gms | German Medical Science

Objective: Detection of GBM recurrence is mainly based on Magnetic-Resonance-Imaging (MRI), however at a late stage, when recurrent tumors are already manifested. Thus there is a desperate need for novel methods to detect recurrent GBMs at earlier stages. In this context "liquid biopsies" represent a minimally invasive method to track potential biomarkers, which are associated with relapse. We examined differential expression patterns of various microRNAs in pre- and post-surgical blood samples of GBM patients.

Methods: From n=18 consecutive patients with first diagnosis GBM (histopathologically secured), who received either a total or subtotal resection, blood was taken one day before and five days after surgery. MicroRNAs were isolated with MirVana PARIS Kit (Ambion) and transcribed into cDNA with miScript II RT Kit (Qiagen) according to manufacturer’s instructions. Expression levels of miRNA were measured via qPCR and compared to the extent of resection based on pre- and post-surgical MRIs. Data were analyzed with the statistical program R.

Results: Out of a panel of 10 microRNAs reported to be serum markers in cancer, microRNAs 130a and 720 were reliably quantifiable. Therefore these two microRNAs were analyzed in the whole pool of 18 GBM patients, who were divided into two subgroups: patients with total resection (n=9) and patients with subtotal resection (n=9). Both microRNAs showed a distinct regulation in expression, when the pre- and post-surgical blood samples were compared. This effect was shown to be dependent on the extent of resection. While both microRNAs were found to be up regulated in post-surgical samples of patients who received a subtotal resection compared to pre-surgical samples (fold change microRNA 130a: +1.38; fold change microRNA 720: +7.22), a down regulation was observed in the cohort of patients who had a total resection (fold change microRNA 130a: -2.04; fold change microRNA 720: -1.80). A tendency could be observed for both microRNAs, but the effect was only significant for microRNA 720 (p=0.00128).

Conclusion: Biomarkers for early detection of GBM recurrence are highly demanded. Here we demonstrate the potential of two microRNAs, 130a and 720, to function as such biomarkers, which can be detected in serum samples of patients. The results provide a basis for further analysis of the expression pattern of microRNA 130a and 720 in the progression of GBM.