MIR-448 Regulates MAGEA6/AMPK Signaling Pathway in Hepatocellular Carcinoma Tumor Stem Cells

Objective: To explore the role of miR-448 in regulating MAGEA6/AMPK signaling pathway in the biological study of hepatocellular carcinoma (HCC) tumor stem cells. Methods: Using the database, the hepatocellular carcinoma related expression chips were obtained and the regulatory mirnas of candidate genes were predicted, and the predicted results were analyzed. The effects of miR-448 and MAGEA6 on the pellet formation rate and clone formation rate of hepatocellular carcinoma stem cells were detected by immunofluorescence identification of stem cell markers and light microscope counting method. The effects of miR-448 and MAGEA6 on migration and invasion of hepatocellular carcinoma stem cells were detected by scratch and Transwell assay. Dual luciferase reporter assay to verify whether miR-448 targets MAGEA6. The expression and influence of miR-448 on MAGEA6 and AMPK pathway were detected by qRT-PCR and Western blot. Results: It was found that miR-448 may directly regulate the expression of MAGEA6. Overexpression of miR-448 inhibited the characteristics, proliferation, migration, and invasion of hepatocellular carcinoma stem cells in vitro, as well as the ability of xenograft tumor formation in vivo. However, inhibition of miR-448 showed opposite results. In addition, miR-448 directly targets MAGEA6 and regulates AMPK signaling. Silencing MAGEA6 and adding AMPK activator further verified that miR-448 activated AMPK signaling pathway by targeting MAGEA6, thus affecting characteristics, proliferation, migration and invasion of hepatoma stem cells. Conclusions: Our results reveal that miR-448 activates AMPK signaling pathway by targeting MAGEA6, thereby affecting characteristics, proliferation, migration and invasion of hepatoma stem cells. It is suggested that overexpression of miR-448 may be a new therapeutic strategy for hepatocellular carcinoma.

Similarity on neural stem cells and brain tumor stem cells in transgenic brain tumor mouse models

Although it is believed that glioma is derived from brain tumor stem cells, the source and molecular signal pathways of these cells are still unclear. In this study, we used stable doxycycline-inducible transgenic mouse brain tumor models （c-myc/SV40Tag＋/Tet-on＋） to explore the malignant trans- formation potential of neural stem cells by observing the differences of neural stem cells and brain tumor stem cells in the tumor models. Results showed that chromosome instability occurred in brain tumor stem cells. The numbers of cytolysosomes and autophagosomes in brain tumor stem cells and induced neural stem cells were lower and the proliferative activity was obviously stronger than that in normal neural stem cells. Normal neural stem cells could differentiate into glial fibrillary acidic protein-positive and microtubule associated protein-2-positive cells, which were also negative for nestin. However, glial fibrillary acidic protein/nestin, microtubule associated protein-2/nestin, and glial fibrillary acidic protein/microtubule associated protein-2 double-positive cells were found in induced neural stem cells and brain tumor stem cells. Results indicate that induced neural stem cells are similar to brain tumor stem cells, and are possibly the source of brain tumor stem cells.

Research Progress in the Regulation of Tumor Cells and Tumor Stem Cells at Multiple Targets by Antrodia camphorata

Extensive in vitro and in vivo research reveals multiple intracellular molecular targets of Antrodia camphorata,and these targets affect growth,apoptosis,angiogenesis,invasion and metastasis of cells.These targets include tumor suppressor,cell cycle regulator,transcription factor,angiogenesis and metastasis factor,apoptosis and survival regulator,etc.Additionally,more and more attention has been paid to the molecular mechanism of A.camphorata on the regulation of tumor stem cells.Meanwhile,there is evidence that the immunoregulation of A.camphorata is enhanced,which may lead cell cycle arrest or apoptosis.In this paper,molecular mechanism of tumor cells and tumor stem cells regulated at multiple targets by A.camphorata in vitro and in vivo in the past decade is summarized.

Experimental study on dendritic cells pulsed with brain tumor stem cells for immunotherapy of glioma

Objective To investigate the effect of dendritic cells pulsed with brain tumor stem cells which are used to treat on intracranial glioma. Methods We obtained murine brain tumor stem cells by grow ing C6 cells in epidermal grow th factor/basic fibroblast grow th factor w ithout serum.Dendritic cells isolated from rat bone marrow w ere pulsed w ith BTSCs. Rat brain

Differentiation profile of brain tumor stem cells:a comparative study with neural stem cells

大脑肿瘤干细胞(BTSC ) 的区别侧面的理解，在肿瘤房间人口之中的关键的，将通过有神经干细胞(NSC ) 的比较借卓见进 glioma 的起源并且最终产出新途径与这难处理的疾病作斗争。这里，我们从外科的 glioma 标本的有教养、净化的 BTSC 和 NSCsfrom 人的胎儿的大脑织物，并且进一步分析了他们的细胞的生物行为，他们的特别区别性质。是期望，区分进成熟神经显型的 NSC。然而， BTSC 展出了的 Inthe 一样的区别状况区分了差别。词法上，房间变得变平并且属于第一个星期，但是逐渐地此后聚集了并且改过漂浮的肿瘤范围。在相应时期期间，无差别的房间标记 CD133 和巢在的表示率在 BTSC 不停地减少，但是 1 个星期以后，他们重获上升趋势。有趣地，区分的房间标记 GFAP 和 beta-tubulinIIIshowed 表示变化逆到无差别的房间标记的。总起来说， BTSCswere 揭示了拥有一个能力抵抗区别，它实际上代表 glioma 的恶意的行为。

Isolation and biological analysis of tumor stem cells from pancreatic adenocarcinoma

AIM: To explore the method of isolation and biological analysis of tumor stem cells from pancreatic adenocarcinoma cell line PANC-1. METHODS: The PANC-1 cells were cultured in Dulbecco modified eagle medium F12 (1:1 volume) (DMEM-F12) supplemented with 20% fetal bovine serum (FBS). Subpopulation cells with properties of tumor stem cells were isolated from pancreatic adenocarcinoma cell line PANC-1 according to the cell surface markers CD44 and CD24 by flow cytometry. The proliferative capability of these cells in vitro were estimated by 3-[4,5-dimehyl-2-thiazolyl]-2,5-diphenyl-2H-tetrazolium bromide (MTT) method. And the tumor growth of different subpopulation cells which were injected into the hypodermisof right and left armpit of nude mice was studied,and expression of CD44 and CD24 of the CD44+CD24+ cell-formed nodules and PANC-1 cells were detected by avidin-biotin-peroxidase complex (ABC) immunohistochemical staining. RESULTS: The 5.1%-17.5% of sorted PANC-1 cells expressed the cell surface marker CD44,57.8% -70.1% expressed CD24,only 2.1%-3.5% of cells were CD44+ CD24+. Compared with CD44-CD24-cells,CD44+CD24+ cells had a lower growth rate in vitro. Implantation of 104 CD44-CD24-cells in nude mice showed no evidenttumor growth at wk 12. In contrast,large tumors were found in nude mice implanted with 103 CD44+CD24+ cells at wk 4 (2/8),a 20-fold increase in tumorigenic potential (P < 0.05 or P < 0.01). There was no obvious histological difference between the cells of the CD44+CD24+ cell-formed nodules and PANC-1 cells. CONCLUSION: CD44 and CD24 may be used as the cell surface markers for isolation of pancreatic cancer stem cells from pancreatic adenocarcinoma cell line PANC-1. Subpopulation cells CD44+CD24+ have properties of tumor stem cells. Because cancer stem cells are thought to be responsible for tumor initiation and its recurrence after an initial response to chemotherapy,it may be a very promising target for new drug development.

The cultivation and identification of tumor stem cells from neuroblastoma derived tumor spheres

Background and Objective: Since the proposal of the tumor stem cell hypothesis, considerable interest has been devoted to the isolation and purification of tumor stem cells. Tumor stem cell enrichment from primary tumor derived cell spheres has been demonstrated in specific, serum-free media. This goal of this study is to establish a method of cultivating floating tumor spheres from neuroblastoma cells and to confirm that neuroblastoma spheres are rich in tumor stem cells. Methods: Bone marrow aspirates were obtained from pediatric patients diagnosed with stage IV neuroblastoma. Primary tumor cells were isolated and cultivated in serum-free, stem cell-selective medium. Single sphere-forming cells were cultivated under serum-free conditions; their cloning efficiency and monoclonal tumor sphere formation rates were calculated. The expression of stem cell marker genes Oct-4 and Bmi-1 was detected by RT-PCR in sphere-forming cells and parental neurolastoma cells. Sphere-forming cells were injected into the armpit of nude mice with subsequent assessment for tumor growth. Sphere-forming cells were cultivated in differentiation medium containing 5 μmol/L 13-cis retinoic acid; changes in cell morphology were observed. Results: Neuroblastoma cells formed non-adherent neurospheres under serum-free, stem cell-selective conditions after a period of 4 to 6 days. A single cell dissociated from a neurosphere could reform a monoclonal sphere; cloning efficiency and monoclonal sphere formation rates were 55.3% and 26.3%, respectively. RT-PCR results revealed heightened tumor sphere expression of Oct-4 and Bmi-1 as compared with parental tumor cells. Fourteen days after injection of 104 sphere-forming cells into nude mice, a neuroblastoma xenograft formed. Treatment of sphere-forming cells with 13-cis retinoic acid induced a gradual differentiation to neuronal cell morphology. Conclusions: Neuroblastoma derived tumor spheres enrich tumor stem cells and the cultivation of primary neuroblastoma cells in serum-free, stem cell-selective medium is an effective method to dissociate and purify tumor stem cells in vitro.

Tumor stem cell, or its niche, which plays a primary role in tumorigenesis?

Cancer research over the past decades has focused on neoplastic cells, or a fraction of them, i.e. tumor stem cells, as the ultimate causes of tumorigenesis. However, during recent years, scientists have come to realize that tumorigenesis is not a solo act of neoplastic cells, but rather a cooperative process in which the roles of numerous types of non-neoplastic cells should be recognized. These tumor-residing non-neoplastic cells constitute the so-called tumor-associated stroma, which in certain cases even greatly surpasses the neoplastic cellular compartment that was previously thought of as a sole determiner leading to a seemingly autonomous growth pattern. In this review, we summarize several recent research highlights that have unveiled many previously unappreciated roles for microenvironmental factors, especially during the initiation stage of tumorigenesis. It is becoming increasingly clear that the stroma’s regulatory effects constitute not only an essential force for maintaining tumor growth, but also primary causes initiating tumorigenesis.

MicroRNAs in tumor stem cells

Micro RNAs(mi RNAs) are a class of non-coding RNAs that are believed to have a significant role in tumorigenesis and cancer metastasis. Cancer stem cells play a major role in tumor recurrence, metastasis, and drug resistance. Research has shown that mi RNAs can promote or inhibit the stemness of cancer stem cells and regulate the differentiation and self-renewal of cancer stem cells. In this article, the phenotype and regulatory mechanisms of mi RNAs in cancer stem cells will be described, together with an explanation of their potential role in tumor diagnosis and treatment.

Cancer stem cell plasticity and tumor hierarchy

The origins of the complex process of intratumoral heterogeneity have been highly debated and different cellular mechanisms have been hypothesized to account for the diversity within a tumor. The clonal evolution and cancer stem cell(CSC) models have been proposed as drivers of this heterogeneity. However, the concept of cancer stem cell plasticity and bidirectional conversion between stem and non-stem cells has added additional complexity to these highly studied paradigms and may help explain the tumor heterogeneity observed in solid tumors. The process of cancer stem cell plasticity in which cancer cel s harbor the dynamic ability of shifting from a non-CSC state to a CSC state and vice versa may be modulated by specific microenvironmental signals and cellular interactions arising in the tumor niche. In addition to promoting CSC plasticity, these interactions may contribute to the cellular transformation of tumor cells and affect response to chemotherapeutic and radiation treatments by providing CSCs protection from these agents. Herein, we review the literature in support of this dynamic CSC state, discuss the effectors of plasticity, and examine their role in the development and treatment of cancer.

An overview of the role of cancer stem cells in spine tumors with a special focus on chordoma

Primary malignant tumors of the spine are relatively rare, less than 5% of all spinal column tumors. However, these lesions are often among the most difficult to treat and encompass challenging pathologies such as chordoma and a variety of invasive sarcomas. The mechanisms of tumor recurrence after surgical intervention, as well as resistance to radiation and chemotherapy, remain a pervasive and costly problem. Recent evidence has emerged supporting the hypothesis that solid tumors contain a sub-population of cancer cells that possess characteristics normally associated with stem cells. Particularly, the potential for long-term proliferation appears to be restricted to subpopulations of cancer stem cells(CSCs) functionally defined by their capacity to self-renew and give rise to differentiated cells that phenotypically recapitulate the original tumor, thereby causing relapse and patient death. These cancer stem cells present a unique opportunity to better understand the biology of solid tumors in general, as well as targets for future therapeutics. The general objective of the current study is to discuss the fundamental concepts for understanding the role of CSCs with respect to chemoresistance, radioresistance, special cell surface markers, cancer recurrence and metastasis intumors of the osseous spine. This discussion is followed by a specific review of what is known about the role of CSCs in chordoma, the most common primary malignant osseous tumor of the spine.

Single-cell analysis of tumors:Creating new value for molecular biomarker discovery of cancer stem cells and tumor-infiltrating immune cells

Biomarker-driven individualized treatment in oncology has made tremendous progress through technological developments, new therapeutic modalities and a deeper understanding of the molecular biology for tumors, cancer stem cells and tumor-infiltrating immune cells. Recent technical developments have led to the establishment of a variety of cancer-related diagnostic, prognostic and predictive biomarkers. In this regard, different modern OMICs approaches were assessed in order to categorize and classify prognostically different forms of neoplasia. Despite those technical advancements, the extent of molecular heterogeneity at the individual cell level in human tumors remains largely uncharacterized. Each tumor consists of a mixture of heterogeneous cell types. Therefore, it is important to quantify the dynamic cellular variations in order to predict clinical parameters, such as a response to treatment and or potential for disease recurrence. Recently, single-cell based methods have been developed to characterize the heterogeneity in seemingly homogenous cancer cell populations prior to and during treatment. In this review, we highlight the recent advances for single-cell analysis and discuss the challenges and prospects for molecular characterization of cancer cells, cancer stem cells and tumor-infiltrating immune cells.

Circulating tumor and cancer stem cells in hepatitis C virusassociated liver disease

AIM:To assess the role of circulating tumor cells(CTCs)and cancer stem cells(CSCs)in hepatitis C virus(HCV)-associated liver disease.METHODS:Blood and/or tissue samples were obtained from HCV(genotype 4)-associated hepatocellularcarcinoma patients(HCC;n=120),chronic hepatitis C patients(CH;n=30)and 33 normal control subjects(n=33).Serum levels of alpha-fetoprotein(AFP),alkaline phosphatase,and alanine and aspartate aminotransferases were measured.Cytokeratin 19(CK19)monoclonal antibody was used to enumerate CTCs,and CD133 and CD90 were used to enumerate CSCs by flow cytometry.The expression levels of the CSCs markers(CD133 and CD90)as well as telomerase,melanoma antigen encoding gene 1(MAGE1)and MAGE3 were assessed by RTPCR and quantitative real-time polymerase chain reactions.The number of CTCs and/or the expression levels of CK19,CD133,telomerase,MAGE1 and MAGE3 were correlated to the standard clinicopathologic prognostic factors and disease progression.RESULTS:Levels of AFP,alkaline phosphatase and aspartate aminotransferase were significantly different among the HCC,CH and control groups(P<0.001),whereas alanine aminotransferase differed significantly between patient(HCC and CH)and control groups(P<0.001).At the specified cutoff values determine by flow cytometry,CK19(49.8),CD90(400)and CD133(73)were significantly higher in the blood of HCC patients compared to those in the CH and control groups(P<0.001).On the other hand,CD133 at a 69.5 cutoff was significantly higher in the CH compared to the control group(P≤0.001).Telomerase,MAGE1 and MAGE3RNA were expressed in 55.71%,60.00%and 62.86%of the HCC patients,respectively,but were not detected in patients in the CH or control groups,which were statistically significant(Ps<0.001).The expression levels of telomerase,CD90,MAGE3,CD133 and CK19 were all significantly associated with high tumor grade and advanced stage in HCC patients(all P s<0.05).CONCLUSION:CTC counts and AFP,CK19,telomerase,and MAGE1/MAGE3 expression predict disease progression in patients with HCV,whereas telomerase,MAGE3,CD90,CD133 and CK19 are prognostic mark-

Stem cell factor-mediated wild-type KIT receptor activation is critical for gastrointestinal stromal tumor cell growth

AIM: To clarify the biological role of stem cell factor (SCF)-mediated wild-type KIT receptor activation in gastrointestinal stromal tumor (GIST) growth. METHODS: The co-expression of wild-type KIT receptor and SCF was evaluated in 51 GIST samples using mutation analysis and immunohistochemistry, and the results were correlated with clinicopathological param- eters, including the mitotic count, proliferative index (Ki-67 immunohistochemical staining), mitotic index (phospho-histone H3 immunohistochemical staining) and apoptotic index (terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling). Using primary cultured GIST cells, the effect of SCF-mediated wild-type KIT receptor activation was determined by western blotting, methyl thiazolyl tetrazolium (MTT), and apoptosis assays. RESULTS: We found that wild-type KIT receptor and SCF protein were expressed in 100% and 76.5% of the 51 GIST samples, respectively, and the co-expression of wild-type KIT receptor and SCF was associated with known indicators of poor prognosis, including larger tumor size (P = 0.0118), higher mitotic count (P = 0.0058), higher proliferative index (P = 0.0012), higher mitotic index (P = 0.0282), lower apoptosis index (P = 0.0484), and increased National Institutes of Health risk level (P = 0.0012). We also found that the introduction of exogenous SCF potently increased KIT kinase activity, stimulated cell proliferation (P < 0.01) and inhibited apoptosis (P < 0.01) induced by serum starvation, while a KIT immunoblocking antibody suppressed proliferation (P = 0.01) and promoted apoptosis (P < 0.01) in cultured GIST cells. CONCLUSION: SCF-mediated wild-type KIT receptor activation plays an important role in GIST cell growth. The inhibition of SCF-mediated wild-type KIT receptor activation may prove to be particularly important for GIST therapy.

Xiaotan Sanjie decoction attenuates tumor angiogenesis by manipulating Notch-1-regulated proliferation of gastric cancer stem-like cells

AIM: To determine the underlying mechanisms of action and influence of Xiaotan Sanjie(XTSJ) decoction on gastric cancer stem-like cells(GCSCs). METHODS: The gastric cancer cell line MKN-45 line was selected and sorted by FACS using the cancer stem cell marker CD44; the stemness of these cells was checked in our previous study. In an in vitro study, the expression of Notch-1, Hes1, Vascular endothelial growth factor(VEGF), and Ki-67 in both CD44-positive gastric cancer stem-like cells(GCSCs) and CD44-negative cells was measured by Western blot. The effect of XTSJ serum on cell viability and on the above markers was measured by MTT assay and Western blot, respectively. In an in vivo study, the ability to induce angiogenesis and maintenance of GCSCs in CD44-positive-MKN-45- and CD44-negative-engrafted mice were detected by immunohistochemical staining using markers for CD34 and CD44, respectively. The role of XTSJ decoction in regulating the expression of Notch-1, Hes1, VEGF and Ki-67 was measured by Western blot and real-time polymerase chain reaction.RESULTS: CD44+ GCSCs showed more cell proliferation and VEGF secretion than CD44-negative cells in vitro, which were accompanied by the high expression of Notch-1 and Hes1 and positively associated with tumor growth(GCSCs vs CD44-negative cells, 2.72 ± 0.25 vs 1.46 ± 0.16, P < 0.05) and microvessel density(MVD)(GCSCs vs CD44-negative cells, 8.15 ± 0.42 vs 3.83 ± 0.49, P < 0.001) in vivo. XTSJ decoction inhibited the viability of both cell types in a dose-dependent manner in vitro. Specifically, a significant difference in the medium-(82.87% ± 6.53%) and high-dose XTSJ groups(77.43% ± 7.34%) was detected at 24 h in the CD44+ GCSCs group compared with the saline group(95.42% ± 5.76%) and the low-dose XTSJ group(90.74% ± 6.57%)(P < 0.05). However, the efficacy of XTSJ decoction was reduced in the CD44- groups; significant differences were only detected in the high-dose XTSJ group at 48 h(78.57% ± 6.94%) and 72 h(72.12% ± 7.68%) when compared with the other CD44- groups(P < 0.05). Notably, these differences were highly consistent with the Notch-1, Hes1, VEGF and Ki-67 expression in these cells. Similarly, in vivo, XTSJ decoction inhibited tumor growth in a dose-dependent manner. A significant difference was observed in the medium(1.76 ± 0.15) and high-dose XTSJ(1.33 ± 0.081) groups compared with the GCSCs control group(2.72 ± 0.25) and the low-dose XTSJ group(2.51 ± 0.25)(P < 0.05). We also detected a remarkable decrease of MVD in the medium-(7.10 ± 0.60) and high-dose XTSJ(5.99 ± 0.47) groups compared with the GCSC control group(8.15 ± 0.42) and the low-dose XTSJ group(8.14 ± 0.46)(P < 0.05). Additionally, CD44 expression was decreased in these groups [medium-(4.43 ± 0.45) and high-dose XTSJ groups(3.56 ± 0.31) vs the GCSC control(5.96 ± 0.46) and low dose XTSJ groups(5.91 ± 0.38)](P < 0.05). The significant differences in Notch-1, Hes1, VEGF and Ki-67 expression highly mirrored the results of XTSJ decoction in inhibiting tumor growth, MVD and CD44 expression.CONCLUSION: Notch-1 may play an important role in regulating the proliferation of GCSCs; XTSJ decoction could attenuate tumor angiogenesis, at least partially, by inhibiting Notch-1.

Differentiation of Mesenchymal Stem Cells into Hepatocyte-Like Cells by Autologous Serum after Radiofrequency Ablation of Liver Tumor

Mesenchymal stem cells?(MSCs) have been shown to differentiate into liver cells in serum of part-resection liver, but it was hardly feasible in clinical use. Our studies revealed that MSCs could differentiate into hepatocyte-like cells in autologous serum after radiofrequency ablation (RFA) therapy of the liver tumor. Rabbits with liver tumor subsequently treated with RFA therapy. Serum was collected from those rabbits before RFA therapy and 72 hours after RFA therapy. MSCs were isolated from each rabbit’s bone marrow and cultured in DMEM medium containing the following different supplements: 30% fetal calf serum (FCS group), 30% rabbit autologous serum (AS group) or 30% autologous serum after RFA treatment of the liver tumor (ASRF group), observed by electron microscopy, flow cytometry, immunofluorescence. Seven days later, most of the spindle-shaped MSCs in the ASRF group transformed into polygon or round-shaped cells resembling hepatocytes, and the percentage in S/G2/M phase was higher than in the FCS or AS groups. Fourteen days later, slender microvilli, cell-cell junction structures and cholangiole emerged in the cells belonging to the ASRF group, the expression of albumin and CK18 was observed only in the differentiated cells from the ASRF group. These changes were not observed in the FCS group or the AS group. This study may provide a potential cell source and culture process for clinical application in liver injury treatment.

Stemness Gene Profiles of Circulating Tumor Cells

Circulating tumor cells (CTCs) are a population of tumor-derived cells that detach from the primary tumor and initiate metastasis. However, the mechanisms of this process are still unknown. This phenomenon renders CTCs as a valuable resource for prognosis and diagnosis of cancer. The involvement of stemness transcription factors and markers, such as NANOG, OCT3/4, CD34, NESTIN, and SOX2, in metastasis initiation has been studied recently because their abnormally elevated expression in cancer cells may be highly important in understanding tumor initiation. This study analyzed the genetic profiles of the above genes in CTCs derived from patients with different types of cancer. Blood samples were randomly collected from 71 cancer patients with various cancer types. CTCs were isolated using enrichment protocols and RNA was extracted. RT-qPCR was performed in triplicate using ACTB as the reference gene. The statistical analysis was performed among the ΔCts of the samples using parametric and non-parametric methods. The molecular analysis revealed that the expression of each gene was different than the others. When each type of cancer was analyzed separately, the gene expression profile was not always the same. It is noteworthy that, in all cases, the gene expression of NESTIN differed from that of transcription factors. According to the above data, gene expression profiles might be used as a potential biomarker or constitute a gene signature.

Training stem cells for treatment of malignant brain tumors

The treatment of malignant brain tumors remains a challenge. Stem cell technology has been applied in the treatment of brain tumors largely because of the ability of some stem cells to infiltrate into regions within the brain where tumor cells migrate as shown in preclinical studies. However, not all of these efforts can translate in the effective treatment that improves the quality of life for pa-tients. Here, we perform a literature review to identify the problems in the field. Given the lack of efficacy of most stem cell-based agents used in the treatment of malignant brain tumors, we found that stem cell distribution(i.e., only a fraction of stem cells applied capable of targeting tumors) are among the limiting factors. We provide guidelines for potential improvements in stem cell distribution. Specifically, we use an engineered tissue graft platform that replicates the in vivo microenvironment, and provide our data to validate that this culture platform is viable for producing stem cells that have better stem cell distribution than with the Petri dish culture system.

Hematopoietic stem cell-derived adipocytes and fibroblasts in the tumor microenvironment

The tumor microenvironment(TME) is complex and constantly evolving. This is due, in part, to the crosstalk between tumor cells and the multiple cell types that comprise the TME, which results in a heterogeneous population of tumor cells and TME cells. This review will focus on two stromal cell types, the cancerassociated adipocyte(CAA) and the cancer-associated fibroblast(CAF). In the clinic, the presence of CAAs and CAFs in the TME translates to poor prognosis in multiple tumor types. CAAs and CAFs have an activated phenotype and produce growth factors, inflammatory factors, cytokines, chemokines, extracellular matrix components, and proteases in an accelerated and aberrant fashion. Through this activated state, CAAs and CAFs remodel the TME, thereby driving all aspects of tumor progression, including tumor growth and survival, chemoresistance, tumor vascularization, tumor invasion, and tumor cell metastasis. Similarities in the tumorpromoting functions of CAAs and CAFs suggest that a multipronged therapeutic approach may be necessary to achieve maximal impact on disease. While CAAs and CAFs are thought to arise from tissues adjacent to the tumor, multiple alternative origins for CAAs and CAFs have recently been identified. Recent studies from our lab and others suggest that the hematopoietic stem cell, through the myeloid lineage, may serve as a progenitor for CAAs and CAFs. We hypothesize that the multiple origins of CAAs and CAFs may contribute to the heterogeneity seen in the TME. Thus, a better understanding of the origin of CAAs and CAFs, how this origin impacts their functions in the TME, and thetemporal participation of uniquely originating TME cells may lead to novel or improved anti-tumor therapeutics.

Are Cancer Stem Cells the Sole Source of Tumor?

Tumors are believed to consist of a heterogeneous population of tumor ceils originating from rare cancer stem cells （CSCs）. However, emerging evidence suggests that tumor may also origi- nate from non-CSCs. To support this viewpoint, we are here to present definitive evidence indicating that the number of tumorigenic tumor cells is greater than that of CSCs in tumor, and tumor can also derive from non-CSCs. To achieve this, an idealized mathematical model was employed in the pre- sent study and theoretical calculation revealed that non-CSCs could initiate the occurrence of tumor if their proliferation potential was adequate. Further, experimental studies demonstrated that 17.7%, 38.6% and 5.2% of tumor cells in murine B16 solid melanoma, H22 hepatoma and Lewis lung carci2 noma, respectively, were potentially tumorigenic. Thus, based on the aforementioned findings, we propose that the scarce CSCs, if exist, are not the sole source of a tumor.