IKK/NF-κB signaling contributes to glioblastoma stem cell maintenance

// Amanda L. Rinkenbaugh 1,2 , Patricia C. Cogswell 2,3 , Barbara Calamini 4 , Denise E. Dunn 4 , Anders I. Persson 5,6 , William A. Weiss 5,6 , Donald C. Lo 4 and Albert S. Baldwin 2 1 Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, USA 2 Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA 3 Chordoma Foundation, Durham, NC, USA 4 Center for Drug Discovery and Department of Neurobiology, Duke University Medical Center, Durham, NC, USA 5 Helen Diller Family Comprehensive Cancer Center and Department of Neurology, University of California, San Francisco, CA, USA 6 Department of Neurological Surgery and Brain Tumor Research Center, University of California, San Francisco, CA, USA Correspondence to: Albert Baldwin, email: // Keywords : NF-κB, glioblastoma, cancer stem cells, tumor-initiating cells Received : March 14, 2016 Accepted : September 24, 2016 Published : October 06, 2016 Abstract Glioblastoma multiforme (GBM) carries a poor prognosis and continues to lack effective treatments. Glioblastoma stem cells (GSCs) drive tumor formation, invasion, and drug resistance and, as such, are the focus of studies to identify new therapies for disease control. Here, we identify the involvement of IKK and NF-κB signaling in the maintenance of GSCs. Inhibition of this pathway impairs self-renewal as analyzed in tumorsphere formation and GBM expansion as analyzed in brain slice culture. Interestingly, both the canonical and non-canonical branches of the NF-κB pathway are shown to contribute to this phenotype. One source of NF-κB activation in GBM involves the TGF-β/TAK1 signaling axis. Together, our results demonstrate a role for the NF-κB pathway in GSCs and provide a mechanistic basis for its potential as a therapeutic target in glioblastoma

Therapeutically engineered induced neural stem cells are tumour-homing and inhibit progression of glioblastoma

Transdifferentiation (TD) is a recent advancement in somatic cell reprogramming. The direct conversion of TD eliminates the pluripotent intermediate state to create cells that are ideal for personalized cell therapy. Here we provide evidence that TD-derived induced neural stem cells (iNSCs) are an efficacious therapeutic strategy for brain cancer. We find that iNSCs genetically engineered with optical reporters and tumouricidal gene products retain the capacity to differentiate and induced apoptosis in co-cultured human glioblastoma cells. Time-lapse imaging shows that iNSCs are tumouritropic, homing rapidly to co-cultured glioblastoma cells and migrating extensively to distant tumour foci in the murine brain. Multimodality imaging reveals that iNSC delivery of the anticancer molecule TRAIL decreases the growth of established solid and diffuse patient-derived orthotopic glioblastoma xenografts 230- and 20-fold, respectively, while significantly prolonging the median mouse survival. These findings establish a strategy for creating autologous cell-based therapies to treat patients with aggressive forms of brain cancer

Oncogenic EGFR Signaling Activates an mTORC2-NF- B Pathway That Promotes Chemotherapy Resistance

Although it is known that mTOR complex 2 (mTORC2) functions upstream of Akt, the role of this protein kinase complex in cancer is not well understood. Through an integrated analysis of cell lines, in vivo models and clinical samples, we demonstrate that mTORC2 is frequently activated in glioblastoma (GBM), the most common malignant primary brain tumor of adults. We show that the common activating epidermal growth factor receptor (EGFR) mutation (EGFRvIII) stimulates mTORC2 kinase activity, which is partially suppressed by PTEN. mTORC2 signaling promotes GBM growth and survival, and activates NF-κB. Importantly, this mTORC2-NF-κB pathway renders GBM cells and tumors resistant to chemotherapy in a manner independent of Akt. These results highlight the critical role of mTORC2 in GBM pathogenesis, including through activation of NF-κB downstream of mutant EGFR, leading to a previously unrecognized function in cancer chemotherapy resistance. These findings suggest that therapeutic strategies targeting mTORC2, alone or in combination with chemotherapy, will be effective in cancer

Roles of the NF-kappaB Pathway in Glioblastoma Stem Cells and Chordoma

The NF-κB pathway consists of a family of five transcription factors: RelA/p65, RelB, c-Rel, p100/p52, and p105/p50. Originally discovered for its involvement in inflammation and immune signaling, aberrant constitutive NF-κB activation is seen in many tumor types. NF-κB-dependent target gene regulation mediates several hallmarks of cancer, including survival, suppression of apoptosis, and invasion. This work examines NF-κB signaling in both glioblastoma and chordoma samples. In the first project, NF-κB is found to mediate cancer stem cell maintenance in glioblastoma explants. Both genetic and pharmacological NF-κB inhibition impair neurosphere formation at limiting dilutions. Use of an ex vivo brain slice co-culture model confirmed the in vitro findings, providing a novel platform for drug testing in glioblastoma studies that bridges the gap between cell culture and intracranial animal models. In the second project, NF-κB regulates proliferation and invasion of chordoma cell lines. Due to the rarity of chordomas, these tumors have not been well- characterized at a molecular level. These results provide some of the early evidence for NF- κB activation, potentially through regulation of IL-6, IL-8, and MMP9. Both of these studies suggest that IKK/NF-κB inhibition could provide therapeutic benefit in glioblastoma and chordoma, affecting multiple phenotypes that drive the poor prognosis of these tumors.Doctor of Philosoph

The NF-κB Pathway and Cancer Stem Cells

The NF-κB transcription factor pathway is a crucial regulator of inflammation and immune responses. Additionally, aberrant NF-κB signaling has been identified in many types of cancer. Downstream of key oncogenic pathways, such as RAS, BCR-ABL, and Her2, NF-κB regulates transcription of target genes that promote cell survival and proliferation, inhibit apoptosis, and mediate invasion and metastasis. The cancer stem cell model posits that a subset of tumor cells (cancer stem cells) drive tumor initiation, exhibit resistance to treatment, and promote recurrence and metastasis. This review examines the evidence for a role for NF-κB signaling in cancer stem cell biology

IKK/NF-κB signaling contributes to glioblastoma stem cell maintenance.

Glioblastoma multiforme (GBM) carries a poor prognosis and continues to lack effective treatments. Glioblastoma stem cells (GSCs) drive tumor formation, invasion, and drug resistance and, as such, are the focus of studies to identify new therapies for disease control. Here, we identify the involvement of IKK and NF-κB signaling in the maintenance of GSCs. Inhibition of this pathway impairs self-renewal as analyzed in tumorsphere formation and GBM expansion as analyzed in brain slice culture. Interestingly, both the canonical and non-canonical branches of the NF-κB pathway are shown to contribute to this phenotype. One source of NF-κB activation in GBM involves the TGF-β/TAK1 signaling axis. Together, our results demonstrate a role for the NF-κB pathway in GSCs and provide a mechanistic basis for its potential as a therapeutic target in glioblastoma

Predictors of success in establishing orthotopic patient-derived xenograft models of triple negative breast cancer

Abstract Patient-derived xenograft (PDX) models of breast cancer are an effective discovery platform and tool for preclinical pharmacologic testing and biomarker identification. We established orthotopic PDX models of triple negative breast cancer (TNBC) from the primary breast tumors of patients prior to and following neoadjuvant chemotherapy (NACT) while they were enrolled in the ARTEMIS trial (NCT02276443). Serial biopsies were obtained from patients prior to treatment (pre-NACT), from poorly responsive disease after four cycles of Adriamycin and cyclophosphamide (AC, mid-NACT), and in cases of AC-resistance, after a 3-month course of different experimental therapies and/or additional chemotherapy (post-NACT). Our study cohort includes a total of 269 fine needle aspirates (FNAs) from 217 women, generating a total of 62 PDX models (overall success-rate = 23%). Success of PDX engraftment was generally higher from those cancers that proved to be treatment-resistant, whether poorly responsive to AC as determined by ultrasound measurements mid-NACT (p = 0.063), RCB II/III status after NACT (p = 0.046), or metastatic relapse within 2 years of surgery (p = 0.008). TNBC molecular subtype determined from gene expression microarrays of pre-NACT tumors revealed no significant association with PDX engraftment rate (p = 0.877). Finally, we developed a statistical model predictive of PDX engraftment using percent Ki67 positive cells in the patient’s diagnostic biopsy, positive lymph node status at diagnosis, and low volumetric reduction of the patient’s tumor following AC treatment. This novel bank of 62 PDX models of TNBC provides a valuable resource for biomarker discovery and preclinical therapeutic trials aimed at improving neoadjuvant response rates for patients with TNBC