Distinct Gene Expression Profiles Define Anaplastic Grade in Retinoblastoma

Correlation of gene expression with magnetic resonance imaging features of retinoblastoma: a multi-center radiogenomics validation study

OBJECTIVES

To validate associations between MRI features and gene expression profiles in retinoblastoma, thereby evaluating the repeatability of radiogenomics in retinoblastoma.

METHODS

In this retrospective multicenter cohort study, retinoblastoma patients with gene expression data and MRI were included. MRI features (scored blinded for clinical data) and matched genome-wide gene expression data were used to perform radiogenomic analysis. Expression data from each center were first separately processed and analyzed. The end product normalized expression values from different sites were subsequently merged by their Z-score to permit cross-sites validation analysis. The MRI features were non-parametrically correlated with expression of photoreceptorness (radiogenomic analysis), a gene expression signature informing on disease progression. Outcomes were compared to outcomes in a previous described cohort.

RESULTS

Thirty-six retinoblastoma patients were included, 15 were female (42%), and mean age was 24 (SD 18) months. Similar to the prior evaluation, this validation study showed that low photoreceptorness gene expression was associated with advanced stage imaging features. Validated imaging features associated with low photoreceptorness were multifocality, a tumor encompassing the entire retina or entire globe, and a diffuse growth pattern (all p < 0.05). There were a number of radiogenomic associations that were also not validated.

CONCLUSIONS

A part of the radiogenomic associations could not be validated, underlining the importance of validation studies. Nevertheless, cross-center validation of imaging features associated with photoreceptorness gene expression highlighted the capability radiogenomics to non-invasively inform on molecular subtypes in retinoblastoma.

CLINICAL RELEVANCE STATEMENT

Radiogenomics may serve as a surrogate for molecular subtyping based on histopathology material in an era of eye-sparing retinoblastoma treatment strategies.

KEY POINTS

• Since retinoblastoma is increasingly treated using eye-sparing methods, MRI features informing on molecular subtypes that do not rely on histopathology material are important. • A part of the associations between retinoblastoma MRI features and gene expression profiles (radiogenomics) were validated. • Radiogenomics could be a non-invasive technique providing information on the molecular make-up of retinoblastoma.

Nitric oxide suppression by secreted frizzled-related protein 2 drives retinoblastoma

Retinoblastoma is a cancer of the infant retina primarily driven by loss of the Rb tumor suppressor gene, which is undruggable. Here, we report an autocrine signaling, mediated by secreted frizzled-related protein 2 (SFRP2), which suppresses nitric oxide and enables retinoblastoma growth. We show that coxsackievirus and adenovirus receptor (CXADR) is the cell-surface receptor for SFRP2 in retinoblastoma cells; that CXADR functions as a "dependence receptor," transmitting a growth-inhibitory signal in the absence of SFRP2; and that the balance between SFRP2 and CXADR determines nitric oxide production. Accordingly, high SFRP2 RNA expression correlates with high-risk histopathologic features in retinoblastoma. Targeting SFRP2 signaling by SFRP2-binding peptides or by a pharmacological inhibitor rapidly induces nitric oxide and profoundly inhibits retinoblastoma growth in orthotopic xenograft models. These results reveal a cytokine signaling pathway that regulates nitric oxide production and retinoblastoma cell proliferation and is amenable to therapeutic intervention.

Development and characterization of DNA aptamer against Retinoblastoma by Cell-SELEX

Retinoblastoma (RB) is the most common paediatric intraocular tumour. The management of RB has improved the survival and vision with recent advances in the treatment. Improved therapeutic approaches focussing on targeting tumours and minimizing the treatment-associated side effects are being developed. In this study, we generated a ssDNA aptamer against RB by cell-SELEX and high-throughput sequencing using Weri-RB1 cell line as the target, and Muller glial cell line Mio-M1 as the control. Three aptamers were selected based on the number of repetitions in NGS and phylogenetic relationship and evaluated by flow cytometry to assess their binding affinity and selectivity. The dissociation constant, Kd values of three selected aptamers were found to be in the nanomolar range. Aptamer VRF-CSRB-01 with the best binding affinity and a Kd value of 49.41 ± 7.87 nM was further characterized. The proteinase and temperature treatment indicated that VRF-CSRB-01 targets surface proteins, and has a good binding affinity and excellent selectivity under physiological conditions. The aptamer VRF-CSRB-01 was stable over 72 h in serum and 96 h in cerebral spinal fluid and vitreous. With the high affinity, specificity, stability and specific recognition of clinical RB tumours, VRF-CSRB-01 aptamer holds potential for application in diagnosis and targeting RB.

UBE2T/STAT3 Signaling Promotes the Proliferation and Tumorigenesis in Retinoblastoma

Purpose

The purpose of this paper was to investigate the expression and function of Ubiquitin-conjugating enzyme 2T (UBE2T), a human E2 ubiquitin-conjugating enzyme, in human retinoblastoma.

Methods

The expression of UBE2T in normal retina and retinoblastoma was analyzed using the Gene Expression Omnibus (GEO) databases, and its expression was immunohistochemically evaluated in 29 retinoblastoma sections and 5 normal retinas. Then CCK-8, flow cytometry, RNA-sequencing analysis, and in vivo assays were performed to explore the exact role of UBE2T in retinoblastoma.

Results

We found that retinoblastoma showed higher UBE2T expression than normal retina in GEO datasets and tissues. The immunoreactive score of UBE2T ≥4 was associated with group E in IIRC, T2-T4b in pTNM staging, poorly differentiated retinoblastoma, and high-risk histopathological factors. Knockdown of UBE2T reduced the cell viability, increased the apoptosis cells and G0/G1 cells, and inhibited subcutaneous tumor growth in vivo. Mechanistic studies showed that UBE2T knockdown induced down-regulation of phosphorylation of STAT3 and its downstream genes in vitro and in vivo. Rescue assays confirmed that STAT3 signaling pathway was involved in the effect of reduced cell viability, elevated apoptosis cells, and G0/G1 cells mediated by UBE2T knockdown.

Conclusions

Our data indicate that UBE2T significantly participates in the proliferation of retinoblastoma via the STAT3 signaling pathway, suggesting the potential of UBE2T as a therapeutic target for retinoblastoma treatment.

UBE2T is a prognostic biomarker and correlated with Th2 cell infiltrates in retinoblastoma

OBJECTIVE

This study aimed to screen anaplasia-related genes that influence the progression of retinoblastoma (RB) and to identify immune cells associated with the poor prognosis.

METHODS

Differentially expressed genes (DEGs) between retina and RB samples were acquired from gene expression omnibus (GEO) database. Candidate hub genes were screened by taking intersections among the co-expressed genes, the hub nodes, and DEGs of the validation set. The hub genes were identified by receiver operating characteristic (ROC) and quantitative real-time PCR (qPCR). Immune infiltration levels of RB tissues were estimated using single-sample gene set enrichment analysis (ssGSEA). The functions of RB cells were detected by CCK8, EDU and flow cytometry assays.

RESULTS

665 DEGs involved in the genesis and progression of RB were acquired from GEO database. 29 candidate hub genes were screened by examining 43 co-expressed genes and 63 hub nodes. 9 hub genes (CHEK1, EXO1, FANCI, GTSE1, MELK, MKI67, NCAPH, PRC1, and UBE2T) strongly related to the anaplastic grades were validated by ROC curve analysis (AUC >0.8). Based on the ssGSEA scores, the immune infiltration levels of Th2 cells were positively associated with anaplastic grade. qPCR assay showed that 9 hub genes were upregulated in RB cells, and UBE2T expressed remarkably high. CCK 8, EDU, and flow cytometry assays revealed that UBE2T silencing inhibited the proliferation of RB cells and incited apoptosis.

CONCLUSIONS

The increased infiltration of Th2 cells and upregulated expression of 9 hub genes predict a poor prognosis of RB. UBE2T can be a therapeutic target for RB treatment.

Identification of Epigenetically Modified Hub Genes and Altered Pathways Associated With Retinoblastoma

Retinoblastoma (Rb) is the most common childhood malignancy initiated by biallelic mutation in RB1 gene and driven by various epigenetic events including DNA methylation and microRNA dysregulation. Hence, understanding the key genes that are critically modulated by epigenetic modifications in RB1^−/− cells is very important to identify prominent biomarkers and therapeutic targets of Rb. In this study, we for the first time have integrated various Rb microarray NCBI-GEO datasets including DNA Methylation (GSE57362), miRNA (GSE7072) and mRNA (GSE110811) to comprehensively investigate the epigenetic consequences of RB loss in retinoblastoma tumors and identify genes with the potential to serve as early diagnostic markers and therapeutic targets for Rb. Interestingly, the GEO2R and co-expression network analysis have identified three genes namely E2F3, ESR1, and UNC5D that are significantly deregulated by modified DNA methylation, mRNA and microRNA expression in Rb tumors. Due to their recognition in all epigenetic, transcriptomic, and miRNA datasets, we have termed these genes as “common genes”. The results of our integrative bioinformatics analysis were validated in vitro by studying the gene and protein expression of these common genes in Y79, WERI-Rb-1, Rb cell lines and non-tumorigenic retinal pigment epithelial cell line (hTERT-RPE). The expression of E2F3 and UNC5D were up-regulated and that of ESR1 was down-regulated in Rb tumor cells when compared to that in non-tumorigenic hTERT-RPE cells. More importantly, UNC5D, a potent tumor suppressor gene in most cancers is significantly up-regulated in Y79 and Weri Rb1 cells, which, in turn, questions its anti-cancer properties. Together, our study shows that E2F3, ESR1, and UNC5D may be crucially involved in Rb tumorigenesis and possess the potential to act as early diagnostic biomarkers and therapeutic targets of Rb.

Survival outcomes of unilateral retinoblastoma based on pathological risk stratification-experience at a tertiary care centre in Pakistan

Retinoblastoma (RB) is the most common childhood intraocular malignancy. In high-income countries over the past decade, upfront enucleation for unilateral RB is least favoured due to other alternatives that can help in globe preservation, but in low-middle income countries it is still the preferred option due to lack of resources and expertise. The treatment of RB after enucleation is tailored based on the histopathological risk features, as adjuvant chemotherapy with high-risk features reduces the risk of metastasis. The aim of our study was to analyse the survival outcomes of adjuvant therapy based on histopathological risk stratification in patients who underwent upfront enucleation for unilateral RB with advanced disease. A retrospective study was carried out at Shaukat Khanum Memorial Cancer Hospital and Research Centre, Pakistan. A total 113 patients (aged 3 months till 16 years) diagnosed with unilateral RB who had upfront enucleation from July 2009 till January 2019 were included in this study. The mean age of diagnosis was 37.4 months (±24.5) and male-to-female ratio of 1.3:1. The most common clinical presentation was leukocoria (74.3%). Patients who underwent enucleation had advanced disease; group D present in 62.8% followed by group E (32.7%). Histopathology revealed high-risk features in 29 patients (25.7%) and intermediate risk in 54 patients (47.8%). Disease progression and relapse was seen in patients with high-risk histopathological features. The 4-year over-all survival and EFS observed for this cohort was 74% and 71%. Awareness about the early symptoms among the general population and health care personnel at a nationwide level is needed to facilitate early detection and lessen disease related morbidity and mortality.

Gain of Chromosome 6p Correlates with Severe Anaplasia, Cellular Hyperchromasia, and Extraocular Spread of Retinoblastoma

PURPOSE

Gain of chromosome 6p has been associated with poor ocular survival in retinoblastoma and histopathologic grading of anaplasia with increased risk of metastatic spread and death. This study examined the correlation between these factors and other chromosomal abnormalities as well as results of whole genome sequencing, digital morphometry, and progression-free survival.

DESIGN

Retrospective cohort study from 2 United States tertiary referral centers.

PARTICIPANTS

Forty-two children who had undergone enucleation for retinoblastoma from January 2000 through December 2017.

METHODS

Status of chromosomes 6p, 1q, 9q, and 16q was evaluated with fluorescence in situ hybridization, the degree of anaplasia and presence of histologic high-risk features were assessed by ocular pathologists, digital morphometry was performed on scanned tumor slides, and whole genome sequencing was performed on a subset of tumors. Progression-free survival was defined as absence of distant or local metastases or tumor growth beyond the cut end of the optic nerve.

MAIN OUTCOME MEASURES

Correlation between each of chromosomal abnormalities, anaplasia, morphometry and sequencing results, and survival.

RESULTS

Forty-one of 42 included patients underwent primary enucleation and 1 was treated first with intra-arterial chemotherapy. Seven tumors showed mild anaplasia, 19 showed moderate anaplasia, and 16 showed severe anaplasia. All tumors had gain of 1q, 18 tumors had gain of 6p, 6 tumors had gain of 9q, and 36 tumors had loss of 16q. Tumors with severe anaplasia were significantly more likely to harbor 6p gains than tumors with nonsevere anaplasia (P < 0.001). Further, the hematoxylin staining intensity was significantly greater and that of eosin staining significantly lower in tumors with severe anaplasia (P < 0.05). Neither severe anaplasia (P = 0.10) nor gain of 6p (P = 0.21) correlated with histologic high-risk features, and severe anaplasia did not correlate to RB1, CREBBP, NSD1, or BCOR mutations in a subset of 14 tumors (P > 0.5). Patients with gain of 6p showed significantly shorter progression-free survival (P = 0.03, Wilcoxon test).

CONCLUSIONS

Gain of chromosome 6p emerges as a strong prognostic biomarker in retinoblastoma because it correlates with severe anaplasia, quantifiable changes in tumor cell staining characteristics, and extraocular spread.

Centromere protein E as a novel biomarker and potential therapeutic target for retinoblastoma

Retinoblastoma is the most common intraocular malignancy during childhood. Currently, there is no effective treatment for metastatic retinoblastoma. We investigated potential biomarkers of retinoblastoma by utilizing three datasets from a public database. Functional enrichment analysis, including gene ontology, Kyoto encyclopedia of genes and genomes, gene set enrichment analysis and variation analysis, suggested that differentially expressed genes in retinoblastoma were enriched in accelerated cell cycle events. Protein-protein interaction analysis constructed a network consisting of six hub genes, including benzimidazoles 1 (BUB1), cyclin dependent kinase 1 (CDK1), centromere protein E (CENPE), kinesin family member 20A (KIF20A), PDZ binding kinase (PBK), and targeting protein for xklp2 (TPX2). Drug sensitivity analysis showed that nelarabine was positively correlated with five hub genes. All six genes were expressed differently in six immune subtypes and were positively correlated with stemness indices in most human cancer types. Since CENPE is the least known hub gene in retinoblastoma, we further analyzed the potential non-coding RNAs and transcription factors that regulate CENPE and built interaction networks of competing endogenous RNA and transcription factors. Immune cell infiltration, especially by plasma and B cells, was enhanced in samples with high CENPE expression. Pan-cancer analysis illustrated that CENPE was highly expressed in a wide range of human tumors. In vitro validation revealed that CENPE was significantly upregulated at both the mRNA and protein levels in retinoblastoma cells. In conclusion, CENPE, along with other hub genes, could serve as a potential biomarker and intervention target for retinoblastoma.

Weighted genes associated with the progression of retinoblastoma: Evidence from bioinformatic analysis

Mechanisms underlying the development of malignant retinoblastoma (RB) remain largely unknown. The purpose of this study was to identify weighted genes that are associated with the progression of RB and to assess the usefulness of bioinformatic analysis in RB research. Bioinformatic analysis was performed to construct weighted gene co-expression and protein-protein interaction (PPI) networks and to predict long non-coding RNA (lncRNA)-microRNA (miRNA)-mRNA regulatory networks. RNA extracted from RB and adjacent retinal tissue was used to validate the results obtained from bioinformatic analysis, using a semi-quantitative PCR (qPCR) assay. Twenty-one modules were generated from 5000 most variably expressed genes. Both the light-yellow and red modules were significantly associated with the cellular anaplastic grade of RB. The genes clustered in the light-yellow module included protocadherin beta (PCDHBs) family members. The red module included 5 hub genes involved in cell division. According to the hypothesis that lncRNA may serve as a competing endogenous RNA (ceRNA) for miRNAs and modulates mRNA expression, a network was constructed between lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) and cell division-related mRNAs. PCR analysis using 23 tumor tissues and 5 adjacent retinal tissue showed increased expression of PCDHB5 in tumor samples, and supported the predicted upregulation of mitotic checkpoint serine/threonine kinase (BUB1) by MALAT1 via miR-495-3p. Our study highlights the importance of bioinformatic analysis in identifying potential markers and mechanisms associated with the malignant transformation of RB, and provides evidence to suggest that PCDHB5 and the ceRNA regulatory network of MALAT1/miR-495-3p/BUB1 are involved in the progression of RB.

miR-340 Promotes Retinoblastoma Cell Proliferation, Migration and Invasion Through Targeting WIF1

Background

MicroRNAs (miRNAs) function as important regulators of gene expression involved in tumor pathogenesis, including retinoblastoma. However, the expression profiles and potential roles in retinoblastoma are still largely unclear.

Material and Methods

Differentially expressed miRNAs (DEmiRs) and genes (DEGs) in retinoblastoma were extracted from Gene Expression Omnibus (GEO) repository. Expression levels of miR-340 and WIF1 were detected in retinoblastoma tissues and cell lines by qRT-PCR. Both gain-of-function and loss-of-function experiments were performed to explore the effects of miR-340 on cell proliferation, migration and invasion. Bioinformatics analysis and luciferase reporter assay were used to explore the interaction between miR-340 and WIF1.

Results

A total of 11 DEmiRs were identified in retinoblastoma tissue and blood samples. Among them, we validated that miR-340 was the most highly expressed miRNA and correlated with tumor size, ICRB stage and optic nerve invasion. miR-340 was observed to enhance the proliferation, migration and invasion capacity of retinoblastoma cells. We then identified 26 DEGs from 3 retinoblastoma GEO datasets and subsequently constructed a miRNA–mRNA regulatory network. Further analysis revealed that WIF1 was a direct target of miR-340. Moreover, overexpression of WIF1 could repress retinoblastoma progression induced by miR-340 in vitro and in vivo.

Conclusion

Collectively, miR-340 functioned as an oncomiRNA to promote retinoblastoma cell proliferation, migration and invasion via regulating WIF1. Our data also provided multiple miRNAs and genes that may contribute to a better understanding of retinoblastoma pathogenesis.

TRIM59 Promotes Retinoblastoma Progression by Activating the p38-MAPK Signaling Pathway

Purpose

Retinoblastoma is a malignant tumor of the developing retina that mostly occurs in children. Our study aimed to investigate the effect of tripartite motif-containing protein 59 (TRIM59) on retinoblastoma growth and the underlying mechanisms.

Methods

We performed bioinformatic analysis of three datasets (GSE24673, GSE97508, and GSE110811) from the Gene Expression Omnibus database. Quantitative reverse-transcription PCR and immunoblotting of three retinoblastoma cell lines were conducted to verify TRIM59 as a differentially expressed gene. Specific siRNAs were used to inhibit TRIM59 expression in the HXO-Rb44 cell line. A lentiviral vector was transfected into the Y79 cell line to overexpress TRIM59. The effects of TRIM59 on retinoblastoma cell proliferation, cell cycling, and apoptosis were explored in vitro using the abovementioned cell lines. The effect of TRIM59 expression on retinoblastoma cell proliferation was evaluated in a mouse xenograft tumor model.

Results

TRIM59 expression in three retinoblastoma cell lines was remarkably elevated compared with normal control. Knocking down TRIM59 expression remarkably suppressed cell proliferation and growth and promoted cell apoptosis in HXO-Rb44 cells, whereas TRIM59 overexpression promoted tumor progression in Y79 cells. Silencing TRIM59 also markedly inhibited in vivo tumor growth in the xenograft model. Mechanistic studies revealed that TRIM59 upregulated phosphorylated p38, p-JNK1/2, p-ERK1/2, and p-c-JUN expression in retinoblastoma cells. Notably, the p38 inhibitor SB203580 attenuated the effects of TRIM59 on cell proliferation, apoptosis, and the G1/S phase transition.

Conclusions

TRIM59 plays an oncogenic role in retinoblastoma and exerts its tumor-promotive function by activating the p38-mitogen-activated protein kinase pathway.

Retinoblastoma: Etiology, Modeling, and Treatment

Retinoblastoma is a retinal cancer that is initiated in response to biallelic loss of RB1 in almost all cases, together with other genetic/epigenetic changes culminating in the development of cancer. RB1 deficiency makes the retinoblastoma cell-of-origin extremely susceptible to cancerous transformation, and the tumor cell-of-origin appears to depend on the developmental stage and species. These are important to establish reliable preclinical models to study the disease and develop therapies. Although retinoblastoma is the most curable pediatric cancer with a high survival rate, advanced tumors limit globe salvage and are often associated with high-risk histopathological features predictive of dissemination. The advent of chemotherapy has improved treatment outcomes, which is effective for globe preservation with new routes of targeted drug delivery. However, molecularly targeted therapeutics with more effectiveness and less toxicity are needed. Here, we review the current knowledge concerning retinoblastoma genesis with particular attention to the genomic and transcriptomic landscapes with correlations to clinicopathological characteristics, as well as the retinoblastoma cell-of-origin and current disease models. We further discuss current treatments, clinicopathological correlations, which assist in guiding treatment and may facilitate globe preservation, and finally we discuss targeted therapeutics for future treatments.

Identification of co‑expression modules and hub genes of retinoblastoma via co‑expression analysis and protein‑protein interaction networks

Retinoblastoma is a common intraocular malignant tumor in children. However, the molecular and genetic mechanisms of retinoblastoma remain unclear. The gene expression dataset GSE110811 was retrieved from Gene Expression Omnibus. After preprocessing, coexpression modules were constructed by weighted gene coexpression network analysis (WGCNA), and modules associated with clinical traits were identified. In addition, functional enrichment analysis was performed for genes in the indicated modules, and protein-protein interaction (PPI) networks and subnetworks were constructed based on these genes. Eight coexpression modules were constructed through WGCNA. Of these, the yellow module had the highest association with severity and age (r=0.82 and P=3e-07; r=0.72 and P=3e-05). The turquoise module had the highest association with months (r=−0.63 and P=5e-04). The genes in the two modules participate in multiple pathways of retinoblastoma, and by combining the PPI network and subnetworks; 10 hub genes were identified in the two modules. The present study identified coexpression modules and hub genes associated with clinical traits of retinoblastoma, providing novel insight into retinoblastoma progression.

Biomarkers in retinoblastoma

Retinoblastoma (RB) is the most common intraocular malignancy of childhood caused by inactivation of the Rb genes. The prognosis of RB is better with an earlier diagnosis. Many diagnostic approaches and appropriate clinical treatments have been developed to improve clinical outcomes. However, limitations exist when utilizing current methods. Recently, many studies have identified identify new RB biomarkers which can be used in diagnosis, as prognostic indicators and may contribute to understanding the pathogenesis of RB and help determine specific treatment strategies. This review focuses on recent advances in the discovery of RB biomarkers and discusses their clinical utility and challenges from areas such as epigenetics, proteomics and radiogenomics.

Conservative management of retinoblastoma: Challenging orthodoxy without compromising the state of metastatic grace. "Alive, with good vision and no comorbidity"

Retinoblastoma is lethal by metastasis if left untreated, so the primary goal of therapy is to preserve life, with ocular survival, visual preservation and quality of life as secondary aims. Historically, enucleation was the first successful therapeutic approach to decrease mortality, followed over 100 years ago by the first eye salvage attempts with radiotherapy. This led to the empiric delineation of a window for conservative management subject to a "state of metastatic grace" never to be violated. Over the last two decades, conservative management of retinoblastoma witnessed an impressive acceleration of improvements, culminating in two major paradigm shifts in therapeutic strategy. Firstly, the introduction of systemic chemotherapy and focal treatments in the late 1990s enabled radiotherapy to be progressively abandoned. Around 10 years later, the advent of chemotherapy in situ, with the capitalization of new routes of targeted drug delivery, namely intra-arterial, intravitreal and now intracameral injections, allowed significant increase in eye preservation rate, definitive eradication of radiotherapy and reduction of systemic chemotherapy. Here we intend to review the relevant knowledge susceptible to improve the conservative management of retinoblastoma in compliance with the "state of metastatic grace", with particular attention to (i) reviewing how new imaging modalities impact the frontiers of conservative management, (ii) dissecting retinoblastoma genesis, growth patterns, and intraocular routes of tumor propagation, (iii) assessing major therapeutic changes and trends, (iv) proposing a classification of relapsing retinoblastoma, (v) examining treatable/preventable disease-related or treatment-induced complications, and (vi) appraising new therapeutic targets and concepts, as well as liquid biopsy potentiality.