gms | German Medical Science

Objective: Knowledge of individual time-to-recurrence (TTR) of GBM patients is critical to enable life-prolonging repeated surgery. MicroRNAs (miRNAs) are non-coding single-stranded RNA molecules of 21 to 25 nucleotides and related to numerous tumor cell functions in GBM. Extracellular vesicles (EVs) are small, stable, membrane-closed particles secreted by tumor cells. EVs encapsulate various tumor-specific molecules such as miRNAs and contribute to GBM progression. We envisage the realization of a multi-omics approach integrating miRNAs, EVs, and proteomics to enable a combined rational detection of markers associated with GBM recurrence.

Methods: Pre- and postoperative serum samples from newly diagnosed GBM patients and patients with GBM recurrence were collected from a cohort of 50 patients and subjected to proteomic and radiomic analysis in conjunction with RNASeq analysis. EVs were separated from serum samples via differential high-speed centrifugation. Isolation of miRNA was performed using the total exosome RNA and protein isolation kit and miRNA from cells and tissues were isolated using the miRNeasy tissue/cells advanced mini kit. Micro RNAs were detected using qPCR. Osteopontin protein levels were determined by ELISA.

Results: 238 different miRNAs were identified in a cohort of 50 patients (GBM WHO°IV, IDH WT) by RNASeq analysis. Interestingly, some particular miRNAs were identified as significantly expressed in overlapping groups comparing serum, EDTA, and serum-EV samples (p-value >0.05, FC-2.0). Initially, we identified four candidate miRNAs (miR-19a-3p, miR-29b-3p, miR-130a-3p and miR-181a-5p) with functional relevance in GBM. In particular, miR-181a-5p is correlated to several genes and linked to improved survival and decreased recurrence in GBM. Expression levels of miR-181a-5p positively correlate with those of MMP9 (n=21, p=0.01, r²= 0.3) and MMP14 (n=19, p=0.04, r²= 0.22) in GBM tissue samples. Osteopontin (OPN) protein, a potent inducer of tumor angiogenesis in GBM was also correlated with different miRNA expression levels, and high levels of OPN in pre-operative EDTA samples (ELISA) are linked to poor prognosis.

Conclusion: A combination of serum markers could potentially be used to monitor GBM progress and identify recurrence at an early stage in disease progression. In particular, the combination of miRNA and proteins isolated from serum EVs has a high potential to be considered as specific.