The significant increase of miR-140-5P in papillary thyroid cancer samples

Background and objective: Epi-miRNAs as a class of miRNA target genes involved in the epigenetic pathway like DNMTs and HDACs. They can play a role as a proto-oncogene or tumor suppressor. The present study evaluates the expression pattern of miR-140-5P, as a commonly mentioned tumor suppressor that targets DNMT1 and HDAC4 genes, in papillary thyroid cancer (PTC). Methods: 32 tissue and normal tumor margins samples of PTC were collected. The relative expression of miR-140-5P, DNMT1, and HDAC4 genes were evaluated and compared between these two groups. Results: The results revealed no significant change in the relative expression of DNMT1 and HDAC4 in PTC samples. However, the expression of miR-140-5P, contrary to our hypothesis, significantly increased in the tumor group compared to the control. Conclusion: According to the common role of miR-140-5P as a tumor suppressor gene in different groups of cancer, the expression increasing of it seems not to be acceptable. However, considering the increased expression of miR-140-5P as only reason for declining this role is also not sufficient.