Fibroblast growth factor signaling in embryonic and cancer stem cells

Extirpating the cancer stem cell hydra: Differentiation therapy and Hyperthermia therapy for targeting the cancer stem cell hierarchy

Ever since the discovery of cancer stem cells (CSCs), they have progressively attracted more attention as a therapeutic target. Like the mythical hydra, this subpopulation of cells seems to contribute to cancer immortality, spawning more cells each time that some components of the cancer cell hierarchy are destroyed. Traditional modalities focusing on cancer treatment have emphasized apoptosis as a route to eliminate the tumor burden. A major problem is that cancer cells are often in varying degrees of dedifferentiation contributing to what is known as the CSCs hierarchy and cells which are known to be resistant to conventional therapy. Differentiation therapy is an experimental therapeutic modality aimed at the conversion of malignant phenotype to a more benign one. Hyperthermia therapy (HT) is a modality exploiting the changes induced in cells by the application of heat produced to aid in cancer therapy. While differentiation therapy has been successfully employed in the treatment of acute myeloid leukemia, it has not been hugely successful for other cancer types. Mounting evidence suggests that hyperthermia therapy may greatly augment the effects of differentiation therapy while simultaneously overcoming many of the hard-to-treat facets of recurrent tumors. This review summarizes the progress made so far in integrating hyperthermia therapy with existing modules of differentiation therapy. The focus is on studies related to the successful application of both hyperthermia and differentiation therapy when used alone or in conjunction for hard-to-treat cancer cell niche with emphasis on combined approaches to target the CSCs hierarchy.

Exploiting the fibroblast growth factor receptor-1 vulnerability to therapeutically restrict the MYC-EZH2-CDKN1C axis-driven proliferation in Mantle cell lymphoma

Mantle cell lymphoma (MCL) is a lethal hematological malignancy with a median survival of 4 years. Its lethality is mainly attributed to a limited understanding of clinical tumor progression and resistance to current therapeutic regimes. Intrinsic, prolonged drug treatment and tumor-microenvironment (TME) facilitated factors impart pro-tumorigenic and drug-insensitivity properties to MCL cells. Hence, elucidating neoteric pharmacotherapeutic molecular targets involved in MCL progression utilizing a global "unified" analysis for improved disease prevention is an earnest need. Using integrated transcriptomic analyses in MCL patients, we identified a Fibroblast Growth Factor Receptor-1 (FGFR1), and analyses of MCL patient samples showed that high FGFR1 expression was associated with shorter overall survival in MCL patient cohorts. Functional studies using pharmacological intervention and loss of function identify a novel MYC-EZH2-CDKN1C axis-driven proliferation in MCL. Further, pharmacological targeting with erdafitinib, a selective small molecule targeting FGFRs, induced cell-cycle arrest and cell death in-vitro, inhibited tumor progression, and improved overall survival in-vivo. We performed extensive pre-clinical assessments in multiple in-vivo model systems to confirm the therapeutic potential of erdafitinib in MCL and demonstrated FGFR1 as a viable therapeutic target in MCL.

Orai3 Calcium Channel Contributes to Oral/Oropharyngeal Cancer Stemness through the Elevation of ID1 Expression

Emerging evidence indicates that intracellular calcium (Ca2+) levels and their regulatory proteins play essential roles in normal stem cell proliferation and differentiation. Cancer stem-like cells (CSCs) are subpopulations of cancer cells that retain characteristics similar to stem cells and play an essential role in cancer progression. Recent studies have reported that the Orai3 calcium channel plays an oncogenic role in human cancer. However, its role in CSCs remains underexplored. In this study, we explored the effects of Orai3 in the progression and stemness of oral/oropharyngeal squamous cell carcinoma (OSCC). During the course of OSCC progression, the expression of Orai3 exhibited a stepwise augmentation. Notably, Orai3 was highly enriched in CSC populations of OSCC. Ectopic Orai3 expression in non-tumorigenic immortalized oral epithelial cells increased the intracellular Ca2+ levels, acquiring malignant growth and CSC properties. Conversely, silencing of the endogenous Orai3 in OSCC cells suppressed the CSC phenotype, indicating a pivotal role of Orai3 in CSC regulation. Moreover, Orai3 markedly increased the expression of inhibitor of DNA binding 1 (ID1), a stemness transcription factor. Orai3 and ID1 exhibited elevated expression within CSCs compared to their non-CSC counterparts, implying the functional importance of the Orai3/ID1 axis in CSC regulation. Furthermore, suppression of ID1 abrogated the CSC phenotype in the cell with ectopic Orai3 overexpression and OSCC. Our study reveals that Orai3 is a novel functional CSC regulator in OSCC and further suggests that Orai3 plays an oncogenic role in OSCC by promoting cancer stemness via ID1 upregulation.

"DEPHENCE" system-a novel regimen of therapy that is urgently needed in the high-grade serous ovarian cancer-a focus on anti-cancer stem cell and anti-tumor microenvironment targeted therapies

Ovarian cancer, especially high-grade serous type, is the most lethal gynecological malignancy. The lack of screening programs and the scarcity of symptomatology result in the late diagnosis in about 75% of affected women. Despite very demanding and aggressive surgical treatment, multiple-line chemotherapy regimens and both approved and clinically tested targeted therapies, the overall survival of patients is still unsatisfactory and disappointing. Research studies have recently brought some more understanding of the molecular diversity of the ovarian cancer, its unique intraperitoneal biology, the role of cancer stem cells, and the complexity of tumor microenvironment. There is a growing body of evidence that individualization of the treatment adjusted to the molecular and biochemical signature of the tumor as well as to the medical status of the patient should replace or supplement the foregoing therapy. In this review, we have proposed the principles of the novel regimen of the therapy that we called the "DEPHENCE" system, and we have extensively discussed the results of the studies focused on the ovarian cancer stem cells, other components of cancer metastatic niche, and, finally, clinical trials targeting these two environments. Through this, we have tried to present the evolving landscape of treatment options and put flesh on the experimental approach to attack the high-grade serous ovarian cancer multidirectionally, corresponding to the "DEPHENCE" system postulates.

Cancer plasticity: Investigating the causes for this agility

Cancer is not a hard-wired phenomenon but an evolutionary disease. From the onset of carcinogenesis, cancer cells continuously adapt and evolve to satiate their ever-growing proliferation demands. This results in the formation of multiple subtypes of cancer cells with different phenotypes, cellular compositions, and consequently displaying varying degrees of tumorigenic identity and function. This phenomenon is referred to as cancer plasticity, during which the cancer cells exist in a plethora of cellular states having distinct phenotypes. With the advent of modern technologies equipped with enhanced resolution and depth, for example, single-cell RNA-sequencing and advanced computational tools, unbiased cancer profiling at a single-cell resolution are leading the way in understanding cancer cell rewiring both spatially and temporally. In this review, the processes and mechanisms that give rise to cancer plasticity include both intrinsic genetic factors such as epigenetic changes, differential expression due to changes in DNA, RNA, or protein content within the cancer cell, as well as extrinsic environmental factors such as tissue perfusion, extracellular milieu are detailed and their influence on key cancer plasticity hallmarks such as epithelial-mesenchymal transition (EMT) and cancer cell stemness (CSCs) are discussed. Due to therapy evasion and drug resistance, tumor heterogeneity caused by cancer plasticity has major therapeutic ramifications. Hence, it is crucial to comprehend all the cellular and molecular mechanisms that control cellular plasticity. How this process evades therapy, and the therapeutic avenue of targeting cancer plasticity must be diligently investigated.

Schistosoma mansoni Fibroblast Growth Factor Receptor A Orchestrates Multiple Functions in Schistosome Biology and in the Host-Parasite Interplay

Stem cells play significant roles in driving the complex life cycle of Schistosoma mansoni. Fibroblast growth factor (FGF) receptor A (SmFGFRA) is essential for maintaining the integrity of schistosome stem cells. Using immunolocalization, we demonstrated that SmFGFRA was distributed abundantly in germinal/stem cells of different S. mansoni life stages including eggs, miracidia, cercariae, schistosomula and adult worms. Indeed, SmFGFRA was also localized amply in embryonic cells and in the perinuclear region of immature eggs; von Lichtenberg's layer and the neural mass of mature eggs; the ciliated surface and neural mass of miracidia; the tegument cytosol of cercariae, schistosomula and adult worms; and was present in abundance in the testis and vitellaria of adult worms of S. mansoni. The distribution pattern of SmFGFRA illustrates the importance of this molecule in maintaining stem cells, development of the nervous and reproductive system of schistosomes, and in the host-parasite interplay. We showed SmFGFRA can bind human FGFs, activating the mitogen activated protein kinase (MAPK) pathway of adult worms in vitro. Inhibition of FGF signaling by the specific tyrosine kinase inhibitor BIBF 1120 significantly reduced egg hatching ability and affected the behavior of miracidia hatched from the treated eggs, emphasizing the importance of FGF signaling in driving the life cycle of S. mansoni. Our findings provide increased understanding of the complex schistosome life cycle and host-parasite interactions, indicating components of the FGF signaling pathway may represent promising targets for developing new interventions against schistosomiasis.

Pongol Methyl Ether Inhibits Akt and Suppresses Cancer Stem Cell Phenotypes in Lung Cancer Cells

Cancer stem cells (CSCs) are an important therapeutic target. The therapeutic agents targeting CSCs should lead to improved clinical outcomes. Here we have demonstrated the CSC-suppressing activity of pongol methyl ether (PME), a pure compound from Millettia erythrocalyx.

METHODS

CSC-suppressing effects were evaluated by spheroid formation assay and detection of CSC markers. The related CSC cell signals were evaluated by Western blot, immunofluorescence and molecular docking analysis. Proteins affected by PME treatment were subjected to bioinformatic analysis. Protein-protein interaction (PPI) networks were constructed by the Search Tool for Interactions of Chemicals (STITCH). The Kyoto Encyclopedia of Genes and Genomes (KEGG) mapper were used to confirm the underlying pathways.

RESULTS

PME (5-25 µM) significantly suppressed the ability of lung cancer cells to form colonies, grow in an anchorage-independent manner and generate tumour spheroids. PME at 25 µM significantly decreased the CSC markers (CD133 and ALDH1A1) and pluripotent transcription factors (Oct4 and Nanog). Akt, the key upstream signal of CSC control, was significantly decreased by the PME treatment. The molecular docking indicated that PME was bound to Akt-1 with a binding affinity of -9.2 kcal/mol greater than the Akt-1 inhibitor (reference compound; CQW). The STITCH network identified a total of 15 proteins interacted in PPI networks, and Akt-1 was identified as a central protein. The KEGG mapper indicated that the selected CSC markers were mostly involved in the 'signalling pathways regulating pluripotency of stem cells' pathway map and Akt, Oct4 and Nanog were the regulatory proteins in the dominant pathway. In addition, PME (10-25 µM) can suppress spheroid formation and reduce CSC-specific marker expression in patient-derived primary lung cancer cells.

CONCLUSIONS

Our study revealed a novel pharmacological effect and the underlying mechanism of PME that can attenuate CSC phenotypes in lung cancer cells and may be developed for lung cancer therapy.

DYRK1A is required for maintenance of cancer stemness, contributing to tumorigenic potential in oral/oropharyngeal squamous cell carcinoma

DYRK1A, one of the dual-specificity tyrosine phosphorylation-regulated kinases (DYRKs), plays an important role in various biological processes by regulating downstream targets via kinase-dependent and independent mechanisms. Here, we report a novel role of DYRK1A in maintaining tumor growth and stemness of oral/oropharyngeal squamous cell carcinoma (OSCC) cells. Deletion of DYRK1A from OSCC cells abrogated their in vivo tumorigenicity and self-renewal capacity, the key features of cancer stem-like cells (CSCs; also referred to as tumor-initiating cells). The DYRK1A deletion also induced the suppression of CSC populations and properties, such as migration ability and chemoresistance. Conversely, ectopic expression of DYRK1A in OSCC cells augmented their CSC phenotype. Among five DYRK members (DYRK1A, 1B, 2, 3, and 4), DYRK1A is the most dominantly expressed kinase, and its expression is upregulated in OSCC compared to normal oral epithelial cells. More importantly, DYRK1A was highly enriched in various CSC-enriched OSCC populations compared to their corresponding non-CSC populations, indicating its pivotal role in cancer progression and stemness. Further, our study revealed that fibroblast growth factor 2 (FGF2) is a key regulator in the DYRK1A-mediated CSC regulation. Functional studies demonstrated that the loss of DYRK1A inhibits CSC phenotype via reduction of FGF2. Overexpression of DYRK1A promotes CSC phenotype via upregulation of FGF2. Our study delineates a novel mechanism of cancer stemness regulation by DYRK1A-FGF2 axis in OSCC. Thus, inhibition of DYRK1A would lead to a potential novel therapeutic option for targeting CSCs in OSCC.

Therapeutic Strategies for Targeting Ovarian Cancer Stem Cells

Ovarian cancer is a fatal gynecological malignancy. Although first-line chemotherapy and surgical operation are effective treatments for ovarian cancer, its clinical management remains a challenge owing to intrinsic or acquired drug resistance and relapse at local or distal lesions. Cancer stem cells (CSCs) are a small subpopulation of cells inside tumor tissues, and they can self-renew and differentiate. CSCs are responsible for the cancer malignancy involved in relapses as well as resistance to chemotherapy and radiation. These malignant properties of CSCs are regulated by cell surface receptors and intracellular pluripotency-associated factors triggered by internal or external stimuli from the tumor microenvironment. The malignancy of CSCs can be attenuated by individual or combined restraining of cell surface receptors and intracellular pluripotency-associated factors. Therefore, targeted therapy against CSCs is a feasible therapeutic tool against ovarian cancer. In this paper, we review the prominent roles of cell surface receptors and intracellular pluripotency-associated factors in mediating the stemness and malignancy of ovarian CSCs.

MicroRNA-202 inhibits cell migration and invasion through targeting FGF2 and inactivating Wnt/β-catenin signaling in endometrial carcinoma

Recently, many mircroRNAs (miRNAs) involved in the development and progression of cancer have been reported to regulate cell growth and metastasis, including microRNA-202 (miR-202). The purpose of the present study was to elucidate the effect of miR-202 on endometrial carcinoma (EC) cell migration and invasion. First, qRT-PCR showed that miR-202 was down-regulated in EC tissues, which was associated with poor prognosis in EC patients. Functionally, transwell assay indicated that miR-202 inhibited cell migration and invasion in EC cells. In addition, miR-202 also blocked epithelial-mesenchymal transition (EMT) through suppressing N-cadherin and Vimentin expressions and promoting E-cadherin expression. Moreover, the dual-luciferase reporter assay showed that fibroblast growth factor 2 (FGF2) is a direct target gene for miR-202 in EC cells. Furthermore, up-regulation of FGF2 attenuated the inhibitory effect of miR-202 on cell migration and invasion in EC. Besides that, miR-202 inactivated the Wnt/β-catenin signaling by suppressing β-catenin expression in EC. In conclusion, miR-202 inhibited cell migration and invasion by targeting FGF2 and inactivating the Wnt/β-catenin signaling in EC.

Mechanisms of cancer stem cell therapy

Cancer stem cells (CSCs) are responsible for carcinogenesis and tumorigenesis and are involved in drug and radiation resistance, metastasis, tumor relapse and initiation. Remarkably, they have other abilities such as inheritance of self-renewal and de-differentiation. Hence, targeting CSCs is considered a potential anti-cancer therapeutic strategy. Recent advances in the identification of biomarkers to recognize CSCs and the development of new techniques to evaluate tumorigenic and carcinogenic roles of CSCs are instrumental to this approach. Elucidation of signaling pathways that regulate CSCs colony progression and drug resistance are critical in establishing effective targeted therapies. CSCs play a central key role in immunomodulation, immune evasion and effector immunity, which alters immune system balancing. These include mTOR, SHH, NOTCH and Wnt/β-catering in cancer progression. In this review article, we discuss the importance of these CSCs pathways in cancer therapy.

DECIPHER pooled shRNA library screen identifies PP2A and FGFR signaling as potential therapeutic targets for diffuse intrinsic pontine gliomas

BACKGROUND

Diffuse intrinsic pontine gliomas (DIPGs) are highly aggressive pediatric brain tumors that are characterized by a recurrent mutation (K27M) within the histone H3 encoding genes H3F3A and HIST1H3A/B/C. These mutations have been shown to induce a global reduction in the repressive histone modification H3K27me3, which together with widespread changes in DNA methylation patterns results in an extensive transcriptional reprogramming hampering the identification of single therapeutic targets based on a molecular rationale.

METHODS

We applied a large-scale gene knockdown approach using a pooled short hairpin (sh)RNA library in combination with next-generation sequencing in order to identify DIPG-specific vulnerabilities. The therapeutic potential of specific inhibitors of candidate targets was validated in a secondary drug screen.

RESULTS

We identified fibroblast growth factor receptor (FGFR) signaling and the serine/threonine protein phosphatase 2A (PP2A) as top depleted hits in patient-derived DIPG cell cultures and validated their lethal potential by FGF ligand depletion and genetic knockdown of the PP2A structural subunit PPP2R1A. Further, pharmacological inhibition of FGFR and PP2A signaling through ponatinib and LB-100 treatment, respectively, exhibited strong tumor-specific anti-proliferative and apoptotic activity in cultured DIPG cells.

CONCLUSIONS

Our findings suggest FGFR and PP2A signaling as potential new therapeutic targets for the treatment of DIPGs.

Emerging Methods for Enhancing Pluripotent Stem Cell Expansion

Pluripotent stem cells (PSCs) have great potential to revolutionize the fields of tissue engineering and regenerative medicine as well as stem cell therapeutics. However, the end goal of using PSCs for therapeutic use remains distant due to limitations in current PSC production. Conventional methods for PSC expansion have limited potential to be scaled up to produce the number of cells required for the end-goal of therapeutic use due to xenogenic components, high cost or low efficiency. In this mini review, we explore novel methods and emerging technologies of improving PSC expansion: the use of the two-dimensional mechanobiological strategies of topography and stiffness and the use of three-dimensional (3D) expansion methods including encapsulation, microcarrier-based culture, and suspension culture. Additionally, we discuss the limitations of conventional PSC expansion methods as well as the challenges in implementing non-conventional methods.

Fibroblast growth factor-2 stimulates proliferation of human adipose-derived stem cells via Src activation

Background

Human adipose-derived stem cells (hASCs) are a subset of mesenchymal stem cells (MSCs); it has been regarded as one of the most promising stem cells. We previously found that fibroblast growth factor-2 (FGF-2) enhanced the proliferation and differentiation of hASC. However, the mechanisms involved in the growth of hASCs by FGF-2 have not been investigated.

Methods

Human adipose-derived stem cells (hASCs) were cultured with FGF-2, and cell growth was assessed. Effects of FGF Receptor (FGFR) inhibitor (NVP-BGJ398), ERK1/2 inhibitor (PD98059), PI3K/Akt inhibitor (LY294002), JNK inhibitor (SP600125), and p38 MAPK inhibitor (SB203580) and Src inhibitor (PP1) on the proliferation were investigated. At the same time, we assessed the effect of FGFR inhibitor on several signaling enzymes such as ERK1/2, JNK, p38, and Akt, in protein level. The involvement of Src activation by FGF-2 was also examined.

Results

FGF-2 markedly promoted proliferation of hASCs at concentrations lower than 10 ng/ml and stimulated cell progression to the S and G2/M phases. Proliferation was blocked by the FGFR inhibitor (NVP-BGJ398) and various signaling pathway inhibitors, such as Erk1/2 inhibitor (PD98059), PI3K/Akt inhibitor (LY294002), JNK inhibitor (SP600125), and p38MAPK inhibitor (SB203580). The FGFR inhibitor reduced the activation of protein kinases, such as AKT, Erk1/2, JNK, and p38, in several signaling pathways. The downstream kinase of FGFR, Src, was activated by FGF-2, and its activation was canceled by the FGFR inhibitor. MEK1/2, a downstream kinase of Src, was parallelly regulated by FGF-2. The Src inhibitor (PP1) markedly blocked the proliferation of hASCs via inhibition of Src and MEK1/2.

Conclusion

Src activation is indispensable for FGF-2-mediated proliferation of ASCs, as well as the subsequent activation of multi-signaling pathways.

Peglated-H1/pHGFK1 nanoparticles enhance anti-tumor effects of sorafenib by inhibition of drug-induced autophagy and stemness in renal cell carcinoma

Background

Tumor targeting small molecular inhibitors are the most popular treatments for many malignant diseases, including cancer. However, the lower clinical response and drug resistance still limit their clinical efficacies. HGFK1, the first kringle domain of hepatocyte growth factor, has been defined as a potent anti-angiogenic factor. Here, we aimed to develop and identify novel nanoparticles—PH1/pHGFK1 as potential therapeutic agents for the treatment of renal cell carcinoma (RCC).

Methods

We produced a novel cationic polymer—PH1 and investigated the anti-tumor activity of PH1/pHGFK1 nanoparticle alone and its combination therapy with sorafenib in RCC cell line xenografted mice model. Then, we figured out its molecular mechanisms in human RCC cell lines in vitro.

Results

We firstly demonstrated that intravenous injection of PH1/pHGFK1 nanoparticles significantly inhibited tumor growth and prolonged the survival time of tumor-bearing mice, as well as synergistically enhanced anti-tumor activities of sorafenib. Furthermore, we elucidated that recombinant HGFK1 improved sorafenib-induced cell apoptosis and arrested cell cycle. In addition, HGFK1 could also decrease sorafenib-induced autophagy and stemness via blockading NF-κB signaling pathway in RCC both in vitro and in vivo.

Conclusions

HGFK1 could inhibit tumor growth, synergistically enhance anti-tumor activities of sorafenib and reverse its drug resistance evolution in RCC. Our results provide rational basis for clinical application of sorafenib and HGFK1 combination therapy in RCC patients.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1348-z) contains supplementary material, which is available to authorized users.

Basic fibroblast growth factor signalling regulates cancer stem cells in lung cancer A549 cells

OBJECTIVES

The basic fibroblast growth factor (bFGF)/fibroblast growth factor receptor (FGFR) signal transductional pathway plays an important role not only in tumour, but also in tumour stem cells. Thus, this study was designed to investigate the effects of bFGF signalling on cancer stem cells of lung cancer.

METHODS

We blocked bFGF/FGFR signalling in cisplatin (DDP) selected A549 by knocking down bFGF via RNA interference, and subsequently, the stem cell marker of OCT-4 was determined, and cell proliferation, clone formation, invasiveness, apoptosis and drug resistance abilities of DDP selected A549 cells were investigated.

KEY FINDINGS

The expressions of bFGF and OCT-4 in DDP selected A549 were higher than that of A549 cells. The findings suggested blocking of bFGF/FGFR signalling resulted in downregulation of bFGF, reduction in cell proliferation, clone formation, invasion and drug resistance abilities, and increase in cell apoptosis. Furthermore, our results also revealed OCT-4 was reduced after bFGF signalling blocking.

CONCLUSIONS

In conclusion, our study suggested that bFGF/FGFR signalling plays an important role in maintaining lung cancer stem cell characteristics and regulating expression of cancer stem cell marker of OCT-4.

FGF family members differentially regulate maturation and proliferation of stem cell-derived astrocytes

The glutamate transporter 1 (GLT1) is upregulated during astrocyte development and maturation in vivo and is vital for astrocyte function. Yet it is expressed at low levels by most cultured astrocytes. We previously showed that maturation of human and mouse stem cell-derived astrocytes – including functional glutamate uptake – could be enhanced by fibroblast growth factor (FGF)1 or FGF2. Here, we examined the specificity and mechanism of action of FGF2 and other FGF family members, as well as neurotrophic and differentiation factors, on mouse embryonic stem cell-derived astrocytes. We found that some FGFs – including FGF2, strongly increased GLT1 expression and enhanced astrocyte proliferation, while others (FGF16 and FGF18) mainly affected maturation. Interestingly, BMP4 increased astrocytic GFAP expression, and BMP4-treated astrocytes failed to promote the survival of motor neurons in vitro. Whole transcriptome analysis showed that FGF2 treatment regulated multiple genes linked to cell division, and that the mRNA encoding GLT1 was one of the most strongly upregulated of all astrocyte canonical markers. Since GLT1 is expressed at reduced levels in many neurodegenerative diseases, activation of this pathway is of potential therapeutic interest. Furthermore, treatment with FGFs provides a robust means for expansion of functionally mature stem cell-derived astrocytes for preclinical investigation.

Combination of heterologous fibrin sealant and bioengineered human embryonic stem cells to improve regeneration following autogenous sciatic nerve grafting repair

Background

Peripheral nerve injury is a worldwide clinical problem, and the preferred surgical method for treating it is the end-to-end neurorrhaphy. When it is not possible due to a large nerve gap, autologous nerve grafting is used. However, these surgical techniques result in nerve regeneration at highly variable degrees. It is thus very important to seek complementary techniques to improve motor and sensory recovery. One promising approach could be cell therapy. Transplantation therapy with human embryonic stem cells (hESCs) is appealing because these cells are pluripotent and can differentiate into specialized cell types and have self-renewal ability. Therefore, the main objective of this study was to find conditions under which functional recovery is improved after sciatic nerve neurorrhaphy. We assumed that hESC, either alone or in combination with heterologous fibrin sealant scaffold, could be used to support regeneration in a mouse model of sciatic nerve injury and repair via autografting with end-to-end neurorrhaphy.

Methods

Five millimeters of the sciatic nerve of C57BL/6 J mice were transected off and rotated 180 degrees to simulate an injury, and then stumps were sutured. Next, we applied heterologous fibrin sealant and/or human embryonic stem cells genetically altered to overexpress fibroblast growth factor 2 (FGF2) at the site of the injury. The study was designed to include six experimental groups comprising neurorrhaphy (N), neurorrhaphy + heterologous fibrin sealant (N + F), neurorrhaphy + heterologous fibrin sealant + doxycycline (N + F + D), neurorrhaphy + heterologous fibrin sealant + wild-type hESC (N + F + W), neurorrhaphy + heterologous fibrin sealant + hESC off (N + F + T), and neurorrhaphy + heterologous fibrin sealant + hESC on via doxycycline (N + F + D + T). We evaluated the recovery rate using Catwalk and von Frey functional recovery tests, as well as immunohistochemistry analysis.

Results

The experiments indicated that sensory function improved when transgenic hESCs were used. The regeneration of sensory fibers indeed led to increased reflexes, upon stimulation of the paw ipsilateral to the lesion, as seen by von-Frey evaluation, which was supported by immunohistochemistry.

Conclusions

Overall, the present data demonstrated that transgenic embryonic stem cells, engineered to overexpress FGF-2 in an inducible fashion, could be employed to support regeneration aiming at the recovery of both motor and sensory functions.

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.

Elucidating the gene regulatory networks modulating cancer stem cells and non-stem cancer cells in high grade serous ovarian cancer

The origin and pathogenesis of epithelial ovarian cancer have perplexed investigators for decades. The most prevalent type of it is the high-grade serous ovarian carcinoma (HGSOv) which is a highly aggressive disease with high relapse rates and insurgence of chemo-resistance at later stages of treatment. These are driven by a rare population of stem cell like cancer cells called cancer stem cells (CSCs). We have taken up a systems approach to find out the common gene interaction paths between non-CSC tumor cells (CCs) and CSCs in HGSOv. Detailed investigation reveals a set of 17 Transcription Factors (named as pivot-TFs) which can govern changes in the mode of gene regulation along these paths. Overall, this work highlights a divergent road map of functional information relayed by these common key players in the two cell states, which might aid towards designing novel therapeutic measures to target the CSCs for ovarian cancer therapy.

Unconventional Protein Secretion in Animal Cells

All eukaryotic cells secrete a range of proteins in a constitutive or regulated manner through the conventional or canonical exocytic/secretory pathway characterized by vesicular traffic from the endoplasmic reticulum, through the Golgi apparatus, and towards the plasma membrane. However, a number of proteins are secreted in an unconventional manner, which are insensitive to inhibitors of conventional exocytosis and use a route that bypasses the Golgi apparatus. These include cytosolic proteins such as fibroblast growth factor 2 (FGF2) and interleukin-1β (IL-1β), and membrane proteins that are known to also traverse to the plasma membrane by a conventional process of exocytosis, such as α integrin and the cystic fibrosis transmembrane conductor (CFTR). Mechanisms underlying unconventional protein secretion (UPS) are actively being analyzed and deciphered, and these range from an unusual form of plasma membrane translocation to vesicular processes involving the generation of exosomes and other extracellular microvesicles. In this chapter, we provide an overview on what is currently known about UPS in animal cells.

EGFR-mediated interleukin enhancer-binding factor 3 contributes to formation and survival of cancer stem-like tumorspheres as a therapeutic target against EGFR-positive non-small cell lung cancer

OBJECTIVES

YM155, an inhibitor of interleukin enhancer-binding factor 3 (ILF3), significantly suppresses cancer stemness property, implying that ILF3 contributes to cell survival of cancer stem cells. However, the molecular function of ILF3 inhibiting cancer stemness remains unclear. This study aimed to uncover the potential function of ILF3 involving in cell survival of epidermal growth factor receptor (EGFR)-positive lung stem-like cancer, and to investigate the potential role to improve the efficacy of anti-EGFR therapeutics.

MATERIALS AND METHODS

The association of EGFR and ILF3 in expression and regulations was first investigated in this study. Lung cancer A549 cells with deprivation of ILF3 were created by the gene-knockdown method and then RNAseq was applied to identify the putative genes regulated by ILF3. Meanwhile, HCC827- and A549-derived cancer stem-like cells were used to investigate the role of ILF3 in the formation of cancer stem-like tumorspheres.

RESULTS

We found that EGFR induced ILF3 expression, and YM155 reduced EGFR expression. The knockdown of ILF3 reduced not only EGFR expression in mRNA and protein levels, but also cell proliferation in vitro and in vivo, demonstrating that ILF3 may play an important role in contributing to cancer cell survival. Moreover, the knockdown and inhibition of ILF3 by shRNA and YM155, respectively, reduced the formation and survival of HCC827- and A549-derived tumorspheres through inhibiting ErbB3 (HER3) expression, and synergized the therapeutic efficacy of afatinib, a tyrosine kinase inhibitor, against EGFR-positive A549 lung cells.

CONCLUSION

This study demonstrated that ILF3 plays an oncogenic like role in maintaining the EGFR-mediated cellular pathway, and can be a therapeutic target to improve the therapeutic efficacy of afatinib. Our results suggested that YM155, an ILF3 inhibitor, has the potential for utilization in cancer therapy against EGFR-positive lung cancers.

Circulating tumour cells from patients with colorectal cancer have cancer stem cell hallmarks in ex vivo culture

OBJECTIVE

Although counting of circulating tumour cells (CTC) has attracted a broad interest as potential markers of tumour progression and treatment response, the lack of functional characterisation of these cells had become a bottleneck in taking these observations to the clinic. Our objective was to culture these cells in order to understand them and exploit their therapeutic potential to the full.

DESIGN

Here, hypothesising that some CTC potentially have cancer stem cell (CSC) phenotype, we generated several CTC lines from the blood of patients with advanced metastatic colorectal cancer (CRC) based on their self-renewal abilities. Multiple standard tests were then employed to characterise these cells.

RESULTS

Our CTC lines self-renew, express CSC markers and have multilineage differentiation ability, both in vitro and in vivo. Patient-derived CTC lines are tumorigenic in subcutaneous xenografts and are also able to colonise the liver after intrasplenic injection. RNA sequencing analyses strikingly demonstrate that drug metabolising pathways represent the most upregulated feature among CTC lines in comparison with primary CRC cells grown under similar conditions. This result is corroborated by the high resistance of the CTC lines to conventional cytotoxic compounds.

CONCLUSIONS

Taken together, our results directly demonstrate the existence of patient-derived colorectal CTCs that bear all the functional attributes of CSCs. The CTC culture model described here is simple and takes <1 month from blood collection to drug testing, therefore, routine clinical application could facilitate access to personalised medicine.

CLINICAL TRIAL REGISTRATION

ClinicalTrial.gov NCT01577511.

Transgenic human embryonic stem cells overexpressing FGF2 stimulate neuroprotection following spinal cord ventral root avulsion

Ventral root avulsion (VRA) triggers a strong glial reaction which contributes to neuronal loss, as well as to synaptic detachment. To overcome the degenerative effects of VRA, treatments with neurotrophic factors and stem cells have been proposed. Thus, we investigated neuroprotection elicited by human embryonic stem cells (hESC), modified to overexpress a human fibroblast growth factor 2 (FGF-2), on motoneurons subjected to VRA. Lewis rats were submitted to VRA (L4-L6) and hESC/FGF-2 were applied to the injury site using a fibrin scaffold. The spinal cords were processed to evaluate neuronal survival, synaptic stability, and glial reactivity two weeks post lesion. Then, qRT-PCR was used to assess gene expression of β2-microglobulin (β2m), TNFα, IL1β, IL6 and IL10 in the spinal cord in vivo and FGF2 mRNA levels in hESC in vitro. The results indicate that hESC overexpressing FGF2 significantly rescued avulsed motoneurons, preserving synaptic covering and reducing astroglial reactivity. The cells were also shown to express BDNF and GDNF at the site of injury. Additionally, engraftment of hESC led to a significant reduction in mRNA levels of TNFα at the spinal cord ventral horn, indicating their immunomodulatory properties. Overall, the present data suggest that hESC overexpressing FGF2 are neuroprotective and can shift gene expression towards an anti-inflammatory environment.

A molecular dynamics-based algorithm for evaluating the glycosaminoglycan mimicking potential of synthetic, homogenous, sulfated small molecules

Glycosaminoglycans (GAGs) are key natural biopolymers that exhibit a range of biological functions including growth and differentiation. Despite this multiplicity of function, natural GAG sequences have not yielded drugs because of problems of heterogeneity and synthesis. Recently, several homogenous non-saccharide glycosaminoglycan mimetics (NSGMs) have been reported as agents displaying major therapeutic promise. Yet, it remains unclear whether sulfated NSGMs structurally mimic sulfated GAGs. To address this, we developed a three-step molecular dynamics (MD)-based algorithm to compare sulfated NSGMs with GAGs. In the first step of this algorithm, parameters related to the range of conformations sampled by the two highly sulfated molecules as free entities in water were compared. The second step compared identity of binding site geometries and the final step evaluated comparable dynamics and interactions in the protein-bound state. Using a test case of interactions with fibroblast growth factor-related proteins, we show that this three-step algorithm effectively predicts the GAG structure mimicking property of NSGMs. Specifically, we show that two unique dimeric NSGMs mimic hexameric GAG sequences in the protein-bound state. In contrast, closely related monomeric and trimeric NSGMs do not mimic GAG in either the free or bound states. These results correspond well with the functional properties of NSGMs. The results show for the first time that appropriately designed sulfated NSGMs can be good structural mimetics of GAGs and the incorporation of a MD-based strategy at the NSGM library screening stage can identify promising mimetics of targeted GAG sequences.

Re-calculating! Navigating through the osteosarcoma treatment roadblock

The survival rates for patients with osteosarcoma have remained almost static for the past three decades. Current standard of care therapy includes chemotherapies such as doxorubicin, cisplatin, and methotrexate along with complete surgical resection and surgery with or without ifosfamide and etoposide for relapse, though outcomes are hoped to be improved through clinical trials. Additionally, increased understanding of the genetics, signaling pathways and microenvironmental factors driving the disease have led to the identification of promising agents and potential paths towards translation of an exciting array of novel targeted therapies. Here, we review the mechanism of action of these emerging therapies and how, with clinical translation, they can potentially improve the survival rates for osteosarcoma patients in the near future.

FGFR1 is an adverse outcome indicator for luminal A breast cancers

Fibroblast growth factor receptor 1 (FGFR1) has been suggested to be the candidate gene for 8p11-12 amplification in breast cancer and its therapeutic/ prognostic value is explored. Most previous studies focused on FGFR1 gene amplification, which may not necessarily lead to protein expression. Therefore, analysis of protein level may have more clinical relevance. We evaluated FGFR1 expression in a large cohort of breast cancer by immunohistochemistry, correlated with the tumor clinic-pathologic features, biomarkers expression, and patient's survival. FGFR1 expression was associated mainly with luminal cancers, particularly luminal B subtype (23.5%; p < 0.001), and it also showed adverse prognostic impact on luminal A cancers. FGFR1 expression was associated with higher pN (p = 0.023), pT (p = 0.003) stages, lymphovascular invasion (p = 0.010), p-cadherin (p = 0.028), synaptophysin (p = 0.009) and SOX2 expression (p = 0.034) in luminal A cancers. FGFR1 expressing luminal A cancers showed a similar outcome as luminal B cancers. Multivariate Cox regression analysis demonstrated FGFR1 positive luminal A cancers to be an independently poor prognosticator for disease free survival in luminal cancers (hazard ratio = 3.341, p = 0.008). Thus FGFR1 could be useful in identifying the aggressive cases amongst heterogeneous luminal A cancers. Given the relevance of FGFR pathway in treatment resistance in luminal cancers, FGFR1 could be an important tumor biomarker and adverse prognostic factor potentially exploitable in the clinical management of luminal cancers.

Autophagy regulates cytoplasmic remodeling during cell reprogramming in a zebrafish model of muscle regeneration

Cell identity involves both selective gene activity and specialization of cytoplasmic architecture and protein machinery. Similarly, reprogramming differentiated cells requires both genetic program alterations and remodeling of the cellular architecture. While changes in genetic and epigenetic programs have been well documented in dedifferentiating cells, the pathways responsible for remodeling the cellular architecture and eliminating specialized protein complexes are not as well understood. Here, we utilize a zebrafish model of adult muscle regeneration to study cytoplasmic remodeling during cell dedifferentiation. We describe activation of autophagy early in the regenerative response to muscle injury, while blocking autophagy using chloroquine or Atg5 and Becn1 knockdown reduced the rate of regeneration with accumulation of sarcomeric and nuclear debris. We further identify Casp3/caspase 3 as a candidate mediator of cellular reprogramming and Fgf signaling as an important activator of autophagy in dedifferentiating myocytes. We conclude that autophagy plays a critical role in cell reprogramming by regulating cytoplasmic remodeling, facilitating the transition to a less differentiated cell identity.

Cell-based tissue engineering strategies used in the clinical repair of articular cartilage

One of the most important issues facing cartilage tissue engineering is the inability to move technologies into the clinic. Despite the multitude of current research in the field, it is known that 90% of new drugs that advance past animal studies fail clinical trials. The objective of this review is to provide readers with an understanding of the scientific details of tissue engineered cartilage products that have demonstrated a certain level of efficacy in humans, so that newer technologies may be developed upon this foundation. Compared to existing treatments, such as microfracture or autologous chondrocyte implantation, a tissue engineered product can potentially provide more consistent clinical results in forming hyaline repair tissue and in filling the entirety of the defect. The various tissue engineering strategies (e.g., cell expansion, scaffold material, media formulations, biomimetic stimuli, etc.) used in forming these products, as collected from published literature, company websites, and relevant patents, are critically discussed. The authors note that many details about these products remain proprietary, not all information is made public, and that advancements to the products are continuously made. Nevertheless, by understanding the design and production processes of these emerging technologies, one can gain tremendous insight into how to best use them and also how to design the next generation of tissue engineered cartilage products.

Cell-based tissue engineering strategies used in the clinical repair of articular cartilage

One of the most important issues facing cartilage tissue engineering is the inability to move technologies into the clinic. Despite the multitude of current research in the field, it is known that 90% of new drugs that advance past animal studies fail clinical trials. The objective of this review is to provide readers with an understanding of the scientific details of tissue engineered cartilage products that have demonstrated a certain level of efficacy in humans, so that newer technologies may be developed upon this foundation. Compared to existing treatments, such as microfracture or autologous chondrocyte implantation, a tissue engineered product can potentially provide more consistent clinical results in forming hyaline repair tissue and in filling the entirety of the defect. The various tissue engineering strategies (e.g., cell expansion, scaffold material, media formulations, biomimetic stimuli, etc.) used in forming these products, as collected from published literature, company websites, and relevant patents, are critically discussed. The authors note that many details about these products remain proprietary, not all information is made public, and that advancements to the products are continuously made. Nevertheless, by understanding the design and production processes of these emerging technologies, one can gain tremendous insight into how to best use them and also how to design the next generation of tissue engineered cartilage products.

Suppression of Spry4 enhances cancer stem cell properties of human MDA-MB-231 breast carcinoma cells

BACKGROUND

Cancer stem cells contribute to tumor initiation, heterogeneity, and recurrence, and are critical targets in cancer therapy. Sprouty4 (Spry4) is a potent inhibitor of signal transduction pathways elicited by receptor tyrosine kinases, and has roles in regulating cell proliferation, migration and differentiation. Spry4 has been implicated as a tumor suppressor and in modulating embryonic stem cells.

OBJECTIVES

The purpose of this research was to test the novel idea that Spry4 regulates cancer stem cell properties in breast cancer.

METHODS

Loss-of function of Spry4 in human MDA-MB-231 cell was used to test our hypothesis. Spry4 knockdown or control cell lines were generated using lentiviral delivery of human Spry4 or non-targeting control shRNAs, and then selected with 2 μg/ml puromycin. Cell growth and migratory abilities were determined using growth curve and cell cycle flow cytometry analyses and scratch assays, respectively. Xenograft tumor model was used to determine the tumorigenic activity and metastasis in vivo. Cancer stem cell related markers were evaluated using immunoblotting assays and fluorescence-activated cell sorting. Cancer stem cell phenotype was evaluated using in vitro mammosphere formation and drug sensitivity tests, and in vivo limiting dilution tumor formation assay.

RESULTS

Two out of three tested human Spry4 shRNAs significantly suppressed the expression of endogenous Spry4 in MDA-MB-231 cells. Suppressing Spry4 expression increased MDA-MB-231 cell proliferation and migration. Suppressing Spry4 increased β3-integrin expression, and CD133(+)CD44(+) subpopulation. Suppressing Spry4 increased mammosphere formation, while decreasing the sensitivity of MDA-MB-231 cells to Paclitaxel treatment. Finally, suppressing Spry4 increased the potency of MDA-MB-231 cell tumor initiation, a feature attributed to cancer stem cells.

CONCLUSIONS

Our findings provide novel evidence that endogenous Spry4 may have tumor suppressive activity in breast cancer by suppressing cancer stem cell properties in addition to negative effects on tumor cell proliferation and migration.

Synthesis of the copper chelator TGTA and evaluation of its ability to protect biomolecules from copper induced degradation during copper catalyzed azide-alkyne bioconjugation reactions

One of the most successful bioconjugation strategies to date is the copper(I)-catalyzed cycloaddition reaction (CuAAC), however, the typically applied reaction conditions have been found to degrade sensitive biomolecules. Herein, we present a water soluble copper chelator which can be utilized to protect biomolecules from copper induced degradation.

Fibroblast and Epidermal Growth Factors Utilize Different Signaling Pathways to Induce Anchorage-independent Cell Transformation in JB6 Cl41 Mouse Skin Epidermal Cells

Background:

Extracellular stimulation of cells with growth factors such as epidermal growth factor (EGF) induces cell proliferation and cell transformation. Although fibroblast growth factor (FGF) is a well-known family member of growth factors and acts as a ligand of FGF receptor (FGFR), a receptor tyrosine kinase, in cytoplasmic membrane, the tumor promoter potential of FGF has not been clearly understood.

Methods:

The role of FGF as a tumor promoter was determined measuring its effects of cell proliferation and transformation by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium and anchorage-independent cell transformation assays, respectively. The antibody specificity of phospho-RSK2 Tyr529 was determined by Western blotting using a purified FGFR kinase domain in vitro and the membrane fraction of JB6 Cl41 cells ex vivo. The signaling pathways mediated by FGF or EGF were determined by the comparisons of phosphorylation inhibitory efficacy using signaling inhibitors including kaempferol.

Results:

FGF acted as a tumor promoter. FGF induced cell proliferation by stimulation of G1/S cell cycle transition, and anchorage-independent cell transformation in JB6 Cl41 cells. FGF-induced FGFR phosphorylation was suppressed by kaempferol treatment in a dose dependent manner. Interestingly, FGF stimulation utilized a non-canonical signaling pathway to activate RSK2 and activating transcription factor (ATF)-1, which was not transduced by EGF stimulation. Importantly, kaempferol inhibited tyrosine phosphorylation of FGFR by FGF stimulation and nuclear accumulation of phospho-ATF-1 at Ser63. Moreover, although kaempferol, 4’-N-benzoyl staurosporine (PKC412), 2-(2’-amino-3’-methoxyphenyl)oxanaphthalen-4-one (PD98059) and 1,4-diamino-2,3-dicyano-1,4-bis(2-aminophenylthio)buta-diene (U0126) inhibited EGF-induced anchorage-independent cell transformation in JB6 Cl41 cells, FGF-induced cell transformation in soft agar was only inhibited by PKC412 and kaempferol, but not by PD98059 and U0126.

Conclusions:

FGF acts as a tumor promoter and dual inhibition of kaempferol on the kinase activities of FGFR3 and RSK2 suppresses the FGF-induced neoplastic cell transformation through a non-canonical signaling pathway which is not utilized by EGF stimulation.

Signals controlling un-differentiated states in embryonic stem and cancer cells: role of the phosphatidylinositol 3' kinase pathway

The capacity of embryonic stem (ES) cells to differentiate into cell lineages comprising the three germ layers makes them powerful tools for studying mammalian early embryonic development in vitro. The human body consists of approximately 210 different somatic cell types, the majority of which have limited proliferative capacity. However, both stem cells and cancer cells bypass this replicative barrier and undergo symmetric division indefinitely when cultured under defined conditions. Several signal transduction pathways play important roles in regulating stem cell development, and aberrant expression of components of these pathways is linked to cancer. Among signaling systems, the critical role of leukemia inhibitory factor (LIF) coupled to the Jak/STAT3 (signal transduction and activation of transcription-3) pathway in maintaining stem cell self-renewal has been extensively reviewed. This pathway additionally plays multiple roles in tumorigenesis. Likewise, the phosphatidylinositide 3-kinase (PI3K)/protein kinase B (PKB/Akt) pathway has been determined to play an important role in both stem cell maintenance and tumor development. This pathway is often induced in cancer with frequent mutational activation of the catalytic subunit of PI3K or loss of a primary PI3K antagonist, phosphatase and tensin homolog deleted on chromosome ten (PTEN). This review focusses on roles of the PI3K signal transduction pathway components, with emphasis on functions in stem cell maintenance and cancer. Since the PI3K pathway impinges on and collaborates with other signaling pathways in regulating stem cell development and/or cancer, aspects of the canonical Wnt, Ras/mitogen-activated protein kinase (MAPK), and TGF-β signaling pathways are also discussed.

Gonad RNA-specific qRT-PCR analyses identify genes with potential functions in schistosome reproduction such as SmFz1 and SmFGFRs

In the search for new strategies to fight schistosomiasis, the unique reproductive biology of Schistosoma mansoni has come into the focus of research. The development of the gonads and the ability of egg production are fundamental not only for continuing the life cycle but also for pathogenicity. Previous studies of schistosome biology demonstrated an influence of pairing on gonad development of the female and on gene expression profiles in both genders. Due to the limited access to specific tissues, however, most of these studies were done at the level of whole worms neglecting individual tissues that may be targets of pairing-dependent processes. Recently, we established a protocol allowing the isolation of testes and ovaries from adult S. mansoni. Here, we describe tissue-specific qRT-PCR analyses comparing transcript levels of selected genes on the basis of RNA from gonads and whole worms. Gene expression in ovary and testes was in some cases found to be significantly influenced by pairing, which was not traceable in whole worms. Among the candidate genes identified as regulated by pairing in gonads were the frizzled homolog SmFz1 and the two fibroblast growth factor receptor homologs SmFGFR-A and SmFGFR-B. First functional characterizations were done, including comparative qRT-PCR analyses, in situ-localization experiments, heterologous expression in Xenopus oocytes (SmFGFR-A/B), and inhibitor studies using the Fz/Dvl-pathway inhibitor 3289-8625, or BIBF1120 blocking FGFR-signaling. Besides confirming gonad localization and receptor functions, inhibitor-induced phenotypes were observed in vitro such as decreased egg production as well as drastic effects on gonad differentiation, morphology, embryogenesis, and survival of adult worms. In summary, these results emphasise the usefulness of tissue-specific qRT-PCRs for selection of candidate genes with important roles in reproduction, allowing subsequent studies to determine their suitability as drug targets.

Non-canonical activity of retinoic acid in epigenetic control of embryonic stem cell

Non-canonical cytoplasmic activities and signal transduction of retinoic acid (RA) expand RA's pleiotropic effects in coordinating the epigenome in embryonic stem cell (ESC). Examples include RA-bound cellular retinoic acid binding protein I, which activates ERK2. By engaging both cytosolic and nuclear mediators, RA can efficiently augment ESC's epigenome.

The implications of cancer stem cells for cancer therapy

Surgery, radiotherapy and chemotherapy are universally recognized as the most effective anti-cancer therapies. Despite significant advances directed towards elucidating molecular mechanisms and developing clinical trials, cancer still remains a major public health issue. Recent studies have showed that cancer stem cells (CSCs), a small subpopulation of tumor cells, can generate bulk populations of nontumorigenic cancer cell progeny through the self-renewal and differentiation processes. As CSCs are proposed to persist in tumors as a distinct population and cause relapse and metastasis by giving rise to new tumors, development of CSC-targeted therapeutic strategies holds new hope for improving survival and quality of life in patients with cancer. Therapeutic innovations will emerge from a better understanding of the biology and environment of CSCs, which, however, are largely unexplored. This review summarizes the characteristics, evidences and development of CSCs, as well as implications and challenges for cancer treatment.

Perspectives on cancer stem cells in osteosarcoma

Osteosarcoma is an aggressive pediatric tumor of growing bones that, despite surgery and chemotherapy, is prone to relapse. These mesenchymal tumors are derived from progenitor cells in the osteoblast lineage that have accumulated mutations to escape cell cycle checkpoints leading to excessive proliferation and defects in their ability to differentiate appropriately into mature bone-forming osteoblasts. Like other malignant tumors, osteosarcoma is often heterogeneous, consisting of phenotypically distinct cells with features of different stages of differentiation. The cancer stem cell hypothesis posits that tumors are maintained by stem cells and it is the incomplete eradication of a refractory population of tumor-initiating stem cells that accounts for drug resistance and tumor relapse. In this review we present our current knowledge about the biology of osteosarcoma stem cells from mouse and human tumors, highlighting new insights and unresolved issues in the identification of this elusive population. We focus on factors and pathways that are implicated in maintaining such cells, and differences from paradigms of epithelial cancers. Targeting of the cancer stem cells in osteosarcoma is a promising avenue to explore to develop new therapies for this devastating childhood cancer.

Fibroblast growth factor regulates human neuroectoderm specification through ERK1/2-PARP-1 pathway

Fibroblast growth factor (FGF) signaling and PAX6 transcription are required for neuroectoderm specification of human embryonic stem cells (hESCs). In this study, we asked how FGF signaling leads to PAX6 transcription and neuroectoderm specification from hESCs. Under a chemically defined medium, FGF inhibition blocked phosphorylation of extracellular signal-regulated kinase 1/2 (ERK 1/2) with a significant reduction of PAX6-expressing neuroepithelia, indicating that FGF regulates neural induction through ERK1/2 activation. Activation of FGF-ERK1/2 pathway was necessary for the activity of poly(ADP-ribose) polymerase-1 (PARP-1), a conserved nuclear protein catalyzing polymerization of ADP-ribose units. Pharmacological inhibition and genetic ablation of PARP-1 inhibited neural induction from hESCs, suggesting that FGF-ERK1/2 signal pathway regulates neuroectoderm specification through regulating PARP-1 activity. Furthermore, FGF-ERK1/2-PARP-1 cascade regulated the expression of PAX6, a transcription determinant of human neuroectoderm. Together, we propose that FGF regulates hESC neural specification through the ERK1/2-PARP-1 signaling pathway.

Effects of glucocorticoid receptor small interfering RNA delivered using poly lactic-co-glycolic acid microparticles on proliferation and differentiation capabilities of human mesenchymal stromal cells

Bone marrow-derived mesenchymal stem cells (MSC) are a potential attractive source of cells for stem cell-based tissue regeneration, but the small number and reduced capabilities of MSC proliferation and differentiation due to in vitro replicative senescence and donor-associated pathophysiological factors, including age and estrogen depletion, severely restrict their potential usefulness in clinical applications. Glucocorticoids (GC) are well-known steroid hormones that regulate MSC proliferation and differentiation, but the defined effects and underlying mechanisms of endogenous glucocorticoids on MSC characteristics are not understood. This study investigated the effects of the blockage of endogenous GC using glucocorticoid receptor (GR) small interfering RNA (siRNA) delivered using biodegradable poly(lactic-co-glycolic acid) (PLGA) microparticles on proliferation and differentiation capabilities of human MSC in vitro. The results show that we can prepare PLGA microparticles as a delivery system for GR siRNA and maintain release of siRNA up to 40 days in vitro. Transfection of GR siRNA significantly downregulates GR and upregulates the expression of fibroblast growth factor-2 and Sox-11 of human MSC. MSC that have proliferated with endogenous GC blocked in vitro have greater proliferation rates and exhibit upregulated expression of osteogenic markers (alkaline phosphatase and core binding factor alpha 1) under differentiation stimulation after 1 week. Under adipogenic differentiation, MSC proliferated in vitro with siRNA transfection, resulting in significantly lower adipogenic markers (peroxisome proliferator-activated receptor and lipoprotein lipase) than controls. In conclusion, PLGA particles can serve as a tool for delivery of GR siRNA to effectively block the effects of endogenous GC on MSC, which has the potential to improve the capabilities of human MSC for clinical application by preventing replicative senescence.

FGF-2 regulates cell proliferation, migration, and angiogenesis through an NDY1/KDM2B-miR-101-EZH2 pathway

The histone H3K27 methyltransferase EZH2 plays an important role in oncogenesis, by mechanisms that are incompletely understood. Here, we show that the JmjC domain histone H3 demethylase NDY1 synergizes with EZH2 to silence the EZH2 inhibitor miR-101. NDY1 and EZH2 repress miR-101 by binding its promoter in concert, via a process triggered by upregulation of NDY1. Whereas EZH2 binding depends on NDY1, the latter binds independently of EZH2. However, both are required to repress transcription. NDY1 and EZH2 acting in concert upregulate EZH2 and stabilize the repression of miR-101 and its outcome. NDY1 is induced by FGF-2 via CREB phosphorylation and activation, downstream of DYRK1A, and mediates the FGF-2 and EZH2 effects on cell proliferation, migration, and angiogenesis. The FGF-2-NDY1/EZH2-miR-101-EZH2 axis described here was found to be active in bladder cancer. These data delineate an oncogenic pathway that functionally links FGF-2 with EZH2 via NDY1 and miR-101.

The relationship between early embryo development and tumourigenesis

With the recent substantial progress in developmental biology and cancer biology, the similarities between early embryo development and tumourigenesis, as well as the important interaction between tumours and embryos become better appreciated. In this paper, we review in detail the embryonic origin of tumour, and the similarities between early embryo development and tumourigenesis with respect to cell invasive behaviours, epigenetic regulation, gene expression, protein profiling and other important biological behaviours. Given an improved understanding of the relationship between early embryo development and tumourigenesis, now we have better and broader resources to attack cancer from the perspective of developmental biology and develop next generation of prognostic and therapeutic approaches for this devastating disease.

Fibroblast growth factor 2 and platelet-derived growth factor, but not platelet lysate, induce proliferation-dependent, functional class II major histocompatibility complex antigen in human mesenchymal stem cells

OBJECTIVE

To document the specificity and the mechanism of induction of a novel class II major histocompatibility complex (MHC) antigen by mitogenic growth factors in human mesenchymal stem cells (MSCs) expanded in vitro for translational applications.

METHODS

Expression of class II MHC molecules was measured in human MSCs and differentiated cells expanded in the presence of fibroblast growth factor 2 (FGF-2), platelet-derived growth factor BB (PDGF-BB), human platelet lysate, or interferon-γ (IFNγ). The roles of cell proliferation and growth factor-induced signaling pathways were investigated as well as the class II MHC assembly machinery and functional capacity.

RESULTS

FGF-2 and, to a lesser extent, PDGF-BB induced in adult human MSCs the expression of HLA-DR (normally induced by inflammatory cytokines), which was able to stimulate CD4+ T cells via superantigen binding. In contrast to IFNγ, FGF induced HLA-DR expression only in human MSCs proliferating under its mitogenic effect and not in mouse MSCs or in differentiated human cells. Although it induced cell proliferation, human platelet lysate did not cause HLA-DR expression in human MSCs. HLA-DR expression occurred following FGF-specific binding to its receptor(s), mainly FGF receptor 1, without inducing IFNγ or tumor necrosis factor α expression. Both MAPK/ERK-1/2 and phosphatidylinositol 3-kinase/Akt controlled cell proliferation and HLA-DR expression, but only MAPK/ERK-1/2 controlled the induction of the class II MHC transcription activator protein CIITA, the major determinant of HLA-DR transcription.

CONCLUSION

The induction of functional HLA-DR in proliferating progenitor MSCs is a property of human MSCs that have been expanded with mitogenic growth factors. This has potential biologic significance in the regulation and/or protection of progenitor cell subpopulations under sustained mitogenic proliferation and needs to be taken into account when expanding MSCs for use in in vivo applications.