Regulated differentiation of WERI-Rb-1 cells into retinal neuron-like cells

Glyburide confers neuroprotection against age-related macular degeneration (AMD)

Glyburide, a sulfonylurea drug used to treat type 2 diabetes, boasts neuroprotective effects by targeting the sulfonylurea receptor 1 (SUR1) and associated ion channels in various cell types, including those in the central nervous system and the retina. Previously, we demonstrated that glyburide therapy improved retinal function and structure in a rat model of diabetic retinopathy. In the present study, we explore the application of glyburide in non-neovascular ("dry") age-related macular degeneration (AMD), another progressive disease characterized by oxidative stress-induced damage and neuroinflammation that trigger cell death in the retina. We show that glyburide administration to a human cone cell line confers protection against oxidative stress, inflammasome activation, and apoptosis. To corroborate our in vitro results, we also conducted a case-control study, controlling for AMD risk factors and other diabetes medications. It showed that glyburide use in patients reduces the odds of new-onset dry AMD. A positive dose-response relationship is observed from this analysis, in which higher cumulative doses of glyburide further reduce the odds of new-onset dry AMD. In the quest for novel therapies for AMD, glyburide emerges as a promising repurposable drug given its known safety profile. The results from this study provide insights into the multifaceted actions of glyburide and its potential as a neuroprotective agent for retinal diseases; however, further preclinical and clinical studies are needed to validate its therapeutic potential in the context of degenerative retinal disorders such as AMD.

Protein expression of nucleolar protein 12 in the retina and its implication in protection of retina from UV irradiation damage

Nucleolar protein 12 (NOL12), one of the nucleolar proteins which are primarily expressed in the nucleolus and play key roles in RNA metabolism, cell proliferation, cell cycle, and cell survival, is widely expressed in various species and multiple organs. Although it has been reported that the mRNA of Drosophila NOL12 homolog viriato is expressed in the eyes of Drosophila, the protein expression of NOL12 in mammalian eyes remains to be elucidated. In this study, we showed through immunohistochemistry that NOL12 was present in the rat retina, with predominant distribution in the cytoplasm of the retinal neuronal cells. In the human retinoblastoma cell line WERI-Rb1, we found that altering NOL12 expression led to a change in WERI-Rb1 cell viability. Knocking down NOL12 expression decreased cell viability. In contrast, overexpressing NOL12 increased cell viability. Furthermore, increasing NOL12 expression inhibited ultraviolet (UV)-induced apoptosis. These findings demonstrated that NOL12 may play an important protective role in retinal cells. In the WERI-Rb1 cells exposed to UV irradiation, we detected that NOL12 was degraded, but this degradation could be attenuated by a pan-Caspase inhibitor. Notably, the inhibitory effect of NOL12 against UV-induced apoptosis could be restrained by increasing the expression of ATR serine/threonine kinase (ATR), a kinase that, when activated by severe DNA damage, can result in apoptosis. We also found that upregulating NOL12 inhibited the activation of ATR caused by UV irradiation. Additionally, inhibiting ATR activity reduced apoptosis resulting from both silencing NOL12 expression and UV exposure. Thus, NOL12 may protect against UV irradiation-induced retinal damage by inhibiting ATR activity.

Ciliary Neurotrophic Factor Derived From Astrocytes Protects Retinal Ganglion Cells Through PI3K/AKT, JAK/STAT, and MAPK/ERK Pathways

Purpose

The purpose of this study was to investigate the roles of ciliary neurotrophic factor (CNTF) on the protective effects of astrocytes on retinal ganglion cells (RGCs).

Methods

Primary RGCs were isolated from neonatal rats. Oxidative stress was induced, and the effects of co-culture with astrocytes and CNTF treatment on RGCs were evaluated. The pathways commonly altered by astrocytes and CNTF were investigated. Effects of each pathway were investigated using pathway inhibitors against PI3K/AKT, JAK/STAT, and MAPK/ERK. RNA sequencing was performed to identify the genes upregulated and downregulated by CNTF treatment.

Results

Astrocytes improved the viability and increased β3-tubulin expression in RGCs. The concentration of CNTF increased in the RGC-astrocyte co-culture medium. The protective effects of astrocytes were abolished by neutralization with the anti-CNTF antibody; thus, CNTF may play an important role in the effects mediated by astrocytes. Furthermore, CNTF treatment alone enhanced the viability and β3-tubulin expression of RGCs and increased the population of viable RGCs under oxidative stress. The PI3K/AKT pathway was associated with both RGC viability and β3-tubulin expression. However, the JAK/STAT pathway increased the viability of RGCs, whereas the MAPK/ERK pathway was associated with β3-tubulin expression. RNA sequencing revealed the CNTF-upregulated genes associated with response to DNA damage and downregulated genes associated with photoreceptor cell differentiation.

Conclusions

Our data revealed protective effects of astrocyte-derived CNTF on RGCs. In addition, we showed that multiple pathways exert these protective effects and identified the novel genes involved. These results may be helpful in developing treatments for RGC injury.

mTOR inhibition by TAK-228 is effective against growth, survival and angiogenesis in preclinical retinoblastoma models

We and others have shown that aberrant activation of the mammalian target of rapamycin (mTOR) signalling is essential for retinoblastoma progression and has potential therapeutic value. TAK‐228 is a potent inhibitor of mTOR1 and 2 with preclinical activity in a variety of cancers. In this study, we report that TAK‐228 is a dual inhibitor of retinoblastoma and angiogenesis. TAK‐228 inhibits growth and induces apoptosis in a panel of retinoblastoma cell lines, with IC50 at ~0.2 μM. Under the same experimental conditions, TAK‐228 was less effective in inhibiting growth and survival in normal retinal and fibroblast cells than retinoblastoma cells. In addition, TAK‐228 inhibited retinal endothelial cell capillary network formation, migration, growth and survival. We further demonstrate that TAK‐228 inhibits retinoblastoma and retinal angiogenesis through inhibiting mTOR signalling. Rescue studies confirm that mTOR is the target of TAK‐228 in both retinoblastoma and retinal endothelial cells. Finally, we confirm the inhibitory effects of TAK‐228 on tumor and angiogenesis in retinoblastoma xenograft mouse model. Our findings provide a preclinical rationale to explore TAK‐228 as a strategy to treat retinoblastoma and highlight the therapeutic value of targeting mTOR in retinoblastoma.

Carbon Nanotube Polymer Scaffolds as a Conductive Alternative for the Construction of Retinal Sheet Tissue

With the great success of graphene in the biomedical field, carbon nanotubes have attracted increasing attention for different applications in ophthalmology. Here, we report a novel retinal sheet composed of carbon nanotubes (CNTs) and poly(lactic-co-glycolic acid) (PLGA) that can enhance retinal cell therapy. By tuning our CNTs to regulate the mechanical characteristics of retina sheets, we were able to improve the in vitro viability of retinal ganglion cells derived from human-induced pluripotent stem cells incorporated into CNTs. Engrafted retinal ganglion cells displayed signs of regenerating processes along the optic nerve. Compared with PLGA scaffolds, CNT-PLGA retinal sheet tissue has excellent electrical conductivity, biocompatibility, and biodegradation. This new biomaterial offers new insight into retinal injury, repair, and regeneration.

LncRNA MBLN1-AS1 inhibits the progression of retinoblastoma through targeting miR-338-5p-Wnt/β-catenin signaling pathway

OBJECTIVE AND DESIGN

Retinoblastoma is the most common primary intraocular malignancy of childhood, which brings a heavy burden to the countries across the world, especially the developing countries. It has been shown that lncRNA muscleblind-like 1 antisense RNA 1 (MBNL1-AS1) exerts anti-tumor effects in various cancers, including bladder cancer, papillary thyroid cancer, and retinoblastoma. In the present study, we hypothesized that MBNL1-AS1 might play a protective role against retinoblastoma.

METHODS

The expression of MBNL1-AS1 and its potential target miR-338-5p were evaluated in retinoblastoma cell line by real-time quantitative PCR and western blot. The involvement of MBNL1-AS1-miR-338-5p in the cell proliferation was evaluated by cell counting kit-8 (CCK8), and colony formation assay. The cell migration was evaluated by Transwell assay in Y79 cells, a retinoblastoma cell line. The involvement of MBNL1-AS1-miR-338-5p in tumor formation was also evaluated in mice.

RESULTS

It was found that MBNL1-AS1 overexpression inhibited proliferation and migration in Y79 cells. In addition, the inhibitory effects of MBNL1-AS1 on Y79 cells were significantly reversed in the presence of miR-338-5p mimics, and MBNL1-AS1 overexpression significantly decreased miR-338-5p level in Y79 cells. Furthermore, MBNL1-AS1 overexpression significantly inhibited Wnt/β-catenin signaling pathway, and this inhibitory effect was almost lost in the presence of miR-338-5p mimics. Finally, our in vivo study showed that MBNL1-AS1 overexpression significantly inhibited Y79-induced retinoblastoma in mice, and this inhibitory effect was lost in the presence of miR-338-5p mimics.

CONCLUSION

Our study shows that MBNL1-AS1 exerts its anti-tumor effect by targeting miR-338-5p, thereby inactivating wnt/β-catenin signaling pathway in retinoblastoma.

Ascorbate-induced oxidative stress mediates TRP channel activation and cytotoxicity in human etoposide-sensitive and -resistant retinoblastoma cells

There are indications that pharmacological doses of ascorbate (Asc) used as an adjuvant improve the chemotherapeutic management of cancer. This favorable outcome stems from its cytotoxic effects due to prooxidative mechanisms. Since regulation of intracellular Ca2+ levels contributes to the maintenance of cell viability, we hypothesized that one of the effects of Asc includes disrupting regulation of intracellular Ca2+ homeostasis. Accordingly, we determined if Asc induced intracellular Ca2+ influx through activation of pertussis sensitive Gi/o-coupled GPCR which in turn activated transient receptor potential (TRP) channels in both etoposide-resistant and -sensitive retinoblastoma (WERI-Rb1) tumor cells. Ca2+ imaging, whole-cell patch-clamping, and quantitative real-time PCR (qRT-PCR) were performed in parallel with measurements of RB cell survival using Trypan Blue cell dye exclusion. TRPM7 gene expression levels were similar in both cell lines whereas TRPV1, TRPM2, TRPA1, TRPC5, TRPV4, and TRPM8 gene expression levels were downregulated in the etoposide-resistant WERI-Rb1 cells. In the presence of extracellular Ca2+, 1 mM Asc induced larger intracellular Ca2+ transients in the etoposide-resistant WERI-Rb1 than in their etoposide-sensitive counterpart. With either 100 µM CPZ, 500 µM La3+, 10 mM NAC, or 100 µM 2-APB, these Ca2+ transients were markedly diminished. These inhibitors also had corresponding inhibitory effects on Asc-induced rises in whole-cell currents. Pertussis toxin (PTX) preincubation blocked rises in Ca2+ influx. Microscopic analyses showed that after 4 days of exposure to 1 mM Asc cell viability fell by nearly 100% in both RB cell lines. Taken together, one of the effects underlying oxidative mediated Asc-induced WERI-Rb1 cytotoxicity stems from its promotion of Gi/o coupled GPCR mediated increases in intracellular Ca2+ influx through TRP channels. Therefore, designing drugs targeting TRP channel modulation may be a viable approach to increase the efficacy of chemotherapeutic treatment of RB. Furthermore, Asc may be indicated as a possible supportive agent in anti-cancer therapies.

Quantifiable In Vivo Imaging Biomarkers of Retinal Regeneration by Photoreceptor Cell Transplantation

Purpose

Short-term improvements in retinal anatomy are known to occur in preclinical models of photoreceptor transplantation. However, correlative changes over the long term are poorly understood. We aimed to develop a quantifiable imaging biomarker grading scheme, using noninvasive multimodal confocal scanning laser ophthalmoscopy (cSLO) imaging, to enable serial evaluation of photoreceptor transplantation over the long term.

Methods

Photoreceptor cell suspensions or sheets from rhodopsin-green fluorescent protein mice were transplanted subretinally, into either NOD.CB17-Prkdc^scid/J or C3H/HeJ-Pde6b^rd1 mice. Multimodal cSLO imaging was performed serially for up to three months after transplantation. Imaging biomarkers were scored, and a grade was defined for each eye by integrating the scores. Image grades were correlated with immunohistochemistry (IHC) data.

Results

Multimodal imaging enabled the extraction of quantitative imaging biomarkers including graft size, GFP intensity, graft length, on-target graft placement, intra-graft lamination, hemorrhage, retinal atrophy, and periretinal proliferation. Migration of transplanted material was observed. Changes in biomarker scores and grades were detected in 14/16 and 7/16 eyes, respectively. A high correlation was found between image grades and IHC parameters.

Conclusions

Serial evaluation of multiple imaging biomarkers, when integrated into a per-eye grading scheme, enabled comprehensive tracking of longitudinal changes in photoreceptor cell grafts over time. The application of systematic multimodal in vivo imaging could be useful in increasing the efficiency of preclinical retinal cell transplantation studies in rodents and other animal models.

Translational Relevance

By allowing longitudinal evaluation of the same animal over time, and providing quantifiable biomarkers, non-invasive multimodal imaging improves the efficiency of retinal transplantation studies in animal models. Such assays will facilitate the development of cell therapy for retinal diseases.

Single-cell RNA sequencing study of retinal immune regulators identified CD47 and CD59a expression in photoreceptors-Implications in subretinal immune regulation

The neuroretina is protected by its own defense system, that is microglia and the complement system. Under normal physiological conditions, microglial activation is tightly regulated by the neurons although the underlying mechanism remains elusive. Using published single-cell RNA sequencing data sets, we found that immune regulatory molecules including CD200, CD47, CX3CL1, TGFβ, and complement inhibitor CD59a are expressed by various retinal neurons. Importantly, we found that photoreceptors express higher levels of CD47 and CD59a, which was further confirmed in cultured 661W cells, WERI-Rb1 cells, and microdissected photoreceptors from human eyes. The expression of CD59a mRNA in 661W cells was upregulated by TNFα and hypoxia, whereas LPS, hypoxia, and IL-4 upregulated CD47 mRNA expression in 661W cells. Immunofluorescence staining detected strong CD59a immunoreactivity in the outer nuclear layer, inner/outer segments, and discrete staining in ganglion cell layer (GCL), inner plexiform layer (IPL), and outer plexiform layer. The expression of CD59a in photoreceptors was increased in the detached retina, but decreased in retinas from experimental autoimmune uveoretinitis (EAU) mice. In EAU retina, CD59a was highly expressed by active immune cells. CD47 was detected in GCL, IPL, and inner nuclear layer and some photoreceptors. The expression of CD47 in photoreceptors was also increased in the detached retina but decreased in EAU retina. In a coculture system, 661W enhanced arginase-1 and reduced IL-6 mRNA expression in BV2 microglial cells. Our results suggest that photoreceptors express immune regulatory molecules and may have the potential to regulate immune activation in the outer retina/subretinal space under pathophysiological conditions.

Downregulation of Nodal inhibits metastatic progression in retinoblastoma

Retinoblastoma is the most common intraocular malignancy in children. We previously found that the ACVR1C/SMAD2 pathway is significantly upregulated in invasive retinoblastoma samples from patients. Here we studied the role of an ACVR1C ligand, Nodal, in regulating growth and metastatic dissemination in retinoblastoma. Inhibition of Nodal using multiple short hairpin (shRNAs) in WERI Rb1 and Y79 retinoblastoma cell cultures reduced growth by more than 90%, as determined by CCK-8 growth assay. Proliferation was also significantly inhibited, as found by Ki67 assay. These effects were paralleled by inhibition in the phosphorylation of the downstream effector SMAD2, as well as induction of apoptosis, as we observed more than three-fold increase in the percentage of cells positive for cleaved-caspase-3 or expressing cleaved-PARP1. Importantly, we found that downregulation of Nodal potently suppressed invasion in vitro, by 50 to 80%, as determined by transwell invasion assay (p = 0.02). Using an orthotopic model of retinoblastoma in zebrafish, we found 34% reduction in the ability of the cells to disseminate outside the eye, when Nodal was knocked down by shRNA (p = 0.0003). These data suggest that Nodal plays an important role in promoting growth, proliferation and invasion in retinoblastoma, and can be considered a new therapeutic target for both primary tumor growth and metastatic progression.

ACVR1C/SMAD2 signaling promotes invasion and growth in retinoblastoma

Retinoblastoma is the most common intraocular cancer in children. While the primary tumor can often be treated by local or systemic chemotherapy, metastatic dissemination is generally resistant to therapy and remains a leading cause of pediatric cancer death in much of the world. In order to identify new therapeutic targets in aggressive tumors, we sequenced RNA transcripts in five snap frozen retinoblastomas which invaded the optic nerve and five which did not. A three-fold increase was noted in mRNA levels of ACVR1C/ALK7, a type I receptor of the TGF-β family, in invasive retinoblastomas, while downregulation of DACT2 and LEFTY2, negative modulators of the ACVR1C signaling, was observed in most invasive tumors. A two- to three-fold increase in ACVR1C mRNA was also found in invasive WERI Rb1 and Y79 cells as compared to non-invasive cells in vitro. Transcripts of ACVR1C receptor and its ligands (Nodal, Activin A/B, and GDF3) were expressed in six retinoblastoma lines, and evidence of downstream SMAD2 signaling was present in all these lines. Pharmacological inhibition of ACVR1C signaling using SB505124, or genetic downregulation of the receptor using shRNA potently suppressed invasion, growth, survival, and reduced the protein levels of the mesenchymal markers ZEB1 and Snail. The inhibitory effects on invasion, growth, and proliferation were recapitulated by knocking down SMAD2, but not SMAD3. Finally, in an orthotopic zebrafish model of retinoblastoma, a 55% decrease in tumor spread was noted (p=0.0026) when larvae were treated with 3 μM of SB505124, as compared to DMSO. Similarly, knockdown of ACVR1C in injected tumor cells using shRNA also resulted in a 54% reduction in tumor dissemination in the zebrafish eye as compared to scrambled shRNA control (p=0.0005). Our data support a role for the ACVR1C/SMAD2 pathway in promoting invasion and growth of retinoblastoma.