Clinicopathological and molecular landscape of 5-year IDH-wild-type glioblastoma survivors: A multicentric retrospective study

Five-year glioblastoma (GBM) survivors (LTS) are the minority of the isocitrate dehydrogenase (IDH)-wild-type GBM patients, and their molecular fingerprint is still largely unexplored. This multicenter retrospective study analyzed a large LTS-GBM cohort from nine Italian institutions and molecularly characterized a subgroup of patients by mutation, DNA methylation (DNAm) and copy number variation (CNV) profiling, comparing it to standard survival GBM. Mutation scan allowed the identification of pathogenic variants in most cases, showing a similar mutational spectrum in both groups, and highlighted TP53 as the most commonly mutated gene in the LTS group. We confirmed DNAm as a valuable tool for GBM classification with a diagnostic refinement by using brain tumor classifier v12.5. LTS were more heterogeneous with more cases classified as diffuse pediatric high-grade glioma subtypes and having peculiar CNVs. We observed a global higher methylation in CpG islands and in gene promoters of LTS with methylation levels of distinct gene promoters correlating with prognosis.

Microglial Senescence and Activation in Healthy Aging and Alzheimer's Disease: Systematic Review and Neuropathological Scoring

The greatest risk factor for neurodegeneration is the aging of the multiple cell types of human CNS, among which microglia are important because they are the "sentinels" of internal and external perturbations and have long lifespans. We aim to emphasize microglial signatures in physiologic brain aging and Alzheimer's disease (AD). A systematic literature search of all published articles about microglial senescence in human healthy aging and AD was performed, searching for PubMed and Scopus online databases. Among 1947 articles screened, a total of 289 articles were assessed for full-text eligibility. Microglial transcriptomic, phenotypic, and neuropathological profiles were analyzed comprising healthy aging and AD. Our review highlights that studies on animal models only partially clarify what happens in humans. Human and mice microglia are hugely heterogeneous. Like a two-sided coin, microglia can be protective or harmful, depending on the context. Brain health depends upon a balance between the actions and reactions of microglia maintaining brain homeostasis in cooperation with other cell types (especially astrocytes and oligodendrocytes). During aging, accumulating oxidative stress and mitochondrial dysfunction weaken microglia leading to dystrophic/senescent, otherwise over-reactive, phenotype-enhancing neurodegenerative phenomena. Microglia are crucial for managing Aβ, pTAU, and damaged synapses, being pivotal in AD pathogenesis.

Are Thalamic Intrinsic Lesions Operable? No-Man's Land Revisited by the Analysis of a Large Retrospective, Mono-Institutional, Cohort

Thalamic gliomas represent a heterogeneous subset of deep-seated lesions for which surgical removal is advocated, although clear prognostic factors linked to advantages in performance status or overall survival are still lacking. We reviewed our Institutional Cancer Registry, identifying patients who underwent surgery for thalamic gliomas between 2006 and 2020. Associations between possible prognostic factors such as tumor volume, grade, the extent of resection and performance status (PS), and overall survival (OS) were evaluated using univariate and multivariate survival analyses. We found 56 patients: 31 underwent surgery, and 25 underwent biopsy. Compared to biopsy, surgery resulted positively associated with an increase in the OS (hazard ratio, HR, at multivariate analysis 0.30, 95% confidence interval, CI, 0.12-0.75). Considering the extent of resection (EOR), obtaining GTR/STR appeared to offer an OS advantage in high-grade gliomas (HGG) patients submitted to surgical resection if compared to biopsy, although we did not find statistical significance at multivariate analysis (HR 0.53, 95% CI 0.17-1.59). Patients with a stable 3-month KPS after surgery demonstrated to have a better prognosis in terms of OS if compared to biopsy (multivariate HR 0.17, 95% CI, 0.05-0.59). Age and histological grades were found to be prognostic factors for this condition (p = 0.04 and p = 0.004, respectively, chi-square test). Considering the entire cohort, p53 positivity (univariate HR 2.21, 95% CI 1.01-4.82) and ATRX positivity (univariate HR 2.69, 95% CI 0.92-7.83) resulted associated with a worse prognosis in terms of OS. In this work, we demonstrated that surgery aimed at tumor resection might offer a stronger survival advantage when a stable 3-month KPS after surgery is achieved.

EPCO-02. GENOME-WIDE DNA METHYLATION PROFILING AND GENETIC CHARACTERIZATION OF LONG-TERM SURVIVAL IDH WILD-TYPE GLIOBLASTOMA PATIENTS

Glioblastoma multiforme (GBM) has a dismal outcome of approximately 12 months. Less than 5% of patients (long-term survivors-LTS) survives more than 5-years, including IDH-mutant gliomas. Nevertheless, the molecular fingerprint of LTS remains largely uncharted. DNA methylation (DNAm) is an epigenetic modification, altered in cancer and used to classify brain tumors. In this multicentric study sponsored by Alleanza Contro il Cancro (ACC) network, we aimed to molecularly characterize LTS vs standard survival GBM (CTR) by DNAm/Copy Number Variation (CNV) and mutation profiling. We analyzed 51 IDHwt GBM samples (27LTS/24CTR) by Illumina EPIC beadChip and AmpliSeq Comprehensive Cancer Panel. We ran methylation data through the brain tumor classifiers v11b4 and v12.5, performed multidimensional scaling analysis and investigated differentially methylated regions (DMR) correlating them with survival. According to v11b4, cases were classified as: 43 GBM IDHwt (22LTS/21CTR), 27 with a calibrated score >0.84 (16LTS); Plexus Tumor with low scores (2LTS/3CTR); 3 LTS samples did not match. A diagnostic refinement was observed by the v12.5, with 48 cases classifying as GBM IDHwt (25LTS/23CTR) and 35 (19LTS) with optimal score. The LTS group was more heterogeneous, with 4 cases matching in the pedHGG subtypes, including 2 cases in young adults, one with high tumor mutational burden and MSH6 mutation. No specific DNAm genomic profile was observed for LTS patients but we identified 18 significant DMRs, 4 associated with survival probability. At CNV analysis, most cases showed classical alterations (Chr7 gain with or w/o EGFR amplification, 9p21 loss, Chr10 loss) while pedHGG were associated with PDGFRA amplification, 1q gain, 13q loss. NGS identified at least 1 pathogenic variant in 40 cases (22CTR/18LTS) and showed a higher prevalence of mutation negative cases among LTS. No significant difference between the 2 groups was observed in terms of prevalence of mutated genes or number of VUS per sample.

P11.68.A Hemangiopericytoma, case series and clinic-pathological analysis

Background

Hemangiopericytoma (HPC) is an extremely rare aggressive tumor of mesenchymal origin, which constitutes less than 1% of primary tumors of the central nervous system. Typically it occurs in young adults (mean age at diagnosis 30-50 years). Initially described as gemmangiomas, was first called hemangiopericytoma in 1942 but it was considered as a variant of meningioma until 1993 when it was finally recognized as a distinct clinical-pathological entity by the World Health Organization (WHO). In 2016, there was the unification of both HPC and Solitary Fibrous Tumor (SFT) in a single spectrum of rare and thick mesenchymal tumors due to the identification, in both tumoral types, of a molecular alteration called NAB2-STAT6 fusion.

Material and Methods

The present study is a case series of patients that received a pathological diagnosis of SFT/HPC at our Institute from 1981 to 2020. Clinical data included: demographic data, tumor characteristics and treatment modality. Hystological diagnosis and immunohistochemistry allowed to confirm diagnosis, based on the 2016 WHO classification. Haematoxylin staining was completed with immunohistochemistry with primary antibodies for STAT 6 and evaluation of presence of tumor necrosis. Statistical analysis was conducted considering age at first diagnosis, treatment modality, extent of tumor resection, presence of necrosis in histological analysis compared to PFS-1, OS and relapses number.

Results

The case series was composed by 82 patients (46 men and 36 women) with median age of 43 (± 20) that accede to our Institute from 1981 to 2020. Our statistical analysis showed significative correlation between age, extend of tumor resection and presence of necrosis with OS and relapses number.

Conclusion

Hemangiopericytoma is a very rare cerebral tumors, and for this reason large case series are not disposable in literature. In our study we collected all disposable data of every patient with pathological diagnosis of SFT/HPC acceded to our hospital in the long period of 39 years in the aim to verify the presence of significative correlations. We observed strong correlation between tumor resection and presence of necrosis in tumor tissue with prognosis parameters (OS and number of relapses). This result it could be important to conduct the decisional process about treatment after surgical resection, considering also pathological features, rather than only surgical resection.

Pleomorphic xanthoastrocytoma is a heterogeneous entity with pTERT mutations prognosticating shorter survival

Pleomorphic xanthoastrocytoma (PXA) in its classic manifestation exhibits distinct morphological features and is assigned to CNS WHO grade 2 or grade 3. Distinction from glioblastoma variants and lower grade glial and glioneuronal tumors is a common diagnostic challenge. We compared a morphologically defined set of PXA (histPXA) with an independent set, defined by DNA methylation analysis (mcPXA). HistPXA encompassed 144 tumors all subjected to DNA methylation array analysis. Sixty-two histPXA matched to the methylation class mcPXA. These were combined with the cases that showed the mcPXA signature but had received a histopathological diagnosis other than PXA. This cohort constituted a set of 220 mcPXA. Molecular and clinical parameters were analyzed in these groups. Morphological parameters were analyzed in a subset of tumors with FFPE tissue available. HistPXA revealed considerable heterogeneity in regard to methylation classes, with methylation classes glioblastoma and ganglioglioma being the most frequent mismatches. Similarly, the mcPXA cohort contained tumors of diverse histological diagnoses, with glioblastoma constituting the most frequent mismatch. Subsequent analyses demonstrated the presence of canonical pTERT mutations to be associated with unfavorable prognosis among mcPXA. Based on these data, we consider the tumor type PXA to be histologically more varied than previously assumed. Histological approach to diagnosis will predominantly identify cases with the established archetypical morphology. DNA methylation analysis includes additional tumors in the tumor class PXA that share similar DNA methylation profile but lack the typical morphology of a PXA. DNA methylation analysis also assist in separating other tumor types with morphologic overlap to PXA. Our data suggest the presence of canonical pTERT mutations as a robust indicator for poor prognosis in methylation class PXA.

Prognostic Characterization of Higher-Grade Meningiomas: A Histopathological Score to Predict Progression and Outcome

Higher-grade meningiomas (WHO grade II and III) represent a diagnostic and prognostic challenge. We assessed the pathological and molecular characteristics of 94 higher-grade meningiomas (85 grade II, 9 grade III) to identify novel prognostic parameters. Higher mitotic count (p = 0.018), diffuse (≥50%) prominent nucleoli (p < 0.001), and sheeting (p < 0.001) were associated with recurrence. Lower SSTR2a-positive cells median rate (p = 0.048) and TERT promoter mutations (p = 0.014) were associated with recurrence and patient death, respectively; further analyses did not identify other outcome associations. Presence of Ki67 hot spots was associated with a shorter progression-free survival (PFS), independently of WHO grade at multivariate analysis (HR = 3.35, p = 0.008). Necrosis was related to a poorer overall survival (OS) at univariate (focal: HR = 4.55, p = 0.041 and diffuse: HR = 7.38, p = 0.020) and Kaplan-Meier analyses. A prognostic score was designed based on previous results: Presence of diffuse (≥50%) prominent nucleoli (0/1 point), diffuse (≥50%) sheeting (0/1 point), focal (<50%) or diffuse (≥50%) necrosis (0/1/2 points), and Ki67 hot spots (0/1 point). A total score ≥4 predicted poorer PFS and OS by Kaplan-Meier (PFS: 1.7 vs 6.4 years, p < 0.001 and OS: 5.2 vs 10.8 years, p = 0.001) and multivariate (PFS: HR = 5.98, p < 0.001 and OS: HR = 2.99, p = 0.048) analyses. These results were confirmed in an independent series of 58 grade II meningiomas (PFS: HR = 7.22, p = 0.002 and OS: HR = 9.69, p = 0.003). These associations and the integrated score could complement WHO grading.

MNGI-07. TRIMETHYLATED H3K27 AND EZH2 EXPRESSION IN MENINGIOMA: CORRELATION WITH TENDENCY TO RECUR

Meningiomas are the most frequent primary CNS tumors, usually benign (WHO grade I), but in the 25–30% more aggressive tumors (grade II-III). Histopathological criteria (WHO 2016) are unsatisfactory to recognize meningiomas with tendency to recur. Recent studies have identified some mutations associated with histological features and location (i.e. BAP1 mutation in rhabdoid subtype), while risk stratification schemes based on DNA methylation subgroups have been proposed. Epigenetic modifications of histones play a pivotal role in tumorigenesis, the methylation of lysine 27 (K27) of histone H3 controlled by EZH2 subunit of PRC2 complex. BAP1 could be also involved in epigenetic regulation of PRC2 complex. The deregulation of H3K27 methylation has been found associated with recurrence risk in grade II meningiomas. Aim of the present study was to evaluate histone H3 methylation profile in a group of meningiomas of different grade with follow-up longer than 10 years, comparing non-recurrent to recurrent ones. We performed an immunohistochemical study on 145 meningiomas (50 grade I, 80 grade II and 15 grade III), investigating the expression of trimethylated H3K27 (H3K27me3), EZH2 and BAP1. The results were related to clinical data obtained from our Institutional Tumor Registry and evaluation of clinical reports. We observed a loss of H3K27me3 expression only in grade II and III meningiomas in 18% of cases, without correlation with tendency to recur. EZH2 showed increased percentage of positive nuclei related to the grade. In the group of grade I meningioma EZH2 expression was associated to recurrences. We didn’t observe loss of BAP1 expression. In conclusion, our data suggest that immunohistochemical evaluation of H3K27me3 and EZH2 could be a useful tool to better stratify meningioma with high risk of recurrence. Moreover, EZH2 could be of interest as therapeutic target. Molecular investigations in a larger cohort are needed to confirm these results.

Long and Very-Long-Chain Ceramides Correlate with A More Aggressive Behavior in Skull Base Chordoma Patients

BACKGROUND

Skull base chordomas are rare tumors arising from notochord. Sphingolipids analysis is a promising approach in molecular oncology, and it has never been applied in chordomas. Our aim is to investigate chordoma behavior and the role of ceramides.

METHODS

Ceramides were extracted and evaluated by liquid chromatography and mass spectrometry in a cohort of patients with a skull base chordoma. Clinical data were also collected and correlated with ceramide levels. Linear regression and correlation analyses were conducted.

RESULTS

Analyzing the association between ceramides level and MIB-1, total ceramides and dihydroceramides showed a strong association (r = 0.7257 and r = 0.6733, respectively) with MIB-1 staining (p = 0.0033 and p = 0.0083, respectively). Among the single ceramide species, Cer C24:1 (r = 0.8814, p ≤ 0.0001), DHCer C24:1 (r = 0.8429, p = 0.0002) and DHCer C18:0 (r = 0.9426, p ≤ 0.0001) showed a significant correlation with MIB-1.

CONCLUSION

Our lipid analysis showed ceramides to be promising tumoral biomarkers in skull base chordomas. Long- and very-long-chain ceramides, such as Cer C24:1 and DHCer C24:1, may be related to a prolonged tumor survival and aggressiveness, and the understanding of their effective biological role will hopefully shed light on the mechanisms of chordoma radio-resistance, tendency to recur, and use of agents targeting ceramide metabolism.

P09.03 Array-CGH analysis in meningiomas adds further information of biological behavior

BACKGROUND

Meningioma is the most common primary tumor of CNS, usually a benign tumor (grade I) successfully treated by surgical resection, while in the 25–30% of cases is a more aggressive neoplasm with high recurrence rate and poor prognosis (grade II-III). In the last years some studies tried to investigate the genomic profile of meningioma to find additional prognostic factors and potential therapeutic targets. Aim of our study was to use the array-CGH (aCGH) to investigate possible indicators of recurrence risk in meningiomas.

MATERIAL AND METHODS

We retrospectively selected two group of patients: 34 with meningioma WHO grade I (24 F, 10 M, median age at diagnosis 56 yrs) and 19 with meningioma WHO grade II (9 F, 10 M, median age 59 yrs), in order to compare cases recurrent and non-recurrent in each group. We also analyzed 5/18 recurrences WHO grade I and 10/11 WHO grade II. Genomic profiles were investigated by aCGH.

RESULTS

We observed an increase in number of genomic imbalances related to grading and in non-recurrent versus recurrent tumors. 9 WHO I meningiomas were without alterations. The mainly alterations observed were deletions and duplications, moreover we also identified chromothripsis of a single chromosome in 2/18 WHO I recurrent and 2/8 WHO II non recurrent meningiomas, and chromothripsis of multiple chromosomes in 5/11 WHO II recurrent meningiomas. As well we detected the presence of mosaicism, mainly in WHO I recurrent and in grade II meningiomas. In 7/14 WHO I meningiomas we found differences in genomic profile analyzing two samples obtained from two distinct areas. 6/15 recurrences showed the same alterations of the primary tumor. We didn’t detected an association between alteration of 1p and 22q and recurrence risk, as previously suggested, as those were the most diffused imbalances in all meningiomas.

CONCLUSION

In our patients we found a difference in genomic imbalances between grade I and grade II meningiomas, but we also identified additional details of the complexity of alterations in meningioma with the detection of chromothripsis and mosaicism. This latter aspect is a new issue and suggests the presence of more aggressive cell clones that could be predictive of recurrence in grade I meningioma. Moreover, we observed a spatial heterogeneity in half of grade I meningioma analyzed. Our preliminary results suggest that the aCGH, a technique routinely used in many laboratories, could be used to better stratify meningioma patients.

Comprehensive, Integrative Genomic Analysis of Diffuse Lower-Grade Gliomas

BACKGROUND

Diffuse low-grade and intermediate-grade gliomas (which together make up the lower-grade gliomas, World Health Organization grades II and III) have highly variable clinical behavior that is not adequately predicted on the basis of histologic class. Some are indolent; others quickly progress to glioblastoma. The uncertainty is compounded by interobserver variability in histologic diagnosis. Mutations in IDH, TP53, and ATRX and codeletion of chromosome arms 1p and 19q (1p/19q codeletion) have been implicated as clinically relevant markers of lower-grade gliomas.

METHODS

We performed genomewide analyses of 293 lower-grade gliomas from adults, incorporating exome sequence, DNA copy number, DNA methylation, messenger RNA expression, microRNA expression, and targeted protein expression. These data were integrated and tested for correlation with clinical outcomes.

RESULTS

Unsupervised clustering of mutations and data from RNA, DNA-copy-number, and DNA-methylation platforms uncovered concordant classification of three robust, nonoverlapping, prognostically significant subtypes of lower-grade glioma that were captured more accurately by IDH, 1p/19q, and TP53 status than by histologic class. Patients who had lower-grade gliomas with an IDH mutation and 1p/19q codeletion had the most favorable clinical outcomes. Their gliomas harbored mutations in CIC, FUBP1, NOTCH1, and the TERT promoter. Nearly all lower-grade gliomas with IDH mutations and no 1p/19q codeletion had mutations in TP53 (94%) and ATRX inactivation (86%). The large majority of lower-grade gliomas without an IDH mutation had genomic aberrations and clinical behavior strikingly similar to those found in primary glioblastoma.

CONCLUSIONS

The integration of genomewide data from multiple platforms delineated three molecular classes of lower-grade gliomas that were more concordant with IDH, 1p/19q, and TP53 status than with histologic class. Lower-grade gliomas with an IDH mutation either had 1p/19q codeletion or carried a TP53 mutation. Most lower-grade gliomas without an IDH mutation were molecularly and clinically similar to glioblastoma. (Funded by the National Institutes of Health.).

Increased migration of a human glioma cell line after in vitro CyberKnife irradiation

A human glioblastoma multiforme cell line (U87) and its derived-spheroids were irradiated either using a conventional irradiation (CIR) or a CK-like irradiation (IIR) in which the 8 Gy was delivered intermittently over a period of 40 minutes. The ability of glioma cells to migrate into a matrigel matrix was evaluated on days 1-8 from irradiation. Irradiation with CK-driven IIR significantly increased the invasion potential of U87 cells in a matrigel-based assay. In contrast to CIR, IIR was associated with increased levels of TGF-β at four days (Real time PCR), β1-integrin at 4-5 days (real-time PCR and western blot) and no elevation in phosphorylated AKT at days 4 and 5 (western blot). Our data suggests that glioma cell invasion as well as elevations of TGF-β and β1-integrin are associated with IIR and not CIR.

Expression of the new CXCL12 receptor, CXCR7, in gliomas

Gliomas are very invasive brain tumors with poor prognosis and therefore any attempt to limit tumor cell dissemination in the brain is expected to improve glioma treatment. The recent deorphanization of CXCR7 as additional receptor for CXCL12 and CXCL11 has raised key issues on its interaction with the CXCL12/CXCR4 axis as a mechanism to modulate glioma cell migration. In this work we investigated protein and mRNA expression of the two chemokines CXCL12 and CXCL11, together with their receptors CXCR4 and CXCR7 in human glioma specimens and cell lines by immunohistochemistry, flow cytometry and quantitative real-time PCR. The main purpose of this study was to find out whether and at what extent CXCR4 and CXCR7 are differentially expressed in glioma cells. In human glioma specimens the levels of CXCL11 and CXCR4 mRNA were significantly higher in glioblastomas compared to non-tumor controls or low grade gliomas, whilst no difference was found for CXCL12 and CXCR7 mRNA expression. In cell lines, flow cytometry and immunocytochemical experiments showed CXCR4 was mainly expressed irrespective of its membrane or intracellular localization. In contrast, a predominant intracellular localization together with a negligible membrane expression of CXCR7 was found in all cells examined. In in vitro experiments CXCR4 and CXCR7 antagonists and the silencing of CXCR4 showed complete inhibition of glioma proliferation. Our findings, in agreement with previous data, suggest that in human glioma cells the prevalent intracellular localization of CXCR7 might modulate the functionality of CXCL11/12 either acting as a scavenger for these chemokines or interfering with the signaling pathways activated by the stimulation of CXCR4.

CXCL12, CXCR4 and CXCR7 expression in brain metastases

Brain metastases occur in about 25% of patients who die of cancer. The most common sources of brain metastases in adults are lung, breast, kidney, colorectal cancer and melanoma. The chemokine/receptor system CXCL12/CXCR4 plays a key role in multiple biological functions; among these, homing of neoplastic cells from the primary site to the target and metastasis progression. Recently, an alternative CXCL12 receptor CXCR7 has been discovered. The aim of our study was to investigate the expression of CXCL12 and its receptors CXCR4 and CXCR7 by immunohistochemistry in 56 patients with metastatic brain disease from different non-CNS primary tumors and evaluate their prognostic relevance as well as that of other patient/treatment-related features on patient survival. CXCL12 showed an expression in tumor cells and in tumor vessels; CXCR7 was expressed by tumor and endothelial cells (both within the tumor and in the adjacent brain tissue), while CXCR4 showed a positivity in all samples with a nuclear pattern. Among the investigated immunohistochemical parameters, only CXCL12 expression in tumor endothelial cells showed a statistically significant correlation with shorter survival (p = 0.04 log-rank), perhaps identifying more aggressive tumors. Thus, this is the first study evaluating at the same time the expression of CXCL12 and its two receptors in a cohort of brain metastases.

Nestin, PDGFRbeta, CXCL12 and VEGF in glioma patients: different profiles of (pro-angiogenic) molecule expression are related with tumor grade and may provide prognostic information

Angiogenesis is a key event in the natural progression of gliomas. Nestin, a marker for multipotential neuroepithelial stem cells, is detected in neuroepithelial tumors and in proliferating endothelial cells (ECs) and is involved in the early stages of lineage commitment, proliferation and differentiation. Nestin expression is correlated with proangiogenic chemokines (CXCL12 and its receptor CXCR4) and growth factors (VEGF, PDGF-B and its receptor PDGFRbeta). VEGF expression upregulates CXCR4 on endothelial cells, binding the chemokine SDF1/CXCL12 (Stromal Derived Factor) that has a role on angiogenesis and chemotaxis of endothelial cells; PDGF (platelet-derived growth factor) and PDGFRbeta are also crucial by increasing the expression of VEGF. We performed a retrospective study on the presence and role of nestin-expressing cells in 102 patients with glioma, relating the findings to VEGF, CXCL12, PDGFRbeta expression and to clinical outcome (time to tumor progression-TTP and survival time-ST). Our results suggest that in gliomas the detection of proliferating ECs expressing nestin correlates to histological malignancy grade and clinical outcome. Also, the expression of CXCL12 in low-grade gliomas was the only factor associated with a significantly shorter TTP, suggesting a role of this chemokine in angiogenic shift and/or disease progression.

Valproic acid increases the in vitro effects of nitrosureas on human glioma cell lines

Valproic acid (VPA) has been recently investigated for its anticancer properties in different tumors, including malignant gliomas. The aim of the present work was to evaluate the effects of VPA, alone or in combination with other chemotherapeutic drugs, on in vitro growth of human glioma cell lines. A172, U373, U138, U87, and SW1783 were treated with VPA alone or in combination with mitoxantrone, etoposide, or 1,3-bis(2-chloroethyl)-l-nitrosourea (BCNU). The effects of treatments on cell growth were assessed with crystal violet staining and analyzed using the combination index (CI). The percentage of apoptotic cells and the DNA content for cell cycle phases detection were also investigated by flow cytometry. Despite a certain variability, glioma cell lines were rather resistant to the drugs tested. Addition of VPA decreased the IC50 of the chemotherapeutic agents in all cell lines tested. This effect was more evident with BCNU. The synergic effect of the association of VPA and BCNU was related to an increased block of cell cycle with accumulation in S-G2/M phases of cell cycle rather than an increased programmed cell death. In our experimental model, VPA showed anticancer properties per se on human glioma cell lines and our data support the hypothesis that, if used in association with conventional chemotherapy, it might improve the effects of single chemotherapeutic agents.

Human adult skeletal muscle stem cells differentiate into cardiomyocyte phenotype in vitro

Cell transplantation to repair or regenerate injured myocardium is a new frontier in the treatment of cardiovascular disease. Most studies on stem cell transplantation therapy in both experimental heart infarct and in phase-I human clinical trials have focused on the use of undifferentiated stem cells. Based on our previous observations demonstrating the presence of multipotent progenitor cells in human adult skeletal muscle, in this study we investigated the capacity of these progenitors to differentiate into cardiomyocytes. Here we show an efficient protocol for the cardiomyogenic differentiation of human adult skeletal muscle stem cells in vitro. We found that treatment with Retinoic Acid directed cardiomyogenic differentiation of skeletal muscle stem cells in vitro. After Retinoic Acid treatment, cells expressed cardiomyocyte markers and acquired spontaneous contraction. Functional assays exhibited cardiac-like response to increased extracellular calcium. When cocultured with mouse cardiomyocytes, Retinoic Acid-treated skeletal muscle stem cells expressed connexin43 and when transplanted into ischemic heart were detectable even 5 weeks after injection. Based on these results, we can conclude that human adult skeletal muscle stem cells, if opportunely treated, can transdifferentiate into cells of cardiac lineage and once injected into infarcted heart can integrate, survive in cardiac tissue and improve the cardiac function.

Glioblastoma-derived tumorospheres identify a population of tumor stem-like cells with angiogenic potential and enhanced multidrug resistance phenotype

We investigated in vitro the properties of selected populations of cancer stem-like cells defined as tumorospheres that were obtained from human glioblastoma. We also assessed their potential and capability of differentiating into mature cells of the central nervous system. In vivo, their tumorigenicity was confirmed after transplantation into the brain of non-obese diabetic/severe combined immunodeficient (NOD-SCID) mice. The angiogenic potential of tumorospheres and glioblastoma-derived cells grown as adherent cells was revealed by evaluating the release of angiogenic factors such as vascular endothelial growth factor and CXCL12 by ELISA, as well as by rat aortic ring assay. The proliferative response of tumorospheres in the presence of CXCL12 was observed for the first time. Multidrug resistance-associated proteins 1 and 3 as well as other molecules conferring multidrug resistance were higher when compared with primary adherent cells derived from the same tumor. Finally, we obtained cells from the tumor developing after grafting that clearly expressed the putative neural stem cell marker CD133 as shown by FACS analysis and also nestin and CXCR4. The cells' positivity for glial fibrillary acidic protein was very low. Moreover these cells preserved their angiogenic potential. We conclude that human glioblastoma could contain tumor cell subsets with angiogenic and chemoresistance properties and that this chemoresistance potential is highly preserved by immature cells whereas the angiogenic potential is, to a higher extent, a property of mature cells. A better understanding of the features of these cell subsets may favor the development of more specifically targeted therapies.

Prognostic value of CXCL12 expression in 40 low-grade oligodendrogliomas and oligoastrocytomas

Both clinical and biological features have been reported as prognostic factors in low-grade gliomas. Among these, histotype, tumor size, enhancement, age and genetic pattern. Microvessel density (MVD) has been correlated to clinical outcome in astrocytomas, but its impact in oligodendrogliomas and mixed tumors is not sure. The pro-angiogenic chemokine stromal cell-derived factor (SDF-1/CXCL12) and its receptor CXC chemokine receptor 4 (CXCR4) have been described in low-grade gliomas, with a correlation between CXCL12 expression and shorter time to progression (TTP). The intermediate filament Nestin is expressed in proliferating vessels. Platelet-derived growth factor B (PDGF-B) and its receptor PDGFR-beta are also involved in angiogenesis and malignant progression in gliomas.

Expression of Drug Resistance Proteins Pgp, MRP1, MRP3, MRP5 AND GST-π in Human Glioma

Chemotherapy in glioma is poorly effective: the blood-brain barrier and intrinsic and/or acquired drug resistance of tumor cells could partly explain this lack of major effect. We investigated expression of P-glycoprotein (Pgp), multidrug resistance protein (MRP) 1, MRP3, MRP5 and glutathione-S-transferase pi (GST-pi) in malignant glioma patients. Cytofluorimetric analysis of 48 glioma specimens and 21 primary cultures showed high levels of MRP1, moderate levels of MRP5 and low levels of Pgp, GST-pi and MRP3. Immunohistochemistry (25 glioma specimens) showed expression of GST-pi (66.7% of cases), MRP1 (51.3%), MRP5 (45.8%), Pgp (34.8%) and MRP3 (29.9%) in tumor cells. Moreover, analysis of tumor samples by real time quantitative PCR showed mRNA expression of all investigated genes. Tumor vasculature, analyzed in glioma specimens and in tumor derived endothelial cells, showed expression of all investigated proteins. Non-tumor brain samples (from a patient with arteriovenous malformation and from one with epilepsy), normal human astrocytes and cultured endothelial cells were also analyzed: astrocytes and endothelial cells expressed the highest levels of the investigated proteins, mainly MRP1 and MRP5. No significant differences in proteins expression were detected between primary or recurrent gliomas, suggesting that glioma chemoresistance is mostly intrinsic. Therefore, we detected, for the first time, the presence of MRP3 and MRP5 on glioma specimens--both in tumor and endothelial cells--and we delineated an expression profile of chemoresistance proteins in glioma. The possible association of inhibitors of drug efflux pumps with chemotherapy could be investigated to improve drugs delivery into the tumor and their cytotoxic effects.

In vitro effects of topotecan and ionizing radiation on TRAIL/Apo2L-mediated apoptosis in malignant glioma

The survival of patients with malignant gliomas is still unsatisfactory despite multimodality treatment, therefore new therapeutic strategies are required. Tumor necrosis factor apoptosis related ligand (TRAIL/Apo2L), a member of the tumor necrosis factor superfamily, may induce apoptotic cell death in several tumors, but not in normal cells, upon binding with specific receptors. In the present study, the expression and function of TRAIL receptors (TRAIL-R1/DR4 and TRAIL-R2/DR5) has been investigated in five human glioma cell lines (U87, U138, U373, A172, SW1783) in ex vivo tumors and in primary cultures obtained from the tumors. Our data show that gliomas preferentially express TRAIL R2 and that treatment with topotecan, a topoisomerase I inhibitor, significantly up-regulates its expression as detected by flow cytometry and western blotting. Moreover, in most cases, treatment with topotecan resulted in an increased sensitivity to TRAIL-dependent apoptosis, although cyclohexymide had to be added to induce apoptosis. On glioma cell lines, the effects of irradiation on TRAIL receptors were also analysed. In our experimental conditions, irradiation with 2 Gy had a modest additive effect on TRAIL-dependent apoptosis and was not able to modulate TRAIL receptor expression.

Immunotherapy with bovine aortic endothelial cells in subcutaneous and intracerebral glioma models in rats: effects on survival time, tumor growth, and tumor neovascularization

High-grade gliomas are aggressive tumors of the central nervous system characterized by endothelial cell proliferation and a high degree of vascularity. Conventional antitumoral treatments (i.e., surgery, radiotherapy, and chemotherapy) do not achieve satisfactory results (median survival in glioblastoma 12-18 months). It has been suggested that immunotherapy with xenogenic endothelial cells could slow tumor growth rate in a number of tumors in a murine model, but the study did not include gliomas. In experiments performed in our laboratory, vaccination with proliferating bovine aortic endothelium increased survival time in Fischer rats inoculated intracerebrally with 9L. Immunotherapy was also able to reduce the growth of subcutaneously injected 9L gliosarcoma cells in Fischer rats and to decrease microvessel density within the tumors, in the absence of major organ toxicity. Immunoglobulins (Ig) in the sera from vaccinated rats stained bovine aortic endothelium as well as human umbilical vein endothelium in active proliferation. Moreover, immune sera from immunized rats stained microvessels of human malignant glioma specimens and vessels of intracerebrally implanted tumors. Two proteins of MW of 11 and 19 kDa were identified by Western blot as targets of Ig elicited by vaccination. A possible future development is to select peptides/proteins suitable for vaccination in humans, avoiding the biohazards connected with xenogenic whole-cell vaccination.

Effect of Association of Temozolomide With Other Chemotherapic Agents on Cell Growth Inhibition in Glioma Cell Lines

Despite progresses in surgery and treatments of malignant gliomas, prognosis of these tumors remains poor, with a median life expectancy of 12 months in glioblastomas. Chemotherapy (mostly with nitrosoureas) has been demonstrated to prolong overall survival, but the entity of this improvement is slight and disease recurrence/progression is the rule, stressing the need for multimodality treatment. In this work we investigated the effect of association of temozolomide (TMZ), an orally bioavailable alkylating agent, with three chemotherapeutic drugs, liposomal doxorubicin (DOXO), cis-platinum (CDDP). and topotecan (TP), on cell growth of A 172, U373, U138, U87, and SW1783 (all human glioma cell lines). Results indicate a synergistic effect (CI < 1) of TMZ in association with liposomal DOXO and CDDP on cell growth inhibition in most of the studied cell lines (A172, U373, U138, U87). Synergistic effect also has been obtained after treatment of A 172 and U373 with TMZ and TP in association. In conclusion, our results confirm the potential effect of association of chemotherapic drugs with different mechanisms of action in the treatment of gliomas.