Stem cells and cancer: two faces of eve

The connection between the Th17 cell related cytokines and cancer stem cells in cancer: Novel therapeutic targets

Cancer Stem Cells (CSCs) are the subpopulation of cells present in the different types of cancers with capabilities of self-renewal, differentiation, and tumorigenicity when transplanted into an animal host. The research work on the CSC has been providing a promising approach for the improvement of cancer therapies in the future. The CSCs have a close connection with the cytokines related with the T helper 17 (Th17) cell and other factors present in the tumor microenvironment, and these play a pivotal role in tumor progression and metastasis. The properties of CSCs are well defined in various type of tumor which is mainly developed by chemically and spontaneously in murine cancer model but in human defined primarily on acute myeloid leukemia, glioma, and breast cancer. The role of Th1, Th2, Natural Killer cells are well described in the cancer biology, but the Th17 cells are the subset which is recently exploited, and lots of research are going on. In this Review, we summarize current findings of the characteristics and functions of the Th17 cell and its signature cytokines in different cancers and their interconnections with cancer stem cells and with their markers. We have also discussed the functional properties of CSCs and how the CSCs markers can be distinguished from normal stem cells markers. We have also talked about the strategies that are efficiently targeting of CSCs and Th17 cells in different cancers.

Cellular and molecular biology of cancer stem cells in melanoma: Possible therapeutic implications

Malignant melanoma is a tumor characterized by a very high level of heterogeneity, responsible for its malignant behavior and ability to escape from standard therapies. In this review we highlight the molecular and biological features of the subpopulation of cancer stem cells (CSCs), well known to be characterized by self-renewal properties, deeply involved in triggering the processes of tumor generation, metastasis, progression and drug resistance. From the molecular point of view, melanoma CSCs are identified and characterized by the expression of stemness markers, such as surface markers, ATP-binding cassette (ABC) transporters, embryonic stem cells and intracellular markers. These cells are endowed with different functional features. In particular, they play pivotal roles in the processes of tumor dissemination, epithelial-to-mesenchymal transition (EMT) and angiogenesis, mediated by specific intracellular signaling pathways; moreover, they are characterized by a unique metabolic reprogramming. As reported for other types of tumors, the CSCs subpopulation in melanoma is also characterized by a low immunogenic profile as well as by the ability to escape the immune system, through the expression of a negative modulation of T cell functions and the secretion of immunosuppressive factors. These biological features allow melanoma CSCs to escape standard treatments, thus being deeply involved in tumor relapse. Targeting the CSCs subpopulation is now considered an attractive treatment strategy; in particular, combination treatments, based on both CSCs-targeting and standard drugs, will likely increase the therapeutic options for melanoma patients. The characterization of CSCs in liquid biopsies from single patients will pave the way towards precision medicine.

DREF Genetically Counteracts Mi-2 and Caf1 to Regulate Adult Stem Cell Maintenance

Active adult stem cells maintain a bipotential state with progeny able to either self-renew or initiate differentiation depending on extrinsic signals from the surrounding microenvironment. However, the intrinsic gene regulatory networks and chromatin states that allow adult stem cells to make these cell fate choices are not entirely understood. Here we show that the transcription factor DNA Replication-related Element Factor (DREF) regulates adult stem cell maintenance in the Drosophila male germline. A temperature-sensitive allele of DREF described in this study genetically separated a role for DREF in germline stem cell self-renewal from the general roles of DREF in cell proliferation. The DREF temperature-sensitive allele caused defects in germline stem cell self-renewal but allowed viability and division of germline stem cells as well as cell viability, growth and division of somatic cyst stem cells in the testes and cells in the Drosophila eye. Germline stem cells mutant for the temperature sensitive DREF allele exhibited lower activation of a TGF-beta reporter, and their progeny turned on expression of the differentiation factor Bam prematurely. Results of genetic interaction analyses revealed that Mi-2 and Caf1/p55, components of the Nucleosome Remodeling and Deacetylase (NuRD) complex, genetically antagonize the role of DREF in germline stem cell maintenance. Taken together, these data suggest that DREF contributes to intrinsic components of the germline stem cell regulatory network that maintains competence to self-renew.

Many adult tissues are maintained throughout life by the dual ability of adult stem cells to produce progeny that either self-renew or differentiate to replace specialized cells lost to turnover or damage. Although signals from the surrounding microenvironment have been shown to regulate the choice between self-renewal and onset of differentiation, the intrinsic gene regulatory programs that set up and maintain this bipotential state are not well understood. In this report we describe antagonistic components of an intrinsic stem cell program important for maintaining the balance between self-renewal and differentiation in Drosophila male germline adult stem cell lineage. We identified a temperature-sensitive mutant in the transcription factor DNA Replication-related Element Factor (DREF) gene that disrupts the ability of germline stem cells to self-renew, but not stem cell viability, ability to divide or differentiate under the same conditions. DREF mutant germline stem cells showed defects in the TGF-beta signaling pathway, a pathway that is critical for maintaining the stem cell population. Genetic interaction analyses revealed that Mi-2 and Caf1/p55, components of the Nucleosome Remodeling and Deacetylase complex genetically antagonize the role of DREF in germline stem cell maintenance. We propose that DREF contributes to a transcriptional environment necessary for maintaining a bi-potential stem cell state able to properly respond to extrinsic niche signals.

Blastemal NCAM+ALDH1+ Wilms' tumor cancer stem cells correlate with disease progression and poor clinical outcome: A pilot study

BACKGROUND

Cancer Stem Cells (CSCs) have been suggested as the culprit responsible for tumor resistance to treatment and disease recurrence. Wilms' tumor (WT) is a paradigm for studying the relation between development and tumorigenesis, showing three main histological elements: undifferentiated blastema, epithelia and stroma, mimicking human kidney development. NCAM + ALDH1+ cells were previously found to contain the cancer stem like-cell population in WT. Thus far, the correlation between histologic characterization of this cell population, clinicopathologic parameters and prognostic outcome has yet been investigated in WT.

PROCEDURES

Paraffin-imbedded primary WT specimens from twenty-four patients were immunostained for NCAM and ALDH1. Positivity and histologic compartment localization were determined by two independent observers, blinded to the clinical outcome. Clinicopathologic parameters and prognostic outcomes were determined based on the patients' medical records. The association of NCAM and ALDH1 co-localization with clinicopathologic characteristics was analyzed byχ²-test. Survival analysis was carried out by the log-rank test using Kaplan-Meier method.

RESULTS

Blastemal co-localization of NCAM and ALDH1 was observed in 33% of WTs. Metastases, ICE chemotherapy protocol, blastemal predominance following preoperative chemotherapy, recurrence and patient demise were found to significantly correlate with blastemal NCAM + ALDH1+ cell staining (p < 0.05). A significant inverse correlation between blastemal double positive cells, disease-free survival and overall survival was also observed.

CONCLUSIONS

WT blastemal NCAM + ALDH1+ CSCs significantly correlate with adverse clinicopathologic parameters and poorer prognosis. These results underscore the role of CSCs in disease progression. Additionally, this pilot study supports the addition of these markers for risk stratification of WTs.

Head and neck cancer management and cancer stem cells implication

Head and neck squamous cell carcinomas (HNSCCs) arise in the mucosal linings of the upper aerodigestive tract and are heterogeneous in nature. Risk factors for HNSCCs are smoking, excessive alcohol consumption, and the human papilloma virus. Conventional treatments are surgery, radiotherapy, chemotherapy, or a combined modality; however, no international standard mode of therapy exists. In contrast to the conventional model of clonal evolution in tumor development, there is a newly proposed theory based on the activity of cancer stem cells (CSCs) as the model for carcinogenesis. This “CSC hypothesis” may explain the high mortality rate, low response to treatments, and tendency to develop multiple tumors for HNSCC patients. We review current knowledge on HNSCC etiology and treatment, with a focus on CSCs, including their origins, identifications, and effects on therapeutic options.

A phase 1b dose escalation study of ipafricept (OMP54F28) in combination with paclitaxel and carboplatin in patients with recurrent platinum-sensitive ovarian cancer

OBJECTIVES

The WNT pathway is an important oncologic driver of epithelial ovarian cancer (EOC). The first-in-class recombinant fusion protein ipafricept (IPA) blocks Wnt signaling through binding of Wnt ligands. This phase Ib trial was designed to determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RPh2) for IPA in combination with taxane and platinum therapy (C/P).

METHODS

Dose escalation started with a standard 3 + 3 design for IPA/C/P with q3w intravenous IPA on Day 1, in cycles 1 to 6 with C (AUC = 5 mg/ml·min) and P (175 mg/m²). For enhanced bone safety the trial was revised to 6-patient cohorts with a q3w regimen of IPA on Day 1 and C/P on Day 3 (IPA → C/P).

RESULTS

37 patients have been treated; 30 of whom were treated following protocol revision to q3w IPA(D1) → C/P(D3) (2 & 4 mg/kg). IPA-related TEAEs that occurred in ≥15% included: fatigue (40%); nausea (35%); diarrhea and decreased appetite (22%) each; dysgeusia (19%); and vomiting (16.2%). 22% reported ≥1 IPA related TEAE Grade ≥3 the most common of which was neutropenia at 16%. There were no DLTs; the MTD was not reached. The maximum administered dose based on bone safety was 6 mg/kg. The overall response rate (ORR) was 75.7%. Median PFS was 10.3 months (95% CI 8.5-14.2) and OS 33 months (95% CI 23.4-NR).

CONCLUSIONS

IPA is well tolerated in combination with sequential C/P. ORR, PFS and OS are comparable to historical data but bone toxicity at efficacy doses of this particular Wnt inhibitor limit further development in EOC.

ALDH1 expression correlates with an epithelial-like phenotype and favorable prognosis in lung adenocarcinoma: a study based on immunohistochemistry and mRNA expression data

PURPOSE

Cancer stem cells (CSC) and epithelial-mesenchymal transition (EMT) pathways are crucial for cancer progression. However, synergistic interactions between CSC and EMT are not clear in non-small cell lung cancer (NSCLC). The objective of this study was to investigate CSC markers such as CD44, NANOG, and ALDH1 expression and its correlation with EMT markers in NSCLC patients. Its association with survival was also determined.

METHODS

CD44, NANOG, and ALDH1 protein expression was evaluated in 267 resected NSCLC and its correlation with e-cadherin, β-catenin, p120 catenin, vimentin, SNAIL, and TWIST expressions was determined based on immunohistochemical and mRNA expression data from The Cancer Genome Atlas (TCGA) database. Survival analyses also were performed based on immunohistochemistry and mRNA expression data from Gene Expression Omnibus dataset.

RESULTS

ALDH1 expression in lung adenocarcinoma was positively correlated with the epithelial-like phenotype, low vimentin and low TWIST in immunohistochemical and mRNA expression data. NANOG and ALDH1 expressions measured by immunohistochemical and mRNA expression profiling data of adenocarcinomas were associated with a favorable prognosis. ALDH1 was an independent favorable prognostic marker for overall survival or recurrence-free survival in adenocarcinoma (P = 0.026 and P = 0.033, respectively). The epithelial-like phenotype expressing P120-catenin and beta-catenin was associated with a favorable prognosis; however, the TWIST-expressing mesenchymal-like phenotype was correlated with an unfavorable prognosis.

CONCLUSIONS

NANOG and ALDH1 protein or mRNA expression showed improved prognosis in adenocarcinoma alone. ALDH1 expression correlated with an epithelial-like phenotype.

Calcium channels and cancer stem cells

Cancer stem cells (CSC's) have emerged as a key area of investigation due to associations with cancer development and treatment resistance, related to their ability to remain quiescent, self-renew and terminally differentiate. Targeting CSC's in addition to the tumour bulk could ensure complete removal of the cancer, lessening the risk of relapse and improving patient survival. Understanding the mechanisms supporting the functions of CSC's is essential to highlight targets for the development of therapeutic strategies. Changes in intracellular calcium through calcium channel activity is fundamental for integral cellular processes such as proliferation, migration, differentiation and survival in a range of cell types, under both normal and pathological conditions. Here in we highlight how calcium channels represent a key mechanism involved in CSC function. It is clear that expression and or function of a number of channels involved in calcium entry and intracellular store release are altered in CSC's. Correlating with aberrant proliferation, self-renewal and differentiation, which in turn promoted cancer progression and treatment resistance. Research outlined has demonstrated that targeting altered calcium channels in CSC populations can reduce their stem properties and induce terminal differentiation, sensitising them to existing cancer treatments. Overall this highlights calcium channels as emerging novel targets for CSC therapies.

Non-coding RNAs as potential therapeutic targets in breast cancer

Paradigm shifting studies especially involving non-coding RNAs (ncRNAs) during last few decades have significantly changed the scientific perspectives regarding the complexity of cellular signalling pathways. Several studies have shown that the non-coding RNAs, initially ignored as transcriptional noise or products of erroneous transcription; actually regulate plethora of biological phenomena ranging from developmental processes to various diseases including cancer. Current strategies that are employed for the management of various cancers including that of breast fall short when their undesired side effects like Cancer Stem Cells (CSC) enrichment, low recurrence-free survival and development of drug resistance are taken into consideration. This review aims at exploring the potential role of ncRNAs as therapeutics in breast cancer, by providing a comprehensive understanding of their mechanism of action and function and their crucial contribution in regulating various aspects of breast cancer progression such as cell proliferation, angiogenesis, EMT, CSCs, drug resistance and metastasis. In addition, we also provide information about various strategies that can be employed or are under development to explore them as potential moieties that may be used for therapeutic intervention in breast cancer.

Co-expression of CD44/MyD88 is a poor prognostic factor in advanced epithelial ovarian cancer

Background

Cluster of differentiation 44 (CD44)/myeloid differentiation factor 88 (MyD88) is the molecular characterization of EOC stem cells. An important characteristic of CD44+/MyD88+ epithelial ovarian cancer (EOC) cells, which differentiate them from the CD44-/MyD88- EOC cells, is the presence of a functional TLR4-MyD88-NFkB pathway. The aim of our study is to investigate the clinical significance of CD44/MyD88 co-expression in EOC.

Methods

A total of 138 specimens of ovarian tissues was detected CD44 and MyD88 expression by immunocytochemistry, including EOC (N=108), borderline tumors (N=10), benign cysts (N=10) and normal ovarian tissue (N=10). The association of CD44/MyD88 co-expression with clinicopathological factors and outcomes was analyzed.

Results

The expression of CD44 was showed distinct difference in EOC (53 of 108, 49.1%), in borderline tumors (3 of 10, 30.0%), in benign cysts (2 of 10, 20.0%) and normal ovarian (2 of 10, 20.0%). A total of 41 (38.0%) cancers showed a combined expression of CD44/MyD88. The expression of CD44 and MyD88 had definitely correlativity (r=0.21, P=0.026). CD44/MyD88 co-expression was associated with tumor progression, metastasis, and recurrence in advanced EOC, and an independent prognostic factor for disease-free survival and overall survival.

Conclusions

CD44/MyD88 co-expression has been shown to contribute to EOC progression and outcome directly and has a promising as a therapeutic target in EOC.

Nanomedicine-based formulations containing ω-3 polyunsaturated fatty acids: potential application in cardiovascular and neoplastic diseases

Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) are dietary factors involved in the prevention of cardiovascular, inflammatory, and neoplastic diseases. A multidisciplinary approach – based on recent findings in nutritional science, lipid biochemistry, biotechnology, and biology of inflammation and cancer – has been recently employed to develop ω-3 PUFA-containing nanoformulations with an aim to protect these fatty acids from degradation, increase their bioavailability and delivery to target tissues, and, thus, enhance their bioactivity. In some cases, these nanoformulations were designed to administer ω-3 PUFAs in combination with other nutraceuticals or conventional/innovative drugs. The aim of this strategy was to increase the activities of the compounds contained in the nanoformulation and to reduce the adverse effects often induced by drugs. We herein analyze the results of papers evaluating the potential use of ω-3 PUFA-containing nanomaterials in fighting cardiovascular diseases and cancer. Future directions in this field of research are also provided.

Low CD8⁺ T Cell Infiltration and High PD-L1 Expression Are Associated with Level of CD44⁺/CD133⁺ Cancer Stem Cells and Predict an Unfavorable Prognosis in Pancreatic Cancer

Cancer immunotherapy targeting immune checkpoints has exhibited promising clinical outcomes in many cancers, but it offers only limited benefits for pancreatic cancer (PC). Cancer stem cells (CSCs), a minor subpopulation of cancer cells, play important roles in tumor initiation, progression, and drug resistance. Accumulating evidence suggests that CSCs employ immunosuppressive effects to evade immune system recognition. However, the clinical implications of the associations among CD8⁺ T cells infiltration, programmed death receptor ligand-1 (PD-L1) expression, and CSCs existence are poorly understood in PC. Immunostaining and quantitative analysis were performed to assess CD8⁺ T cells infiltration, PD-L1 expression, and their relationship with CD44⁺/CD133⁺ CSCs and disease progression in PC. CD8⁺ T cells infiltration was associated with better survival while PD-L1 expression was correlated with PC recurrence. Both the low CD8⁺ T cells infiltration/high PD-L1 expression group and the high CD8⁺ T cells infiltration/high PD-L1 expression group show high levels of CD44⁺/CD133⁺ CSCs, but patients with low CD8⁺ T cells infiltration/high PD-L1 expression had worse survival and higher recurrence risk than those with high CD8⁺ T cells infiltration/high PD-L1 expression. Moreover, high infiltration of CD8⁺ T cells could reduce unfavorable prognostic effect of high co-expression of PD-L1 and CD44/CD133. Our study highlights an interaction among CD8⁺ T cells infiltration, PD-L1 expression, and CD44⁺/CD133⁺ CSCs existence, which contributes to PC progression and immune evasion.

The Role of SVZ Stem Cells in Glioblastoma

As most common primary brain cancer, glioblastoma is also the most aggressive and malignant form of cancer in the adult central nervous system. Glioblastomas are genetic and transcriptional heterogeneous tumors, which in spite of intensive research are poorly understood. Over the years conventional therapies failed to affect a cure, resulting in low survival rates of affected patients. To improve the clinical outcome, an important approach is to identify the cells of origin. One potential source for these are neural stem cells (NSCs) located in the subventricular zone, which is one of two niches in the adult nervous system where NSCs with the capacity of self-renewal and proliferation reside. These cells normally give rise to neuronal as well as glial progenitor cells. This review summarizes current findings about links between NSCs and cancer stem cells in glioblastoma and discusses current therapeutic approaches, which arise as a result of identifying the cell of origin in glioblastoma.

Palmitate acid promotes gastric cancer metastasis via FABP5/SP1/UCA1 pathway

Background

Gastric cancer (GC) has a clear predilection for metastasis toward omentum which is primarily composed of adipose tissue, combine with our previous research that long non-coding RNA Urothelial cancer associated 1 (UCA1) could promote the peritoneal metastasis of GC, we put forward the hypothesis that fatty acids (FAs) might contribute to these phenomena and a connection between FAs and UCA1 might exist.

Methods

TCGA database was applied to investigate the expression levels of UCA1 in GC tissues and normal gastric tissues and its correlation with GC patients’ survival. Transfection of siRNA was utilized to knockdown cellular levels of FA-binding protein 5 (FABP5), SP1, UCA1. Migration assay and invasion assay were performed to assess the biological effects of palmitate acid (PA), FABP5, SP1 and UCA1 on GC metastasis. The underlying mechanism was investigated via western blot, immunofluorescence (IF), semi-quantitative RT-PCR (sqRT-PCR) and quantitative RT-PCR (qRT-PCR) analysis.

Results

Here we demonstrated that PA could promote the nuclear transport of FABP5, which then increased the nuclear protein levels of SP1. Consequently, GC cellular expression levels of UCA1 were increased which promoted the metastatic properties of GC. Besides, the cellular levels of UCA1 in GC tumor tissues were significantly higher than that in normal tissues. Its levels in GC tumor tissues also negatively correlated with the prognosis of GC patients using TCGA database.

Conclusions

Our research revealed the potential tumor-promoting effect of FA transport protein FABP5. We also established a connection between non-coding RNA and FA metabolism, treatment targeted either to patients’ diets or FABP5 might improve the prognosis of GC patients.

Conditioned media derived from mesenchymal stem cell cultures: The next generation for regenerative medicine

Recent studies suggest that the main driving force behind the therapeutic activity observed in mesenchymal stem cells (MSCs) are the paracrine factors secreted by these cells. These biomolecules also trigger antiapoptotic events to prevent further degeneration of the diseased organ through paracrine signalling mechanisms. In comparison with the normal physiological conditions, an increased paracrine gradient is observed within the peripheral system of diseased organs that enhances the migration of tissue-specific MSCs towards the site of infection or injury to promote healing. Thus, upon administration of conditioned media derived from mesenchymal stem cell cultures (MSC-CM) could contribute in maintaining the increased paracrine factor gradient between the diseased organ and the stem cell niche in order to speed up the process of recovery. Based on the principle of the paracrine signalling mechanism, MSC-CM, also referred as the secretome of the MSCs, is a rich source of the paracrine factors and are being studied extensively for a wide range of regenerative therapies such as myocardial infarction, stroke, bone regeneration, hair growth, and wound healing. This article highlights the current technological applications and advances of MSC-CM with the aim to appraise its future potential as a regenerative therapeutic agent.

Suppression of miR-21-3p enhances TRAIL-mediated apoptosis in liver cancer stem cells by suppressing the PI3K/Akt/Bad cascade via regulating PTEN

Background

TNF-related apoptosis-inducing ligand (TRAIL) functions as a selective apoptosis-inducing ligand in cancer cells with normal cells remaining unaffected; however, resistance limits its anticancer properties. Cancer stem cells (CSCs) are involved in the treatment of resistant cancer cases including liver cancer (LC). The aim of this study was to look into the approaches for increasing the sensitivity of liver cancer stem cells (LCSCs) toward TRAIL.

Methodology

PLC, HepG2 and Huh7 LC cell lines were used in this study. Quantitative reverse transcription PCR (qRT-PCR) analysis was done for evaluating the expression of miR-21-3b. Fluorescent-activated cell-sorting equipment was used for separation and identification of LCSCs and non-LCSCs. The cells were transfected with RNA along with miR-21-3p mimics, anti- miR-21-3p, miR-NC and the phosphatase and tensin homologue (PTEN) siRNA. MTT assay for cell viability, Luciferase assay for luciferase activity, Western blots for the expression of proteins and flow cytometry for the measurement of ROS and apoptosis, respectively, were carried out. Tumor xenografts nude mice were used for tumor growth in vivo.

Results

We found that miR-21-3p was overexpressed in LCSCs compared to non-LCSCs and that the suppression of miR-21-3p along with anti-miR-21-3p enhanced the sensitivity of LCSCs to TRAIL-mediated apoptosis. We further found that miR-21-3p regulated the expression of PTEN in Huh7-LCSCs directly and that the suppression of miR-21-3p enhanced the levels of PTEN. The study confirmed that inhibition of the PI3K/Akt/Bad signaling pathway was involved in enhancing TRAIL-mediated apoptosis of LC cells.

Conclusion

The study suggested that overexpression of miR-21-3p suppresses the sensitivity to TRAIL in LCSCs. This study concludes that the suppression of miR-21-3p is a potential approach for enhancing the sensitivity of LC cells toward TRAIL by PI3K/Akt/Bad cascade via the miR-21-3p/PTEN axis.

Immunohistochemical Analysis of Cancer Stem Cell Marker Expression in Papillary Thyroid Cancer

Cancer stem cell (CSC) markers have prognostic significance in various cancers, but their clinical significance in papillary thyroid carcinoma (PTC) has not been demonstrated. In this study, CSC markers expressed in PTC and their relationships with prognosis were evaluated. We constructed tissue microarrays for 386 PTC cases, divided it into 42 low risk cases and 344 intermediate risk cases according to the American Thyroid Association 2009 Risk Stratification System. Immunohistochemical staining of CSC markers (CD15, CD24, CD44, CD166, and ALDH1A1) was performed, and the proportion of stained cells and immunostaining intensity were evaluated to determine positive marker expression. The relationships between CSC marker expression and other clinicopathological parameters or survival were analyzed. CD15 expression was higher in PTC with intermediate risk than in PTC with low risk (29.4 vs. 11.9%, p = 0.017). According to a multivariate analysis, CD15, CD44, CD166, and ALDH1A1 positivity were independently associated with a shorter progression-free survival (PFS) (odds ratio [OR]: 1.929, 2.960, 7.485, and 3.736; p = 0.016, p = 0.026, p < 0.001, and p = 0.006, respectively). Higher N and cancer stage were the only other clinical factors associated with a shorter PFS (OR: 2.953 and 1.898, p = 0.011 and p = 0.034). Overexpression of CSC markers in PTC was associated with shorter PFS during follow-up. Immunohistochemical staining of CSC markers may provide useful information for predicting patient outcomes.

Loss of heparan sulfate in the niche leads to tumor-like germ cell growth in the Drosophila testis

The stem cell niche normally prevents aberrant stem cell behaviors that lead to cancer formation. Recent studies suggest that some cancers are derived from endogenous populations of adult stem cells that have somehow escaped from normal control by the niche. However, the molecular mechanisms by which the niche retains stem cells locally and tightly controls their divisions are poorly understood. Here, we demonstrate that the presence of heparan sulfate (HS), a class glygosaminoglycan chains, in the Drosophila germline stem cell niche prevents tumor formation in the testis. Loss of HS in the niche, called the hub, led to gross changes in the morphology of testes as well as the formation of both somatic and germline tumors. This loss of hub HS resulted in ectopic signaling events in the Jak/Stat pathway outside the niche. This ectopic Jak/Stat signaling disrupted normal somatic cell differentiation, leading to the formation of tumors. Our finding indicates a novel non-autonomous role for niche HS in ensuring the integrity of the niche and preventing tumor formation.

BORIS: a key regulator of cancer stemness

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

Protecting and Diversifying the Germline

Gametogenesis represents the most dramatic cellular differentiation pathways in both female and male flies. At the genome level, meiosis ensures that diploid germ cells become haploid gametes. At the epigenome level, extensive changes are required to turn on and shut off gene expression in a precise spatiotemporally controlled manner. Research applying conventional molecular genetics and cell biology, in combination with rapidly advancing genomic tools have helped us to investigate (1) how germ cells maintain lineage specificity throughout their adult reproductive lifetime; (2) what molecular mechanisms ensure proper oogenesis and spermatogenesis, as well as protect genome integrity of the germline; (3) how signaling pathways contribute to germline-soma communication; and (4) if such communication is important. In this chapter, we highlight recent discoveries that have improved our understanding of these questions. On the other hand, restarting a new life cycle upon fertilization is a unique challenge faced by gametes, raising questions that involve intergenerational and transgenerational epigenetic inheritance. Therefore, we also discuss new developments that link changes during gametogenesis to early embryonic development-a rapidly growing field that promises to bring more understanding to some fundamental questions regarding metazoan development.

A first-in-human phase 1a study of the bispecific anti-DLL4/anti-VEGF antibody navicixizumab (OMP-305B83) in patients with previously treated solid tumors

Purpose Navicixizumab (OMP-305B83) is a bispecific antibody that inhibits delta-like ligand 4 and vascular endothelial growth factor. This Phase 1a trial assessed escalating doses of navicixizumab in refractory solid tumors patients. Design A 3 + 3 dose escalation design was used followed by the treatment of additional patients in an expansion cohort. Study objectives were determination of the maximum tolerated dose, safety, pharmacokinetics, pharmacodynamics, immunogenicity and efficacy. Results Sixty-six patients were treated once every 3 weeks in 8 dose-escalation cohorts (0.5, 1, 2.5, 3.5, 5, 7.5, 10, and 12.5 mg/kg) and an expansion cohort (7.5 mg/kg). The median age was 60 years and 68% of the patients were female. The most commonly enrolled tumor types were ovarian (12), colorectal (11) and breast, pancreatic, uterine and endometrial (4 each) cancers. As only 1 dose limiting toxicity occurred, the maximum tolerated dose was not reached, but 7.5 mg/kg was chosen as the dose for the expansion cohort. The treatment related adverse events (≥15% of patients) were hypertension (57.6%), headache (28.8%), fatigue (25.8%), and pulmonary hypertension (18.2%). Pulmonary hypertension was mostly asymptomatic at doses ≤5 mg/kg (6 Gr1, 1 Gr2), but was more severe at higher doses (4 Gr2, 1 Gr3). Navicixizumab's half-life was 11.4 days and there was a moderate (29%) incidence of anti-drug antibody formation. Four patients (3 ovarian cancer, 1 uterine carcinosarcoma) had a partial response and 17 patients had stable disease. Nineteen patients had a reduction in the size of their target lesions including 7/11 patients with ovarian cancer. Four patients remained on study for >300 days and 2 of these patients were on study for >500 days. Conclusions Navicixizumab can be safely administered with manageable toxicities and these data showed preliminary signs of antitumor activity in multiple tumor types, but was most promising in ovarian cancer. As a result these data justify its continued development in combination Phase 1b clinical trials.

Identification, Histological Characterization, and Dissection of Mouse Prostate Lobes for In Vitro 3D Spheroid Culture Models

Genetically engineered mouse models (GEMMs) serve as effective pre-clinical models for investigating most types of human cancers, including prostate cancer (PCa). Understanding the anatomy and histology of the mouse prostate is important for the efficient use and proper characterization of such animal models. The mouse prostate has four distinct pairs of lobes, each with their own characteristics. This article demonstrates the proper method of dissection and identification of mouse prostate lobes for disease analysis. Post-dissection, the prostate cells can be further cultured in vitro for mechanistic understanding. Since mouse prostate primary cells tend to lose their normal characteristics when cultured in vitro, we outline here a method for isolating the cells and growing them as 3D spheroid cultures, which is effective for preserving the physiological characteristics of the cells. These 3D cultures can be used for analyzing cell morphology and behavior in near-physiological conditions, investigating altered levels and localizations of key proteins and pathways involved in the development and progression of a disease, and looking at responses to drug treatments.

The emerging role of lncRNAs in the regulation of cancer stem cells

BACKGROUND

Tumors contain a functional subpopulation of cells that exhibit stem cell properties. These cells, named cancer stem cells (CSCs), play significant roles in the initiation and progression of cancer. Long non-coding RNAs (lncRNAs) can act at the transcriptional, posttranscriptional and translational level. As such, they may be involved in various biological processes such as DNA damage repair, inflammation, metabolism, cell survival, cell signaling, cell growth and differentiation. Accumulating evidence indicates that lncRNAs are key regulators of the CSC subpopulation, thereby contributing to cancer progression. The aim of this review is to overview current knowledge about the functional role and the mechanisms of action of lncRNAs in the initiation, maintenance and regulation of CSCs derived from different neoplasms. These lncRNAs include CTCF7, ROR, DILC, HOTAIR, H19, HOTTIP, ATB, HIF2PUT, SOX2OT, MALAT-1, CUDR, Lnc34a, Linc00617, DYNC2H1-4, PVT1, SOX4 and ARSR Uc.283-plus. Furthermore, we will illustrate how lncRNAs may regulate asymmetric CSC division and contribute to self-renewal, drug resistance and EMT, thus affecting the metastasis and recurrence of different cancers. In addition, we will highlight the implications of targeting lncRNAs to improve the efficacy of conventional drug therapies and to hamper CSC survival and proliferation.

CONCLUSIONS

lncRNAs are valuable tools in the search for new targets to selectively eliminate CSCs and improve clinical outcomes. LncRNAs may serve as excellent therapeutic targets because they are stable, easily detectable and expressed in tissue-specific contexts.

Evaluation of cancer stemness in breast cancer and glioblastoma spheroids in vitro

In this study, the effect of spheroid formation, as a model of three-dimensional (3D) culture systems, on the cancer stemness of human breast cancer (MCF-7) and human glioma (U87-MG) cell lines was analyzed. We compared the expression of pluripotency genes, the presence of various cancer stem cell populations, migration and proliferation capacities of cells cultured as monolayers or spheroids. MCF-7 cells formed uniform spheroids in vitro, upregulated the expression of stem cell markers both at gene and protein levels and increased their migration capacities when cultured in 3D systems. When a CSC targeting metabolic drug, metformin was used, multiple drug resistance genes (ABC transporters) were downregulated and the anti-cancer activity of 5-fluorouracil was enhanced. In summary, this study proved that the use of 3D culture systems such as spheroids can be used in CSC-related research. Therefore, studies involving 3D culture systems will help scientists to discover new CSC markers, show more realistic drug responses, and better evaluate tumor proliferation and morphology changes.

Tracing the path of cancer initiation: the AA protein-based model for cancer genesis

Background

Cancer is a defiant disease which cure is still far from being attained besides the colossal efforts and financial means deployed towards that end. The continuing setbacks encountered with today’s arsenal of anti-cancer drugs and cancer therapy modalities; show the need for a radical approach in order to get to the root of the problem. And getting to the root of cancer initiation and development leads us to challenge the present dogmas surrounding the pathogenesis of this disease.

Results

This comprehensive analysis brings to light the following points: (i) Cancer with its plethora of genetic and cellular symptoms could originate from one major event switching a cell from normalcy-to-malignancy; (ii) The switching event is postulated to involve a pathological breakup of a non-mutated protein, called here AA protein, resulting in the acquisition of new cellular functions present only in cancer cells; (iii) Following this event, DNA mutations begin to accumulate as secondary events to ensure perpetuity of cancer. Supporting arguments for this protein-based model come mainly from these observations: (i) The AA protein-based model reconciles together the clonal-and-stem cell theories into one inclusive model; (ii) The breakup of a normal protein could be behind the cancer-linked inflammation symptom; (iii) Cancer hallmarks are but adaptive traits, earned as a result of the switch from normalcy-to-malignancy.

Conclusions

Adaptation of cancer cells to their microenvironment and to different anti-cancer drugs is deemed here as the ultimate cancer hallmark, that needs to be understood and controlled. This adaptive power of cancer cells parallels that of bacteria also known with their resistance to a large range of substances in nature and in the laboratory. Consequently, cancer development could be viewed as a backward walk on the line of Evolution. Finally this unprecedented analysis demystifies cancer and puts the finger on the core problem of malignancy while offering ideas for its control with the ultimate goal of leading to its cure.

Cytokine Induced Killer cells are effective against sarcoma cancer stem cells spared by chemotherapy and target therapy

Metastatic bone and soft tissue sarcomas often relapse after chemotherapy (CHT) and molecular targeted therapy (mTT), maintaining a severe prognosis. A subset of sarcoma cancer stem cells (sCSC) is hypothesized to resist conventional drugs and sustain disease relapses. We investigated the immunotherapy activity of cytokine induced killer cells (CIK) against autologous sCSC that survived CHT and mTT. The experimental platform included two aggressive bone and soft tissue sarcoma models: osteosarcoma (OS) and undifferentiated-pleomorphic sarcoma (UPS).

To visualize putative sCSC we engineered patient-derived sarcoma cultures (2 OS and 3 UPS) with a lentiviral sCSC-detector wherein the promoter of stem-gene Oct4 controls the expression of eGFP.

We visualized a fraction of sCSC (mean 24.2 ± 5.2%) and confirmed their tumorigenicity in vivo. sCSC resulted relatively resistant to both CHT and mTT in vitro. Therapeutic doses of doxorubicin significantly enriched viable eGFP⁺sCSC in both OS (2.6 fold, n = 16) and UPS (2.3 fold, n = 29) compared to untreated controls. Treatment with sorafenib (for OS) and pazopanib (for UPS) also determined enrichment (1.3 fold) of viable eGFP⁺sCSC, even if less intense than what observed after CHT.

Sarcoma cells surviving CHT and mTT were efficiently killed in vitro by autologous CIK even at minimal effector/target ratios (40:1 = 82%, 1:4 = 29%, n = 13). CIK immunotherapy did not spare sCSC that were killed as efficiently as whole sarcoma cell population. The relative chemo-resistance of sCSC and sensitivity to CIK immunotherapy was confirmed in vivo. Our findings support CIK as an innovative, clinically explorable, approach to eradicate chemo-resistant sCSC implicated in tumor relapse.

Cell Polarity and Division Symmetry Analyses in Transformed Blood Cells

Cdc42 was originally discovered as a key regulator of bud site assembly and polarity in S. cerevisiae. Recent genetic studies have shown that the function of Cdc42 in regulating cell polarity appears highly conserved from budding yeast to humans. The role of Cdc42 in hematopoietic cell transformation and leukemia progression has been studied in an acute myeloid leukemia model using the MLL-AF9 oncogene-induced transformation and a Cdc42 conditional gene-targeted mouse model. Here we describe the leukemia cell polarity and division symmetry assays in the context of leukemia cell fate determination.

The role of interleukin-6-STAT3 signalling in glioblastoma

Glioblastoma is the most common type of malignant brain tumor among adults and is currently a non-curable disease due primarily to its highly invasive phenotype, and the lack of successful current therapies. Despite surgical resection and post-surgical treatment patients ultimately develop recurrence of the tumour. Several signalling molecules have been implicated in the development, progression and aggressiveness of glioblastoma. The present study reviewed the role of interleukin (IL)-6, a cytokine known to be important in activating several pro-oncogenic signaling pathways in glioblastoma. The current study particularly focused on the contribution of IL-6 in recurrent glioblastoma, with particular focus on glioblastoma stem cells and resistance to therapy.

MiR-205-5p inhibition by locked nucleic acids impairs metastatic potential of breast cancer cells

Mir-205 plays an important role in epithelial biogenesis and in mammary gland development but its role in cancer still remains controversial depending on the specific cellular context and target genes. We have previously reported that miR-205-5p is upregulated in breast cancer stem cells targeting ERBB pathway and leading to targeted therapy resistance. Here we show that miR-205-5p regulates tumorigenic properties of breast cancer cells, as well as epithelial to mesenchymal transition. Silencing this miRNA in breast cancer results in reduced tumor growth and metastatic spreading in mouse models. Moreover, we show that miR-205-5p knock-down can be obtained with the use of specific locked nucleic acids oligonucleotides in vivo suggesting a future potential use of this approach in therapy.

Methods to Analyze the Role of Progranulin (PGRN/GEP) on Cancer Stem Cell Features

Emerging evidence suggests that tumors are hierarchically organized with a distinct subpopulation called cancer stem cells (CSCs) lying at the apex of the hierarchy. These cells are not only responsible for tumor initiation and progression but also endowed with stem cell properties, including self-renewal, chemoresistance, and tumor initiation. Although existing therapies can initially eliminate the bulk population of tumor, the stem cell properties of CSCs enable them to survive and repopulate the tumor, resulting in disease relapse. Recently, our group has shown that progranulin (PGRN/GEP) defined a hepatic cancer stem cell subpopulation in hepatocellular carcinoma. This subpopulation demonstrated enhanced ability for colony and spheroid formation, chemoresistance, and tumor initiation. In this chapter, we describe the methods used to isolate the progranulin+ subpopulation and analyze their CSC properties.

Changes in mRNA/protein expression and signaling pathways in in vivo passaged mouse ovarian cancer cells

The cure rate for late stage epithelial ovarian cancer (EOC) has not significantly improved over several decades. New and more effective targets and treatment modalities are urgently needed. RNA-seq analyses of a syngeneic EOC cell pair, representing more and less aggressive tumor cells in vivo were conducted. Bioinformatics analyses of the RNA-seq data and biological signaling and function studies have identified new targets, such as ZIP4 in EOC. Many up-regulated tumor promoting signaling pathways have been identified which are mainly grouped into three cellular activities: 1) cell proliferation and apoptosis resistance; 2) cell skeleton and adhesion changes; and 3) carbohydrate metabolic reprograming. Unexpectedly, lipid metabolism has been the major down-regulated signaling pathway in the more aggressive EOC cells. In addition, we found that hypoxic responsive genes were at the center stage of regulation and detected functional changes were related to cancer stem cell-like activities. Moreover, our genetic, cellular, biochemical, and lipidomic analyses indicated that cells grown in 2D vs. 3D, or attached vs. suspended had dramatic changes. The important clinical implications of peritoneal cavity floating tumor cells are supported by the data proved in this work. Overall, the RNA-seq data provide a landscape of gene expression alterations during tumor progression.

Human colorectal cancer initiation is bidirectional, and cell growth, metabolic genes and transporter genes are early drivers of tumorigenesis

The role of stem cells in the development of solid tumors remains controversial. In colorectal cancers (CRC), this is complicated by the conflicting "top-down" or "bottom-up" hypotheses of cancer initiation. We profiled the expressions of genes from the top (T) and bottom (B) crypt fractions of normal-appearing human colonic mucosa (M) at least 20 cm away from the tumor as a baseline and compared this to the genes of matched mucosa adjacent to tumors (M_T) in twenty-three sporadic CRC patients. In thirteen patients, the genetic distance (M-M_T) between the B fractions is smaller than the distance between the T fractions, indicating that the expressions diverge further in the top fractions (B < T). In the remaining patients, the reverse effect is observed (B > T). Assuming that a greater genetic divergence in the top or bottom fractions indicates that position as the initiation site, it is thus equally likely that human CRC initiates from 'top-down' via de-differentiated colonocytes or 'bottom-up' via dysregulated intestinal stem cells. Dysregulated genes that persist until tumor stage are not limited to tumor suppressors or oncogenes but include metabolic and transporter genes such as CA7, PHLPP2, and AQP8.

Soft agar-based selection of spontaneously transformed rat prostate epithelial cells with highly tumorigenic characteristics

The critical molecular and cellular mechanisms involved in the development and progression of prostate cancer remain elusive. In this report, we demonstrate that normal rat prostate epithelial cells (PEC) undergo spontaneous transformation at high passage (p > 85) evidenced by the acquisition of anchorage independent growth when plated on soft agar and tumorigenicity when injected into immunodeficient mice. In addition, we also report the discovery of a minor subpopulation of spontaneously transformed PEC derived from high passage PEC with the ability to migrate through a layer of 1% agar and form expanding colonies on the underlying plastic substratum. Comparison of these soft agar invasive (SAI) cells with low (p < 35), mid (p36-84) and high passage (p > 85) PEC identified marked differences in cell morphology, proliferation and motility. The SAI subpopulation was more tumorigenic than the high passage anchorage independent cultures from which they were isolated, as manifested by a decreased latency period and an increase in the size of tumors arising in immunodeficient mice. In contrast, low and mid passage cells were unable to grow on soft agar and failed to form tumors when injected into immunodeficient mice. Screening with antibody-based signaling arrays identified several differences in the altered expression levels of signaling proteins between SAI-derived cells and low or high passage PEC, including the up-regulation of EGFR and MAPK-related signaling pathways in SAI-selected cells. In summary, these studies suggest that the SAI assay selects for a novel, highly tumorigenic subpopulation of transformed cells that may represent an early step in the progression of slow growing prostatic carcinomas into more rapidly growing and aggressive tumors.

Trends and outcomes of neoadjuvant radiotherapy compared with postoperative radiotherapy for malignant breast cancer

Background

Although neoadjuvant treatment has become the established approach for women with large primary tumors or locally advanced breast cancer for which immediate surgery is not the best approach, it may also stimulate cancer stem cell self-renewal and facilitate recurrence. We sought to determine the survival outcomes of preoperative radiotherapy (PRRT) compared with postoperative radiotherapy (PORT).

Materials and Methods

The Surveillance, Epidemiology, and End Results (SEER) registry was queried for patients who were diagnosed with breast cancer and underwent cancer-directed surgery. Survival analyses were performed with Cox proportional hazard regression for both overall survival (OS) and disease-specific survival (DSS), and 1:1 propensity score (PS) matching-adjusted competing risk analyses were conducted for DSS.

Results

We first identified 1,111,218 eligible patients in 18 registries from 1973 to 2013 and found that, outside of the Utah registry, sequence patterns other than PORT were rarely used. Thus, we next identified eligible patients registered in Utah (n = 7,042) from 1988 to 2007. The treatment trends shifted abruptly in 1988. Compared with the PORT group, the PRRT group showed significantly higher risks of overall mortality (absolute difference, 22.4%; P < 0.001), breast cancer-specific mortality (absolute difference, 8.6%; P < 0.001), and cardiovascular disease-specific mortality (absolute difference, 11.5%; P = 0.021). Survival differences in treatment sequences were correlated with stage.

Conclusions

Substantial shifts in treatment patterns for malignant breast cancer were identified in Utah. Compared with PORT, PRRT showed significantly worse outcomes. These results could inform future standardized options for radiation sequence with surgery and further clinical trials.

Phase II study of ruxolitinib, a selective JAK1/2 inhibitor, in patients with metastatic triple-negative breast cancer

Preclinical data support a role for the IL-6/JAK2/STAT3 signaling pathway in breast cancer. Ruxolitinib is an orally bioavailable receptor tyrosine inhibitor targeting JAK1 and JAK2. We evaluated the safety and efficacy of ruxolitinib in patients with metastatic breast cancer. This was a non-randomized phase II study enrolling patients with refractory, metastatic triple-negative breast cancer. The primary endpoint was objective response by RECIST 1.1. The study was designed to enroll patients whose archival tumor tissue was pSTAT3-positive (T-score >5) by central immunohistochemistry. pSTAT3 staining was available from 171 of 217 consented patients and pSTAT3 T-score was positive in 67/171 (39.2%) tumors, suggesting that JAK–STAT activation is frequent. Twenty-three patients including one patient with inflammatory breast cancer were enrolled. Ruxolitinib was well-tolerated with infrequent grade 3 or higher toxicities with fatigue as the most common toxicity. Among 21 patients who received at least one dose of protocol therapy, no objective responses were observed and the study was closed to further accrual. Pharmacodynamic analyses of baseline vs. cycle 2 biopsies suggest on-target activity, including a significant decrease in the proportion of pSTAT3⁺ cells in three patients with paired biopsies and downregulation of JAK–STAT target genes and signatures via transcriptional analyses of 11 total baseline and four metastatic biopsies. Immuno-FISH analyses demonstrate intratumoral heterogeneity of pSTAT3 and JAK2 amplification. Ruxolitinib, as a single agent, did not meet the primary efficacy endpoint in this refractory patient population despite evidence of on-target activity.

A drug that blocks the Janus tyrosine kinase (JAK) pathway offered no clinical benefit to women with triple-negative breast cancer. Ruxolitinib is an inhibitor of JAK1 and JAK2 that is approved to treat certain rare cancers of the blood and bone marrow, and there’s a good scientific evidence to think it might have anti-tumor effects against breast cancer as well. So a team led by N.U.L. from the Dana-Farber Cancer Institute in Boston, Massachusetts, USA, conducted a small phase II trial to evaluate ruxolitinib in women with refractory, metastatic, triple-negative disease whose tumors tested positive for high expression of pSTAT3, a protein in the same signaling pathway as JAK. Yet, despite the fact that pSTAT3 levels went down among the 21 women who received the drug, not a single one responded to the therapy.

Combination therapy in combating cancer

Combination therapy, a treatment modality that combines two or more therapeutic agents, is a cornerstone of cancer therapy. The amalgamation of anti-cancer drugs enhances efficacy compared to the mono-therapy approach because it targets key pathways in a characteristically synergistic or an additive manner. This approach potentially reduces drug resistance, while simultaneously providing therapeutic anti-cancer benefits, such as reducing tumour growth and metastatic potential, arresting mitotically active cells, reducing cancer stem cell populations, and inducing apoptosis. The 5-year survival rates for most metastatic cancers are still quite low, and the process of developing a new anti-cancer drug is costly and extremely time-consuming. Therefore, new strategies that target the survival pathways that provide efficient and effective results at an affordable cost are being considered. One such approach incorporates repurposing therapeutic agents initially used for the treatment of different diseases other than cancer. This approach is effective primarily when the FDA-approved agent targets similar pathways found in cancer. Because one of the drugs used in combination therapy is already FDA-approved, overall costs of combination therapy research are reduced. This increases cost efficiency of therapy, thereby benefiting the “medically underserved”. In addition, an approach that combines repurposed pharmaceutical agents with other therapeutics has shown promising results in mitigating tumour burden. In this systematic review, we discuss important pathways commonly targeted in cancer therapy. Furthermore, we also review important repurposed or primary anti-cancer agents that have gained popularity in clinical trials and research since 2012.

Cancer stem cell surface markers on normal stem cells

The cancer stem cell (CSC) hypothesis has captured the attention of many scientists. It is believed that elimination of CSCs could possibly eradicate the whole cancer. CSC surface markers provide molecular targeted therapies for various cancers, using therapeutic antibodies specific for the CSC surface markers. Various CSC surface markers have been identified and published. Interestingly, most of the markers used to identify CSCs are derived from surface markers present on human embryonic stem cells (hESCs) or adult stem cells. In this review, we classify the currently known 40 CSC surface markers into 3 different categories, in terms of their expression in hESCs, adult stem cells, and normal tissue cells. Approximately 73% of current CSC surface markers appear to be present on embryonic or adult stem cells, and they are rarely expressed on normal tissue cells. The remaining CSC surface markers are considerably expressed even in normal tissue cells, and some of them have been extensively validated as CSC surface markers by various research groups. We discuss the significance of the categorized CSC surface markers, and provide insight into why surface markers on hESCs are an attractive source to find novel surface markers on CSCs.

Biodistribution and Pharmacokinetic Evaluations of a Novel Taxoid DHA-SBT-1214 in an Oil-in-Water Nanoemulsion Formulation in Naïve and Tumor-Bearing Mice

PURPOSE

The main purpose of this study was to formulate an oil-in-water nanoemulsion of a next generation taxoid DHA-SBT-1214 and evaluate its biodistribution and pharmacokinetics.

METHODS

DHA-SBT-1214 was encapsulated in a fish oil containing nanoemulsion using a high pressure homogenization method. Following morphological characterization of the nanoemulsions, qualitative and quantitative biodistribution was evaluated in naïve and cancer stem cell-enriched PPT-2 human prostate tumor bearing mice.

RESULTS

DHA-SBT-1214 was successfully encapsulated up to 20 mg/ml in the nanoemulsion formulation and had an average oil droplet size of 200 nm. Using a DiR near infra-red dye encapsulated nanoemulsion, we have shown the delivery of nanoemulsion to mouse tumor region. By quantitative analysis, DHA-SBT-1214 encapsulated nanoemulsion demonstrated improved pharmacokinetic properties in plasma and different tissues as compared to its solution form. Furthermore, the nanoemulsions were stable and had slower in vitro drug release compared to its solution form.

CONCLUSIONS

The results from this study demonstrated effective encapsulation of the drug in a nanoemulsion and this nanoemulsion showed sustained plasma levels and enhanced tumor delivery relative to the solution form.

Cancer cell lines involving cancer stem cell populations respond to oxidative stress

Cancer cells may be more prone to the accumulation of reactive oxygen species (ROS) than normal cells; therefore increased oxidative stress can specifically kill cancer cells including cancer stem cells (CSCs). In order to generate oxidative stress in various cancer cell lines including A549, G361 and MCF-7, cultured cells were exposed to H2O2. Incubation of cancer cells with H2O2 results in concentration-dependent cell death in A549 and G361-7 cells, whereas MCF-7 cells showed higher sensitivity even at a lower H2O2 concentration. H2O2 treatment decreased the number of cells in G2/M phase and increased the number of apoptotic cells. Both CD24 negative/CD44 positive cells and CD146 positive cells were found to be present in all tested cancer cell lines, indicating that CSC populations may play role in the cellular response to oxidative stress. This study showed that inducing oxidative stress through ROS can offer a promising approach for anti-cancer therapy.

MiR-128 reverses the gefitinib resistance of the lung cancer stem cells by inhibiting the c-met/PI3K/AKT pathway

Gefitinib is a first line anti-tumor drug used for the treatment of patients with non-small cell lung cancer (NSCLC) harboring EGFR mutations. However, the drug resistance to gefitinib limits its clinical application. Here, we observed the CSCs of PC9 are obviously resistant to gefitinib compared with the non-CSCs. Furthermore, we found the gefitinib failed to suppress the PI3K/AKT pathway in the PC9-CSCs. Mechanically, we showed significant down-regulation of miR-128 in the PC9-CSCs compared with the non-CSCs. Overexpression of miR-128 significantly increased the sensitivity of PC9-CSCs to gefitinib-induced apoptosis. In addition, the gene of c-met was proved to be directly inhibited by miR-128. Enforced expression of c-met could "rescue" the miR-128 promoted apoptosis and cleavage of caspases in PC9-CSCs treated with gefitinib. Thus, these results indicate that the miR-128/c-met pathway enhances the gefitinib sensitivity of the lung cancer stem cells by suppressing the PI3K/AKT pathway.

HPV16 E6-E7 induces cancer stem-like cells phenotypes in esophageal squamous cell carcinoma through the activation of PI3K/Akt signaling pathway in vitro and in vivo

High-risk human papillomavirus (HPV), especially HPV16, correlates with cancerogenesis of human esophageal squamous cell carcinoma (ESCC) and we have reported that HPV16 related with a poor prognosis of ESCC patients in China. We aim to investigate the potential role and mechanism of HPV16 in ESCC development and progress. Our following researches demonstrated that ESCC cells which were stably transfected by HPV16 E6-E7 lentiviral vector showed a remarkable cancer stem-like cells (CSCs) phenotype, such as: migration, invasion, spherogenesis, high expression of CSCs marker in ESCC---p75NTR, chemoresistance, radioresistance, anti-apoptosis ability in vitro and cancerogenesis in vivo. HPV16 E6-E7 induced PI3K/Akt signaling pathway activation and this affect could be effectively inhibited by LY294002, a specific PI3K inhibitor. It was also indicated that the inhibition of PI3K/Akt signaling pathway by PI3K and Akt siRNA reverse the effect which induced by HPV16 E6-E7 in ESCC cells. Taken together, the present study demonstrates that HPV16 E6-E7 promotes CSCs phenotype in ESCC cells through the activation of PI3K/Akt signaling pathway. Targeting the PI3K/Akt signaling pathway in HPV16 positive tissues is an available therapeutic for ESCC patients.

ESM1 mediates NGFR-induced invasion and metastasis in murine oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a highly invasive and metastatic malignancy. The nerve growth factor receptor (NGFR) has been observed to be expressed on a subset of cells in OSCC, and NGFR⁺ cells have greater tumor-initiating capacity in vivo. Further, inhibition of NGFR reduces tumor growth, indicating a functional role of this receptor; however, the mechanisms by which NGFR confers enhanced tumor formation are not known. Here, we used an established murine model of OSCC and gene expression array analysis to identify ESM1 as a downstream target gene of NGFR, critical for tumor invasion and metastasis. ESM1 encodes a protein called endocan, which has the property of regulating proliferation, differentiation, migration, and adhesion of different cell types. Incubation of NGFR⁺ murine OSCC cells with nerve growth factor resulted in increased expression of ESM1. Importantly, ESM1 overexpression conferred an enhanced migratory, invasive, and metastatic phenotype, similar to what has been correlated with NGFR expression. Conversely, shRNA knockdown of ESM1 in NGFR overexpressing OSCC cells abrogated the tumor growth kinetics and the invasive and metastatic properties associated with NGFR. Together, our data indicate that NGFR plays an important role in the pathogenesis and progression of OSCC via regulation of ESM1.

Inhibition of HAX-1 by miR-125a reverses cisplatin resistance in laryngeal cancer stem cells

Chemoresistance is a major obstacle in chemotherapy of laryngeal carcinoma. Recently, studies indicate that cancer stem cells are responsible for chemotherapy failure. In addition, microRNAs play important roles in tumor initiation, development and multidrug resistance. In the present study, we found that the expression of microRNA-125a was decreased in laryngeal carcinoma tissues and Hep-2 laryngeal cancer stem cells (Hep-2-CSCs). MicroRNA-125a gain-of-function significantly increased the sensitivity of Hep-2-CSCs to cisplatin in vitro and in vivo. Combination with microRNA-125a mimics can decrease the half maximal inhibitory concentration of Hep-2-CSCs to cisplatin. Mechanically, we found that microRNA-125a reverses cisplatin resistance in Hep-2-CSCs by targeting Hematopoietic cell-specific protein 1-associated protein X-1 (HAX-1). Inhibition of HAX-1 by microRNA-125a significantly promotes the cisplatin-induced apoptosis in Hep-2-CSCs through mitochondrial pathway. In addition, multidrug resistance of Hep-2-CSCs to vincristine, etoposide and doxorubicin was greatly improved after the cells were transfected with microRNA-125a mimics. These dates strongly suggested the promotion of microRNA-125a/HAX-1 axis on chemotherapy of laryngeal carcinoma.

Physiological functions of FBW7 in cancer and metabolism

FBW7 is one of the most well characterized F-box proteins that serve as substrate recognition subunits of SCF (Skp1-Cullin 1-F-box proteins) E3 ubiquitin ligase complexes. SCF^FBW7 plays key roles in regulating cell cycle progression, differentiation, and stem cell maintenance largely through targeting a broad range of oncogenic substrates for proteasome-dependent degradation. The identification of an increasing number of FBW7 substrates for ubiquitination, and intensive in vitro and in vivo studies have revealed a network of signaling components controlled by FBW7 that contributes to metabolic regulation as well as its tumor suppressor role. Here we mainly focus on recent findings that highlight a critical role for FBW7 in cancer and metabolism.

HER2 Overexpression Triggers an IL1α Proinflammatory Circuit to Drive Tumorigenesis and Promote Chemotherapy Resistance

Systemic inflammation in breast cancer correlates with poor prognosis, but the molecular underpinnings of this connection are not well understood. In this study, we explored the relationship between HER2 overexpression, inflammation, and expansion of the mammary stem/progenitor and cancer stem-like cell (CSC) population in breast cancer. HER2-positive epithelial cells initiated and sustained an inflammatory milieu needed to promote tumorigenesis. HER2 induced a feedforward activation loop of IL1α and IL6 that stimulated NFκB and STAT3 pathways for generation and maintenance of breast CSC. In mice, Il1a genetic deficiency delayed MMTV-Her2-induced tumorigenesis and reduced inflammatory cytokine expression as well as CSC in primary tumors. In clinical specimens of human breast tumor tissues, tissue microarray analysis revealed a strong positive correlation between IL1α/IL6 expression and CSC-positive phenotype. Pharmacologic blockade of IL1α signaling reduced the CSC population and improved chemotherapeutic efficacy. Our findings suggest new therapeutic or prevention strategies for HER2-positive breast cancers.Significance: IL1α signaling driven by HER2 promotes chronic inflammation needed to support cancer stem-like cell maintenance in HER2-positive breast cancers. Cancer Res; 78(8); 2040-51. ©2018 AACR.

Oncolytic vaccinia virus inhibits human hepatocellular carcinoma MHCC97-H cell proliferation via endoplasmic reticulum stress, autophagy and Wnt pathways

BACKGROUND

Hepatocellular carcinoma (HCC) is a highly lethal malignancy. Vaccinia virus (VV) possessed many inherent advantages with respect to being engineered as a vector for cancer gene therapy, although the mechanism of action remains to be explored further.

METHODS

We constructed a thymidine kinase gene insertional inactivated VV, named VV-Onco, and then tested its effects on cell viability, apoptosis and colony formation ability in a highly metastatic human hepatocellular carcinoma cell line MHCC97-H, and also investigated the potential cell signal pathways involved in this action.

RESULTS

VV-Onco induced strong cytotoxicity and apoptosis and also inhibited the colony formation of MHCC97-H cells. The tumor cell apoptosis induced by VV-Onco is likely mediated via endoplasmic reticulum stress, autophagy and Wnt signaling pathways. The downregulation of survivin and c-Myc may also play a role in VV-Onco induced cell death.

CONCLUSIONS

The results of the present study provide new insights into the mechanisms of VV-induced tumor cell death. The engineered recombinant VV containing optimized therapeutic transgenes may represent a new avenue for cancer gene therapy. Copyright © 2016 John Wiley & Sons, Ltd.

Intratumoral heterogeneity: pathways to treatment resistance and relapse in human glioblastoma

Intratumoral heterogeneity (ITH) has increasingly being described for multiple cancers as the root cause of therapy resistance. Recent studies have started to explore the scope of ITH in glioblastoma (GBM), a highly aggressive and fatal form of brain tumor, to explain its inevitable therapy resistance and disease relapse. In this review, we detail the emerging data that explores the extensive genetic, cellular and functional ITH present in GBM. We discuss current experimental models of human GBM recurrence and suggest harnessing new technologies (CRISPR-Cas9 screening, CyTOF, cellular barcoding, single cell analysis) to delineate GBM ITH and identify treatment-refractory cell populations, thus opening new therapeutic windows. We will also explore why current therapeutics have failed in clinical trials and how ITH can inform us on developing empiric therapies for the treatment of recurrent GBM.