Published online May 21, 2020. doi: 10.3748/wjg.v26.i19.2349
Peer-review started: November 18, 2019
First decision: January 19, 2020
Revised: February 20, 2010
Accepted: April 18, 2020
Article in press: April 18, 2020
Published online: May 21, 2020
Pancreatic cancer (PC) is one of the deadliest cancers worldwide. PC metastasis involves a complex set of events, including epithelial-mesenchymal transition (EMT), that increase tumor cell invasiveness. Recent evidence has shown that hypoxia is a major EMT regulator in pancreatic cancer cells and facilitates metastasis; however, the mechanisms remain elusive.
To investigate the role of miR-301a in hypoxia-induced EMT in PC cells.
Real-time PCR and Western blot analysis were used to detect the expression of miR-301a and EMT markers in PDAC cells cultured in hypoxic and normoxic conditions. Western blot analysis was used to detect the expression of EMT markers in PDAC cells with miR-301a overexpression. Wound healing assay and Transwell assay were used to detect the migration capabilities of PDAC cells with miR-301a overexpression and knockout. Luciferase assay was used to detect the miR-301a promoter and the 3’ untranslated region activity of TP63. Orthotopic PC mouse models were used to study the role of miR-301a in metastasis of PDAC cells in vivo. In situ hybridization assay was used to detect the expression of miR-301a in PDAC patient samples (adjacent paratumor and paired tumor tissues).
Hypoxic environment could directly promote the EMT of PC cells. The expression level of miR-301a was increased in a HIF2α dependent manner in hypoxia-cultured CFPAC-1 and BxPC-3 cells. Overexpression of miR-301a enhanced the hypoxia-induced EMT of PC cells, while knocking out miR-301a result in the suppression of hypoxia-induced EMT. TP63 was a direct target of miR-301a and involved in the metastatic process of PC cells. Furthermore, miR-301a upregulation facilitated PDAC distant metastasis and lymph node metastasis in vivo. Additionally, miR-301a overexpression was indicative of aggressive clinicopathological behaviors and poor prognosis.
The newly identified HIF-2α-miR301a-TP63 signaling pathway may play a crucial role in hypoxia-induced EMT in PDAC cells.
Core tip: In this study, we found that miR-301a expression was increased during the process of hypoxia-induced epithelial-mesenchymal transition (EMT) in pancreatic cancer (PC) cells. miR-301a overexpression facilitated hypoxia-induced EMT, while miR-301a knockout inhibited hypoxia-induced EMT in PC cells. The increased expression of miR-301a was transcriptionally regulated by HIF-2α. In addition, we identified a new target gene of miR-301a, namely, TP63, and confirmed that TP63 was involved in EMT and metastasis of PC cells. Collectively, our data suggest that the newly identified HIF-2α-miR301a-TP63 signaling pathway plays a crucial role in hypoxia-induced EMT in pancreatic ductal adenocarcinoma and that miR-301a may serve as a new prognostic biomarker and candidate miRNA for tumor diagnosis and treatment.