Cancer stem-like cells can be isolated with drug selection in human ovarian cancer cell line SKOV3

STAU1-mediated CNBP mRNA degradation by LINC00665 alters stem cell characteristics in ovarian cancer

BACKGROUND

To investigate the role of lncRNA LINC00665 in modulating ovarian cancer stemness and its influence on treatment resistance and cancer development.

METHODS

We isolated ovarian cancer stem cells (OCSCs) from the COC1 cell line using a combination of chemotherapeutic agents and growth factors, and verified their stemness through western blotting and immunofluorescence for stem cell markers. Employing bioinformatics, we identified lncRNAs associated with ovarian cancer, with a focus on LINC00665 and its interaction with the CNBP mRNA. In situ hybridization, immunohistochemistry, and qPCR were utilized to examine their expression and localization, alongside functional assays to determine the effects of LINC00665 on CNBP.

RESULTS

LINC00665 employs its Alu elements to interact with the 3'-UTR of CNBP mRNA, targeting it for degradation. This molecular crosstalk enhances stemness by promoting the STAU1-mediated decay of CNBP mRNA, thereby modulating the Wnt and Notch signaling cascades that are pivotal for maintaining CSC characteristics and driving tumor progression. These mechanistic insights were corroborated by a series of in vitro assays and validated in vivo using tumor xenograft models. Furthermore, we established a positive correlation between elevated CNBP levels and increased disease-free survival in patients with ovarian cancer, underscoring the prognostic value of CNBP in this context.

CONCLUSIONS

lncRNA LINC00665 enhances stemness in ovarian cancer by mediating the degradation of CNBP mRNA, thereby identifying LINC00665 as a potential therapeutic target to counteract drug resistance and tumor recurrence associated with CSCs.

Predicting Prognosis and Platinum Resistance in Ovarian Cancer: Role of Immunohistochemistry Biomarkers

Ovarian cancer is a lethal reproductive tumour affecting women worldwide. The advancement in presentation and occurrence of chemoresistance are the key factors for poor survival among ovarian cancer women. Surgical debulking was the mainstay of systemic treatment for ovarian cancer, which was followed by a successful start to platinum-based chemotherapy. However, most women develop platinum resistance and relapse within six months of receiving first-line treatment. Thus, there is a great need to identify biomarkers to predict platinum resistance before enrolment into chemotherapy, which would facilitate individualized targeted therapy for these subgroups of patients to ensure better survival and an improved quality of life and overall outcome. Harnessing the immune response through immunotherapy approaches has changed the treatment way for patients with cancer. The immune outline has emerged as a beneficial tool for recognizing predictive and prognostic biomarkers clinically. Studying the tumour microenvironment (TME) of ovarian cancer tissue may provide awareness of actionable targets for enhancing chemotherapy outcomes and quality of life. This review analyses the relevance of immunohistochemistry biomarkers as prognostic biomarkers in predicting chemotherapy resistance and improving the quality of life in ovarian cancer.

Enhanced biological activity of liposomal methylated resveratrol analog 3'-hydroxy-3,4,5,4'-tetramethoxystilbene (DMU-214) in 3D patient-derived ovarian cancer model

3′-hydroxy-3,4,5,4′-tetramethoxystilbene (DMU-214) belongs to methoxystilbenes family and is an active metabolite of 3,4,5,4′-tetramethoxystilbene (DMU-212). In several of our previous studies, the anti-apoptotic activity of DMU-214 was significantly higher than that of the parent compound, especially in ovarian cancer cells. Due to increased lipophilicity and limited solubility, methoxystilbenes require a solubilization strategy enabling DMU-214 administration to the aqueous environment. In this study, DMU-214-loaded liposomes were developed for the first time, and its antitumor activity was tested in the ovarian cancer model.

First, several liposomal formulations of DMU-214 were obtained by the thin lipid film hydration method followed by extrusion and then characterized. The diameter of the resulting vesicles was in the range of 118.0-155.5 nm, and samples presented monodisperse size distribution. The release of DMU-214 from the studied liposomes was governed by the contribution of two mechanisms, Fickian diffusion and liposome relaxation.

Subsequently, in vitro activity of DMU-214 in the form of a free compound or liposome-bound was studied, including commercial cell line SK-OV-3 and patient-derived ovarian cancer cells in monolayer and spheroid cell culture models. DMU-214 liposomal formulations were found to be more potent (had lower IC₅₀ values) than the free DMU-214 both in the monolayer and, more significantly, in both examined spheroid models. The above results, with particular emphasis on the patient-derived ovarian cancer model, indicate the importance of further development of liposomal DMU-214 as a potential anticancer formulation for ovarian cancer treatment.

Discrete stochastic models of SELEX: Aptamer capture probabilities and protocol optimization

Antibodies are important biomolecules that are often designed to recognize target antigens. However, they are expensive to produce and their relatively large size prevents their transport across lipid membranes. An alternative to antibodies is aptamers, short ([Formula: see text] bp) oligonucleotides (and amino acid sequences) with specific secondary and tertiary structures that govern their affinity to specific target molecules. Aptamers are typically generated via solid phase oligonucleotide synthesis before selection and amplification through Systematic Evolution of Ligands by EXponential enrichment (SELEX), a process based on competitive binding that enriches the population of certain strands while removing unwanted sequences, yielding aptamers with high specificity and affinity to a target molecule. Mathematical analyses of SELEX have been formulated in the mass action limit, which assumes large system sizes and/or high aptamer and target molecule concentrations. In this paper, we develop a fully discrete stochastic model of SELEX. While converging to a mass-action model in the large system-size limit, our stochastic model allows us to study statistical quantities when the system size is small, such as the probability of losing the best-binding aptamer during each round of selection. Specifically, we find that optimal SELEX protocols in the stochastic model differ from those predicted by a deterministic model.

Long-Term Glucose Restriction with or without β-Hydroxybutyrate Enrichment Distinctively Alters Epithelial-Mesenchymal Transition-Related Signalings in Ovarian Cancer Cells

The beneficial impacts of the ketogenic diet and metabolic reprograming were recently reported for ovarian cancer patients. In this study, the effects of glucose restriction with or without beta-hydroxybutyrate (bHB) enrichment were studied in drug-resistant CD133high A2780CP and CD133low SK-OV-3 ovarian cancer cells to scrutinize the impact of experimental ketosis on ATP production, epithelial to mesenchymal transition (EMT), and related signaling pathways including Wnt, Hippo, and Hedgehog. Cells were adapted and maintained for a month with restricted levels of glucose (250 mg/l) with or without the therapeutic concentration of bHB (5 mM). Quantitative PCR, Western blot analysis, flow cytometry, chemiluminescence, and wound healing assay were used in this study. Glucose restriction and bHB enrichment reduced the stemness marker and diminished In Vitro migration in both cell lines. Glucose restriction significantly reduced ATP levels in both cells, but bHB enrichment was partially compensated for the ATP levels solely in SK-OV-3 cells. Glucose restriction mainly inhibited the Wnt pathway in the CD133high A2780CP cells, but the Hedgehog pathway was the main target in CD133low SK-OV-3 cells. In Conclusion, Prior targeted evaluations of key genes' expression would help to predict the distinctive impacts of metabolic fuels and to optimize the efficacy of ketogenic diets.

Natural Compounds Targeting Cancer Stem Cells: A Promising Resource for Chemotherapy

BACKGROUND

Cancer Stem Cells (CSCs) are the subpopulation of cancer cells which are directly involved in drug resistance, metastases to distant organ and cancer recurrence.

METHODS

A systematic literature search was conducted through various electronic databases including, Pubmed, Scopus, Google scholar using the keywords "cancer stem cells" and "natural compounds" in the present study. Articles published between 1999 and 2019 were reviewed. All the expositions concerning CSCs associated cancer pathogenesis and therapy resistance, as well as targeting these properties of CSCs by natural compounds were selected for the current study.

RESULTS

Natural compounds have always been thought as a rich source of biologically active principles, which target aberrantly activated signaling pathways and other modalities of CSCs, while tethering painful side effects commonly involved in the first-line and second-line chemo-radiotherapies. In this review, we have described the key signaling pathways activated in CSCs to maintain their survival and highlighted how natural compounds interrupt these signaling pathways to minimize therapy resistance, pathogenesis and cancer recurrence properties of CSCs, thereby providing useful strategies to treat cancer or aid in cancer therapy improvement. Like normal stem cells, CSCs rely on different signaling pathways and other properties for their maintenance. Therefore, the success of cancer treatment depends on the development of proper anti-neoplastic drugs capable of intercepting those signaling pathways as well as other properties of CSCs in order to eradicate this evasive subpopulation of cancer cells.

CONCLUSION

Compounds of natural origin might act as an outstanding source to design novel therapies against cancer stem cells.

Roles of microRNAs in Ovarian Cancer Tumorigenesis: Two Decades Later, What Have We Learned?

Ovarian cancer is one of the top gynecological malignancies that cause deaths among females in the United States. At the molecular level, significant progress has been made in our understanding of ovarian cancer development and progression. MicroRNAs (miRNAs) are short, single-stranded, highly conserved non-coding RNA molecules (19–25 nucleotides) that negatively regulate target genes post-transcriptionally. Over the last two decades, mounting evidence has demonstrated the aberrant expression of miRNAs in different human malignancies, including ovarian carcinomas. Deregulated miRNAs can have profound impacts on various cancer hallmarks by repressing tumor suppressor genes. This review will discuss up-to-date knowledge of how the aberrant expression of miRNAs and their targeted genes drives ovarian cancer initiation, proliferation, survival, and resistance to chemotherapies. Understanding the mechanisms by which these miRNAs affect these hallmarks should allow the development of novel therapeutic strategies to treat these lethal malignancies.

Cancer Stem Cells as a Potential Target to Overcome Multidrug Resistance

Multidrug resistance (MDR), which is a significant impediment to the success of cancer chemotherapy, is attributable to various defensive mechanisms in cancer. Initially, overexpression of ATP-binding cassette (ABC) transporters such as P-glycoprotein (P-gp) was considered the most important mechanism for drug resistance; hence, many investigators for a long time focused on the development of specific ABC transporter inhibitors. However, to date their efforts have failed to develop a clinically applicable drug, leaving only a number of problems. The concept of cancer stem cells (CSCs) has provided new directions for both cancer and MDR research. MDR is known to be one of the most important features of CSCs and thus plays a crucial role in cancer recurrence and exacerbation. Therefore, in recent years, research targeting CSCs has been increasing rapidly in search of an effective cancer treatment. Here, we review the drugs that have been studied and developed to overcome MDR and CSCs, and discuss the limitations and future perspectives.

An ovarian spheroid based tumor model that represents vascularized tumors and enables the investigation of nanomedicine therapeutics

The failure of cancer therapies in clinical settings is often attributed to the lack of a relevant tumor model and pathological heterogeneity across tumor types in the clinic. The objective of this study was to develop a robust in vivo tumor model that better represents clinical tumors for the evaluation of anti-cancer therapies. We successfully developed a simple mouse tumor model based on 3D cell culture by injecting a single spheroid and compared it to a tumor model routinely used by injecting cell suspension from 2D monolayer cell culture. We further characterized both tumors with cellular markers for the presence of myofibroblasts, pericytes, endothelial cells and extracellular matrix to understand the role of the tumor microenvironment. We further investigated the effect of chemotherapy (doxorubicin), nanomedicine (Doxil®), biological therapy (Avastin®) and their combination. Our results showed that the substantial blood vasculature in the 3D spheroid model enhances the delivery of Doxil® by 2.5-fold as compared to the 2D model. Taken together, our data suggest that the 3D tumors created by simple subcutaneous spheroid injection represents a robust and more vascular murine tumor model which is a clinically relevant platform to test anti-cancer therapy in solid tumors.

Sox2 promotes expression of the ST6Gal-I glycosyltransferase in ovarian cancer cells

Background

The ST6Gal-I glycosyltransferase, which adds α2–6-linked sialic acids to N-glycosylated proteins is upregulated in a wide range of malignancies including ovarian cancer. Prior studies have shown that ST6Gal-I-mediated sialylation of select surface receptors remodels intracellular signaling to impart cancer stem cell (CSC) characteristics. However, the mechanisms that contribute to ST6Gal-I expression in stem-like cancer cells are poorly understood.

Results

Herein, we identify the master stem cell transcription factor, Sox2, as a novel regulator of ST6Gal-I expression. Interestingly, SOX2 and ST6GAL1 are located within the same tumor-associated amplicon, 3q26, and these two genes exhibit coordinate gains in copy number across multiple cancers including ~ 25% of ovarian serious adenocarcinomas. In conjunction with genetic co-amplification, our studies suggest that Sox2 directly binds the ST6GAL1 promoter to drive transcription. ST6Gal-I expression is directed by at least four distinct promoters, and we identified the P3 promoter as the predominant promoter utilized by ovarian cancer cells. Chromatin Immunoprecipitation (ChIP) assays revealed that Sox2 binds regions proximal to the P3 promoter. To confirm that Sox2 regulates ST6Gal-I expression, Sox2 was either overexpressed or knocked-down in various ovarian cancer cell lines. Sox2 overexpression induced an increase in ST6Gal-I mRNA and protein, as well as surface α2–6 sialylation, whereas Sox2 knock-down suppressed levels of ST6Gal-I mRNA, protein and surface α2–6 sialylation.

Conclusions

These data suggest a process whereby SOX2 and ST6GAL1 are coordinately amplified in cancer cells, with the Sox2 protein then binding the ST6GAL1 promoter to further augment ST6Gal-I expression. Our collective results provide new insight into mechanisms that upregulate ST6Gal-I expression in ovarian cancer cells, and also point to the possibility that some of the CSC characteristics commonly attributed to Sox2 may, in part, be mediated through the sialyltransferase activity of ST6Gal-I.

SOX2 in development and cancer biology

The transcription factor SOX2 is essential for embryonic development and plays a crucial role in maintaining the stemness of embryonic cells and various adult stem cell populations. On the other hand, dysregulation of SOX2 expression is associated with a multitude of cancer types and it has been shown that SOX2 positively affects cancer cell traits such as the capacity to proliferate, migrate, invade and metastasize. Moreover, there is growing evidence that SOX2 mediates resistance towards established cancer therapies and that it is expressed in cancer stem cells. These findings indicate that studying the role of SOX2 in the context of cancer progression could lead to the development of new therapeutic options. In this review, the current knowledge about the role of SOX2 in development, maintenance of stemness, cancer progression and the resistance towards cancer therapies is summarized.

Epithelial ovarian cancer stem‑like cells are resistant to the cellular lysis of cytokine‑induced killer cells via HIF1A‑mediated downregulation of ICAM‑1

Epithelial ovarian cancer (EOC) is the most lethal of all gynecologic tumors. Cancer spheroid culture is a widely used model to study cancer stem cells. Previous studies have demonstrated the effectiveness of cytokine‑induced killer (CIK) cell‑based therapies against cancer and cancer stem cells. However, it is not clear how EOC spheroid cells respond to CIK‑mediated cellular lysis, and the mechanisms involved have never been reported before. A flow cytometry‑based method was used to evaluate the anti‑cancer effects of CIK cells against adherent A2780 cells and A2780 spheroids. To demonstrate the association between hypoxia inducible factor‑1α (HIF1A) and intercellular adhesion molecule‑1 (ICAM‑1), two HIF1A short hairpin RNA (shRNA) stable transfected cell lines were established. Furthermore, the protein expression levels of hypoxia/HIF1A‑associated signaling pathways were evaluated, including transforming growth factor‑β1 (TGF‑β1)/mothers against decapentaplegic homologs (SMADs) and nuclear factor‑κB (NF‑κB) signaling pathways, comparing A2780 adherent cells and cancer spheroids. Flow cytometry revealed that A2780 spheroid cells were more resistant to CIK‑mediated cellular lysis, which was partially reversed by an anti‑ICAM‑1 antibody. HIF1A was significantly upregulated in A2780 spheroids compared with adherent cells. Using HIF1A shRNA stable transfected cell lines and cobalt chloride, it was revealed that hypoxia/HIF1A contributed to downregulation of ICAM‑1 in A2780 spheroid cells and adherent cells. Furthermore, hypoxia/HIF1A‑associated signaling pathways, TGF‑β1/SMADs and NF‑κB, were activated in A2780 spheroid cells by using western blotting. The findings indicate that EOC stem‑like cells resist the CIK‑mediated cellular lysis via HIF1A‑mediated downregulation of ICAM‑1, which may be instructive for optimizing and enhancing CIK‑based therapies.

A new strategy for enhancing antitumor immune response using dendritic cells loaded with chemo-resistant cancer stem-like cells in experimental mice model

BACKGROUND AND AIM

Cancer stem cells (CSCs) are rare cell population present in the tumor bulk that are thought to be the reason for treatment failure following chemotherapy in terms of their intrinsic chemo-resistance. Our study aimed to develop an effective therapeutic strategy to target chemo-resistant cancer stem - like cells population in solid Ehrlich carcinoma (SEC) mice model using dendritic cells (DCs) loaded with enriched tumor cells lysate bearing CSC-like phenotype as a vaccine.

MATERIALS AND METHODS

Ehrlich carcinoma cell line was exposed to different concentrations of cisplatin, doxorubicin, or paclitaxel. Drug treatment that resulted in drug surviving cells with the highest expression of CSCs markers (CD44⁺/CD24^-) was selected to obtain enriched cell cultures with resistant CSCs population. Dendritic cells were isolated from mice bone marrow, pulsed with enriched CSC lysate, analyzed and identified (CD11c, CD83 and CD86). SEC-bearing mice were treated with loaded or unloaded DCs either as single treatment or in combination with repeated low doses of cisplatin. IFN- γ serum level and p53gene expression in tumor tissues were determined by ELISA and real-time PCR, respectively.

RESULTS AND CONCLUSION

The results revealed that vaccination with CSC loaded DCs significantly reduced tumor size, prolonged survival rate, increased IFN-γ serum levels, and upregulated p53gene expression in SEC bearing mice. These findings were more evident and significant in the group co-treated with CSC-DC and cisplatin rather than other treated groups. This study opens the field for combining CSC-targeted immunotherapy with repeated low doses chemotherapy as an effective strategy to improve anticancer immune responses.

Histone methyltransferase NSD2 regulates apoptosis and chemosensitivity in osteosarcoma

Osteosarcoma (OS) is a primary malignant bone tumour. However, the genetic basis for the pathogenesis of OS remains elusive. In this study, we uncovered the role of the histone methyltransferase NSD2 in regulating tumourigenesis and chemosensitivity in OS. We show that NSD2 knockdown leads to increased apoptosis in OS cells in vitro and in vivo. Additionally, NSD2 knockdown significantly enhances the efficacy of cisplatin against OS cells and accordingly inhibits properties associated with cancer stem cells (CSCs). Furthermore, RNA sequencing (RNAseq) and Gene Ontology (GO) analysis revealed that NSD2 promotes transcription of genes associated with negative regulation of apoptotic signalling pathways and CSC properties. The results of chromatin immunoprecipitation quantitative polymerase chain reaction (ChIP-qPCR) assays indicated that NSD2 knockdown leads to decreased H3K36me2 modification at BCL2 and SOX2 loci, thus inhibiting the transcription of these two genes that are closely correlated with apoptosis, CSC properties and chemosensitivity in OS cells. Pathway analysis demonstrated that the ERK and AKT pathways mediate the regulation of OS progression and chemosensitivity by NSD2. Overall, our study is the first to uncover the function of NSD2 in OS chemosensitivity. NSD2 regulates the expression of the apoptosis regulatory proteins BCL2 and SOX2 through the ERK and AKT pathways. Our results suggest that NSD2 is a new target for combined chemotherapy and is a prognostic factor for OS.

BRCA1 affects the resistance and stemness of SKOV3-derived ovarian cancer stem cells by regulating autophagy

Breast cancer 1 (BRCA1) and autophagy both play a significant role in drug resistance. However, little is known about the dynamic cross talk between BRCA1 and autophagy in the regulation of drug sensitivity. Here, we investigated the drug resistance-associated regulation of BRCA1 in epithelial ovarian cancer stem cells (EOCSCs). The results indicated that BRCA1 could regulate drug resistance in EOCSCs. Autophagy played a significant role in the stemness maintenance and was a key mechanism underlying the survival against chemotherapy in EOCSCs. Further investigation found that BRCA1 could regulate drug resistance of EOCSCs through autophagy. Meanwhile, changes in the level of autophagy provided feedback regarding the expression of BRCA1. Inhibition of autophagy activity could effectively reduce the resistance of EOCSCs caused by BRCA1. In addition, BRCA1 was able to regulate cellular apoptosis and cell cycle progression under the action of cisplatin through autophagy, indirectly affecting the drug sensitivity of EOCSCs. The present results highlight a novel relationship between BRCA1 and autophagy, which may provide insight into the etiology of BRCA1-associated ovarian cancer, and improve our understanding of resistance mechanisms in ovarian cancer.

A spermine-conjugated lipophilic Pt(iv) prodrug designed to eliminate cancer stem cells in ovarian cancer

A spermine-conjugated lipophilic Pt(iv) prodrug is designed to induce mitochondrial damage and eliminate ovarian cancer stem cells.

Ovarian cancer stem cell: A potential therapeutic target for overcoming multidrug resistance

The cancer stem cell (CSC) model encompasses an advantageous paradigm that in recent decades provides a better elucidation for many important biological aspects of cancer initiation, progression, metastasis, and, more important, development of multidrug resistance (MDR). Such several other hematological malignancies and solid tumors and the identification and isolation of ovarian cancer stem cells (OV-CSCs) show that ovarian cancer also follows this hierarchical model. Gaining a better insight into CSC-mediated resistance holds promise for improving current ovarian cancer therapies and prolonging the survival of recurrent ovarian cancer patients in the future. Therefore, in this review, we will discuss some important mechanisms by which CSCs can escape chemotherapy, and then review the recent and growing body of evidence that supports the contribution of CSCs to MDR in ovarian cancer.

Can Stemness and Chemoresistance Be Therapeutically Targeted via Signaling Pathways in Ovarian Cancer?

Ovarian cancer is the most lethal gynecological malignancy. Poor overall survival, particularly for patients with high grade serous (HGS) ovarian cancer, is often attributed to late stage at diagnosis and relapse following chemotherapy. HGS ovarian cancer is a heterogenous disease in that few genes are consistently mutated between patients. Additionally, HGS ovarian cancer is characterized by high genomic instability. For these reasons, personalized approaches may be necessary for effective treatment and cure. Understanding the molecular mechanisms that contribute to tumor metastasis and chemoresistance are essential to improve survival rates. One favored model for tumor metastasis and chemoresistance is the cancer stem cell (CSC) model. CSCs are cells with enhanced self-renewal properties that are enriched following chemotherapy. Elimination of this cell population is thought to be a mechanism to increase therapeutic response. Therefore, accurate identification of stem cell populations that are most clinically relevant is necessary. While many CSC identifiers (ALDH, OCT4, CD133, and side population) have been established, it is still not clear which population(s) will be most beneficial to target in patients. Therefore, there is a critical need to characterize CSCs with reliable markers and find their weaknesses that will make the CSCs amenable to therapy. Many signaling pathways are implicated for their roles in CSC initiation and maintenance. Therapeutically targeting pathways needed for CSC initiation or maintenance may be an effective way of treating HGS ovarian cancer patients. In conclusion, the prognosis for HGS ovarian cancer may be improved by combining CSC phenotyping with targeted therapies for pathways involved in CSC maintenance.

The dark side of SOX2: cancer - a comprehensive overview

The pluripotency-associated transcription factor SOX2 is essential during mammalian embryogenesis and later in life, but SOX2 expression can also be highly detrimental. Over the past 10 years, SOX2 has been shown to be expressed in at least 25 different cancers. This review provides a comprehensive overview of the roles of SOX2 in cancer and focuses on two broad topics. The first delves into the expression and function of SOX2 in cancer focusing on the connection between SOX2 levels and tumor grade as well as patient survival. As part of this discussion, we address the developing connection between SOX2 expression and tumor drug resistance. We also call attention to an under-appreciated property of SOX2, its levels in actively proliferating tumor cells appear to be optimized to maximize tumor growth - too little or too much SOX2 dramatically alters tumor growth. The second topic of this review focuses on the exquisite array of molecular mechanisms that control the expression and transcriptional activity of SOX2. In addition to its complex regulation at the transcriptional level, SOX2 expression and activity are controlled carefully by microRNAs, long non-coding RNAs, and post-translational modifications. In the Conclusion and Future Perspectives section, we point out that there are still important unanswered questions. Addressing these questions is expected to lead to new insights into the functions of SOX2 in cancer, which will help design novels strategies for more effectively treating some of the most deadly cancers.

Hypoxia-NOTCH1-SOX2 signaling is important for maintaining cancer stem cells in ovarian cancer

Hypoxia and NOTCH signaling have been reported to be associated with the self-renewal and drug resistance of cancer stem cells (CSCs). However, the molecular mechanisms by which hypoxia and NOTCH signaling stimulate the self-renewal and drug resistance of ovarian CSCs are poorly understood. In the present study, we identified SOX2 as a key transcription factor for CSC-like characteristics in the downstream of hypoxia-induced NOTCH signaling in epithelial ovarian cancer cells. Hypoxic treatment or overexpression of intracellular domain of NOTCH1 (NICD1) in ovarian cancer cells increased sphere formation, drug resistance, and expression of CSC-associated genes such as SOX2, ALDH, and ABC transporters. Hypoxic treatment increased the expression of NICD1, and hypoxic treatment or NICD1 overexpression increased SOX2 promoter activity, which was inhibited by deletion of HIF-1 or CSL binding sites. Furthermore, DAPT treatment decreased the effect of hypoxic treatment, and SOX2 knockdown decreased the effect of hypoxic treatment and NICD overexpression on sphere formation and drug resistance in established ovarian cancer cell lines and primary ovarian cancer cells. These results suggest that hypoxia-NOTCH1-SOX2 signaling axis is important for activation of ovarian CSCs, which may provide a novel opportunity for developing therapeutics to eradicate CSCs in ovarian cancer patients.

Dietary compound proanthocyanidins from Chinese bayberry (Myrica rubra Sieb. et Zucc.) leaves attenuate chemotherapy-resistant ovarian cancer stem cell traits via targeting the Wnt/β-catenin signaling pathway and inducing G1 cell cycle arrest

Cancer stem cells (CSCs) represent a small population of cancer cells characterized by self-renewal ability, tumorigenesis and drug resistance. Ovarian cancer is one of the leading causes of death related to the female reproductive system in Western countries and has been evaluated as a type of CSC-related cancer in recent years. Natural products have attracted great attention in cancer treatment in recent years due to drug resistance and a high relapse rate of ovarian cancer. Chinese bayberry leaf proanthocyanidins (BLPs) contain epigallocatechin-3-O-gallate as their terminal and major extension units, which is quite unusual in the plant kingdom. BLPs showed strong antioxidant and antiproliferative abilities in previous studies. In the present study, chemotherapy-resistant OVCAR-3 spheroid (SP) cells were obtained by sphere culturing and exhibited CSC-like properties by showing a higher ALDH+ population and higher expression of stemness-related proteins. BLPs exhibited inhibitory effects on the growth and CSC characteristics of OVCAR-3 SP cells by showing decreased cell viability, sphere and colony formation ability, ALDH+ population and expression of stemness-related proteins. BLPs also targeted the Wnt/β-catenin pathway by reducing the expression of β-catenin, cyclin D1 and c-Myc and thus inhibited the self-renewal ability of OVCAR-3 SP cells. Furthermore, BLPs also induced G1 cell cycle arrest in OVCAR-3 SP cells. Taken together, these findings suggested that BLPs may be an important agent in the development of therapeutics for ovarian cancer patients.

SOX2 functions as a molecular rheostat to control the growth, tumorigenicity and drug responses of pancreatic ductal adenocarcinoma cells

Pancreatic ductal adenocarcinoma (PDAC) is a highly deadly malignancy. Expression of the stem cell transcription factor SOX2 increases during progression of PDAC. Knockdown of SOX2 in PDAC cell lines decreases growth in vitro; whereas, stable overexpression of SOX2 in one PDAC cell line reportedly increases growth in vitro. Here, we reexamined the role of SOX2 in PDAC cells, because inducible SOX2 overexpression in other tumor cell types inhibits growth. In this study, four PDAC cell lines were engineered for inducible overexpression of SOX2 or inducible knockdown of SOX2. Remarkably, inducible overexpression of SOX2 in PDAC cells inhibits growth in vitro and reduces tumorigenicity. Additionally, inducible knockdown of SOX2 in PDAC cells reduces growth in vitro and in vivo. Thus, growth and tumorigenicity of PDAC cells is highly dependent on the expression of optimal levels of SOX2 – a hallmark of molecular rheostats. We also determined that SOX2 alters the responses of PDAC cells to drugs used in PDAC clinical trials. Increasing SOX2 reduces growth inhibition mediated by MEK and AKT inhibitors; whereas knockdown of SOX2 further reduces growth when PDAC cells are treated with these inhibitors. Thus, targeting SOX2, or its mode of action, could improve the treatment of PDAC.

Chemical Proteomic Approaches Targeting Cancer Stem Cells: A Review of Current Literature

Cancer stem cells (CSCs) have been proposed as central drivers of tumor initiation, progression, recurrence, and therapeutic resistance. Therefore, identifying stem-like cells within cancers and understanding their properties is crucial for the development of effective anticancer therapies. Recently, chemical proteomics has become a powerful tool to efficiently determine protein networks responsible for CSC pathophysiology and comprehensively elucidate molecular mechanisms of drug action against CSCs. This review provides an overview of major methodologies utilized in chemical proteomic approaches. In addition, recent successful chemical proteomic applications targeting CSCs are highlighted. Future direction of potential CSC research by integrating chemical genomic and proteomic data obtained from a single biological sample of CSCs are also suggested in this review.

A multi-stage process including transient polyploidization and EMT precedes the emergence of chemoresistent ovarian carcinoma cells with a dedifferentiated and pro-inflammatory secretory phenotype

DNA-damaging drugs induce a plethora of molecular and cellular alterations in tumor cells, but their interrelationship is largely obscure. Here, we show that carboplatin treatment of human ovarian carcinoma SKOV3 cells triggers an ordered sequence of events, which precedes the emergence of mitotic chemoresistant cells. The initial phase of cell death after initiation of carboplatin treatment is followed around day 14 by the emergence of a mixed cell population consisting of cycling, cell cycle-arrested and senescent cells. At this stage, giant cells make up >80% of the cell population, p21 (CDKN1A) in strongly induced, and cell numbers remain nearly static. Subsequently, cell death decreases, p21 expression drops to a low level and cell divisions increase, including regular mitoses of giant cells and depolyploidization by multi-daughter divisions. These events are accompanied by the upregulation of stemness markers and a pro-inflammatory secretory phenotype, peaking after approximately 14 days of treatment. At the same time the cells initiate epithelial to mesenchymal transition, which over the subsequent weeks continuously increases, concomitantly with the emergence of highly proliferative, migratory, dedifferentiated, pro-inflammatory and chemoresistant cells (SKOV3-R). These cells are anchorage-independent and grow in a 3D collagen matrix, while cells on day 14 do not survive under these conditions, indicating that SKOV3-R cells were generated thereafter by the multi-stage process described above. This process was essentially recapitulated with the ovarian carcinoma cell line IGROV-1. Our observations suggest that transitory cells characterized by polyploidy, features of stemness and a pro-inflammatory secretory phenotype contribute to the acquisition of chemoresistance.

Cisplatin Resistant Spheroids Model Clinically Relevant Survival Mechanisms in Ovarian Tumors

The majority of ovarian tumors eventually recur in a drug resistant form. Using cisplatin sensitive and resistant cell lines assembled into 3D spheroids we profiled gene expression and identified candidate mechanisms and biological pathways associated with cisplatin resistance. OVCAR-8 human ovarian carcinoma cells were exposed to sub-lethal concentrations of cisplatin to create a matched cisplatin-resistant cell line, OVCAR-8R. Genome-wide gene expression profiling of sensitive and resistant ovarian cancer spheroids identified 3,331 significantly differentially expressed probesets coding for 3,139 distinct protein-coding genes (Fc >2, FDR < 0.05) (S2 Table). Despite significant expression changes in some transporters including MDR1, cisplatin resistance was not associated with differences in intracellular cisplatin concentration. Cisplatin resistant cells were significantly enriched for a mesenchymal gene expression signature. OVCAR-8R resistance derived gene sets were significantly more biased to patients with shorter survival. From the most differentially expressed genes, we derived a 17-gene expression signature that identifies ovarian cancer patients with shorter overall survival in three independent datasets. We propose that the use of cisplatin resistant cell lines in 3D spheroid models is a viable approach to gain insight into resistance mechanisms relevant to ovarian tumors in patients. Our data support the emerging concept that ovarian cancers can acquire drug resistance through an epithelial-to-mesenchymal transition.

Low-dose cisplatin-induced CXCR4 expression promotes proliferation of ovarian cancer stem-like cells

Chemoresistance blocks the efficient treatment of epithelial ovarian cancer, which is the most lethal of all gynecological cancers. Cancer stem cells are believed to be at least partially responsible for the development of chemoresistance. In this study, the effect of cisplatin (CDP) on the enrichment and proliferation of cancer stem-like cells (CSLCs) was investigated, and the underlying mechanisms of action were elucidated. An in vitro anchor-free system was employed to enrich CSLCs from the SKOV3 human epithelial ovarian cancer cell line. Our results showed that treatment with low concentrations of CDP resulted in better-enriched CSLCs, with higher proliferative activities. Low dose of CDP was found to induce the expression of chemokine (C-X-C motif) receptor 4 (CXCR4), which is an important stemness marker in cancer stem cells as well as a promising therapeutic target for ovarian cancer treatment. Results also showed that overexpressed CXCR4 generated chemoresistance. Based on these results, it may be concluded that, at low concentrations, CDP itself contributes to the development of drug resistance. This finding provides novel insight into the mechanisms underlying chemoresistance and has significant therapeutic implications for epithelial ovarian cancer treatment.

An overview of new biomolecular pathways in pathogen-related cancers

Cancer molecular pathways are combinations of metabolic processes deregulated in neoplastic cells. Besides pathways specific to tissues from which cancers originate, common neoplastic traits are present among most tumors. Hanahan and Weinberg have described the most critical 'hallmarks' shared by many cancer types. In recent years, cancer stem cell specific properties and pathways have also been identified. Other altered pathways are peculiar of cancer type and cancer stage, even in different cancer stem cell types. In pathogen-related tumors, the alteration of inflammatory and immunologic response along with impairment of cell cycle control represents key molecular events of tumor progression. This article summarizes the recent discoveries of new altered pathways in cancer and their importance in cancer diagnosis and tailored therapies.

MiR-548c impairs migration and invasion of endometrial and ovarian cancer cells via downregulation of Twist

BACKGROUND

MicroRNAs (miRNAs) are a class of small non-coding RNAs, which post-transcriptionally repress the expression of genes involved in cancer initiation and progression. Although some miRNAs that target many signaling pathways (also called universe miRNAs) are supposed to play a global role in diverse human tumors, their regulatory functions in gynecological cancers remain largely unknown. We investigated the biological role and underlying mechanism of miR-548c (one universe miRNA) in endometrial and ovarian cancer.

METHODS

The effects of miR-548c overexpression on cell proliferation, migration and invasion were studied in endometrial and ovarian cancer cells. TWIST1 (Twist) was identified as a direct miR-548c target by western blot analysis and luciferase activity assay. The expression of miR-548c and Twist were examined by qRT-PCR in endometrial and ovarian cancer tissues.

RESULTS

Here, we report that miR-548c is down-regulated in endometrial and ovarian cancer tissues when compared to normal tissues, and our meta-analysis reveal that decreased miR-548c expression correlates with poor prognosis in endometrial cancer patients. We show that in endometrial and ovarian cancer cells, ectopic expression of miR-548c significantly inhibits whereas knockdown of miR-548c dramatically induces cancer cell proliferation, migration and invasion. By using luciferase reporter assay, we demonstrate that Twist, a known oncogene in endometrial and ovarian cancers, is a direct target of miR-548c. Furthermore, the expression of Twist partially abrogates the tumor suppressive effects of miR-548c on cell migration and invasion.

CONCLUSION

These findings suggest that miR-548c directly downregulates Twist, and provide a novel mechanism for Twist upregulation in both endometrial and ovarian cancers. The use of miR-548c may hold therapeutic potential for the treatment of Twist-overexpressing tumors.

Epithelial ovarian cancer stem-like cells expressing α-gal epitopes increase the immunogenicity of tumor associated antigens

Background

As ovarian cancer stem cells (CSCs) are responsible for tumor initiation, invasion, metastasis, and chemo-resistance, new stratagems that selectively target ovarian CSCs are critically significant. Our previous work have demonstrated that ovarian cancer spheroid cells are tumorigenic and chemo-resistant, and have the properties of ovarian CSCs. Herein, we hypothesized that expressing α-gal epitopes on ovarian spheroid cells may help eliminate CSCs and improve the outcome of therapeutic intervention for ovarian cancer patients.

Methods

Lentivirus-mediated transfer of a pig α(1,3)galactosyltransferase [α1,3GT] enzyme gene into human ovarian cell line SKOV3 cells formed α-gal epitope-expressing cells (SKOV3-gal cells), and then these cells were maintained in a serum-free culture system to form SKOV3-gal spheroid cells. Efficacy of this cell vaccine was demonstrated in α1,3GT knockout mice (α1,3GT KO mice).

Results

The antibody titers to α-gal epitopes measured by ELISA were significantly increased in α1,3GT KO mice after immunization with SKOV3-gal spheroid cells. Furthermore, compared with the non-immunized KO mice, the SKOV3 tumors grafted under renal capsules of KO mice immunized with SKOV3-gal spheroid cells grew slower and began to shrink on day 12. Western blot analysis also showed that immunized KO mice can produce effective antibody against certain tumor associated antigens (TAAs) derived from both SKOV3 cells and SKOV3 spheroid cells. The TAAs were further investigated by mass spectrometry and RNA interference (RNAi) technology. The results suggested that antibodies responding to protein c-erbB-2 may be raised in the sera of the mice after immunization with SKOV3-gal spheroid cells. Ultimately, vaccination with SKOV3-gal spheroid cells induced more CD3 + CD4 + T cells in the spleen of immunized mice than non-immunized KO mice.

Conclusions

The results suggest that vaccination using ovarian cancer stem-like cells engineered to express α-gal epitopes may be a novel strategy for treatment of ovarian cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1973-7) contains supplementary material, which is available to authorized users.

The emerging roles of Oct4 in tumor-initiating cells

Octamer-binding transcription factor 4 (Oct4), a homeodomain transcription factor, is well established as a master factor controlling the self-renewal and pluripotency of pluripotent stem cells. Also, a large body of research has documented the detection of Oct4 in tumor cells and tissues and has indicated its enrichment in a subpopulation of undifferentiated tumor-initiating cells (TICs) that critically account for tumor initiation, metastasis, and resistance to anticancer therapies. There is circumstantial evidence for low-level expression of Oct4 in cancer cells and TICs, and the participation of Oct4 in various TIC functions such as its self-renewal and survival, epithelial-mesenchymal transition (EMT) and metastasis, and drug resistance development is implicated from considerable Oct4 knockdown and overexpression-based studies. In a few studies, efforts have been made to identify Oct4 target genes in TICs of different sources. Based on such information, Oct4 in TICs appears to act via mechanisms quite distinct from those in pluripotent stem cells, and a main challenge for future studies is to unravel the molecular mechanisms of action of Oct4, particularly to address the question on how such low levels of Oct4 may exert its functions in TICs. Acquiring cells from their native microenvironment that are of high enough quantity and purity is the key to reliably analyze Oct4 functions and its target genes in TICs, and the information gained may greatly facilitate targeting and eradicating those cells.

Significance of ATP-binding cassette transporter proteins in multidrug resistance of head and neck squamous cell carcinoma

According to the cancer stem cell theory, a small subpopulation of cancer cells, known as cancer stem cells (CSCs), exist that are self-renewing and are involved in tumor invasion, metastasis and recurrence. A number of studies have reported that certain cancer cells are able to efflux the Hoechst 33342 dye. These cells are termed side population (SP) cells and share characteristic features of CSCs. The results of the present study revealed that 2.7% of primary head and neck squamous cell carcinoma (HNSCC) cells were SP cells. This was reduced to 0.7% following treatment with verapamil. The immunofluorescence and reverse transcription polymerase chain reaction analysis revealed that SP cells have an enhanced expression of the ATP-binding cassette (ABC) transporter protein ABC subfamily G, member 2 (ABCG2), which has been identified to be actively involved in drug exclusion. Similarly, the mRNA level of the oncogene B lymphoma Mo-MLV insertion region-1 and the stem cell surface proteins nestin and octamer-binding transcription factor-4 were highly expressed in the SP cells compared with the non-SP cells. In addition, it was demonstrated that HNSCC SP cells exhibited increased proliferation and were highly resistant to multiple drugs. These findings suggest that the presence of CSCs, such as SP cells, may be responsible for chemotherapy failure and tumor relapse in patients with HNSCC. Therefore, the identification of a novel therapeutic drug that could effectively target CSCs may help to eradicate refractory tumors.

Targeting Aggressive Cancer Stem Cells in Glioblastoma

Glioblastoma (GBM) is the most common and fatal type of primary brain tumor. Gliosarcoma (GSM) is a rarer and more aggressive variant of GBM that has recently been considered a potentially different disease. Current clinical treatment for both GBM and GSM includes maximal surgical resection followed by post-operative radiotherapy and concomitant and adjuvant chemotherapy. Despite recent advances in treating other solid tumors, treatment for GBM and GSM still remains palliative, with a very poor prognosis and a median survival rate of 12–15 months. Treatment failure is a result of a number of causes, including resistance to radiotherapy and chemotherapy. Recent research has applied the cancer stem cells theory of carcinogenesis to these tumors, suggesting the existence of a small subpopulation of glioma stem-like cells (GSCs) within these tumors. GSCs are thought to contribute to tumor progression, treatment resistance, and tumor recapitulation post-treatment and have become the focus of novel therapy strategies. Their isolation and investigation suggest that GSCs share critical signaling pathways with normal embryonic and somatic stem cells, but with distinct alterations. Research must focus on identifying these variations as they may present novel therapeutic targets. Targeting pluripotency transcription factors, SOX2, OCT4, and Nanog homeobox, demonstrates promising therapeutic potential that if applied in isolation or together with current treatments may improve overall survival, reduce tumor relapse, and achieve a cure for these patients.

ARID3B increases ovarian tumor burden and is associated with a cancer stem cell gene signature

Ovarian cancer is the most deadly gynecological malignancy since most patients have metastatic disease at the time of diagnosis. Therefore, identification of critical pathways that contribute to ovarian cancer progression is necessary to yield novel therapeutic targets. Recently we reported that the DNA binding protein ARID3B is overexpressed in human ovarian tumors. To determine if ARID3B has oncogenic functions in vivo, ovarian cancer cell lines stably expressing ARID3B were injected intraperitoneally into nude mice. Overexpression of ARID3B increased tumor burden and decreased survival. To assess how ARID3B contributes to the increased tumor growth in vivo, we identified ARID3B induced genes in tumor ascites cells. ARID3B induced expression of genes associated with metastasis and cancer stem cells (CD44, LGR5, PROM1 (CD133), and Notch2). Moreover, ARID3B increased the number of CD133+ (a cancer stem cell marker) cells compared to control cells. The increase in CD133+ cells resulting from ARID3B expression was accompanied by enhanced paclitaxel resistance. Our data demonstrate that ARID3B boosts production CD133+ cells and increases ovarian cancer progression in vivo.

Nestin as a marker of cancer stem cells

The crucial role of cancer stem cells (CSCs) in the pathology of malignant diseases has been extensively studied during the last decade. Nestin, a class VI intermediate filament protein, was originally detected in neural stem cells during development. Its expression has also been reported in different tissues under various pathological conditions. Specifically, nestin has been shown to be expressed in transformed cells of various human malignancies, and a correlation between its expression and the clinical course of some diseases has been proved. Furthermore, the coexpression of nestin with other stem cell markers was described as a CSC phenotype that was subsequently verified using tumorigenicity assays. The primary aim of this review is to summarize the recent findings regarding nestin expression in CSCs, its possible role in CSC phenotypes, particularly with respect to capacity for self-renewal, and its utility as a putative marker of CSCs.

HER2-signaling pathway, JNK and ERKs kinases, and cancer stem-like cells are targets of Bozepinib small compound

Identification of novel anticancer drugs presenting more than one molecular target and efficacy against cancer stem-like cells (CSCs) subpopulations represents a therapeutic need to combat the resistance and the high risk of relapse in patients. In the present work we show how Bozepinib [(RS)-2,6-dichloro-9-[1-(p-nitrobenzenesulfonyl)-1,2,3,5-tetrahydro-4,1-benzoxazepin-3-yl]-9H-purine], a small anti-tumor compound, demonstrated selectivity on cancer cells and showed an inhibitory effect over kinases involved in carcinogenesis, proliferation and angiogenesis. The cytotoxic effects of Bozepinib were observed in both breast and colon cancer cells expressing different receptor patterns. Bozepinib inhibited HER-2 signaling pathway and JNK and ERKs kinases. In addition, Bozepinib has an inhibitory effect on AKT and VEGF together with anti-angiogenic and anti-migratory activities. Moreover, the modulation of pathways involved in tumorigenesis by Bozepinib was also evident in microarrays analysis. Interestingly, Bozepinib inhibited both mamo- and colono-spheres formation and eliminated ALDH+ CSCs subpopulations at a low micromolar range similar to Salinomycin. Bozepinib induced the down-regulation of c-MYC, β-CATENIN and SOX2 proteins and the up-regulation of the GLI-3 hedgehog-signaling repressor. Finally, Bozepinib shows in vivo anti-tumor and anti-metastatic efficacy in xenotransplanted nude mice without presenting sub-acute toxicity. These findings support further studies on the therapeutic potential of Bozepinib in cancer patients.

CD133 and DNA-PK regulate MDR1 via the PI3K- or Akt-NF-κB pathway in multidrug-resistant glioblastoma cells in vitro

Chemotherapy is an adjuvant treatment for glioblastomas, however, chemotherapy remains palliative because of the development of multidrug resistance (MDR). Following prolonged chemotherapy, MDR protein 1 (MDR1) and CD133 increase in recurrent glioblastomas. CD133 positive (CD133+) glioma cancer stem-like cells (GCSCs) markedly promote drug resistance and exhibit increased DNA damage repair capability; thus they have a key role in determining tumor chemosensitivity. Although CD133, DNA-dependent protein kinase (DNA-PK), and MDR1 are elevated in CD133+ GCSCs, the relationship among these molecules has not been elucidated. In this study, MDR glioblastoma cell lines were created in response to prolonged doxorubicin chemotherapy. CD133, DNA-PK and MDR1 were markedly elevated in these cells. CD133 and DNA-PK may increase MDR1 via the phosphatidylinositol-3-kinase (PI3K)-Akt signal pathway. PI3K downstream targets Akt and nuclear factor (NF)-κB, which interacts with the MDR1 promoter, were also elevated in these cells. Downregulation of CD133 and DNA-PK by small interfering RNA, or inhibition of PI3K or Akt, decreased Akt, NF-κB and MDR1 expression. The results indicate that CD133 and DNA-PK regulate MDR1 through the PI3K- or Akt-NF-κB signal pathway. Consequently, a novel chemotherapeutic regimen targeting CD133 and DNA-PK in combination with traditional protocols may increase chemotherapeutic efficacy and improve prognosis for individuals who present with glioblastoma.

Evaluation of stem cell properties in human ovarian carcinoma cells using multi and single cell-based spheres assays

Years of research indicates that ovarian cancers harbor a heterogeneous mixture of cells including a subpopulation of so-called "cancer stem cells" (CSCs) responsible for tumor initiation, maintenance and relapse following conventional chemotherapies. Identification of ovarian CSCs is therefore an important goal. A commonly used method to assess CSC potential in vitro is the spheres assay in which cells are plated under non-adherent culture conditions in serum-free medium supplemented with growth factors and sphere formation is scored after a few days. Here, we review currently available protocols for human ovarian cancer spheres assays and perform a side-by-side analysis between commonly used multi cell-based assays and a more accurate system based on single cell plating. Our results indicate that both multi cell-based as well as single cell-based spheres assays can be used to investigate sphere formation in vitro. The more laborious and expensive single cell-based assays are more suitable for functional assessment of individual cells and lead to overall more accurate results while multi cell-based assays can be strongly influenced by the density of plated cells and require titration experiments upfront. Methylcellulose supplementation to multi cell-based assays can be effectively used to reduce mechanical artifacts.

Stealth lipid coated aquasomes bearing recombinant human interferon-α-2b offered prolonged release and enhanced cytotoxicity in ovarian cancer cells

PURPOSE

In present investigation, recombinant human interferon-α-2b (rhINF-α-2b) loaded aquasomes were prepared, optimized and overlaid with PEGylated phospholipid to offer prolong release and high therapeutic index against ovarian cancer, SKOV3 cells.

METHODS AND RESULTS

Central Composite Design (CCD) and Response Surface Methodology (RSM) were employed to calculate the optimized conditions, 1:3 core to coat ratio, sonication power of 12.5W and time of about 55min for preparation of aquasomes. Consequently, rhINF-α-2b-Py-5-P-Aq.somes exhibited higher protein loading capacity and retained structural conformations of rhINF-α-2b, as compared to rhINF-α-2b-Cellob-Aq.somes, rhINF-α-2b-Tre-Aq.somes and rhINF-α-2b-Core (CaHPO4). Further, optimized rhINF-α-2b-Py-5-P-Aq.somes was superimposed with phospholipid-PEG2000 to prolong the release pattern of rhINF-α-2b from aquasomes. The rhINF-α-2b-core (CaHPO4) released 97.3% of protein in 1h, while 95.3% of rhINF-α-2b was released by rhINF-α-2b-Tre-Aq.somes in 4h. Concurrently, rhINF-α-2b-Cellob-Aq.somes and rhINF-α-2b-Py-5-P-Aq.somes released 96.2% and 97.8% of rhINF-α-2b respectively in 6 and 8h. Ultimately, rhINF-α-2b-Py-5-P-Aq.somes-P-PEG2000 displayed evidence of its prolonged release pattern and released 98.1% of rhINF-α-2b in 336h. FT-IR and XRD substantiated the involvement of vigorous intermolecular hydrogen bonding and amorphous geometry in rhINF-α-2b-Py-5-P-Aq.somes. In last, rhINF-α-2b-Py-5-P-Aq.somes-P-PEG2000 exhibited the∼4.55, 1.92, 2.3, 2.8, and 3.84 fold reductions in IC50 as compared to free rhINF-α-2b, rhINF-α-2b-Py-5-P-Aq.somes, rhINF-α-2b-Cellob-Aq.somes, rhINF-α-2b-Tre-Aq.somes and rhINF-α-2b-Core (CaHPO4), respectively.

CONCLUSION

Therefore, rhINF-α-2b-Py-5-P-Aq.somes-P-PEG2000 warrant further in depth in vitro and in vivo antitumor study to scale up the technology for clinical intervention.

Stem cell characteristics of dormant cells and cisplatin‑induced effects on the stemness of epithelial ovarian cancer cells

Tumor dormancy is a common biological property of malignancies and a leading factor in treatment failure, metastasis and tumor recurrence. The present study generated mouse xenograft models by injection of PKH26‑labeled SKOV3 ovarian cancer cells, which were divided into two groups: The control group (SKOV3‑P tumors,) and the treatment group that generated resistant tumors following prolonged administration of cisplatin (SKOV3‑R tumors). Administration of cisplatin resulted in inhibition of the tumor growth and SKOV3‑R tumors coexisted with their host at a stable size. According to fluorochrome PKH26 retention, there were multiple cell clones (PKH26hi, PKH26low and PKH26neg cells) in the single cell line generated from xenograft tumors. PKH26hi subsets in SKOV3‑P and SKOV3‑R tumors were dormant cells, as the majority were arrested in G0/G1 phase and expressed high levels of the stem cell markers Oct‑4, Nestin, CD117 and CD44. PKH26hi subsets also demonstrated greater clonogenic capability in vitro and tumorigenicity in vivo, as compared with PKH26low and PKH26neg cells. Notably, chemotherapy was demonstrated to lead to the enrichment and enhanced stem‑like characteristics of dormant/slow‑cycling PKH26hi cells. The results of the present study have demonstrated for the first time, to the best of our knowledge, that dormant tumor cells exhibit stem‑like characteristics, and that cisplatin enhances these characteristics in epithelial ovarian cancer cells.

Contribution of TIP30 to chemoresistance in laryngeal carcinoma

Laryngeal squamous cell carcinoma (LSCC) is one of the most common carcinomas of the head and neck. Despite advances in diagnosis and treatment, the survival of patients with LSCC has not improved in the past two decades. TIP30, a newly identified tumour suppressor, appears to be involved in multiple processes during tumour development. Here, we investigated the involvement of TIP30 in chemoresistance of LSCC in vitro and in vivo. We showed that TIP30 expression decreased significantly in drug-selected cells (DSCs) of laryngeal carcinoma. Suppressing TIP30 enhanced resistance capability to multiple chemotherapy drugs, cell proliferation and self-renewal in Hep2 cells. Additionally, decreased self-renewal capacity and chemotherapeutic resistance were observed in DSCs overexpressing TIP30. Furthermore, TIP30 negatively regulated tumourigenesis and chemoresistance in LSCC cells subcutaneously transplanted into nude mice. Moreover, decreased TIP30 expression contributed to chemoresistance, self-renewal and proliferation of LSCC cells via nuclearlisation of β-catenin, a cell–cell adhesion and stem cell renewal regulator. Consistently, Kaplan–Meier and Cox proportional hazards regression modelling analyses showed that decreased TIP30 expression independently predicted poor survival in patients with LSCC. Taken together, our results reveal that TIP30 has a crucial role in chemoresistance of LSCC through the AKT/glycogen synthase kinase-3β/β-catenin signalling pathway and may be a promising candidate for improving LSCC chemotherapy.

The marine-derived fungal metabolite, terrein, inhibits cell proliferation and induces cell cycle arrest in human ovarian cancer cells

The difficulties faced in the effective treatment of ovarian cancer are multifactorial, but are mainly associated with relapse and drug resistance. Cancer stem-like cells have been reported to be an important contributor to these hindering factors. In this study, we aimed to investigate the anticancer activities of a bioactive fungal metabolite, namely terrein, against the human epithelial ovarian cancer cell line, SKOV3, primary human ovarian cancer cells and ovarian cancer stem-like cells. Terrein was separated and purified from the fermentation metabolites of the marine sponge-derived fungus, Aspergillus terreus strain PF26. Its anticancer activities against ovarian cancer cells were investigated by cell proliferation assay, cell migration assay, cell apoptosis and cell cycle assays. The ovarian cancer stem-like cells were enriched and cultured in a serum-free in vitro suspension system. Terrein inhibited the proliferation of the ovarian cancer cells by inducing G2/M phase cell cycle arrest. The underlying mechanisms involved the suppression of the expression of LIN28, an important marker gene of stemness in ovarian cancer stem cells. Of note, our study also demonstrated the ability of terrein to inhibit the proliferation of ovarian cancer stem-like cells, in which the expression of LIN28 was also downregulated. Our findings reveal that terrein (produced by fermention) may prove to be a promising drug candidate for the treatment of ovarian cancer by inhibiting the proliferation of cancer stem-like cells.

Enrichment for chemoresistant ovarian cancer stem cells from human cell lines

Cancer stem cells (CSCs) are defined as a subset of slow cycling and undifferentiated cells that divide asymmetrically to generate highly proliferative, invasive, and chemoresistant tumor cells. Therefore, CSCs are an attractive population of cells to target therapeutically. CSCs are predicted to contribute to a number of types of malignancies including those in the blood, brain, lung, gastrointestinal tract, prostate, and ovary. Isolating and enriching a tumor cell population for CSCs will enable researchers to study the properties, genetics, and therapeutic response of CSCs. We generated a protocol that reproducibly enriches for ovarian cancer CSCs from ovarian cancer cell lines (SKOV3 and OVCA429). Cell lines are treated with 20 µM cisplatin for 3 days. Surviving cells are isolated and cultured in a serum-free stem cell media containing cytokines and growth factors. We demonstrate an enrichment of these purified CSCs by analyzing the isolated cells for known stem cell markers Oct4, Nanog, and Prom1 (CD133) and cell surface expression of CD177 and CD133. The CSCs exhibit increased chemoresistance. This method for isolation of CSCs is a useful tool for studying the role of CSCs in chemoresistance and tumor relapse.

Sox2 gene amplification significantly impacts overall survival in serous epithelial ovarian cancer

Epithelial ovarian cancer (EOC) is the deadliest gynecologic cancer. Recently, the existence of ovarian cancer stem cells has been reported. Sox2, Nanog and Oct4 are key markers of "stemness". The objective of this study was to determine whether Sox2, Nanog, and Oct4 are associated with EOC and poor outcome. The expression of these markers was assessed by immunofluorescence staining and real-time RT-PCR in human EOC cell lines MDAH-2774 and SKOV-3, while the cancer genome atlas (TCGA) dataset was analyzed for associations with survival. Sox2, Nanog and Oct4 (POU5F1) were all detected by immunofluorescence staining and these results were confirmed by real-time RT-PCR. The TCGA dataset revealed a 26%, 9%, and 6% amplification of Sox2, Nanog and POU5F1, respectively. Additionally, K-M survival analyses showed a significant median overall survival difference (41 versus 48.3 months, P = .01) for Sox2 amplification, but not for Nanog (44.1 versus 36.2 months, P > .05) and POU5F1 (43.5 versus 45.0 months, P > .05). Our results suggest that Sox2 gene amplification significantly influences overall survival.

FOXO3a-mediated suppression of the self-renewal capacity of sphere-forming cells derived from the ovarian cancer SKOV3 cell line by 7-difluoromethoxyl-5,4'-di-n-octyl genistein

Carcinogenesis is predominantly dependent on the cancer stem cells (CSCs) residing or populating within the cancer. We previously demonstrated that the novel synthetic genistein analogue, 7-difluoromethoxyl-5,4'-di-n-octylgenistein (DFOG), induced apoptotic cell death of ovarian and gastric cancer cells. The present study demonstrated that sphere‑forming cells (SFCs) derived from the ovarian cancer cell-line SKOV3 possessed ovarian cancer stem-like cell (OCSLC) properties, including self-renewal and high tumorigenicity. DFOG may be effective in inhibiting the self‑renewal capacity of SFCs derived from the SKOV3 cell line. DFOG decreased the level of phosphorylated FOXO3a protein in SKOV3 cell‑derived SFCs. The inhibition of FOXO3a expression by siRNA significantly attenuated the ability of DFOG to inhibit the self-renewal capacity of SKOV3-derived SFCs. Our results suggested that DFOG has been demonstrated to significantly inhibit the self-renewal capacity of ovarian cancer stem cells (OCSCs) through a mechanism partly dependent on the activation of FOXO3a.