Differential role of microRNAs in the pathogenesis and treatment of Esophageal cancer.

Esophageal cancer (EC) is the most invasive disease associated with inclusive poor prognosis. EC usually is found as either adenocarcinoma (EAC) or squamous cell carcinomas (ESCC). ESCC forms in squamous cells and highly occurs in the upper third of the esophagus. EAC appears in glandular cells and ordinarily develops in the lower one third of the esophagus near the stomach. Barrett's esophagus (BE) is a metaplastic precursor of EAC. There is a persistent need for improving our understanding of the molecular basis of this disease. MicroRNAs (miRNAs) demonstrate an uncovered class of small, non-coding RNAs that can negatively regulate the protein coding gene, and are associated with approximately all known physiological and pathological processes, especially cancer. MiRNAs can affect cancer pathogenesis, playing a crucial role as either oncogenes or tumor suppressors. The recent emergence of observations on the role of miRNAs in cancer and their functions has induced many investigations to examine their relevance to esophageal cancer. In esophageal cancer, miRNA dysregulation plays a crucial role in cancer prognosis and in patients' responsiveness to neo-adjuvant and adjuvant therapies. In this review, the oncogenic, tumor suppressive, and drug resistance related roles of miRNAs, and their involvement in the pathogenesis and treatment of esophageal cancer were summarized.