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The emergence of therapies such as CAR-T has created a need for reliable, validated methods for detecting EGFRvIII in patient tumor cells. Particularly so since previous studies have already suggested that some anti-EGFRvIII antibodies may be non-specific. The present paper evaluates the use of the L8A4 antibody in the immunohistochemical (IHC) and immunocytochemical (ICC) detection of EGFRvIII in 30 glioblastoma specimens, and compares it with other methods such as RT-PCR, MLPA, and FISH. The results indicate that Real-time PCR appears to be a very specific and sensitive method of EGFRvIII detection. ICC analysis with L8A4 also appears specific but requires cell culture. IHC analyses of EGFRvIII returned a number of false positives when using L8A4. Due to the growing need for an effective diagnostic tool before starting immunotherapy methods, such as the CAR-T anti-EGFRvIII or SynNotch CAR-T recognizing EGFRvIII, it is necessary to identify a more reliable and simple method of EGFRvIII detection or improve the specificity of the anti-EGFRvIII antibody, until then, immunocytochemistry may temporarily replace immunohistochemistry., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

The number of glioblastoma (GB) cases is increasing every year, and the currently available therapies remain ineffective. A prospective antigen for GB therapy is EGFRvIII, an EGFR deletion mutant containing a unique epitope that is recognized by the L8A4 antibody used in CAR-T (chimeric antigen receptor T cell) therapy. In this study, we observed that the concomitant use of L8A4 with particular tyrosine kinase inhibitors (TKIs) does not impede the interaction between L8A4 and EGFRvIII; moreover, in this case, the stabilization of formed dimers results in increased epitope display. Unlike in wild-type EGFR, a free cysteine at position 16 (C16) is exposed in the extracellular structure of EGFRvIII monomers, leading to covalent dimer formation in the region of L8A4-EGFRvIII mutual interaction. Following in silico analysis of cysteines possibly involved in covalent homodimerization, we prepared constructs containing cysteine-serine substitutions of EGFRvIII in adjacent regions. We found that the extracellular part of EGFRvIII possesses plasticity in the formation of disulfide bridges within EGFRvIII monomers and dimers due to the engagement of cysteines other than C16. Our results suggest that the EGFRvIII-specific L8A4 antibody recognizes both EGFRvIII monomers and covalent dimers, regardless of the cysteine bridging structure. To summarize, immunotherapy based on the L8A4 antibody, including CAR-T combined with TKIs, can potentially increase the chances of success in anti-GB therapy.

Background: The biological role of EGFRvIII (epidermal growth factor receptor variant three) remains unclear., Methods: Three glioblastoma DK-MG sublines were tested with EGF (epidermal growth factor) and TGFβ (transforming growth factor β). Sublines were characterized by an increased percentage of EGFRvIII-positive cells and doubling time (DK-MG low to DK-MG extra-high ), number of amplicons, and EGFRvIII mRNA expression. The influence of the growth factors on primary EGFRvIII positive glioblastomas was assessed., Results: The overexpression of exoEGFRvIII in DK-MG high did not convert them into DK-MG extra-high , and this overexpression did not change DK-MG low to DK-MG high ; however, the overexpression of RAS G12V increased the proliferation of DK-MG low . Moreover, the highest EGFRvIII phosphorylation in DK-MG extra-high did not cause relevant AKT (known as protein kinase B) and ERK (extracellular signal-regulated kinase) activation. Further analyses indicate that TGFβ is able to induce apoptosis of DK-MG high cells. This subline was able to convert to DK-MG extra-high , which appeared resistant to this proapoptotic effect. EGF acted as a pro-survival factor and stimulated proliferation; however, simultaneous senescence induction in DK-MG extra-high cells was ambiguous. Primary EGFRvIII positive (and SOX2 (SRY-Box Transcription Factor 2) positive or SOX2 negative) glioblastoma cells differentially responded to EGF and TGFβ., Conclusions: The roles of TGFβ and EGF in the EGFRvIII context remain unclear. EGFRvIII appears as a weak oncogene and not a marker of GSC (glioma stem cells). Hence, it may not be a proper target for CAR-T (chimeric antigen receptor T cells).

Background: Glioblastoma (GB) is considered one of the most lethal tumors. Extensive research at the molecular level may enable to gain more profound insight into its biology and thus, facilitate development and testing of new therapeutic approaches. Unfortunately, stable glioblastoma cell lines do not reflect highly heterogeneous nature of this tumor, while its primary cultures are difficult to maintain in vitro. We previously reported that senescence is one of the major mechanisms responsible for primary GB cells stabilization failure, to a lesser extent accompanied by apoptosis and mitotic catastrophe-related cell death., Methods: We made an attempt to circumvent difficulties with glioblastoma primary cultures by testing 3 different approaches aimed to prolong their in vitro maintenance, on a model of 10 patient-derived tumor specimens., Results: Two out of ten analyzed GB specimens were successfully stabilized, regardless of culture approach applied. Importantly, cells transduced with immortalizing factors or cultured in neural stem cell-like conditions were still undergoing senescence/apoptosis. Sequential in vivo/in vitro cultivation turned out to be the most effective, however, it only enabled to propagate cells with preserved molecular profile up to 3 rd mice transfer. Nevertheless, it was the only method that impeded these phenomena long enough to provide sufficient amount of material for in vitro/in vivo targeted analyses. Interestingly, our data additionally demonstrated that some subpopulations of several stabilized GB cell lines undergo idiopathic senescence, however, it is counterbalanced by simultaneous proliferation of other cell subpopulations., Conclusions: In the majority of primary glioma cultures, there has to be an imbalance towards apoptosis and senescence, following few weeks of rapid proliferation. Our results indicate that it has to be associated with the mechanisms other than maintenance of glioblastoma stem cells or dependence on proteins controlling cell cycle.

Glioblastoma, the most malignant astrocytic tumour, is associated with limited survival and thus rare metastases. We analysed a particularly interesting case - a 51-year-old male diagnosed within 2 years with primary and recurrent glioblastoma, isocitrate dehydrogenase (IDH)-wild type, as well as with numerous extra-central nervous system (CNS) metastatic foci. Genetic material obtained from primary and recurrent tumours, as well as from pulmonary metastasis was analysed and compared at a molecular level. Next generation sequencing (NGS) analysis revealed BRAFV600E mutation, detected only in 2-5% of glioblastomas, in both the primary tumour and pulmonary metastases. Importantly, this mutation provides a possible therapeutic option as it constitutes a target for clinically approved inhibitors. This case study not only demonstrates a molecular comparison of primary, recurrent and metastatic glioblastoma, but also emphasizes the need for precise molecular diagnostics, which may facilitate treatment choice, especially in tumours currently lacking efficient treatment.

Glioblastoma is the most common and malignant brain tumor, characterized by high cellular heterogeneity. About 50% of glioblastomas are positive for EGFR amplification, half of which express accompanying EGFR mutation, encoding truncated and constitutively active receptor termed EGFRvIII. Currently, no cell models suitable for development of EGFRvIII-targeting drugs exist, while the available ones lack the intratumoral heterogeneity or extrachromosomal nature of EGFRvIII.The reports regarding the biology of EGFRvIII expressed in the stable cell lines are often contradictory in observations and conclusions. In the present study, we use DK-MG cell line carrying endogenous non-modified EGFRvIII amplicons and derive a sub-line that is near depleted of amplicons, whilst remaining identical on the chromosomal level. By direct comparison of the two lines, we demonstrate positive effects of EGFRvIII on cell invasiveness and populational growth as a result of elevated cell survival but not proliferation rate. Investigation of the PI3K/Akt indicated no differences between the lines, whilst NFκB pathway was over-active in the line strongly expressing EGFRvIII, finding further supported by the effects of NFκB pathway specific inhibitors. Taken together, these results confirm the important role of EGFRvIII in intrinsic and extrinsic regulation of tumor behavior. Moreover, the proposed models are stable, making them suitable for research purposes as well as drug development process utilizing high throughput approach., Competing Interests: Authors declare that there are no conflicts of interest.

Cell line analysis is an important element of cancer research. Despite the progress in glioblastoma cell culturing, the cells isolated from the majority of specimens cannot be propagated infinitely in vitro. The aim of this study was to identify the processes responsible for the stabilization failure. Therefore, we analyzed 56 primary GB cultures, 7 of which were stabilized. Our results indicate that senescence is primarily responsible for the glioblastoma cell line stabilization failure, while mitotic catastrophe and apoptosis play a minor role. Moreover, a new technical approach allowed for a more profound analysis of the senescent cells in primary cultures, including the distinction between tumor and normal cells. In addition, we observed that glioblastoma cells in primary cultures have a varied potential to undergo spontaneous in vitro senescence, which is often higher than that of the normal cells infiltrating the tumor. Thus, this is the first report of GB cells in primary cell cultures (including both monolayer and spheroid conditions) rapidly and spontaneously becoming senescent. Intriguingly, our data also suggest that nearly half of GB cell lines have a combination of TP53 mutation and CDKN2A homozygous deletion, which are considered as mutually exclusive in glioblastoma. Moreover, recognition of the mechanisms of senescence and mitotic catastrophe in glioblastoma cells may be a step towards a potential new therapeutic approach.

Background: Epidermal growth factor receptor (EGFR) gene alterations play important roles in pathogenesis of glioblastoma. Antibodies against EGFRvIII have been recently developed. Their efficacy depends on numerous factors, including the co-existence of EGFRvIII with other genetic alterations, and especially with point mutations of EGFR., Materials and Methods: We examined 91 patients diagnosed with glioblastoma in order to determine the prevalence and mutual relationships between EGFR alterations. Real-time polymerase chain reaction (real-time PCR), fluorescent in situ hybridization (FISH), and sequencing were used to analyze prevalence of the amplification of EGFR gene, polysomy of chromosome 7, EGFRvIII mutation, and point mutations in exons 7-8 and 15 of EGFR., Results: We revealed that all these alterations can occur independently from each other. Nevertheless, the co-existence of EGFRvIII mutation and excessive copies of EGFR gene was observed in most cases (10/14). Similarly, the point mutations in exons 7-8 and 15 co-existed with an excessive number of EGFR copies in nearly all cases., Conclusion: EGFRvIII is a reliable and stable target for anti-EGFRvIII therapy.

Glioblastoma is a highly aggressive tumour of the central nervous system, characterised by poor prognosis irrespective of the applied treatment. The aim of our study was to analyse whether the molecular markers of glioblastoma (i.e. TP53 and IDH1 mutations, CDKN2A deletion, EGFR amplification, chromosome 7 polysomy and EGFRvIII expression) could be associated with distinct prognosis and/or response to the therapy. Moreover, we describe a method which allows for a reliable, as well as time- and cost-effective, screening for EGFR amplification and chromosome 7 polysomy with quantitative Real-Time PCR at DNA level. In the clinical data, only the patient's age had prognostic significance (continuous: HR = 1.04; p<0.01). At the molecular level, EGFRvIII expression was associated with a better prognosis (HR = 0.37; p = 0.04). Intriguingly, EGFR amplification was associated with a worse outcome in younger patients (HR = 3.75; p<0.01) and in patients treated with radiotherapy (HR = 2.71; p = 0.03). We did not observe any difference between the patients with the amplification treated with radiotherapy and the patients without such a treatment. Next, EGFR amplification was related to a better prognosis in combination with the homozygous CDKN2A deletion (HR = 0.12; p = 0.01), but to a poorer prognosis in combination with chromosome 7 polysomy (HR = 14.88; p = 0.01). Importantly, the results emphasise the necessity to distinguish both mechanisms of the increased EGFR gene copy number (amplification and polysomy). To conclude, although the data presented here require validation in different groups of patients, they strongly advocate the consideration of the patient's tumour molecular characteristics in the selection of the therapy.

Glioblastoma cell cultures in vitro are frequently used for investigations on the biology of tumors or new therapeutic approaches. Recent reports have emphasized the importance of cell culture type for maintenance of tumor original features. Nevertheless, the ability of GBM cells to preserve EGFR overdosage in vitro remains controversial. Our experimental approach was based on quantitative analysis of EGFR gene dosage in vitro both at DNA and mRNA level. Real-time PCR data were verified with a FISH method allowing for a distinction between EGFR amplification and polysomy 7. We demonstrated that EGFR amplification accompanied by EGFRwt overexpression was maintained in spheroids, but these phenomena were gradually lost in adherent culture. We noticed a rapid decrease of EGFR overdosage already at the initial stage of cell culture establishment. In contrast to EGFR amplification, the maintenance of polysomy 7 resulted in EGFR locus gain and stabilization even in long-term adherent culture in serum presence. Surprisingly, the EGFRwt expression pattern did not reflect the latter phenomenon and we observed no overexpression of the tested gene. Moreover, quantitative analysis demonstrated that expression of the truncated variant of receptor-EGFRvIII was preserved in GBM-derived spheroids at a level comparable to the initial tumor tissue. Our findings are especially important in the light of research using glioblastoma culture as the experimental model for testing novel EGFR-targeted therapeutics in vitro, with special emphasis on the most common mutated form of receptor-EGFRvIII.

Previously, we have reported that glioblastoma (GBM) cells can be differentiated into cells showing neuronal, glial and non-neural (mesenchymal) phenotypes. Before the differentiation the GBM cells co-expressed GFAP, CD44, Beta III tubulin, MAP2, Vimentin, Nestin and SOX-2, whereas during the exposure to a neural differentiation medium the differentiation process was arrested at the early stages and the GBM cells presented features of four phenotypes: multi-lineage, non-neural (mesenchymal), intermediate of neuronal cells and glial cells. Currently, we decided to check if changes in expression of: TH (tyrosine hydroxylase, marker of catecholaminergic cells) and GABA (neurotransmitter of GABAergic neurons) and markers of oligodendrocytic cells (O4, CNP) occur during the exposure of GBM cells to the differentiation medium. After exposure to the PDGF alpha and thyroid hormones (oligodendrocytic differentiation medium 10-30 days) features of oligodendrocytic differentiation were presented by 0.2-2.4% of analyzed cells. During the prolonged neural differentiation (GDNF, bFGF 20-30 days) only few cells showed expression of GABA. Moreover, in our cell cultures, there were not cells expressing markers of catecholaminergic neurons - TH. Our work confirmed that the neuronal differentiation of GBM was inhibited at the stage of the neuronal intermediate phenotype. Moreover, we showed that the oligodendrocytic differentiation of GBM cells is very inefficient.

Background: Although features of variable differentiation in glioblastoma cell cultures have been reported, a comparative analysis of differentiation properties of normal neural GFAP positive progenitors, and those shown by glioblastoma cells, has not been performed., Methods: Following methods were used to compare glioblastoma cells and GFAP+NNP (NHA): exposure to neural differentiation medium, exposure to adipogenic and osteogenic medium, western blot analysis, immunocytochemistry, single cell assay, BrdU incorporation assay. To characterize glioblastoma cells EGFR amplification analysis, LOH/MSI analysis, and P53 nucleotide sequence analysis were performed., Results: In vitro differentiation of cancer cells derived from eight glioblastomas was compared with GFAP-positive normal neural progenitors (GFAP+NNP). Prior to exposure to differentiation medium, both types of cells showed similar multilineage phenotype (CD44+/MAP2+/GFAP+/Vimentin+/Beta III-tubulin+/Fibronectin+) and were positive for SOX-2 and Nestin. In contrast to GFAP+NNP, an efficient differentiation arrest was observed in all cell lines isolated from glioblastomas. Nevertheless, a subpopulation of cells isolated from four glioblastomas differentiated after serum-starvation with varying efficiency into derivatives indistinguishable from the neural derivatives of GFAP+NNP. Moreover, the cells derived from a majority of glioblastomas (7 out of 8), as well as GFAP+NNP, showed features of mesenchymal differentiation when exposed to medium with serum., Conclusion: Our results showed that stable co-expression of multilineage markers by glioblastoma cells resulted from differentiation arrest. According to our data up to 95% of glioblastoma cells can present in vitro multilineage phenotype. The mesenchymal differentiation of glioblastoma cells is advanced and similar to mesenchymal differentiation of normal neural progenitors GFAP+NNP.

O(6)-methylguanine DNA methyltransferase (MGMT) reduces cytotoxicity of therapeutic or environmental alkylating agents. MGMT promoter methylation has been associated with TP53 G: C to A:T transition mutations in various types of cancers, and with poor prognosis in patients who did not receive chemotherapy. Mutations of TP53 are more frequent in secondary than in primary glioblastoma, thus the expected MGMT promoter methylation was low in primary glioblastoma. Glioblastoma patients with MGMT promoter methylation showed better response to chemotherapy based on alkylating agents and longer survival than patients without MGMT methylation. We examined 32 primary glioblastomas, treated with radiotherapy and surgery, for TP53 mutation by direct sequencing and MGMT promoter methylation by methylation-specific PCR. MGMT promoter methylation and TP53 mutations were detected in 72% and 31% of primary glioblastoma, respectively. Although not statistically significant, the frequency of TP53 G:C to A:T mutations were higher in cases with (26%) than without (11%) MGMT promoter methylation (p=0.376). MGMT promoter methylation had no impact on patient survival. Our data indicate that MGMT promoter methylation occurs frequently in primary glioblastoma, but does not lead to G:C to A:T TP53 mutations, has no independent prognostic value and is not a predictive marker unless glioblastoma patients are treated with chemotherapy.

We screened 50 glioblastomas for P53 mutations. Five glioblastomas showed heterozygous mutations, while three were putatively heterozygous. Six of these eight glioblastomas showed elimination of wild-type P53 mRNA. These results strongly suggest that some sort of mechanism(s) favouring mutated over wild-type P53 mRNA exists in glioblastoma cells with heterozygous mutations of this gene.

Glioblastoma multiforme (GBM), the most common malignant brain tumor of adults, is relatively rare in children. In a GBM affecting a 16-year-old boy, the tumor spread across the corpus callosum (butterfly glioma). This type of bilateral hemispheric growth has previously been thought to result from spread along the white matter tracts. Two samples obtained from opposite sides of the same tumor were analyzed comprehensively for loss of heterozygosity (LOH) and microsatellite instability (MSI). Amplification of EGFR and MDM2 was studied by means of multiplex polymerase chain reaction. Exons 5, 6, 7, and 8 of TP53 were screened for mutations by sequencing. In neither specimen were molecular alterations found in the EGFR, MDM2, or TP53 genes. The specimen obtained from the right hemisphere exhibited a high level of MSI and LOH in chromosome arms 5q, 9p, and 13q. The specimen from the left hemisphere exhibited LOH in chromosome arms 3p, 5q, 9p, 9q, 10p, 10q, and 13q. Here we propose four plausible hypothetical scenarios underlying the tumorigenesis of this GBM.

We described the case of an unusual, complex genetic alteration in 57 year-old male patient with glioblastoma multiforme (GBM) with short survival (6 and half months). Alterations consisted of p53 mutation, LOH 10, LOH 17, LOH 19q and EGFR amplification. LOH1p, LOH 9 and LOH 13 were negative. Immunohistochemical study did not correlate with molecular results. The overexpression of TP53 protein and RB protein was detected only in small percentage of cells and interestingly the overexpression of EGFR was present only focally. Immnunostainings for PTEN, P16, PI3-K were negative. Additionally, we observed an overexpression of IGFB2 protein. This case indicates the accumulation of molecular changes in glioblastoma multiforme in patient with short survival.

We observed three neoplasms with completely different histologies: malignant fibrous histiocytoma (MFH), atypical meningioma (AM), and glioblastoma (GB), developing in a patient with Li-Fraumeni syndrome. By using a combined molecular approach we performed molecular characterization of all three tumours. Data obtained showed an interesting molecular background of the AM and GB. AM showed TP53mutations and a 22q loss of heterozygosity (LOH). GB showed epidermal growth factor receptor (EGFR) amplification and TP53 mutations, whereas P16, PTEN, Rbwere intact in terms of LOH and/or multiplex PCR (polymerase chain reaction) analysis. Additionally, GB has a 1q LOH, which is an extremely rare alteration in glioblastomas. Identical 1q LOH was also observed in MFH.

The gene of epidermal growth factor receptor (EGFR) is often altered in human astrocytomas and its amplification, rearrangement and overexpression occur almost exclusively in high grade tumours (glioblastomas). MDM2 gene is amplified in a small proportion of glioblastomas, and MDM2 immunoreactivity has also been found in this group. However, the relation between gene amplification and protein overexpression depends on several factors. Thus, the study on mutual relationship between these events needs to be clarified. In a series of 28 glioblastomas, we analysed MDM2 and EGFR gene amplification by differential PCR and protein overexpression was evaluated by immunohistochemistry. Thirteen cases (45%) presented immunopositivity for EGFR. A significant amplification of EGFR gene (the EGFR/SOD ratio above the control value +/- 3 SD) was observed in 9 tumours among which, one revealed no EGFR-immunopositivity. Three tumours displayed the ratio +/- 2-3 SD but these tumours also presented immunoreactivity for EGFR. Two other glioblastomas, with weak EGFR-expression, showed no gene amplification. The immunohistochemical staining for MDM2 revealed strong positivity only in one case, and this tumour also presented MDM2 gene amplification. On the contrary, another tumour which showed MDM2 gene amplification showed no MDM2 immunopositivity. In conclusion, our results demonstrate that there is no strict correlation between gene amplification at the DNA level and protein overexpression.

Background: It has recently been reported by several sources that original (i.e., present in vivo) glioma cell phenotypes or genotypes cannot be maintained in vitro. For example, glioblastoma cell lines presenting EGFR amplification cannot be established.Methods and Results: IDH1 sequencing and loss of heterozygosity analysis was performed for 15 surgery samples of astrocytoma and early and late passages of cells derived from those and for 11 archival samples. We were not able to culture tumour cells presenting IDH1 mutations originating from currently proceeded 10 tumours; the same results were observed in 7 samples of archival material.Conclusion: The IDH1 mutation is expected to be almost mutually exclusive with EGFR amplification, so glioma cells with IDH1 mutations seem to represent a new group of tumour cells, which cannot be readily analysed in vitro because of their elimination. The reasons for this intriguing phenomenon should be investigated since its understanding can help to define a new therapeutic approach based on simulating in vivo conditions, responsible for tumour cells elimination in vitro. Moreover, a new model for culturing glioma cells in vitro should be designed since the current one does not provide conditions corresponding to in vivo growth. [ABSTRACT FROM AUTHOR]