The intermediate filament (nanofilament) protein nestin is a marker of neural stem cells, but its role in neurogenesis, including adult neurogenesis, remains unclear. Here, we investigated the role of nestin in neurogenesis in adult nestin-deficient (Nes–/–) mice. We found that the proliferation of Nes–/– neural stem cells was not altered, but neurogenesis in the hippocampal dentate gyrus of Nes–/– mice was increased. Surprisingly, the proneurogenic effect of nestin deficiency was mediated by its function in the astrocyte niche. Through its role in Notch signaling from astrocytes to neural stem cells, nestin negatively regulates neuronal differentiation and survival; however, its expression in neural stem cells is not required for normal neurogenesis. In behavioral studies, nestin deficiency in mice did not affect associative learning but was associated with impaired long-term memory.

Heparin-binding epidermal growth factor-like growth factor (HB-EGF), a vascular-derived trophic factor, belongs to the epidermal growth factor (EGF) family of neuroprotective, hypoxia-inducible proteins released by astrocytes in CNS injuries. It was suggested that HB-EGF can replace fetal calf serum (FCS) in astrocyte cultures. We previously demonstrated that in contrast to standard 2D cell culture systems, Bioactive3D culture system, when used with FCS, minimizes the baseline activation of astrocytes and preserves their complex morphology. Here, we show that HB-EGF induced EGF receptor (EGFR) activation by Y1068 phosphorylation, Mapk/Erk pathway activation, and led to an increase in cell proliferation, more prominent in Bioactive3D than in 2D cultures. HB-EGF changed morphology of 2D and Bioactive3D cultured astrocytes toward a radial glia-like phenotype and induced the expression of intermediate filament and progenitor cell marker protein nestin. Glial fibrillary acidic protein (GFAP) and vimentin protein expression was unaffected. RT-qPCR analysis demonstrated that HB-EGF affected the expression of Notch signaling pathway genes, implying a role for the Notch signaling in HB-EGFmediated astrocyte response. HB-EGF can be used as a FCS replacement for astrocyte expansion and in vitro experimentation both in 2D and Bioactive3D culture systems; however, caution should be exercised since it appears to induce partial de-differentiation of astrocytes.

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Background:Acute myeloid leukemia (AML) is the second most common form of leukemia and the most frequent cause of leukemia-related deaths in the US. While complete response (CR) rates can be as high as 80% in patients (pts) undergoing initial induction chemotherapy, the majority of pts relapse. Pts who relapse or who fail to achieve CR after first cycle of induction therapy have a bleak prognosis. Selinexor inhibits the major nuclear transport protein exportin (XPO1), which is overexpressed in many cancers. Hematological neoplasms are particularly susceptible to inhibition of XPO1 and undergo apoptosis, while normal hematopoietic cells are largely spared. A Phase I study with selinexor monotherapy shows encouraging results in AML pts (NCT01607892). Selinexor's mechanism of action provides a novel approach and is a suitable agent for combination therapy with Ara-C and idarubicin. Methods: Pts with relapsed/refractory AML received Ara-C (100mg/m2, d1-7) and idarubicin (10mg/m2, d1, 3, 5) every 4 weeks.Two dose schedules of selinexor were administered in combination with chemotherapy: Cohort 1 received 40mg/m2 orally, twice weekly in 4 week cycles while cohort 2 received a selinexor flat dose of 60mg orally twice weekly for 3 weeks. The rationale for employing two dose levels of selinexor was to investigate differences in toxicity and efficacy and to determine the maximum tolerated dose/recommended phase II dose. The data cutoff date was July 28, 2016. Results: Forty-two pts were enrolled into the study between 09/2014 and 06/2016 in 3 German sites. Cohort 1 comprised 27 pats: 16 M, 11 F, median age 58 years (range 22-78), who had received a median of 2 prior treatment regimens (PTR) (range 1-5) including 10 pts (37%) with prior stem cell transplantation (SCT), 33% falling into the unfavourable cytogenetic risk group. Cohort 2 comprised 15 pts: 9 M, 6 F, median age 60 years (range 29-77), who had received a median of 1 PTR (range 1-2). Six patients (40%) had prior SCT and 40% falling into the unfavourable cytogenetic risk group; all 15 pts were evaluable for safety; 11 pts for efficacy (4 pts did not have a follow-up examination due to early death). Only one third of pts had late relapse (>12 months) in both cohorts. In cohort 1 all 27 pts received induction cycle 1 (IC 1) and one pt received a second induction cycle (IC 2). Two pts had consolidation therapy. For cohort 2 the values were 15, 0 and 2 respectively. The most frequent grade 3/4 toxicities attributable to selinexor for cohort 1 were vomiting (4%, for a median of 22 days), nausea (11%, for a median of 9 days) and diarrhea (52%, for a median of 6 days). For cohort 2 the respective values were vomiting (7%, one day), nausea (7%, 21 days) and diarrhea (40% median of 2 days). The median recovery time to neutrophils ≥ 0.5/nl and platelets ≥50/nl after IC 1 in pts who experienced a CR/CRi was 40 vs. 32 days and 37 vs. 29 days, for cohorts 1 and 2 respectively. One possibly drug related death occurred in cohort 1 (systemic inflammatory response syndrome) and one in cohort 2 (hemophagocytosis syndrome). In cohort 2 three cases (sepsis, pneumonia, asystole) resulted in fatal, although unrelated, outcomes. The overall response rate (ORR) for IC 1 in cohort 1 was 55.5% (22.2% CR, 33.3% CRi). 40% of these received SCT or donor lymphocyte infusions (DLIs), achieving a median relapse free survival (RFS) of 454 days and median overall survival (OS) of 465 days. Of the cohort 1 pts achieving CR/CRi after IC 1 and not being transplanted (N=9), three relapsed resulting in a median RFS of 241 days. Median OS for non-transplanted pts was 339 days. ORR in cohort 2 (N=11) was 54.5% (27.3% CR, 18.2% CRi; 9.1% morphologic leukemia-free state). Of cohort 2 pts that achieved CR/CRi after IC 1, none received SCT or DLI and no relapses had occurred as of the data cutoff date, resulting in a median RFS and OS of 96 days; the observation period is still on-going. As of the data cutoff date, 44.4% of all pts in cohort 1 (N=27) were alive with a median OS of 328 days and a median observation period of 330 days, and 90.9% of pts in cohort 2 (N=11) with a median OS and median observation period of 96 days. Conclusion: The prognosis of relapsed/refractory AML patients is remarkably poor. Our results suggest that combined treatment of Ara-C, idarubicin and selinexor might be an effective and tolerable treatment option and serve as a bridge to transplant. The lower selinexor dose shows better tolerability and should be further explored in this setting. Disclosures Fiedler: Gilead: Other: Travel reimbursement, Gilead; Ariad/Incyte: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees, Other: Travel reimbursement, Amgen, Patents & Royalties: Amgen, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; Koltan: Research Funding; Teva: Other: Travel reimbursement Teva. Heuser:Pfizer: Research Funding; Karyopharm Therapeutics Inc: Research Funding; Bayer Pharma AG: Research Funding; Celgene: Honoraria; Novartis: Consultancy, Research Funding; Tetralogic: Research Funding; BerGenBio: Research Funding. Bokemeyer:Karyopharm: Research Funding.

Brain tumors are heterogeneous with respect to genetic and histological properties of cells within the tumor tissue. To study subpopulations of cells, we developed a protocol for obtaining viable single cells from freshly isolated human brain tissue for single cell gene expression profiling. We evaluated this technique for characterization of cell populations within brain tumor and tumor penumbra. Fresh tumor tissue was obtained from one astrocytoma grade IV and one oligodendroglioma grade III tumor as well as the tumor penumbra of the latter tumor. The tissue was dissociated into individual cells and the expression of 36 genes was assessed by reverse transcription quantitative PCR followed by data analysis. We show that tumor cells from both the astrocytoma grade IV and oligodendroglioma grade III tumor constituted cell subpopulations defined by their gene expression profiles. Some cells from the oligodendroglioma grade III tumor proper shared molecular characteristics with the cells from the penumbra of the same tumor suggesting that a subpopulation of cells within the oligodendroglioma grade III tumor consisted of normal brain cells. We conclude that subpopulations of tumor cells can be identified by using single cell gene expression profiling.