Blood disorders include a wide spectrum of blood-associated malignancies resulting from inherited or acquired defects. The ineffectiveness of existing therapies against blood disorders arises from different reasons, one of which is drug resistance, so different types of leukemia may show different responses to treatment. Leukemia occurs for a variety of genetic and acquired reasons, leading to uncontrolled proliferation in one or more cell lines. Regarding the genetic defects, oncogene signal transducer and activator of transcription (STAT) family transcription factor, especially STAT3, play an essential role in hematological disorders onset and progress upon mutations, dysfunction, or hyperactivity. Besides, microRNAs, as biological molecules, has been shown to play a dual role in either tumorigenesis and tumor suppression in various cancers. Besides, a strong association between STAT3 and miRNA has been reported. For example, miRNAs can regulate STAT3 via targeting its upstream mediators such as IL6, IL9, and JAKs or directly binding to the STAT3 gene. On the other hand, STAT3 can regulate miRNAs. In this review study, we aimed to determine the role of either microRNAs and STAT3 along with their effect on one another's activity and function in hematological malignancies.

Epigenetic, along with genetic mechanisms, is essential for natural evolution and maintenance of specific patterns of gene expression in mammalians. Global epigenetic variation is inherited somatically and unlike genetic variation, it is dynamic and reversible. They are somatically associated with known genetic variations.

Recent studies indicate the broad role of epigenetic mechanisms in the initiation and development of cancers, that they are including DNA methylation, histone modifications, nucleosomes changes, non-coding RNAs. The reversible nature of epigenetic changes has led to the emergence of novel epigenetic therapeutic approaches, so that several types of these medications have been approved by the FDA so far.

In this review, we discuss the concept of epigenetic changes in diseases, especially cancers, the role of these changes in the onset and progression of cancers and the potential of using this knowledge in designing novel therapeutic strategies.