Preclinical Evaluation of Sodium Selenite in Mice: Toxicological and Tumor Regression Studies after Striatum Implantation of Human Glioblastoma Stem Cells.

Glioblastoma (GBM) is the most aggressive malignant glioma, with a very poor prognosis; as such, efforts to explore new treatments and GBM's etiology are a priority. We previously described human GBM cells (R2J-GS) as exhibiting the properties of cancer stem cells (growing in serum-free medium and proliferating into nude mice when orthotopically grafted). Sodium selenite (SS)-an in vitro attractive agent for cancer therapy against GBM-was evaluated in R2J-GS cells. To go further, we launched a preclinical study: SS was given orally, in an escalation-dose study (2.25 to 10.125 mg/kg/day, 5 days on, 2 days off, and 5 days on), to evaluate (1) the absorption of selenium in plasma and organs (brain, kidney, liver, and lung) and (2) the SS toxicity. A 6.75 mg/kg SS dose was chosen to perform a tumor regression assay, followed by MRI, in R2J-GS cells orthotopically implanted in nude mice, as this dose was nontoxic and increased brain selenium concentration. A group receiving TMZ (5 mg/kg) was led in parallel. Although not reaching statistical significance, the group of mice treated with SS showed a slower tumor growth vs. the control group (p = 0.08). No difference was observed between the TMZ and control groups. We provide new insights of the mechanisms of SS and its possible use in chemotherapy.

Rapid reprogramming of tumour cells into cancer stem cells on double-network hydrogels.

Cancer recurrence can arise owing to rare circulating cancer stem cells (CSCs) that are resistant to chemotherapies and radiotherapies. Here, we show that a double-network hydrogel can rapidly reprogramme differentiated cancer cells into CSCs. Spheroids expressing elevated levels of the stemness genes Sox2, Oct3/4 and Nanog formed within 24 h of seeding the gel with cells from any of six human cancer cell lines or with brain cancer cells resected from patients with glioblastoma. Human brain cancer cells cultured on the double-network hydrogel and intracranially injected in immunodeficient mice led to higher tumorigenicity than brain cancer cells cultured on single-network gels. We also show that the double-network gel induced the phosphorylation of tyrosine kinases, that gel-induced CSCs from primary brain cancer cells were eradicated by an inhibitor of the platelet-derived growth factor receptor, and that calcium channel receptors and the protein osteopontin were essential for the regulation of gel-mediated induction of stemness in brain cancer cells.

mTOR Signaling Combined with Cancer Stem Cell Markers as a Survival Predictor in Stage II Colorectal Cancer.

PURPOSE: Wnt and mammalian target of rapamycin (mTOR) are major molecular signaling pathways associated with the development and progression of tumor, as well as the maintenance and proliferation of cancer stem cells (CSCs), in colorectal cancer (CRC). Identifying patients at risk of poor prognosis is important to determining whether to add adjuvant treatment in stage II CRC and thus improve survival. In the present study, we evaluated the prognostic value of Wnt, mTOR, and CSC markers as survival predictors in stage II CRC. MATERIALS AND METHODS: We identified 148 cases of stage II CRC and acquired their tumor tissue. Tissue microarrays for immunohistochemical staining were constructed, and the expressions of CD166, CD44, EphB2, ß-catenin, pS6 were evaluated using immunohistochemical staining. RESULTS: The expressions of CD166 (p=0.045) and pS6 (p=0.045) and co-expression of pS6/CD166 (p=0.005), pS6/CD44 (p=0.042), and pS6/CD44/CD166 (p=0.013) were negatively correlated with cancer-specific survival. Cox proportional hazard analysis showed the combination of CD166/pS6 [hazard ratio, 9.42; 95% confidence interval, 2.36-37.59; p=0.002] to be the most significant predictor related with decreased cancer-specific survival. In addition, co-expression of CD44/CD166 (p=0.017), CD166/ß-catenin (p=0.036), CD44/ß-catenin (p=0.001), and CD44/CD166/ß-catenin (p=0.001) were significant factors associated with liver metastasis. CONCLUSION: Specific combinations of CSC markers and ß-catenin/mTOR signaling could be a significant predictor of poor survival in stage II CRC.

Cell-based and antibody-mediated immunotherapies directed against leukemic stem cells in acute myeloid leukemia: Perspectives and open issues.

Despite new insights in molecular features of leukemic cells and the availability of novel treatment approaches and drugs, acute myeloid leukemia (AML) remains a major clinical challenge. In fact, many patients with AML relapse after standard therapy and eventually die from progressive disease. The basic concept of leukemic stem cells (LSC) has been coined with the goal to decipher clonal architectures in various leukemia-models and to develop curative drug therapies by eliminating LSC. Indeed, during the past few years, various immunotherapies have been tested in AML, and several of these therapies follow the strategy to eliminate relevant leukemic subclones by introducing LSC-targeting antibodies or LSC-targeting immune cells. These therapies include, among others, new generations of LSC-eliminating antibody-constructs, checkpoint-targeting antibodies, bi-specific antibodies, and CAR-T or CAR-NK cell-based strategies. However, responses are often limited and/or transient which may be due to LSC resistance. Indeed, AML LSC exhibit multiple forms of resistance against various drugs and immunotherapies. An additional problems are treatment-induced myelotoxicity and other side effects. The current article provides a short overview of immunological targets expressed on LSC in AML. Moreover, cell-based therapies and immunotherapies tested in AML are discussed. Finally, the article provides an overview about LSC resistance and strategies to overcome resistance.

GSK­3 inhibitor CHIR99021 enriches glioma stem­like cells.

Glioblastoma (GBM) is the most prevalent and lethal primary intrinsic brain cancer. The disease is essentially incurable, with glioblastomas characterized by resistance to both chemotherapy and radiotherapy, as well as by rapid tumor progression, all of which are mainly ascribed to glioma stem­like cells (GSLCs). In the present study, an improved model that is more similar to clinical GBM was constructed. Twenty clinical glioma samples were collected to obtain primary low­grade tumor cells. The cells were either maintained in serum­free medium as primary glioma­based cells (PGBCs) or cultured in the same medium with CHIR99021 as GSLCs. Then, the molecular and ultrastructural differences between the two cell groups were determined. Furthermore, the proliferation and migration of the GSLCs were examined and the potential mechanisms were investigated. Finally, temozolomide resistance in vitro and in the mouse model was assessed to study the properties of the induced GSLCs. The primary low­grade tumor cells extracted from surgical samples were enriched with GSLC properties, with high expression levels of CD133 and Nestin in 100 nM CHIR99021. The GSLCs exhibited high proliferation and migration. Furthermore, the expression of the PI3K/AKT signaling pathway and that of related genes and proteins were significantly enhanced by CHIR99021. The animal study also revealed high levels of STAT3, mTOR, NF­κB, and VEGF in the GSLC­transplanted mice. CHIR99021 could stably enhance GSLC properties in patient­derived glioma samples. It may provide a useful model for further study, helping to understand the pathogenesis of therapeutic resistance and to screen drug candidates.

Patient­derived orthotopic xenograft glioma models fail to replicate the magnetic resonance imaging features of the original patient tumor.

Patient­derived orthotopic glioma xenograft models are important platforms used for pre­clinical research of glioma. In the present study, the diagnostic ability of magnetic resonance imaging (MRI) was examined with regard to the identification of biomarkers obtained from patient­derived glioma xenografts and human tumors. Conventional MRI, diffusion weighted imaging and dynamic contrast­enhanced (DCE)­MRI were used to analyze seven pairs of high grade gliomas with their corresponding xenografts obtained from non­obese diabetic­severe­combined immunodeficiency nude mice. Tumor samples were collected for transcriptome sequencing and histopathological staining, and differentially expressed genes were screened between the original tumors and the corresponding xenografts. Gene Ontology (GO) analysis was performed to predict the functions of these genes. In 6 cases of xenografts with diffuse growth, the degree of enhancement was significantly lower compared with the original tumors. Histopathological staining indicated that the microvascular area and microvascular diameter of the xenografts were significantly lower compared with the original tumors (P=0.009 and P=0.007, respectively). In one case, there was evidence of nodular tumor growth in the mouse. Both MRI and histopathological staining showed a clear demarcation between the transplanted tumors and the normal brain tissues. The relative apparent diffusion coefficient values of the 7 cases examined were significantly higher compared with the corresponding original tumors (P=0.001) and transfer coefficient values derived from DCE­MRI of the tumor area was significantly lower compared with the original tumors (P=0.016). GO analysis indicated that the expression levels of extracellular matrix­associated genes, angiogenesis­associated genes and immune function­associated genes in the original tumors were higher compared with the corresponding xenografts. In conclusion, the data demonstrated that the MRI features of patient­derived xenograft glioma models in mice were different compared with those of the original patient tumors. Differential gene expression may underlie the differences noted in the MRI features between original tumors and corresponding xenografts. The results of the present study highlight the precautions that should be taken when extrapolating data from patient­derived xenograft studies, and their applicability to humans.

Targeting Interleukin(IL)-30/IL-27p28 signaling in cancer stem-like cells and host environment synergistically inhibits prostate cancer growth and improves survival.

BACKGROUND: Interleukin(IL)-30/IL-27p28 production by Prostate Cancer (PC) Stem-Like Cells (SLCs) has proven, in murine models, to be critical to tumor onset and progression. In PC patients, IL-30 expression by leukocytes infiltrating PC and draining lymph nodes correlates with advanced disease grade and stage. Here, we set out to dissect the role of host immune cell-derived IL-30 in PC growth and patient outcome. METHODS: PC-SLCs were implanted in wild type (WT) and IL-30 conditional knockout (IL-30KO) mice. Histopathological and cytofluorimetric analyses of murine tumors and lymphoid tissues prompted analyses of patients' PC samples and follow-ups. RESULTS: Implantation of PC-SLCs in IL-30KO mice, gave rise to slow growing tumors characterized by apoptotic events associated with CD4+T lymphocyte infiltrates and lack of CD4+Foxp3+ T regulatory cells (Tregs). IL-30 knockdown in PC-SLCs reduced cancer cell proliferation, vascularization and intra-tumoral Indoleamine 2,3-Dioxygenase (IDO)+CD11b+Gr-1+ myeloid-derived cells (MDCs) and led to a significant delay in tumor growth and increase in survival. IL-30-silenced tumors developed in IL-30KO mice, IL-30-/-tumors, lacked vascular supply and displayed frequent apoptotic cancer cells entrapped by perforin+TRAIL+CD3+Tlymphocytes, most of which had a CD4+T phenotype, whereas IL-10+TGFß+Foxp3+Tregs were lacking. IL-30 silencing in PC-SLCs prevented lung metastasis in 73% of tumor-bearing WT mice and up to 80% in tumor-bearing IL-30KO mice. In patients with high-grade and locally advanced PC, those with IL-30-/-tumors, showed distinct intra-tumoral cytotoxic granule-associated RNA binding protein (TIA-1)+CD4+Tlymphocyte infiltrate, rare Foxp3+Tregs and a lower biochemical recurrence rate compared to patients with IL-30+/+tumors in which IL-30 is expressed in both tumor cells and infiltrating leukocytes. CONCLUSION: The lack of host leukocyte-derived IL-30 inhibits Tregs expansion, promotes intra-tumoral infiltration of CD4+T lymphocytes and cancer cell apoptosis. Concomitant lack of MDC influx, obtained by IL-30 silencing in PC-SLCs, boosts cytotoxic T lymphocyte activation and cancer cell apoptosis resulting in a synergistic tumor suppression with the prospective benefit of better survival for patients with advanced disease.

Transplantation of human meningioma stem cells loaded on a self-assembling peptide nanoscaffold containing IKVAV improves traumatic brain injury in rats.

Traumatic brain injury (TBI) can result in permanent brain function impairment due to the poor regenerative ability of neural tissue. Tissue engineering has appeared as a promising approach to promote nerve regeneration and to ameliorate brain damage. The present study was designed to investigate the effect of transplantation of the human meningioma stem-like cells (hMgSCs) seeded in a promising three-dimensional scaffold (RADA4GGSIKVAV; R-GSIK) on the functional recovery of the brain and neuroinflammatory responses following TBI in rats. After induction of TBI, hMgSCs seeded in R-GSIK was transplanted within the injury site and its effect was compared to several control groups. Application of hMgSCs with R-GSIK improved functional recovery after TBI. A significant higher number of hMgSCs was observed in the brain when transplanted with R-GSIK scaffold compared to the control groups. Application of hMgSCs seeded in R-GSIK significantly decreased the lesion volume, reactive gliosis, and apoptosis at the injury site. Furthermore, treatment with hMgSCs seeded in R-GSIK significantly inhibited the expression of Toll-like receptor 4 and its downstream signaling molecules, including interleukin-1ß and tumor necrosis factor. These data revealed the potential for hMgSCs seeded in R-GSIK to improve the functional recovery of the brain after TBI; possibly via amelioration of inflammatory responses. STATEMENT OF SIGNIFICANCE: Tissue engineered scaffolds that mimic the natural extracellular matrix of the brain may modulate stem cell fate and contribute to tissue repair following traumatic brain injury (TBI). Among several scaffolds, self-assembly peptide nanofiber scaffolds markedly promotes cellular behaviors, including cell survival and differentiation. We developed a novel three-dimensional scaffold (RADA16GGSIKVAV; R-GSIK). Transplantation of the human meningioma stem-like cells seeded in R-GSIK in an animal model of TBI significantly improved functional recovery of the brain, possibly via enhancement of stem cell survival as well as reduction of the lesion volume, inflammatory process, and reactive gliosis at the injury site. R-GSIK is a suitable microenvironment for human stem cells and could be a potential biomaterial for the reconstruction of the injured brain after TBI.

A robust culture method for maintaining tumorigenic cancer stem cells in the hepatocellular carcinoma cell line Li-7.

Cancer tissues contain small populations of highly tumorigenic cells termed cancer stem cells (CSCs). Immortalized cell lines containing CSCs are valuable and powerful experimental tools for research into the characteristics of these stem cells. We previously reported that the hepatocellular carcinoma cell line Li-7 includes abundant CD13+ CD166- CSCs; however, the number of these cells decreases after long-term culture as a result of differentiation to non-CSC populations. To ensure consistent and reproducible results in experiments using Li-7 cells, it is important that the CSC population is maintained stably regardless of culture duration and passage. In the present study, we found that a commercially available culture medium for maintenance of embryonic stem cells and induced pluripotent stem cells, mTeSR1, effectively prevented spontaneous differentiation by CD13+ CD166- cells to CD13- CD166+ cells and therefore maintained the CSC population in Li-7 cell cultures. CD13+ CD166- CSCs maintained using this culture medium retained high tumorigenicity after transplantation into mice; they also showed the ability to differentiate in vitro into non-CSC populations in RPMI-1640 with 10% FBS medium. We analyzed gene expression profiles of CSC and non-CSC populations in Li-7 cultures using an RNA sequencing method. Genes such as FGFR, NOTCH1, and JAG1, that are associated with tumorigenicity and stemness, were upregulated in the CSC population. Our results suggest that CSCs can be maintained in immortalized cancer cell lines cultured over an extended period using a medium developed for culture of embryonic/induced pluripotent stem cells.

Updates in pancreatic cancer: Modest gains and hopeful targets.

Pancreatic cancer is the twelfth most common cancer in the United States, representing 3.2% of all new cancer cases. While composing a small percentage of cancer diagnoses, pancreatic cancer is amongst the most lethal carcinomas, with an overall 5-year survival of 8.2% and incidence rates almost equivocal to death rates. By the time of diagnosis, a majority of patients will present with advanced stage disease. For patients with resectable disease, the estimated overall survival (OS) remains low at 20% as most will develop metastatic disease within 5 years. The lethality of this cancer is attributed to several factors including delayed presentation, lack of effective screening, and complex tumor biology and genetics. Data also suggest that even upon early presentation, pancreatic cancer is a systemic disease with micrometastasis present in the early stages. Traditional cytotoxic therapies have not been clinically impactful in pancreatic cancer, especially in advanced stages, and very little headway has been made in the development of new targeted therapies. As such, this review will discuss current advances in standard of care treatments and novel drug targets being researched.

Cancer Stem Cell Vaccination With PD-L1 and CTLA-4 Blockades Enhances the Eradication of Melanoma Stem Cells in a Mouse Tumor Model.

Immune checkpoint inhibitors and monoclonal antibodies reinvigorate cancer immunotherapy. However, these immunotherapies only benefit a subset of patients. We previously reported that ALDH tumor cells were highly enriched for cancer stem cells (CSCs), and ALDH CSC lysate-pulsed dendritic cell (CSC-DC) vaccine was shown to induce CSC-specific cytotoxic T lymphocytes. In this study, we investigated the CSC targeting effect of the CSC-DC vaccine combined with a dual blockade of programmed death-ligand 1 and cytotoxic T-lymphocyte-associated protein (CTLA-4) in B16-F10 murine melanoma tumor model. Our data showed that animals treated with the dual blockade of programmed death-ligand 1 and CTLA-4 and CSC-DC vaccine conferred significantly more tumor regression than the CSC-DC vaccine alone. Importantly, the triple combination treatment dramatically eliminated ALDH CSCs in vivo. We observed that CSC-DC vaccine in combination with anti-PD-L1 and anti-CTLA-4 administration resulted in ∼1.7-fold fewer PD-1CD8 T cells and ∼2.5-fold fewer CTLA-4CD8 T cells than the populations observed following the CSC-DC vaccination alone. Moreover, significant antitumor effects and dramatically eliminated ALDH CSCs following the triple combination treatment were accompanied by significantly enhanced T-cell expansion, suppressed transforming growth factor ß secretion, enhanced IFN-γ secretion, and significantly enhanced host specific CD8 T-cell response against CSCs. Collectively, these data showed that administration of a-PD-L1 and a-CTLA-4 combined with CSC-DC vaccine may represent an effective immunotherapeutic strategy for cancer patients in clinical.

Cancer stem cells as targets for DC-based immunotherapy of colorectal cancer.

The therapy of colorectal cancer (CRC) patients is often unsuccessful because of the presence of cancer stem cells (CSCs) resistant to conventional approaches. Dendritic cells (DC)-based protocols are believed to effectively supplement CRC therapy. Our study was aimed to assess how the number and properties of CSCs isolated from tumor tissue of CRC patients will affect the biological characteristics of in vitro modified DCs. Similar procedures were conducted with the using of CRC HCT116 and HT29 cell lines. We found that the detailed configuration of CSC-like markers significantly influenced the maturation and activation of DCs after stimulation with cancer cells lysates or culture supernatants. This basic stimulatory effect was enhanced by LPS that is normally present in CRC CSCs niche. The increased number of CD29+ and CD44+ CSCs presented the opposite impact on treated DCs as showed by many significant correlations. The CD133+ CSCs seemed to impair the functions of DCs. The more CD133+ CSCs in tumor sample the lower number of activated DCs evidenced after stimulation. Moreover, our results showed superiority of the spherical culture model over the adherent one since spherical HCT116 and HT29 cells presented similar influence on DCs properties as CRC patients cancer cells. We concluded that the DCs features may depend directly on the properties of CSCs affected by progression status of tumor.

Concise Review: Prostate Cancer Stem Cells: Current Understanding.

Prostate cancer (PCa) is heterogeneous, harboring phenotypically diverse cancer cell types. PCa cell heterogeneity is caused by genomic instability that leads to the clonal competition and evolution of the cancer genome and by epigenetic mechanisms that result in subclonal cellular differentiation. The process of tumor cell differentiation is initiated from a population of prostate cancer stem cells (PCSCs) that possess many phenotypic and functional properties of normal stem cells. Since the initial reports on PCSCs in 2005, there has been much effort to elucidate their biological properties, including unique metabolic characteristics. In this Review, we discuss the current methods for PCSC enrichment and analysis, the hallmarks of PCSC metabolism, and the role of PCSCs in tumor progression. Stem Cells 2018;36:1457-1474.

Reinforcing the utility of chick embryo model to in vivo evaluate engraftment of human leukemic stem cells.

BACKGROUND AND OBJECTIVE: Development of appropriate translational in vivo models is a prerequisite for personalized management of leukemic patients. Indeed, several immunodeficient mice models were developed for leukemias with main limitations due to their high cost, demanding management, and elongated assessment intervals. In this report, we aimed at evaluating the engraftment of CD34+ cells, isolated from an acute myeloid leukemia (AML) patient, in naturally immunodeficient chick embryo model. METHODS AND RESULTS: Mononuclear cells or immunomagnetic sorted CD34+ cells were injected into chick embryo chorioallantoic membrane (CAM) veins. Seven days post-injection, human CD34 transcript was detected by reverse transcription polymerase chain reaction (RT-PCR) in blood, bone marrow (BM), spleen and liver from embryos injected with human leukemic cells. Interestingly, an amplicon of the same length has been detected in both BM and spleen from PBS injected embryos, although analysis via bioinformatics tools revealed no matches in chicken; neither in transcriptome nor in genome databases. Importantly, splenomegaly and hepatic lesions were observed in some CD34+ cells injected embryos. CONCLUSION: Collectively, our data confirm the engraftment of primary human CD34+ leukemic cells in chick embryo liver, but other experiments are required to verify engraftment in BM and spleen, and to confirm the identity of a putative CD34 orthologous transcript in these two organs.

Acute myeloid leukemia xenograft success prediction: Saving time.

Xenograft assay allows functional analysis of leukemia-initiating cells of acute myeloid leukemia primary samples. However, 40% of samples derived from patients with better outcomes fail to engraft in immunodeficient mouse recipients when conventional protocols are followed. At diagnosis, the engraftment of intermediate-risk group samples cannot be anticipated. In this study, we decided to further explore the reasons for xenograft success and failure. No differences in extracellular phenotype, apoptosis, or cell cycle profile could distinguish samples that engraft (engrafter [E]) from samples that do not engraft (nonengrafter [NE]) in NSG mice. In addition, ex vivo long-term culture assay revealed, after 5 weeks, a lower content of leukemic-LTC-initiating cells in the NE samples associated with a lower expansion rate capacity. One-week co-cultures with mesenchymal or osteoblastic or endothelial cells did not influence the proliferation rate, suggesting that E and NE samples are genuinely rapidly or slowly expanding independent of external cue. Engraftment success for some NE samples was consistently observed in recipient mice analyzed 6 months later than the conventional 3-month period. Eventually we implemented a flow cytometry-based assay, which allowed us to predict, in 1 week, the fast or delayed engraftment potential of a noncharacterized acute myeloid leukemia sample. This approach will be especially useful in selecting intermediate-risk-group patient samples and restricting the experimental duration to a 3-month period and, eventually, in reducing the number of animals and the cost and effort of unnecessary xenograft failures.

Exosomes from Glioma-Associated Mesenchymal Stem Cells Increase the Tumorigenicity of Glioma Stem-like Cells via Transfer of miR-1587.

Tumor-stromal communications impact tumorigenesis in ways that are incompletely understood. Here, we show that glioma-associated human mesenchymal stem cells (GA-hMSC), a newly identified stromal component of glioblastoma, release exosomes that increase the proliferation and clonogenicity of tumor-initiating glioma stem-like cells (GSC). This event leads to a significantly greater tumor burden and decreased host survival compared with untreated GSCs in orthotopic xenografts. Analysis of the exosomal content identified miR-1587 as a mediator of the exosomal effects on GSCs, in part via downregulation of the tumor-suppressive nuclear receptor corepressor NCOR1. Our results illuminate the tumor-supporting role for GA-hMSCs by identifying GA-hMSC-derived exosomes in the intercellular transfer of specific miRNA that enhance the aggressiveness of glioblastoma. Cancer Res; 77(21); 5808-19. ©2017 AACR.

Effective tumor immunity to melanoma mediated by B16F10 cancer stem cell vaccine.

Although tumor vaccines have been considered a promising immunotherapy approach, therapeutic tumor vaccines are mostly disappointing in the clinic due to vaccine weak immunogenicity. Cancer stem cells (CSCs) may broaden the antigenic breadth and effectively induce the immune responses against autologous cancer cells. Here we report on the development of the B16F10 CD133+CD44+CSCs (B16F10 CSCs) vaccine to induce tumor immunity to melanoma in mice. Efficacy of against melanoma was evaluated by analysis of tumor growth and mouse survival. Immunogenicity was assessed by ELISA and flow cytometric assays, including serum cytokines, cytotoxic activity of NK cells and splenocytes in the immunized mice. The results showed that the B16F10 CSC vaccine resulted in tumor shrinkage and mouse lifespan extension. The cytotoxic activity and IFN-γ level were significantly increased in mice immunized with B16F10 CSC vaccine compared with the mice immunized with control vaccines. Additionally, New York esophageal squamous cell carcinoma-1, an efficient tumor associated antigen over-expressed by B16F10 CSCs, was markedly reduced in expression in melanoma tissue, suggesting decrease of CSC subpopulation due to B16F10 CSC vaccination. Collectively, the findings may represent a new powerful approach for treatment of melanoma by B16F10 CSC vaccination.

Optimization of Glioblastoma Mouse Orthotopic Xenograft Models for Translational Research.

Glioblastoma is an aggressive primary brain tumor predominantly localized to the cerebral cortex. We developed a panel of patient-derived mouse orthotopic xenografts (PDOX) for preclinical drug studies by implanting cancer stem cells (CSC) cultured from fresh surgical specimens intracranially into 8-wk-old female athymic nude mice. Here we optimize the glioblastoma PDOX model by assessing the effect of implantation location on tumor growth, survival, and histologic characteristics. To trace the distribution of intracranial injections, toluidine blue dye was injected at 4 locations with defined mediolateral, anterioposterior, and dorsoventral coordinates within the cerebral cortex. Glioblastoma CSC from 4 patients and a glioblastoma nonstem-cell line were then implanted by using the same coordinates for evaluation of tumor location, growth rate, and morphologic and histologic features. Dye injections into one of the defined locations resulted in dye dissemination throughout the ventricles, whereas tumor cell implantation at the same location resulted in a much higher percentage of small multifocal ventricular tumors than did the other 3 locations tested. Ventricular tumors were associated with a lower tumor growth rate, as measured by in vivo bioluminescence imaging, and decreased survival in 4 of 5 cell lines. In addition, tissue oxygenation, vasculature, and the expression of astrocytic markers were altered in ventricular tumors compared with nonventricular tumors. Based on this information, we identified an optimal implantation location that avoided the ventricles and favored cortical tumor growth. To assess the effects of stress from oral drug administration, mice that underwent daily gavage were compared with stress-positive and -negative control groups. Oral gavage procedures did not significantly affect the survival of the implanted mice or physiologic measurements of stress. Our findings document the importance of optimization of the implantation site for preclinical mouse models of glioblastoma.

A potent indolylquinoline alleviates growth of human lung cancer cell tumorspheres.

To fight cancer at its roots by targeting cancer stem cells is a promising approach for therapy. Previously, an indolylquinoline derivative, 3-((7-ethyl-1H-indol-3-yl)-methyl)-2-methylquinoline (EMMQ), was reported effectively inhibiting the growth of lung cancer cells through impairment of cellular mitochondria functions. To address more on drug efficiency, the study further exploited if EMMQ can impede the propagation of tumorspheres stemmed from non-small cell lung cancer cells. EMMQ inhibited proliferation of spheroids in culture. In animal models, administration of the drug attenuated the spheroid tumorigenicity. The activated apoptosis alleviated growth of xenograft tumors in immune-deficient mice as established by the enriched tumorspheres. More evidence suggested that the reduced stemness of the spheroid tumors is attributed to apoptotic death. The findings supported that EMMQ is an eligible approach to eradicate the minor but tumorigenic lung cancer tumorspheres.

A rare castration-resistant progenitor cell population is highly enriched in Pten-null prostate tumours.

Castration-resistant prostate cancer is a lethal disease. The cell type(s) that survive androgen deprivation remain poorly described, despite global efforts to understand the various mechanisms of therapy resistance. We recently identified in wild-type (WT) mouse prostates a rare population of luminal progenitor cells that we called LSCmed according to their FACS profile (Lin- /Sca-1+ /CD49fmed ). Here, we investigated the prevalence and castration resistance of LSCmed in various mouse models of prostate tumourigenesis (Pb-PRL, Ptenpc-/- , and Hi-Myc mice). LSCmed prevalence is low (∼8%, similar to WT) in Hi-Myc mice, where prostatic androgen receptor signalling is unaltered, but is significantly higher in the two other models, where androgen receptor signalling is decreased, rising up to more than 80% in Ptenpc-/- prostates. LSCmed tolerate androgen deprivation and persist or are enriched 2-3 weeks after castration. The tumour-initiating properties of LSCmed from Ptenpc-/- mice were demonstrated by regeneration of tumours in vivo. Transcriptomic analysis revealed that LSCmed represent a unique cell entity as their gene expression profile is different from luminal and basal/stem cells, but shares markers of each. Their intrinsic androgen signalling is markedly decreased, explaining why LSCmed tolerate androgen deprivation. This also illuminates why Ptenpc-/- tumours are castration-resistant since LSCmed represent the most prevalent cell type in this model. We validated CK4 as a specific marker for LSCmed on sorted cells and prostate tissues by immunostaining, allowing for the detection of LSCmed in various mouse prostate specimens. In castrated Ptenpc-/- prostates, there was significant proliferation of CK4+ cells, further demonstrating their key role in castration-resistant prostate cancer progression. Taken together, this study identifies LSCmed as a probable source of prostate cancer relapse after androgen deprivation and as a new therapeutic target for the prevention of castrate-resistant prostate cancer. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.