Cardiovascular Events: A Challenge in JAK2-positive Myeloproliferative Neoplasms

Background: Myeloproliferative neoplasms (MPNs) are chronic blood disorders caused by clonal expansion in one or more myeloid lineages and include essential thrombocythemia (ET), polycythemia vera (PV), primary myelofibrosis (PMF) and chronic myeloid leukemia (CML). Cardiovascular events are a main challenge for patients with MPN and can lead to their death. Objective: JAK2V617F mutation is observed in Philadelphia-negative MPNs such as ET and PV, increasing the risk of cardiovascular complications in these patients. JAK2 mutation can affect cardiac arteries and veins in ET and PV, which results in thrombosis, ischemia and other cardiovascular events. JAK/STAT signaling pathway plays an important role in heart diseases. In this review, we will survey the cardiovascular events in JAK2-positive MPN patients. Method: Relevant English-language literature were searched and retrieved from PubMed search engine (1995–2017). The following keywords were used: "Cardiovascular Events", "JAK2" and "Myeloproliferative Neoplasms". Forty three articles were selected by using the key words. Results: JAK2 phosphorylates the signal transducers and activators of transcription (STAT). Various factors like angiotensin II (ANG II) and cardiotrophin-1 (CT-1) can bind their receptors on myocytes and increase the expression of angiotensinogen (Ao) gene by binding of STAT proteins to these factors in myocytes, causing different cardiovascular complications through autocrine mechanisms. Conclusion: JAK2 mutation is observed in patients with thrombosis, ischemia and other cardiovascular complications having abnormal increase in cell count even without definite clinical diagnosis of MPN. Therefore, identification of this mutation in these patients contributes to definite diagnosis of cardiovascular events. Also, cardiovascular complications in MPN patients can be prevented by targeting the factors involved in JAK/STAT signaling pathway. Keywords: Cardiovascular events, JAK2, myeloproliferative neoplasms, hematologic malignancies, myelofibrosis, platelets.