SRF expedites metastasis and modulates the epithelial to mesenchymal transition by regulating miR-199a-5p expression in human gastric cancer

Abstract

Dysregulation of transcription factors (TFs) is associated with tumor progression, but little is known about TF expression patterns in the context of gastric cancer (GC) metastasis. Using array-based profile analysis, we found that 22 TFs showed differential activities between GC cell lines with low- and high-metastatic potential. Of this group of TFs, serum response factor (SRF) was significantly upregulated in metastatic GC cells. SRF expression was frequently elevated in a panel of metastatic GC cells and tissues, and high-level expression of SRF was significantly associated with a more aggressive phenotype and poor prognosis in patients with GC. In GC cell lines, overexpression of SRF potently promoted cell migration and invasion in vitro as well as the formation of intrahepatic and pulmonary metastases in vivo, whereas loss of SRF inhibited GC cell invasion and metastasis. We also performed a microRNA microarray to screen for transcriptional targets of SRF and found that SRF transactivates miR-199a-5p and miR-199a-3p by directly binding to their promoters. We further determined that overexpression of miR-199a-5p, but not miR-199a-3p, increased GC cell invasion and metastasis. In contrast, inhibition of miR-199a-5p impaired the metastatic potential of GC cells in vitro and in vivo, and E-cadherin was identified as a direct and functional target of miR-199a-5p in GC cells. Specifically, our results showed that SRF promotes GC metastasis and the epithelial to mesenchymal transition (EMT) though miR-199a-5p-mediated downregulation of E-cadherin. The present study thus provides insight into the specific biological behavior of SRF in GC metastasis. As increased activity of the SRF/miR-199a-5p/E-cadherin pathway appears to promote GC cell EMT and metastasis, these regulators may therefore be developed as therapeutic targets or biomarkers for GC progression.

Gastric Cancer Cell Proliferation and Survival Is Enabled by a Cyclophilin B/STAT3/miR-520d-5p Signaling Feedback Loop

“…The 3 0 -UTR fragments of CypB were amplified and cloned in psiCHECK-2 (Promega) as previously described (29,30). A site-directed mutagenesis kit (Agilent Technologies) was used to mutate the miR-520d-5p-binding sites of these vectors.…”

Interaction between Wnt/β-catenin pathway and microRNAs regulates epithelial-mesenchymal transition in gastric cancer (Review)

“…APC was eventually identified as the immediate target of miR-27 that in turn facilitated Wnt/β-catenin pathway and EMT. Serum response factor (SRF) functions as a prometastatic factor in the context of stomach cancer formation, current research performed by Zhao et al (110) provided proof that miR-199a-5p is transactivated when SRF binds to CArG elements in its promoter. The authors reported that exceptional activation of miR-199a-5p leads to not only inhibition of CDH1 at posttranscriptional level but also import of β-catenin from adherens junctions to the cytoplasm and nucleus, forcefully indicating that the adjustive effect of miR-199a-5p on EMT may be based on Wnt signaling in GC.…”

MicroRNA-199a-5p inhibits cisplatin-induced drug resistance via inhibition of autophagy in osteosarcoma cells

“…Through negatively mediation of their targets, miRs have been implicated in numerous cellular processes, including cell survival, proliferation, differentiation, apoptosis and autophagy (13). miR-199a-5p has been observed to be deregulated and important in a variety of human cancers, including gastric cancer, non-small cell lung cancer, melanoma and colorectal cancer (14)(15)(16)(17)(18). In addition, miR-199a-5p also has an inhibitory effect on autophagy (19,20).…”