New insight into NANOG: A novel therapeutic target for ovarian cancer (OC)

NANOG regulate the JAK/STAT3 pathway to promote trophoblast cell migration and epithelial-mesenchymal transition (EMT) in hypertensive disorders of pregnancy (HDP) through protein interaction with CDK1

PROBLEM

Hypertensive disorders of pregnancy (HDP) are a common pregnancy disease. NANOG and Cyclin-dependent kinase 1 (CDK1) are essential for regulating the function of cell proliferation and apoptosis. However, the mechanism of action in HDP is yet unclear.

METHOD

The microarray dataset GSE6573 was downloaded from the GEO database. Emt-related gene set was downloaded from Epithelial-Mesenchymal Transition gene database 2.0 were screened differentially expressed genes by bioinformatics analysis. Pathway Commons and Scansite 4.0 databases were used to predict the interaction between proteins. Placental tissue samples were collected from HDP patients and patients with uneventful pregnancies. RT-qPCR, Western blot and immunohistochemistry were used to detect the expression of NANOG, CDK1, MMP-2, MMP-9, EMT markers and the JAK/STAT3 pathway proteins. Transfection NANOG overexpression/knockdown, and CDK1 knockdown into the human chorionic trophoblast cells (HTR-8/Svneo). CCK-8, Transwell and Wound-healing assay were used to evaluate cell proliferation, invasion and migration. CO-IP and GST pull-down assays were used to confirm the protein interaction.

RESULTS

A total obtained seven EMT-related differentially expressed genes, wherein NANOG, NODAL and LIN28A had protein interaction. In the HDP patients' tissue found that NANOG and CDK1 had lower expression. NANOG overexpression promoted HTR-8/Svneo proliferation, migration and EMT, while NANOG knockdown had the opposite effect. Further a protein interaction between STAT3 and CDK1 with NANOG. NANOG overexpression downregulated the JAK/STAT3 pathway to promote HTR-8/Svneo proliferation, migration and EMT, which was reversed by CDK1 knockdown.

CONCLUSIONS

NANOG downregulated the JAK/STAT3 pathway to promote trophoblast cell proliferation, migration and EMT through protein interaction with CDK1.

Selected markers of ovarian cancer and their relation to targeted therapy (Review)

Despite advances in surgical treatment techniques and chemotherapy-including anti-angiogenic and immune poly (ADP-ribose) polymerase inhibitors, the 5-year survival rate in ovarian cancer (OC) remains low. The reasons for this are the diagnosis of cancer in advanced clinical stages, chemoresistance and cancer recurrence. New therapeutic approaches are being developed, including the search for new biomarkers that are also targets for targeted therapy. The present review describes new molecular markers with relevance to targeted therapy, which to date have been studied only in experimental research. These include the angiogenic protein angiopoietin-2, the transmembrane glycoprotein ectonucleotide pyrophosphatase/phosphodiesterase 1, the adhesion protein E-cadherin, the TIMP metallopeptidase inhibitor 1 and Kruppel-like factor 7. Drugs affecting cancer stem cells (CSCs) in OC, such as metformin and salinomycin, as well as inhibitors of CSCs markers aldehyde dehydrogenase 1 (with the drug ATRA) and the transcription factor Nanog homeobox (microRNA) are also discussed. A new approach to prevention and possible therapies under investigation such as development of vaccines containing a subpopulation of CD117(+) and CD44(+) stem cells with a promising option for use in women with OC was described.

Composition, preparation methods, and applications of nanoniosomes as codelivery systems: a review of emerging therapies with emphasis on cancer

Nanoniosome-based drug codelivery systems have become popular therapeutic instruments, demonstrating tremendous promise in cancer therapy, infection treatment, and other therapeutic domains. An emerging form of vesicular nanocarriers, niosomes are self-assembling vesicles composed of nonionic surfactants, along with cholesterol or other amphiphilic molecules. This comprehensive review focuses on how nanosystems may aid in making anticancer and antibacterial pharmaceuticals more stable and soluble. As malleable nanodelivery instruments, the composition, types, preparation procedures, and variables affecting the structure and stability of niosomes are extensively investigated. In addition, the advantages of dual niosomes for combination therapy and the administration of multiple medications simultaneously are highlighted. Along with categorizing niosomal drug delivery systems, a comprehensive analysis of various preparation techniques, including thin-layer injection, ether injection, and microfluidization, is provided. Dual niosomes for cancer treatment are discussed in detail regarding the codelivery of two medications and the codelivery of a drug with organic, plant-based bioactive compounds or gene agents. In addition, niogelosomes and metallic niosomal carriers for targeted distribution are discussed. The review also investigates the simultaneous delivery of bioactive substances and gene agents, including siRNA, microRNA, shRNA, lncRNA, and DNA. Additional sections discuss the use of dual niosomes for cutaneous drug delivery and treating leishmanial infections, Pseudomonas aeruginosa, and Mycobacterium tuberculosis. The study concludes by delineating the challenges and potential routes for nanoniosome-based pharmaceutical codelivery systems, which will be useful for nanomedicine practitioners and researchers.

Cancer stemness kinase inhibitor amcasertib: a promising therapeutic agent in ovarian cancer stem and cancer cell models with different genetic profiles

Ovarian cancer, often referred to as the 'silent killer,' is a significant contributor to mortality rates. Emerging evidence implicates Nanog as a potential therapeutic target in ovarian cancer. Amcasertib (BBI-503) is an orally administered primary class stemness kinase inhibitor that effectively targets NANOG and various cancer stem cell pathways by specifically inhibiting serine-threonine stemness kinases. This study aimed to evaluate the antineoplastic effects of Nanog inhibition, a critical transcription factor associated with pluripotency and its role in ovarian cancer tumorigenesis, using the novel therapeutic agent Amcasertib in ovarian cancer cells characterized by distinct genetic profiles. The cytotoxicity of Amcasertib was assessed in both ovarian cancer and cancer stem cell models utilizing the Xelligence-RTCA system. The impact of the determined IC50 dose on apoptosis, invasion, migration, epithelial-mesenchymal transition (EMT), cell cycle progression, colony formation, and spheroid growth was evaluated using appropriate analytical techniques. Our findings revealed that Amcasertib exhibited significant antiproliferative effects and induced apoptosis in ovarian cancer and cancer stem cells. Moreover, Amcasertib caused G1 phase arrest and impeded colony formation in MDAH-2774 cells. Additionally, Amcasertib effectively inhibited spheroid growth in OVCAR-3 and OCSC cells. Notably, it demonstrated the ability to suppress invasion and migration in MDAH-2774 and OCSC cells. Furthermore, the suppression of Nanog-mediated stem cell-like features by Amcasertib was particularly pronounced in ER-negative ovarian cancer and cancer stem cells, highlighting its high anticancer efficacy in this subgroup. These results suggest that Amcasertib holds promise as a potential standalone or combination therapy agent for the treatment of ER-negative ovarian cancer.

Regulation and signaling pathways in cancer stem cells: implications for targeted therapy for cancer

Cancer stem cells (CSCs), initially identified in leukemia in 1994, constitute a distinct subset of tumor cells characterized by surface markers such as CD133, CD44, and ALDH. Their behavior is regulated through a complex interplay of networks, including transcriptional, post-transcriptional, epigenetic, tumor microenvironment (TME), and epithelial-mesenchymal transition (EMT) factors. Numerous signaling pathways were found to be involved in the regulatory network of CSCs. The maintenance of CSC characteristics plays a pivotal role in driving CSC-associated tumor metastasis and conferring resistance to therapy. Consequently, CSCs have emerged as promising targets in cancer treatment. To date, researchers have developed several anticancer agents tailored to specifically target CSCs, with some of these treatment strategies currently undergoing preclinical or clinical trials. In this review, we outline the origin and biological characteristics of CSCs, explore the regulatory networks governing CSCs, discuss the signaling pathways implicated in these networks, and investigate the influential factors contributing to therapy resistance in CSCs. Finally, we offer insights into preclinical and clinical agents designed to eliminate CSCs.

Cancer chemotherapy and beyond: Current status, drug candidates, associated risks and progress in targeted therapeutics

Cancer is an abnormal state of cells where they undergo uncontrolled proliferation and produce aggressive malignancies that causes millions of deaths every year. With the new understanding of the molecular mechanism(s) of disease progression, our knowledge about the disease is snowballing, leading to the evolution of many new therapeutic regimes and their successive trials. In the past few decades, various combinations of therapies have been proposed and are presently employed in the treatment of diverse cancers. Targeted drug therapy, immunotherapy, and personalized medicines are now largely being employed, which were not common a few years back. The field of cancer discoveries and therapeutics are evolving fast as cancer type-specific biomarkers are progressively being identified and several types of cancers are nowadays undergoing systematic therapies, extending patients' disease-free survival thereafter. Although growing evidence shows that a systematic and targeted approach could be the future of cancer medicine, chemotherapy remains a largely opted therapeutic option despite its known side effects on the patient's physical and psychological health. Chemotherapeutic agents/pharmaceuticals served a great purpose over the past few decades and have remained the frontline choice for advanced-stage malignancies where surgery and/or radiation therapy cannot be prescribed due to specific reasons. The present report succinctly reviews the existing and contemporary advancements in chemotherapy and assesses the status of the enrolled drugs/pharmaceuticals; it also comprehensively discusses the emerging role of specific/targeted therapeutic strategies that are presently being employed to achieve better clinical success/survival rate in cancer patients.

Targeting Nanog expression increased Cisplatin chemosensitivity and inhibited cell migration in Gastric cancer cells

Regardless of significant advances in cancer treatment, gastric cancer (GC) incidence rate is increasing worldwide. As one of the main transcription factors participating in stemness, Nanog plays a pivotal role in various aspects of tumorigenesis, metastasis, and chemosensitivity. Given that, the current research intended to evaluate the potential effects of Nanog suppression on the GC cell cisplatin chemosensitivity and in vitro tumorigenesis. First, bioinformatics analysis was performed to evaluate the effect of Nanog expression on GC patients' survival. The MKN-45 human GC cells were transfected with specific siRNA targeting Nanog and/or treated with Cisplatin. Then, to study cellular viability and apoptosis, MTT assay and Annexin V/PI staining were done, respectively. Also, the scratch assay was performed to investigate cell migration, and MKN-45 cell stemness was followed using colony formation assay. Western blotting and qRT-PCR were used for gene expression analysis. The findings demonstrated that siRNA-mediated Nanog silencing strongly increased MKN-45 cell sensitivity to Cisplatin through apoptosis induction. Also, Nanog suppression combined with Cisplatin resulted in the upregulation of the Caspase-3 and Bax/Bcl-2 ratio at mRNA levels and increased Caspase-3 activation. Moreover, reduced expression of Nanog, separately or combined with Cisplatin, inhibited MKN-45 cell migration by downregulating MMP2 mRNA and protein expression levels. The results also evidenced CD44 and SOX-2 downregulation aligned with a decreased rate of MKN-45 cell colony formation ability through treatments. Besides, Nanog downregulation significantly decreased MDR-1 mRNA expression. Taken together, the results of this study indicated that Nanog could be suggested as a promising target combined with Cisplatin-based GC therapies for reducing drug side effects and improving patients' outcomes.

Epigallocatechin-3-Gallate Prevents the Acquisition of a Cancer Stem Cell Phenotype in Ovarian Cancer Tumorspheres through the Inhibition of Src/JAK/STAT3 Signaling

Three-dimensional tumorsphere cultures recapitulate the expression of several cancer stem cell (CSC) biomarkers and represent an effective in vitro platform to screen the anti-CSC properties of drugs. Whereas ovarian carcinoma is among the leading causes of death for women, ovarian CSC (OvCSC), a highly malignant subpopulation of ovarian cancer cells, is thought to be responsible for therapy resistance, metastasis, and tumor relapse. Epigallocatechin-3-gallate (EGCG), a diet-derived active polyphenol found in green tea leaves, can suppress ovarian cancer cell proliferation and induce apoptosis. However, its capacity to prevent the acquisition of cancer stemness traits in ovarian malignancies remains unclear. Here, we exploited the in vitro three-dimensional tumorsphere culture model to explore the capacity of EGCG to alter CSC biomarkers expression, signal transducing events and cell chemotaxis. Total RNA and protein lysates were isolated from human ES-2 ovarian cancer cell tumorspheres for gene assessment by RT-qPCR and protein expression by immunoblot. Real-time cell chemotaxis was assessed with xCELLigence. Compared with their parental adherent cells, tumorspheres expressed increased levels of the CSC markers NANOG, SOX2, PROM1, and Fibronectin. EGCG treatment reduced dose-dependently tumorspheres size and inhibited the transcriptional regulation of those genes. Src and JAK/STAT3 signaling pathways appeared to be relevant for CSC phenotype and chemotactic response. In conclusion, these data highlight and support the chemopreventive benefits of the diet-derived EGCG and its capacity to target intracellular transducing events that regulate the acquisition of an invasive CSC phenotype.

Dual role of quercetin in enhancing the efficacy of cisplatin in chemotherapy and protection against its side effects: a review

Chemotherapy has opened a new window in cancer therapy. However, the resistance of cancer cells has dramatically reduced the efficacy of chemotherapy. Cisplatin is a chemotherapeutic agent and its potential in cancer therapy has been restricted by resistance of cancer cells. As a consequence, the scientists have attempted to find new strategies in elevating chemotherapy efficacy. Due to great anti-tumour activity, naturally occurring compounds are of interest in polychemotherapy. Quercetin is a flavonoid with high anti-tumour activity against different cancers that can be used with cisplatin to enhance its efficacy and also are seen to sensitise cancer cells into chemotherapy. Furthermore, cisplatin has side effects such as nephrotoxicity and ototoxicity. Administration of quercetin is advantageous in reducing the adverse effects of cisplatin without compromising its anti-tumour activity. In this review, we investigate the dual role of quercetin in enhancing anti-tumour activity of cisplatin and simultaneous reduction in its adverse effects.

NANOG regulates epithelial–mesenchymal transition via AMPK / mTOR signalling pathway in ovarian cancer SKOV ‐3 and A2780 cells

NANOG engages with tumour initiation and metastasis by regulating the epithelial–mesenchymal transition (EMT) in epithelial ovarian cancer (EOC). However, its role in association with pAMPKα, and its clinical significance in EOC have not been elucidated even though AMPK is known to degrade NANOG in various human cancers. Hence, we investigated the role of pAMPKα and its association with NANOG as potential prognostic biomarkers in EOC. Both NANOG and pAMPKα expression were significantly overexpressed in EOCs comparing nonadjacent normal epithelial tissues, benign tissues, and borderline tumours. NANOG overexpression was significantly associated with poor disease‐free survival (DFS) and overall survival (OS), whereas pAMPKα overexpression was associated with good DFS and OS. Importantly, multivariate analysis revealed that the combination of high NANOG and low pAMPKα expression was a poor independent prognostic factor for DFS and was associated with platinum resistance. In ovarian cancer cell lines, siRNA‐mediated NANOG knockdown diminished migration and invasion properties by regulating the EMT process via the AMPK/mTOR signalling pathway. Furthermore, treatment with AMPK activator suppressed expression of stemness factors such as NANOG, Oct4 and Sox2. Collectively, these findings established that the combination of high NANOG and low pAMPKα expression was associated with EOC progression and platinum resistance, suggesting a potential prognostic biomarker for clinical management in EOC patients.

Role of O-GlcNAcylation on cancer stem cells: Connecting nutrient sensing to cell plasticity

Tumor growth and metastasis can be promoted by a small sub-population of cancer cells, termed cancer stem-like cells (CSCs). While CSCs possess capability in self-renewing and differentiating, the hierarchy of CSCs during tumor growth is highly plastic. This plasticity in CSCs fate and function can be regulated by signals from the tumor microenvironment. One emerging pathway in CSCs that connects the alteration in microenvironment and signaling network in cancer cells is the hexosamine biosynthetic pathway (HBP). The final product of HBP, UDP-N-acetylglucosamine (UDP-GlcNAc), is utilized for glycosylating of membrane and secreted proteins, but also nuclear and cytoplasmic proteins by the post-translational modification O-GlcNAcylation. O-GlcNAcylation and its enzyme, O-GlcNAc transferase (OGT), are upregulated in nearly all cancers and been linked to regulate many cancer cell phenotypes. Recent studies have begun to connect OGT and O-GlcNAcylation to regulation of CSCs. In this review, we will discuss the emerging role of OGT and O-GlcNAcylation in regulating fate and plasticity of CSCs, as well as the potential in targeting OGT/O-GlcNAcylation in CSCs.

Nanog, as a key cancer stem cell marker in tumor progression

Cancer stem cells (CSCs) are a small population of malignant cells that induce tumor onset and development. CSCs share similar features with normal stem cells in the case of self-renewal and differentiation. They also contribute to chemoresistance and metastasis of cancer cells, leading to therapeutic failure. To identify CSCs, multiple cell surface markers have been characterized, including Nanog, which is found at high levels in different cancers. Recent studies have revealed that Nanog upregulation has a substantial association with the advanced stages and poor prognosis of malignancies, playing a pivotal role through tumorigenesis of multiple human cancers, including leukemia, liver, colorectal, prostate, ovarian, lung, head and neck, brain, pancreatic, gastric and breast cancers. Nanog through different signaling pathways, like JAK/STAT and Wnt/β-catenin pathways, induces stemness, self-renewal, metastasis, invasiveness, and chemoresistance of cancer cells. Some of these signaling pathways are common in various types of cancers, but some have been found in one or two cancers. Therefore, this review aimed to focus on the function of Nanog in multiple cancers based on recent studies surveying the suitable approaches to target Nanog and inhibit CSCs residing in tumors to gain favorable results from cancer treatments.

The multiple faces of NANOG in cancer: a therapeutic target to chemosensitize therapy-resistant cancers

The transcription factor NANOG regulates self-renewal and pluripotency in embryonic cells, and its downregulation leads to cell differentiation. Recent studies have linked upregulation of NANOG in various cancers and the regulation of expression of different molecules, and vice versa, to induce proliferation, metastasis, invasion and chemoresistance. Thus NANOG is an oncogene that functions by inducing stem cells' circuitries and heterogeneity in cancers. Understanding NANOG's role in various cancers may lead to it becoming a therapeutic target to halt cancer progression. The NANOG network can also be targeted to resensitize resistant cancer cells to conventional therapies. The current review focuses on NANOG regulation in the various signaling networks leading to cancer progression and chemoresistance, and highlights the therapeutic aspect of targeting NANOG in various cancers.

Cancer-testis antigen ACRBP expression and serum immunoreactivity in ovarian cancer: Its association with prognosis

Introduction

Cancer testis (CT) antigens are attractive targets for cancer immunotherapy because of their expression restriction and immunogenicity. The acrosin binding protein (ACRBP) is a member of CT antigens. This study aimed to evaluate ACRBP expression and immunogenicity in ovarian cancer (OC).

Methods

The expression level of ACRBP in OC tissues, normal ovarian tissues, and cell lines was detected via quantitative real‐time polymerase chain reaction (qRT‐PCR) and immunohistochemistry. We determined the levels of ACRBP antigen and antibody in serum samples collected from patients with OC and healthy donors using enzyme‐linked immunosorbent assays (ELISA), the level of ACRBP in cell‐cultured medium was also tested.

Results

ACRBP mRNA and protein expressions were upregulated in OC tissues relative to normal tissue, especially highly expressed in epithelial ovarian cancer (EOC). Moreover, ACRBP expression was significantly correlated with International Federation of Gynecology and Obstetrics (FIGO) stage and chemosensitivity. Serological analysis showed that anti‐ACRBP antibody was detected in the sera of 16 of the 56 (28.5%) patients with OC but not in healthy donors. The area under the receiver operating characteristic curve for ACRBP antibody was 0.802 (95% confidence interval [CI]: 0.708–0.876), and the sensitivity and specificity for ACRBP antibody was 85.71% and 55.0%, respectively. Kaplan–Meier analysis revealed that the overall survival (OS) and disease‐free survival (DFS) in OC patients with high ACRBP expression were significantly lower than those with low expression (p = 0.040, p = 0.021). However, ACRBP antibody level was not associated with prognosis.

Conclusion

ACRBP expression was upregulated in OC tissues and induced humoral immune response in patients with OC, suggesting that ACRBP is a potential prognostic biomarker and a target of tumor immunotherapy for OC.

Reporter gene systems for the identification and characterization of cancer stem cells

Cancer stem cells (CSCs) are tumor cells that share functional characteristics with normal and embryonic stem cells. CSCs have increased tumor-initiating capacity and metastatic potential and lower sensitivity to chemo- and radiotherapy, with important roles in tumor progression and the response to therapy. Thus, a current goal of cancer research is to eliminate CSCs, necessitating an adequate phenotypic and functional characterization of CSCs. Strategies have been developed to identify, enrich, and track CSCs, many of which distinguish CSCs by evaluating the expression of surface markers, the initiation of specific signaling pathways, and the activation of master transcription factors that control stemness in normal cells. We review and discuss the use of reporter gene systems for identifying CSCs. Reporters that are under the control of aldehyde dehydrogenase 1A1, CD133, Notch, Nanog homeobox, Sex-determining region Y-box 2, and POU class 5 homeobox can be used to identify CSCs in many tumor types, track cells in real time, and screen for drugs. Thus, reporter gene systems, in combination with in vitro and in vivo functional assays, can assess changes in the CSCs pool. We present relevant examples of these systems in the evaluation of experimental CSCs-targeting therapeutics, demonstrating their value in CSCs research.

Nanog-mediated stem cell properties is critical for MBNL3 associated paclitaxel resistance of ovarian cancer

Paclitaxel (PTX) is the standard first-line treatment of ovarian cancer, but its efficacy is limited by multi-drug resistance. Therefore, it is crucial to identify effective drug targets to facilitate PTX-sensitivity for ovarian cancer treatment. Seventy PTX-administrated ovarian cancer patients were recruited in this study for gene expression and survival rate analyses. Muscleblind-like-3 (MBNL3) gain- and loss-of-function experiments were carried out in ovarian cancer cells (parental and PTX-resistant) and xenograft model. Cancer cell viability, apoptosis, spheroids formation, Nanog gene silencing were examined and conducted to dissect the underlying mechanism of MBNL3-mediated PTX-resistance. High expression of MBNL3 was positively correlated with PTX-resistance and poor prognosis of ovarian cancer. MBNL3 increased cell viability and decreased apoptosis in ovarian stem-like cells, through up-regulating Nanog. This study suggests the MBNL3-Nanog axis is a therapeutic target for the treatment of PTX-resistance in ovarian cancer management.

NANOG Decoy Oligodeoxynucleotide-Encapsulated Niosomes Nanocarriers: A Promising Approach to Suppress the Metastatic Properties of U87 Human Glioblastoma Multiforme Cells

Recently, advances in the synthesis and development of multifunctional nanoparticle platforms have opened up great opportunities and advantages for specifically targeted delivery of genes of interest. BSA-coated niosome structures (NISM@B) can potentially improve the efficiency in vitro delivery of nucleic acid molecules and the transfection of genes. Few studies have reported the combined use of niosomes with nucleic acid as therapeutic agents or decoy oligodeoxynucleotides (ODNs). Herein, we synthesized NISM@B to encapsulate NANOG decoy ODN (NISM@B-DEC), after which the physicochemical characteristics and in vitro and in vivo properties of NISM@B-DEC were investigated. Our results regarding physicochemical characteristics revealed that the stable niosome nanocarrier system was successfully synthesized with a regular spherical shape and narrow size distribution with proper zeta-potential values and had an appropriate biocompatibility. The ODN release from the niosome nanocarrier system exhibited controlled and pH-dependent behavior as the best models to explain the ODN release profile. NISM@B-DEC was efficiently taken up by human glioblastoma cells (U87) and significantly inhibited cell growth. Finally, blockage of the NANOG pathway by NISM@B-DEC resulted in G1 cell cycle arrest, apoptosis, and cell death. In addition, NISM@B-DEC caused a significant decrease in tumor formation and improved wound-healing efficiency of the U87 cells. These findings confirm that NISM@B-DEC could potentially suppress the metastatic ability of these cells. It can be concluded that the presented nanocarrier system can be a promising approach for targeted gene delivery in cancer therapy.

Purinergic signalling pathway: therapeutic target in ovarian cancer

Background

The lack of early diagnostic tools and the development of chemoresistance have made ovarian cancer (OC) one of the deadliest gynaecological cancers. The tumour microenvironment is characterised by the extracellular release of high levels of ATP, which is followed by the activation of P1 adenosinergic and P2 purinergic signalling systems. The sequential hydrolysis of ATP by the ectonucleotidases CD39 and CD73 generates adenosine, which creates an immune suppressive microenvironment by inhibiting the T and NK cell responses via the A2A adenosine receptor.

Main body of the abstract

In OC, adenosine-induced pAMPK pathway leads to the inhibition of cell growth and proliferation, which offers new treatment options to prevent or overcome chemoresistance. The activation of P2Y12 and P2Y1 purinergic receptors expressed in the platelets promotes epithelial-mesenchymal transition (EMT). The inhibitors of these receptors will be the effective therapeutic targets in managing OC. Furthermore, research on these signalling systems indicates an expanding field of opportunities to specifically target the purinergic receptors for the treatment of OC.

Short conclusion

In this review, we have described the complex purinergic signalling mechanism involved in the development of OC and discussed the merits of targeting the components involved in the purinergic signalling pathway.

CircMEG3 inhibits telomerase activity by reducing Cbf5 in human liver cancer stem cells

Circular RNA (CircRNA) is a newly identified special class of non-coding RNA (ncRNA) that plays an important regulatory role in the progression of certain diseases. Herein, our results indicate that CircMEG3 is downregulated expression and negatively correlated with the expression of telomerase-related gene Cbf5 in human liver cancer. Moreover, CircMEG3 inhibits the growth of human liver cancer stem cells in vivo and in vitro. CircMEG3 inhibits the expression of m6A methyltransferase METTL3 dependent on HULC. Moreover, CircMEG3 inhibits the expression of Cbf5, a component of telomere synthetase H/ACA ribonucleoprotein (RNP; catalyst RNA pseudouracil modification) through METTL3 dependent on HULC. Thereby, CircMEG3 inhibits telomerase activity and shortens telomere lifespan dependent on HULC and Cbf5 in human liver cancer stem cell. Strikingly, increased Cbf5 abrogates the ability of CircMEG3 to inhibit malignant differentiation of human liver cancer stem cells. In summary, these observations provide important basic information for finding effective liver cancer therapeutic targets.

Expression patterns and clinical significance of the potential cancer stem cell markers OCT4 and NANOG in colorectal cancer patients

Colorectal cancer (CRC) is one of the most important malignancies and causes of cancer-related deaths worldwide. Cancer stem cell markers identification could be helpful to acquire important prognostic information and develop new treatment regimens. This study aimed to evaluate the expression of OCT4 and NANOG in CRC patients and their clinical significance.

Totally 359 CRC samples were stained for OCT4 and NANOG expression using tissue microarray. The correlation between their expression and clinical and pathological features was explored.

The majority of CRC cases showed low-level expression of OCT4 (80%) and NANOG (75%). Lower expression of OCT4 was more often detected in CRC cases with no vascular involvement (P = .01). Also, a trend found between low level of OCT4 expression and absence of distant metastasis or lymph node involvement (P = .07 and P = .09, respectively). Surprisingly, a significant positive correlation was observed between NANOG expression and cellular differentiation (P = .05). Our combined analysis demonstrated that OCT4 ^low/NANOG ^low phenotype has frequently seen in colorectal cancer cases with no vascular invasion (P = .05).

Our observations indicated that higher expression of OCT4 and NANOG can confer malignant and aggressive behavior to CRC. Evaluation of the co-expression of these cancer stem cell markers can serve a new diagnostic and prognostic approach in CRC patients. These findings also suggested that simultaneous expression of OCT4 and NANOG can be considered as a therapeutic marker for targeted therapy of CRC, especially in advanced stages.

Exosomal release of microRNA-454 by breast cancer cells sustains biological properties of cancer stem cells via the PRRT2/Wnt axis in ovarian cancer

AIMS

Cancer-derived exosomes carrying tumor-derived molecules such as miRNAs and proteins related to various phenotypes have been detected in both the bloodstream and other biofluids of patients with different cancers. Thus, our main purpose here was to determine the role of the exosomal microRNA-454 (miR-454) derived by MDA-MB-231 in self-renewal of cancer stem cells (CSCs) in ovarian cancer (OC).

MATERIALS AND METHODS

Extraction of MDA-MB-231 cells-derived exosomes (231-derived exosomes) was conducted to treat CD44+/CD133+ SKOV3 and CoC1 cells to observe cell growth and stemness. Next, the differentially expressed miRNAs in SKOV3 cells after exosome treatment were filtered using microarray analysis. Subsequently, the cell viability was detected after reducing the exosomal miR-454 and the addition of a Wnt pathway inhibitor C59. Finally, the pro-tumorigenic function of exosomes on OC cells in vivo was investigated.

KEY FINDINGS

After co-culture with 231-derived exosomes, the stemness of CSCs were promoted. Subsequently, the reduction of exosomal miR-454 weakened the roles of exosomes on cell stemness. Proline-rich transmembrane protein 2 (PRRT2) was substantiated as a target gene of miR-454 in SKOV3 and CoC1 cells. C59 reversed the repressive role of exosomes in stemness of CSCs. When being evaluated in a mouse model, exosomal miR-454 led to an efficacious effect in suppressing the tumor weight and volume in vivo.

SIGNIFICANCE

Altogether, 231-derived exosomes carrying miR-454 disrupted the Wnt pathway by targeting PRRT2, thereby promoting CSC stemness in vitro and OC cell growth in vivo.

Lin28A Regulates Stem-like Properties of Ovarian Cancer Cells by Enriching RAN and HSBP1 mRNA and Up-regulating its Protein Expression

Ovarian cancer (OC) is one of the malignant tumors that seriously threaten women's health, with the highest mortality rate in gynecological malignancies. The prognosis of patients with advanced OC is still poor, and the 5-year survival rate is only 20-30%. Therefore, how to improve the early diagnosis rate and therapeutic effect are urgent for patients with OC. In this research, we found that Lin28A can promote the expression of stem cell marker molecules CD133, CD44, OCT4 and Nanog. We later confirmed that Lin28A can enrich the mRNA of ras-related nuclear protein (RAN) and heat shock factor binding protein 1 (HSBP1) through RIP assay, and that Lin28A can regulate their protein expression. We also identified that RAN and HSBP1 are highly expressed in OC tissues, and that they are significantly positively correlated with the expression of Lin28A and negatively correlated with the survival prognosis of OC patients. After stable knockdown of RAN or HSBP1 in OC cells with high expression of Lin28A, the expression of the stem cell marker molecules such as OCT4, CD44 and Nanog are reduced. And after knocking down of RAN or HSBP1 in Lin28A highly expressed OC cells, the survival and invasion of OC cells and tumor size of OC xenograft in nude mice were markedly inhibited and apoptosis was increased. Our data also showed that knock down of RAN or HSBP1 can inhibit the invasion ability of OC cells by decreasing the expression of N-cadherin, Vimentin and promoting the expression of E-cadherin. Meanwhile, knockdown of RAN or HSBP1 induced cell apoptosis by inhibiting the expression of PARP. Our results indicated that Lin28A could regulate the biological behaviors in OC cells through RAN/HSBP1. These findings suggest that Lin28A/RAN/HSBP1 can be used as a marker for diagnosis and prognosis of OC patients, and RAN/HSBP1 may be a potential new target for gene therapy of OC.

PTEN/AKT/mTOR signaling mediates anticancer effects of epigallocatechin‑3‑gallate in ovarian cancer

Epigallocatechin‑3‑gallate (EGCG), a polyphenol present in green tea, exhibits anticancer effects in various types of cancer. A number of studies have focused on the effects of EGCG on lung cancer, but not ovarian cancer. Previous reports have implicated that EGCG suppressed ovarian cancer cell proliferation and induced apoptosis, but its potential anticancer mechanisms and signaling pathways remain unclear. Thus, it is necessary to determine the anti‑ovarian cancer effects of EGCG and explore the underlying mechanisms. In the present study, EGCG exerted stronger proliferation inhibition on SKOV3 cells compared with A549 cells and induced apoptosis in SKOV3 cells, as well as upregulated PTEN expression and downregulated the expression of phosphoinositide‑dependent kinase‑1 (PDK1), phosphor (p)‑AKT and p‑mTOR. These effects were reversed by the PTEN inhibitor VO‑Ohpic trihydrate. The results of the mouse xenograft experiment demonstrated that 50 mg/kg EGCG exhibited increased tumor growth inhibition compared with 5 mg/kg paclitaxel. In addition, PTEN expression was upregulated, whereas the expression levels of PDK1, p‑AKT and p‑mTOR were downregulated in the EGCG treatment group compared with those in untreated mice in vivo. In conclusion, the results of the present study provided a new underlying mechanism of the effect of EGCG on ovarian cancer and may lead to the development of EGCG as a candidate drug for ovarian cancer therapy.

Understanding the Role of the Transcription Factor Sp1 in Ovarian Cancer: from Theory to Practice

Ovarian cancer (OC) is one of the deadliest cancers among women contributing to high risk of mortality, mainly owing to delayed detection. There is no specific biomarker for its detection in early stages. However, recent findings show that over-expression of specificity protein 1 (Sp1) is involved in many OC cases. The ubiquitous transcription of Sp1 apparently mediates the maintenance of normal and cancerous biological processes such as cell growth, differentiation, angiogenesis, apoptosis, cellular reprogramming and tumorigenesis. Sp1 exerts its effects on cellular genes containing putative GC-rich Sp1-binding site in their promoters. A better understanding of the mechanisms underlying Sp1 transcription factor (TF) regulation and functions in OC tumorigenesis could help identify novel prognostic markers, to target cancer stem cells (CSCs) by following cellular reprogramming and enable the development of novel therapies for future generations. In this review, we address the structure, function, and biology of Sp1 in normal and cancer cells, underpinning the involvement of Sp1 in OC tumorigenesis. In addition, we have highlighted the influence of Sp1 TF in cellular reprogramming of iPSCs and how it plays a role in controlling CSCs. This review highlights the drugs targeting Sp1 and their action on cancer cells. In conclusion, we predict that research in this direction will be highly beneficial for OC treatment, and chemotherapeutic drugs targeting Sp1 will emerge as a promising therapy for OC.