Long Non-Coding RNA GAS5 Targeting microRNA-21 to Suppress the Invasion and Epithelial-Mesenchymal Transition of Uveal Melanoma

From diagnosis to therapy: The transformative role of lncRNAs in eye cancer management

The genomic era has brought about a transformative shift in our comprehension of cancer, unveiling the intricate molecular landscape underlying disease development. Eye cancers (ECs), encompassing diverse malignancies affecting ocular tissues, pose distinctive challenges in diagnosis and management. Long non-coding RNAs (lncRNAs), an emerging category of non-coding RNAs, are pivotal actors in the genomic intricacies of eye cancers. LncRNAs have garnered recognition for their multifaceted roles in gene expression regulation and influence on many cellular processes. Many studies support that the lncRNAs have a role in developing various cancers. Recent investigations have pinpointed specific lncRNAs associated with ECs, including retinoblastoma and uveal melanoma. These lncRNAs exert control over critical pathways governing tumor initiation, progression, and metastasis, endowing them with the ability to function as evaluation, predictive, and therapeutic indicators. The article aims to synthesize the existing information concerning the functions of lncRNAs in ECs, elucidating their regulatory mechanisms and clinical significance. By delving into the lncRNAs' expanding relevance in the modulation of oncogenic and tumor-suppressive networks, we gain a deeper understanding of the molecular complexities intrinsic to these diseases. In our exploration of the genomic intricacies of ECs, lncRNAs introduce a fresh perspective, providing an opportunity to function as clinical and therapeutic indicators, and they also have therapeutic benefits that show promise for advancing the treatment of ECs. This comprehensive review bridges the intricate relationship between lncRNAs and ECs within the context of the genomic era.

Mechanisms of human umbilical cord mesenchymal stem cells-derived exosomal lncRNA GAS5 in alleviating EMT of HPMCs via Wnt/β-catenin signaling pathway

BACKGROUND

Prolonged peritoneal dialysis (PD) can result in epithelial-to-mesenchymal transition (EMT) and peritoneal fibrosis (PF), which can cause patients to discontinue PD. It is imperative to urgently investigate effective measures to mitigate PF. This study aims to reveal mechanisms of exosomal lncRNA GAS5 derived from human umbilical cord mesenchymal stem cells (hUC-MSCs) on EMT of human peritoneal mesothelial cells (HPMCs) under high glucose (HG) conditions.

METHODS

HPMCs were stimulated with 2.5% glucose. The effects on EMT of HPMCs were observed by using an hUC-MSC conditioned medium (hUC-MSC-CM) and extracted exosomes. After hUC-MSCs were transfected with GAS5 siRNA, exosomes were extracted to act on HPMCs for detecting EMT markers, PTEN, and Wnt/β-catenin pathway, lncRNA GAS5 and miR-21 expressions in HPMCs.

RESULTS

We found that HG could induce the EMT of HPMCs. Compared with the HG group, the hUC-MSC-CM could alleviate the EMT of HPMCs induced by HG through exosomes. Exosomes in the hUC-MSC-CM entered HPMCs, by transferring lncRNA GAS5 to HPMCs, which down-regulates miR-21 and up-regulates PTEN, thus finally alleviating EMT of HPMCs. The Wnt/β-catenin pathway plays an essential role in alleviating EMT of HPMCs by exosomes in the hUC-MSC-CM. By transferring lncRNA GAS5 to HPMCs, exosomes derived from hUC-MSCs may competitively bind to miR-21 to regulate suppression on target PTEN genes and alleviate EMT of HPMCs through the Wnt/β-catenin pathway.

CONCLUSIONS

Exosomes from the hUC-MSCs-CM could alleviate the EMT of HPMCs induced by HG via regulating lncRNA GAS5/miR-21/PTEN through the Wnt/β-catenin signaling pathway.

Genetics and RNA Regulation of Uveal Melanoma

Uveal melanoma (UM) is the most common intraocular malignant tumor and the most frequent melanoma not affecting the skin. While the rate of UM occurrence is relatively low, about 50% of patients develop metastasis, primarily to the liver, with lethal outcome despite medical treatment. Notwithstanding that UM etiopathogenesis is still under investigation, a set of known mutations and chromosomal aberrations are associated with its pathogenesis and have a relevant prognostic value. The most frequently mutated genes are BAP1, EIF1AX, GNA11, GNAQ, and SF3B1, with mutually exclusive mutations occurring in GNAQ and GNA11, and almost mutually exclusive ones in BAP1 and SF3B1, and BAP1 and EIF1AX. Among chromosomal aberrations, monosomy of chromosome 3 is the most frequent, followed by gain of chromosome 8q, and full or partial loss of chromosomes 1 and 6. In addition, epigenetic mechanisms regulated by non-coding RNAs (ncRNA), namely microRNAs and long non-coding RNAs, have also been investigated. Several papers investigating the role of ncRNAs in UM have reported that their dysregulated expression affects cancer-related processes in both in vitro and in vivo models. This review will summarize current findings about genetic mutations, chromosomal aberrations, and ncRNA dysregulation establishing UM biology.

5‑Aza‑dC suppresses melanoma progression by inhibiting GAS5 hypermethylation

The in‑depth study of melanoma pathogenesis has revealed that epigenetic modifications, particularly DNA methylation, is a universal inherent feature of the development and progression of melanoma. In the present study, the analysis of the tumor suppressor gene growth arrest‑specific transcript 5 (GAS5) demonstrated that its expression was downregulated in melanoma, and its expression level had a certain negative association with its methylation modification level. The promoter of GAS5 presented with detectable CpG islands, and methylation‑specific polymerase chain reaction analysis demonstrated that GAS5 was actually modified by methylation in melanoma tissues and cells; however, no methylation modification of GAS5 was detected in normal tissues. Following the treatment of melanoma cells with 5‑Aza‑2'‑deoxycytidine (5‑Aza‑dC), GAS5 methylation was significantly reversed. The analysis of melanoma cell proliferation revealed that 5‑Aza‑dC inhibited A375 and SK‑MEL‑110 cell proliferation in a time‑dependent manner. Further analysis of apoptosis demonstrated that 5‑Aza‑dC significantly increased the apoptosis level of the two cell lines. Moreover, migration analysis of melanoma cells revealed that 5‑Aza‑dC significantly reduced cell migration. Furthermore, 5‑Aza‑dC significantly decreased the invasive ability of the two cell lines. However, when the expression of GAS5 was silenced, the effects of 5‑Aza‑dC on cell proliferation, apoptosis, invasion and migration were not significant. Furthermore, the subcutaneous injection of A375 cells in nude mice successfully resulted in xenograft tumor formation. However, following an intraperitoneal injection of 5‑Aza‑dC, the volume and weight of xenograft tumors and Ki‑67 expression were significantly reduced, and caspase‑3 activity and GAS5 expression were enhanced; following the silencing of GAS5, the antitumor effect of 5‑Aza‑dC was significantly blocked. On the whole, the present study demonstrates that 5‑Aza‑dC inhibits the growth of melanoma, and its function may be related to the methylation modification of GAS5.

Regulation of epigenetic homeostasis in uveal melanoma and retinoblastoma

Uveal melanoma (UM) and retinoblastoma (RB), which cause blindness and even death, are the most frequently observed primary intraocular malignancies in adults and children, respectively. Epigenetic studies have shown that changes in the epigenome contribute to the rapid progression of both UM and RB following classic genetic changes. The loss of epigenetic homeostasis plays an important role in oncogenesis by disrupting the normal patterns of gene expression. The targetable nature of epigenetic modifications provides a unique opportunity to optimize treatment paradigms and establish new therapeutic options for both UM and RB with these aberrant epigenetic modifications. We aimed to review the research findings regarding relevant epigenetic changes in UM and RB. Herein, we 1) summarize the literature, with an emphasis on epigenetic alterations, including DNA methylation, histone modifications, RNA modifications, noncoding RNAs and an abnormal chromosomal architecture; 2) elaborate on the regulatory role of epigenetic modifications in biological processes during tumorigenesis; and 3) propose promising therapeutic candidates for epigenetic targets and update the list of epigenetic drugs for the treatment of UM and RB. In summary, we endeavour to depict the epigenetic landscape of primary intraocular malignancy tumorigenesis and provide potential epigenetic targets in the treatment of these tumours.

Do Extracellular RNAs Provide Insight into Uveal Melanoma Biology?

Simple Summary

The study of RNAs in the extracellular environment in physiological and pathological conditions has become a growing field of research with intriguing applications in diagnostics and prognostics. Such extracellular RNAs are passively or actively released by all cells into biological fluids to spread biological signals to other cells. The perturbation of such RNA-based cell-to-cell communications in cancer can be easily identified by molecular analysis of liquid biopsies, even if source cells secreting RNAs are often elusive. In uveal melanoma (UM), extracellular RNAs can be assayed in serum, plasma, and vitreous and aqueous humor. In this review, we explore the possibility that extracellular RNA alterations in UM could partially match with RNA dysregulations observed in tumor tissues and provide information to better understand UM biology.

Abstract

Uveal melanoma (UM) is the most common primary intraocular malignant tumor in adults, showing a high mortality due to metastasis. Although it is considered a rare disease, a growing number of papers have reported altered levels of RNAs (i.e., coding and non-coding RNAs) in cancerous tissues and biological fluids from UM patients. The presence of circulating RNAs, whose dysregulation is associated with UM, paved the way to the possibility of exploiting it for diagnostic and prognostic purposes. However, the biological meaning and the origin of such RNAs in blood and ocular fluids of UM patients remain unexplored. In this review, we report the state of the art of circulating RNAs in UM and debate whether the amount and types of RNAs measured in bodily fluids mirror the RNA alterations from source cancer cells. Based on literature data, extracellular RNAs in UM patients do not represent, with rare exceptions, a snapshot of RNA dysregulations occurring in cancerous tissues, but rather the complex and heterogeneous outcome of a systemic dysfunction, including immune system activity, that modifies the mechanisms of RNA delivery from several cell types.

Influence of GAS5/MicroRNA-223-3p/P2Y12 Axis on Clopidogrel Response in Coronary Artery Disease

Background Dual antiplatelet therapy based on aspirin and P2Y12 receptor antagonists such as clopidogrel is currently the primary treatment for coronary artery disease (CAD). However, a percentage of patients exhibit clopidogrel resistance, in which genetic factors play vital roles. This study aimed to investigate the roles of GAS5 (growth arrest-specific 5) and its rs55829688 polymorphism in clopidogrel response in patients with CAD. Methods and Results A total of 444 patients with CAD receiving dual antiplatelet therapy from 2017 to 2018 were enrolled to evaluate the effect of GAS5 single nucleotide polymorphism rs55829688 on platelet reactivity index. Platelets from 37 patients of these patients were purified with microbeads to detect GAS5 and microRNA-223-3p (miR-223-3p) expression. Platelet-rich plasma was isolated from another 17 healthy volunteers and 46 newly diagnosed patients with CAD to detect GAS5 and miR-223-3p expression. A dual-luciferase reporter assay was performed to explore the interaction between miR-223-3p and GAS5 or P2Y12 3'-UTR in (human embryonic kidney 293 cell line that expresses a mutant version of the SV40 large T antigen) HEK 293T and (megakaryoblastic cell line derived in 1983 from the bone marrow of a chronic myeloid leukemia patient with megakaryoblastic crisis) MEG-01 cells. Loss-of-function and gain-of-function experiments were performed to reveal the regulation of GAS5 toward P2Y12 via miR-223-3p in MEG-01 cells. We observed that rs55829688 CC homozygotes showed significantly decreased platelet reactivity index than TT homozygotes in CYP2C19 poor metabolizers. Platelet GAS5 expression correlated positively with both platelet reactivity index and P2Y12 mRNA expressions, whereas platelet miR-223-3p expression negatively correlated with platelet reactivity index. Meanwhile, a negative correlation between GAS5 and miR-223-3p expressions was observed in platelets. MiR-223-3p mimic reduced while the miR-223-3p inhibitor increased the expression of GAS5 and P2Y12 in MEG-01 cells. Knockdown of GAS5 by siRNA increased miR-223-3p expression and decreased P2Y12 expression, which could be reversed by the miR-223-3p inhibitor. Meanwhile, overexpression of GAS5 reduced miR-223-3p expression and increased P2Y12 expression, which could be reversed by miR-223-3p mimic. Conclusions GAS5 rs55829688 polymorphism might affect clopidogrel response in patients with CAD with the CYP2C19 poor metabolizer genotypes, and GAS5 regulates P2Y12 expression and clopidogrel response by acting as a competitive endogenous RNA for miR-223-3p.

Knockdown of long noncoding RNA growth arrest-specific transcript 5 regulates forkhead box O3 to inhibit lipopolysaccharide-induced human bronchial epithelial cell pyroptosis

Pyroptosis is a novel proinflammatory programmed cell death process. This study was designed to investigate the functional mechanisms of long noncoding RNA growth arrest-specific transcript 5 (lncRNA GAS5) on lipopolysaccharide (LPS)-induced human bronchial epithelial cell (HBEC) pyroptosis. LPS was used to induce pyroptosis in HBECs, followed by the detection of the expression of GAS5, forkhead box O3 (FOXO3), and nuclear factor E2-related factor 2/heme oxygenase 1 (Nrf2/HO-1) signaling pathway-related factors. Cell viability was evaluated using CCK-8 assay, lactate dehydrogenase (LDH) release was assessed by LDH assay kit and caspase-1 activity by flow cytometry. Furthermore, expression of NOD-like receptor family pyrin domain containing 3 and pyroptosis-related proteins was evaluated using Western blot analysis, while enzyme-linked immunosorbent assay was used to determine the levels of inflammatory factors. The interaction between GAS5 and FOXO3 was confirmed using bioinformatic prediction, RNA immunoprecipitation assay, RNA pull-down, and dual-luciferase reporter gene assay. Treatment of HBECs with LPS upregulated the expression of GAS5 and FOXO3, resulting in the inactivation of the Nrf2/HO-1 signaling pathway. On the other hand, inhibition of both GAS5 and FOXO3 promoted cell viability, reduced LDH release, pyroptosis, and inflammatory response in LPS-induced HBECs. Furthermore, FOXO3 could interact with GAS5, while FOXO3 overexpression reversed the inhibitory effect of GAS5 knockdown on cell pyroptosis. Thus, mechanistically, inhibition of FOXO3 activates the Nrf2/HO-1 pathway to suppress LPS-induced pyroptosis in HBECs. This study revealed that GAS5 knockdown attenuates FOXO3 expression thereby activating the Nrf2/HO-1 pathway to inhibit LPS-induced pyroptosis in HBECs. These findings may contribute to identifying novel targets that inhibit pyroptosis in HBECs.

The Role of LncRNAs in Uveal Melanoma

Uveal melanoma (UM) is an intraocular cancer tumor with high metastatic risk. It is considered a rare disease, but 90% of affected patients die within 15 years. Non-coding elements (ncRNAs) such as long non-coding RNAs (lncRNAs) have a crucial role in cellular homeostasis maintenance, taking part in many critical cellular pathways. Their deregulation, therefore, contributes to the induction of cancer and neurodegenerative and metabolic diseases. In cancer, lncRNAs are implicated in apoptosis evasion, proliferation, invasion, drug resistance, and other roles because they affect tumor suppressor genes and oncogenes. For these reasons, lncRNAs are promising targets in personalized medicine and can be used as biomarkers for diseases including UM.

Development of new therapeutic options for the treatment of uveal melanoma

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. Important cytogenetic and genetic risk factors for the development of UM include chromosome 3 monosomy, mutations in the guanine nucleotide-binding proteins GNAQ/GNA11, and loss of the BRACA1-associated protein 1 (BAP 1). Most primary UMs are treated conservatively with radiotherapy, but enucleation is necessary for large tumours. Despite the effectiveness of local control, up to 50% of UM patients develop metastasis for which there are no effective therapies. Attempts to utilise the targeted therapies that have been developed for the treatment of other cancers, including a range of signal transduction pathway inhibitors, have rarely produced significant outcomes in UM. Similarly, the application of immunotherapies that are effective in cutaneous melanoma to treat UM have also been disappointing. Other approaches that have been initiated involve proteasomal inhibitors and histone deacetylase inhibitors which are approved for the treatment of other cancers. Nevertheless, there have been occasional positive outcomes from these treatments in UM. Moreover, combination approaches in UM have also yielded some positive developments. It would be valuable to identify how to apply such therapies efficiently in UM, potentially via individualised tumour profiling. It would also be important to characterise UM tumours to differentiate the potential drivers of progression from those in other types of cancers. The recent identification of novel kinases and metastatic genes in UM tumours makes the development of new UM-specific treatments feasible.