Sensitization of Gastric Cancer Cells to 5-FU by MicroRNA-204 Through Targeting the TGFBR2-Mediated Epithelial to Mesenchymal Transition.

Gastric cancer (GC) is the most common gastrointestinal malignancy, causing cancer-related deaths in East Asia. MicroRNAs (miRNAs) are small non-coding RNAs aberrantly expressed in human tumors. In this study, we aim to investigate the roles of miR-204 in the epithelial to mesenchymal transition (EMT)-associated chemosensitivity. The expression of miR-204 was detected in clinical tumor samples and GC cell lines by real time PCR. Tumor cell's growth, invasion, and migration were measured by MTT assay, wound healing assay, and transwell invasion assay, respectively. Western blot method was used to detect the protein levels of indicated genes. Luciferase reporter assay was performed to validate the target gene of miR-204. The in vivo role of miR-204 was measured using a xenograft mouse model of GC. By comparing the expressions of miR-204 in human gastric tumors and their adjacent normal tissues, it was disclosed that miR-204 was significantly downregulated in gastric tumors. Moreover, miR-204 was downregulated in multiple GC cell lines compared with normal gastric epithelial cells. Overexpression of miR-204 suppressed GC cells' proliferation, invasion, and migration. It is noteworthy that 5-FU treatments induced miR-204 expression and suppressed TGF-β pathway. By establishment of 5-FU resistant GC cell line, it was revealed that miR-204 was significantly downregulated in 5-FU resistant GC cells, representing mesenchymal features with downregulation of epithelial marker, while mesenchymal markers were upregulated. We identified TGFBR2 as a direct target of miR-204 by Western blot method and luciferase assay in GC cells and tumor samples as well. In addition, overexpression of miR-204 sensitized GC cells to 5-FU in vitro. Xenograft experiments demonstrated that the combination of miR-204 and 5-FU efficiently inhibited tumor growth and improved survival rate of mice as well. Eventually, we illustrated the restoration of TGFBR2 in miR-204 overexpression GC cells, which recovered resistance to 5-FU treatments compared with miR-204 overexpression GC cells. This study describes a miRNA-based therapeutic strategy against 5-FU resistance in GC, contributing to the development of anti-chemoresistance therapeutic agents.

Li LQ ，Pan D ，Chen Q ，Zhang SW ，Xie DY ，Zheng XL ，Chen H ... -  《-》

MicroRNA-17 inhibition overcomes chemoresistance and suppresses epithelial-mesenchymal transition through a DEDD-dependent mechanism in gastric cancer.

MicroRNAs (miRNAs), a novel class of important gene-regulatory molecules, correlates with tumor growth, invasion, metastasis, and chemo resistance in gastric cancer (GC). Microarray analysis revealed that aberrant expressed microRNA-17 (miR-17) and DEDD were identified in GC. DEDD has been found to act as an endogenous suppressor of tumor growth and metastasis through epithelial-mesenchymal transition (EMT) process. However, the role of miRNA-17 (miR-17) has not been clearly evaluated in GC, thereby a series of in vitro experiments were performed in this study. The levels of miR-17 and DEDD in GC tissues from patients diagnosed with GC and in five GC cell lines (SGC-7901, MKN-45, HGC-27, BGC823, and AGS) were detected. It was found that miR-17 up-regulated and DEDD down-regulated in GC, and SGC-7901 and AGS cells were adopted for the in vitro cell experiments, in which the expression of miR-17 or DEDD was regulated by transfection. DEDD was validated to be a target gene of miR-17. Inhibition of miR-17 impaired EMT in GC cells. In addition, transwell assay and scratch test results revealed that inhibition of miR-17 hindered GC cell invasion and migration. Moreover, inhibition of miR-17 reduced resistance to cisplatin- or 5-Fu in GC cells and induced cisplatin- or 5-Fu-treated GC cell apoptosis, which evaluated by using CCK-8 and flow cytometry assays. From the short review above, the key findings emerge that inhibition of miR-17 may have tumor suppressive effects on GC and enhance its chemosensitivity by promoting DEDD, highlighting a novel target for GC therapy.

Wu DM ，Hong XW ，Wang LL ，Cui XF ，Lu J ，Chen GQ ，Zheng YL ... -  《-》

Long Non-Coding RNA RP11-789C1.1 Suppresses Epithelial to Mesenchymal Transition in Gastric Cancer Through the RP11-789C1.1/MiR-5003/E-Cadherin Axis.

Gastric cancer (GC) is a common malignancy with a global incidence that ranks fourth among all tumor types. Epithelial-to-mesenchymal transition (EMT) is a tumor biological process with a role in GC cell metastasis. Long non-coding RNAs (lncRNAs) and microRNAs possess important regulatory functions at the cellular level and in diverse pathophysiological processes. This study was conducted to investigate whether lncRNA RP11-789C1.1 regulates EMT in GC by mediating the miR-5003/E-cadherin pathway. RP11-789C1.1 and miR-5003 expression was detected in GC specimens and cell lines by quantitative real-time PCR. Western blotting and immunohistochemistry were performed to detect EMT markers in GC. Cell Counting Kit 8 assays were carried out to explore cell proliferation. Wound healing and Transwell assays were conducted to determine the migration and invasion of GC cells. To clarify the correlation between RP11-789C1.1, miR-5003, and E-cadherin, dual-luciferase reporter assays were applied. LncRNA RP11-789C1.1 was significantly down-regulated in GC patients and cell lines, along with the concomitant up-regulation of miR-5003. Silencing RP11-789C1.1 and over-expressing miR-5003 significantly promoted the tumor behavior of GC cells. Dual-luciferase reporter assays confirmed that miR-5003 was the target of both RP11-789C1.1 and E-cadherin. Furthermore, at both the mRNA and protein level, silencing RP11-789C1.1 remarkably reduced the expression of E-cadherin and promoted EMT, which were reversed by knocking down miR-5003. LncRNA RP11-789C1.1 inhibited EMT in GC through the RP11-789C1.1/miR-5003/E-cadherin axis, which could be a promising therapeutic target for GC.

Chen Z ，Wu J ，Huang W ，Peng J ，Ye J ，Yang L ，Yuan Y ，Chen C ，Zhang C ，Cai S ，He Y ，Wu S ，Song W ... -  《-》

MiR-646 inhibited cell proliferation and EMT-induced metastasis by targeting FOXK1 in gastric cancer.

Zhang P ，Tang WM ，Zhang H ，Li YQ ，Peng Y ，Wang J ，Liu GN ，Huang XT ，Zhao JJ ，Li G ，Li AM ，Bai Y ，Chen Y ，Ren YX ，Li GX ，Wang YD ，Liu SD ，Wang JD ... -  《-》

MALAT1 Modulates TGF-β1-Induced Endothelial-to-Mesenchymal Transition through Downregulation of miR-145.

Endothelial-to-mesenchymal transition (EndMT) plays significant roles under various pathological conditions including cardiovascular diseases, fibrosis, and cancer. EndMT of endothelial progenitor cells (EPCs) contributes to neointimal hyperplasia following cell therapy Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a long non-coding RNA (lncRNA) that promotes metastasis and cancer. MicroRNA-145 (miR-145) is a tumor suppressor that has been reported to inhibit SMAD3-mediated epithelial-to-mesenchymal transition (EMT) of cancer cells. In the present study, we investigated the role of MALAT1 and miR-145 in EndMT of human circulating EPCs induced by transforming growth factor beta1 (TGF-β1). Human circulating EPCs were isolated and characterized by fluorescence-activated cell sorting (FACS). Expression levels of EndMT markers were assessed by qRT-PCR and western blotting. Alpha-smooth muscle actin (α-SMA) expression was measured by cell immunofluorescence staining. The regulatory relationship between MALAT1 and miR-145 and its target genes, TGFBR2 (TGFβ receptortype II) and SMAD3 (mothers against decapentaplegic homolog 3) was analyzed using the luciferase reporter assay. We found that EndMT of EPCs induced by TGF-β1 is accompanied by increased MALAT1 expression and decreased miR-145 expression, and MALAT1 and miR-145 directly bind and reciprocally repress each other in these cells. Dual-Luciferase Reporter assay indicated that miR-145 inhibits TGF-β1-induced EndMT by directly targeting TGFBR2 and SMAD3. MALAT1 modulates TGF-β1-induced EndMT of EPCs through regulation of TGFBR2 and SMAD3 via miR-145. Thus, the MALAT1-miR-145-TGFBR2/SMAD3 signaling pathway plays a key role in TGF-β1-induced EndMT.

Xiang Y ，Zhang Y ，Tang Y ，Li Q ... -  《-》