Silencing of p53 reduces cell migration in human Tenon's fibroblasts induced by TGF-β

Targeting long non-coding RNA PVT1/TGF-β/Smad by p53 prevents glioma progression

Glioma is a primary intracranial malignant tumor with poor prognosis, and its pathogenesis is unclear. This study discussed the impact of p53/lncRNA plasmacytoma variant translocation 1 (lncRNA PVT1)/transforming growth factor beta (TGF-β)/Smad axis on the biological characteristics of glioma. Glioma and normal tissues were collected, in which relative lncRNA PVT1 and p53 expression was assessed. Pearson’s analysis was adopted for the correlation analysis between lncRNA PVT1 and p53. Short interfering RNA (siRNA) against lncRNA PVT1 (siRNA-PVT1), siRNA-p53 or both was transfected into the glioma cells to evaluate effects of lncRNA PVT1 and p53 on cell proliferation, migration, invasion, and apoptosis. Mouse xenograft model of glioma was established to verify function of lncRNA PVT1 and p53 in vivo. Relationship among p53, lncRNA PVT1 and TGF-β/Smad was predicted and confirmed. Glioma tissues and cells showed downregulated p53 expression and increased lncRNA PVT1 expression. An adverse relationship was noted between p53 expression and lncRNA PVT1 expression. p53 was shown to be enriched in the lncRNA PVT1 promoter region and resulted in its suppression. p53 inhibited glioma cell proliferation, migration, and invasion, and induced apoptosis as well as arrested tumor growth by downregulating lncRNA PVT1. LncRNA PVT1was found to bind to TGF-β and activate TGF-β/Smad pathway, promoting progression of glioma. Consequently, p53 exerts anti-oncogenic function on glioma development by suppressing lncRNA PVT1 and subsequently inactivating TGF-β/Smad pathway.

The Dual Roles of MAGE-C2 in p53 Ubiquitination and Cell Proliferation Through E3 Ligases MDM2 and TRIM28

The tumor suppressor p53 is critical for the maintenance of genome stability and protection against tumor malignant transformation, and its homeostasis is usually regulated by ubiquitination. MDM2 is a major E3 ligase of p53 ubiquitination, and its activity is enhanced by TRIM28. TRIM28 also independently ubiquitinates p53 as an E3 ligase activated by MAGE-C2. Moreover, MAGE-C2 is highly expressed in various cancers, but the detailed mechanisms of MAGE-C2 involved in MDM2/TRIM28-mediated p53 ubiquitination remain unknown. Here, we found that MAGE-C2 directly interacts with MDM2 through its conserved MHD domain to inhibit the activity of MDM2 on p53 ubiquitination. Furthermore, TRIM28 acts as an MAGE-C2 binding partner and directly competes with MAGE-C2 for MDM2 interaction, thus releasing the inhibitory role of MAGE-C2 and promoting p53 ubiquitination. MAGE-C2 suppresses cell proliferation in TRIM28-deficient cells, but the overexpression of TRIM28 antagonizes the inhibitory role of MAGE-C2 and accumulates p53 ubiquitination to promote cell proliferation. This study clarified the molecular link of MAGE-C2 in two major E3 systems MDM2 and TRIM28 on p53 ubiquitination. Our results revealed the molecular function of how MAGE-C2 and TRIM28 contribute to p53 ubiquitination and cell proliferation, in which MAGE-C2 acts as a potential inhibitor of MDM2 and TRIM28 is a vital regulator for MAGE-C2 function in p53 protein level and cell proliferation. This work would be helpful to understand the regulation mechanism of tumor suppressor p53.

Aloin decelerates the progression of hepatocellular carcinoma through circ_0011385/miR-149-5p/WT1 axis

CircRNA/miRNA/mRNA axis has been reported to play crucial regulatory roles in multiple cancers, including hepatocellular carcinoma (HCC). In addition, recent investigations revealed that aloin exerted anti-tumor functions in HCC. However, the underlying mechanism of aloin on anti-tumor functions in HCC remained elusive. Therefore, this study aimed to investigate whether circRNA/miRNA/mRNA axis medicated the anti-tumor effect of aloin in HCC. Cell viability, invasion, apoptosis and autophagy were accessed by cell counting kit-8 (CCK-8), transwell invasion assay, flow cytometry, Western blot and immunofluorescence analysis, respectively. Expression levels of circ_0011385, miR-149-5p and WT1 mRNA were determined using qRT-PCR assay. Binding sites between miR-149-5p and circ_0011385 or WT1 were predicted in starBase database. The binding relationship among circ_0011385, miR-149-5p and WT1 were verified by dual-luciferase reporter assay and RNA immunoprecipitation. Besides, the rescue experiments were performed by co-transfection with cric_0011385 overexpression plasmid, si-cric_0011385, miR-149-5p mimic and inhibitor, WT1 pDNA and si-WT1 in HCC cells. Furthermore, tumor growth was also investigated in the xenograft mouse model. Aloin inhibited HCC proliferation and invasion as well as promoted apoptosis and autophagy both in vitro and in vivo. Besides, aloin suppressed circ_0011385 expression. Overexpressed circ_0011385 partially reversed the anti-tumor effect of aloin on HCC. In addition, it was revealed that the circ_0011385, miR-149-5p and WT1 genes were abnormally expressed in HCC. Furthermore, the binding interactions between circ_0011385, miR-149-5p and WT1 were predicted and confirmed. Moreover, the effect of circ_0011385 on the anti-tumor role of aloin in HCC was rescued by miR-149-5p mimics. MiR-149-5p regulated HCC progression via modulating WT1. Aloin suppressed cell proliferation, invasion and tumor growth and promoted apoptosis and autophagy in HCC through regulating circ_0011385/miR-149-5p/WT1 axis. Aloin may be a potential candidate drug for HCC treatment.Abbrevations: HCC: Hepatocellular carcinoma; ceRNA: competing endogenous RNA; miRNA: microRNA; MREs: miRNA response elements; WT1: Wilms' tumor 1; MMP-2: Matrix metalloproteinase; EMT: epithelial-mesenchymal transition; GADPH: glyceraldehyde 3-phosphate dehydrogenase; WT: wild type; MUT: mutant type; DMEM: dulbecco's modified eagle medium.

Dihydroartemisinin Inhibits TGF-β-Induced Fibrosis in Human Tenon Fibroblasts via Inducing Autophagy

Background

The formation of hypertrophic scars (HS) can result in the failure of glaucoma surgery, and fibrosis is known to be closely associated with the progression of HS. Dihydroartemisinin (DHA) has been reported to inhibit the progression of fibrosis; however, whether DHA can alleviate the formation of HS remains unclear.

Methods

In the present study, in order to examine the effects of DHA on the progression of HS, human Tenon's capsule fibroblasts (HTFs) were isolated from patients who underwent glaucoma surgery. In addition, Western blot analysis, microtubule associated protein 1 light chain 3 α staining and reverse transcription-quantitative PCR were performed to detect protein and mRNA expression levels in the HTFs, respectively. Cell proliferation was detected by Ki67 staining. Flow cytometry was used to examine apoptosis and reactive oxygen species (ROS) levels in the HTFs.

Results

The results revealed that TGF-β promoted the proliferation and fibrosis of HTFs; however, DHA significantly reversed the effects of TGF-β by increasing cell autophagy. In addition, DHA notably induced the apoptosis of TGF-β-stimulated HTFs by increasing the ROS levels, while these increases were partially reversed by 3-methyladenine. Furthermore, DHA notably increased the expression of microRNA (miR)-145-5p in HTFs in a dose-dependent manner.

Conclusion

The present study demonstrated that DHA inhibits the TGF-β-induced fibrosis of HTFs by inducing autophagy. These findings may aid in the development of novel agents for the prevention of the formation of HS following glaucoma surgery.