Chemotherapy in Retinoblastoma: Current Approaches

Pluripotent stem cell-derived models of retinal disease: Elucidating pathogenesis, evaluating novel treatments, and estimating toxicity

Blindness poses a growing global challenge, with approximately 26% of cases attributed to degenerative retinal diseases. While gene therapy, optogenetic tools, photosensitive switches, and retinal prostheses offer hope for vision restoration, these high-cost therapies will benefit few patients. Understanding retinal diseases is therefore key to advance effective treatments, requiring in vitro models replicating pathology and allowing quantitative assessments for drug discovery. Pluripotent stem cells (PSCs) provide a unique solution given their limitless supply and ability to differentiate into light-responsive retinal tissues encompassing all cell types. This review focuses on the history and current state of photoreceptor and retinal pigment epithelium (RPE) cell generation from PSCs. We explore the applications of this technology in disease modelling, experimental therapy testing, biomarker identification, and toxicity studies. We consider challenges in scalability, standardisation, and reproducibility, and stress the importance of incorporating vasculature and immune cells into retinal organoids. We advocate for high-throughput automation in data acquisition and analyses and underscore the value of advanced micro-physiological systems that fully capture the interactions between the neural retina, RPE, and choriocapillaris.

Retinoblastoma: A review of the molecular basis of tumor development and its clinical correlation in shaping future targeted treatment strategies

Retinoblastoma is a retinal cancer that affects children and is the most prevalent intraocular tumor worldwide. Despite tremendous breakthroughs in our understanding of the fundamental mechanisms that regulate progression of retinoblastoma, the development of targeted therapeutics for retinoblastoma has lagged. Our review highlights the current developments in the genetic, epigenetic, transcriptomic, and proteomic landscapes of retinoblastoma. We also discuss their clinical relevance and potential implications for future therapeutic development, with the aim to create a frontline multimodal therapy for retinoblastoma.

Targeted chemotherapy in retinoblastoma: A step forward from patient survival to globe survival

BACKGROUND/ OBJECTIVES

Despite being the most common intraocular malignancy in childhood, there is a substantial disparity between developing and developed countries in terms of patient and globe survival in retinoblastoma (Rb). The current study intends to determine patient and globe survival before and after the introduction of the new targeted treatment modalities in a developing country.

METHODS

Medical records of 350 patients (516 eyes) with retinoblastoma referred to a tertiary referral center for Rb in Tehran, Iran, were reviewed. In order to compare patient and globe survival before and after the availability of the new treatment modalities, including intra-arterial and intravitreal chemotherapy, the patients were divided into group 1 (2001-2007) and group 2 (2008-2018) based on the calendar period of diagnosis.

RESULTS

Two-hundred-twenty-three eyes of 149 patients and 293 eyes of 201 patients were categorized into groups 1 and 2, respectively. The 5-year patient survival was 97% across the current survey, and the overall survival rate was 96% in group 1 and 99% in group 2 (P = 0.08). Overall, 50% of eyes with retinoblastoma underwent enucleation, which was the primary in 63% (116/184) of the unilateral and 30% (99/322) of the bilateral cases. Primary enucleation was significantly lower in group 2 (35%) in contrast to group 1 (50%) (P < 0.001). In addition, globe survival improved significantly in the International Classification of Retinoblastoma Groups D (17% in group 1 vs. 66% in group 2, P < 0.001) and E (1% in group 1 vs. 23% in group 2 P < 0.001) during the two timelines. In enucleated eyes, despite the increased rate of prelaminar involvement in group 2 (13% vs. 2% in group 1, P = 0.003), the rate of high-risk histopathologic findings was similar between the two groups.

CONCLUSION

Similar to developed countries, the application of new targeted treatment modalities, including intra-arterial and intravitreal chemotherapy, has been associated with significantly improved globe survival in Rb patients. However, it should be noted that even with the availability of these novel treatment options, the decision for on-time enucleation should not be deferred.

Selective Induction of Intrinsic Apoptosis in Retinoblastoma Cells by Novel Cationic Antimicrobial Dodecapeptides

Host defense peptides represent an important component of innate immunity. In this work, we report the anticancer properties of a panel of hyper-charged wholly cationic antimicrobial dodecapeptides (CAPs) containing multiple canonical forms of lysine and arginine residues. These CAPs displayed excellent bactericidal activities against a broad range of pathogenic bacteria by dissipating the cytoplasmic membrane potential. Specifically, we identified two CAPs, named HC3 and HC5, that effectively killed a significant number of retinoblastoma (WERI-Rb1) cells (p ≤ 0.01). These two CAPs caused the shrinkage of WERI-Rb1 tumor spheroids (p ≤ 0.01), induced intrinsic apoptosis in WERI-Rb1 cells via activation of caspase 9 and caspase 3, cleaved the PARP protein, and triggered off the phosphorylation of p53 and γH2A.X. Combining HC3 or HC5 with the standard chemotherapeutic drug topotecan showed synergistic anti-cancer activities. Overall, these results suggest that HC3 and HC5 can be exploited as potential therapeutic agents in retinoblastoma as monotherapy or as adjunctive therapy to enhance the effectiveness of currently used treatment modalities.

Immunotherapies of retinoblastoma: Effective methods for preserving vision in the future

Retinoblastoma is the most common intraocular tumor in children. Patients can be cured by enucleation, but it can lead to vision loss. Chemotherapy is the main method of treatment for RB currently. Unfortunately, chemoresistant and tumor metastasis often happen, resulting in a relatively poor prognosis. Therefore, immunotherapy becomes one of the optimal choices. Targeting not only tumor cells but also the active tumor microenvironment is a novel strategy for RB treatment. Here, we conclude several potential targets for RB immunotherapy, including gangliosides GD2, PD-1 and PD-L1, B7H3, EpCAM and SYK. We also review the techniques for CART, bispecific antibodies and genetically modified Dendritic cells according to the characteristics of different targets and discuss the feasibility of immunotherapy with different targets.

Expression of Ki67 as detected by MIB-1 and its association with histopathological high-risk factors among patients with retinoblastoma tumour: a cross-sectional study

Objectives

This study aims to investigate the expression of Ki67 in formalin-fixed paraffin-embedded tissue blocks from patients with a diagnosis of retinoblastoma tumour (RbT) as well as determining its association with histopathological high-risk factors (HHRFs).

Methods and analysis

Retrospectively, a total of 194 eyeball specimens from 163 children with RbT were reviewed at Muhimbili National Hospital between 2009 and 2013. Immunohistochemical expression of Ki67 using MIB-1 antibody (Abcam, batch ab93680, Cambridge, UK) was determined and correlated with the conventional HHRFs. The predictors of Ki67 expression were determined using binary logistic regression model in multivariate analysis. A two-tailed p<0.05 was considered statistically significant.

Results

Majority (67.5%) of the patients had leukocoria and extraocular disease was found in 20.9% of all the patients. High expression of Ki67 was present in 63.8% of the 80 eyeballs that were tested. Massive choroidal invasion (adjusted OR (AOR)=9.32, 95% CI=2.82 to 10.89), positive retrolaminar optic nerve invasion (AOR=3.01, 95% CI=4.43 to 9.11), positive surgical margin (AOR=7.10, 95% CI=1.63 to 11.40) and pT4 (AOR=7.49, 95% CI=0.12 to 0.89) were the potential HHRFs that were associated with Ki67 overexpression.

Conclusion

Overexpression of Ki67 may be of prognostic value for patients with RbT as it has been shown in the present study that high expression was common in tumours with massive choroidal invasion, positive retrolaminar optic nerve invasion, positive surgical margin and advanced tumour stage, which are the conventional HHRFs associated with prognosis of RbT.

CircRNA-Associated CeRNAs Regulatory Axes in Retinoblastoma: A Systematic Scoping Review

Retinoblastoma (RB) is one of the most common childhood cancers caused by RB gene mutations (tumor suppressor gene in various patients). A better understanding of molecular pathways and the development of new diagnostic approaches may lead to better treatment for RB patients. The number of studies on ceRNA axes is increasing, emphasizing the significance of these axes in RB. Circular RNAs (circRNAs) play a vital role in competing endogenous RNA (ceRNA) regulatory axes by sponging microRNAs and regulating gene expression. Because of the broadness of ceRNA interaction networks, they may assist in investigating treatment targets in RB. This study conducted a systematic scoping review to evaluate verified loops of ceRNA in RB, focusing on the ceRNA axis and its relationship to circRNAs. This scoping review was carried out using a six-step strategy and the Prisma guideline, and it involved systematically searching the publications of seven databases. Out of 363 records, sixteen articles were entirely consistent with the defined inclusion criteria and were summarized in the relevant table. The majority of the studies focused on the circRNAs circ_0000527, circ_0000034, and circTET1, with approximately two-fifths of the studies focusing on a single circRNA. Understanding the many features of this regulatory structure may help elucidate RB’s unknown causative factors and provide novel molecular potential therapeutic targets and medical fields.

Downregulation of miR-211-5p Promotes Carboplatin Resistance in Human Retinoblastoma Y79 Cells by Affecting the GDNF-LIF Interaction

Purpose

To investigate the role of the miR-211-5p-GDNF signaling pathway in carboplatin resistance of retinoblastoma Y79 cells and what factors it may be affected by.

Methods

A carboplatin-resistant retinoblastoma cell line (Y79R) was established in vitro. RNA-seq and microRNA-seq were constructed between Y79 and Y79R cells. RNA interference, RT-PCR, Western blot (WB), and flow cytometry were used to verify the expression of genes and proteins between the two cell lines. The TargetScan database was used to predict the microRNAs that regulate the target genes. STING sites and Co-Immunoprecipitation (COIP) were used to study protein–protein interactions.

Results

GDNF was speculated to be the top changed gene in the drug resistance in Y79R cell lines. Moreover, the speculation was verified by subsequent RT-PCR and WB results. When the expression of GDNF was knocked down, the IC50 of the Y79R cell line significantly reduced. GDNF was found to be the target gene of miR-211-5p. Downregulation of miR-211-5p promotes carboplatin resistance in human retinoblastoma Y79 cells. MiR-211-5p can regulate the expression of GDNF. Our further research also found that GDNF can bind to LIF which is also a secreted protein.

Conclusion

Our results suggest that downregulation of miR-211-5p promotes carboplatin resistance in human retinoblastoma Y79 cells, and this process can be affected by GDNF–LIF interaction. These results can provide evidence for the reversal of drug resistance of RB.

Targeting of histone methyltransferase DOT1L plays a dual role in chemosensitization of retinoblastoma cells and enhances the efficacy of chemotherapy

Aberrant and exclusive expression of chromatin regulators in retinoblastoma (RB) in contrast to terminally differentiated normal retina presents a unique opportunity of selective targeting for RB. However, precise roles of these chromatin regulators in RB development and their potential as therapeutic targets have not been defined thoroughly. Here, we report that targeting of disruptor of telomeric silencing 1-like (DOT1L), a histone H3K79 methyltransferase, sensitizes RB cells to chemotherapeutic drugs by impairing the DNA damage response and thereby potentiating apoptosis while it is largely inefficacious as a single-agent therapy. Moreover, we identified high mobility group AT-hook 2 (HMGA2) as a novel DOT1L target gene in RB cells and found that its aberrant expression is dependent on DOT1L. As HMGA2 depletion reduced CHK1 phosphorylation during DNA damage response and augmented the drug sensitivity in RB cells, our results suggested that DOT1L targeting has a dual role in chemosensitization of RB cells by directly interfering with the immediate involvement of DOT1L in early DNA damage response upon genotoxic insults and also by downregulating the expression of HMGA2 as a rather late effect of DOT1L inhibition. Furthermore, we provide the first preclinical evidence demonstrating that combined therapy with a DOT1L inhibitor significantly improves the therapeutic efficacy of etoposide in murine orthotopic xenografts of RB by rendering the response to etoposide more potent and stable. Taken together, these results support the therapeutic benefits of DOT1L targeting in combination with other chemotherapeutic agents in RB, with mechanistic insights into how DOT1L targeting can improve the current chemotherapy in an RB cell-selective manner.

High-Risk Histopathologic Features of Retinoblastoma Treated at a Tertiary Hospital in West Java, Indonesia

Purpose

To evaluate the histopathological characteristics of clinically advanced retinoblastoma (RB) and its relationship with tumor differentiation.

Methods

This was a cross-sectional study of primary enucleated group D/E intraocular RB using medical records from 2017 to 2020 in a tertiary referral hospital. Cases with incomplete histopathological results were excluded. Tumors were classified into well, moderately, and poorly differentiated and undifferentiated. High-risk histopathological features were classified as per Thaung and Karaa [Community Eye Health. 2018;31(101):17-3].

Results

This study included 121 patients (129 eyes), of which 32.2% were diagnosed at 25-36 months. High-risk features (HRFs) were found in 100/129 eyes, and of 73 complete histopathological results, the 2 most common HRFs were postlaminar optic nerve invasion and massive choroidal invasion. RB was poorly differentiated in 69.9% and well differentiated in 12.3% of eyes. There was no statistically significant association between any HRFs and tumor differentiation, with age >2 years associated with tumor differentiation (p < 0.05).

Conclusion

The frequency of HRFs is 77.5% of primary enucleated eyes, mainly poorly and undifferentiated cells, particularly in children aged >2 years old.

Carboplatin- and Etoposide-Loaded Lactoferrin Protein Nanoparticles for Targeting Cancer Stem Cells in Retinoblastoma In Vitro

Purpose

Cancer stem cells (CSCs) are known to contribute to tumor relapses by virtue of their chemoresistance. With the knowledge that nanoformulations can overcome drug resistance, we evaluated the efficacy and cytotoxicity of clinical-grade carboplatin (CPT)– and etoposide (ETP)–loaded lactoferrin nanoparticles (Lf-Nps) on total, CD133-enriched (non-CSC), and CD133-depleted (CSC) populations of retinoblastoma (Rb) Y79 cells.

Methods

Physicochemical properties of drug-loaded Lf-Nps were measured with transmission electron microscopy and attenuated total reflectance–Fourier transform infrared. The encapsulation efficiency, uptake, and release of drug-loaded Lf-Nps were measured using high-performance liquid chromatography and a UV-visible spectrophotometer. Cytotoxicity of the standard and drug-loaded Lf-Nps was evaluated by the MTT assay.

Results

The mean (SD) size and encapsulation efficiency of Lf-CPT and Lf-ETP were 61.2 (3.94) nm, 60% and 45.15 (5.85) nm, 38%, respectively, and the drug release efficiency was highest at pH 6. The increased drug uptake and lower release of drug-loaded Lf-Nps were observed in CSC and non-CSC populations compared to their standard forms. The relative increase of drug uptake and sustained intracellular retention of the drug-loaded Lf-Nps compared to standard drugs showed an enhanced cytotoxicity up to 50%, especially in Rb Y79 CSCs (IC₅₀: CPT, 230.3; Lf-CPT, 118.2; ETP, 198.1; and Lf-ETP, 129) compared to non-CSCs.

Conclusions

Our study documents an increase in drug uptake, retention, and cytotoxicity of Lf-CPT and Lf-ETP on Y79 CSCs and non-CSCs as compared to their standard drugs in vitro. The reversal of chemoresistance in the CSC population by nanoformulation appears promising with the potential to pave the way for improved targeted therapy and better clinical outcomes.

miR-130a-3p Enhances the Chemosensitivity of Y79 Retinoblastoma Cells to Vincristine by Targeting PAX6 Expression

PURPOSE

Chemoresistance remains the primary obstacle threatening the prognosis of retinoblastoma (RB). microRNAs (miRNAs) are acknowledged as critical regulators of drug resistance. This study explored the molecular mechanism of miR-130a-3p affecting the chemosensitivity of RB to vincristine (VCR).

METHODS

miR-130a-3p expression of human retinal astrocytes and RB cell lines (Y79, WERI-Rb-1, SO-Rb50, and SO-Rb70) was detected using RT-qPCR. VCR-resistant RB cell line Y79/VCR was induced. miR-130a-3p expression of Y79/VCR cell line and its corresponding parental cell line was detected. Y79/VCR cells were subjected to miR-130a-3p overexpression treatment. The cell proliferation was measured using MTT assay, and the IC50 value and drug resistance index were examined using CCK-8 assay. The targeting relationship between miR-130a-3p and PAX6 was predicted through bioinformatics analysis and verified using dual-luciferase assay. Functional rescue experiments were conducted to confirm the role of PAX6 in chemosensitivity of RB cells. The effect of miR-130a-3p on tumorigenesis and VCR sensitivity was observed in vivo.

RESULTS

miR-130a-3p was downregulated in VCR-resistant RB cells. Overexpression of miR-130a-3p repressed the proliferation of Y79/VCR cells and enhanced chemosensitivity. miR-130a-3p targeted PAX6 expression. Overexpression of PAX6 reversed the effect of miR-130a-3p on chemosensitivity of Y79/VCR cells. Overexpression of miR-130a-3p suppressed tumor growth and reduced VCR resistance in vivo.

CONCLUSIONS

miR-130a-3p enhanced the chemosensitivity of Y79 RB cells to VCR by targeting PAX6 expression.

Case Report: Phototherapeutic Keratectomy for Band Keratopathy Secondary to Chemo-Laser-Cryotherapy for Retinoblastoma

Purpose: To report the clinical outcomes of phototherapeutic keratectomy (PTK) for pediatric band keratopathy after treatment for retinoblastoma.

Methods: A 5-year-old boy presented with a 2-year history of poor visual acuity and a horizontal gray-white band across the central cornea in the right eye. He was diagnosed with band keratopathy after chemo-laser-cryotherapy for retinoblastoma. The band keratopathy was treated via PTK using the Mel-90 excimer laser with an optical treatment zone of 7.0 mm and ablation depth of 120 μm. The patient was followed at 1 week and 3 months postoperatively.

Results: Surgery and postoperative follow-up were uneventful. At the 3-month follow-up, the uncorrected distant visual acuity of the right eye improved to 20/125, and the corrected distance visual acuity improved to 20/70 with a refraction of +10.00 D/−2.50 DC × 15. The clarity of the ablated area was evidently improved. The central corneal thickness decreases from 612 to 584 μm. The optical coherence tomography showed the thin band of hyperreflectivity in the ablated area disappeared, corneal transparency improved and the corneal surface smoothened.

Conclusions: PTK is a safe and effective procedure to treat band keratopathy following treatment of retinoblastoma in children. Early intervention can reduce the risk of developing deprivation amblyopia.

Stem-Cell Therapy Following High-Dose Chemotherapy in Advanced Retinoblastoma: A Systematic Review

PURPOSE

To analyze the risk and benefit of high-dose chemotherapy followed by stem cell transplantation (HDCT-SCT) treatment in patients with advanced retinoblastoma.

DESIGN

Systematic review.

METHODS

A comprehensive literature search from 4 online databases, including PubMed, Scopus, EBSCO, and Cochrane was done for original studies evaluating the use of HDCT followed by SCT in the treatment of patients with advanced retinoblastoma. The last search was performed on April 15, 2020.

RESULTS

A total of 35 studies consisting of 160 patients were considered suitable for inclusion. After HDCT-SCT treatment, 108/160 (67.5%) patients were alive with no evidence of disease at the last follow-up. The incidence of secondary malignancy in our data was also relatively low, which was 16/160 (10%) patients. The side effects were mainly hematological and gastrointestinal toxicities. The prognosis for metastatic cases especially the one to the central nervous system (CNS) remains poor, as shown in our data that 22 of 44 (50%) patients died due to the evidence of disease, and 12 of 44 (27%) patients acquired CNS relapse and died.

CONCLUSIONS

HDCT-SCT is a promising treatment option in patients with advanced retinoblastoma. The use of HDCT-SCT in CNS metastases needs to be carefully considered, possibly by adding thiotepa or topotecan to improve tumor control. Further randomized clinical trials are needed to draw firm conclusion regarding its safety and efficacy.

Reasons for missed chemotherapy appointments in retinoblastoma patients undergoing chemotherapy: A report from a Tertiary Care Hospital from India

Background

Delays in chemotherapy due to missed‐appointments can lead to sub‐optimal outcomes in any cancer. Missed appointments or delayed follow up are an important concern in the treatment of pediatric cancers as it compromises the patient's health and overall outcomes.

Aim

This study was conducted to understand the reasons responsible for missed‐appointments in Retinoblastoma (RB) patients scheduled for daycare based chemotherapy.

Methods

We prospectively recorded the causes for missed‐appointments in RB patients from February 2018 to September 2018. A delay of more than 48‐hours from the pre‐scheduled date of chemotherapy was categorized as a “missed‐appointment.”

Results

Out of 870 scheduled visits of patients with RB for chemotherapy to our center, there were 122 (14%) instances of missed‐appointments during the study period. There were 40 instances (4.6%) where the patient had missed‐appointments (possibly avoidable reasons). These 40 instances occurred in 33 patients who had a median age of 29 months (IQR 22.5‐51.5 m) with 22 males. Six patients lived within 100 km of the treating center, 12 lived between 100 and 500 km, and 15 patients lived beyond 500 km. The median length of delay was 13.75 days (IQR‐7‐20.75 days). Twenty‐seven patients used a train as a means of transport, and 10 used the state‐bus. The main cause of delay was the illness of other family members (52.5%) followed by financial issues (27.5%), transport‐related problems (10%), and absence of an adult to accompany (10%).

Conclusion

Causes for missed‐appointments for chemotherapy in RB patients were multifactorial and included the illness of other family members, financial issues, distance/transport‐related problems, and no caregiver to accompany. The future study with a large sample size with a multicenter design is needed to confirm the results of the current study and to know the deficiency in the improvement of the follow‐up RB patients.

Modern treatment of retinoblastoma: A 2020 review

Retinoblastoma management remains complex, requiring individualized treatment based on International Classification of Retinoblastoma (ICRB) staging, germline mutation status, family psychosocial factors and cultural beliefs, and available institutional resources. For this 2020 retinoblastoma review, PubMed was searched for articles dated as early as 1931, with an emphasis on articles from 1990 to the present day, using keywords of retinoblastoma, chemotherapy, intravenous chemotherapy, chemoreduction, intra-arterial chemotherapy, ophthalmic artery chemosurgery, intravitreal chemotherapy, intracameral chemotherapy, cryotherapy, transpupillary thermotherapy, laser, radiation, external beam radiotherapy, plaque radiotherapy, brachytherapy, and enucleation. We discuss current treatment modalities as used in the year 2020, including intravenous chemotherapy (IVC), intra-arterial chemotherapy (IAC), intravitreal chemotherapy (IvitC), intracameral chemotherapy (IcamC), consolidation therapies (cryotherapy and transpupillary thermotherapy [TTT]), radiation-based therapies (external beam radiotherapy [EBRT] and plaque radiotherapy), and enucleation. Additionally, we present a consensus treatment algorithm based on the agreement of three North American retinoblastoma treatment centers, and encourage further collaboration amongst the world's most expert retinoblastoma treatment centers in order to develop consensus management plans and continue advancement in the identification and treatment of this childhood cancer.

Chromatin regulators in retinoblastoma: Biological roles and therapeutic applications

Retinoblastoma (RB) is a pediatric ocular tumor mostly occurring due to the biallelic loss of RB1 gene in the developing retina. Early studies of genomic aberrations in RB have provided a valuable insight into how RB can progress following the tumor-initiating RB1 mutations and have established a notion that inactivation of RB1 gene is critical to initiate RB but this causative genetic lesion alone is not sufficient for malignant progression. With the advent of high-throughput sequencing technologies, we now have access to the comprehensive genomic and epigenetic landscape of RB and have come to appreciate that RB tumorigenesis requires both genetic and epigenetic alterations that might be directly or indirectly driven by RB1 loss. This integrative perspective on RB tumorigenesis has inspired research efforts to better understand the types and functions of epigenetic mechanisms contributing to RB development, leading to the identification of multiple epigenetic regulators misregulated in RB in recent years. A complete understanding of the intricate network of genetic and epigenetic factors in modulation of gene expression during RB tumorigenesis remains a major challenge but would be crucial to translate these findings into therapeutic interventions. In this review, we will provide an overview of chromatin regulators identified to be misregulated in human RB among the numerous epigenetic factors implicated in RB development. For a subset of these chromatin regulators, recent findings on their functions in RB development and potential therapeutic applications are discussed.

Comparison of the therapeutic effects of lobaplatin and carboplatin on retinoblastoma in vitro and in vivo

Retinoblastoma (RB) is one of the most aggressive malignancies affecting infants and children. Platinum drugs are commonly used in the treatment of RB; however, their efficacy is often compromised by drug resistance and severe toxicity. The present study aimed to investigate and compare the toxicity and antitumor activity of the third-generation platinum drugs, carboplatin and lobaplatin, in vitro and in vivo. The Y79 RB cell line was treated with carboplatin or lobaplatin in vitro and then used to establish xenografts in immunodeficient nude mice in vivo; the effects of pharmacological doses of these drugs were then assessed. High concentrations of carboplatin and lobaplatin markedly inhibited Y79 RB cell proliferation in vitro. In addition, the lobaplatin group exhibited higher proportions of early-stage apoptotic cells than the carboplatin group, while no significant differences in the proportions of cells in the S phase were observed between the 2 groups, as shown by flow cytometry. Significant changes in the E2F1/Cdc25a/Cdk2 pathway in the RB cells were detected by RNA-seq following carboplatin or lobaplatin intervention. RT-qPCR, immunofluorescence and immunohistochemical analyses in vivo and in vitro demonstrated that the trends of drug-induced inhibition of tumor pathological changes may have been regulated through the E2F1/Cdc25a/Cdk2 pathway, and that lobaplatin was more effective than carboplatin in controlling tumors in vivo. On the whole, the findings of the present study demonstrate that lobaplatin is associated with lower cytotoxicity and exerts more prominent therapeutic effects than carboplatin on Y79 RB cells in vitro and in mice in vivo.

CD24 blunts the sensitivity of retinoblastoma to vincristine by modulating autophagy

Retinoblastoma (RB) is the most common childhood malignant intraocular tumor. The clinical efficacy of vincristine (VCR) in the treatment of RB is severely limited by drug resistance. Here, we found that CD24, a GPI-anchored protein, was overexpressed in human RB tissues and RB cell lines, and was associated with the sensitivity of RB cells in response to VCR therapy. We demonstrated that CD24 plays a critical role in impairing RB sensitivity to VCR via regulating autophagy. Mechanistically, CD24 recruits PTEN to the lipid raft domain and regulates the PTEN/AKT/mTORC1 pathway to activate autophagy. Lipid raft localization was essential for CD24 recruitment function. Collectively, our findings revealed a novel role of CD24 in regulating RB sensitivity to VCR and showed that CD24 is a potential target for improving chemotherapeutic sensitivity and RB patient outcomes.

Different transcriptome profiles between human retinoblastoma Y79 cells and an etoposide-resistant subline reveal a chemoresistance mechanism

Background

Retinoblastoma (RB) is the most frequent pediatric retinal tumor. In the present study, to elucidate chemoresistance mechanisms and identify potential biomarkers in RB, we utilized RNA sequencing (RNAseq) technological platforms to reveal transcriptome profiles and identify any differentially expressed genes (DEGs) between an etoposide drug-resistant subline (Y79/EDR) and parental Y79 cells.

Methods

To test whether Y79/EDR cells showed resistance to antineoplastic agents for RB, we treated the cells with etoposide, carboplatin and vincristine and analyzed them with a Cell Counting Kit-8 (CCK-8). Y79/EDR and parental Y79 cells were used for RNAseq and bioinformatics analysis to enable a genome-wide review of DEGs between the two lines using the DESeq R package (1.10.1). Then, DEG enrichment in Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways was analyzed with KOBAS software. Next, real-time quantitative reverse transcription polymerase chain reaction (real time QRT-PCR) and cytotoxicity assays were performed to experimentally and functionally validate the identified candidate biomarkers.

Results

Y79/EDR cells showed resistance to etoposide, carboplatin and vincristine at different concentrations. In total, 524 transcripts were differentially expressed in Y79/EDR cells based on analysis of fragments per kilobase of transcript per million fragments mapped (FPKM); among these, 57 genes were downregulated and 467 genes were upregulated in Y79/EDR cells compared to parental Y79 cells. We selected candidate DEGs, including ARHGAP9, HIST1H4H, RELN, DDIT4, HK2, STC1 and PFKFB4, for mRNA expression validation with real time QRT-PCR assays and found that the expression levels determined by real time QRT-PCR were consistent with the RNAseq data. Further studies involving downregulation of ARHGAP9 with a specific siRNA showed that ARHGAP9 altered the cellular sensitivity of Y79 cells to etoposide and carboplatin.

Conclusion

Our initial findings provided a genomic view of the transcription profiles of etoposide-induced acquired resistance in RB. Follow-up studies indicated that ARHGAP9 might be a chemoresistance biomarker in RB, providing insight into potential therapeutic targets for overcoming acquired chemoresistance in RB. These findings can aid in understanding and overcoming chemoresistance during treatment of RB in the clinic.

Clinical relevance of the comparative expression of immune checkpoint markers with the clinicopathological findings in patients with primary and chemoreduced retinoblastoma

PURPOSE

The goal of this study is to identify the pathological findings and expression of immune checkpoint marker (PD-1, PD-L1, and CTLA-4) in the tumor microenvironment of both primary and chemoreduced retinoblastoma and correlate them with clinicopathological parameters and patient outcome.

METHODS

Total of 262 prospective cases was included prospectively in which 144 cases underwent primary enucleation and 118 cases received chemotherapy/radiotherapy before enucleation (chemoreduced retinoblastoma). Immunohistochemistry, qRT-PCR and western blotting were performed to evaluate the expression pattern of immune checkpoint markers in primary and chemoreduced retinoblastoma.

RESULTS

Tumor microenvironment were different for both primary and chemoreduced retinoblastoma. Expression of PD-1 was found in 29/144 (20.13%) and 48/118 (40.67%) in primary and chemoreduced retinoblastoma, respectively, whereas PD-L1 was expressed in 46/144 (31.94%) and 22/118 (18.64%) in cases of primary and chemoreduced retinoblastoma, respectively. Expression pattern of CTLA-4 protein was similar in both groups of retinoblastoma. On multivariate analysis, massive choroidal invasion, bilaterality and PD-L1 expression (p = 0.034) were found to be statistically significant factors in primary retinoblastoma, whereas PD-1 expression (p = 0.015) and foamy macrophages were significant factors in chemoreduced retinoblastoma. Overall survival was reduced in cases of PD-L1 (80.76%) expressed primary retinoblastoma, and PD-1 (63.28%) expressed chemoreduced retinoblastoma.

CONCLUSIONS

This is the first of its kind study predicting a relevant role of the immune checkpoint markers in both groups of primary and chemoreduced retinoblastoma with prognostic significance. Differential expression of these markers in both group of retinoblastoma is a novel finding and might be an interesting and beneficial target for chemoresistant tumors.

Low retinal toxicity of intravitreal carboplatin associated with good retinal tumour control in transgenic murine retinoblastoma

BACKGROUND

Retinoblastoma is a rare intraocular malignancy in children. Current treatments have many adverse effects. New therapeutic approaches like intravitreal injections of chemotherapies are currently being developed but their toxicities need to be evaluated on animal models. This study compares the efficacy and toxicity of intravitreal melphalan, topotecan and carboplatin, alone or in combination (sequential administration), in the LHBetaTag retinoblastoma mice.

METHODS

Mice were divided into nine groups: control, carboplatin 1.5 and 4 μg, melphalan 0.1 and 1 μg, topotecan 0.1 and 1 μg, carboplatin 4 μg/topotecan 0.1 μg and melphalan 1 μg/topotecan 0.1 μg. The follow-up was performed using fundus imaging and optical coherence tomography combined with histopathological analysis. Absence of tumour and presence of calcified tumours were the criteria for therapeutic response assessment. Ocular complications were assessed after four weekly injections. Retinal toxicity was defined by the decrease of retinal thickness and of the number of retinal layers.

RESULTS

Topotecan was inactive on retinal tumours. Melphalan (1 μg) led to a complete tumour control in 91.7% of eyes. Carboplatin strongly decreased the tumour burden (85.7-93.8% of eyes without retinal tumour). The intravitreal injection itself led to ocular complications (25% of media opacities and 45.7% of retinal detachment). Only melphalan at 1 μg showed a strong retinal toxicity. The two combinations showed a good efficacy in reducing the number of eyes with retinal tumours with a reduced retinal toxicity.

CONCLUSIONS

This preclinical study suggests that intravitreal injection of carboplatin has a low toxicity and could be evaluated in clinical practice to treat patients suffering from retinoblastoma.

Drug Repurposing for Retinoblastoma: Recent Advances

Retinoblastoma is the intraocular malignancy that occurs during early childhood. The current standard of care includes chemotherapy followed by focal consolidative therapies, and enucleation. Unfortunately, these are associated with many side and late effects. New drugs and/or drug combinations need to be developed for safe and effective treatment. This compelling need stimulated efforts to explore drug repurposing for retinoblastoma. While conventional drug development is a lengthy and expensive process, drug repurposing is a faster, alternate approach, where an existing drug, not meant for treating cancer, can be repurposed to treat retinoblastoma. The present article reviews various attempts to test drugs approved for different purposes such as calcium channels blockers, non-steroidal antiinflammatory drugs, cardenolides, antidiabetic, antibiotics and antimalarial for treating retinoblastoma. It also discusses other promising candidates that could be explored for repurposing for retinoblastoma.

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.

Ginsenoside-Rg5 Inhibits Retinoblastoma Proliferation and Induces Apoptosis through Suppressing BCL2 Expression

BACKGROUND/AIMS

Although the cure rate for retinoblastoma is high, surviving patients are at risk for developing secondary cancers and require life-long follow-up. It is imperative to discover and develop novel therapeutic agents with better efficiency and fewer adverse effects. Ginsenoside-Rg5 is an active derivate from ginseng and exerts anti-cancer activity in breast cancer cells. However, it is still unclear whether ginsenoside-Rg5 has similar anti-cancer functions in retinoblastoma.

METHODS

Retinoblastoma cells were treated with ginsenoside-Rg5, followed by MTT assay analysis of the cell viability, cell number assay and colony formation assay analyses of cell proliferation, and flow cytometric analysis of apoptosis. Gene mRNA levels and protein levels were determined by quantitative real-time PCR and Western blot, respectively.

RESULTS

Ginsenoside-Rg5 inhibited retinoblastoma cell viability in a dose-dependent and time-dependent manner via preventing cell proliferation and inducing cell apoptosis. BCL2 expression was downregulated by ginsenoside-Rg5 treatment via inactivating the AKT signaling pathway. BCL2 overexpression completely eliminated the inhibitory effect of ginsenoside-Rg5 on cancer cell viability.

CONCLUSION

Ginsenoside-Rg5 inhibits cell proliferation and induces apoptosis in retinoblastoma cells by inactivating the AKT signaling pathway, thereby downregulating BCL2 expression.

Clinical and genetic associations for carboplatin-related ototoxicity in children treated for retinoblastoma: A retrospective noncomparative single-institute experience

BACKGROUND

Children with retinoblastoma treated with carboplatin chemotherapy risk moderate to severe, irreversible hearing loss. Based on published evidence, we hypothesized that ototoxicity risk is associated with clinical parameters and variants in candidate genes in drug metabolism pathways (methyltransferases [thiopurine S-methyltransferase, TPMT] and [catechol-O-methyltransferase, COMT], and drug transporter ABCC3).

PROCEDURE

We retrospectively reviewed clinical records of patients with retinoblastoma treated with carboplatin chemotherapy regarding age (at diagnosis and chemotherapy initiation), chemotherapy sessions (cycles number, drug doses, and cumulative carboplatin dose), and hearing loss (defined as ototoxicity ≥grade 2 by at least one classification system). Blood samples were genotyped for genetic variants in TPMT (rs12201199, rs1800460), COMT (rs4646316, rs9332377), and ABCC3 (rs1051640) by quantitative PCR and confirmed by allele-specific PCR. Univariate statistical tests, receiver-operating characteristic analysis, and Kaplan-Meier curves were used to examine the association between hearing loss, clinical factors, and variants in candidate genes.

RESULTS

Audiometric data and stored DNA were available for 71 patients with retinoblastoma (88% carried an RB1 pathogenic variant allele). Median carboplatin cumulative dose was 1,400 mg/m² (260-5,148 mg/m² ). Ototoxicity occurred in 18 patients (25%), strongly associated with age at diagnosis (P = 0.01) and age at chemotherapy initiation (OR = 4.99, P = 0.008). The highest likelihood ratio of hearing loss was associated with chemotherapy initiation <4.25 months of age. Ototoxicity was not associated with any tested genetic variants.

CONCLUSIONS

We observed a 25% prevalence of ototoxicity in patients with retinoblastoma treated with carboplatin, higher than previously published. Age at chemotherapy initiation was associated with carboplatin-induced ototoxicity, with children <4.25 months of age at highest risk.

Comparison between intravenous chemotherapy and intra-arterial chemotherapy for retinoblastoma: a meta-analysis

Background

Intravenous chemotherapy (IVC) and intra-arterial chemotherapy (IAC) have become the primary treatments for retinoblastoma; however, some controversy remains over which method is more effective. We conducted a meta-analysis to compare the clinical efficacy of IVC and IAC.

Methods

We systematically searched literature published on PubMed, Embase, and Cochrane Library up to May 2017. Studies containing either IAC or IVC that reported on efficacy were included. The effects estimate was expressed as a pooled rate with 95% confidence interval (CI), using a fixed-effects or random-effects model.

Results

Twenty-six studies were identified which included 1541 eyes (IAC: 11 trials, 445 eyes; IVC: 16 trials, 1096 eyes). The mean follow-up times were 49.4 months (range, 13.0–105.3 months) for IVC and 21.7 months (range, 8.8–38.7 months) for IAC. For the International Classification of Intraocular Retinoblastoma (ICRB) grading, the overall success rate was higher with IAC than with IVC (75.7% [95%CI: 65.7%–83.6%] vs. 69.5% [95%CI: 51.9%–82.8%], P < 0.001). The globe salvage with IAC was higher than with IVC in group D eyes (79.5% [95%CI: 71.8%–85.4%] vs. 55.1% [95%CI: 45.6%–64.2%], P < 0.001), but not in groups B (95.8% [95%CI: 57.5%–99.7%] vs. 82.5% [95%CI: 58.9%–94.0%], P = 0.163), C (91.3% [95%CI: 65.9%–98.3%] vs. 89.0% [95%CI: 69.0%–96.7%], P = 0.212), and E eyes (51.2% [95%CI: 37.0%–65.2%] vs. 43.2% [95%CI: 18.3%–72.1%], P = 0.578). IAC and IVC were not significantly different regarding the recurrence and metastasis rates (15.0% vs. 15.4%, P = 0.148 and 2.7% vs. 0.6%, P = 0.194, respectively). For Reese-Ellsworth (RE) grading, IAC had a higher globe salvage in groups IV (90.9% [95%CI: 56.0%–98.7%] vs. 66.3% [95%CI: 32.4%–89.0%], P = 0.047) and V eyes (83.2% [95%CI: 72.0%–90.5%] vs. 59.9% [95%CI: 43.1%–74.6%], P = 0.003), but not in group I-III eyes (88.6% [95%CI: 58.3%–97.7%] vs. 88.1% [95%CI: 76.6%–94.4%], P = 0.244). The overall success rate was higher in IAC than in IVC (87.1% [95%CI: 78.1%–92.7%] vs. 77.3% [95%CI: 68.1%–84.4%], P = 0.033).

Conclusions

IAC may be superior to IVC for the treatment of retinoblastoma, with a higher overall success rate and higher globe salvage in group D or groups IV and V eyes.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4406-6) contains supplementary material, which is available to authorized users.

UHRF1 depletion sensitizes retinoblastoma cells to chemotherapeutic drugs via downregulation of XRCC4

UHRF1 (ubiquitin-like with PHD and ring finger domains 1) is highly expressed in various human cancers including retinoblastoma, and associated with tumor-promoting effects such as inhibition of apoptosis and high proliferation. However, the molecular mechanisms underlying tumor-promoting functions of UHRF1 in retinoblastoma still remain elusive. Here, we show that stable knockdown of UHRF1 renders retinoblastoma cells sensitized to conventional chemotherapeutic drugs such as etoposide and camptothecin, resulting in enhanced DNA damage and apoptotic cell death. We found that UHRF1-depleted retinoblastoma cells can recognize DNA damages normally but have markedly low expression of XRCC4 (X-ray repair cross complementing 4) among the components of nonhomologous end-joining (NHEJ) repair complex. Conversely, overexpression of UHRF1 increased the XRCC4 expression and stable knockdown of XRCC4 sensitized retinoblastoma cells to etoposide treatment, suggesting that XRCC4 is a key mediator for the drug sensitivity upon UHRF1 depletion in retinoblastoma cells. Consistent with the findings, chromatin association of DNA ligase IV in response to acute DNA damage was found to be significantly reduced in UHRF1-depleted retinoblastoma cells and functional complementation for XRCC4 in UHRF1-depleted cells attenuated the drug sensitivity, demonstrating that XRCC4 downregulation in UHRF1-depleted cells impaired DNA repair and consequently induced robust apoptosis upon genotoxic drug treatment. In human primary retinoblastoma, high expression of UHRF1 and XRCC4 could be detected, and elevated XRCC4 expression correlated with reduced apoptosis markers, implying that UHRF1-mediated XRCC4 upregulation under pathophysiological conditions triggered by RB1 gene inactivation may confer protection against endogenous DNA damages that arise during retinoblastoma development. Taken together, these results present a new mechanistic insight into how UHRF1 mediates its tumor-promoting functions in retinoblastoma, and also provide a basis for UHRF1 targeting to improve the efficacy of current chemotherapy for retinoblastoma treatment.

Expression of multidrug resistance proteins in retinoblastoma

AIM

To elucidate the mechanism of multidrug resistance in retinoblastoma, and to acquire more insights into in vivo drug resistance.

METHODS

Three anticancer drug resistant Y79 human RB cells were generated against vincristine, etoposide or carboplatin, which are used for conventional chemotherapy in RB. Primary cultures from enucleated eyes after chemotherapy (PCNC) were also prepared. Their chemosensitivity to chemotherapeutic agents (vincristine, etoposide and carboplatin) were measured using MTT assay. Western blot analysis was performed to evaluate the expression of p53, Bcl-2 and various multidrug resistant proteins in retinoblastoma cells.

RESULTS

Following exposure to chemotherapeutic drugs, PCNC showed less sensitivity to drugs. No significant changes observed in the p53 expression, whereas Bcl-2 expression was found to be increased in the drug resistant cells as well as in PCNC. Increased expression of P-glycoprotein (P-gp) was observed in drug resistant Y79 cells; however there was no significant change in the expression of P-gp found between primary cultures of primarily enucleated eyes and PCNC. Multidrug resistance protein 1 (Mrp-1) expression was found to be elevated in the drug resistant Y79 cells as well as in PCNC. No significant change in the expression of lung resistance associated protein (Lrp) was observed in the drug resistant Y79 cells as well as in PCNC.

CONCLUSION

Our results suggest that multidrug resistant proteins are intrinsically present in retinoblastoma which causes treatment failure in managing retinoblastoma with chemotherapy.