Prognostic Significance Of Deregulated MiR-1237-3p And MiR-140-3p Expression In Spinal Chordoma:A Case-control Study

Objective:To investigate the prognostic value of miR-1237-3p and miR-140-3p expression in spinal chordoma.Methods:We retrospectively determined the miRNA expression profiling of spinal chordoma using FFPE tissues by Agilent Human miRNA Microarray Kit. The nucleus pulposus cells were used as a negative control. The differentially expressed miRNAs (miR-1237-3p and miR-140-3p) according to microarray analysis was further validated by qRT-PCR assay from chordoma tissues of42spinal chordoma patients (27males and15females, aged29-76years, mean,52.93±11.50years) and nucleus pulposus cells of14patients with disc herniation as the healthy control group (8males and6females, aged24-73years, mean,49.21±13.35years). The samples were harvested intraoperatively from all the patients. The clinical data were obtained in all cases, including age, gender, tumor size, tumor location, surrounding muscle invasion and preoperative recurrence status. The42patients (32primary patients and10recurrent patients) were classified into two groups according to the overall mean expression of miR-1237-3p (0.18±0.27) and miR-140-3p (3.56±3.17). The association of miRNA expression with clinicopathologic characteristics of spinal chordoma patients was analyzed. Furthermore, we investigated the prognostic significance of miR-140-3p and miR-1237-3p by Kaplan-Meier methods with log-rank test and a Cox proportional hazard model. Patients were followed-up clinically and radiographically. Recurrence-free survival time (RFS) was defined as the time interval from surgical resection to disease relapse, which was evaluated from clinical examination and imaging. No patients received chemotherapy or radiotherapy before the surgical excision.Results: 1. The differences of sex composition and age distribution between case and control group were not statistically significant (χ2=0.229, P=0.633and t=1.005, P=0.319, respectively).2. Microarray analysis showed that182miRNAs had significantly differential expression levels in chordoma tissues compared with that in nucleus pulposus samples (Fold change≥2.0and P≤0.05), and of them,110were upregulated and72were downregulated. Meanwhile, microarray analysis revealed that miR-1237-3p and miR-140-3p were significantly deregulated in chordoma tissues as compared to that in nucleus pulposus tissues (P=0.0036, fold change=12.62and P=0.0211, fold change=19.76, respectively). These results were validated by subsequent qRT-PCR assay, which showed the positive expression of miR-1237-3p was significantly lower in chordoma tissues than that in nucleus pulposus tissues (t=-2.906, P=0.011), and inversely, the expression of miR-140-3p was significantly upregulated in chordoma tissues as compared to that in nucleus pulposus tissues (t=3.530, P=0.001).3. The deregulated expression of miR-1237-3p and miR-140-3p had significant correlation with preoperative surrounding muscle invasion. The patients with a low expression of miR-1237-3p had a significantly increased risk of the occurence of surrounding muscle invasion as compared to those with a high expression (OR=6.000,95%CI:1.472-24.454, P=0.007), and inversely, the patients with a high miR-140-3p expression had a significantly higher risk of the occurence of surrounding muscle invasion than those with a low expression (OR=3.238,95%CI:1.719-6.101, P=0.000).4. During follow-up,32patients (76.19%) had relapse. The median RFS was28.0months (range,5-72months). The Kapan-meier survival analysis revealed that the patients with preoperative surrounding muscle invasion had a significantly shorter RFS as compared to those without surrounding muscle invasion (χ2=26.917, P=0.000, log-rank test). The patients with a low miR-1237-3p expression had a significantly shorter RFS than those with a high expression (χ2=16.217, P=0.000, log-rank test), and similarly, the patients with a high miR-140-3p expression had a significantly shorter RFS than those with a low expression (χ2=31.270, P=0.000, log-rank test).5. Cox’s multivariate analysis showed that miR-1237-3p and miR-140-3p expression (HR=0.001,95%CI:0.000-0.141, P=0.006and HR=1.267,95%CI:1.055-1.522, P=0.011, respectively) and surrounding muscle invasion (HR=4.759,95%CI:1.294-17.510, P=0.019) were significantly associated with RFS of chordoma patients as independent prognostic factors.Conclusion:The deregulation of miR-1237-3p and miR-140-3p was correlated with recurrence and tumor invasion, suggesting that miR-1237-3p as well as miR-140-3p could be a new predictor for recurrence and prognosis in patients with spinal chordoma.