Mir-16 and 21 Deregulation Are Linked to Anti-Apoptotic Bcl-2 Gene Expression in Polycythemia Vera

Polycythaemia vera (PV) is a clonal disorder characterized by an accumulation of normal red and white cells, platelets, and their progenitors in absence of a definable stimulus. Despite the advances in PV diagnosis its physiopathology remains not well elucidated. Apoptosis deregulation seems to contribute to disease establishment. MicroRNAs are small noncoding RNAs, post transcriptional repressors of genes by deadenilation, which play relevant roles in regulation of apoptotic machinery. Here we investigate the relation of apoptosis deregulation and apoptomirs expression in PV patients.

To quantify the apoptomirs −16, −21, −15a, −26a, 130b, 29c and let-7d expression in peripheral leukocytes and CD34⁺ hematopoietic stem cells (HSC) in Polycythemia Vera (PV) patients and to correlate with targets genes expression data.

30 PV patients, 13 men and 17 women with a mean age (ma) of 64. 7y. 30 healthy subjects, 13 males and 17 females, ma=60. 2y and 23 bone marrow donors, 14 males and 9 females, ma=32. 6y. Peripheral leukocytes were obtained by Haes-Steril method and CD34⁺ hematopoietic stem cells were enriched by using the magnetically activated cell sorting, total RNA was extracted according to Trizol^® method and High Capacity^® Kit was used to synthesize cDNA. The microRNAs and apoptosis-related genes expression quantification was performed by real time PCR. Results were given as 2^-ΔΔCt and statistical analyses were carried out by Mann-Whitney and Spearman tests. Western Blot was applied to detect Bcl-2 protein expression.

miR-16 and miR21 levels were increased in PV leukocytes (median= 3. 45 and 6. 97 respectively)) and CD34⁺ HSC (median= 3. 86 and 4. 07 respectively) in comparison to controls (control leukocytes median= 0. 483 and 0. 989 respectively) (CD34⁺ HSC median= 0. 978 and 1. 15, respectively) (p= 0. 0001 and 0. 0001 in leukocytes) and (p= 0. 0001 and 0. 0005 in CD34⁺ HSC, respectively). The Bcl-2 gene expression was decreased in PV leukocytes (m= 0.18) when compared to controls (m= 1. 03; p= 0. 019). In addition we found in CD34⁺ HSC negative correlation between miR-21 and anti-apoptotic gene Bcl-2 (r= −0. 417; p= 0. 033) and between miR16 and anti-apoptotic gene Bcl-2(r= −0. 384; p=0. 046). Bcl-2 western blot showed half expression in PV leukocytes when compared to controls.

The results indicate the apoptomirs expression is linked to apoptosis deregulation in Polycythemia Vera physiopathology.

No relevant conflicts of interest to declare.