JNK1/β-catenin axis regulates H2O2-induced epithelial-to-mesenchymal transition in human lens epithelial cells

Oxidative Stress, Glutaredoxins, and Their Therapeutic Potential in Posterior Capsular Opacification

Posterior capsular opacification (PCO) is the most common long-term complication of cataract surgery. Traditionally, the pathogenesis of PCO involves the residual lens epithelial cells (LECs), which undergo transdifferentiation into a myofibroblast phenotype, hyperproliferation, matrix contraction, and matrix deposition. This process is driven by the marked upregulation of inflammatory and growth factors post-surgery. Recently, research on the role of redox environments has gained considerable attention. LECs, which are in direct contact with the aqueous humour after cataract surgery, are subjected to oxidative stress due to decreased levels of reduced glutathione and increased oxygen content compared to contact with the outer fibre layer of the lens before surgery. In this review, we examine the critical role of oxidative stress in PCO formation. We also focus on glutaredoxins (Grxs), which are antioxidative enzymes produced via deglutathionylation, their protective role against PCO formation, and their therapeutic potential. Furthermore, we discuss the latest advancements in PCO therapy, particularly the development of advanced antioxidative pharmacological agents, and emphasise the importance and approaches of anti-inflammatory and antioxidant treatments in PCO management. In conclusion, this review highlights the significant roles of oxidative stress in PCO, the protective effects of Grxs against PCO formation, and the potential of anti-inflammatory and antioxidant therapies in treating PCO.

Naringin activates semaphorin 3A to ameliorate TGF-β-induced endothelial-to-mesenchymal transition related to atrial fibrillation

The loss of semaphorin 3A (Sema3A), which is related to endothelial-to-mesenchymal transition (EndMT) in atrial fibrosis, is implicated in the pathogenesis of atrial fibrillation (AF). To explore the mechanisms by which EndMT affects atrial fibrosis and assess the potential of a Sema3A activator (naringin) to prevent atrial fibrosis by targeting transforming growth factor-beta (TGF-β)-induced EndMT, we used human atria, isolated human atrial endocardial endothelial cells (AEECs), and used transgenic mice expressing TGF-β specifically in cardiac tissues (TGF-β transgenic mice). We evaluated an EndMT marker (Twist), a proliferation marker (proliferating cell nuclear antigen; PCNA), and an endothelial cell (EC) marker (CD31) through triple immunohistochemistry and confirmed that both EndMT and EC proliferation contribute to atrial endocardial fibrosis during AF in TGF-β transgenic mice and AF patient tissue sections. Additionally, we investigated the impact of naringin on EndMT and EC proliferation in AEECs and atrial fibroblasts. Naringin exhibited an antiproliferative effect, to which AEECs were more responsive. Subsequently, we downregulated Sema3A in AEECs using small interfering RNA to clarify a correlation between the reduction in Sema3A and the elevation of EndMT markers. Naringin treatment induced the expression of Sema3A and a concurrent decrease in EndMT markers. Furthermore, naringin administration ameliorated AF and endocardial fibrosis in TGF-β transgenic mice by stimulating Sema3A expression, inhibiting EndMT markers, reducing atrial fibrosis, and lowering AF vulnerability. This suggests therapeutic potential for naringin in AF treatment.

Low-dose ionizing radiation: Effects on the proliferation and migration of lens epithelial cells via activation of the Wnt/β-catenin pathway

Eye lens opacification (cataract) induced by ionizing radiation is an important concern for radiation protection. Human lens epithelial cells (HLE-B3) were irradiated with γ-rays and radiation effects, including cell proliferation, cell migration, cell cycle distribution, and other changes related to the β-catenin pathway, were determined after 8-72 h and 7 d. In an in vivo model, mice were irradiated; DNA damage (γH2AX foci) in the cell nucleus of the anterior capsule of the lens was detected within 1 h, and radiation effects on the anterior and posterior lens capsules were observed after 3 months. Low-dose ionizing radiation promoted cell proliferation and migration. The expression levels of β-catenin, cyclin D1, and c-Myc were significantly increased in HLE-B3 cells after irradiation and β-catenin was translocated into the cell nucleus (activation of the Wnt/β-catenin pathway). In C57BL/6 J mouse lens, even a very low irradiation dose (0.05 Gy) induced the formation of γH2AX foci, 1 h after irradiation. At 3 months, migratory cells were found in the posterior capsule; expression of β-catenin was increased and it was clustered at the nucleus in the epithelial cells of the lens anterior capsule. The Wnt/β-catenin signaling pathway may an important role in promoting abnormal proliferation and migration of lens epithelial cells after low-dose irradiation.

TFEB-Mediated Lysosomal Restoration Alleviates High Glucose-Induced Cataracts Via Attenuating Oxidative Stress

Purpose

Diabetic cataract (DC) is a visual disorder arising from diabetes mellitus (DM). Autophagy, a prosurvival intracellular process through lysosomal fusion and degradation, has been implicated in multiple diabetic complications. Herein, we performed in vivo and in vitro assays to explore the specific roles of the autophagy-lysosome pathway in DC.

Methods

Streptozotocin-induced DM and incubation in high glucose (HG) led to rat lens opacification. Protein Simple Wes, Western blot, and immunoassay were utilized to investigate autophagic changes in lens epithelial cells (LECs) and lens fiber cells (LFCs). RNA-sequencing (RNA-seq) was performed to explore genetic changes in the lenses of diabetic rats. Moreover, autophagy-lysosomal functions were examined using lysotracker, Western blot, and immunofluorescence analyses in HG-cultured primary rabbit LECs.

Results

First, DM and HG culture led to fibrotic LECs, swelling LFCs, and eventually cataracts. Further analysis showed aberrant autophagic degradation in LECs and LFCs during cataract formation. RNA-seq data revealed that the differentially expressed genes (DEGs) were enriched in the lysosome pathway. In primary LECs, HG treatment resulted in decreased transcription factor EB (TFEB) and cathepsin B (CTSB) activity, and increased lysosomal size and pH values. Moreover, TFEB-mediated dysfunctional lysosomes resulted from excessive oxidative stress in LECs under HG conditions. Furthermore, TFEB activation by curcumin analog C1 alleviated HG-induced cataracts through enhancing lysosome biogenesis and activating protective autophagy, thereby attenuating HG-mediated oxidative damage.

Conclusions

In summary, we first identified that ROS-TFEB-dependent lysosomal dysfunction contributed to autophagy blockage in HG-induced cataracts. Additionally, TFEB-mediated lysosomal restoration might be a promising therapeutic method for preventing and treating DC through mitigating oxidative stress.

Oxidative stress induces inflammation of lens cells and triggers immune surveillance of ocular tissues

Recent reports have challenged the notion that the lens is immune-privileged. However, these studies have not fully identified the molecular mechanism(s) that promote immune surveillance of the lens. Using a mouse model of targeted glutathione (GSH) deficiency in ocular surface tissues, we have investigated the role of oxidative stress in upregulating cytokine expression and promoting immune surveillance of the eye. RNA-sequencing of lenses from postnatal day (P) 1-aged Gclcf/f;Le-CreTg/- (KO) and Gclcf/f;Le-Cre-/- control (CON) mice revealed upregulation of many cytokines (e.g., CCL4, GDF15, CSF1) and immune response genes in the lenses of KO mice. The eyes of KO mice had a greater number of cells in the aqueous and vitreous humors at P1, P20 and P50 than age-matched CON and Gclcw/w;Le-CreTg/- (CRE) mice. Histological analyses revealed the presence of innate immune cells (i.e., macrophages, leukocytes) in ocular structures of the KO mice. At P20, the expression of cytokines and ROS content was higher in the lenses of KO mice than in those from age-matched CRE and CON mice, suggesting that oxidative stress may induce cytokine expression. In vitro administration of the oxidant, hydrogen peroxide, and the depletion of GSH (using buthionine sulfoximine (BSO)) in 21EM15 lens epithelial cells induced cytokine expression, an effect that was prevented by co-treatment of the cells with N-acetyl-l-cysteine (NAC), a antioxidant. The in vivo and ex vivo induction of cytokine expression by oxidative stress was associated with the expression of markers of epithelial-to-mesenchymal transition (EMT), α-SMA, in lens cells. Given that EMT of lens epithelial cells causes posterior capsule opacification (PCO), we propose that oxidative stress induces cytokine expression, EMT and the development of PCO in a positive feedback loop. Collectively these data indicate that oxidative stress induces inflammation of lens cells which promotes immune surveillance of ocular structures.

Recombinant human growth hormone improves the immune status of rats with septic encephalopathy: The role of VEGFR2 in the prevalence of endoplasmic reticulum stress repair module

Septic encephalopathy results from the intense reaction of the immune system to infection. The role of growth hormone (GH) signaling in maintaining brain function is well established; however, the involvement of the vascular endothelial growth factor receptor-2 (VEGFR2) in the potential modulatory effect of GH on septic encephalopathy-associated endoplasmic reticulum stress (ERS) and blood-brain barrier (BBB) permeability is not well-understood. Therefore, after the induction of mid-grade sepsis by cecal ligation/perforation, rats were subcutaneously injected with recombinant human GH (rhGH)/somatropin alone or preceded by the VEGFR2 antagonist WAG-4S for 7 days. rhGH/somatropin reduced bodyweight loss and plasma endotoxin, maintained the hyperthermic state, and improved motor/memory functions. Additionally, rhGH/somatropin increased the junctional E-cadherin and β-catenin pool in the cerebral cortex to enhance the BBB competency, effects that were abolished by VEGFR2 blockade. Also, it activated cortical VEGFR2/mammalian target of the Rapamycin (mTOR) axis to mitigate ERS. The latter was reflected by the deactivation of the inositol-requiring enzyme-1α (IRE1α)/spliced X-box binding protein-1 (XBP1s) trajectory and the reduction in the protein levels of the death markers, C/EBP homologous protein (CHOP)/growth arrest and DNA damage-153 (GADD153), c-jun-N-terminal kinase (JNK), and caspase-3 with the simultaneous augmentation of expression of the unfolded protein response transducer proteinkinaseR-like ERkinase (PERK). Furthermore, rhGH/somatropin suppressed the phosphorylation of eukaryotic initiation factor-2α (eIF2α), upregulated the gene expression of activating transcription factor-4 (ATF4), GADD34, and glucose-regulated protein-78/binding immunoglobulin (GRP78/Bip). Moreover, it increased the glutathione level and reduced lipid peroxidation in the cerebral cortex. The VEGFR2 antagonist reversed the effect of rhGH/somatropin on PERK and IRE1α and boosted the apoptotic markers but neither affected p-eIF2α nor GADD34. Hence, we conclude that VEGFR2 activation by rhGH/somatropin plays a crucial role in assembling the BBB adherens junctions via its antioxidant capacity, ERS relief, and reducing endotoxemia in septic encephalopathy.

Krüppel-like factor 1 (KLF1) promoted the proliferation, migration and invasion of human lens epithelial cells by enhancing the expression of Zinc Finger and BTB Domain Containing 7A (ZBTB7A) and activating Wnt/β-catenin pathway

The epithelial–mesenchymal transition (EMT) of lens epithelial cells enhanced their proliferation and migration and therefore induced the occurrence of posterior capsule opacity (PCO). Some studies revealed that Krüppel-like factor 1 (KLF1) promoted the proliferation and invasion of multiple types of cancer cells. Besides, the expression of KLF1 was elevated in the crystalline lens of cataract patients. However, the effect of KLF1 on the development of PCO remains unclear. In this study, TGF-β2 was used for the stimulation of human lens epithelial cell line to establish EMT (SRA01/04). The KLF1 was overexpressed and knocked down in SRA01/04 cells, the proliferation, migration and invasion of which were detected by clone formation assay, wound healing and transwell assay. In addition, ZBTB7A was overexpressed in KLF1-knocked down SRA01/04 cells, the proliferation and invasion of which were also measured by clone formation assay and transwell assay. KLF1 overexpression promoted the proliferation, migration and invasion of SRA01/04 cells. Moreover, KLF1 also promoted the expression of Vimentin, snail and α-SMA in SRA01/04 cells. KLF1 enhanced the expression of ZBTB7A and β-catenin, resulting in activation of ZBTB7A and Wnt/β-catenin signaling, while overexpression of ZBTB7A abolished the inhibitory effect of knocking down KLF1 on proliferation and invasion of SRA01/04 cells. These results indicated that KLF1 promoted the proliferation, migration and invasion of human lens epithelial cells by activating ZBTB7A and Wnt/β-catenin signaling pathway.

Transforming Growth Factor-β and Oxidative Stress in Cancer: A Crosstalk in Driving Tumor Transformation

Simple Summary

Metabolic changes in tumor microenvironment play a critical role in cancer, related to the accumulated alterations in signaling pathways that control cellular metabolism. Cancer metabolic deregulation is related to specific events such as the control of oxidative stress, and in particular the redox imbalance with aberrant oxidant production and/or a deregulation of the efficacy of the antioxidant systems. In cancer cells, different cytokines are involved in the development and/or progression of cancer; among these cytokines, the transforming growth factor β (TGF-β) is central to tumorigenesis and cancer progression. In tumor cells, it has been demonstrated that there is a close correlation between oxidative stress and TGF-β; this crosstalk strongly contributes to tumorigenesis, both in tumor development and in mediating its invasiveness. This review is addressed to better understanding this crosstalk between TGF-β and oxidative stress in cancer cell metabolism, in an attempt to improve the pharmacological and therapeutic approach against cancer.

Abstract

Cancer metabolism involves different changes at a cellular level, and altered metabolic pathways have been demonstrated to be heavily involved in tumorigenesis and invasiveness. A crucial role for oxidative stress in cancer initiation and progression has been demonstrated; redox imbalance, due to aberrant reactive oxygen species (ROS) production or deregulated efficacy of antioxidant systems (superoxide dismutase, catalase, GSH), contributes to tumor initiation and progression of several types of cancer. ROS may modulate cancer cell metabolism by acting as secondary messengers in the signaling pathways (NF-kB, HIF-1α) involved in cellular proliferation and metastasis. It is known that ROS mediate many of the effects of transforming growth factor β (TGF-β), a key cytokine central in tumorigenesis and cancer progression, which in turn can modulate ROS production and the related antioxidant system activity. Thus, ROS synergize with TGF-β in cancer cell metabolism by increasing the redox imbalance in cancer cells and by inducing the epithelial mesenchymal transition (EMT), a crucial event associated with tumor invasiveness and metastases. Taken as a whole, this review is addressed to better understanding this crosstalk between TGF-β and oxidative stress in cancer cell metabolism, in the attempt to improve the pharmacological and therapeutic approach against cancer.

Kaempferol ameliorates the regulatory effects of PVT1/miR-214 on epithelial-mesenchymal transition through the PAK4/β-catenin axis in SRA01/04 cells

Aim: To investigate whether kaempferol exhibits a protective effect on high glucose-induced epithelial-mesenchymal transition (EMT) by mediating the PVT1/miR-214 and PAK4/β-catenin pathways in SRA01/04 cells. Methods & methods: qRT-PCR and western blot assays were used for gene and protein determination, and migration and invasion assays were conducted. A coimmunoprecipitation assay was used for determining protein interactions. Results: High glucose effectively upregulated PVT1 expression, downregulated miR-214 expression and promoted cell migration and invasion. Kaempferol attenuated high glucose-induced EMT by increasing PVT1 expression and decreasing miR-214 expression. PAK4 was identified as a direct target of miR-214. PAK4 overexpression could rescue the effects of PVT1 deficiency on SRA01/04 cells. Conclusion: Kaempferol ameliorated the regulatory effects of PVT1/miR-214 on high glucose-induced EMT through PAK4/β-catenin in SRA01/04 cells.

MicroRNA-182 promotes epithelial-mesenchymal transition by targeting FOXN3 in gallbladder cancer

Increasing evidence has suggested an association between the expression profiles of microRNAs (miRs) and gallbladder cancer (GBC). Recently, miR-182 has been demonstrated to exert tumor-promoting effects. However, the biological activity and molecular mechanisms of miR-182 in GBC remain unclear. The results of the present study demonstrated that miR-182 expression was significantly upregulated in GBC tissues and cell lines (GBC-SD and SGC-996). In addition, miR-182-knockdown attenuated epithelial-mesenchymal transition (EMT) in GBC cells, as indicated by decreased cell migratory and invasive abilities, decreased vimentin expression, and increased E-cadherin expression. The activities of β-catenin and its downstream factors, Cyclin D1 and c-Myc, were also demonstrated to decrease following miR-182-knockdown. Forkhead box N3 (FOXN3) was identified as the direct target of miR-182. Overexpression of FOXN3 ameliorated EMT and the β-catenin pathway. Taken together, the results of the present study suggested that miR-182 promotes EMT in GBC cells by targeting FOXN3, which suppresses the Wnt/β-catenin pathway.

Hydrogen peroxide-producing NADPH oxidases and the promotion of migratory phenotypes in cancer

The cellular microenvironment plays a critical role in cancer initiation and progression. Exposure to oxidative stress, specifically hydrogen peroxide (H₂O₂), has been linked to aberrant cellular signaling through which the development of cancer may be promoted. Three members of the NADPH oxidase family (NOX4, DUOX1 and DUOX2) explicitly generate this non-radical oxidant in a wide range of tissues, often in support of the inflammatory response. This review summarizes the contributions of each H₂O₂-producing NOX to the invasive behaviors of tumors and/or the epithelial-mesenchymal transition (EMT) in cancer that plays an essential role in metastasis. Tissue localization in tumorigenesis is also highlighted, with patient-derived TCGA microarray data profiled across 31 cancer cohorts to provide a comprehensive guide to the relevance of NOX4/DUOX1/DUOX2 in cancer studies.