Regulatory role of PTEN and microRNA-141 in papillary thyroid cancer

Abstract

The aim of this study was to investigate the expression of microRNA (miR)-141 in lymphatic fluid, lymph node and tumor tissues of patients with papillary thyroid cancers (PTC), and its regulating mechanism on tumor infiltration and invasion. A total of 35 patients with PTC were included in this study: 23 cases with lymph node metastasis and 12 cases with no metastasis. Quantitative real-time polymerase chain reaction was performed to detect the expression of miR-141 and PTEN mRNA. PTEN protein expressions in lymph nodes and tumor tissues were detected by Western blot analysis, and the PTEN level in lymphatic fluid was detected by enzyme-linked immunosorbent assay. Bioinformatics prediction analysis and dual luciferase reporter assay were also performed. Compared with the normal adjacent control tissues, the expression levels of PTEN were significantly down-regulated, whereas the miR-141 expression level was significantly up-regulated in the papillary thyroid tumor tissues. Compared with the patients with lymph node metastasis, the expression levels of PTEN in the papillary thyroid tumor tissues, lymph nodes and lymphatic samples were even lower in the patients without lymph node metastasis. Bioinformatics prediction analysis and dual luciferase reporter assay showed that miR-141 directly targeted PTEN 3’-untranslated region. Down-regulated expression of PTEN in tumor tissues, lymph nodes and lymphatic fluid of PTC patients might be related to the up-regulated miR-141 expression. MiRNA-141 may regulate the infiltration, invasion and lymph node metastasis of PTC via regulating PTEN.