXCR4 overexpression and BM involvement. CXCR4 and CCR7 overexpression is associated with poorer overall survival, especially in CXCR4 and CCR7 copositive patients. CXCR4, CCR7, Ki-67 index, and MYC were independent prognostic factors for DLBCL. Blocking CXCR4 and/or CCR7 can be a novel therapeutic strategy for DLBCL.

Targeting CXCL12/CXCR4 Axis in Tumor Immunotherapy

Chemokines, which have chemotactic abilities, are comprised of a family of small cytokines with 8-10 kilodaltons. Chemokines work in immune cells by trafficking and regulating cell proliferation, migration, activation, differentiation, and homing. CXCR-4 is an alpha-chemokine receptor specific for stromal-derived-factor-1 (SDF-1, also known as CXCL12), which has been found to be expressed in more than 23 different types of cancers. Recently, the SDF-1/CXCR-4 signaling pathway has emerged as a potential therapeutic target for human tumor because of its critical role in tumor initiation and progression by activating multiple signaling pathways, such as ERK1/2, ras, p38 MAPK, PLC/ MAPK, and SAPK/ JNK, as well as regulating cancer stem cells. CXCL12/CXCR4 antagonists have been produced, which have shown encouraging results in anti-cancer activity. Here, we provide a brief overview of the CXCL12/CXCR4 axis as a molecular target for cancer treatment. We also review the potential utility of targeting CXCL12/CXCR4 axis in combination of immunotherapy and/or chemotherapy based on up-to-date literature and ongoing research progress.

BORIS: a key regulator of cancer stemness

BORIS (CTCFL) is a DNA binding protein which is involved in tumorigenesis. Although, there are different opinions on the level of gene expression and function of BORIS in normal and cancer tissues, the results of many studies have classified BORIS as a protein belonging to cancer/testis (CT) genes, which are identified as a group of genes that are expressed normally in testis, and abnormally in various types of cancers. In testis, BORIS induces the expression of some male germ cell/testis specific genes, and plays crucial roles during spermatogenesis and production of sperm. In tumorigenesis, the role of BORIS in the expression induction of some CT genes and oncogenes, as well as increasing proliferation/viability of cancer cells has been demonstrated in many researches. In addition to cancer cells, some believe that BORIS is also expressed in normal conditions and plays a universal function in cell division and regulation of genes. The following is a comprehensive review on contradictory views on the expression pattern and biological function of BORIS in normal, as well as cancer cells/tissues, and presents some evidence that support the expression of BORIS in cancer stem cells (CSCs) and advanced stage/poorer differentiation grade of cancers. Boris is involved in the regulation of CSC cellular and molecular features such as self-renewal, chemo-resistance, tumorigenicity, sphere-forming ability, and migration capacity. Finally, the role of BORIS in regulating two important signaling pathways including Wnt/β-catenin and Notch in CSCs, and its ability in recruiting transcription factors or chromatin-remodeling proteins to induce tumorigenesis is discussed.

Nanog suppresses the expression of vasa by directly regulating nlk1 in the early zebrafish embryo

Nanog is a homeodomain transcription factor that is essential for maintenance of pluripotency and self-renewal of embryonic stem cells (ESCs). In the present study, we demonstrate that zebrafish Nanog (zNanog) directly binds to the promoter region of zebrafish nlk1 (znlk1) by ChIP-Seq analysis and that it up-regulates the expression of znlk1 in fibroblast-like embryonic cells of Danio rerio (ZEM-2S cells) and in zebrafish embryos at 30% epiboly both at the mRNA and protein levels. In addition, compared with control (MO-C) embryos at 30% epiboly, the mRNA and protein expression of vasa and the numbers of vasa-positive cells were increased in embryos injected with zNanog morpholino (MO-zNanog). Further, injection of znlk1 mRNA into zNanog-depleted embryos restored the expression of vasa and the number of vasa-positive cells. These data indicated that zNanog up-regulates the expression of znlk1 through directly binding to the znlk1 promoter, thereby suppressing the expression of vasa. Vasa is a marker gene for PGCs. Our results suggest that zNanog plays a role in restraint of PGC cell number through regulating the expression of znlk1 in the early embryonic development. The current results provide fundamental information to support further investigation regarding the regulatory mechanism of zNanog during the development of PGCs.

Combination treatment with dendrosomal nanocurcumin and doxorubicin improves anticancer effects on breast cancer cells through modulating CXCR4/NF-κB/Smo regulatory network

Despite advantageous antitumor properties of doxorubicin, the considerable cytotoxicity of this chemotherapeutic agent has made it necessary to develop combination treatment strategies. The aim of the current study was to investigate the possible synergism between dendrosomal nanocurcumin (DNC) and doxorubicin in eliciting anticancer effects on MDA-MB-231 metastatic breast cancer cells. The expression levels of CXCL12/CXCR4 axis and Hedgehog pathway genes were evaluated in patient-derived breast carcinoma tissues by qRT-PCR. MTT assay, Annexin V-FITC staining followed by flowcytomety and wound healing assay were used to measure the effects caused by DNC and doxorubicin, alone and in combination, on the viability, apoptosis induction, and migration of MDA-MB-231 cells, respectively. Also, qRT-PCR was exploited to analyze the expression of Smo, NF-κB and CXCR4 in cancer cells. Our results revealed that combination treatment with DNC and doxorubicin leads to significantly decreased viability, increased apoptosis, and reduced migration of breast cancer cells compared with using each drug alone. Also, combination treatment is more efficient that single treatment in reducing the expression levels of NF-κB and Smo transcripts. Our findings provide convincing support for the notion that DNC could synergistically enhance the anticancer effects of doxorubicin on metastatic breast cancer cells by improving its anti-proliferative, pro-apoptotic, and anti-migratory activities. This may be mediated, in part, by downregulating CXCR4, NF-κB, and Smo genes. Overall, the findings of the current study suggest that DNC might be used as a synergistic agent for enhancing therapeutic efficiency and reducing toxic effects of doxorubicin on breast cancer cells.

The CXCR4 antagonist plerixafor enhances the effect of rituximab in diffuse large B-cell lymphoma cell lines

Background

Diffuse large B-cell lymphoma (DLBCL) is an aggressive disease with variable clinical outcome, accounting for at least 25-30 % of adult non-Hodgkin lymphomas. Approximately one third of DLBCL patients are not cured by the currently used treatment regimen, R-CHOP. Hence, new treatment strategies are needed. Antagonizing the CXCR4 receptor might be promising since the CXCR4-CXCL12 axis is implicated in several aspects of tumor pathogenesis as well as in protection from chemotherapeutic response. In Burkitt lymphoma, the CXCR4 antagonist plerixafor has already been shown to enhance the therapeutic effect of rituximab, the immunotherapeutic agent of R-CHOP; but this is yet to be confirmed for DLBCL. We, therefore, investigated the effect of plerixafor on DLBCL cellular response to rituximab.

Methods

In this in vitro study, human DLBCL cell lines were treated with rituximab and/or plerixafor, concomitantly or in sequence. The trypan blue exclusion method and MTS-based assays were used to evaluate cellular proliferation, whereas flow cytometry was used for assessment of apoptosis status and CXCR4 surface expression level. Linear mixed effects models were used to assess statistical significance.

Results

We observed that simultaneous addition of plerixafor and rituximab resulted in a significant decrease in DLBCL cellular proliferation, compared to monotherapeutic response. The effect was dose-dependent, and concomitant administration was observed to be superior to sequential drug administration. Accordingly, the fraction of apoptotic/dead cells significantly increased following addition of plerixafor to rituximab treatment. Furthermore, exposure of DLBCL cells to plerixafor resulted in a significant decrease in CXCR4 fluorescence intensity.

Conclusions

Based on our results, implying that the anti-proliferative/pro-apoptotic effect of rituximab on DLBCL cells can be synergistically enhanced by the CXCR4 antagonist plerixafor, addition of plerixafor to the R-CHOP regimen can be suggested to improve treatment outcome for DLBCL patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s40364-016-0067-2) contains supplementary material, which is available to authorized users.

The NF-κB Pathway and Cancer Stem Cells

The NF-κB transcription factor pathway is a crucial regulator of inflammation and immune responses. Additionally, aberrant NF-κB signaling has been identified in many types of cancer. Downstream of key oncogenic pathways, such as RAS, BCR-ABL, and Her2, NF-κB regulates transcription of target genes that promote cell survival and proliferation, inhibit apoptosis, and mediate invasion and metastasis. The cancer stem cell model posits that a subset of tumor cells (cancer stem cells) drive tumor initiation, exhibit resistance to treatment, and promote recurrence and metastasis. This review examines the evidence for a role for NF-κB signaling in cancer stem cell biology.