Abstract
BackgroundPancreatic cancer is currently one of the leading causes of cancer deaths without any effective therapies. Mir-145 has been found to be tumor-suppressive in various types of cancers. The aim of this study is to investigate the role of miR-145 in pancreatic cancer cells and explore its underlying mechanism.MethodsQuantitative real time PCR was used to determine the expression level of miR-145 and angiopoietin-2 (Ang-2) mNRA, and the expression level of Ang-2 protein was measured by western blotting. The anti-cancer activities of miR-145 were tested both in in vitro by using cell invasion and colony formation assay and in vivo by using xenograft assay. The direct action of miR-145 on Ang-2 was predicted by TargetScan and confirmed by luciferase report assay. The vascularization of xenografts were performed by immunohistochemical analysis.ResultsThe expression level of miR-145 was significantly lower and the expression levels of Ang-2 mRNA and protein was significantly higher in the more aggressive pancreatic cancer cells (MiaPaCa-2 and Panc-1) when compared to that in BxPC3 cells. Overexpression of miR-145 in the BxPC3, MiaPaCa-2 and Panc-1 cells suppressed the cell invasion and colony formation ability, and the expression level of Ang-2 protein in MiaPaCa-2 and Panc-1 cells was also suppressed after pre-miR-145 transfection. Intratumoral delivery of miR-145 inhibited the growth of pancreatic cancer xenografts and angiogenesis in vivo, and also suppressed the expression level of angiopoietin-2 protein. Luciferase report assay showed that Ang-2 is a direct target of miR-145, and down-regulation of angiopoietin-2 by treatment with Ang-2 siRNA in the BxPC3, MiaPaCa-2 and Panc-1 cells suppressed cell invasion and colony formation ability. The reverse transcription PCR results also showed that Tie1 and Tie2 were expressed in BxPC3, MiaPaCa-2 and Panc-1 cells.ConclusionMiR-145 functions as a tumor suppressor in pancreatic cancer cells by targeting Ang-2 for translation repression and thus suppresses pancreatic cancer cell invasion and growth, which suggests that restoring of miR-145 may be a potential therapeutic target for pancreatic cancer.
Highlights
Pancreatic cancer is currently one of the leading causes of cancer deaths without any effective thera‐ pies
The expression of miR‐145 is reduced in more aggressive pancreatic cancer cell lines and accompanied with increased expression of Ang‐2 To elucidate whether the expression level of miR-145 are correlated with the cell invasion ability of pancreatic cancer, three well-studied human pancreatic cancer cell lines, BxPC3, MiaPaCa-2 and Panc-1 were investigated in the present study
In vitro invasion assay results showed that MiaPaCa-2 and Panc-1 were more aggressive than BxPC3, and our qRT-PCR results demonstrated that the expression levels of miR-145 were lower in MiaPaCa-2 and Panc-1 cells when compared to that in BxPC3 cells (Fig. 1a, b)
Summary
Pancreatic cancer is currently one of the leading causes of cancer deaths without any effective thera‐ pies. Recent studies showed that tumor suppressor loci were mutated or down-regulated in human pancreatic tumors, which accelerated tumor progression and resulted in invasive and metastatic. Previous studies demonstrated the tumor suppressive role of miR-145 in caners, in which miR-145 suppressed liver and head and neck cancer cell invasion by targeting on ADAM metallopeptidase domain 17 [7, 8]. MiR145 was reported to repress pluripotency in human embryonic stem cells via regulating the expression of octamer-binding transcription factor 4, sex determining region Y-box 2 and Kruppel-like factor 4 [9]. Khan et al [16] reported that miR-145 targeted Mucin 13, cell surface associated to suppress growth and invasion of pancreatic cancer cells
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