Hedgehog signaling regulates brain tumor-initiating cell proliferation and portends shorter survival for patients with PTEN-coexpressing glioblastomas

The identification of brain tumor stem-like cells (BTSCs) has implicated a role of biological self-renewal mechanisms in clinical brain tumor initiation and propagation. The molecular mechanisms underlying the tumor-forming capacity of BTSCs, however, remain unknown. Here, we have generated molecular signatures of glioblastoma multiforme (GBM) using gene expression profiles of BTSCs and have identified both Sonic Hedgehog (SHH) signaling-dependent and -independent BTSCs and their respective glioblastoma surgical specimens. BTSC proliferation could be abrogated in a pathway-dependent fashion in vitro and in an intracranial tumor model in athymic mice. Both SHH-dependent and -independent brain tumor growth required phosphoinositide 3-kinase-mammalian target of rapamycin signaling. In human GBMs, the levels of SHH and PTCH1 expression were significantly higher in PTEN-expressing tumors than in PTEN-deficient tumors. In addition, we show that hyperactive SHH-GLI signaling in PTEN-coexpressing human GBM is associated with reduced survival time. Thus, distinct proliferation signaling dependence may underpin glioblastoma propagation by BTSCs. Modeling these BTSC proliferation mechanisms may provide a rationale for individualized glioblastoma treatment.

Vaccination elicits correlated immune and clinical responses in glioblastoma multiforme patients

Cancer vaccine trials have failed to yield robust immune-correlated clinical improvements as observed in animal models, fueling controversy over the utility of human cancer vaccines. Therapeutic vaccination represents an intriguing additional therapy for glioblastoma multiforme (GBM; grade 4 glioma), which has a dismal prognosis and treatment response, but only early phase I vaccine trial results have been reported. Immune and clinical responses from a phase II GBM vaccine trial are reported here. IFN-gamma responsiveness was quantified in peripheral blood of 32 GBM patients given therapeutic dendritic cell vaccines. Posttreatment times to tumor progression (TTP) and survival (TTS) were compared in vaccine responders and nonresponders and were correlated with immune response magnitudes. GBM patients (53%) exhibited >or=1.5-fold vaccine-enhanced cytokine responses. Endogenous antitumor responses of similar magnitude occurred in 22% of GBM patients before vaccination. Vaccine responders exhibited significantly longer TTS and TTP relative to nonresponders. Immune enhancement in vaccine responders correlated logarithmically with TTS and TTP spanning postvaccine chemotherapy, but not with initial TTP spanning vaccination alone. This is the first report of a progressive correlation between cancer clinical outcome and T-cell responsiveness after therapeutic vaccination in humans and the first tracing of such correlation to therapeutically exploitable tumor alteration. As such, our findings offer unique opportunities to identify cellular and molecular components of clinically meaningful antitumor immunity in humans.

Dendritic cell immunotherapy for malignant gliomas

The prognosis for patients with malignant gliomas remains poor despite advances in surgical technique, chemotherapy and radiation therapy. Median survival for glioblastoma multiforme, the most aggressive and deadliest form of brain cancer, remains only fifteen months even after optimal treatment with surgical resection followed by chemoradiation therapy. The grim prognosis can be attributed to the infiltrative nature of the disease, a central nervous system microenvironment that can escape immune surveillance and resistance of the tumor to chemotherapy. In recent trials, dendritic cells have demonstrated an ability to promote an effective anti-tumor immune response and sensitize glioma cells to chemotherapy. This review will discuss the results of dendritic-cell based immunotherapy clinical trials for the treatment of malignant gliomas and explore the future strategies of DC vaccines for glioma immunotherapy.

Loss of E-cadherin promotes metastasis via multiple downstream transcriptional pathways

Loss of the epithelial adhesion molecule E-cadherin is thought to enable metastasis by disrupting intercellular contacts-an early step in metastatic dissemination. To further investigate the molecular basis of this notion, we use two methods to inhibit E-cadherin function that distinguish between E-cadherin's cell-cell adhesion and intracellular signaling functions. Whereas the disruption of cell-cell contacts alone does not enable metastasis, the loss of E-cadherin protein does, through induction of an epithelial-to-mesenchymal transition, invasiveness, and anoikis resistance. We find the E-cadherin binding partner beta-catenin to be necessary, but not sufficient, for induction of these phenotypes. In addition, gene expression analysis shows that E-cadherin loss results in the induction of multiple transcription factors, at least one of which, Twist, is necessary for E-cadherin loss-induced metastasis. These findings indicate that E-cadherin loss in tumors contributes to metastatic dissemination by inducing wide-ranging transcriptional and functional changes.

Nicotinamide adenine dinucleotide based therapeutics

Nicotinamide adenine dinucleotide (NAD), generally considered a key component involved in redox reactions, has been found to participate in an increasingly diverse range of cellular processes, including signal transduction, DNA repair, and post-translational protein modifications. In recent years, medicinal chemists have become interested in the therapeutic potential of molecules affecting interactions of NAD with NAD-dependent enzymes. Also, enzymes involved in de novo biosynthesis, salvage pathways, and down-stream utilization of NAD have been extensively investigated and implicated in a wide variety of diseases. These studies have bolstered NAD-based therapeutics as a new avenue for the discovery and development of novel treatments for medical conditions ranging from cancer to aging. Industrial and academic groups have produced structurally diverse molecules which target NAD metabolic pathways, with some candidates advancing into clinical trials. However, further intensive structural, biological, and medical studies are needed to facilitate the design and evaluation of new generations of NAD-based therapeutics. At this time, the field of NAD-therapeutics is most likely at a stage similar to that of the early successful development of protein kinase inhibitors, where analogs of ATP (a more widely utilized metabolite than NAD) began to show selectivity against target enzymes. This review focuses on key representative opportunities for research in this area, which extends beyond the scope of this article.

Structure and 1/f noise of boron doped polymorphous silicon films

The influence of structure variation on the 1/f noise of nanometric boron doped hydrogenated polymorphous silicon (pm-Si:H) films was investigated. The films were grown by the conventional radio frequency plasma enhanced chemical vapor deposition (PECVD) method. Raman spectroscopy was used to reveal the crystalline volume fraction (X(c)) and crystal size of the pm-Si:H. The measurement of optical and structure properties was carried out with spectroscopic ellipsometry (SE) in the Tauc-Lorentz model. A Fourier transform infrared (FTIR) spectrometer was used to characterize the presence of nanostructure-sized silicon clusters in pm-Si:H film deposited on KBr substrate. The electrical properties of the films were measured using evaporated coplanar nickel as the electrode. A semiconductor system was designed to obtain the 1/f noise of pm-Si:H film as well as that of amorphous and microcrystalline silicon films. The results demonstrate that the 1/f noise of pm-Si:H is nearly as low as that of microcrystalline silicon and much lower than that of amorphous silicon. The disorder to order transition mechanism of crystallization was used to analyze the decrease of noise compared with amorphous silicon.

Recent progress in immunotherapy for malignant glioma: treatment strategies and results from clinical trials

BACKGROUND

Despite advances in surgical and adjuvant radiation therapy and chemotherapy strategies, malignant gliomas continue to be associated with poor prognoses.

METHODS

We review immune-mediated treatment approaches for malignant glioma and the relevance of recent clinical trials and their outcomes. We specifically address the increasing evidence implicating the role of cytotoxic T cells in ensuring adequate immune-mediated clearance of neoplastic cells and the need for the optimization of therapies that can elicit and support such antitumor T-cell activity.

RESULTS

The poor outcome of this disease has spurred the search for novel experimental therapies that can address and overcome the root biological phenomena associated with the lethality of this disease. The use of immunotherapy to bolster the otherwise impaired antitumor immune responses in glioma patients has received increasing attention.

CONCLUSIONS

An effective treatment paradigm for malignant gliomas may eventually require a multifaceted approach combining two or more different immunotherapeutic strategies. Such scenarios may involve the use of local cytokine gene therapy to enhance glioma-cell immunogenicity in conjunction with dendritic cell-based active vaccination to stimulate systemic tumoricidal T-cell immunity. Given the heterogeneity of this disease process and the potential risk of immunoediting out a selected, treatment-refractory tumor cell population, the concurrent use of multiple modalities that target disparate tumor characteristics may be of greatest therapeutic relevance.

Spheres isolated from 9L gliosarcoma rat cell line possess chemoresistant and aggressive cancer stem-like cells

The rat 9L gliosarcoma is a widely used syngeneic rat brain tumor model that closely simulates glioblastoma multiforme when implanted in vivo. In this study, we sought to isolate and characterize a subgroup of cancer stem-like cells (CSLCs) from the 9L gliosarcoma cell line, which may represent the tumor-initiating subpopulation of cells. We demonstrate that these CSLCs form clonal-derived spheres in media devoid of serum supplemented with the mitogens epidermal growth factor and basic fibroblast growth factor, express the NSC markers Nestin and Sox2, self-renew, and differentiate into neuron-like and glial cells in vitro. More importantly, these cells can propagate and recapitulate tumors when implanted into the brain of syngeneic Fisher rats, and they display a more aggressive course compared with 9L gliosarcoma cells grown in monolayer cultures devoid of mitogens. Furthermore, we compare the chemosensitivity and proliferation rate of 9L gliosarcoma cells grown as a monolayer to those of cells grown as floating spheres and show that the sphere-generated cells have a lower proliferation rate, are more chemoresistant, and express several antiapoptosis and drug-related genes, which may prove to have important clinical implications. Disclosure of potential conflicts of interest is found at the end of this article.

Manipulation of proliferation and differentiation of human bone marrow-derived neural stem cells in vitro and in vivo

Recent evidence has demonstrated that neural stem cells (NSC) can be expanded from a variety of sources, including embryos, fetuses, and adult bone marrow and brain tissue. We have previously reported the generation of adult rat bone marrow-derived cellular spheres that are morphologically and phenotypically similar to neurospheres derived from brain NSC. Here we show that adult human bone marrow-derived neural stem cells (HBM-NSC) are capable of generating spheres that are similar to brain neural-derived neurospheres. Additionally, we sought to promote proliferation and differentiation of HBM-NSC through transduction with nonreplicative recombinant adenovirus encoding the cDNA sequence for Gli, rADV-Gli-1; sonic hedgehog, rADV-Shh; or Nurr1, rADV-Nurr1. Immunocytochemistry and RT-PCR analysis showed that HBM-NSC could be efficiently expanded and differentiated in vitro and that HBM-NSC transduced with rADV-Gli-1 or rADV-Shh dramatically increased NSC time-related proliferation; however, Nurr1 had no effect on proliferation. We also transplanted HBM-NSC into chicken embryos to examine their potential function in vivo. We found that transduction of HBM-NSC with rADV-Gli-1 or rADV-Shh and subsequent transplantation into chicken embryos increased HBM-NSC proliferation, whereas rADV-Nurr1 promoted migration and differentiation in vivo. Our findings suggest that HBM-NSC can be efficiently expanded and differentiated in vitro and in vivo by overexpressing Gli-1, Shh or Nurr1.

Networking possibilities for waste recycling in Miyagi prefecture, Japan

Successful case studies for waste recycling in Japan have not been evaluated. The evaluation of economic efficiency and environmental effects were lacking at the time the actual network was established. A waste/resource input/output (I/O) coincidence retrieval system called ZENESYS was developed to examine the usefulness of a waste-exchange network in a nonmanufacturing district. We analyzed data from the Miyagi prefecture, a region without heavy industry. The data were collected from 77 companies using a questionnaire and interviews. A total of 33 possible waste exchange links arose after analysis using ZENESYS. However, these were frail networks that relied heavily on the construction industry. Two waste recycling technologies were selected from the ZENESYS database: reclaiming fuel from waste plastic and making construction materials from bottom ash. Evaluation of the environmental effects and economics of these two technologies showed they were both suitable for the environment, but no profit was made from reclaiming fuel from waste plastics. We concluded that in an area with no heavy industry, it may be difficult to adopt recycling technologies that have high environmental and economic performance. Materials are difficult to circulate among manufacturing industries even if a waste-exchange network exists, and resources are consumed during transportation and recycling.

Analysis of gene expression and chemoresistance of CD133+ cancer stem cells in glioblastoma

BACKGROUND

Recently, a small population of cancer stem cells in adult and pediatric brain tumors has been identified. Some evidence has suggested that CD133 is a marker for a subset of leukemia and glioblastoma cancer stem cells. Especially, CD133 positive cells isolated from human glioblastoma may initiate tumors and represent novel targets for therapeutics. The gene expression and the drug resistance property of CD133 positive cancer stem cells, however, are still unknown.

RESULTS

In this study, by FACS analysis we determined the percentage of CD133 positive cells in three primary cultured cell lines established from glioblastoma patients 10.2%, 69.7% and 27.5%, respectively. We also determined the average mRNA levels of markers associated with neural precursors. For example, CD90, CD44, CXCR4, Nestin, Msi1 and MELK mRNA on CD133 positive cells increased to 15.6, 5.7, 337.8, 21.4, 84 and 1351 times, respectively, compared to autologous CD133 negative cells derived from cell line No. 66. Additionally, CD133 positive cells express higher levels of BCRP1 and MGMT mRNA, as well as higher mRNA levels of genes that inhibit apoptosis. Furthermore, CD133 positive cells were significantly resistant to chemotherapeutic agents including temozolomide, carboplatin, paclitaxel (Taxol) and etoposide (VP16) compared to autologous CD133 negative cells. Finally, CD133 expression was significantly higher in recurrent GBM tissue obtained from five patients as compared to their respective newly diagnosed tumors.

CONCLUSION

Our study for the first time provided evidence that CD133 positive cancer stem cells display strong capability on tumor's resistance to chemotherapy. This resistance is probably contributed by the CD133 positive cell with higher expression of on BCRP1 and MGMT, as well as the anti-apoptosis protein and inhibitors of apoptosis protein families. Future treatment should target this small population of CD133 positive cancer stem cells in tumors to improve the survival of brain tumor patients.

Immunomodulatory neural stem cells for brain tumour therapy

Advances in the understanding of stem cells have enabled the development of novel therapies for brain tumours. Neural stem cells (NSCs) possess the ability to migrate throughout the CNS. By exploiting the tropism of NSCs to various neural pathologies (e.g., glioma, degeneration, stroke and so on) and the delivery of various immunomodulatory cytokines, new treatments for brain tumours have been investigated. These new strategies offer significantly more specificity than existing treatment regimens, such as surgery, radiation and chemotherapy. As methods in isolating and culturing NSCs are better understood, clinical applications of this therapeutic strategy may inevitably emerge. Here, the preclinical advances and the results supporting the effectiveness of stem cell therapies are reviewed. In addition, the obstacles to clinical development and methods to circumvent these caveats are discussed.

Induction of potent antitumor immunity by intratumoral injection of interleukin 23-transduced dendritic cells

Dendritic cells (DCs) are potent antigen-presenting cells that play a critical role in priming immune responses to tumor. Interleukin (IL)-23 can act directly on DC to promote immunogenic presentation of tumor peptide in vitro. Here, we evaluated the combination of bone marrow-derived DC and IL-23 on the induction of antitumor immunity in a mouse intracranial glioma model. DCs can be transduced by an adenoviral vector coding single-chain mouse IL-23 to express high levels of bioactive IL-23. Intratumoral implantation of IL-23-expressing DCs produced a protective effect on intracranial tumor-bearing mice. The mice consequently gained systemic immunity against the same tumor rechallenge. The protective effect of IL-23-expressing DCs was comparable with or even better than that of IL-12-expressing DCs. IL-23-transduced DC (DC-IL-23) treatment resulted in robust intratumoral CD8(+) and CD4(+) T-cell infiltration and induced a specific TH1-type response to the tumor in regional lymph nodes and spleen at levels greater than those of nontransduced DCs. Moreover, splenocytes from animals treated with DC-IL-23 showed heightened levels of specific CTL activity. In vivo lymphocyte depletion experiments showed that the antitumor immunity induced by DC-IL-23 was mainly dependent on CD8(+) T cells and that CD4(+) T cells and natural killer cells were also involved. In summary, i.t. injection of DC-IL-23 resulted in significant and effective systemic antitumor immunity in intracranial tumor-bearing mice. These findings suggest a new approach to induce potent tumor-specific immunity to intracranial tumors. This approach may have therapeutic potential for treating human glioma.

Sensitization of malignant glioma to chemotherapy through dendritic cell vaccination

Drug resistance represents a major cause of chemotherapy failure in patients with cancer. The characterization of the molecular pathways involved in drug resistance has provided new targets to circumvent or reverse chemotherapy resistance. Many of these target proteins are often overexpressed in human glioma and have been identified as tumor antigens, which implicate the development of immunotherapy as a therapeutic strategy. Dendritic cells (DCs) are the most potent antigen-presenting cells of the immune system and have been demonstrated to stimulate antibody and cell-mediated immune responses against tumor-associated antigens. Ex vivo-generated and tumor antigen-loaded DCs have been successfully introduced to clinical vaccination protocols, which have proven to be feasible and effective in some glioma patients. Most importantly, immunotherapy followed by chemotherapy could significantly increase 2-year survival in malignant glioma patients, which obviously demonstrates that DC vaccination could increase the sensitivity of tumor cells to chemotherapy. This review focuses on recent advances in the identification of tumor-associated antigen in glioma, as well as novel insights into their biological function related to drug resistance. These insights may provide the rationale for a novel strategy of a DC cancer vaccine that sensitizes tumor cells to chemotherapy. In addition, the current research status and the future direction of a DC-based vaccine to treat glioma in animal models and clinical trials will also be discussed.

Interleukin-23-expressing bone marrow-derived neural stem-like cells exhibit antitumor activity against intracranial glioma

Neural progenitor-like cells have been isolated from bone marrow and the cells have the ability of tracking intracranial tumor. However, the capacity of the cells to deliver molecules for activating immune response against intracranial tumor and the identity of cellular and molecular factors that are involved in such immune responses have yet to be elucidated. Here, we isolated neural stem-like cells from the bone marrow of adult mice. The isolated cells were capable of producing progenies of three lineages, neurons, astrocytes, and oligodendrocytes, in vitro and tracking glioma in vivo. By genetically manipulating bone marrow-derived neural stem-like cells (BM-NSC) to express a recently discovered cytokine, interleukin (IL)-23, the cells showed protective effects in intracranial tumor-bearing C57BL/6 mice. Depletion of subpopulation lymphocytes showed that CD8(+) T cells were critical for the antitumor immunity of IL-23-expressing BM-NSCs and that CD4(+) T cells and natural killer (NK) cells participated in the activity. Furthermore, the IL-23-expressing BM-NSC-treated survivors were resistant to the same tumor rechallenge associated with enhanced IFN-gamma, but not IL-17, expression in the brain tissue. Taken together, these data suggest that IL-23-expressing BM-NSCs can effectively induce antitumor immunity against intracranial gliomas. CD8(+) T cells are critical for such antitumor activity; in addition, CD4(+) T cells and NK cells are also involved.

Brain tumor stem cells: new targets for clinical treatments?

✓ The observation of similarities between the self-renewal mechanisms of stem cells and cancer cells has led to the new concept of the cancer stem cell. In cases of leukemia, multiple myeloma, and breast cancer, cells with a high self-renewal potential have been identified. Furthermore, investigators have shown these cells' ability to drive the formation and growth of the tumor. Brain tumors have also been reported to possess a subpopulation of cancer stemlike cells that have the ability to proliferate, self-renew, and be multipotent. When grafted into mice, these cells are also able to generate a tumor that recapitulates that of the patient from whom the cells were derived. The identification and characterization of this new category of cells call for new therapies capable of selectively targeting and killing these multifaceted cells.

Neural progenitors populate the cerebrospinal fluid of preterm patients with hydrocephalus

OBJECTIVES

To evaluate cerebrospinal fluid (CSF) of preterm patients with hydrocephalus for neural progenitors.

STUDY DESIGN

This report describes a prospective study of CSF obtained from preterm infants, either with progressive posthemorrhagic hydrocephalus (PPHH) or without known intercranial pathology. Cells recovered by centrifugation were analyzed by reverse transcriptase-polymerase chain reaction or by immunocytometry. Alternatively, cells were cultured by using methods permissive to neural progenitor growth and analyzed by immunocytochemistry and Western blotting.

RESULTS

Human CSF cells were obtained from 20 preterm infants at approximately 27 weeks estimated gestational age (15 infants with PPHH, 5 control infants). The number of these cells removed over time from patients with PPHH were substantial, based on our calculations. Cells recovered from patients with PPHH transcribe markers for neural progenitors, all the mature cells types of the central nervous system, and a large battery of chondroitin sulfate proteoglycan genes, including the entire aggrecan/lectican family. These cells proliferated in culture, and precursor markers were detected by Western blotting, immunocytochemistry, and cytometry. Cells could not be cultured from control patients.

CONCLUSIONS

Neural progenitor accumulation in CSF could confound the clinical interpretation of CSF cell counts in hydrocephalus and may play as yet undetermined roles in the biology of injury after hydrocephalus. These findings suggest the potential for neural stem cell propagation from CSF.

Mahaley Clinical Research Award: chemosensitization of glioma through dendritic cell vaccination

A major reason chemotherapy fails in cancer treatment is drug resistance. New targets against chemotherapy resistance have been developed with the identification of molecular pathways in drug resistance. These targets are proteins that are highly expressed in human gliomas and are known to be tumor antigens. The immune system produces specialized white blood cells called dendritic cells (DCs). DCs are the most potent antigen-presenting cell of the immune system. DCs have demonstrated the ability to stimulate antibodies and cell-mediated immune responses against tumor antigens. Immunotherapy has emerged as a novel treatment strategy for gliomas with tumor antigens serving as the driving force. Clinical immunotherapy trials for glioma patients using vaccinations made of tumor antigens combined with dendritic cells ex vivo have shown promising results. DC vaccinations may increase sensitivity to chemotherapy, as demonstrated by a significant increase in 2-year survival rates in patients with malignant gliomas who received chemotherapy after immunotherapy (51). The use of DC vaccinations to increase sensitivity of tumor cells to chemotherapy can be rationalized as a novel strategy. Hence, this review will focus on the recent advances in the identification of tumor-associated antigens in gliomas, as well as their biological function related to drug resistance. The current research status and the future direction of DC vaccines to treat glioma in animal models and clinical trials will also be discussed.