Targeting of GSK-3β by miR-214 to facilitate gastric cancer cell proliferation and decrease of cell apoptosis

miR-214 Modulates the Growth and Migration of Oral Cancer before and after Chemotherapy through Mediating ULK1

The role of miRNAs as crucial components in carcinogenesis has been well documented. However, whether and how miR-214 influences oral cancer cells' drug resistance remains to be elucidated, and its downstream targets are still under investigation. Hence, this research is aimed at determining miR-214 and ULK1 expression in oral cancer before and after chemotherapy and their correlations with cancer cell growth. Human oral normal epithelial cells and human tongue squamous cell carcinoma CAL-27 cells were cultured to detect miR-214 and ULK1 levels. It was found that before chemotherapy, miR-214 was higher, while ULK1 was underexpressed in CAL-27 cells, versus normal epithelial cells. After chemotherapy, miR-214 decreased obviously in CAL-27 cells, while ULK1 level increased significantly. In addition, autophagy-related genes (Beclin 1, mTOR, and P53) in CAL-27 cells were found to be significantly inhibited before chemotherapy and were obviously increased after chemotherapy. Moreover, to further determine the impacts of miR-214 and ULK1 on oral cancer cell growth after chemotherapy, the two were overexpressed or silenced in CAL-27 cells after transfection. We found that ULK1 could effectively decrease the activity and invasion of CAL-27 cells and increase their apoptosis level, while miR-214 could antagonize its antitumor effect. Therefore, miR-214 can be used as an early prognostic biomarker for oral cancer, and ULK1 is a new candidate therapeutic target.

Blockage of ETS homologous factor inhibits the proliferation and invasion of gastric cancer cells through the c-Met pathway

BACKGROUND

Gastric cancer (GC) is one of the most common and deadliest types of cancer worldwide due to its delayed diagnosis and high metastatic frequency, but its exact pathogenesis has not been fully elucidated. ETS homologous factor (EHF) is an important member of the ETS family and contributes to the pathogenesis of multiple malignant tumors. To date, whether EHF participates in the development of GC via the c-Met signaling pathway remains unclear.

AIM

To investigate the role and mechanism of EHF in the occurrence and development of GC.

METHODS

The expression of EHF mRNA in GC tissues and cell lines was measured by quantitative PCR. Western blotting was performed to determine the protein expression of EHF, c-Met, and its downstream signal molecules. The EHF expression in GC tissues was further detected by immunohistochemical staining. To investigate the role of EHF in GC oncogenesis, small interfering RNA (siRNA) against EHF was transfected into GC cells. The cell proliferation of GC cells was determined by Cell Counting Kit-8 and colony formation assays. Flow cytometry was performed following Annexin V/propidium iodide (PI) to identify apoptotic cells and PI staining to analyze the cell cycle. Cell migration and invasion were assessed by transwell assays.

RESULTS

The data showed that EHF was upregulated in GC tissues and cell lines in which increased expression of c-Met was also observed. Silencing of EHF by siRNA reduced the proliferation of GC cells. Inhibition of EHF induced significant apoptosis and cell cycle arrest in GC cells. Cell migration and invasion were significantly inhibited. EHF silencing led to c-Met downregulation and further blocked the Ras/c-Raf/extracellular signal-related kinase 1/2 (Erk1/2) pathway. Additionally, phosphatase and tensin homolog was upregulated and glycogen synthase kinase 3 beta was deactivated. Moreover, inactivation of signal transducer and activator of transcription 3 was detected following EHF inhibition, leading to inhibition of the epithelial-to-mesenchymal transition (EMT).

CONCLUSION

These results suggest that EHF plays a key role in cell proliferation, invasion, apoptosis, the cell cycle and EMT via the c-Met pathway. Therefore, EHF may serve as an antineoplastic target for the diagnosis and treatment of GC.

PVT1 Long Non-coding RNA in Gastrointestinal Cancer

Whole genome and transcriptome sequencing technologies have led to the identification of many long non-coding RNAs (lncRNAs) and stimulated the research of their role in health and disease. LncRNAs participate in the regulation of critical signaling pathways including cell growth, motility, apoptosis, and differentiation; and their expression has been found dysregulated in human tumors. Thus, lncRNAs have emerged as new players in the initiation, maintenance and progression of tumorigenesis. PVT1 (plasmacytoma variant translocation 1) lncRNA is located on chromosomal 8q24.21, a large locus frequently amplified in human cancers and predictive of increased cancer risk in genome-wide association studies (GWAS). Combined, colorectal and gastric adenocarcinomas are the most frequent tumor malignancies and also the leading cause of cancer-related deaths worldwide. PVT1 expression is elevated in gastrointestinal tumors and correlates with poor patient prognosis. In this review, we discuss the mechanisms of action underlying PVT1 oncogenic role in colorectal and gastric cancer such as MYC upregulation, miRNA production, competitive endogenous RNA (ceRNA) function, protein stabilization, and epigenetic regulation. We also illustrate the potential role of PVT1 as prognostic biomarker and its relationship with resistance to current chemotherapeutic treatments.

Downregulation of miRNA-214 inhibits cisplatin resistance, cell migration, and epithelial interstitial transformation in gastric cancer SGC-7901/DDP cells

BACKGROUND

Gastric cancer (GC) is one of the common tumors of the digestive system, and resistance to chemotherapy is the bottleneck that restricts the therapeutic effect of chemotherapy in GC. Therefore, it is of great significance to explore the mechanism of reversal of chemotherapy resistance.

AIM

To investigate the effect of miRNA-214 (miR-214) knockdown on cisplatin resistance, cell migration, and epithelial mesenchymal transformation (EMT) in GC SGC-7901/DDP cells, and to explore the preliminary mechanism.

METHODS

After transfection of SGC-7901/DDP cells with miR-214 inhibitor using the Lipofectamine^TM2000 method, the change of cell resistance to cisplatin was evaluated by the CCK-8 assay, cell migration was evaluated by wound healing assay, and the protein expression levels of E-cadherin (E-cad), Vimentin, N-cadherin (N-cad), NF-κB, and Bcl-2 were detected by Western blot.

RESULTS

After transfection with miR-214 inhibitor, the resistance of SGC-7901/DDP cells to cisplatin was significantly reduced (P < 0.05), and the ability of cell migration was obviously decreased (P < 0.05). The expression level of E-cad protein was significantly increased (P < 0.05), while the expression levels of Vimentin and N-cad proteins were significantly decreased (P < 0.05). Moreover, the expression levels of NF-κB and Bcl-2 protein in SGC-7901/DDP cells were significantly decreased (P < 0.05).

CONCLUSION

Down-regulation of miR-214 can reduce the resistance of SGC-7901/DDP cells to cisplatin and inhibit cell migration and EMT. This effect may be related to the down-regulation of NF-κB and Bcl-2 expression.

Inhibition of miR‑214 attenuates the migration and invasion of triple‑negative breast cancer cells

Triple‑negative breast cancer (TNBC) is a subtype of breast cancer. MicroRNA (miR)‑214 is closely associated with controlling the development of tumor cells; therefore, in the present study, the target gene and effects of miR‑214 on TNBC cells were explored. Luciferase activity was examined by luciferase reporter assay. The viability, invasion and migration of MDA‑MB‑231 TNBC cells were measured using Cell Counting kit‑8, Transwell and wound‑healing assays, respectively. The expression levels of various factors were determined using reverse transcription‑quantitative polymerase chain reaction and western blotting. The results demonstrated that the expression levels of miR‑214 were higher and the levels of α1‑antitrypsin (α1‑AT) were lower in TNBC tissues compared with in normal tissues. Subsequently, α1‑AT was revealed to be a target of miR‑214. Furthermore, inhibition of miR‑214 decreased cell viability, invasion and migration, enhanced the expression of E‑cadherin and tissue inhibitor of metalloproteinases‑2, and reduced the expression of metastatic tumour antigen 1 and matrix metalloproteinase‑2. Inhibition of miR‑214 also significantly downregulated the phosphorylation of protein kinase B (Akt) and mammalian target of rapamycin (mTOR), and markedly downregulated that of phosphoinositide 3‑kinase (PI3K); however, the expression levels of total PI3K, Akt and mTOR remained stable in all groups. Taken together, these findings indicated that α1‑AT may be a target of miR‑214. Downregulation of miR‑214 markedly suppressed the viability, migration and invasion of MDA‑MB‑231 cells, and inhibited the PI3K/Akt/mTOR pathway. These findings suggested that miR‑214 targeting α1‑AT may be a potential mechanism underlying TNBC development.

Loss of Super-Enhancer-Regulated circRNA Nfix Induces Cardiac Regeneration After Myocardial Infarction in Adult Mice

Supplemental Digital Content is available in the text.

Background:

circRNAs (circular RNAs) are emerging as powerful regulators of cardiac development and disease, but their roles in cardiac regeneration are still unknown. This study used superenhancers to distinguish key circRNAs in the regulation of cardiac regeneration and explored the mechanisms underlying circRNA functions.

Methods:

We used integrated bioinformatics analysis of RNA sequencing data and superenhancer catalogs to identify superenhancer-associated circRNAs. Quantitative polymerase chain reactions and in situ hybridization were performed to determine the circRNA expression patterns in hearts. Gain- and loss-of-function assays were conducted to detect the role of circRNAs in cardiomyocyte proliferation and cardiac repair after myocardial infarction. Chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assays were used to determine the binding of Meis1 (Meis homeobox 1) on circNfix-associated superenhancers. RNA pulldown and luciferase reporter assays were used to study circRNA interactions with proteins and miRNAs (micro RNAs).

Results:

We identified a circRNA, Nfix circRNA (circNfix), that was regulated by a superenhancer and overexpressed in the adult heart in humans, rats, and mice. The transcription factor Meis1 bound to the superenhancer at the circNfix locus, and increased its expression. In vitro and in vivo, cardiomyocyte proliferation was increased by knockdown of circNfix, whereas it was inhibited by circNfix overexpression. Moreover, circNfix downregulation promoted cardiomyocyte proliferation and angiogenesis and inhibited cardiomyocyte apoptosis after myocardial infarction, attenuating cardiac dysfunction and improving the prognosis. Mechanistically, circNfix reinforced the interaction of Ybx1 (Y-box binding protein 1) with Nedd4l (an E3 ubiquitin ligase), and induced Ybx1 degradation through ubiquitination, repressing cyclin A2 and cyclin B1 expression. In addition, circNfix acted as a sponge for miR-214 to promote Gsk3β (glycogen synthase kinase 3 β) expression and repress β-catenin activity.

Conclusions:

Loss of superenhancer-regulated circNfix promotes cardiac regenerative repair and functional recovery after myocardial infarction by suppressing Ybx1 ubiquitin-dependent degradation and increasing miR-214 activity and thus may be a promising strategy for improving the prognosis after MI.