Glioblastoma is one of the most challenging forms of cancer to treat. Here we describe a computational platform that integrates the analysis of copy number variations and somatic mutations and ...unravels the landscape of in-frame gene fusions in glioblastoma. We found mutations with loss of heterozygosity in LZTR1, encoding an adaptor of CUL3-containing E3 ligase complexes. Mutations and deletions disrupt LZTR1 function, which restrains the self renewal and growth of glioma spheres that retain stem cell features. Loss-of-function mutations in CTNND2 target a neural-specific gene and are associated with the transformation of glioma cells along the very aggressive mesenchymal phenotype. We also report recurrent translocations that fuse the coding sequence of EGFR to several partners, with EGFR-SEPT14 being the most frequent functional gene fusion in human glioblastoma. EGFR-SEPT14 fusions activate STAT3 signaling and confer mitogen independence and sensitivity to EGFR inhibition. These results provide insights into the pathogenesis of glioblastoma and highlight new targets for therapeutic intervention.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The existence of treatment-resistant cancer stem cells contributes to the aggressive phenotype of glioblastoma. However, the molecular alterations that drive stem cell proliferation in these tumors ...remain unknown. In this study, we found that expression of the MET oncogene was associated with neurospheres expressing the gene signature of mesenchymal and proneural subtypes of glioblastoma. Met expression was almost absent from neurospheres expressing the signature of the classical subtype and was mutually exclusive with amplification and expression of the EGF receptor (EGFR) gene. Met-positive and Met-negative neurospheres displayed distinct growth factor requirements, differentiated along divergent pathways, and generated tumors with distinctive features. The Met(high) subpopulation within Met-pos neurospheres displayed clonogenic potential and long-term self-renewal ability in vitro and enhanced growth kinetics in vivo. In Met(high) cells, the Met ligand HGF further sustained proliferation, clonogenicity, expression of self-renewal markers, migration, and invasion in vitro. Together, our findings suggest that Met is a functional marker of glioblastoma stem cells and a candidate target for identification and therapy of a subset of glioblastomas.
Recent data suggest that circulating endothelial and progenitor cells (CECs and CEPs, respectively) may have predictive potential in cancer patients treated with bevacizumab, the antibody recognizing ...vascular endothelial growth factor (VEGF). Here we report on CECs and CEPs investigated in 68 patients affected by recurrent glioblastoma (rGBM) treated with bevacizumab and irinotecan and two Independent Datasets of rGBM patients respectively treated with bevacizumab alone (n=32, independent dataset A: IDA) and classical antiblastic chemotherapy (n=14, independent dataset B: IDB).
rGBM patients with KPS ≥50 were treated until progression, as defined by MRI with RANO criteria. CECs expressing CD109, a marker of tumor endothelial cells, as well as other CEC and CEP subtypes, were investigated by six-color flow cytometry.
A baseline count of CD109+ CEC higher than 41.1/ml (1(st) quartile) was associated with increased progression free survival (PFS; 20 versus 9 weeks, P=0.008) and overall survival (OS; 32 versus 23 weeks, P=0.03). Longer PFS (25 versus 8 weeks, P=0.02) and OS (27 versus 17 weeks, P=0.03) were also confirmed in IDA with CD109+ CECs higher than 41.1/ml but not in IDB. Patients treated with bevacizumab with or without irinotecan that were free from MRI progression after two months of treatment had significant decrease of CD109+ CECs: median PFS was 19 weeks; median OS 29 weeks. The presence of two non-contiguous lesions (distant disease) at baseline was an independent predictor of shorter PFS and OS (P<0.001).
Data encourage further studies on the predictive potential of CD109+ CECs in GBM patients treated with bevacizumab.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The brain tumor glioblastoma multiforme (GBM) is among the most lethal forms of human cancer. Here, we report that a small subset of GBMs (3.1%; 3 of 97 tumors examined) harbors oncogenic chromosomal ...translocations that fuse in-frame the tyrosine kinase coding domains of fibroblast growth factor receptor (FGFR) genes (FGFR1 or FGFR3) to the transforming acidic coiled-coil (TACC) coding domains of TACC1 or TACC3, respectively. The FGFR-TACC fusion protein displays oncogenic activity when introduced into astrocytes or stereotactically transduced in the mouse brain. The fusion protein, which localizes to mitotic spindle poles, has constitutive kinase activity and induces mitotic and chromosomal segregation defects and triggers aneuploidy. Inhibition of FGFR kinase corrects the aneuploidy, and oral administration of an FGFR inhibitor prolongs survival of mice harboring intracranial FGFR3-TACC3—initiated glioma. FGFR-TACC fusions could potentially identify a subset of GBM patients who would benefit from targeted FGFR kinase inhibition.
Medulloblastoma (MB) comprises a group of heterogeneous paediatric embryonal neoplasms of the hindbrain with strong links to early development of the hindbrain
. Mutations that activate Sonic ...hedgehog signalling lead to Sonic hedgehog MB in the upper rhombic lip (RL) granule cell lineage
. By contrast, mutations that activate WNT signalling lead to WNT MB in the lower RL
. However, little is known about the more commonly occurring group 4 (G4) MB, which is thought to arise in the unipolar brush cell lineage
. Here we demonstrate that somatic mutations that cause G4 MB converge on the core binding factor alpha (CBFA) complex and mutually exclusive alterations that affect CBFA2T2, CBFA2T3, PRDM6, UTX and OTX2. CBFA2T2 is expressed early in the progenitor cells of the cerebellar RL subventricular zone in Homo sapiens, and G4 MB transcriptionally resembles these progenitors but are stalled in developmental time. Knockdown of OTX2 in model systems relieves this differentiation blockade, which allows MB cells to spontaneously proceed along normal developmental differentiation trajectories. The specific nature of the split human RL, which is destined to generate most of the neurons in the human brain, and its high level of susceptible EOMES
KI67
unipolar brush cell progenitor cells probably predisposes our species to the development of G4 MB.
miR-145 is an important repressor of pluripotency in embryonic stem cells and a tumor suppressor in different cancers. Here, we found that miR-145 is strongly down-regulated in glioblastoma (GB) ...specimens and corresponding glioblastomaneurospheres (GB-NS, containing GB stem-like cells) compared to normal brain (NB) and to low-grade gliomas (LGG). We observed a direct correlation between miR-145 expression and the progression-free survival (PFS) in LGG patients and overall survival (OS) in GB patients. Using microarray analysis, we identified relevant differences in gene expression profiles between GB-NS over-expressing miR-145 (miRover-NS) and GB-NS Empty (Empty-NS). We focused our attention on HEF1/Cas-L/NEDD9, a scaffold protein involved in invasion in several types of cancer. We confirmed a significant down-regulation of NEDD9 in miRover-NS and we found a higher expression in GB and GB-NS compared to NB. Approximately 50% of LGG patients expressed higher levels of NEDD9 than NB, and the PFS of such patients was shorter than in patients expressing lower levels of NEDD9. We observed that intracranial injection of GB-NS over-expressing miR-145 delays significantly tumor development :deriving tumors showed a significant down-regulation of NEDD9. In addition, we demonstrated a significant inhibition of invasion in silencing experiments with GB-NS shNEDD9 (shNEDD9), and an up-regulation of miR-145 in shNEDD9, suggesting a doublenegative feedback loop between miR-145 and NEDD9. Our results demonstrate the critical role of miR-145 and NEDD9 in regulating glioblastoma invasion and suggest a potential role of NEDD9 as a biomarker for glioma progression.
The NF-kB family of transcription factors is up-regulated in inflammation and different cancers. Recent data described heterozygous deletions of the NF-kB Inhibitor alpha gene (NFKBIA) in about 20% ...of glioblastomas (GBM): deletions were mutually exclusive with epidermal growth factor receptor (EGFR) amplification, a frequent event in GBM. We assessed the status of NFKBIA and EGFR in 69 primary GBMs and in corresponding neurospheres (NS). NFKBIA deletion was investigated by the copy number variation assay (CNV); EGFR amplification by CNV ratio with HGF; expression of EGFR and EGFRvIII by quantitative PCR or ReverseTranscriptase PCR. Heterozygous deletions of NFKBIA were present in 3 of 69 primary GBMs and, surprisingly, in 30 of 69 NS. EGFR amplification was detected in 36 GBMs: in corresponding NS, amplification was lost in 13 cases and reduced in 23 (10 vs 47 folds in NS vs primary tumors; p < 0.001). The CNV assay was validated investigating HPRT1 on chromosome X in females and males. Results of array-CGH performed on 3 primary GBMs and 1 NS line were compatible with the CNV assay. NS cells with NFKBIA deletion had increased nuclear activity of p65 (RelA) and increased expression of the NF-kB target IL-6. In absence of EGF in the medium, EGFR amplification was more conserved and NFKBIA deletion less frequent point to a low frequency of NFKBIA deletions in GBM and suggest that EGF in the culture medium of NS may affect frequency not only of EGFR amplifications but also of NFKBIA deletions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract only
2083
Background: Bevacizumab, an anti-VEGF antibody, has shown significant activity in high grade gliomas (HGG). However, tumor recurrence inevitably occurs. Methods: We treated 63 ...recurrent HGG patients with poor prognostic factors with bevacizumab (10 mg/kg) and irinotecan (125 or 340 mg/m
2
) every 2 weeks, and investigated IL-12, IL-13, IL-17, FGF basic, G-CSF, MIP-1b, PDGF-beta, plasma levels before starting treatment and every 8 weeks by Bioplex. Ten age- and sex-matched healthy controls were used for comparison. Results: After a median follow-up of 27 weeks, median OS and PFS were 33 and 18 weeks, respectively. PFS at 6 and 12 months were 32% and 12%, respectively. OS at 6 months was 60%. Toxicity was mild. Baseline higher amounts of IL-13 (48±174 pg/ml vs 3.44±0.9 pg/ml, p=0.0001) and lower amounts of MIP-1b (35.3±20.9 pg/ml vs 67.2±18.8 pg/ml, p=0.0002), PDGF-beta (1585.5±1585 pg/ml vs 7098±1585 pg/ml, p=0.0001) and VEGF (27±39.8 pg/ml vs 54.5±32 pg/ml, p=0.001) were detected in patients than in healthy controls. In a cohort of 15 non-responders (patients who progressed 8 weeks after treatment onset), baseline IL-8 (15.7±10.8 pg/ml vs 10.9±9.4 pg/ml, p=0.03) and G-CSF (113.3±54 pg/ml vs 84.9±59.2 pg/ml, p=0.03) were significantly higher than in patients responding to treatment. In the same cohort no significant reduction of VEGF and other cytokines was observed after 8 weeks of treatment, while a decrease of plasma VEGF was observed in the remaining patients (26±32 pg/ml vs 13.3±28.5 pg/ml, p=0.001). Furthermore, in a cohort of 22 long-term responders (patients who progressed after more than 18 weeks of treatment), levels of VEGF decreased after 8 weeks of treatment when compared to baseline, whereas no difference was observed in baseline levels (23.9±22.6 pg/ml vs 9.8±9.4 pg/ml, p=0.001). Conclusions: Data suggest that high levels of IL-8 and G-CSF at baseline associated with a lack of VEGF decrease after 8 weeks of treatment identify patients who are resistant to bevacizumab. This hypothesis should be tested in a large number of patients.
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