3.1. Differential patterns of miRNs expression in MDS patients
Relative expression of miR-18a-5p, hsa-miR-21-5p, hsa-miR-34a-5p, and hsa-miR-146a-5p was analyzed using hsa-miR-30b-5p as an endogenous control because its expression did not vary in MDS patients and controls [
14]. MDS untreated patients had significantly higher levels of miR-18a (
p = 0.012), miR-21 (
p < 0.001), and miR-34a (
p = 0.019) compared to the controls (
Figure 1A–C). This increment was significantly higher in the 5-AZA treated group for miR-21 and miR-34a (
Figure 1B,C). Although miR-146a expression tends to increase in the MDS untreated patients, no significant differences were observed in the groups (
Figure 1D). Moreover, compared to the untreated patients, 5-AZA group tends to decrease the expression of the four studied miRNs. The treatment with 5-AZA, however, did not recover the expression to the levels of the control group (
Figure 1).
3.2. miRNs expression and risk factors in MDS patients
To explore if the changes observed in the miRNs profile from untreated MDS patients are conserved during the disease progression, we categorized MDS patients according to the recent WHO classification, as early stage (ES,
n = 13; <5% bone marrow blasts) and advanced stage (AS,
n = 6; >5% bone marrow blasts). Differences between both stages of the disease in the miRNs expression profile, were not detected (
Figure 2).
We next analyzed any relationship between miRNs expression and the clinical characteristics, such as IPSS-R score, cytogenetic risk, and mutational profile. For this evaluation, untreated MDS patients were divided into two groups according different categories: IPSS-R: high risk (n = 9) vs. low risk (n = 10); Cytogenetic risk: favorable (good karyotypes, n = 13) vs. unfavorable (intermediate, poor, and very poor karyotypes, n = 6); Molecular risk: high risk (presence of at least one mutation in any of high molecular risk (HMR) genes (TP53, ETV6, ASXL1, RUNX1, EZH2), n = 11) vs. low risk (absence of mutations in HMR genes, n = 8); and Mutational score (number of total mutations present in the dysplastic clone (≤2 total mutations, n = 13) vs. (>3 total mutations, n = 6??? ES QUE NO DA TOTAL DE 19).
Based on the IPSS-R prognostic stratification, we observed that the expression of miR-18a and miR-34a trend to increase in MDS patients with a high IPSS-R risk compared with those with a low risk of progression (
Figure 3A,C). miR-21 and miR-146a expression levels, however, did not differ between both groups (
Figure 3B,D).
When we analyzed miRNs expression based on cytogenetic risk, we highlighted the significant increase in miR-21 (
p = 0.01) and miR-146a (
p = 0.02) levels in the MDS group with high cytogenetic risk compared to favorable cytogenetic risk group (
Figure 3F,H). miR-18a and miR-34a levels tend to increase in the high-risk group although this increase is not significant (
Figure 3E,G).
Finally, we categorized MDS patients concerning molecular risk (high risk, presence of at least one mutation in any of high molecular risk (HMR) genes) vs. low risk (absence of mutations in HMR genes).
We observed that miR-21 and miR-34a values trend to be higher in the MDS group that present molecular risk factors than the MDS group with no-HMR mutations (
Figure 3J,K).
Also, about molecular risk, we evaluated miRNs expression between untreated MDS group based on the mutational score (number of total mutations present in the dysplastic clone, ≤2 (n = 13) vs. >3 (n = 5) total mutations). Similarly, we did not observed differences between patients with a high number of total mutations (>3 total mutations) with respect to those with low mutational score (≤2 total mutations), although miR-34a values trend to be elevated in the MDS group with high risk.
3.3. miRNs profile could be related to redox signaling and inflammation in MDS patients
In our previous work, we analyzed the oxidative stress and inflammatory markers in MDS patients versus the control group [
6]. Here we evaluated possible correlations between the miRNs expression profile, the endogenous antioxidant system, and inflammatory markers.
Firstly, we studied the relation between the following antioxidant defense molecules: the glutathione cycle, SOD, CAT, glutathione reductase (GRd), glutathione peroxidase (GPx), and the markers of oxidative damage (lipid peroxidation, LPO, and advanced oxidation protein products, AOPP), with the four miRNs expression here analyzed in MDS patients. From all analyses, only a negative correlation between miR-21 and CAT activity (
r = -0.507,
p < 0.05) was found (
Figure 4A).
Secondly, and taking into an account that in the previous study we analyzed the plasma cytokine levels (IL-1β, IL-2, IL-6, IL-8, IL-10, TNF-α, and INF-
ɣ), here we correlated these parameters with miRs relative expressions in MDS patients. The negative correlations between miR-18a and TNF-α (r 0 -0.6471, p <0.005), and between miR-146a and IL-6 levels were detected (
r = -0.472,
p < 0.05) (
Figure 4B,C).