Serum levels of miR-320 family members are associated with clinical parameters and diagnosis in prostate cancer patients

Abstract

We studied the association of the serum levels of the microRNA family members miR-320a/-b/-c with clinico-pathological data to assess their applicability as diagnostic biomarker in prostate cancer (PCa) patients. The levels of miR-320a/-b/-c in 3 groups were evaluated by qRT-PCR (145 patients with PCa, 31 patients with benign prostatic hyperplasia (BPH) and 19 healthy controls). The levels of the three family members of miR-320 were directly correlated within each group (P < 0.001), but they differed significantly among the three groups (P < 0.001). The serum levels of the miR-320 family members were significantly increased in older patients compared to younger patients (≤ 66 years vs. > 66 years, P ≤ 0.001). In addition, the levels of all three miR-320 family members were significantly different in patients with low tumor stage compared with those with high tumor stage (miR-320a: P = 0.034; miR-320b: P = 0.006; miR-320c: P = 0.007) and in patients with low serum PSA compared with those with high serum PSA (≤ 4 ng vs. > 4 ng; miR-320a: P = 0.003; miR-320b: P = 0.003; miR-320c: P = 0.006). The levels of these miRNAs were inversely correlated with serum PSA levels. Detection in the serum samples of PCa patients with or without PSA relapse revealed higher levels of miR-320a/-b/-c in the group without PSA relapse before/after radical prostatectomy than in that with PCa relapse. In summary, the differences among the PCa/BPH/healthy control groups with respect to miR-320a/-b/-c levels in conjunction with higher levels in patients without a PSA relapse than in those with a relapse suggest the diagnostic potential of these miRNA-320 family members in PCa patients.

Keywords: PSA; diagnosis; miR-320 family; prostate cancer.

Figure 1. ROC analyses for miR-320 a, -b, and c in the serum of patients with PCa, patients with BPH and healthy controls

The miRNA levels of miR-320a (black), miR-320b (red) and miR-320c (blue) were compared between the groups PCa vs. BPH (A), Healthy controls vs. BPH (B) and Healthy controls vs. PCa (C).

Figure 2. Comparison of miR-320a,-b and -c serum levels for PCa patients without/with PSA relapse before and after radical prostatectomy (Halle cohort)

A comparison of miR-320a, -b and -c serum levels for PCa patients without (N = 36; A, C, E) and with PSA relapse (N = 41; B, D, F) before and after radical prostatectomy. There was a significant increase in miR-320a, -b and -c levels between samples before RPE and after RPE for the patients without PSA relapse (miR-320a: P = 0.019; miR-320b: P = 0.037 and miR-320c: P = 0.017) but not for the patients with PSA relapse (mir-320a: P = 0.177; miR-320b: P = 0.648; miR-320c: P = 0.089; all Mann Whitney U-test). Serum samples before and after the RPE originate from different PCa patients.

Figure 3. Progression profile of the levels of the miR-320 family members in the serum of PCa patients with/without PSA relapse (Innsbruck cohort)

Serum samples (each pooled from 5 or 4 patients) obtained 5 years and one year before PCa diagnosis, at diagnosis, and 3 months, 1 year and 3 years after diagnosis were analyzed for the levels of miR-320a, -b, and -c in PCa patients without (A) and with PSA relapse (B). A strong decrease in all three miR-320 family members at the time of diagnosis was observed in PCa patients without PSA relapse but not in those with PSA relapse.

Figure 4. Detailed progression profile of the levels of the miR-320 family members for PCa patients without and with PSA relapse

PCa patients without PSA relapse (A–C) All three miRNAs showed relatively high levels at 5 years and at 1 year before the diagnosis of PCa but a strong decrease at the time of PCa diagnosis. Remarkably, the previous high levels of miRNA-320 a, -b and -c were already reached three months after diagnosis and were maintained in PCa patients without PSA relapse. PCa patients with PSA relapse (D–F).

Figure 5. Kaplan-Meier analysis

The levels of miR-320b in group 1 (1st and 4th quartiles/red line) compared with group 2 (2nd and 3rd quartiles/green line) were associated with OS in younger PCa patients (≤66 years). PCa patients with a low/high miR-320b level survived only 119 months compared with the patients with an intermediate miR-320b level (mean: 149 months; P = 0.034; log-rank test).

Figure 6. Venn diagram showing the overlap and singularity of predicted target genes of miR-320a, -b and -c

The miRNA target genes were predicted using the database miRwalk2.0. A strong overlap of target genes (73%: 1319/1801) was observed for all three miRNAs.