Bone morphogenetic proteins regulate tumorigenicity in human glioblastoma stem cells

Delineating the glioblastoma stemness by genes involved in cytoskeletal rearrangements and metabolic alterations

Literature data on glioblastoma ongoingly underline the link between metabolism and cancer stemness, the latter is one responsible for potentiating the resistance to treatment, inter alia due to increased invasiveness. In recent years, glioblastoma stemness research has bashfully introduced a key aspect of cytoskeletal rearrangements, whereas the impact of the cytoskeleton on invasiveness is well known. Although non-stem glioblastoma cells are less invasive than glioblastoma stem cells (GSCs), these cells also acquire stemness with greater ease if characterized as invasive cells and not tumor core cells. This suggests that glioblastoma stemness should be further investigated for any phenomena related to the cytoskeleton and metabolism, as they may provide new invasion-related insights. Previously, we proved that interplay between metabolism and cytoskeleton existed in glioblastoma. Despite searching for cytoskeleton-related processes in which the investigated genes might have been involved, not only did we stumble across the relation to metabolism but also reported genes that were found to be implicated in stemness. Thus, dedicated research on these genes in GSCs seems justifiable and might reveal novel directions and/or biomarkers that could be utilized in the future. Herein, we review the previously identified cytoskeleton/metabolism-related genes through the prism of glioblastoma stemness.

Nucleic acid drug vectors for diagnosis and treatment of brain diseases

Nucleic acid drugs have the advantages of rich target selection, simple in design, good and enduring effect. They have been demonstrated to have irreplaceable superiority in brain disease treatment, while vectors are a decisive factor in therapeutic efficacy. Strict physiological barriers, such as degradation and clearance in circulation, blood-brain barrier, cellular uptake, endosome/lysosome barriers, release, obstruct the delivery of nucleic acid drugs to the brain by the vectors. Nucleic acid drugs against a single target are inefficient in treating brain diseases of complex pathogenesis. Differences between individual patients lead to severe uncertainties in brain disease treatment with nucleic acid drugs. In this Review, we briefly summarize the classification of nucleic acid drugs. Next, we discuss physiological barriers during drug delivery and universal coping strategies and introduce the application methods of these universal strategies to nucleic acid drug vectors. Subsequently, we explore nucleic acid drug-based multidrug regimens for the combination treatment of brain diseases and the construction of the corresponding vectors. In the following, we address the feasibility of patient stratification and personalized therapy through diagnostic information from medical imaging and the manner of introducing contrast agents into vectors. Finally, we take a perspective on the future feasibility and remaining challenges of vector-based integrated diagnosis and gene therapy for brain diseases.

An immune and epithelial-mesenchymal transition-related risk model and immunotherapy strategy for grade II and III gliomas

Grade II and III gliomas are heterogeneous and aggressive diseases. More efficient prognosis models and treatment methods are needed. This study aims to construct a new risk model and propose a new strategy for grade II and III gliomas. The data were downloaded from The Cancer Genome Atlas (TCGA), the Gene Expression Omnibus (GEO), gene set enrichment analysis (GSEA), and the EMTome website for analysis. The Human Cell Landscape website and the Genomics of Drug Sensitivity in Cancer website were used for single-cell analysis and drug susceptibility analysis. Gene set enrichment analysis, gene function enrichment analysis, univariate and multivariate Cox regression analyses, Pearson's correlation analysis, log-rank test, Kaplan-Meier survival analysis, and ROC analysis were performed. We constructed an immune-related prognostic model associated with the isocitrate dehydrogenase 1 (IDH1) mutation status. By analyzing the immune microenvironment of patients with different risk scores, we found that high-risk patients were more likely to have an inflammatory immune microenvironment and a higher programmed death ligand-1 (PD-L1) expression level. Epithelial-mesenchymal transition (EMT)-related gene sets were significantly enriched in the high-risk group, and the epithelial-mesenchymal transition phenotype was associated with a decrease in CD8⁺ T cells and an increase in M2 macrophages. Transforming growth factor-β (TGF-β) signaling was the most important signaling in inducing epithelial-mesenchymal transition, and TGFB1/TGFBR1 was correlated with an increase in CD8⁺ T cytopenia and M2 macrophages. Survival analysis showed that simultaneous low expression of TGFBR1 and PD-L1 had better survival results. Through single-cell analysis, we found that TGFB1 is closely related to microglia and macrophages, especially M2 macrophages. Finally, we discussed the sensitivity of TGFB1 inhibitors in gliomas using cell line susceptibility data. These results demonstrated a potential immunotherapy strategy in combination with the TGFB1/TGFBR1 inhibitor and PD-1/PD-L1 inhibitor for grade II and III gliomas.

Glioma stem cells and neural stem cells respond differently to BMP4 signaling

Malignant glioma is a highly heterogeneous and invasive primary brain tumor characterized by high recurrence rates, resistance to combined therapy, and dismal prognosis. Glioma stem cells (GSCs) are likely responsible for tumor progression, resistance to therapy, recurrence, and poor prognosis owing to their high self-renewal and tumorigenic potential. As a family member of BMP signaling, bone morphogenetic protein4 (BMP4) has been reported to induce the differentiation of GSCs and neural stem cells (NSCs). However, the molecular mechanisms underlying the BMP4-mediated effects in these two cell types are unclear. In this study, we treated hGSCs and hNSCs with BMP4 and compared the phenotypic and transcriptional changes between these two cell types. Phenotypically, we found that the growth of hGSCs was greatly inhibited by BMP4, but the same treatment only increased the cell size of hNSCs. While the RNA sequencing results showed that BMP4 treatment evoked significantly transcriptional changes in both hGSCs and hNSCs, the profiles of differentially expressed genes were distinct between the two groups. A gene set that specifically targeted the proliferation and differentiation of hGSCs but not hNSCs was enriched and then validated in hGSC culture. Our results suggested that hGSCs and hNSCs responded differently to BMP4 stimulation. Understanding and investigating different responses between hGSCs and hNSCs will benefit finding partner factors working together with BMP4 to further suppress GSCs proliferation and stemness without disturbing NSCs.

A Novel Role of BIRC3 in Stemness Reprogramming of Glioblastoma

Stemness reprogramming remains a largely unaddressed principal cause of lethality in glioblastoma (GBM). It is therefore of utmost importance to identify and target mechanisms that are essential for GBM stemness and self-renewal. Previously, we implicated BIRC3 as an essential mediator of therapeutic resistance and survival adaptation in GBM. In this study, we present novel evidence that BIRC3 has an essential noncanonical role in GBM self-renewal and stemness reprogramming. We demonstrate that BIRC3 drives stemness reprogramming of human GBM cell lines, mouse GBM cell lines and patient-derived GBM stem cells (GSCs) through regulation of BMP4 signaling axis. Specifically, BIRC3 induces stemness reprogramming in GBM through downstream inactivation of BMP4 signaling. RNA-Seq interrogation of the stemness reprogramming hypoxic (pseudopalisading necrosis and perinecrosis) niche in GBM patient tissues further validated the high BIRC3/low BMP4 expression correlation. BIRC3 knockout upregulated BMP4 expression and prevented stemness reprogramming of GBM models. Furthermore, siRNA silencing of BMP4 restored stemness reprogramming of BIRC3 knockout in GBM models. In vivo silencing of BIRC3 suppressed tumor initiation and progression in GBM orthotopic intracranial xenografts. The stemness reprograming of both GSCs and non-GSCs populations highlights the impact of BIRC3 on intra-tumoral cellular heterogeneity GBM. Our study has identified a novel function of BIRC3 that can be targeted to reverse stemness programming of GBM.

ANLN Enhances Triple-Negative Breast Cancer Stemness Through TWIST1 and BMP2 and Promotes its Spheroid Growth

ANLN is frequently upregulated in triple-negative breast cancer (TNBC) and its high expression in tumors are significantly associated with poor survival and recurrence, thereby it has been proposed to function as a prognostic marker for breast cancer. However, the specific function and molecular mechanisms by which ANLN promotes TNBC tumorigenesis remain elusive. Using multiomic profiling, we recently uncovered ANLN as a TNBC-specific gene driven by super-enhancer. Here, by Crispr/Cas9 editing, we showed that knockout of ANLN inhibits spheroid growth of TNBC. Interestingly, its effect on cell proliferation in 2D cultures is minimal. ANLN depletion inhibits mammosphere formation and clonogenicity potently, suggesting its important function in regulating cancer stem cells (CSCs). We screened a panel of stem cell-related genes and uncovered several CSC genes regulated by ANLN. We further identify TWIST1 and BMP2 as essential genes that mediate ANLN’s function in stemness but not spheroid growth. These findings may contribute to search for effective targeted therapies to treat TNBC.

The Role of Neurodevelopmental Pathways in Brain Tumors

Disruptions to developmental cell signaling pathways and transcriptional cascades have been implicated in tumor initiation, maintenance and progression. Resurgence of aberrant neurodevelopmental programs in the context of brain tumors highlights the numerous parallels that exist between developmental and oncologic mechanisms. A deeper understanding of how dysregulated developmental factors contribute to brain tumor oncogenesis and disease progression will help to identify potential therapeutic targets for these malignancies. In this review, we summarize the current literature concerning developmental signaling cascades and neurodevelopmentally-regulated transcriptional programs. We also examine their respective contributions towards tumor initiation, maintenance, and progression in both pediatric and adult brain tumors and highlight relevant differentiation therapies and putative candidates for prospective treatments.

Single-cell analyses reveal YAP/TAZ as regulators of stemness and cell plasticity in Glioblastoma

Glioblastoma (GBM) is a devastating human malignancy. GBM stem-like cells (GSCs) drive tumor initiation and progression. Yet, the molecular determinants defining GSCs in their native state in patients remain poorly understood. Here we used single cell datasets and identified GSCs at the apex of the differentiation hierarchy of GBM. By reconstructing the GSCs' regulatory network, we identified the YAP/TAZ coactivators as master regulators of this cell state, irrespectively of GBM subtypes. YAP/TAZ are required to install GSC properties in primary cells downstream of multiple oncogenic lesions, and required for tumor initiation and maintenance in vivo in different mouse and human GBM models. YAP/TAZ act as main roadblock of GSC differentiation and their inhibition irreversibly lock differentiated GBM cells into a non-tumorigenic state, preventing plasticity and regeneration of GSC-like cells. Thus, GSC identity is linked to a key molecular hub integrating genetics and microenvironmental inputs within the multifaceted biology of GBM.

Advances in histone deacetylase inhibitors in targeting glioblastoma stem cells

Glioblastoma multiforme (GBM) is a lethal grade IV glioma (WHO classification) and widely prevalent primary brain tumor in adults. GBM tumors harbor cellular heterogeneity with the presence of a small subpopulation of tumor cells, described as GBM cancer stem cells (CSCs) that pose resistance to standard anticancer regimens and eventually mediate aggressive relapse or intractable progressive GBM. Existing conventional anticancer therapies for GBM do not target GBM stem cells and are mostly palliative; therefore, exploration of new strategies to target stem cells of GBM has to be prioritized for the development of effective GBM therapy. Recent developments in the understanding of GBM pathophysiology demonstrated dysregulation of epigenetic mechanisms along with the genetic changes in GBM CSCs. Altered expression/activity of key epigenetic regulators, especially histone deacetylases (HDACs) in GBM stem cells has been associated with poor prognosis; inhibiting the activity of HDACs using histone deacetylase inhibitors (HDACi) has been promising as mono-therapeutic in targeting GBM and in sensitizing GBM stem cells to an existing anticancer regimen. Here, we review the development of pan/selective HDACi as potential anticancer agents in targeting the stem cells of glioblastoma as a mono or combination therapy.

BMP4 promotes hepatocellular carcinoma proliferation by autophagy activation through JNK1-mediated Bcl-2 phosphorylation

Background

Autophagy is a conserved catabolic process with complicated roles in tumor development. Bone morphogenetic protein 4 (BMP4), a member of the transforming growth factor (TGF-β) family of regulatory proteins, plays a crucial role in human malignancies. However, whether BMP4 contributes to the regulation of autophagy in hepatocellular carcinoma (HCC) progression remains elusive.

Methods

Functional analysis of BMP4 on HCC proliferation and autophagy was performed both in vitro and in vivo in HepG2 and HCCLM3 cells. Autophagic activity was estimated by Western blot for autophagic marker proteins and by transmission electron microscopy (TEM). Transfection of mRFP-GFP-LC3 adenovirus was applied to observe autophagic flux and high content screening was used for quantification. The signaling pathway of BMP4-regulated HCC proliferation and autophagy was investigated by Western blot.

Results

BMP4 treatment promoted HCC cells proliferation and induced autophagy. The in vivo xenograft model supported that BMP4 overexpression promoted the growth of HCC cells and autophagy induction while BMP4 knockdown exerted the opposite effect. 3-MA pre-treatment or knockdown of Beclin-1 (BECN1) blocked HCC autophagy by decreasing the expression of LC3-II and subsequently attenuated BMP4-induced autophagy and cells proliferation enhanced by BMP4 in vitro and in vivo. Mechanistic study revealed that the induction of autophagy by BMP4 was mediated through activating the JNK1/Bcl2 pathway. Furthermore, the JNK1 inhibitor and knockdown of JNK1 could attenuate autophagy induced by BMP4 and eliminated BMP4-promoted HCC cells growth.

Conclusions

BMP4 promoted HCC proliferation by autophagy activation through JNK1/Bcl-2 signaling.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0828-x) contains supplementary material, which is available to authorized users.

The TGFβ-signaling pathway and colorectal cancer: associations between dysregulated genes and miRNAs

Background

The TGFβ-signaling pathway plays an important role in the pathogenesis of colorectal cancer (CRC). Loss of function of several genes within this pathway, such as bone morphogenetic proteins (BMPs) have been seen as key events in CRC progression.

Methods

In this study we comprehensively evaluate differential gene expression (RNASeq) of 81 genes in the TGFβ-signaling pathway and evaluate how dysregulated genes are associated with miRNA expression (Agilent Human miRNA Microarray V19.0). We utilize paired carcinoma and normal tissue from 217 CRC cases. We evaluate the associations between differentially expressed genes and miRNAs and sex, age, disease stage, and survival months.

Results

Thirteen genes were significantly downregulated and 14 were significantly upregulated after considering fold change (FC) of > 1.50 or < 0.67 and multiple comparison adjustment. Bone morphogenetic protein genes BMP5, BMP6, and BMP2 and growth differentiation factor GDF7 were downregulated. BMP4, BMP7, INHBA (Inhibin beta A), TGFBR1, TGFB2, TGIF1, TGIF2, and TFDP1 were upregulated. In general, genes with the greatest dysregulation, such as BMP5 (FC 0.17, BMP6 (FC 0.25), BMP2 (FC 0.32), CDKN2B (FC 0.32), MYC (FC 3.70), BMP7 (FC 4.17), and INHBA (FC 9.34) showed dysregulation in the majority of the population (84.3, 77.4, 81.1, 80.2, 82.0, 51.2, and 75.1% respectively). Four genes, TGFBR2, ID4, ID1, and PITX2, were un-associated or slightly upregulated in microsatellite-stable (MSS) tumors while downregulated in microsatellite-unstable (MSI) tumors. Eight dysregulated genes were associated with miRNA differential expression. E2F5 and THBS1 were associated with one or two miRNAs; RBL1, TGFBR1, TGIF2, and INHBA were associated with seven or more miRNAs with multiple seed-region matches. Evaluation of the joint effects of mRNA:miRNA identified interactions that were stronger in more advanced disease stages and varied by survival months.

Conclusion

These data support an interaction between miRNAs and genes in the TGFβ-signaling pathway in association with CRC risk. These interactions are associated with unique clinical characteristics that may provide targets for further investigations.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1566-8) contains supplementary material, which is available to authorized users.

The developmental origin of brain tumours: a cellular and molecular framework

The development of the nervous system relies on the coordinated regulation of stem cell self-renewal and differentiation. The discovery that brain tumours contain a subpopulation of cells with stem/progenitor characteristics that are capable of sustaining tumour growth has emphasized the importance of understanding the cellular dynamics and the molecular pathways regulating neural stem cell behaviour. By focusing on recent work on glioma and medulloblastoma, we review how lineage tracing contributed to dissecting the embryonic origin of brain tumours and how lineage-specific mechanisms that regulate stem cell behaviour in the embryo may be subverted in cancer to achieve uncontrolled proliferation and suppression of differentiation.

Summary: Lineage-tracing work in glioma and medulloblastoma reveals similarities between neuronal development and brain tumours, identifying potential new therapeutic avenues that exploit vulnerabilities in tumour growth patterns.

Comparison of the use of rhBMP-7 versus iliac crest autograft in single-level lumbar fusion: a meta-analysis of randomized controlled trials

The aim of this study was to evaluate the safety and clinical effectiveness of rhBMP-7 (or osteogenic protein-1) versus that of autogenous iliac crest bone graft (ICBG) in single-level posterolateral fusion (PLF) of the lumbar spine. A systematic search of all articles published through July 1, 2016 was conducted in databases such as PubMed, EMBASE, Scopus, and the Cochrane Collaboration Library. Randomized controlled trials (RCTs) that compared rhBMP-7 with ICBG for the treatment of single-level degenerative spondylolisthesis, provided the fusion rate, clinical success rate, safety and adverse events report, operation time, and hospital stay durations as the outcome were assessed. As a result, a total of five RCTs involving 539 patients met the inclusion criteria. The outcomes of subgroup analysis demonstrated that when compared with autogenous ICBG, rhBMP-7 appear to yield lower fusion rates in instrumented posterolateral fusion patients (RR = 0.76, 95% CI [0.60, 0.98], P = 0.03), despite the test for overall fusion rates suggested that there was no significant difference between the two groups (RR = 0.89, 95% CI [0.78, 1.02], P = 0.09). Patients treated with OP-1 had shorter operation times versus those treated with ICBG (WMD = -16.70,95% CI [-25.83, -7.57], P = 0.0003). Additionally, the outcomes demonstrated a lack of significant differences between rhBMP-7 and ICBG in terms of clinical success of ODI, overall adverse events, revision rates and duration of hospitalization. In conclusion, with the exception of reducing the operation time, our review suggests that the use of the rhBMP-7 instead of ICBG produce no any additional beneficial effect on the fusion rates, clinical success of ODI, overall adverse events, revision rates and duration of hospitalization in single level PLF. On the contrary, it appeared to yield lower fusion rate in the instrumented posterolateral fusion patients and cannot be recommended as an effective tool for this set of patients.

DOCK4 promotes loss of proliferation in glioblastoma progenitor cells through nuclear beta-catenin accumulation and subsequent miR-302-367 cluster expression

Glioblastomas (GBM) are lethal primitive brain tumours characterized by a strong intra-tumour heterogeneity. We observed in GBM tissues the coexistence of functionally divergent micro-territories either enriched in more differentiated and non-mitotic cells or in mitotic undifferentiated OLIG2 positive cells while sharing similar genomic abnormalities. Understanding the formation of such functionally divergent micro-territories in glioblastomas (GBM) is essential to comprehend GBM biogenesis, plasticity and to develop therapies. Here we report an unexpected anti-proliferative role of beta-catenin in non-mitotic differentiated GBM cells. By cell type specific stimulation of miR-302, which directly represses cyclin D1 and stemness features, beta-catenin is capable to change its known proliferative function. Nuclear beta-catenin accumulation in non-mitotic cells is due to a feed forward mechanism between DOCK4 and beta-catenin, allowed by increased GSK3-beta activity. DOCK4 over expression suppresses selfrenewal and tumorigenicity of GBM stem-like cells. Accordingly in the frame of GBM median of survival, increased level of DOCK4 predicts improved patient survival.

Genetic variants in the TGFβ-signaling pathway influence expression of miRNAs in colon and rectal normal mucosa and tumor tissue

The TGF-β signaling pathway is involved in regulation of cell growth, angiogenesis, and metastasis. We test the hypothesis that genetic variation in the TGF-β signaling pathway alters miRNA expression.We use data from 1188 colorectal cancer cases to evaluate associations between 80 SNPs in 21 genes.Seven variants eIF4E rs12498533, NFκB1 rs230510, TGFB1 rs4803455, TGFBR1 rs1571590 and rs6478974, SMAD3 rs3743343, and RUNX1 rs8134179 were associated with expression level of miRNAs in normal colorectal mucosa. RUNX2 rs12333172 and BMPR1B rs13134042 were associated with miRNAs in normal colon mucosa; eIF4EBP3 rs250425, SMAD3 rs12904944, SMAD7 rs3736242, and PTEN rs532678 were associated with miRNA expression in normal rectal mucosa. Evaluation of the differential expression between carcinoma and normal mucosa showed that SMAD3 rs12708491 and rs2414937, NFκB1 rs230510 and rs3821958, and RUNX3 rs6672420 were associated with several miRNAs for colorectal carcinoma. Evaluation of site-specific differential miRNA expression showed that BMPR1B rs2120834, BMPR2 rs2228545, and eIF4EBP3 rs250425 were associated with differential miRNA expression in colon tissue and SMAD3 rs12901071, rs1498506, and rs2414937, BMPR2 rs2228545, and RUNX2 rs2819854, altered differential miRNA expression in rectal tissue.These data support the importance of the TGF-β signaling pathway to the carcinogenic process, possibly through their influence on miRNA expression levels.

Metabotropic glutamate receptors as a new therapeutic target for malignant gliomas

Metabotropic glutamate receptors (mGluR) are predominantly involved in maintenance of cellular homeostasis of central nervous system. However, evidences have suggested other roles of mGluR in human tumors. Aberrant mGluR signaling has been shown to participate in transformation and maintenance of various cancer types, including malignant brain tumors. This review intends to summarize recent findings regarding the involvement of mGluR-mediated intracellular signaling pathways in progression, aggressiveness, and recurrence of malignant gliomas, mainly glioblastomas (GBM), highlighting the potential therapeutic applications of mGluR ligands. In addition to the growing number of studies reporting mGluR gene or protein expression in glioma samples (resections, lineages, and primary cultures), pharmacological blockade in vitro of mGluR1 and mGluR3 by selective ligands has been shown to be anti-proliferative and anti-migratory, decreasing activation of MAPK and PI3K pathways. In addition, mGluR3 antagonists promoted astroglial differentiation of GBM cells and also enabled cytotoxic action of temozolomide (TMZ). mGluR3-dependent TMZ toxicity was supported by increasing levels of MGMT transcripts through an intracellular signaling pathway that sequentially involves PI3K and NF-κB. Further, continuous pharmacological blockade of mGluR1 and mGluR3 have been shown to reduced growth of GBM tumor in two independent in vivo xenograft models. In parallel, low levels of mGluR3 mRNA in GBM resections may be a predictor for long survival rate of patients. Since several Phase I, II and III clinical trials are being performed using group I and II mGluR modulators, there is a strong scientifically-based rationale for testing mGluR antagonists as an adjuvant therapy for malignant brain tumors.

Therapeutic Potential for Bone Morphogenetic Protein 4 in Human Malignant Glioma

Human glioma, in particular, malignant forms such as glioblastoma exhibit dismal survival rates despite advances in treatment strategies. A population of glioma cells with stem-like features, glioma cancer stem-like cells (GCSCs), contribute to renewal and maintenance of the tumor cell population and appear responsible for chemotherapeutic and radiation resistance. Bone morphogenetic protein 4 (BMP4), drives differentiation of GCSCs and thus improves therapeutic efficacy. Based on this observation it is imperative that the clinical merits of BMP4 in treating human gliomas should be addressed. This article reviews BMP4 signaling in central nervous system development and in glioma tumorigenesis, and the potential of this molecule as a treatment target in human gliomas. Further work needs to be done to determine if distinct lineages of GCSCs, associated with different glioma sub-classifications, proneural, neural, classical and mesenchymal, differ in responsiveness to BMP4 treatment. Additionally, interaction among BMP4 and cell matrix, tumor-vascular molecules and microglial immune cells also needs to be investigated, as this will enhance our knowledge about the role of BMP4 in human glioma and lead to the identification and/or development of novel therapeutic approaches that improve treatment outcomes of these devastating tumors.

Cancer Stem Cells: Cellular Plasticity, Niche, and its Clinical Relevance

Cancer handles an estimated 7.6 million deaths worldwide per annum. A recent theory focuses on the role Cancer Stem Cells (CSCs) in driving tumorigenesis and disease progression. This theory hypothesizes that a population of the tumor cell with similar functional and phenotypic characteristics as normal tissue stem cells are responsible for formation and advancement of many human cancers. The CSCs subpopulation can differentiate into non-CSC tumor cells and promote phenotypic and functional heterogeneity within the tumor. The presence of CSCs has been reported in a number of human cancers including blood, breast, brain, colon, lung, pancreas prostate and liver. Although the origin of CSCs remains a mystery, recent reports suggest that the phenotypic characteristics of CSCs may be plastic and are influenced by the microenvironment specific for the individual tumor. Such factors unique to each tumor preserve the dynamic balance between CSCs to non-CSCs cell fate, as well as maintain the proper equilibrium. Alternating such equilibrium via dedifferentiation can result in aggressiveness, as CSCs are considered to be more resistant to the conventional cancer treatments of chemotherapy and radiation. Understanding how the tumoral microenvironment affects the plasticity driven CSC niche will be critical for developing a more effective treatment for cancer by eliminating its aggressive and recurring nature that now is believed to be perpetuated by CSCs.

PCM1 Depletion Inhibits Glioblastoma Cell Ciliogenesis and Increases Cell Death and Sensitivity to Temozolomide

A better understanding of the molecules implicated in the growth and survival of glioblastoma (GBM) cells and their response to temozolomide (TMZ), the standard-of-care chemotherapeutic agent, is necessary for the development of new therapies that would improve the outcome of current GBM treatments. In this study, we characterize the role of pericentriolar material 1 (PCM1), a component of centriolar satellites surrounding centrosomes, in GBM cell proliferation and sensitivity to genotoxic agents such as TMZ. We show that PCM1 is expressed around centrioles and ciliary basal bodies in patient GBM biopsies and derived cell lines and that its localization is dynamic throughout the cell cycle. To test whether PCM1 mediates GBM cell proliferation and/or response to TMZ, we used CRISPR/Cas9 genome editing to generate primary GBM cell lines depleted of PCM1. These PCM1-depleted cells displayed reduced AZI1 satellite protein localization and significantly decreased proliferation, which was attributable to increased apoptotic cell death. Furthermore, PCM1-depleted lines were more sensitive to TMZ toxicity than control lines. The increase in TMZ sensitivity may be partly due to the reduced ability of PCM1-depleted cells to form primary cilia, as depletion of KIF3A also ablated GBM cells' ciliogenesis and increased their sensitivity to TMZ while preserving PCM1 localization. In addition, the co-depletion of KIF3A and PCM1 did not have any additive effect on TMZ sensitivity. Together, our data suggest that PCM1 plays multiple roles in GBM pathogenesis and that associated pathways could be targeted to augment current or future anti-GBM therapies.

Non-virally engineered human adipose mesenchymal stem cells produce BMP4, target brain tumors, and extend survival

There is a need for enabling non-viral nanobiotechnology to allow safe and effective gene therapy and cell therapy, which can be utilized to treat devastating diseases such as brain cancer. Human adipose-derived mesenchymal stem cells (hAMSCs) display high anti-glioma tropism and represent a promising delivery vehicle for targeted brain tumor therapy. In this study, we demonstrate that non-viral, biodegradable polymeric nanoparticles (NPs) can be used to engineer hAMSCs with higher efficacy (75% of cells) than leading commercially available reagents and high cell viability. To accomplish this, we engineered a poly(beta-amino ester) (PBAE) polymer structure to transfect hAMSCs with significantly higher efficacy than Lipofectamine™ 2000. We then assessed the ability of NP-engineered hAMSCs to deliver bone morphogenetic protein 4 (BMP4), which has been shown to have a novel therapeutic effect by targeting human brain tumor initiating cells (BTIC), a source of cancer recurrence, in a human primary malignant glioma model. We demonstrated that hAMSCs genetically engineered with polymeric nanoparticles containing BMP4 plasmid DNA (BMP4/NP-hAMSCs) secrete BMP4 growth factor while maintaining their multipotency and preserving their migration and invasion capacities. We also showed that this approach can overcome a central challenge for brain therapeutics, overcoming the blood brain barrier, by demonstrating that NP-engineered hAMSCs can migrate to the brain and penetrate the brain tumor after both intranasal and systemic intravenous administration. Critically, athymic rats bearing human primary BTIC-derived tumors and treated intranasally with BMP4/NP-hAMSCs showed significantly improved survival compared to those treated with control GFP/NP-hAMCSs. This study demonstrates that synthetic polymeric nanoparticles are a safe and effective approach for stem cell-based cancer-targeting therapies.

BMP-2 induces motility and invasiveness by promoting colon cancer stemness through STAT3 activation

Bone morphogenetic proteins (BMPs) have been involved in metastatic progression and tumorigenesis of many cancer types. However, it remains unclear how BMP-2 contributes to the initiation and development of these cancers. Here, we investigated the role of BMP-2 in colon cancer stem cell (CSC) development from colon cancer cells. We also determined the effects of BMP-2 on CSC development and epithelial-mesenchymal transition (EMT) in human colon cancer cell lines HCT-116 and SW620. We found that BMP-2 enhanced sphere formation of colon cancer cells without serum. Also, BMP-2-induced spheres displayed up-regulation of stemness markers (CD133+ and EpCAM+) and increased drug resistance, hallmarks of CSCs. Importantly, expression of EMT activators p-Smad1/5 and Snail and N-cadherin was increased in the spheres' cells, indicating that BMP-2 signaling might result in CSC self-renewal and EMT. Furthermore, siRNA-mediated knockdown of signal transducer and activator of transcription 3 (STAT3) in HCT-116 cells reversed BMP-2-induced EMT and stem cell formation. Taken together, our results suggest that the BMP-2 induced STAT3-mediated induction of colon cancer cell metastasis requires an EMT and/or changes in CSC markers.

Specific Preferences in Lineage Choice and Phenotypic Plasticity of Glioma Stem Cells Under BMP4 and Noggin Influence

Although BMP4-induced differentiation of glioma stem cells (GSCs) is well recognized, details of the cellular responses triggered by this morphogen are still poorly defined. In this study, we established several GSC-enriched cell lines (GSC-ECLs) from high-grade gliomas. The expansion of these cells as adherent monolayers, and not as floating neurospheres, enabled a thorough study of the phenotypic changes that occurred during their differentiation. Herein, we evaluated GSC-ECLs' behavior toward differentiating conditions by depriving them of growth factors and/or by adding BMP4 at different concentrations. After analyzing cellular morphology, proliferation and lineage marker expression, we determined that GSC-ECLs have distinct preferences in lineage choice, where some of them showed an astrocyte fate commitment and others a neuronal one. We found that this election seems to be dictated by the expression pattern of BMP signaling components present in each GSC-ECL. Additionally, treatment of GSC-ECLs with the BMP antagonist, Noggin, also led to evident phenotypic changes. Interestingly, under certain conditions, some GSC-ECLs adopted an unexpected smooth muscle-like phenotype. As a whole, our findings illustrate the wide differentiation potential of GSCs, highlighting their molecular complexity and paving a way to facilitate personalized differentiating therapies.

A BMP7 Variant Inhibits Tumor Angiogenesis In Vitro and In Vivo through Direct Modulation of Endothelial Cell Biology

Bone morphogenetic proteins (BMPs), members of the TGF-β superfamily, have numerous biological activities including control of growth, differentiation, and vascular development. Using an in vitro co-culture endothelial cord formation assay, we investigated the role of a BMP7 variant (BMP7v) in VEGF, bFGF, and tumor-driven angiogenesis. BMP7v treatment led to disruption of neo-endothelial cord formation and regression of existing VEGF and bFGF cords in vitro. Using a series of tumor cell models capable of driving angiogenesis in vitro, BMP7v treatment completely blocked cord formation. Pre-treatment of endothelial cells with BMP7v significantly reduced their cord forming ability, indicating a direct effect on endothelial cell function. BMP7v activated the canonical SMAD signaling pathway in endothelial cells but targeted gene knockdown using shRNA directed against SMAD4 suggests this pathway is not required to mediate the anti-angiogenic effect. In contrast to SMAD activation, BMP7v selectively decreased ERK and AKT activation, significantly decreased endothelial cell migration and down-regulated expression of critical RTKs involved in VEGF and FGF angiogenic signaling, VEGFR2 and FGFR1 respectively. Importantly, in an in vivo angiogenic plug assay that serves as a measurement of angiogenesis, BMP7v significantly decreased hemoglobin content indicating inhibition of neoangiogenesis. In addition, BMP7v significantly decreased angiogenesis in glioblastoma stem-like cell (GSLC) Matrigel plugs and significantly impaired in vivo growth of a GSLC xenograft with a concomitant reduction in microvessel density. These data support BMP7v as a potent anti-angiogenic molecule that is effective in the context of tumor angiogenesis.

A pathway approach to evaluating the association between the CHIEF pathway and risk of colorectal cancer

Inflammation, hormones and energy-related factors have been associated with colorectal cancer (CRC) and it has been proposed that convergence and interactions of these factors importantly influence CRC risk. We have previously hypothesized that genetic variation in the CHIEF (convergence of hormones, inflammation and energy-related factors) pathway would influence risk of CRC. In this paper, we utilize an Adaptive Rank Truncation Product (ARTP) statistical method to determine the overall pathway significance and then use that method to identify the key elements within the pathway associated with disease risk. Data from two population-based case-control studies of colon (n = 1555 cases and 1956 controls) and rectal (n = 754 cases and 959 controls) cancer were used. We use ARTP to estimate pathway and gene significance and polygenic scores based on ARTP findings to further estimate the risk associated with the pathway. Associations were further assessed based on tumor molecular phenotype. The CHIEF pathway was statistically significant for colon cancer (P(ARTP)= 0.03) with the most significant interferons (P(ARTP) = 0.0253), JAK/STAT/SOCS (P(ARTP) = 0.0111), telomere (P(ARTP) = 0.0399) and transforming growth factor β (P(ARTP) = 0.0043) being the most significant subpathways for colon cancer. For rectal cancer, interleukins (P(ARTP) = 0.0235) and selenoproteins (P ARTP = 0.0047) were statistically significant although the pathway overall was of borderline significance (P(ARTP) = 0.06). Interleukins (P(ARTP) = 0.0456) and mitogen-activated protein kinase (P(ARTP) = 0.0392) subpathways were uniquely significant for CpG island methylator phenotype-positive colon tumors. Increasing number of at-risk alleles was significantly associated with both colon [odds ratio (OR) = 6.21, 95% confidence interval (CI): 4.72, 8.16] and rectal (OR = 7.82, 95% CI: 5.26, 11.62) cancer. We conclude that elements of the CHIEF pathway are important for CRC risk.

Oncolytic Poxviruses

Current standard treatments of cancer can prolong survival of many cancer patients but usually do not effectively cure the disease. Oncolytic virotherapy is an emerging therapeutic for the treatment of cancer that exploits replication-competent viruses to selectively infect and destroy cancerous cells while sparing normal cells and tissues. Clinical and/or preclinical studies on oncolytic viruses have revealed that the candidate viruses being tested in trials are remarkably safe and offer potential for treating many classes of currently incurable cancers. Among these candidates are vaccinia and myxoma viruses, which belong to the family Poxviridae and possess promising oncolytic features. This article describes poxviruses that are being developed for oncolytic virotherapy and summarizes the outcomes of both clinical and preclinical studies. Additionally, studies demonstrating superior efficacy when poxvirus oncolytic virotherapy is combined with conventional therapies are described.

Glioblastoma cancer stem cells: Biomarker and therapeutic advances

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumor in humans. It accounts for fifty-two percent of primary brain malignancies in the United States and twenty percent of all primary intracranial tumors. Despite the current standard therapies of maximal safe surgical resection followed by temozolomide and radiotherapy, the median patient survival is still less than 2 years due to inevitable tumor recurrence. Glioblastoma cancer stem cells (GSCs) are a subgroup of tumor cells that are radiation and chemotherapy resistant and likely contribute to rapid tumor recurrence. In order to gain a better understanding of the many GBM-associated mutations, analysis of the GBM cancer genome is on-going; however, innovative strategies to target GSCs and overcome tumor resistance are needed to improve patient survival. Cancer stem cell biology studies reveal basic understandings of GSC resistance patterns and therapeutic responses. Membrane proteomics using phage and yeast display libraries provides a method to identify novel antibodies and surface antigens to better recognize, isolate, and target GSCs. Altogether, basic GBM and GSC genetics and proteomics studies combined with strategies to discover GSC-targeting agents could lead to novel treatments that significantly improve patient survival and quality of life.

MicroRNA-137 is downregulated in glioblastoma and inhibits the stemness of glioma stem cells by targeting RTVP-1

Glioblastomas (GBM), the most common and aggressive malignant astrocytic tumors, contain a small subpopulation of cancer stem cells (GSCs) that are implicated in therapeutic resistance and tumor recurrence. Here, we study the expression and function of miR-137, a putative suppressor miRNA, in GBM and GSCs. We found that the expression of miR-137 was significantly lower in GBM and GSCs compared to normal brains and neural stem cells (NSCs) and that the miR-137 promoter was hypermethylated in the GBM specimens. The expression of miR-137 was increased in differentiated NSCs and GSCs and overexpression of miR-137 promoted the neural differentiation of both cell types. Moreover, pre-miR-137 significantly decreased the self-renewal of GSCs and the stem cell markers Oct4, Nanog, Sox2 and Shh. We identified RTVP-1 as a novel target of miR-137 in GSCs; transfection of the cells with miR-137 decreased the expression of RTVP-1 and the luciferase activity of RTVP-1 3'-UTR reporter plasmid. Furthermore, overexpression of RTVP-1 plasmid lacking its 3'-UTR abrogated the inhibitory effect of miR-137 on the self-renewal of GSCs. Silencing of RTVP-1 decreased the self-renewal of GSCs and the expression of CXCR4 and overexpression of CXCR4 abrogated the inhibitory effect of RTVP-1 silencing on GSC self-renewal. These results demonstrate that miR-137 is downregulated in GBM probably due to promoter hypermethylation. miR-137 inhibits GSC self-renewal and promotes their differentiation by targeting RTVP-1 which downregulates CXCR4. Thus, miR-137 and RTVP-1 are attractive therapeutic targets for the eradication of GSCs and for the treatment of GBM.

BMP4, a strong better prognosis predictor, has a subtype preference and cell development association in gliomas

Background

The bone morphogenetic family proteins (BMP) are phytogenetically conserved proteins, which are essential for embryonic development. The key regulatory subunit, the bone morphogenetic protein 4 (BMP4), is overexpressed and associated with tumor metastasis in a variety of cancers. However, the prognostic and molecular features of gliomas with BMP4 expression is still unclear.

Methods

We obtained whole genome mRNA expression microarray data of 220 glioma samples of all grades from Chinese Glioma Genome Atlas (CGGA) database (http://www.cgga.org.cn) as discovery set. Of the 123 high-grade gliomas in this set, 33 Grade III tumors and 88 GBMs were analyzed by Kaplan-Meier method. Immunohistochemistry was used for validating the expression of BMP4 in another 77 glioma samples. Three additional datasets were obtained as validation sets. Gene ontology (GO) analysis and gene set variation analysis (GSVA) were used for functional annotation of BMP4.

Results

In the discovery set, BMP4 overexpression was significantly associated with low grade as well as the lower mortality of high-grade gliomas in survival analysis (log-rank, p<0.05 in GBM patients and p<0.01 in anaplastic gliomas, respectively). BMP4 also showed a Proneural subtype, G1 subtype and Isocitrate Dehydrogenase 1 (IDH1) mutation preference and cell development association. The results of validation 4 datasets showed similar findings. The overexpression of BMP4 was also detected in low grade gliomas compared to the high grade ones by immunohistochemistry (p<0.05, chi-square test).

Conclusion

BMP4 expression was independently associated with grade and good prognosis in grade III and grade IV gliomas, suggesting BMP4 as a novel biomarker with potential important therapeutic implications.

Genetic variation in bone morphogenetic proteins and breast cancer risk in hispanic and non-hispanic white women: The breast cancer health disparities study

Bone morphogenetic proteins (BMP) are thought to be important in breast cancer promotion and progression. We evaluated genetic variation in BMP-related genes and breast cancer risk among Hispanic (2,111 cases, 2,597 controls) and non-Hispanic White (NHW) (1,481 cases, 1,586 controls) women who participated in the 4-Corner's Breast Cancer Study, the Mexico Breast Cancer Study and the San Francisco Bay Area Breast Cancer Study. BMP genes and their receptors evaluated include ACVR1, AVCR2A, ACVR2B, ACVRL1, BMP1, BMP2, BMP4, BMP6, BMP7, BMPR1A, BMPR1B, BMPR2, MSTN and GDF10. Additionally, 104 ancestral informative markers were assessed to discriminate between European and native American ancestry. The importance of estrogen on BMP-related associations was suggested through unique associations by menopausal status and estrogen (ER) and progesterone (PR) receptor status of tumors. After adjustment for multiple comparisons ACVR1 (8 SNPs) was modestly associated with ER+PR+ tumors [odds ratios (ORs) between 1.18 and 1.39 padj < 0.05]. ACVR1 (3 SNPs) and BMP4 (3 SNPs) were associated with ER+PR- tumors (ORs 0.59-2.07; padj < 0.05). BMPR2 was associated with ER-PR+ tumors (OR 4.20; 95% CI 1.62, 10.91; padj < 0.05) as was GDF10 (2 SNPs; ORs 3.62 and 3.85; padj < 0.05). After adjustment for multiple comparisons several SNPs remained associated with ER-PR- tumors (padj < 0.05) including ACVR1 BMP4 and GDF10 (ORs between 0.53 and 2.12). Differences in association also were observed by percentage of native ancestry and menopausal status. Results support the hypothesis that genetic variation in BMPs is associated with breast cancer in this admixed population.

Cathepsin B and uPAR regulate self-renewal of glioma-initiating cells through GLI-regulated Sox2 and Bmi1 expression

Cancer-initiating cells comprise a heterogeneous population of undifferentiated cells with the capacity for self-renewal and high proliferative potential. We investigated the role of uPAR and cathepsin B in the maintenance of stem cell nature in glioma-initiating cells (GICs). Simultaneous knockdown of uPAR and cathepsin B significantly reduced the expression of CD133, Nestin, Sox2 and Bmi1 at the protein level and GLI1 and GLI2 at the messenger RNA level. Also, knockdown of uPAR and cathepsin B resulted in a reduction in the number of GICs as well as sphere size. These changes are mediated by Sox2 and Bmi1, downstream of hedgehog signaling. Addition of cyclopamine reduced the expression of Sox2 and Bmi1 along with GLI1 and GLI2 expression, induced differentiation and reduced subsphere formation of GICs thereby indicating that hedgehog signaling acts upstream of Sox2 and Bmi1. Further confirmation was obtained from increased luciferase expression under the control of a GLI-bound Sox2 and Bmi1 luciferase promoter. Simultaneous knockdown of uPAR and cathepsin B also reduced the expression of Nestin Sox2 and Bmi1 in vivo. Thus, our study highlights the importance of uPAR and cathepsin B in the regulation of malignant stem cell self-renewal through hedgehog components, Bmi1 and Sox2.

Regulation of glioblastoma multiforme stem-like cells by inhibitor of DNA binding proteins and oligodendroglial lineage-associated transcription factors

Tumor-initiating stem cells (also referred to as cancer stem cells, CSCs) are a subpopulation of cancer cells that play unique roles in tumor propagation, therapeutic resistance and tumor recurrence. It is increasingly important to understand how molecular signaling regulates the self-renewal and differentiation of CSCs. Basic helix-loop-helix (bHLH) transcription factors are critical for the differentiation of normal stem cells, yet their roles in neoplastic stem cells are not well understood. In glioblastoma neurosphere cultures that contain cancer stem cells (GBM-CSCs), the bHLH family member inhibitors of DNA binding protein 2 and 4 (Id2 and Id4) were found to be upregulated during the differentiation of GBM-CSCs in response to histone deacetylase inhibitors. In this study, we examined the functions of Id2 and Id4 in GBM neurosphere cells and identified Id proteins as efficient differentiation regulators of GBM-CSCs. Overexpression of Id2 and Id4 promoted the lineage-specific differentiation of GBM neurosphere cells as evidenced by the induction of neuronal/astroglial differentiation markers Tuj1 and GFAP and the inhibition of the oligodendroglial marker GalC. Id protein overexpression also reduced both stem cell marker expression and neurosphere formation potential, a biological marker of cancer cell "stemness." We further showed that Id2 and Id4 regulated GBM neurosphere differentiation through downregulating of another bHLH family member, the oligodendroglial lineage-associated transcription factors (Olig) 1 and 2. Our results provide evidence for distinct functions of Id proteins in neoplastic stem cells, which supports Id proteins and their downstream targets as potential candidates for differentiation therapy in CSCs.

Vaccines targeting cancer stem cells: are they within reach?

Increased appreciation of intraclonal heterogeneity of tumors in the past decade has led to the resurgence of the cancer stem cell hypothesis. This hypothesis also has potential implications for immunologic approaches targeting cancer, and it has been suggested that vaccines targeting cancer stem cells may be essential for durable antitumor immunity. Recent studies have provided novel insights into the nature of antigenic targets expressed on putative cancer stem cells and the capacity of both the innate and the adaptive immune system to target these cells, as well as the associated challenges. While the phenotypic properties of cancer stem cells may be plastic, their stemness and capacity for self-renewal may depend on a limited set of genes. Several of these genes overlap with those regulating stemness in embryonal stem cells and are also emerging as potential oncogenes in some cancers. Immunologic approaches targeting stemness-associated pathways in cancer may provide an important strategy for the prevention of diverse cancers, including those occurring in the context of regenerative therapies.

The miR 302-367 cluster drastically affects self-renewal and infiltration properties of glioma-initiating cells through CXCR4 repression and consequent disruption of the SHH-GLI-NANOG network

Glioblastoma multiforme (GBM) is the most common form of primary brain tumor in adults, often characterized by poor survival. Glioma-initiating cells (GiCs) are defined by their extensive self-renewal, differentiation, and tumor initiation properties. GiCs are known to be involved in tumor growth and recurrence, and in resistance to conventional treatments. One strategy to efficiently target GiCs in GBM consists in suppressing their stemness and consequently their tumorigenic properties. In this study, we show that the miR-302-367 cluster is strongly induced during serum-mediated stemness suppression. Stable miR-302-367 cluster expression is sufficient to suppress the stemness signature, self-renewal, and cell infiltration within a host brain tissue, through inhibition of the CXCR4 pathway. Furthermore, inhibition of CXCR4 leads to the disruption of the sonic hedgehog (SHH)-GLI-NANOG network, which is involved in self-renewal and expression of the embryonic stem cell-like signature. In conclusion, we demonstrated that the miR-302-367 cluster is able to efficiently trigger a cascade of inhibitory events leading to the disruption of GiCs stem-like and tumorigenic properties.

Genetic variation in bone morphogenetic protein and colon and rectal cancer

Bone morphogenetic proteins (BMP) are part of the TGF-β-signaling pathway; genetic variation in these genes may be involved in colorectal cancer. In this study, we evaluated the association between genetic variation in BMP1 (11 tagSNPs), BMP2 (5 tagSNPs), BMP4 (3 tagSNPs), BMPR1A (9 tagSNPs), BMPR1B (21 tagSNPs), BMPR2 (11 tagSNPs) and GDF10 (7 tagSNPs) with risk of colon and rectal cancer and tumor molecular phenotype. We used data from population-based case-control studies (colon cancer n = 1,574 cases, 1,970 controls; rectal cancer n = 791 cases, 999 controls). We observed that genetic variation in BMPR1A, BMPR1B, BMPR2, BMP2 and BMP4 was associated with risk of developing colon cancer, with 20 to 30% increased risk for most high-risk genotypes. A summary of high-risk genotypes showed over a twofold increase in colon cancer risk at the upper risk category (OR = 2.49 95% CI = 1.95, 3.18). BMPR2, BMPR1B, BMP2 and GDF10 were associated with rectal cancer. BMPR2 rs2228545 was associated with an almost twofold increased risk of rectal cancer. The risk associated with the highest category of the summary score for rectal cancer was 2.97 (95% CI = 1.87, 4.72). Genes in the BMP-signaling pathway were consistently associated with CIMP+ status in combination with both KRAS-mutated and MSI tumors. BMP genes interacted statistically significantly with other genes in the TGF-β-signaling pathway, including TGFβ1, TGFβR1, Smad 3, Smad 4 and Smad 7. Our data support a role for genetic variation in BMP-related genes in the etiology of colon and rectal cancer. One possible mechanism is via the TGF-β-signaling pathway.

Genetic variation in the transforming growth factor-β signaling pathway and survival after diagnosis with colon and rectal cancer

BACKGROUND

The transforming growth factor-β (TGF-β) signaling pathway is involved in many aspects of tumorigenesis, including angiogenesis and metastasis. The authors evaluated this pathway in association with survival after a diagnosis of colon or rectal cancer.

METHODS

The study included 1553 patients with colon cancer and 754 patients with rectal cancer who had incident first primary disease and were followed for a minimum of 7 years after diagnosis. Genetic variations were evaluated in the genes TGF-β1 (2 single nucleotide polymorphisms [SNPs]), TGF-β receptor 1 (TGF-βR1) (3 SNPs), smooth muscle actin/mothers against decapentaplegic homolog 1 (Smad1) (5 SNPs), Smad2 (4 SNPs), Smad3 (37 SNPs), Smad4 (2 SNPs), Smad7 (11 SNPs), bone morphogenetic protein 1 (BMP1) (11 SNPs), BMP2 (5 SNPs), BMP4 (3 SNPs), bone morphogenetic protein receptor 1A (BMPR1A) (9 SNPs), BMPR1B (21 SNPs), BMPR2 (11 SNPs), growth differentiation factor 10 (GDF10) (7 SNPs), Runt-related transcription factor 1 (RUNX1) (40 SNPs), RUNX2 (19 SNPs), RUNX3 (9 SNPs), eukaryotic translation initiation factor 4E (eiF4E) (3 SNPs), eukaryotic translation initiation factor 4E-binding protein 3 (eiF4EBP2) (2 SNPs), eiF4EBP3 (2 SNPs), and mitogen-activated protein kinase 1 (MAPK1) (6 SNPs).

RESULTS

After adjusting for American Joint Committee on Cancer stage and tumor molecular phenotype, 12 genes and 18 SNPs were associated with survival in patients with colon cancer, and 7 genes and 15 tagSNPs were associated with survival after a diagnosis of rectal cancer. A summary score based on "at-risk" genotypes revealed a hazard rate ratio of 5.10 (95% confidence interval, 2.56-10.15) for the group with the greatest number of "at-risk" genotypes; for rectal cancer, the hazard rate ratio was 6.03 (95% confidence interval, 2.83-12.75).

CONCLUSIONS

The current findings suggest that the presence of several higher risk alleles in the TGF-β signaling pathway increase the likelihood of dying after a diagnosis of colon or rectal cancer.

Brain tumor-initiating cells and cells of origin in glioblastoma

Glioblastoma Multiforme (GBM) is the most malignant and devastating primary brain tumour with a median survival of ∼12–16 months. Although recent large scale sequencing projects have shed considerable light into the complexity of the disease, there remains much to be elucidated in the hopes of generating effective therapeutic strategies. Although these studies investigate the mutations and expression of bulk tumour they have limits with respect to cell of origin and the concept of brain tumour initiating cells (BTIC). Current research has challenged the old paradigm of the stochastic model as recent evidence suggests that a subset of cancer cells within a tumor is responsible for tumor initiation, maintenance, and resistance to therapy. To gain a better understanding of the different compartment of cells that GBM comprise of require careful and elegant experiments. In addition to studying GBM, exploring the role of normal neural stem cells and progenitors cells is essential to partially explain whether these GBM BTIC behave similarly or differently then their non transformed counterparts. Here we discuss the recent literature between the two models, candidate regions of glioma genesis, candidate cells of origin for GBM, and possible therapeutic avenues to explore.

GSK3beta regulates differentiation and growth arrest in glioblastoma

Cancers are driven by a population of cells with the stem cell properties of self-renewal and unlimited growth. As a subpopulation within the tumor mass, these cells are believed to constitute a tumor cell reservoir. Pathways controlling the renewal of normal stem cells are deregulated in cancer. The polycomb group gene Bmi1, which is required for neural stem cell self-renewal and also controls anti-oxidant defense in neurons, is upregulated in several cancers, including medulloblastoma. We have found that Bmi1 is consistently and highly expressed in GBM. Downregulation of Bmi1 by shRNAs induced a differentiation phenotype and reduced expression of the stem cell markers Sox2 and Nestin. Interestingly, expression of glycogen synthase kinase 3 beta (GSK3β), which was found to be consistently expressed in primary GBM, also declined. This suggests a functional link between Bmi1 and GSK3β. Interference with GSK3β activity by siRNA, the specific inhibitor SB216763, or lithium chloride (LiCl) induced tumor cell differentiation. In addition, tumor cell apoptosis was enhanced, the formation of neurospheres was impaired, and clonogenicity reduced in a dose-dependent manner. GBM cell lines consist mainly of CD133-negative (CD133-) cells. Interestingly, ex vivo cells from primary tumor biopsies allowed the identification of a CD133- subpopulation of cells that express stem cell markers and are depleted by inactivation of GSK3β. Drugs that inhibit GSK3, including the psychiatric drug LiCl, may deplete the GBM stem cell reservoir independently of CD133 status.

Cancer stem cells in solid tumors: an overview

It has long been appreciated that significant functional and morphologic heterogeneity can exist within the individual cells that comprise a tumor. Increasing evidence indicates that many solid tumors are organized in a hierarchical manner in which tumor growth is driven by a small subset of cancer stem cells (CSCs) or tumor-initiating cells. Although these cells represent a small percentage of the overall tumor population, they are the only cells capable of initiating and driving tumor growth. Emerging evidence indicates that these cells are also resistant to chemotherapy and radiation therapy, which has led to much speculation and interest surrounding the potential clinical applicability of CSCs.

CD133+ anaplastic thyroid cancer cells initiate tumors in immunodeficient mice and are regulated by thyrotropin

Background

Anaplastic thyroid cancer (ATC) is one of the most lethal human malignancies. Its rapid onset and resistance to conventional therapeutics contribute to a mean survival of six months after diagnosis and make the identification of thyroid-cancer-initiating cells increasingly important.

Methodology/Principal Findings

In prior studies of ATC cell lines, CD133⁺ cells exhibited stem-cell-like features such as high proliferation, self-renewal and colony-forming ability in vitro. Here we show that transplantation of CD133⁺ cells, but not CD133⁻ cells, into immunodeficient NOD/SCID mice is sufficient to induce growth of tumors in vivo. We also describe how the proportion of ATC cells that are CD133⁺ increases dramatically over three months of culture, from 7% to more than 80% of the total. This CD133⁺ cell pool can be further separated by flow cytometry into two distinct populations: CD133^+/high and CD133^+/low. Although both subsets are capable of long-term tumorigenesis, the rapidly proliferating CD133^+/high cells are by far the most efficient. They also express high levels of the stem cell antigen Oct4 and the receptor for thyroid stimulating hormone, TSHR. Treating ATC cells with TSH causes a three-fold increase in the numbers of CD133⁺ cells and elicits a dose-dependent up-regulation of the expression of TSHR and Oct4 in these cells. More importantly, immunohistochemical analysis of tissue specimens from ATC patients indicates that CD133 is highly expressed on tumor cells but not on neighboring normal thyroid cells.

Conclusions/Significance

To our knowledge, this is the first report indicating that CD133⁺ ATC cells are solely responsible for tumor growth in immunodeficient mice. Our data also give a unique insight into the regulation of CD133 by TSH. These highly tumorigenic CD133⁺ cells and the activated TSH signaling pathway may be useful targets for future ATC therapies.

Type-3 metabotropic glutamate receptors negatively modulate bone morphogenetic protein receptor signaling and support the tumourigenic potential of glioma-initiating cells

Targeted-therapies enhancing differentiation of glioma-initiating cells (GICs) are potential innovative approaches to the treatment of malignant gliomas. These cells support tumour growth and recurrence and are resistant to radiotherapy and chemotherapy. We have found that GICs express mGlu3 metabotropic glutamate receptors. Activation of these receptors sustained the undifferentiated state of GICs in culture by negatively modulating the action of bone morphogenetic proteins, which physiologically signal through the phosphorylation of the transcription factors, Smads. The cross-talk between mGlu3 receptors and BMP receptors was mediated by the activation of the mitogen-activated protein kinase pathway. Remarkably, pharmacological blockade of mGlu3 receptors stimulated the differentiation of cultured GICs into astrocytes, an effect that appeared to be long lasting, independent of the growth conditions, and irreversible. In in vivo experiments, a 3-month treatment with the brain-permeant mGlu receptor antagonist, LY341495 limited the growth of infiltrating brain tumours originating from GICs implanted into the brain parenchyma of nude mice. While clusters of tumour cells were consistently found in the brain of control mice, they were virtually absent in a large proportion of mice treated with LY341495. These findings pave the way to a new non-cytotoxic treatment of malignant gliomas based on the use of mGlu3 receptor antagonists.

Prodrug cancer gene therapy

There is no effective treatment for late stage and metastatic cancers of colorectal, prostate, pancreatic, breast, glioblastoma and melanoma cancers. Novel treatment modalities are needed for these late stage patients because cytotoxic chemotherapy offers only palliation, usually accompanied with systemic toxicities and poor quality of life. Gene directed enzyme prodrug therapy (GDEPT), which concentrates the cytotoxic effect in the tumor site may be one alternative. This review provides an explanation of the GDEPT principle, focusing on the development, application and potential of various GDEPTs. Current gene therapy limitations are in efficient expression of the therapeutic gene and in tumor-specific targeting. Therefore, the current status of research related to the enhancement of in situ GDEPT delivery and tumor-specific targeting of vectors is assessed. Finally, GDEPT versions of stem cell based gene therapy as another potential treatment modality for progressed tumors and metastases are discussed. Combinations of traditional, targeted, and stem cell directed gene therapy could significantly advance the treatment of cancer.

Partial biological characterization of cancer stem-like cell line (WJ(2)) of human glioblastoma multiforme

To provide suitable models for human GBM cancer stem cells in vitro and in vivo, and investigate their biological characteristics, a new human GBM cancer stem-like cell line, WJ2, was established in this experiment through serial passages from adherent monolayer culture to nonadherent tumor sphere culture in turns; Its partial biological characteristics were studied through cell proliferation and tumor sphere assay; cell cycle distribution, side population, and CD133 phenotype were analyzed with FCM. The expressions of CD133, Nestin, and GFAP of cancer stem-like cells and xenograft tumor cells were detected with RT-PCR and immunohistochemistry. Biological characterization, side population, CD133 phenotype and CD133 Nestin, BCRP-1, Wnt-1 gene expression revealed the stemness of this cancer stem-like cell line. Tumorigenicity heterotransplanted in nude mice; histopathological characteristics of xenograft tumor, and expressions of CD133, Nestin, and GFAP of xenograft tumor cells indicated that xenograft tumors recapitulated the phenotype and biological characterization of human primary GBM. All findings of this experimental study suggested that WJ(2) cancer stem-like cell line could accurately mimic human GBM cancer stem cell in vitro and in vivo; it would be useful in the cellular and molecular studies as well as in testing novel therapies of CSC-based anti-cancer therapies for human GBM.