Reciprocal modulation of Linc-223 and its ligand miR-125a on the basis of platelet function level

Background

Cardiovacular diseases (CVD) are the leading cause of death worldwide. Platelet play a key role in the pathophysiology of multiple CVD. LincRNAs are long non-coding RNAs transcribed from intergenic DNA segments. Some members of this class were recently associated with human disease. Linc-223 is co-transcribed together with mir-223 and was recently shown to bind to miR-125. Both miR-223 and miR-125 are highly expressed in platelets.

Purpose

In light of the capability of Linc-223 to bind to miR-125, we aimed to investigate whether their reciprocal expression levels might reflect the degree of platelet activity.

Methods

RNA was extracted using miRVANA. MiRNAs and lncRNAs were measured by means of quantitative Real Time RT-PCR.

Results

We found a significant reduction of Linc-223 levels (p<0.05) along with a significant increase in miR-125 levels (p<0.05) after initiation of any antiplatelet treatment (n=30) compared to naïve patients (n=10). Moreover, the upgrade to a higher-intensity antiplatelet treatment with ASA+ticagrelor from ASA+clopidogrel (n=30) was associated to a further down-regulation of Linc-223 (p<0.05) along with a further increase of miR-125. (p<0.05). Finally, these results were validated in a larger cohort of 300 patients from the ATLANTIS study, demonstrating significant modulation of both miR-223 and miR-125 in patients with high on-treatment platelet aggregation levels compared to antiplatelet-responsive patients.

Conclusions

We identify a reciprocal modulation of Linc-223 and miR-125, its ligand upon different levels of platelet aggregations. These results are compatible with previous evidence from patients with Acute Myeloid Leukemia, that Linc-223 might bind to and sponge miR-125, inhibiting its effect. These results suggest that plasma levels of Linc-223, miR-125 and miR-223 might be used a biomarkers of platelet finction in a clinical context, for risk stratification of patients or to assess the responsiveness to antiplatelet treatments.

Funding Acknowledgement

Type of funding source: None

miR-125a-5p Modulates Phenotypic Switch of Vascular Smooth Muscle Cells by Targeting ETS-1

MicroRNAs are key regulators of vascular smooth muscle cells (VSMCs) phenotypic switch, one of the main events responsible for bare metal in-stent restenosis after percutaneous coronary intervention. miR-125a-5p is an important modulator of differentiation, proliferation, and migration in different cell types; however, its role in VSMCs is still unknown. The aim of this study was to evaluate the role of miR-125a-5p in VSMCs phenotypic switch. Our results suggest that miR-125a-5p is highly expressed in VSMCs, but it is down-regulated after vascular injury in vivo. Its overexpression is sufficient to reduce VSMCs proliferation and migration, and it is able to promote the expression of selective VSMCs markers such as alpha smooth muscle actin, myosin heavy chain 11, and smooth muscle 22 alpha. Interestingly, miR-125a-5p directly targets ETS-1, a transcription factor implicated in cell proliferation and migration and is crucial in PDGF-BB pathway in VSMCs. Thus, miR-125a-5p in this context inhibits PDGF-BB pathway and is therefore a potential regulator of VSMCs phenotypic switch.