Ergolide mediates anti-cancer effects on metastatic uveal melanoma cells and modulates their cellular and extracellular vesicle proteomes

Background

Uveal melanoma is a poor prognosis cancer. Ergolide, a sesquiterpene lactone isolated from Inula Brittanica, exerts anti-cancer properties. The objective of this study was to 1) evaluate whether ergolide reduced metastatic uveal melanoma (MUM) cell survival/viability in vitro and in vivo; and 2) to understand the molecular mechanism of ergolide action.

Methods

Ergolide bioactivity was screened via long-term proliferation assay in UM/MUM cells and in zebrafish MUM xenograft models. Mass spectrometry profiled proteins modulated by ergolide within whole cell or extracellular vesicle (EVs) lysates of the OMM2.5 MUM cell line. Protein expression was analyzed by immunoblots and correlation analyses to UM patient survival used The Cancer Genome Atlas (TCGA) data.

Results

Ergolide treatment resulted in significant, dose-dependent reductions (48.5 to 99.9%; p<0.0001) in OMM2.5 cell survival in vitro and of normalized primary zebrafish xenograft fluorescence (56%; p<0.0001) in vivo, compared to vehicle controls. Proteome-profiling of ergolide-treated OMM2.5 cells, identified 5023 proteins, with 52 and 55 proteins significantly altered at 4 and 24 hours, respectively ( p<0.05; fold-change >1.2). Immunoblotting of heme oxygenase 1 (HMOX1) and growth/differentiation factor 15 (GDF15) corroborated the proteomic data. Additional proteomics of EVs isolated from OMM2.5 cells treated with ergolide, detected 2931 proteins. There was a large overlap with EV proteins annotated within the Vesiclepedia compendium. Within the differentially expressed proteins, the proteasomal pathway was primarily altered. Interestingly, BRCA2 and CDKN1A Interacting Protein (BCCIP) and Chitinase Domain Containing 1 (CHID1), were the only proteins significantly differentially expressed by ergolide in both the OMM2.5 cellular and EV isolates and they displayed inverse differential expression in the cells versus the EVs.

Conclusions

Ergolide is a novel, promising anti-proliferative agent for UM/MUM. Proteomic profiling of OMM2.5 cellular/EV lysates identified candidate pathways elucidating the action of ergolide and putative biomarkers of UM, that require further examination.

Evaluation of the Therapeutic Potential of Histone Deacetylase 6 Inhibitors for Primary and Metastatic Uveal Melanoma

Patients diagnosed with metastatic uveal melanoma (MUM) have a poor survival prognosis. Unfortunately for this rare disease, there is no known cure and suitable therapeutic options are limited. HDAC6 inhibitors (HDAC6i) are currently in clinical trials for other cancers and show potential beneficial effects against tumor cell survival in vitro and in vivo. In MUM cells, HDAC6i show an anti-proliferative effect in vitro and in preclinical xenograft models. The use of HDAC6 inhibitors as a treatment option for MUM should be explored further. Therefore, this review discusses (1) what is known about HDAC6i in MUM and (2) whether HDAC6 inhibitors offer a potential therapeutic option for MUM.

Harnessing the Role of HDAC6 in Idiopathic Pulmonary Fibrosis: Design, Synthesis, Structural Analysis, and Biological Evaluation of Potent Inhibitors

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease characterized by a progressive-fibrosing phenotype. IPF has been associated with aberrant HDAC activities confirmed by our immunohistochemistry studies on HDAC6 overexpression in IPF lung tissues. We herein developed a series of novel hHDAC6 inhibitors, having low inhibitory potency over hHDAC1 and hHDAC8, as potential pharmacological tools for IPF treatment. Their inhibitory potency was combined with low in vitro and in vivo toxicity. Structural analysis of 6h and structure-activity relationship studies contributed to the optimization of the binding mode of the new molecules. The best-performing analogues were tested for their efficacy in inhibiting fibrotic sphere formation and cell viability, proving their capability in reverting the IPF phenotype. The efficacy of analogue 6h was also determined in a validated human lung model of TGF-β1-dependent fibrogenesis. The results highlighted in this manuscript may pave the way for the identification of first-in-class molecules for the treatment of IPF.

Selective Histone Deacetylase 6 Inhibitors Restore Cone Photoreceptor Vision or Outer Segment Morphology in Zebrafish and Mouse Models of Retinal Blindness

Blindness arising from retinal or macular degeneration results in significant social, health and economic burden. While approved treatments exist for neovascular (‘wet’) age-related macular degeneration, new therapeutic targets/interventions are needed for the more prevalent atrophic (‘dry’) form of age-related macular degeneration. Similarly, in inherited retinal diseases, most patients have no access to an effective treatment. Although macular and retinal degenerations are genetically and clinically distinct, common pathological hallmarks can include photoreceptor degeneration, retinal pigment epithelium atrophy, oxidative stress, hypoxia and defective autophagy. Here, we evaluated the potential of selective histone deacetylase 6 inhibitors to preserve retinal morphology or restore vision in zebrafish atp6v0e1^–/– and mouse rd10 models. Histone deacetylase 6 inhibitor, tubastatin A-treated atp6v0e1^–/– zebrafish show marked improvement in photoreceptor outer segment area (44.7%, p = 0.027) and significant improvement in vision (8-fold, p ≤ 0.0001). Tubastatin A-treated rd10/rd10 retinal explants show a significantly (p = 0.016) increased number of outer-segment labeled cone photoreceptors. In vitro, ATP6V0E1 regulated HIF-1α activity, but significant regulation of HIF-1α by histone deacetylase 6 inhibition in the retina was not detected. Proteomic profiling identified ubiquitin-proteasome, phototransduction, metabolism and phagosome as pathways, whose altered expression correlated with histone deacetylase 6 inhibitor mediated restoration of vision.

Emerging Drug Therapies for Inherited Retinal Dystrophies

Worldwide, 1 in 2000 people suffer from inherited retinal dystrophies (IRD). Individuals with IRD typically present with progressive vision loss that ultimately results in blindness. Unfortunately, effective treatment options are not widely available due to the genetic and clinical heterogeneity of these diseases. There are multiple gene, cell, and drug-based therapies in various phases of clinical trials for IRD. This mini-review documents current progress made in drug-based clinical trials for treating IRD.

Enhancing Understanding of the Visual Cycle by Applying CRISPR/Cas9 Gene Editing in Zebrafish

During the vertebrate visual cycle, all-trans-retinal is exported from photoreceptors to the adjacent RPE or Müller glia wherein 11-cis-retinal is regenerated. The 11-cis chromophore is returned to photoreceptors, forming light-sensitive visual pigments with opsin GPCRs. Dysfunction of this process perturbs phototransduction because functional visual pigment cannot be generated. Mutations in visual cycle genes can result in monogenic inherited forms of blindness. Though key enzymatic processes are well characterized, questions remain as to the physiological role of visual cycle proteins in different retinal cell types, functional domains of these proteins in retinoid biochemistry and in vivo pathogenesis of disease mutations. Significant progress is needed to develop effective and accessible treatments for inherited blindness arising from mutations in visual cycle genes. Here, we review opportunities to apply gene editing technology to two crucial visual cycle components, RPE65 and CRALBP. Expressed exclusively in the human RPE, RPE65 enzymatically converts retinyl esters into 11-cis retinal. CRALBP is an 11-cis-retinal binding protein expressed in human RPE and Muller glia. Loss-of-function mutations in either protein results in autosomal recessive forms of blindness. Modeling these human conditions using RPE65 or CRALBP murine knockout models have enhanced our understanding of their biochemical function, associated disease pathogenesis and development of therapeutics. However, rod-dominated murine retinae provide a challenge to assess cone function. The cone-rich zebrafish model is amenable to cost-effective maintenance of a variety of strains. Interestingly, gene duplication in zebrafish resulted in three Rpe65 and two Cralbp isoforms with differential temporal and spatial expression patterns. Functional investigations of zebrafish Rpe65 and Cralbp were restricted to gene knockdown with morpholino oligonucleotides. However, transient silencing, off-target effects and discrepancies between knockdown and knockout models, highlight a need for more comprehensive alternatives for functional genomics. CRISPR/Cas9 in zebrafish has emerged as a formidable technology enabling targeted gene knockout, knock-in, activation, or silencing to single base-pair resolution. Effective, targeted gene editing by CRISPR/Cas9 in zebrafish enables unprecedented opportunities to create genetic research models. This review will discuss existing knowledge gaps regarding RPE65 and CRALBP. We explore the benefits of CRISPR/Cas9 to establish innovative zebrafish models to enhance knowledge of the visual cycle.

Gastrodia elata Blume (tianma) mobilizes neuro-protective capacities

Tianma (Gastrodia elata Blume) is a traditional Chinese medicine (TCM) often used for the treatment of headache, convulsions, hypertension and neurodegenerative diseases. Tianma also modulates the cleavage of the amyloid precursor protein App and cognitive functions in mice. The neuronal actions of tianma thus led us to investigate its specific effects on neuronal signalling. Accordingly, this pilot study was designed to examine the effects of tianma on the proteome metabolism in differentiated mouse neuronal N2a cells using an iTRAQ (isobaric tags for relative and absolute quantitation)-based proteomics research approach. We identified 2178 proteins, out of which 74 were found to be altered upon tianma treatment in differentiated mouse neuronal N2a cells. Based on the observed data obtained, we hypothesize that tianma could promote neuro-regenerative processes by inhibiting stress-related proteins and mobilizing neuroprotective genes such as Nxn, Dbnl, Mobkl3, Clic4, Mki67 and Bax with various regenerative modalities and capacities related to neuro-synaptic plasticity.

Tianma modulates proteins with various neuro-regenerative modalities in differentiated human neuronal SH-SY5Y cells

Tianma (Rhizoma gastrodiae) is the dried rhizome of the plant Gastrodia elata Blume (Orchidaceae family). As a medicinal herb in traditional Chinese medicine (TCM) its functions are to control convulsions, pain, headache, dizziness, vertigo, seizure, epilepsy and others. In addition, tianma is frequently used for the treatment of neurodegenerative disorders though the mechanism of action is widely unknown. Accordingly, this study was designed to examine the effects of tianma on the proteome metabolism in differentiated human neuronal SH-SY5Y cells to explore its specific effects on neuronal signaling pathways. Using an iTRAQ (isobaric tags for relative and absolute quantitation)-based proteomics research approach, we identified 2390 modulated proteins, out of which 406 were found to be altered by tianma in differentiated human neuronal SH-SY5Y cells. Based on the observed data, we hypothesize that tianma promotes neuro-regenerative signaling cascades by controlling chaperone/proteasomal degradation pathways (e.g. CALR, FKBP3/4, HSP70/90) and mobilizing neuro-protective genes (such as AIP5) as well as modulating other proteins (RTN1/4, NCAM, PACSIN2, and PDLIM1/5) with various regenerative modalities and capacities related to neuro-synaptic plasticity.