CtBP2 Regulates TGFβ2-Induced Epithelial-Mesenchymal Transition Through Notch Signaling Pathway in Lens Epithelial Cells

MicroRNA-1225-5p Promotes the Development of Fibrotic Cataracts via Keap1/Nrf2 Signaling

PURPOSE

Fibrotic cataracts, including anterior subcapsular cataract (ASC) as well as posterior capsule opacification (PCO), are a common vision-threatening cause worldwide. Still, little is known about the underlying mechanisms. Here, we demonstrate a miRNA-based pathway regulating the pathological fibrosis process of lens epithelium.

METHODS

Gain- and loss-of-function approaches, as well as multiple fibrosis models of the lens, were applied to validate the crucial role of two miR-1225 family members in the TGF-β2 induced PCO model of human LECs and injury-induced ASC model in mice.

RESULTS

Both miR-1225-3p and miR-1225-5p prominently stimulate the migration and EMT process of lens epithelial cells (LECs) in vitro as well as lens fibrosis in vivo. Moreover, we demonstrated that the underlying mechanism for these effects of miR-1225-5p is via directly targeting Keap1 to regulate Keap1/Nrf2 signaling. In addition, evidence showed that Keap1/Nrf2 signaling is activated in the TGF-β2 induced PCO model of human LECs and injury-induced ASC model in mice, and inhibition of the Nrf2 pathway can significantly reverse the process of LECs EMT as well as lens fibrosis.

CONCLUSIONS

These results suggest that blockade of miR-1225-5p prevents lens fibrosis via targeting Keap1 thereby inhibiting Nrf2 activation. The 'miR-1225-Keap1-Nrf2' signaling axis presumably holds therapeutic promise in the treatment of fibrotic cataracts.

C-terminal binding protein 2 promotes high-glucose-triggered cell proliferation, angiogenesis and cellular adhesion of human retinal endothelial cell line

PURPOSE

The proliferation and angiogenesis of human retinal endothelial cells (HRECs) are critical for the pathophysiology of diabetic retinopathy (DR). C-terminal binding protein 2 (CtBP2) has multiple biologic functions, but its effect on HRECs under high-glucose (HG) conditions is unclear.

METHODS

The cell viability, angiogenesis, cellular adhesion and CtBP2 expression levels of HRECs were measured following treatment with different concentrations of glucose. Small interfering CtBP2-targeting RNA, wide-type and function mutant plasmid of CtBP2 were constructed and then were transfected into HRECs to evaluate the effects of CtBP2 on cell functions of HRECs.

RESULTS

The expression of CtBP2 in HRECs was increased after HG treatment. HG treatment significantly increased cell proliferation, angiogenesis, and decreased relative gene expressions in gap junctions, tight junctions and adherens junctions. After CtBP2 was inhibited via siRNA, the changes induced by HG were partially restored. Conversely, only wild-type CtBP2 could increase cell proliferation and angiogenesis under HG condition. Mechanistically, we also found that CtBP2 exerted its functions to effect HG-induced changes via Akt signaling pathway.

CONCLUSION

This study implicates that CtBP2 promotes HG-induced cell proliferation, angiogenesis and cellular adhesion, and CtBP2 might be a potential target in the prevention of DR.

microRNA-133a exerts tumor suppressive role in oral squamous cell carcinoma through the Notch signaling pathway via downregulation of CTBP2

microRNAs (miRNAs) have been revealed to participate in some oral cancers and are proved to be effective. In the present study, we tried to explore the biological function of miR-133a in oral squamous cell carcinoma (OSCC) cells. The relationship that C-terminal-binding proteins 2 (CTBP2) was the putative target gene of miR-133a revealed from bioinformatics analysis was further was further validated by dual-luciferase reporter gene assay. In total, 40 patients with OSCC were enrolled for characterization of miR-133a, CTBP2, and Notch signaling pathway-related gene expression in clinical OSCC tissues. Low expression of miR-133a and high expression of CTBP2, Hes1, Notch-1, and Notch-3 were determined in OSCC tissues. OSCC cell lines were transfected with miR-133a inhibitor, miR-133a mimic, or shRNA targeting CTBP2, in response to which cell proliferation, migration, invasion, cell cycle, and apoptosis were evaluated. Transfection of miR-133a mimic induced apoptosis and inhibited OSCC cell proliferation, migration, and invasion and this was demonstrated to be attributable to decreased CTBP2 expression and suppression of the Notch signaling pathway. Taken together, we concluded that miR-133a acted as a tumor suppressor in OSCC through inhibition of the Notch signaling pathway via binding to CTBP2.

Transcriptional profiles along cell programming into corneal epithelial differentiation

Using the rabbit corneal epithelial cell line RCE1(5T5) as a model, we analyzed three differentiation stages, distinguished on basis to the growth state of cultured cells and after studying the expression of transcription factors such as Oct4, Pax6 and ΔNp63α, selected differentiation markers, and signaling or epigenetic markers such as Notch receptors and Prdm3. Namely, proliferative non-differentiated cells, committed cells, and cells that constitute a stratified epithelium with a limbal epithelial-like structure. RNAseq based transcriptome analysis showed that 4891 genes were differentially expressed among these stages displaying distinctive gene signatures: proliferative cells had 1278 genes as gene signature, and seem to be early epithelial progenitors with an Oct4⁺, KLF4⁺, Myc⁺, ΔNp63α⁺, ABCG2⁺, Vimentin⁺, Zeb1⁺, VANGL1⁺, Krt3^-, Krt12^- phenotype. Committed cells had a gene signature with 417 genes and displayed markers indicative of the beginning of corneal differentiation, and genes characteristic of proliferative cells; we found the possible participation of Six3 and Six4 transcription factors along this stage. The third stage matches with a stratified corneal epithelium (gene signature comprising 979 genes) and is typified by an increase in the expression of WNT10A and NOTCH 2 and 3 signaling and Cux1 transcription factor, besides Pax6, KLF4 or Sox9. The differentiated cells express about 50% of the genes that belong to the Epidermal Differentiation Complex (EDC). Analysis of the differences between corneal epithelium and epidermis could be crucial to understand the regulatory mechanisms that lead to the expression of the differentiated phenotype.

MicroRNA-184 is a key molecule responsible for the transforming growth factor-β2 -induced epithelial-mesenchymal transition in human lens epithelial-B3 cells

BACKGROUND

TGF-β2-induced epithelial-mesenchymal transition (EMT) is an important mechanism for posterior capsule opacity (PCO) in lens epithelial cells (LECs). This study aimed to investigate if MicroRNA-184 (miR-184) plays a role in the TGF-β2-induced EMT in LECs.

METHODS

Human LECs (HLE-B3 cells) were used in this study. Quantitative real-time polymerase chain reaction (PCR) (qRT-PCR) was performed to analyse miR-184 expressions in HLE-B3 treated with TGF-β2 at different concentrations (0-15 ng/mL) and different time (10 ng/mL, 0-48 hours). After transfection of miR-184 mimics or miR-184 inhibitor, cells were treated with 10 ng/mL TGF-β2 for 24 hours, and the expression levels of miR-184, E-cadherin, vimentin, zinc finger E-box binding homeobox 2 (ZEB2), α-Smooth muscle actin (α-SMA), Collagen 1 and bin3 were determined by qRT-PCR and Western blot, respectively.

RESULTS

TGF-β2 treatment significantly downregulated E-cadherin and upregulated vimentin generally in a dose-dependent and time-dependent manner. TGF-β2 treatment significantly elevated the level of miR-184 in both dose- and time-dependent manners. In addition, transfection of miR-184 inhibitor RNA significantly attenuated TGF-β2-induced downregulation of E-cadherin as well as upregulation of vimentin, ZEB2, α-SMA and Collagen 1, whereas transfection of miR-184 mimic further enhanced the effects of TGF-β2 on the expressions of these markers. Furthermore, TGF-β2 treatment significantly downregulated bin3, and transfection of miR-184 mimic and miR-184 inhibitor significantly enhanced and attenuated the inhibition effect of TGF-β2 on bin3, respectively.

CONCLUSIONS

miR-184 plays a key role in the TGF-β2-induced EMT in LECs, and bin3 may be a downstream protein.

A HGF‑derived peptide suppresses EMT in human lens epithelial cells via the TGF‑β/Smad and Akt/mTOR signaling pathways

Posterior capsule opacification (PCO) as a result of proliferation and fibrogenesis of lens epithelial cells (LECs) is the most frequent long‑term complication of modern cataract surgery. LECs may undergo epithelial‑mesenchymal transition (EMT) that resembles the morphological and molecular characteristics of PCO. A pre‑identified novel, hepatocyte growth factor (HGF)‑derived peptide H‑RN, was reported to exhibit anti‑angiogenic activity and anti‑inflammatory effects in ocular cells both in vitro and in vivo. However, the role of H‑RN in the promotion of the development of EMT in LECs is unknown. In the present study, the effects of H‑RN on the development of EMT induced by transforming growth factor (TGF)‑β in human LECs, and the possible signaling pathways participating in this process were investigated. The results showed that H‑RN promoted the expression of the EMT‑associated markers, α‑smooth muscle actin and fibronectin, whereas the expression of E‑cadherin and connexin 43 were reduced. The morphological changes typically associated with EMT seen in LECs induced by TGF‑β2 were inhibited by H‑RN, which was consistent with the effects of a TGF‑β2 inhibitor, SB431542. Smad2 and Smad3 phosphorylation induced by TGF‑β2 were reduced by H‑RN, and phosphorylation of Akt, mTOR and P70S6K induced by TGF‑β2 were also notably reduced by H‑RN in LECs. Therefore, the results of the present study showed that H‑RN treatment significantly suppressed the development of EMT induced by TGF‑β2, at least partially through the TGF‑β/Smad and Akt/mTOR signaling pathways in human LECs. The present study highlights that H‑RN, a novel HGF‑derived peptide, may be a novel therapeutic agent for prevention and treatment of PCO.

Curcumin Inhibits Proliferation and Epithelial-Mesenchymal Transition in Lens Epithelial Cells through Multiple Pathways

Background

Posterior capsule opacification (PCO), a complication of extracapsular lens extraction surgery that causes visual impairment, is characterized by aberrant proliferation and epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs). Curcumin, exerting inhibitive effects on cell proliferation and EMT in cancer, serves as a possible antidote towards PCO.

Methods

Cellular proliferation of LECs after treatment of curcumin was measured with MTT assay and flow cytometry. The transcriptional and expressional levels of proteins related to proliferation and EMT of LECs were quantified by western blotting and real-time PCR.

Results

Curcumin was found to suppress the proliferation of LECs by inducing G₂/M arrest via possible inhibition of cell cycle-related proteins including CDK1, cyclin B1, and CDC25C. It had also inactivated proliferation pathways involving ERK1/2 and Akt pathways in LECs. On the other hand, curcumin downregulated the EMT of LECs through blocking the TGF-β/Smad pathway and interfering Notch pathway which play important roles in PCO.

Conclusions

This study shows that curcumin could suppress the proliferation and EMT in LECs, and it might be a potential therapeutic protection against visual loss induced by PCO.

ROCK inhibitor modified intraocular lens as an approach for inhibiting the proliferation and migration of lens epithelial cells and posterior capsule opacification

Lens epithelial cells (LECs) in the capsule play a critical role in posterior capsule opacification (PCO) formation following cataract surgery. Cytoskeleton remodeling and the related ROCK pathway are quite important during cell migration and proliferation, but their role in LECs is still unclear. This study aimed to explore the mechanism of the ROCK pathway in the behavior of LECs and established a drug modified IOL for PCO prevention. We observed that the ROCK pathway inhibitor (Y27632) or cofilin knockdown reduced HLEC-B3 migration and proliferation. Furthermore, we revealed that cofilin could regulate the migration and proliferation of LECs through its phosphorylation. Interestingly, the capping protein CAPZA1 and ERM family also had an effect on the behavior of LECs. In addition, we established Y27632-PLGA modified IOLs, implanted them into rabbit eyes and found them to exhibit good safety and biocompatibility in vivo. Moreover, satisfying PCO prevention results were observed at 28 days post-operation. In summary, the ROCK pathway and the cytoskeleton remodeling protein regulate cell migration and proliferation, and the Y27632-PLGA modified IOL can prevent PCO formation.

The identification and characterization of the p.G91 deletion in CRYBA1 in a Chinese family with congenital cataracts

BACKGROUND

Mutations in more than 52 genes have been identified in isolated congenital cataracts, the majority of which are located in crystalline and connexin (gap junction) genes. An in-frame one amino acid deletion in the beta-crystalline gene CRYBA1 has been reported in several different Chinese, Caucasian and Iranian families of congenital cataracts. Further functional studies are needed to confirm the variant pathogenicity.

METHODS

The purpose of this study is to identify the genetic causes that contribute to congenital cataracts with esotropia and nystagmus in a Chinese family. Whole-exome sequencing was performed on samples from all five family members. The two brothers of the father and their daughters were then enrolled in the study, and 40 suspected variants were sequenced among the 9 subjects using Sanger sequencing. The mRNA and protein levels of CRYBA1 in the lens epithelium from cataract patients and normal controls were compared using quantitative polymerase chain reaction (qPCR) and Western blot analyses. The wild-type and mutated forms (p.G91del) of CRYBA1 cDNA were transfected into two types of cell lines, and the expression level of exogenous CRYBA1 was measured by Western blot analysis. The exogenous CRYBA1 proteins were visualized by immunofluorescence staining.

RESULTS

In this two-generation family, all three descendants inherited congenital cataracts with esotropia and nystagmus from the father, while the mother's lens was normal. After two rounds of sequencing, CRYBA1 (c. 269-271 del, p.G91del) was identified as the mutation responsible for the autosomal dominant congenital cataract in the Chinese family. CRYBA1 showed lower expression in cataract lenses than in control lenses. The deleted form (p.G91del) of CRYBA1 showed lower expression and was more aggregate to the cell membrane than the wild-type CRYBA1.

CONCLUSIONS

We performed molecular experiments to confirm that the p.G91del mutation in CRYBA1 results in abnormal expression and distribution of CRYBA1 protein, and this study could serve as an example of the pathogenicity of an in-frame small deletion in an inherited eye disorder.

C-terminal of E1A binding protein 1 enhances the migration of gastric epithelial cells and has a clinicopathologic significance in human gastric carcinoma

Background

Recent studies have claimed that the C-terminal of E1A binding proteins (CtBPs) influence tumorigenesis through participating in cell signal transduction in various human tumors. However, the detailed expression profiles of CtBP isoforms in human gastric cancer (GC) and the molecular mechanisms of CtBP involvement in tumor cell phenotypes warrant further investigation.

Materials and methods

The expression of CtBPs in GC cell lines and a human gastric epithelial cell line were explored via RT-qPCR and Western blotting assays. Moreover, the expression profiles of CtBPs in GC and histologically noncancerous tissues were explored by immunohistochemistry. To explore the effects of CtBP1 on the metastatic phenotype in GC, gastric epithelial cells were transfected with a eukaryotic expression plasmid to overexpress CTBP1, and the endogenous CtBP1 or JAK1 in GC cells was silenced through an RNA interference (RNAi) method. These transfections were validated via Western blotting, and the activation state of the JAK1/Stat3 signaling pathway was also explored via Western blotting. Furthermore, the malignant phenotype of GC cells was evaluated via a Cell Counting Kit-8 (CCK8) assay, colony formation assay, transwell assay, and wound-healing experiment.

Results

Our data revealed that the expression of CtBP1, but not CTBP2, was upregulated in 102 GC tissue samples compared with 98 noncancerous tissue samples, and the elevated expression level of CtBP1 was notably associated with distant metastasis. CTBP1 modulated cell migration and invasion through the JAK1/Stat3 signaling pathway in gastric epithelial cells. In addition, genetic silence of CtBP1 expression in GC cells notably constrained cell proliferation, invasion and migration abilities through inhibiting the activation of the JAK1/Stat3 pathway in GC cells.

Conclusion

Our data reveal that the knockout of CtBP1 notably constrains distant metastasis in GC through the JAK1/Stat3 pathway, suggesting that targeting CtBP1 is a practical anti-tumor approach to restrain tumor progression in GC.

C-terminal of E1A binding protein 2 promotes the malignancy of osteosarcoma cells via JAK1/Stat3 signaling

Previous studies have demonstrated that the C-terminal of E1A binding proteins (CtBPs) influences tumorigenesis by participating in cell signal transduction in various human malignancies. However, the detailed expression patterns of CtBP isoforms in human osteosarcoma (OS) and the molecular mechanisms of CtBP involvement in tumor cell phenotypes requires further investigation. In the present study, the expression patterns of CtBP2 in OS cells and tissues were explored by immunohistochemistry. Fetal osteoblast cells were transfected with a eukaryotic expression plasmid to overexpress CtBP2, and the endogenous CtBP2 in OS cells was silenced via a short hairpin RNA. These transfections were validated and the phosphorylation levels of the JAK1/Stat3 signaling pathway were explored via western blotting. Furthermore, the malignant phenotype of OS cells was evaluated via a Cell Counting Kit-8 assay, cell colony formation assay, cell migration assay and scratch wound healing assay. The results revealed that the expression of CtBP2, but not CtBP1, was upregulated in OS tissue samples and the elevated expression level of CtBP2 was notably associated with distant metastasis. CtBP2 was demonstrated to modulate cell migration and invasion via JAK1/Stat3 signaling pathway in fetal osteoblast cells. In addition, genetic silencing of CtBP2 expression in OS cells notably reduced cell migration abilities and the phosphorylation of the JAK1/Stat3 pathway. In summary, the present studies revealed that the loss of CtBP2 constrained distant metastasis through the JAK1/Stat3 pathway in OS, suggesting that targeting CtBP2 may be a practical anti-tumor approach to prevent OS tumor progression.

Anti-tumor Drug THZ1 Suppresses TGFβ2-mediated EMT in Lens Epithelial Cells via Notch and TGFβ/Smad Signaling Pathway

Selective covalent CDK7 inhibitor THZ1 is a promising potential anti-tumor drug in many kinds of cancers. Epithelial-mesenchymal Transition (EMT) is highly related to cancer initiation, development, invasion and metastasis and other pathogenesis processes. We treated cancer cell line Hela229 and three retinoblastoma cell lines so-RB50, WERI-Rb-1, Y79 with gradient concentration of THZ1, and found that THZ1 could inhibit cell viability and EMT, suggesting that THZ1 may be a promising drug for human cervical cancer and retinoblastoma treatment. Our results verified the role of THZ1 in EMT for the first time, however, the mechanism needs further study. Here we report that THZ1 suppresses the TGFβ2 induced EMT in human SRA01/04 lens epithelial cells (LECs), rabbit primary lens epithelial cells, and whole rat lens culture semi-in vivo model. RNA-sequencing and KEGG analysis revealed that the THZ1 inhibits EMT by down-regulating phosphorylate Smad2 and Notch signaling pathway. On the other hand, we found that THZ1 could strongly inhibit LECs proliferation through G2/M phase arrest as well as attenuating of MAPK, PI3K/AKT signaling pathway. Our results uncovered the function and underlying mechanism of THZ1 in regulation of EMT, which provides a new perspective of the anti-tumor effect by THZ1 and may offer a novel treatment for PCO.

MicroRNA-34a inhibits epithelial-mesenchymal transition of lens epithelial cells by targeting Notch1

Posterior capsule opacification (PCO) is a common long-term complication of modern cataract surgery. The epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) is a crucial process in the development of PCO. The purpose of this study is to investigate the role of microRNA-34a (miR-34a) in the regulation of EMT and its target gene. Human LECs were treated with TGFβ2 to induce EMT as a model for PCO. The mRNA levels of miR-34a and EMT markers were examined by real-time quantitative polymerase chain reaction (qPCR). The expression level of miR-34a was downregulated, whereas that of Notch1 was upregulated in TGFβ2-induced EMT of LECs. Overexpression of miR-34a by transfection with miR-34a inhibited EMT of LECs and reduced the expression of Notch1; while, inhibition of miR-34a upregulated the expression of both Notch1 and its ligand Jagged1 in LECs. Luciferase reporter assays revealed that Notch1 gene was direct target of miR-34a. Moreover, DAPT, a specific inhibitor of Notch signaling pathway, reversed LEC-EMT. In addition, the expression level of miR-34a was downregulated, whereas that of Notch1 was upregulated in capsular opacification from cataract samples. MiR-34a can negatively regulate EMT of LECs by targeting Notch1. Therefore, miR-34a/Notch1 could serve as a potential therapeutic approach for the treatment of PCO.

In vitro inhibition of proliferation, migration and epithelial-mesenchymal transition of human lens epithelial cells by fasudil

AIM

To study the potential role of fasudil as a treatment for posterior capsular opacification (PCO) of the human crystalline lens.

METHODS

Human lens epithelial cells (HLECs; line SRA01/04) was exposed to transforming growth factor-β2 (TGF-β2) to induce the process of epithelial-mesenchymal transition (EMT). Fasudil was applied to the cell samples. Its effect on overall HLECs proliferation and migration was studied, as was its influence on EMT induction by TGF-β2 using cell migration assay, MTT colorimetric assay and Western blot assay.

RESULTS

Fasudil inhibited the proliferation of SRA01/04. Its effect was time- and concentration-dependent. The migration of SRA01/04 cells was significantly reduced 24-72h after fasudil treatment, and the half maximal inhibitory concentration (IC50) was 22.37 µmol/mL at 72h. Reversal of the elongated, fibroblast-like shape changes induced by TGF-β2 in SRA01/04 cells was observed. Fasudil up-regulated the expression of Connexin43 protein and down-regulated the expression of α-SMA protein compared with the cells treated with TGF-β2. Furthermore, when exposed to fasudil, the phosphorylation of Rho-associated protein kinase (Rock) and myosin light chain (MLC) could not be activated in the cell preparations.

CONCLUSION

Fasudil suppresses the proliferation and migration of SRA01/04 cells, and inhibits the process of EMT induced by TGF-β2. These results suggest that fasudil may serve as a therapeutic agent for PCO.

Functional Role of Non-Coding RNAs during Epithelial-To-Mesenchymal Transition

Epithelial-to-mesenchymal transition (EMT) is a key biological process involved in a multitude of developmental and pathological events. It is characterized by the progressive loss of cell-to-cell contacts and actin cytoskeletal rearrangements, leading to filopodia formation and the progressive up-regulation of a mesenchymal gene expression pattern enabling cell migration. Epithelial-to-mesenchymal transition is already observed in early embryonic stages such as gastrulation, when the epiblast undergoes an EMT process and therefore leads to the formation of the third embryonic layer, the mesoderm. Epithelial-to-mesenchymal transition is pivotal in multiple embryonic processes, such as for example during cardiovascular system development, as valve primordia are formed and the cardiac jelly is progressively invaded by endocardium-derived mesenchyme or as the external cardiac cell layer is established, i.e., the epicardium and cells detached migrate into the embryonic myocardial to form the cardiac fibrous skeleton and the coronary vasculature. Strikingly, the most important biological event in which EMT is pivotal is cancer development and metastasis. Over the last years, understanding of the transcriptional regulatory networks involved in EMT has greatly advanced. Several transcriptional factors such as Snail, Slug, Twist, Zeb1 and Zeb2 have been reported to play fundamental roles in EMT, leading in most cases to transcriptional repression of cell⁻cell interacting proteins such as ZO-1 and cadherins and activation of cytoskeletal markers such as vimentin. In recent years, a fundamental role for non-coding RNAs, particularly microRNAs and more recently long non-coding RNAs, has been identified in normal tissue development and homeostasis as well as in several oncogenic processes. In this study, we will provide a state-of-the-art review of the functional roles of non-coding RNAs, particularly microRNAs, in epithelial-to-mesenchymal transition in both developmental and pathological EMT.