Despite great efforts in the lab and clinic, glioblastoma multiformi (GBM) has a poor prognosis. Current therapy consists of surgery followed by radiotherapy and chemotherapy with temozolomide (TMZ). Recent studies in several laboratories have demonstrated that GBM cultures in defined medium provide a better model than classical cell lines maintained with fetal bovine serum. As a result, we have placed a series of brain tumors into culture. We used these cultures to test the hypothesis that cancer stem cells (CSC) are relatively resistant to chemotherapy, using neurosphere formation as an assay for CSCs. To our surprise, the concentrations of chemotherapy drugs required to inhibit neurosphere formation are much lower than those required to inhibit bulk cell proliferation or to induce cell death. Further study demonstrated that the inhibition of neurosphere formation is due to reversible quiescence of CSCs, which facilitates DNA repair, lessens chemotoxicity and hence, decreases the efficacy of chemotherapy. We considered strategies to enhance the effects of chemotherapy. We were drawn to a recent discovery that inhibition of Notch signaling forces quiescent fibroblasts to become senescent. Notch signaling with a gamma secretase inhibitor (GSI) enhances TMZ-induced senescence. Based on these results, we hypothesize that TMZ therapy can be enhanced by suppression of the Notch pathway. Our overall objective is to develop TMZ+GSI as a novel therapy.
Aim 1 is to determine the mechanism by which GSI enhances TMZ therapy. We predict that the GSI enhances TMZ therapy by inhibiting the Notch pathway and its downstream target, Hes1.
Aim 2 is to assess the biological responses to TMZ+GSI, including senescence. We also will determine the roles of p53 and cyclin-dependent kinase inhibitors.
Aim 3 is to optimize conditions for the TMZ+GSI treatment. We will compare several treatment schedules and carry out TMZ+GSI therapy in vivo in immunocompromised mice. These experiments will provide a sound foundation for moving this novel therapy to the clinic.

Public Health Relevance

Glioblastoma multiforme is the highest-grade brain tumor and is a tremendously difficult clinical problem. The current therapy is a combination of surgery, radiotherapy and chemotherapy with temozolomide, resulting in a 5% 5-year survival rate. We recently discovered that inhibitors of the Notch signaling pathway enhance temozolomide treatment of glioblastoma cell in culture. Our goal is to understand the underlying mechanism, identity markers for responsive glioblastomas and translate these observations to the clinic.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-BDCN-W (03))
Program Officer
Fountain, Jane W
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Massachusetts Medical School Worcester
Schools of Medicine
United States
Zip Code
Weatherbee, Jessica L; Kraus, Jean-Louis; Ross, Alonzo H (2016) ER stress in temozolomide-treated glioblastomas interferes with DNA repair and induces apoptosis. Oncotarget 7:43820-43834
Heinrich, Frank; Chakravarthy, Srinivas; Nanda, Hirsh et al. (2015) The PTEN Tumor Suppressor Forms Homodimers in Solution. Structure 23:1952-1957
Harishchandra, Rakesh K; Neumann, Brittany M; Gericke, Arne et al. (2015) Biophysical methods for the characterization of PTEN/lipid bilayer interactions. Methods 77-78:125-35
Ramirez, Yulian P; Mladek, Ann C; Phillips, Roger M et al. (2015) Evaluation of novel imidazotetrazine analogues designed to overcome temozolomide resistance and glioblastoma regrowth. Mol Cancer Ther 14:111-9
Karpel-Massler, Georg; Shu, Chang; Chau, Lily et al. (2015) Combined inhibition of Bcl-2/Bcl-xL and Usp9X/Bag3 overcomes apoptotic resistance in glioblastoma in vitro and in vivo. Oncotarget 6:14507-21
Pareja, Fresia; Macleod, David; Shu, Chang et al. (2014) PI3K and Bcl-2 inhibition primes glioblastoma cells to apoptosis through downregulation of Mcl-1 and Phospho-BAD. Mol Cancer Res 12:987-1001
Jiang, Zhiping; Redfern, Roberta E; Isler, Yasmin et al. (2014) Cholesterol stabilizes fluid phosphoinositide domains. Chem Phys Lipids 182:52-61
Ramirez, Yulian P; Weatherbee, Jessica L; Wheelhouse, Richard T et al. (2013) Glioblastoma multiforme therapy and mechanisms of resistance. Pharmaceuticals (Basel) 6:1475-506
Gericke, Arne; Leslie, Nicholas R; Lösche, Mathias et al. (2013) PtdIns(4,5)P2-mediated cell signaling: emerging principles and PTEN as a paradigm for regulatory mechanism. Adv Exp Med Biol 991:85-104
Shenoy, Siddharth; Shekhar, Prabhanshu; Heinrich, Frank et al. (2012) Membrane association of the PTEN tumor suppressor: molecular details of the protein-membrane complex from SPR binding studies and neutron reflection. PLoS One 7:e32591

Showing the most recent 10 out of 64 publications