Biomarkers in retinoblastoma

Recent progress in retinoblastoma: Pathogenesis, presentation, diagnosis and management

Retinoblastoma, the primary ocular malignancy in pediatric patients, poses a substantial threat to mortality without prompt and effective management. The prognosis for survival and preservation of visual acuity hinges upon the disease severity at the time of initial diagnosis. Notably, retinoblastoma has played a crucial role in unraveling the genetic foundations of oncogenesis. The process of tumorigenesis commonly begins with the occurrence of biallelic mutation in the RB1 tumor suppressor gene, which is then followed by a cascade of genetic and epigenetic alterations that correspond to the clinical stage and pathological features of the tumor. The RB1 gene, recognized as a tumor suppressor, encodes the retinoblastoma protein, which plays a vital role in governing cellular replication through interactions with E2F transcription factors and chromatin remodeling proteins. The diagnosis and treatment of retinoblastoma necessitate consideration of numerous factors, including disease staging, germline mutation status, family psychosocial factors, and the resources available within the institution. This review has systematically compiled and categorized the latest developments in the diagnosis and treatment of retinoblastoma which enhanced the quality of care for this pediatric malignancy.

Advancements in the diagnosis, prognosis, and treatment of retinoblastoma

Retinoblastoma (RB) is a prevalent primitive intraocular malignancy in children, particularly in those younger than age 3 years. RB is caused by mutations in the RB1 gene. In developing countries, mortality rates for this type of cancer are still high, whereas industrialized countries have achieved a survival rate of >95%-98%. Untreated, the condition can be fatal, underscoring the importance of early diagnosis. The existing treatments primarily consist of surgery, radiotherapy, and chemotherapy. The detrimental effects of radiation and chemotherapeutic drugs have been documented as factors that contribute to increased mortality rates and negatively affect the quality of life for patients. MicroRNA (miRNA), a type of noncoding RNA, exerts a substantial influence on RB development and the emergence of treatment resistance by regulating diverse cellular processes. This review highlights recent developments in the involvement of miRNAs in RB. This encompasses the clinical significance of miRNAs in the diagnosis, prognosis, and treatment of RB. Additionally, this paper examines the regulatory mechanisms of miRNAs in RB and explores potential therapeutic interventions. This paper provides an overview of the current and emerging treatment options for RB, focusing on recent studies investigating the application of different types of nanoparticles for the diagnosis and treatment of this condition.

Trefoil Family Factor Peptide 1-A New Biomarker in Liquid Biopsies of Retinoblastoma under Therapy

Effective management of retinoblastoma (RB), the most prevalent childhood eye cancer, depends on reliable monitoring and diagnosis. A promising candidate in this context is the secreted trefoil family factor peptide 1 (TFF1), recently discovered as a promising new biomarker in patients with a more advanced subtype of retinoblastoma. The present study investigated TFF1 expression within aqueous humor (AH) of enucleated eyes and compared TFF1 levels in AH and corresponding blood serum samples from RB patients undergoing intravitreal chemotherapy (IVC). TFF1 was consistently detectable in AH, confirming its potential as a biomarker. Crucially, our data confirmed that TFF1-secreting cells within the tumor mass originate from RB tumor cells, not from surrounding stromal cells. IVC-therapy-responsive patients exhibited remarkably reduced TFF1 levels post-therapy. By contrast, RB patients' blood serum displayed low-to-undetectable levels of TFF1 even after sample concentration and no therapy-dependent changes were observed. Our findings suggest that compared with blood serum, AH represents the more reliable source of TFF1 if used for liquid biopsy RB marker analysis in RB patients. Thus, analysis of TFF1 in AH of RB patients potentially provides a minimally invasive tool for monitoring RB therapy efficacy, suggesting its importance for effective treatment regimens.

Genetics in ophthalmology: molecular blueprints of retinoblastoma

This review presents current knowledge on the molecular biology of retinoblastoma (RB). Retinoblastoma is an intraocular tumor with hereditary and sporadic forms. 8,000 new cases of this ocular malignancy of the developing retina are diagnosed each year worldwide. The major gene responsible for retinoblastoma is RB1, and it harbors a large spectrum of pathogenic variants. Tumorigenesis begins with mutations that cause RB1 biallelic inactivation preventing the production of functional pRB proteins. Depending on the type of mutation the penetrance of RB is different. However, in small percent of tumors additional genes may be required, such as MYCN, BCOR and CREBBP. Additionally, epigenetic changes contribute to the progression of retinoblastoma as well. Besides its role in the cell cycle, pRB plays many additional roles, it regulates the nucleosome structure, participates in apoptosis, DNA replication, cellular senescence, differentiation, DNA repair and angiogenesis. Notably, pRB has an important role as a modulator of chromatin remodeling. In recent years high-throughput techniques are becoming essential for credible biomarker identification and patient management improvement. In spite of remarkable advances in retinoblastoma therapy, primarily in high-income countries, our understanding of retinoblastoma and its specific genetics still needs further clarification in order to predict the course of this disease and improve therapy. One such approach is the tumor free DNA that can be obtained from the anterior segment of the eye and be useful in diagnostics and prognostics.

Roles, biological functions, and clinical significances of RHPN1-AS1 in cancer

For the complex and multifaceted challenge of cancer eradication, a comprehensive approach is required. Molecular strategies are critical in the fight against cancer as they allow us to understand the underlying fundamental mechanisms and develop specialized treatments. The role of long non-coding RNAs (lncRNAs), a class of ncRNA molecules longer than 200 nucleotides, in cancer biology has attracted growing attention in recent years. These roles include but are not limited to regulating gene expression, protein localization, and chromatin remodeling. LncRNAs can influence a range of cellular functions and pathways, including those involved in cancer development. The first study on RHPN1 antisense RNA 1 (RHPN1-AS1), a 2030-bp transcript originating from human chromosome 8q24, in uveal melanoma (UM) demonstrated that this lncRNA was significantly upregulated in several UM cell lines. Further studies in various cancer cell lines showed that this lncRNA is significantly overexpressed and exerts oncogenic functions. This review will provide an overview of current knowledge regarding the roles played by RHPN1-AS1 in the emergence of various cancers, focusing on its biological and clinical functions.

miRNAs as potential game-changers in retinoblastoma: Future clinical and medicinal uses

Retinoblastoma (RB) is a rare tumor in children, but it is the most common primitive intraocular malignancy in childhood age, especially those below three years old. The RB gene (RB1) undergoes mutations in individuals with RB. Although mortality rates remain high in developing countries, the survival rate for this type of cancer is greater than 95-98% in industrialized countries. However, it is lethal if left untreated, so early diagnosis is essential. As a non-coding RNA, miRNA significantly impacts RB development and treatment resistance because it can control various cellular functions. In this review, we illustrate the recent advances in the role of miRNAs in RB. That includes the clinical importance of miRNAs in RB diagnosis, prognosis, and treatment. Moreover, the regulatory mechanisms of miRNAs in RB and therapeutic interventions are discussed.

The predictive capacity of in vitro preclinical models to evaluate drugs for the treatment of retinoblastoma

Retinoblastoma is a rare childhood cancer of the eye. Of the small number of drugs are used to treat retinoblastoma, all have been repurposed from drugs developed for other conditions. In order to find drugs or drug combinations better suited to the improved treatment of retinoblastoma, reliable predictive models are required, which facilitate the challenging transition from in vitro studies to clinical trials. In this review, the research performed to date on the development of 2D and 3D in vitro models for retinoblastoma is presented. Most of this research was undertaken with a view to better biological understanding of retinoblastoma, and we discuss the potential for these models to be applied to drug screening. Future research directions for streamlined drug discovery are considered and evaluated, and many promising avenues identified.

Zebrafish as an Orthotopic Tumor Model for Retinoblastoma Mimicking Routes of Human Metastasis

BACKGROUND

Retinoblastoma (RB) is the most common eye cancer in children that has a high mortality rate when left untreated. Mouse models for retinoblastoma have been established but are time- and cost-intensive. The aim of this work was to evaluate an orthotopic transplantation model of retinoblastoma in zebrafish that also allows for tracking migratory routes and to explore advantages and disadvantages with respect to drug testing.

METHODS

Three fluorescence-labeled retinoblastoma cell lines (RB355, WERI-RB-1, Y79) were injected into the left eye of two-day-old zebrafish, while the un-injected right eye served as control. The migratory trajectories of injected retinoblastoma cells were observed until 8 days post injection (dpi), both in lateral and dorsal view, and measuring fluorescence intensity of injected cells was done for RB355 cells.

RESULTS

Time until the onset of migration and routes for all three retinoblastoma cell lines were comparable and resulted in migration into the brain and ventricles of the forebrain, midbrain and hindbrain. Involvement of the optic nerve was observed in 10% of injections with the RB355 cell line, 15% with Y79 cells and 5% with WERI-RB-1 cells. Fluorescence intensity of injected RB355 cells showed an initial increase until five dpi, but then decreased with high variability until the end of observation.

CONCLUSION

The zebrafish eye is well suited for the analysis of migratory routes in retinoblastoma and closely mirrors patterns of retinoblastoma metastases in humans.

Genome maintenance in retinoblastoma: Implications for therapeutic vulnerabilities (Review)

Retinoblastoma (RB) is a pediatric ocular malignancy that is initiated mostly by biallelic inactivation of the RB transcriptional corepressor 1 (RB1) tumor suppressor gene in the developing retina. Unlike the prevailing prediction based on multiple studies involving RB1 gene disruption in experimental models, human RB tumors have been demonstrated to possess a relatively stable genome, characterized by a low mutation rate and a few recurrent chromosomal alterations related to somatic copy number changes. This suggests that RB may harbor heightened genome maintenance mechanisms to counteract or compensate for the risk of massive genome instability, which can potentially be driven by the early RB1 loss as a tumor-initiating event. Although the genome maintenance mechanisms might have been evolved to promote RB cell survival by preventing lethal genomic defects, emerging evidence suggests that the dependency of RB cells on these mechanisms also exposes their unique vulnerability to chemotherapy, particularly when the genome maintenance machineries are tumor cell-specific. This review summarizes the genome maintenance mechanisms identified in RB, including findings on the roles of chromatin regulators in DNA damage response/repair and protein factors involved in maintaining chromosome stability and promoting survival in RB. In addition, advantages and challenges for exploiting these therapeutic vulnerabilities in RB are discussed.

RING-Finger Protein 6 promotes Drug Resistance in Retinoblastoma via JAK2/STAT3 Signaling Pathway

Chemotherapy is the first-line treatment for human retinoblastoma (RB), but the occurrence of drug resistance greatly limited its efficacy in practice. RING-finger protein 6 (RNF6) is an E3 ubiquitin ligase that is aberrantly upregulated in a range of cancers and plays important roles in cancer progression. However, the role of RNF6 in RB is largely unknown. In this study, we investigated the role of RNF6 in RB drug resistance. Two carboplatin-resistant RB cells, Y-79/CR and SO-Rb50/CR, were generated based on Y-79 and SO-Rb50 cells. RT-PCR and western blot analyses showed that RNF6 expression on both mRNA and protein levels was significantly increased in Y-79/CR and SO-Rb50/CR cells comparing to their parental cells. Knockdown of RNF6 using siRNA in Y-79/CR and SO-Rb50/CR cells resulted in cells sensitive to carboplatin on a RNF6 siRNA dose dependent manner. Similarly, RNF6 overexpression in parental Y-79 and SO-Rb50 cells could help cells gain resistance to carboplatin on a RNF6 expression dependent manner. Signaling pathway analyses revealed that JAK2/STAT3 pathway was involved in the RNF6-induced carboplatin resistance in RB cells. We further revealed that RNF6 expression in both Y-79 and SO-Rb50 cells could render cells resistant to multiple anti-cancer drugs including carboplatin, vincristine and etoposide, an implication of RNF6 as a biomarker for RB drug resistance. Taken together, our study has revealed that RNF6 is upregulated in drug-resistant RB cells and RNF6 promotes drug resistance through JAK2/STAT3 signaling pathway. The importance of RNF6 in RB cells drug resistance may represent this protein as a potential biomarker and treatment target for drug resistance in RB.

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.

TRIB3 promotes proliferation, migration, and invasion of retinoblastoma cells by activating the AKT/mTOR signaling pathway

BACKGROUND

Tribbles pseudokinase 3 (TRIB3) is a member of the tribbles-related family, which has been determined in various cancers, including renal cell carcinoma, acute promyelocytic leukemia, colorectal cancer, endometrial cancer, and glioma. However, its role in retinoblastoma (RB) has not yet been explored.

METHODS

The expression level of TRIB3 was detected in RB tissues and cell lines using qRT-PCR. The effects of TRIB3 on cell proliferation and invasion capacities were analyzed with MTT, crystal violet, and transwell assays. Western blot and rescue assays were conducted to explore the underlying mechanism.

RESULTS

This study found that TRIB3 was upregulated in human RB tissues compared to adjacent normal tissues both at the mRNA and protein levels. Overexpression of TRIB3 significantly promoted cell proliferation and invasion of RB cells, while TRIB3 knockdown inhibited these processes. Moreover, the mechanism deciphering experiments showed that TRIB3 overexpression can increase AKT and mTOR phosphorylation. Conversely, TRIB3 knockdown decreased the phosphorylation of AKT and mTOR. Additionally, MK2206, a potent AKT inhibitor, blocked the promotive effects of TRIB3 in RB cells.

CONCLUSION

This study demonstrated that TRIB3 acts as an oncogene and plays a crucial role in the proliferation and invasion of RB cells via regulating the AKT/mTOR signaling pathway. Therefore, TRIB3 may serve as a potential target in the diagnosis and/or treatment of RB.

Lupeol induces autophagy and apoptosis with reduced cancer stem-like properties in retinoblastoma via phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin inhibition

OBJECTIVES

To evaluate the anticancer effects of lupeol in retinoblastoma cells.

METHODS

WERI-Rb-1 and Y-79 cell lines were used to evaluate the anticancer effect of lupeol. After lupeol treatment, the viability, proliferation, apoptosis, cancer stem-like properties, autophagy and in vivo tumour xenograft formation were detected.

KEY FINDINGS

In this study, lupeol decreased cell viability in both WERI-Rb-1 and Y-79 cell lines. Lupeol could also inhibit proliferation and induce apoptosis of RB cells, with increased Bax level and decreased Ki67, survivin and Bcl-2 levels. Furthermore, lupeol could suppress the spheroid formation and stem-like properties of RB cells. Moreover, LC3 II/LC3 I ratio and the levels of Beclin1 and ATG7 were increased after lupeol treatment, indicating that lupeol could induce autophagy in RB cells. Next, the inhibitory effect of lupeol on the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin pathway was observed. In tumour-bearing mice, lupeol suppressed tumour growth, and this might relate to its role in cell apoptosis, autophagy and stem-like properties.

CONCLUSIONS

Lupeol suppressed proliferation and cancer stem-like properties, and promoted autophagy and apoptosis of RB cells by restraining the PI3K/AKT/mTOR pathway.

The Impact of Cell-Free DNA Analysis on the Management of Retinoblastoma

Retinoblastoma is a childhood eye cancer, mainly caused by mutations in the RB1 gene, which can be somatic or constitutional. Unlike many other cancers, tumour biopsies are not performed due to the risk of tumour dissemination. As a result, until recently, somatic genetic analysis was only possible if an affected eye was removed as part of a treatment. Several recent proof of principle studies have demonstrated that the analysis of tumour-derived cell-free DNA, either obtained from ocular fluid or blood plasma, has the potential to advance the diagnosis and influence the prognosis of retinoblastoma patients. It has been shown that a confirmed diagnosis is possible in retinoblastoma patients undergoing conservative treatment. In vivo genetic analysis of retinoblastoma tumours is also now possible, allowing the potential identification of secondary genetic events as prognostic biomarkers. In addition, noninvasive prenatal diagnosis in children at risk of inheriting retinoblastoma has been developed. Here, we review the current literature and discuss the potential impact of cell-free DNA analysis on both the diagnosis and treatment of retinoblastoma patients and their families.

Multi-Functionalized Nanomaterials and Nanoparticles for Diagnosis and Treatment of Retinoblastoma

Retinoblastoma is a rare type of cancer, and its treatment, as well as diagnosis, is challenging, owing to mutations in the tumor-suppressor genes and lack of targeted, efficient, cost-effective therapy, exhibiting a significant need for novel approaches to address these concerns. For this purpose, nanotechnology has revolutionized the field of medicine with versatile potential capabilities for both the diagnosis, as well as the treatment, of retinoblastoma via the targeted and controlled delivery of anticancer drugs via binding to the overexpressed retinoblastoma gene. Nanotechnology has also generated massive advancements in the treatment of retinoblastoma based on the use of surface-tailored multi-functionalized nanocarriers; overexpressed receptor-based nanocarriers ligands (folate, galactose, and hyaluronic acid); lipid-based nanocarriers; and metallic nanocarriers. These nanocarriers seem to benchmark in mitigating a plethora of malignant retinoblastoma via targeted delivery at a specified site, resulting in programmed apoptosis in cancer cells. The effectiveness of these nanoplatforms in diagnosing and treating intraocular cancers such as retinoblastoma has not been properly discussed, despite the increasing significance of nanomedicine in cancer management. This article reviewed the recent milestones and future development areas in the field of intraocular drug delivery and diagnostic platforms focused on nanotechnology.

Liquid Biopsy for Solid Ophthalmic Malignancies: An Updated Review and Perspectives

Simple Summary

To date, there is no treatment for metastatic uveal melanoma. Identifying its metastatic spread is essential. Liquid biopsy can identify patients at risk of metastatic spread early. Here, we aim to summarize the current knowledge of liquid biopsy in ophthalmic malignant tumors, including uveal melanoma. Our objective is to establish the current state of liquid biopsy in the ophthalmic field, as well as its perspectives and limitations.

Abstract

Tissue biopsy is considered the gold standard when establishing a diagnosis of cancer. However, tissue biopsies of intraocular ophthalmic malignancies are hard to collect and are thought to be associated with a non-negligible risk of extraocular dissemination. Recently, the liquid biopsy (LB) has emerged as a viable, non-invasive, repeatable, and promising way of obtaining a diagnosis, prognosis, and theragnosis of patients with solid tumors. LB refers to blood, as well as any human liquid. The natural history of uveal melanoma (UM) and retinoblastoma (RB) are radically opposed. On the one hand, UM is known to disseminate through the bloodstream, and is, therefore, more accessible to systemic venous liquid biopsy. On the other hand, RB rarely disseminates hematogenous, and is, therefore, more accessible to local liquid biopsy by performing an anterior chamber puncture. In this review, we summarize the current knowledge concerning LB in UM, RB, conjunctival tumors, and choroidal metastases. We also develop the current limitations encountered, as well as the perspectives.

Analysis of the p53 pathway in peripheral blood of retinoblastoma patients; potential biomarkers

Loss of retinoblastoma (RB) function in the cone cells during retina development is necessary but not sufficient for retinoblastoma development. It has been reported that in the absence of RB activity, a retinoma is generated, and the onset of retina cancer occurs until the p53 pathway is altered. Unlike other types of cancer, in retinoblastoma the p53 tumour suppressor is mostly wild type, although its two primary regulators, MDMX and MDM2, are commonly dysregulated. A mutated RB form is inherited in around 35% of the cases, but normally two, somatic mutations are needed to alter the RB function. Here we investigated the mRNA levels of RB, p53, MDMX and MDM2 in peripheral blood samples of retinoblastoma patients to monitor the pathway status of p53 in somatic cells. We sought to investigate the involvement of these genes in the development of retina cancer, with the aim of identifying biomarkers for early diagnosis of this disease.