Hypoxic microenvironments contribute to the
tumorigenesis of numerous
cancers by regulating the expression of a subset of
miRNAs called "hypoxiamiRs." However, the function and mechanism of these deregulated
miRNAs in hypoxic microenvironments within
pancreatic cancers remain undefined. This study demonstrates that miR-548an is significantly downregulated in
pancreatic cancer tissues and correlates with increased
tumor size, advanced TNM stage, distant
metastasis, and poor prognosis. Moreover, the overexpression of miR-548an significantly inhibited the proliferation and invasion of
pancreatic cancer cells in vitro and in vivo We further revealed that
hypoxia-induced factor-1α (HIF-1α) induces the downregulation of miR-548an in
pancreatic cancer cells during
hypoxia. Our co-IP and ChIP assays revealed that HIF-1α and
histone deacetylase 1 (HDAC1) form a complex and bind to the
hypoxia response elements (HRE) on the miR-548an promoter. In addition, inhibition of HDAC1 with
trichostatin A antagonizes the suppression of miR-548 by
hypoxia. Our dual
luciferase assay validated that miR-548an directly binds to the
3' untranslated region of
vimentin mRNA. The downregulation of
vimentin suppresses the proliferation and invasion of
pancreatic cancer cells in vitro and in vivo In addition,
vimentin was inversely correlated with miR-548an expression in
pancreatic cancer samples. In conclusion, our findings suggest that the HIF-1α-HDAC1 complex transcriptionally inhibits miR-548an expression during
hypoxia, resulting in the upregulation of
vimentin that facilitates the pancreatic
tumorigenesis. Mol
Cancer Ther; 15(9); 2209-19. ©2016 AACR.