There are several
microRNAs that have been consistently reported to be differentially expressed in
esophageal squamous cell carcinoma vs. normal squamous tissue, with prognostic associations for miR-21 (invasion, positive nodes, decreased survival), miR-143 (disease recurrence, invasion depth), and miR-375 (inversely correlated with advanced stage, distant
metastasis, poor overall survival, and disease-free survival). There is also evidence that miR-375 regulates gene expression associated with resistance to
chemotherapy. Hence,
microRNA expression assays have the potential to provide clinically relevant information about prognosis and potential response to
chemotherapy in patients with
esophageal squamous cell carcinoma. Results are inconsistent, however, for
microRNAs across different studies for esophageal
adenocarcinoma (EAC) vs. its precursor lesion
Barrett's esophagus. These inconsistencies may partly result from pathological and/or molecular heterogeneity in both
Barrett's esophagus and EAC, but may also result from differences in study designs or different choices of comparator tissues. Despite these inconsistencies, however, several
mRNA/
protein targets have been identified, the
cancer related biology of some of these targets is well understood, and there are clinico-pathological associations for some of these
mRNA targets.
MicroRNAs also have potential for use in
therapy for
esophageal cancers. The development of new delivery methods, such as minicells and autologous microvesicles, and molecular modifications such as the addition of aromatic
benzene pyridine analogs, have facilitated the exploration of the effects of therapeutic
microRNAs in vivo. These approaches are producing encouraging results, with one technology in a phase I/IIa clinical trial.