The resulting hypothesis is possible that the tissue-specific features of adenocarcinoma and squamous cell cancer and the positive feedback loop consists of miR-31 and its upstream and downstream may account for the diversity of miR-31 functions.
The expression of miR‑31 was significantly higher in adenocarcinoma than in the adjacent intestinal mucosa (P<0.01), whereas the expression of LOC554202 was significantly higher in the adenocarcinoma and the rectal cancer tissue regions (P<0.01).
Experiments in multiple NSCLC cell lines in vitro and A549CD133+ cells xenograft models in vivo confirmed that down regulation of miR-31 resulted in increase of A549CD133+ cells growth, whereas overexpression of miR-31 led to the inhibition of adenocarcinoma cell proliferation.
We analyzed the reciprocal expression regulation of miR-31 and SOX4 in esophageal squamous and adenocarcinoma cell lines by qRT-PCR and Western blotting using overexpression and shRNA knock-down approaches.
We confirmed miR-31 to be upregulated in lymph node-positive patients in a separate patient cohort (P = 0.009, t test), and to be expressed at higher levels in adenocarcinoma tissue than in matched normal adjacent lung tissues (P < 0.0001, paired t test).