Cezary Tręda

Epidermal growth factor receptor variant III (EGFRvIII) is a constitutively active EGFR deletion variant found in a subset of glioblastomas (GB). Its association with stem-like tumor populations is well documented, but the outcome of EGFRvIII expression may vary with the developmental and molecular state of the recipient cell. Here, we used human induced pluripotent stem cell (iPSC)-derived, glial fibrillary acidic protein (GFAP)-negative-induced neural stem cells (iNSCs) to explore how this receptor variant affects a defined neural stem/progenitor background. EGFRvIII was introduced either constitutively by lentiviral transduction or through a doxycycline-responsive Tet-On system. Both experimental approaches were associated with remodeling of the neural stem/progenitor marker profile, with reduced SRY-box transcription factor 2 (SOX2) expression in the inducible model and significant reductions in both SOX2 and nestin in the constitutive model. Constitutive expression was also associated with increased senescence-associated β-galactosidase (SA-β-Gal) activity, while doxycycline induction produced a distinct change in cell-number dynamics at low doxycycline concentration. Thus, in this experimental setting, EGFRvIII was linked to substantial remodeling of the SOX2+/nestin+ marker profile. These observations do not define a differentiation pathway, prove cellular senescence or malignant transformation, or identify the cell of origin of EGFRvIII-positive GB. Rather, they support the view that the cellular response to EGFRvIII should be considered in relation to the specific neural-glioblastoma precursor context.

Recent years have seen rapid progress in biological treatments for genetic diseases, as well as conditions like type 1 diabetes that lack an obvious genetic component. The authors sought to explain why this progress has emerged at this particular moment. The best way to illustrate this is by showcasing a wide range of therapies targeting diverse diseases. This progress has been driven by technological advances in genetically modified CAR-T and CAR-NK cells (e.g., using CRISPR or transgenes), which have led to significant improvements in cancer therapy. A key trend now is the emergence of “off-the-shelf” approaches aimed at generating cellular therapies compatible with a range of recipients by mitigating alloreactivity and immune rejection. Different diseases impose distinct biological and logistical limitations; thus, treatment of each patient requires an appropriate strategy. Emerging advances include the modification of therapeutic cells, either ex vivo or in vivo. Current options for transgene delivery mainly comprise lipid nanoparticles (LNPs), adeno-associated virus (AAV) vectors, and lentiviral vectors. Researchers also focus on selecting suitable promoters for specific expression in selected cell types. Altogether, these advances have led to remarkable progress in treating various diseases in recent years. This publication discusses the development of biological therapies, with particular emphasis on cell and gene therapies, illustrated by viable examples across various disorders. It covers implemented solutions for several types of cancer, as well as selected hereditary diseases and syndromes, including Huntington’s disease, carbamoyl phosphate synthetase 1 (CPS1) deficiency, hemiplegia, epidermolysis bullosa, chronic granulomatous disease, and congenital deafness. Emerging applications in heart diseases and diabetes are also summarized, along with therapeutic strategies involving tRNA gene editing. Although numerous strategies exist, only the most representative, practical, and up-to-date examples are emphasized.

Cell therapy offers hope, but it also presents challenges, most particularly the limited ability of human organs and tissues to regenerate. Since many diseases are associated with irreversible pathophysiological or traumatic changes, stem cells and their derivatives are unable to secure healing. Although regenerative medicine offers chances for improvements in many diseases, such as type one diabetes and Parkinson's disease, it cannot eliminate the primary cause of many of them. While successes can be expected for diseases such as sickle cell disease, this is not the case for hereditary diseases with varied mutation types or for ciliopathies, which start in embryogenesis. In this complicated medical environment, synthetic biology offers some solutions, but their implementation will take many years. Still, positive examples such as CAR‐T therapy offer hope.

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.