Topcu, O. | Search bioRxiv

bioRxiv2023

Immunoreactivity against SLC3A2 in high grade gliomas displays positive correlation with glioblastoma patient survival: Potential target for glioma diagnosis and therapy

Immunity against cancer cells is at the forefront of fight against highly malignant tumors like glioblastomas (GBM). Autoantibodies and their autoantigen cooperators are one of the promising biomarkers linked to the immune responses and have been reported as having an initiative or prognostic role for certain types of paraneoplastic disorders. Nevertheless, immunoreactivity against antigens expressed in GBM are poorly studied. To date, autoantibodies were identified by pursuing targeted approaches. By contrast, in this study, we collected human GBM tissue and sera samples and by applying proteomics analysis, we determined autoantigen candidates for GBM. Subsequent immunohistochemistry and immunoprecipitation experiments revealed that a solute carrier; SLC3A2 is widely overexpressed in GBMs and therefore, immunoreactivity against SLC3A2 is present in high grade GBM, and SLC3A2 expression is altered in GBMs. No antibody interaction was detected in SLC3A2 expressors of low grade gliomas. Furthermore, autoantibody presence was correlated with prolonged survival of GBM patients. Taken together, for the first time, we reported that the SLC3A2 immunoreaction exists in high grade gliomas with a distinct GBM profile. In conclusion, our findings may open up new avenues for our understanding of glioma prognosis in the context of autoimmunity. This may eventually lead to diagnostic and therapeutic inventions that can be utilized for prevention of the disease progression.

immunology↗

bioRxiv2022

Inhibition of mutant RAS-RAF interaction by mimicking structural and dynamic properties of phosphorylated RAS

Undruggability of RAS proteins has necessitated alternative strategies for the development of effective inhibitors. In this respect, phosphorylation has recently come into prominence as this reversible post-translational modification attenuates sensitivity of RAS towards RAF. As such, in this study, we set out to unveil the impact of phosphorylation on dynamics of HRASWT and aim to invoke similar behavior in HRASG12D mutant by means of small therapeutic molecules. To this end, we performed molecular dynamics (MD) simulations using phosphorylated HRAS and showed that phosphorylation of Y32 distorted Switch I, hence the RAS/RAF interface. Consequently, we targeted Switch I in HRASG12D by means of approved therapeutic molecules and showed that the ligands enabled detachment of Switch I from the nucleotide-binding pocket. Moreover, we demonstrated that displacement of Switch I from the nucleotide-binding pocket was energetically more favorable in the presence of the ligand. Importantly, we verified computational findings in vitro where HRASG12D/RAF interaction was prevented by the ligand in HEK293T cells that expressed HRASG12D mutant protein. Therefore, these findings suggest that targeting Switch I, hence making Y32 accessible might open up new avenues in future drug discovery strategies that target mutant RAS proteins.

cancer biology↗