Cancer stem cells (CSCs) are thought to be critical for the engraftment and long-term growth of many tumors, including glioblastoma (GBM). The cells are at least partially spared by traditional chemotherapies and radiation therapies, and finding new treatments that can target CSCs may be critical for improving patient survival. It has been shown that the NOTCH signaling pathway regulates normal stem cells in the brain, and that GBMs contain stemlike cells with higher NOTCH activity. We therefore used low-passage and established GBM-derived neurosphere cultures to examine the overall requirement for NOTCH activity, and also examined the effects on tumor cells expressing stem cell markers. NOTCH blockade by c-secretase inhibitors (GSIs) reduced neurosphere growth and clonogenicity in vitro, whereas expression of an active form of NOTCH2 increased tumor growth. The putative CSC markers CD133, NESTIN, BMI1, and OLIG2 were reduced following NOTCH blockade. When equal numbers of viable cells pretreated with either vehicle (dimethyl sulfoxide) or GSI were injected subcutaneously into nude mice, the former always formed tumors, whereas the latter did not. In vivo delivery of GSI by implantation of drug-impregnated polymer beads also effectively blocked tumor growth, and significantly prolonged survival, albeit in a relatively small cohort of animals. We found that NOTCH pathway inhibition appears to deplete stem-like cancer cells through reduced proliferation and increased apoptosis associated with decreased AKT and STAT3 phosphorylation. In summary, we demonstrate that NOTCH pathway blockade depletes stem-like cells in GBMs, suggesting that GSIs may be useful as chemotherapeutic reagents to target CSCs in malignant gliomas.

The Notch signaling pathway is required in both nonneoplastic neural stem cells and embryonal brain tumors, such as medulloblastoma, which are derived from such cells.

BackgroundCross-sectional assessment of HIV incidence relies on laboratory methods to discriminate between recent and non-recent HIV infection. Because HIV diversifies over time in infected individuals, HIV diversity may serve as a biomarker for assessing HIV incidence. We used a high resolution melting (HRM) diversity assay to compare HIV diversity in adults with different stages of HIV infection. This assay provides a single numeric HRM score that reflects the level of genetic diversity of HIV in a sample from an infected individual.MethodsHIV diversity was measured in 203 adults: 20 with acute HIV infection (RNA positive, antibody negative), 116 with recent HIV infection (tested a median of 189 days after a previous negative HIV test, range 14–540 days), and 67 with non-recent HIV infection (HIV infected >2 years). HRM scores were generated for two regions in gag, one region in pol, and three regions in env.ResultsMedian HRM scores were higher in non-recent infection than in recent infection for all six regions tested. In multivariate models, higher HRM scores in three of the six regions were independently associated with non-recent HIV infection.ConclusionsThe HRM diversity assay provides a simple, scalable method for measuring HIV diversity. HRM scores, which reflect the genetic diversity in a viral population, may be useful biomarkers for evaluation of HIV incidence, particularly if multiple regions of the HIV genome are examined.

Background We evaluated use of the ARCHITECT® HIV Ag/Ab Combo assay (HIV Combo; Abbott Diagnostics; available for sale outside of the U.S. only) for detection of acute HIV infection. Methods Samples were obtained from a behavioral intervention study (EXPLORE). HIV-uninfected men who have sex with men were enrolled and tested for HIV infection every 6 months. Samples from seroconverters collected at their last seronegative visit (n=217) were tested individually using two HIV RNA assays. Samples with detectable HIV RNA were classified as acute and were tested with HIV Combo. Samples from the enrollment visit (n=83) and the time of HIV seroconversion (n=219) were tested with HIV Combo as controls. Results Twenty-one (9.7%) samples from the last seronegative visit had detectable HIV RNA and were classified as acute. HIV Combo was positive for 13 (61.9%) of the acute samples. Samples not detected by HIV Combo had viral loads of 724 to 15,130 copies/ml. Expected results were obtained for positive and negative controls tested with HIV Combo. Conclusions HIV Combo detected nearly two-thirds of acute HIV infections identified in this high-risk population by non-pooled, HIV RNA assays. HIV Combo may be useful for high-throughput screening to identify individuals with acute HIV infection.