Expression analysis and prognostic/predictive significance of a panel of microRNAs (miR-124a, miR-381, miR-637) in primary IDH-wildtype glioblastoma
Luca Bertero1, Giuseppe Mancuso2, Fabio Callipo2, Laura Traballi2, Paola Cassoni1, Rebecca Senetta3, Roberta
Rudà4, Jlenia Antona5, Elena Trisolini2, Renzo Boldorini2,5
1 Div. Pathology, Dept. Medical Sciences, University of Turin, Turin, Italy.
2 Div. Pathology, Dept. Health Sciences, University of Eastern Piedmont, Novara, Italy 3 Div. Pathology, Istituto di Candiolo - IRCCS, Candiolo, Italy
4 Div. Neuro-oncology, Città della Salute e della Scienza Hospital, Turin, Italy 5 Div. Pathology, Maggiore della Carità Hospital, Novara, Italy
BACKGROUND: MicroRNAs (miRNAs) are small non-coding RNA molecules regulating mRNAs translation. Significant differences in miRNAs expression have been found in glioblastoma compared to normal brain tissue. MiR-124a, miR-381 and miR-637 are involved in regulation of pathways which are commonly deregulated in glioblastoma (MAPK/ERK, WNT/β-catenin and AKT pathways, respectively).
AIM: To investigate the expression profile and prognostic/predictive role of miR-124a, miR-381 and miR-637 in primary IDH-wildtype glioblastoma.
MATERIALS AND METHODS: Inclusion criteria were: pathological diagnosis of primary IDH-wildtype glioblastoma (according to WHO 2016 criteria), partial/total surgical resection followed by at least one line of postoperative adjuvant treatment, ≥ 6-months follow-up after diagnosis, Caucasian ethnicity. Histological revision was performed independently by two pathologists to confirm diagnosis. IDH1/IDH2 status was assessed by Sanger sequencing according to standard protocols. Total RNA was extracted using miRNeasy FFPE (QIAGEN), miRNAs were amplified with TaqMan MicroRNA Assays (ThermoFisher) and RNU6B was used as endogenous control, while ten normal brain areas were selected as external controls. Relative quantification miRNA expression values (RQ) were calculated using the ΔΔCt method. X-tile plots and Stata (StataCorp LP) were used to calculate RQ cut-off values and for statistical analyses, respectively. Informed consent was obtained according to local regulations.
RESULTS: Here we present preliminary results based on 49 patients, 30 males (61%). Median age was 59 years (range 38-75), median KPS before surgery 80 (range 70-90). Partial resection was achieved in 27/49 (55%), total in 22/49 (45%). Median progression-free survival (PFS) was 9.4 months (range 3.5-26), median overall survival (OS) 16 months (range 3.5-42.7). Total resection and adjuvant treatment according to Stupp regimen were both associated with a better outcome as expected. Glioblastoma samples showed a reduced expression of all three miRNAs compared to normal brain. Significantly better PFS (9.9 vs 6.0 months, p=0.002) was found in patients with up-regulated miR-637 (RQ cut-off: 0.248), whereas OS difference was not significant (16.9 vs 15.6, p=0.161). A specific RQ range of miR-381 (RQ 0.104-0.287) was associated with better PFS (9.8 vs 7.4, p=0.0183), but not with OS (16.4 vs 15.8, p=0.782). No significant associations were found between miR-124a and outcome.
CONCLUSIONS: A better PFS was significantly associated with miR-637 up-regulation, a finding consistent with its reported inhibitory effect on the AKT pathway. Interestingly, the favorable role of miR-381 seems to be limited to a specific range of RQ comprising the cut-off value. These preliminary findings need to be assessed in a larger series and the study is ongoing.
