Retinoblastoma

Evidence in Focus: The Sparse Landscape of Randomized Trials on Retinoblastoma Treatment

Background

Retinoblastoma, although rare, is one of the most common intraocular malignancies worldwide. Its prognosis has improved significantly in the past few decades, thanks to modern treatments, like systemic, intra-arterial, and intravitreal chemotherapy. However, regarding survival, there are significant differences between high- and low-income countries, eye salvage is still a challenge worldwide, and treatment-related toxicity needs to be carefully and sufficiently managed.

Summary

To appraise the strength of supporting evidence, we performed a systematic review of randomized controlled trials investigating any therapeutic protocol for retinoblastoma. Four trials with 174 participants (188 eyes) were eligible, all pertaining to different intravenous chemotherapy regimens. Vincristine, etoposide, and carboplatin (VEC) appear superior to a 5-drug combination for stage III retinoblastoma. Moreover, etoposide and carboplatin as neoadjuvant chemotherapy followed by thermochemotherapy seem to offer better local control than vincristine and carboplatin. However, increasing carboplatin dose in the VEC protocol failed to improve treatment efficacy.

Key Messages

Retinoblastoma is a success story of modern medicine. However, only intravenous chemotherapy has been studied through randomized trials, while evidence for the most novel retinoblastoma treatments has mainly stemmed from observational studies. International collaborations for multicenter randomized trials could overcome difficulties and increase certainty and precision in the field.

miR-4529-3p Promotes the Progression of Retinoblastoma by Inhibiting RB1 Expression and Activating the ERK Signaling Pathway

Retinoblastoma (RB) is a malignant ocular cancer that affects children. Several microRNAs (miRNAs) have been implicated in RB regulation. The present study aimed to investigate the role of miR-4529-3p in RB pathogenesis. Scratch, Transwell, and Cell Counting Kit (CCK)-8 assays were conducted to assess the migratory, invasive, and proliferative abilities of RB cells. The expression levels of miR-4529-3p, RB1, and ERK pathway-related proteins were analyzed using western blotting and real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). Target relationships were verified using dual-luciferase reporter experiments. A murine RB model was developed to analyze the effects of miR-4529-3p on RB tumor growth in vivo. Our experiments revealed high levels of miR-4529-3p and low levels of RB1 in RB tissues. Functional analyses revealed that the migratory, invasive, and proliferative abilities of RB cells were repressed by miR-4529-3p inhibition. Similarly, p-ERK 1/2 protein levels were suppressed by miR-4529-3p inhibition. Furthermore, downregulation of miR-4529-3p limited tumor growth in vivo. Mechanistically, miR-4259-3p targets RB1. Interestingly, RB1 silencing abrogated the alleviative effects of miR-4529-3p downregulation in RB cells. MiR-4529-3p promotes RB progression by inhibiting RB1 and activating the ERK pathway. This evidence suggests that the miR-4529-3p/RB1 regulatory axis may be a prospective target for RB treatment in clinical settings.

LncRNA HOTAIR facilitates proliferation and represses apoptosis of retinoblastoma cells through the miR-20b-5p/RRM2/PI3K/AKT axis

Purpose

Retinoblastoma (RB) represents an adolescent eye malignancy. Long non-coding RNA (LncRNA) HOTAIR shows aberrant expression in many malignancies. This research investigated the mechanism of HOTAIR in RB.

Methods

Normal retinal cell lines (ARPE-19 and RPE-1) and RB cell lines (ORB50, Y79, HXO-RB44, and WERI-RB) were selected for detection of HOTAIR expression by qRT-PCR. sh-HOTAIR was delivered into Y79 and HXO-RB44 cells. Cell-cycle distribution, proliferation, and apoptosis were detected by CCK-8 assay and flow cytometry. Binding relationships among HOTAIR, miR-20b-5p, and RRM2 were confirmed using dual-luciferase assay. Roles of miR-20b-5p and RRM2 in RB cell-cycle distribution, proliferation, and apoptosis were ascertained by functional rescue experiments. Murine model of xenograft tumor was established, followed by detection of tumor growth and counting of Ki67-positive cells. Expressions of proliferation- and apoptosis-associated proteins and PI3K/AKT pathway-related proteins were determined by Western blot.

Results

HOTAIR was elevated in RB cells relative to that in normal retinal cells and showed relatively high expression in Y79 and HXO-RB44 cells. sh-HOTAIR induced RB cell-cycle arrest, restrained proliferation, and strengthened apoptosis. HOTAIR functioned as the ceRNA of miR-20b-5p and targeted RRM2. RB cells had poorly-expressed miR-20b-5p and highly-expressed RRM2. miR-20b-5p downregulation or RRM2 overexpression facilitated RB cell-cycle and proliferation, suppressed apoptosis, and reversed the protective effect of sh-HOTAIR on RB. sh-HOTAIR reduced tumor growth and Ki67-positive cells in vivo and inactivated PI3K/AKT pathway.

Conclusion

LncRNA HOTAIR upregulated RRM2 by competitively binding to miR-20b-5p and activated PI3K/AKT pathway, thereby facilitating proliferation and repressing apoptosis of RB cells.

Poly ADP Ribose Polymerase Inhibitor Olaparib Targeting Microhomology End Joining in Retinoblastoma Protein Defective Cancer: Analysis of the Retinoblastoma Cell-Killing Effects by Olaparib after Inducing Double-Strand Breaks

Retinoblastoma is the most common intraocular cancer in childhood. Loss of function in both copies of the RB1 gene is the causal mutation of retinoblastoma. Current treatment for retinoblastoma includes the use of chemotherapeutic agents, such as the DNA damaging agent etoposide, which is a topoisomerase II poison that mainly generates DNA double-strand breaks (DSBs) and genome instability. Unfaithful repairing of DSBs could lead to secondary cancers and serious side effects. Previously, we found that RB knocked-down mammalian cells depend on a highly mutagenic pathway, the micro-homology mediated end joining (MMEJ) pathway, to repair DSBs. Poly ADP ribose polymerase 1 (PARP1) is a major protein in promoting the MMEJ pathway. In this study, we explored the effects of olaparib, a PARP inhibitor, in killing retinoblastoma cells. Retinoblastoma cell line Y79 and primary retinoblastoma cells expressed the cone-rod homeobox protein (CRX), a photoreceptor-specific marker. No detectable RB expression was found in these cells. The co-treatment of olaparib and etoposide led to enhanced cell death in both the Y79 cells and the primary retinoblastoma cells. Our results demonstrated the killing effects in retinoblastoma cells by PARP inhibitor olaparib after inducing DNA double-strand breaks. The use of olaparib in combination with etoposide could improve the cell-killing effects. Thus, lower dosages of etoposide can be used to treat retinoblastoma, which would potentially lead to a lower level of DSBs and a relatively more stable genome.

Retinoblastoma cell-derived exosomes promote angiogenesis of human vesicle endothelial cells through microRNA-92a-3p

Exosomes derived from tumor cells play a key role in tumor development. In the present study, we identified the bioactivity of exosomes released from WERI-Rb1 retinoblastoma cells in tumor angiogenesis, as well as the underlying mechanism, through biochemical methods and animal experiments. Our in vitro data showed that exosomes could be engulfed by human vesicle endothelial cells (HUVECs), significantly promote cell viability and induce an inflammatory response in HUVECs by increasing the expression of a series of related genes, such as IL-1, IL-6, IL-8, MCP-1, VCAM1, and ICAM1. Significant increases in migration and tube formation were also observed in the HUVECs incubated with exosomes. Moreover, experiments with a nude mouse xenotransplantation model showed that exosomes injected near tumors could be strongly absorbed by tumor cells. The numbers of endothelial cells and blood vessels were significantly increased in tumor tissues treated with exosomes compared to control tissues. Furthermore, to reveal the mechanism underlying exosome-mediated angiogenesis in retinoblastoma, we analyzed the levels of 12 microRNAs in the exosomes. Specifically, our data showed that miR-92a-3p was enriched in RB exosomes. Accordingly, miR-92a-3p was increased in the HUVECs incubated with these exosomes. After treatment with a miR-92a-3p inhibitor, the promoting effect of exosomes on the migration and tube formation of HUVECs was significantly abrogated. The expression of the angiogenesis-related genes mentioned above was markedly decreased in HUVECs. Similarly, treatment with a microRNA mimic also demonstrated that miR-92a-3p was involved in the angiogenesis of HUVECs. More importantly, bioinformatics analysis predicted that Krüppel-like factor 2 (KLF2), a member of the KLF family of zinc-finger transcription factors, might be an active target of miR-92a-3p. Notably, this prediction was confirmed both in vitro and in vivo. Thus, our work suggests that exosomal miR-92a-3p is involved in tumor angiogenesis and might be a promising therapeutic candidate for retinoblastoma.

Osteosarcoma in One of Identical Twins: Three Cases Report and a Literature Review

Background

Osteosarcoma (OS) is the most common primary malignant bone tumor occurring mainly in children and young adults. OS is usually seen in sporadic cases, and it is an extremely rare phenomenon in blood relatives, particularly among identical twins.

Case Presentation

The present study reports three cases of OS occurring in only one of identical twins. The first case is a high‐grade OS in the left proximal tibia of a 16‐year‐old girl, treated with neo‐adjuvant chemotherapy, en bloc resection, and reconstruction with a modular knee tumor prosthesis. The second one is a high‐grade OS of the left proximal tibia of a 6‐year‐old girl. The patient was treated with neo‐adjuvant chemotherapy, en bloc resection, and reconstruction with inactived autograft. The third one is a conventional OS of the right proximal tibia of a 20‐year‐old woman. She was treated with neo‐adjuvant chemotherapy, en bloc resection, and reconstruction with a custom‐made prosthesis.

Conclusions

The occurrence of OS in one of identical twins is a relatively rare event but may present the best opportunity to understand the genetic mechanisms underlying the tumorigenesis and progression of this disease in humans. A longer follow‐up period and regular imaging evaluation are needed to confirm whether the identical twin of these patients will suffer OS in the future.

Knockdown of lncRNA HOTTIP Inhibits Retinoblastoma Progression by Modulating the miR-101-3p/STC1 Axis

Objective:

Retinoblastoma (RB) is a frequent eye cancer in children. Long non-coding RNA (LncRNA) HOXA transcript at the distal tip (HOTTIP) is aberrantly expressed in cancer tissues. This study explores the underlying mechanism of lncRNA HOTTIP in RB.

Methods:

HOTTIP expression in normal retinal cells and RB cell lines was detected using qRT-PCR. The proliferation of RB cells was measured using CCK-8 and EdU assays, and apoptosis was detected using flow cytometry and Western blotting after the transfection of si-HOTTIP into Y79 cells and pc-HOTTIP into HXO-RB-44 cells. The target relationships between HOTTIP and miR-101-3p, and miR-101-3p and STC1 were predicted by bioinformatics website and verified using dual-luciferase reporter gene assay. The binding of HOTTIP and miR-101-3p was verified using RNA pull-down assay. STC1 mRNA and protein in RB cells were measured using qRT-PCR and Western blotting. Moreover, si-HOTTIP and in-miR-101-3p/in-NC, and si-HOTTIP and pc-STC1/pcDNA were co-transfected into Y79 cells respectively to evaluate cell proliferation and apoptosis. Xenograft study was conducted, and Ki67-positive expression was detected using immunohistochemical staining.

Results:

HOTTIP expression was promoted in RB tissues and cells. Downregulation of HOTTIP inhibited proliferation and promoted apoptosis of Y79 cells, while upregulation of HOTTIP promoted proliferation and inhibited apoptosis of HXO-RB-44 cells. There were target relationships between HOTTIP and miR-101-3p, and miR-101-3p and STC1. Inhibition of miR-101-3p or overexpression of STC1 reversed the effect of si-HOTTIP on the proliferation and apoptosis of RB cells. Xenograft study showed that knockdown of HOTTIP suppressed the growth of RB in vitro.

Conclusion:

It could be concluded that HOTTIP sponged miR-101-3p to upregulate STC1 expression, thereby promoting RB cell proliferation and inhibiting apoptosis.

Implementation of computational approaches to explore the deleterious effects of non-synonymous SNPs on pRB protein

Retinoblastoma 1 (RB1) is the first discovered tumor suppressor gene and recognized as the simple model system whose encoded defective protein can cause a pediatric cancer retinoblastoma. It functions as a negative regulator of the cell cycle through the interactions with members of the E2F transcription factors family. The protein of the RB1 gene (pRB) is engaged in various cell cycle processes including apoptosis, cell cycle arrest and chromatin remodeling. Recent studies on Retinoblastoma also exhibited multiple sets of point mutation in the associated protein due to its large polymorphic information in the local database. In this study, we identified the list of disease associated non-synonymous single nucleotide polymorphisms (nsSNPs) in RB1 by incorporating different computational algorithms, web servers, modeling of the mutants and finally superimposing it. Out of 826 nsSNPs, W516G and W563G were predicted to be highly deleterious variants in the conserved regions and found to have an impact on protein structure and protein-protein interaction. Moreover, our study concludes the effect of W516G variant was more detrimental in destabilizing protein's nature as compared to W563G variant. We also found defective binding of pRB having W516G mutation with E2F2 protein. Findings of this study will aid in shortening of the expensive experimental cost of identifying disease associated SNPs in retinoblastoma for which specialized personalized treatment or therapy can be formulated.Communicated by Ramaswamy H. Sarma.

Frequency of Pathogenic Germline Variants in Cancer-Susceptibility Genes in Patients With Osteosarcoma

Importance

Osteosarcoma, the most common malignant bone tumor in children and adolescents, occurs in a high number of cancer predisposition syndromes that are defined by highly penetrant germline mutations. The germline genetic susceptibility to osteosarcoma outside of familial cancer syndromes remains unclear.

Objective

To investigate the germline genetic architecture of 1244 patients with osteosarcoma.

Design, Setting, and Participants

Whole-exome sequencing (n = 1104) or targeted sequencing (n = 140) of the DNA of 1244 patients with osteosarcoma from 10 participating international centers or studies was conducted from April 21, 2014, to September 1, 2017. The results were compared with the DNA of 1062 individuals without cancer assembled internally from 4 participating studies who underwent comparable whole-exome sequencing and 27 173 individuals of non-Finnish European ancestry who were identified through the Exome Aggregation Consortium (ExAC) database. In the analysis, 238 high-interest cancer-susceptibility genes were assessed followed by testing of the mutational burden across 736 additional candidate genes. Principal component analyses were used to identify 732 European patients with osteosarcoma and 994 European individuals without cancer, with outliers removed for patient-control group comparisons. Patients were subsequently compared with individuals in the ExAC group. All data were analyzed from June 1, 2017, to July 1, 2019.

Main Outcomes and Measures

The frequency of rare pathogenic or likely pathogenic genetic variants.

Results

Among 1244 patients with osteosarcoma (mean [SD] age at diagnosis, 16 [8.9] years [range, 2-80 years]; 684 patients [55.0%] were male), an analysis restricted to individuals with European ancestry indicated a significantly higher pathogenic or likely pathogenic variant burden in 238 high-interest cancer-susceptibility genes among patients with osteosarcoma compared with the control group (732 vs 994, respectively; P = 1.3 × 10-18). A pathogenic or likely pathogenic cancer-susceptibility gene variant was identified in 281 of 1004 patients with osteosarcoma (28.0%), of which nearly three-quarters had a variant that mapped to an autosomal-dominant gene or a known osteosarcoma-associated cancer predisposition syndrome gene. The frequency of a pathogenic or likely pathogenic cancer-susceptibility gene variant was 128 of 1062 individuals (12.1%) in the control group and 2527 of 27 173 individuals (9.3%) in the ExAC group. A higher than expected frequency of pathogenic or likely pathogenic variants was observed in genes not previously linked to osteosarcoma (eg, CDKN2A, MEN1, VHL, POT1, APC, MSH2, and ATRX) and in the Li-Fraumeni syndrome-associated gene, TP53.

Conclusions and Relevance

In this study, approximately one-fourth of patients with osteosarcoma unselected for family history had a highly penetrant germline mutation requiring additional follow-up analysis and possible genetic counseling with cascade testing.

Effect of miR-515-5p on Proliferation and Drug Sensitivity of Retinoblastoma Cells

Background

Retinoblastoma (RB) is a common malignancy in children eyes. Aberrant microRNA (miR) expression is observed in many cancer cases. miR-515-5p is reported to be concerned with the course of many cancers. This study explores the role of miR-515-5p in proliferation and drug sensitivity of RB cells.

Methods

Human RB cell lines (WERI-RB1, SO-RB50 and Y79) and human retinal pigment epithelial cell line ARPE-19 were utilized in this study. Drug-resistant cells SO-RB50/VCR and SO-RB50/CBP were constructed for the following experiments. The expressions of miR-515-5p and Notch1 in RB cells were detected. Notch1 was significantly upregulated in RB cells while miR-515-5p was notably downregulated. Then, the binding relationship between miR-515-5p and Notch1 was predicted and verified.

Results

miR-515-5p negatively regulated Notch1 expression. In vitro and in vivo experiments revealed that overexpressed miR-515-5p inhibited RB cell proliferation and enhanced drug sensitivity. Functional rescue experiment suggested that miR-515-5p regulated RB cell proliferation and drug sensitivity via inhibiting Notch1 expression.

Conclusion

It could be concluded that overexpressed miR-515-5p suppressed proliferation and drug resistance of RB cells by targeting Notch1 expression, indicating that miR-515-5p might constitute a promising therapy target for RB.

Identification of driver genes with aberrantly alternative splicing events in pediatric patients with retinoblastoma

Retinoblastoma (RB) is one of the most common cancer in children. However, the specific mechanism about RB tumorigenesis has not been fully understood. In this study, to comprehensively characterize the splicing alterations in the tumorigenesis of RB, we analyzed the differential alternative splicing events in RB. Specifically, the isoforms of RB1 were downregulated in the RB samples, and a large proportion of differentially expressed genes had multiple differentially expressed transcripts (64%). We identified 1453 genes with differential alternative splicing, among which, SE accounted for the majority, followed by MXE, RI, A3SS, and A5SS. Furthermore, the biological function related to the normal function of eyes, and E2F family TFs were significantly enriched by the genes with differential alternative splicing. Among the genes associated with visual sense, ABCA4 was found to have two mutually exclusive exons, resulting in two isoforms with different functionalities. Notably, DAZAP1 was identified as one of the critical splicing factors in RB, which was potentially involved in E2F and RB pathways. Functionally, differential binding sites in DAZAP1 protein were significantly observed between RB and normal samples. Based on the comprehensive analysis of the differential alternative splicing events and splicing factors, we identified some driver genes with differential alternative splicing and critical splicing factors involved in RB, which would greatly improve our understanding of the alternative splicing process in the tumorigenesis of RB.

Next generation sequencing of RB1gene for the molecular diagnosis of ethnic minority with retinoblastoma in Yunnan

Background

Retinoblastoma is a rare intraocular malignancy and typically initiated by inactivating biallelic mutations of RB1 gene. Each year, ~ 8000 children worldwide are diagnosed for retinoblastoma. In high-income countries, patient survival is over 95% while low-income countries is ~ 30%.If disease is diagnosed early and treated in centers specializing in retinoblastoma, the survival might exceed 95% and many eyes could be safely treated and support a lifetime of good vision. In China, approximate 1100 newly diagnosed cases are expected annually and 28 hospitals covering 25 provinces established centers classified by expertise and resources for better treatment options and follow-up. Comparing with other province of eastern China, Yunnan province is remote geographically. This might result that healthcare staff have low awareness of the role of genetic testing in management and screening in families.

Methods

The patients with retinoblastoma were selected in Yunnan. DNA from blood was used for targeted gene sequencing. Then, an in-house bioinformatics pipeline was done to detect both single nucleotide variants and small insertions/deletions. The pathogenic mutations were identified and further confirmed by conventional methods and cosegregation in families.

Results

Using our approach, targeted next generation sequencing was used to detect the mutation of these 12 probands. Bioinformatic predictions showed that nine mutations were found in our study and four were novel pathogenic variants in these nine mutations.

Conclusions

It’s the first report to describe RB1 mutations in Yunnan children with retinoblastoma. This study would improve role of genetic testing for management and family screening.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12881-020-01150-7.

[Tumors and Pseudotumors of the Retina and the Ciliary Epithelium]

The variety of retinal tumors ranges from harmless lesions to benign, locally destructive tumors and life-threatening diseases, and they are not always easy to distinguish from each other. The differential diagnosis includes real neoplasia, reactive inflammatory pathologies and vascular anomalies of the fundus as well. If possible, the diagnosis should be made clinically in order to avoid the danger of tumor cell spread via invasive diagnostic tools. Nevertheless, genetic analysis of the pathology is gaining more importance and adds to the precise characterization of the diagnosis. Depending on the tumor entity, therapy in a specialized center is necessary.

Tumoren und Pseudotumoren der Netzhaut und des Ziliarepithels

Die Varietät retinaler Tumoren reicht von harmlosen Läsionen über benigne, lokal destruierende Tumoren bis hin zu lebensbedrohlichen Erkrankungen. Nicht immer lassen sie sich einfach voneinander unterscheiden. Die Diagnose sollte nach Möglichkeit klinisch gestellt werden wegen der Gefahr einer Tumorzellverschleppung durch invasive Diagnostik. Jedoch rückt die genetische Charakterisierung der Läsion immer mehr in den Vordergrund. Je nach Entität ist eine Therapie in einem spezialisierten Zentrum notwendig.

[Retinoblastoma]

Retinoblastomas represent 6% of all malignant tumors in children under 5 years old, which untreated lead to blindness in the affected eye and death due to metastases. The main symptoms are leukocoria and strabismus, which if possible, always necessitate a clarification within 1 week for exclusion of a retinoblastoma. The most frequent differential diagnoses are Coats' disease and persistent fetal vasculature (PFV) as well as other intraocular tumors, in particular astrocytomas. Systemic chemotherapy, if necessary in combination with laser hyperthermia, local chemotherapy and brachytherapy are the most important methods for eye-preserving treatment. Advanced cases mostly necessitate enucleation.

Circular RNA (circ-0075804) promotes the proliferation of retinoblastoma via combining heterogeneous nuclear ribonucleoprotein K (HNRNPK) to improve the stability of E2F transcription factor 3 E2F3

It is growingly recognized that messenger RNAs (mRNAs) are important regulators of various cancers. However, there are few reporters about the function of E2F3 in retinoblastoma (RB), which needs more exploration. In addition, the circRNA circ-0075804 was derived from the E2F3 host gene. The purpose of the study is to figure out the role and molecular regulation mechanism of E2F3 and circ-0075804 in RB. The role of E2F3 in RB was determined through E2F3 silencing and loss of expression was evaluated by real-time quantitative polymerase chain reaction (RT-qPCR), Western blot, CCK-8, colony formation, and 5-ethynyl-2'-deoxyuridine assays. The interactions between E2F3 and circ-0075804 were validated through loss and gain function of circ-0075804. Besides, the role of circ-0075804 in RB was determined by several functional assays. And the binding ability between heterogeneous nuclear ribonucleoprotein K and circ-0075804 was verified by RNA pull-down, Western blot, and RT-qPCR assays. The expression of E2F3 was upregulated in RB cell lines. Furthermore, knockdown of E2F3 inhibited cell proliferation and induced cell apoptosis in RB. And circ-0075804 positively regulated the expression of E2F3. Moreover, circ-0075804 facilitated cell proliferation and suppressed cell apoptosis. Besides, HNRNPK could bind with circ-0075804 in RB. Finally, knockdown of E2F3 partly rescued the promoting role of circ-0075804 overexpression in RB. Overall, circ-0075804 promotes the proliferation of RB via combining HNRNPK to improve the stability of E2F3, which brings new light for treating RB.

Frequency of low-level and high-level mosaicism in sporadic retinoblastoma: genotype-phenotype relationships

Somatic mutational mosaicism is a common feature of monogenic genetic disorders, particularly in diseases such as retinoblastoma, with high rates of de novo mutations. The detection and quantification of mosaicism is particularly relevant in these diseases, since it has important implications for genetic counseling, patient management, and probably also on disease onset and progression. In order to assess the rate of somatic mosaicism (high- and low-level mosaicism) in sporadic retinoblastoma patients, we analyzed a cohort of 153 patients with sporadic retinoblastoma using ultra deep next-generation sequencing. High-level mosaicism was detected in 14 out of 100 (14%) bilateral patients and in 11 out of 29 (38%) unilateral patients in whom conventional Sanger sequencing identified a pathogenic mutation in blood DNA. In addition, low-level mosaicism was detected in 3 out of 16 (19%) unilateral patients in whom conventional screening was negative in blood DNA. Our results also reveal that mosaicism was associated to delayed retinoblastoma onset particularly in unilateral patients. Finally we compared the level of mosaicism in different tissues to identify the best DNA source to identify mosaicism in retinoblastoma patients. In light of these results we recommended analyzing the mosaic status in all retinoblastoma patients using accurate techniques such as next-generation sequencing, even in those cases in which conventional Sanger sequencing identified a pathogenic mutation in blood DNA. Our results suggest that a significant proportion of those cases are truly mosaics that could have been overlooked. This information should be taking into consideration in the management and genetic counseling of retinoblastoma patients and families.

Maternal Residential Proximity to Major Roadways and Pediatric Embryonal Tumors in Offspring

The environmental determinants of pediatric embryonal tumors remain unclear. Because of the growing concern over the impact of exposures to traffic-related air pollution on pediatric cancer, we conducted a population-based study evaluating the impact of maternal residential proximity to major roadways on the risk of pediatric embryonal tumors in offspring. We identified children diagnosed with neuroblastoma, Wilms tumor, retinoblastoma, or hepatoblastoma at <5 years of age from the Texas Cancer Registry and selected unaffected controls from birth certificates. Two residential proximity measures were used: (1) distance to the nearest major roadway, and (2) within 500 m of a major roadway. Logistic regression was used to estimate the adjusted odds ratio (aOR) and 95% confidence interval (CI) for each proximity measure on pediatric embryonal tumors. The odds of an embryonal tumor were increased in children born to mothers living within 500 m of a major roadway (aOR = 1.24, 95% CI: 1.00, 1.54). This was consistent for most tumor subtypes, with the strongest associations observed for unilateral retinoblastoma (aOR = 2.57, 95% CI: 1.28, 5.15, for every kilometer closer the mother lived to the nearest major roadway). These findings contribute to the growing evidence that traffic-related air pollution may increase risk for certain pediatric tumors.

Germline and somatic genetics of osteosarcoma - connecting aetiology, biology and therapy

Clinical outcomes and treatment modalities for osteosarcoma, the most common primary cancer of bone, have changed very little over the past 30 years. The peak incidence of osteosarcoma occurs during the adolescent growth spurt, which suggests that bone growth and pubertal hormones are important in the aetiology of the disease. Tall stature, high birth weight and certain inherited cancer predisposition syndromes are well-described risk factors for osteosarcoma. Common genetic variants are also associated with osteosarcoma. The somatic genome of osteosarcoma is highly aneuploid, exhibits extensive intratumoural heterogeneity and has a higher mutation rate than most other paediatric cancers. Complex pathways related to bone growth and development and tumorigenesis are also important in osteosarcoma biology. In this Review, we discuss the contributions of germline and somatic genetics, tumour biology and animal models in improving our understanding of osteosarcoma aetiology, and their potential to identify novel therapeutic targets and thus improve the lives of patients with osteosarcoma.

Knockdown of Long Noncoding RNA (lncRNA) Metastasis-Associated Lung Adenocarcinoma Transcript 1 (MALAT1) Inhibits Proliferation, Migration, and Invasion and Promotes Apoptosis by Targeting miR-124 in Retinoblastoma

Evidence suggests that the long noncoding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is upregulated in cancer tissues, and its elevated expression is associated with hyperproliferation. However, the underlying mechanisms regarding the role of MALAT1 in retinoblastoma (RB) remain unclear. This study aimed to explore the functional role of MALAT1 in RB by targeting miR-124. The results showed that the expression of MALAT1 was significantly higher in the Y79 cell line than in the ARPE-19 cell line (p < 0.01). Moreover, MALAT1 silence inhibited cell viability, migration, and invasion and promoted apoptosis in Y79 cells (p < 0.05, p < 0.01, or p < 0.001). miR-124 was upregulated by MALAT1 silence and hence was identified as a target of MALAT1 (p < 0.05 or p < 0.001). In addition, miR-124 suppression inhibited cell apoptosis and remarkably abolished the inhibitory effects of MALAT1 silence on cell viability, migration, and invasion (p < 0.05, p < 0.01, or p < 0.001). In addition, Slug was a target of miR-124 and regulated cell viability, migration, invasion, and apoptosis in Y79 cells (p < 0.05, p < 0.01, or p < 0.001). Further, Slug silence abolished miR-124 suppression-induced inactivation of the ERK/MAPK and Wnt/β-catenin pathways. Taken together, our data highlight the pivotal role of MALAT1 in RB. Moreover, the present study elucidated the MALAT1–miR-124–ERK/MAPK and Wnt/β-catenin signaling pathways in RB, which might provide a new approach for the treatment of RB.

Childhood cancer predisposition syndromes-A concise review and recommendations by the Cancer Predisposition Working Group of the Society for Pediatric Oncology and Hematology

Heritable predisposition is an important cause of cancer in children and adolescents. Although a large number of cancer predisposition genes and their associated syndromes and malignancies have already been described, it appears likely that there are more pediatric cancer patients in whom heritable cancer predisposition syndromes have yet to be recognized. In a consensus meeting in the beginning of 2016, we convened experts in Human Genetics and Pediatric Hematology/Oncology to review the available data, to categorize the large amount of information, and to develop recommendations regarding when a cancer predisposition syndrome should be suspected in a young oncology patient. This review summarizes the current knowledge of cancer predisposition syndromes in pediatric oncology and provides essential information on clinical situations in which a childhood cancer predisposition syndrome should be suspected.

Familial retinoblastoma due to intronic LINE-1 insertion causes aberrant and noncanonical mRNA splicing of the RB1 gene

Retinoblastoma (RB, MIM 180200) is the paradigm of hereditary cancer. Individuals harboring a constitutional mutation in one allele of the RB1 gene have a high predisposition to develop RB. Here, we present the first case of familial RB caused by a de novo insertion of a full-length long interspersed element-1 (LINE-1) into intron 14 of the RB1 gene that caused a highly heterogeneous splicing pattern of RB1 mRNA. LINE-1 insertion was inferred by mRNA studies and full-length sequenced by massive parallel sequencing. Some of the aberrant mRNAs were produced by noncanonical acceptor splice sites, a new finding that up to date has not been described to occur upon LINE-1 retrotransposition. Our results clearly show that RNA-based strategies have the potential to detect disease-causing transposon insertions. It also confirms that the incorporation of new genetic approaches, such as massive parallel sequencing, contributes to characterize at the sequence level these unique and exceptional genetic alterations.

Ocular transient receptor potential channel function in health and disease

Transient receptor potential (TRP) channels sense and transduce environmental stimuli into Ca(2+) transients that in turn induce responses essential for cell function and adaptation. These non-selective channels with variable Ca(2+) selectivity are grouped into seven different subfamilies containing 28 subtypes based on differences in amino acid sequence homology. Many of these subtypes are expressed in the eye on both neuronal and non-neuronal cells where they affect a host of stress-induced regulatory responses essential for normal vision maintenance. This article reviews our current knowledge about the expression, function and regulation of TRPs in different eye tissues. We also describe how under certain conditions TRP activation can induce responses that are maladaptive to ocular function. Furthermore, the possibility of an association between TRP mutations and disease is considered. These findings contribute to evidence suggesting that drug targeting TRP channels may be of therapeutic benefit in a clinical setting. We point out issues that must be more extensively addressed before it will be possible to decide with certainty that this is a realistic endeavor. Another possible upshot of future studies is that disease process progression can be better evaluated by profiling changes in tissue specific functional TRP subtype activity as well as their gene and protein expression.

Danish retinoblastoma patients 1943-2013 - genetic testing and clinical implications

BACKGROUND

In heritable retinoblastoma there is a 50% risk of transmitting the RB1 mutation, and offspring carriers have more than 90% risk of developing retinoblastoma. Today, all newly diagnosed retinoblastoma patients in Denmark are screened for mutations in RB1, as opposed to only a minority of patients diagnosed before DNA testing was offered. Knowledge of heredity increases the chance of early diagnosis in offspring, leading to improved prognosis. We present data from the Danish retinoblastoma patients that emphasize the need for genetic counseling and RB1 screening in all untested retinoblastoma survivors.

MATERIAL AND METHODS

Data are extracted from The Danish Ocular Oncology Group Database, a national population database containing data on all Danish retinoblastoma patients since 1943.

RESULTS

In total 323 retinoblastoma patients have been diagnosed between 1943 and 2013. Since 1963, the rate has been stable around 1 per 14 000 live births with 95% of the patients surviving their retinoblastoma. Stratifying data on the time of diagnosis and status of genetic testing, the number of screened patients gradually increased from 5% in the beginning of the period to 96% in the last five-year period. A cohort of 181 retinoblastoma survivors with sporadic disease (15% heritable) did not receive genetic testing. Since the introduction of routine testing, one of 14 sporadic unilateral patients tested (7%) has been identified with a germline mutation. Before routine testing, five additional sporadic unilateral patients have been identified as heritable.

CONCLUSION

Only a minority of Danish retinoblastoma patients diagnosed before routine genetic testing was offered have been RB1 screened. To counsel the remaining untested patients and their families sufficiently regarding the risk to offspring and elevated risk of second primary cancers, we recommend information and access to genetic counseling and RB1 screening. This has ethical, psychological and possible economic consequences, and should be handled with caution.

OTX2 is a therapeutic target for retinoblastoma and may function as a common factor between C-MYC, CRX, and phosphorylated RB pathways

The homeobox transcription factor orthodenticle homeobox 2 (OTX2) plays a critical role in very early neurogenesis, but can become oncogenic when aberrantly expressed later in life. We previously discovered its novel oncogenic role in the malignant childhood brain tumor medulloblastoma and hypothesize an oncogenic role in retinoblastoma. Primary retinoblastoma tumors and cell lines were analyzed by quantitative-PCR, immunoblotting and immunohistochemistry for OTX2. The effect of modulating OTX2 expression on tumorigenesis was tested pharmacologically and by siRNA. A lentiviral shRNA-engineered vector was used for conditional knockdown studies on tumor growth in vivo. A luciferase reporter assay was used to analyze ATRA's effect on OTX2's promoter. In this study on retinoblastoma, OTX2 was frequently amplified and/or overexpressed in primary tumors and cell lines. Knockdown of OTX2 expression by siRNA or pharmacologic inhibition by all-trans retinoic acid (ATRA) repressed OTX2 expression and cell proliferation and significantly decreased tumor growth in vivo. Loss of OTX2 expression also resulted in decreased expression of C-MYC and CRX, genes previously implicated in retinoblastoma tumorigenesis. Loss of OTX2 expression increased the phosphorylation of RB, a potential mechanism of modulating cell proliferation. Aberrant expression of OTX2 may contribute to the development of retinoblastoma. OTX2 may serve as a common transcription factor that interlinks multiple tumor-driving pathways. These results also show that OTX2 can be genetically and pharmacologically targeted, providing an exciting new therapeutic option that may be less toxic and more efficacious than current treatments.

Direct involvement of retinoblastoma family proteins in DNA repair by non-homologous end-joining

Deficiencies in DNA double-strand break (DSB) repair lead to genetic instability, a recognized cause of cancer initiation and evolution. We report that the retinoblastoma tumor suppressor protein (RB1) is required for DNA DSB repair by canonical non-homologous end-joining (cNHEJ). Support of cNHEJ involves a mechanism independent of RB1's cell-cycle function and depends on its amino terminal domain with which it binds to NHEJ components XRCC5 and XRCC6. Cells with engineered loss of RB family function as well as cancer-derived cells with mutational RB1 loss show substantially reduced levels of cNHEJ. RB1 variants disabled for the interaction with XRCC5 and XRCC6, including a cancer-associated variant, are unable to support cNHEJ despite being able to confer cell-cycle control. Our data identify RB1 loss as a candidate driver of structural genomic instability and a causative factor for cancer somatic heterogeneity and evolution.

Polymodal roles of transient receptor potential channels in the control of ocular function

Maintenance of intracellular Ca²⁺ levels at orders of magnitude below those in the extracellular environment is a requisite for preserving cell viability. Membrane channels contribute to such control through modulating their time-dependent opening and closing behaviour. Such regulation requires Ca²⁺ to serve as a second messenger mediating receptor control of numerous life-sustaining responses. Transient receptor potential (TRP) channels signal transduce a wide variety of different sensory stimuli to induce responses modulating cellular function. These channels are non-selective cation channels with variable Ca²⁺ selectivity having extensive sequence homology. They constitute a superfamily made up of 28 different members that are subdivided into 7 different subfamilies based on differences in sequence homology. Some of these TRP channel isotypes are expressed in the eye and localized to both neuronal and non-neuronal cell membranes. Their activation generates intracellular Ca²⁺ transients and other downstream-linked signalling events that affect numerous responses required for visual function. As there is an association between changes in functional TRP expression in various ocular diseases, there are efforts underway to determine if these channels can be used as drug targets to reverse declines in ocular function. We review here our current knowledge about the expression, function and regulation of TRPs in different eye tissues in health and disease. Furthermore, some of the remaining hurdles are described to developing safe and efficacious TRP channel modulators for use in a clinical setting.

Hereditary lung cancer syndrome targets never smokers with germline EGFR gene T790M mutations

INTRODUCTION

Hereditary lung cancer syndromes are rare, and T790M germline mutations of the epidermal growth factor receptor (EGFR) gene predispose to the development of lung cancer. The goal of this study was to determine the clinical features and smoking status of lung cancer cases and unaffected family members with this germline mutation and to estimate its incidence and penetrance.

METHODS

We studied a family with germline T790M mutations over five generations (14 individuals) and combined our observations with data obtained from a literature search (15 individuals).

RESULTS

T790M germline mutations occurred in approximately 1% of non-small-cell lung cancer cases and in less than one in 7500 subjects without lung cancer. Both sporadic and germline T790M mutations were predominantly adenocarcinomas, favored female gender, and were occasionally multifocal. Of lung cancer tumors arising in T790M germline mutation carriers, 73% contained a second activating EGFR gene mutation. Inheritance was dominant. The odds ratio that T790M germline carriers who are smokers will develop lung cancer compared with never smoker carriers was 0.31 (p = 6.0E-05). There was an overrepresentation of never smokers with lung cancer with this mutation compared with the general lung cancer population (p = 7.4E-06).

CONCLUSION

Germline T790M mutations result in a unique hereditary lung cancer syndrome that targets never smokers, with a preliminary estimate of 31% risk for lung cancer in never smoker carriers, and this risk may be lower for heavy smokers. The resultant cancers share several features and differences with lung cancers containing sporadic EGFR mutations.

Nanomedicines in the future of pediatric therapy

Nanotechnology has become a key tool to overcome the main (bio)pharmaceutical drawbacks of drugs and to enable their passive or active targeting to specific cells and tissues. Pediatric therapies usually rely on the previous clinical experience in adults. However, there exists scientific evidence that drug pharmacokinetics and pharmacodynamics in children differ from those in adults. For example, the interaction of specific drugs with their target receptors undergoes changes over the maturation of the different organs and systems. A similar phenomenon is observed for toxicity and adverse effects. Thus, it is clear that the treatment of disease in children cannot be simplified to the direct adjustment of the dose to the body weight/surface. In this context, the implementation of innovative technologies (e.g., nanotechnology) in the pediatric population becomes extremely challenging. The present article overviews the different attempts to use nanotechnology to treat diseases in the pediatric population. Due to the relevance, though limited available literature on the matter, we initially describe from preliminary in vitro studies to preclinical and clinical trials aiming to treat pediatric infectious diseases and pediatric solid tumors by means of nanotechnology. Then, the perspectives of pediatric nanomedicine are discussed.

Intra-arterial chemotherapy for retinoblastoma. Challenges of a prospective study

PURPOSE

To report the efficacy and complications of intra-ophthalmic artery melphalan (IAM) for treatment of patients with advanced intra-ocular retinoblastoma.

METHODS

Patients with newly diagnosed, unilateral, group D retinoblastoma were included in a phase II protocol. Children with relapsed-refractory disease after systemic chemoreduction were later treated under the same guidelines.Melphalan (3–5 mg/procedure) was injected through a 1.2 F microcatheter placed into the ophthalmic artery every 21 days.

RESULTS

Eleven patients (12 eyes, eight as primary treatment) received 33 IAM procedures. The phase II protocol closed prematurely because of low accrual. The IAM technique was overall safe and could be performed successfully in 31 of 33(94%) attempts. After the second administration of IAM, very good partial response was achieved in all treated eyes. With a median follow-up time of 29.5 months (range 6–57), ocular salvage was achieved in 7 of 12 (58%) eyes. No systemic adverse events were observed. Two patients developed diffuse arteriolar sclerosis, hyperpigmentation of the retinal pigment epithelium and partial retinal atrophy after the second IAM. Both eyes were preserved with no tumour activity, good motility and perception of light, 56 and 30 months after the last IAM treatment. Multinucleated macrophages with intracytoplasmic foreign material were found in the choroid and the retina in 2 of 5 enucleated eyes.

CONCLUSION

Our study reports the activity and reproducibility of IAM in advanced retinoblastoma but also underlines the challenges of performing prospective studies on this treatment modality. Toxicity was limited to only ocular vascular events.

Enhanced sensitivity for detection of low-level germline mosaic RB1 mutations in sporadic retinoblastoma cases using deep semiconductor sequencing

Sporadic retinoblastoma (RB) is caused by de novo mutations in the RB1 gene. Often, these mutations are present as mosaic mutations that cannot be detected by Sanger sequencing. Next-generation deep sequencing allows unambiguous detection of the mosaic mutations in lymphocyte DNA. Deep sequencing of the RB1 gene on lymphocyte DNA from 20 bilateral and 70 unilateral RB cases was performed, where Sanger sequencing excluded the presence of mutations. The individual exons of the RB1 gene from each sample were amplified, pooled, ligated to barcoded adapters, and sequenced using semiconductor sequencing on an Ion Torrent Personal Genome Machine. Six low-level mosaic mutations were identified in bilateral RB and four in unilateral RB cases. The incidence of low-level mosaic mutation was estimated to be 30% and 6%, respectively, in sporadic bilateral and unilateral RB cases, previously classified as mutation negative. The frequency of point mutations detectable in lymphocyte DNA increased from 96% to 97% for bilateral RB and from 13% to 18% for unilateral RB. The use of deep sequencing technology increased the sensitivity of the detection of low-level germline mosaic mutations in the RB1 gene. This finding has significant implications for improved clinical diagnosis, genetic counseling, surveillance, and management of RB.

Human PPP1R26P1 functions as cis-repressive element in mouse Rb1

The human retinoblastoma gene (RB1) is imprinted; the mouse Rb1 gene is not. Imprinted expression of RB1 is due to differential methylation of a CpG island (CpG85), which is located in the pseudogene PPP1R26P1 in intron 2 of RB1. CpG85 serves as promoter for an alternative RB1 transcript, which is expressed from the unmethylated paternal allele only and is thought to suppress expression of the full-length RB1 transcript in cis. PPP1R26P1 contains another CpG island (CpG42), which is biallelically methylated. To determine the influence of PPP1R26P1 on RB1 expression, we generated an in vitro murine embryonic stem cell model by introducing human PPP1R26P1 into mouse Rb1. Next generation bisulfite sequencing of CpG85 and CpG42 revealed differences in their susceptibility to DNA methylation, gaining methylation at a median level of 4% and 18%, respectively. We showed binding of RNA polymerase II at and transcription from the unmethylated CpG85 in PPP1R26P1 and observed reduced expression of full-length Rb1 from the targeted allele. Our results identify human PPP1R26P1 as a cis-repressive element and support a connection between retrotransposition of PPP1R26P1 into human RB1 and the reduced expression of RB1 on the paternal allele.

Prediction and analysis of retinoblastoma related genes through gene ontology and KEGG

One of the most important and challenging problems in biomedicine is how to predict the cancer related genes. Retinoblastoma (RB) is the most common primary intraocular malignancy usually occurring in childhood. Early detection of RB could reduce the morbidity and promote the probability of disease-free survival. Therefore, it is of great importance to identify RB genes. In this study, we developed a computational method to predict RB related genes based on Dagging, with the maximum relevance minimum redundancy (mRMR) method followed by incremental feature selection (IFS). 119 RB genes were compiled from two previous RB related studies, while 5,500 non-RB genes were randomly selected from Ensemble genes. Ten datasets were constructed based on all these RB and non-RB genes. Each gene was encoded with a 13,126-dimensional vector including 12,887 Gene Ontology enrichment scores and 239 KEGG enrichment scores. Finally, an optimal feature set including 1061 GO terms and 8 KEGG pathways was obtained. Analysis showed that these features were closely related to RB. It is anticipated that the method can be applied to predict the other cancer related genes as well.

Transcriptome analyses of the human retina identify unprecedented transcript diversity and 3.5 Mb of novel transcribed sequence via significant alternative splicing and novel genes

BACKGROUND

The retina is a complex tissue comprised of multiple cell types that is affected by a diverse set of diseases that are important causes of vision loss. Characterizing the transcripts, both annotated and novel, that are expressed in a given tissue has become vital for understanding the mechanisms underlying the pathology of disease.

RESULTS

We sequenced RNA prepared from three normal human retinas and characterized the retinal transcriptome at an unprecedented level due to the increased depth of sampling provided by the RNA-seq approach. We used a non-redundant reference transcriptome from all of the empirically-determined human reference tracks to identify annotated and novel sequences expressed in the retina. We detected 79,915 novel alternative splicing events, including 29,887 novel exons, 21,757 3' and 5' alternate splice sites, and 28,271 exon skipping events. We also identified 116 potential novel genes. These data represent a significant addition to the annotated human transcriptome. For example, the novel exons detected increase the number of identified exons by 3%. Using a high-throughput RNA capture approach to validate 14,696 of these novel transcriptome features we found that 99% of the putative novel events can be reproducibly detected. Further, 15-36% of the novel splicing events maintain an open reading frame, suggesting they produce novel protein products.

CONCLUSIONS

To our knowledge, this is the first application of RNA capture to perform large-scale validation of novel transcriptome features. In total, these analyses provide extensive detail about a previously uncharacterized level of transcript diversity in the human retina.

Structural insights into the mechanism of phosphoregulation of the retinoblastoma protein

The retinoblastoma susceptibility protein RB1 is a key regulator of cell proliferation and fate. RB1 operates through nucleating the formation of multi-component protein complexes involved in the regulation of gene transcription, chromatin structure and protein stability. Phosphorylation of RB1 by cyclin-dependent kinases leads to conformational alterations and inactivates the capability of RB1 to bind partner protein. Using small angle X-ray scattering in combination with single particle analysis of transmission electron microscope images of negative-stained material we present the first three-dimensional reconstruction of non-phosphorylated RB1 revealing an extended architecture and deduce the domain arrangement within the molecule. Phosphorylation results in an overt alteration of the molecular shape and dimensions, consistent with the transition to a compact globular architecture. The work presented provides what is to our knowledge the first description of the relative domain arrangement in active RB1 and predicts the molecular movement that leads to RB1 inactivation following protein phosphorylation.

The genomic landscape of hypodiploid acute lymphoblastic leukemia

The genetic basis of hypodiploid acute lymphoblastic leukemia (ALL), a subtype of ALL characterized by aneuploidy and poor outcome, is unknown. Genomic profiling of 124 hypodiploid ALL cases, including whole-genome and exome sequencing of 40 cases, identified two subtypes that differ in the severity of aneuploidy, transcriptional profiles and submicroscopic genetic alterations. Near-haploid ALL with 24-31 chromosomes harbor alterations targeting receptor tyrosine kinase signaling and Ras signaling (71%) and the lymphoid transcription factor gene IKZF3 (encoding AIOLOS; 13%). In contrast, low-hypodiploid ALL with 32-39 chromosomes are characterized by alterations in TP53 (91.2%) that are commonly present in nontumor cells, IKZF2 (encoding HELIOS; 53%) and RB1 (41%). Both near-haploid and low-hypodiploid leukemic cells show activation of Ras-signaling and phosphoinositide 3-kinase (PI3K)-signaling pathways and are sensitive to PI3K inhibitors, indicating that these drugs should be explored as a new therapeutic strategy for this aggressive form of leukemia.

Aberrant nuclear repressor coreceptor 1 localization in human retinoblastoma

BACKGROUND/AIMS

Nuclear receptor corepressor 1 (NCoR1) is a protein complex with diverse functions in development and tumorigenesis. We investigated the pattern of expression and histopathological correlation of NCoR1 in 41 retinoblastoma tumor samples, 1 retinoblastoma cell line (WERI-Rb-1) and human retinal progenitor cells (hRPCs).

METHODS

Tissue sections from 41 retinoblastoma cases, the retinoblastoma cell line WERI-Rb-1 and hRPCs were stained with rabbit polyclonal anti-NCoR1 H76 antibody. Percentage and intensity of staining were classified by an ocular pathologist from 0 to 3. The paired t test was used to test for differences.

RESULTS

In the nonneoplastic retina, NCoR1 was expressed mainly in cell nuclei. The retinoblastoma tumor cells similarly had nuclear NCoR1 but also had a higher level of cytoplasmic NCoR1 expression compared to all 3 normal retinal cell layers (p < 0.002). In contrast to the normal retina, NCoR1 was mainly expressed in the cytoplasm of the proliferating WERI-Rb-1 cells. This cytoplasmic expression pattern was also seen in the undifferentiated hRPCs.

CONCLUSIONS

The aberrant cytoplasmic expression of NCoR1 in retinoblastoma appears to be associated with the proliferative and/or dedifferentiated properties of retinoblastoma. Further investigation into the role of NCoR1 in retinoblastoma may provide insight into how therapeutically inhibiting its nucleocytoplasmic shuttling may affect retinoblastoma tumor biology.

Integrative genomics reveals frequent somatic NF1 mutations in sporadic pheochromocytomas

Pheochromocytomas are neuroendocrine tumors of the adrenal medulla which can occur either sporadically or in the context of hereditary tumor syndromes. Whereas the genetic background of hereditary pheochromocytomas is becoming rather well-defined, very little is known about the more common sporadic form of the disease which constitutes ∼70% of all cases. In this study, we elucidate some of the molecular mechanisms behind sporadic pheochromocytoma by performing a comprehensive analysis of copy number alterations, gene expression, promoter methylation and somatic mutations in the genes RET, VHL, NF1, SDHA, SDHB, SDHC, SDHD, SDHAF2, KIF1Bβ, TMEM127 and MAX, which have been associated with hereditary pheochromocytoma or paraganglioma. Our genomic and genetic analyses of 42 sporadic pheochromocytomas reveal that a large proportion (83%) has an altered copy number in at least one of the known susceptibility genes, often in association with an altered messenger RNA (mRNA) expression. Specifically, 11 sporadic tumors (26%) displayed a loss of one allele of the NF1 gene, which significantly correlated with a reduced NF1 mRNA expression. Subsequent sequencing of NF1 mRNA, followed by confirmation in the corresponding genomic DNA (gDNA), revealed somatic truncating mutations in 10 of the 11 tumors with NF1 loss. Our results thus suggest that the NF1 gene constitutes the most frequent (24%) target of somatic mutations so far known in sporadic pheochromocytomas.

Rbf1 degron dysfunction enhances cellular DNA replication

The E2F family of transcription factors contributes to oncogenesis through activation of multiple genes involved in cellular proliferation, a process that is opposed by the Retinoblastoma tumor suppressor protein (RB). RB also increases E2F1 stability by inhibiting its proteasome-mediated degradation, but the consequences of this post-translational regulation of E2F1 remain unknown. To better understand the mechanism of E2F stabilization and its physiological relevance, we examined the streamlined Rbf1-dE2F1 network in Drosophila. During embryonic development, Rbf1 is insulated from ubiquitin-mediated turnover by the COP9 signalosome, a multi-protein complex that modulates E3 ubiquitin ligase activity. Here, we report that the COP9 signalosome also protects the Cullin4-E3 ligase that is responsible for dE2F1 proteasome-mediated destruction. This dual role of the COP9 signalosome may serve to buffer E2F levels, enhancing its turnover via Cul4 protection and its stabilization through protection of Rbf1. We further show that Rbf1-mediated stabilization of dE2F1 and repression of dE2F1 cell cycle-target genes are distinct properties. Removal of an evolutionarily conserved Rbf1 C terminal degron disabled Rbf1 repression without affecting dE2F1 stabilization. This mutant form of Rbf1 also enhanced G(1)-to-S phase progression when expressed in Rbf1-containing S2 embryonic cells, suggesting that such mutations may generate gain-of-function properties relevant to cellular transformation. Consistent with this idea, several studies have identified mutations in the homologous C terminal domains of RB and p130 in human cancer.

Therapeutic and toxicologic evaluation of anti-lipogenic agents in cancer cells compared with non-neoplastic cells

Fatty acid synthase (FASN), a multi-enzyme complex, is involved in lipid biosynthesis. FASN is over-expressed in different types of cancers and is being widely investigated for its role in cancer progression, diagnosis and therapy. Here, three inhibitors targeting different domains of FASN--cerulenin, triclosan and orlistat--were evaluated for their anti-proliferative efficacy in ocular cancer, retinoblastoma (RB) cells and their toxicity (if any) in normal cells. FASN inhibitors were tested in cultured retinoblastoma Y79 cells, normal fibroblast (3T3) and Müller glial (MIOM1) cells. Cell viability was determined by MTT-based assay, and IC(50) (50% inhibitory concentration) of the FASN inhibitors was calculated in neoplastic and non-neoplastic cells. The IC(50) after 48 and 96 hr of incubation with the three anti-FASN agents showed that cerulenin, triclosan and orlistat inhibited retinoblastoma cell proliferation in a dose- and time-dependent manner. The cancer cells exhibited differential dose- and time-dependent response/sensitivities to cerulenin, triclosan and orlistat. The 48-hr neoplastic IC(50) dosages were, however, not toxic to the normal cells. These findings were confirmed by phase-contrast microscopic assessment of cell morphology. Therapeutic index (TI) was calculated as a ratio of the IC(50) normal cells, to the IC(50) neoplastic cells. Relative to normal MIOM1 cells, TI was 9.18 for cerulenin, while 5.32 for triclosan and 1.72 for orlistat. The TI computed relative to 3T3 cells was 28.64, 7.10 and 2.58 for cerulenin, triclosan and orlistat, respectively. DNA fragmentation analysis suggests that FASN inhibitors induced apoptotic DNA damage in retinoblastoma cells. Thus, FASN inhibition can be an effective strategy in retinoblastoma therapy.

Ophthalmological complications in hepatitis C virus infection: side effect of interferon therapy or a direct role of HCV?

Several clinical studies have demonstrated that retinopathy and ophthalmic complications are features that appear mostly as side effects in HCV patients undergoing interferon (IFN) therapy. Here we underline that HCV itself is also able to modulate genes involved in ocular pathologies. Presently an in vitro model of ocular tissue derived cells infected with HCV is missing. The establishment of such in vitro models would be helpful to better understand the mechanisms through which HCV induces optical pathologies in order to specifically target the causes of ocular disease.

Bibliometric analysis on retinoblastoma literatures in PubMed during 1929 to 2010

AIM

To determine the growth rule and tendency of retinoblastoma (Rb) literature, and to provide the basis for research of diagnosis, treatment and on Rb.

METHODS

Bibliometric analyses were carried out on Rb literatures which contain the descriptors of Rb in their titles or texts from 1929 to 2010 in PubMed database (www.ncbi.nlm.nih.gov/Pubmed). The biomedical journals referring to Rb by using bibliometric indicators were calculated. The principal bibliometric indicators, i.e., Price's and Bradford's laws to the increase or distribution of scientific literature, the participation index of languages and the journals were applied. By means of manual coding, Rb documents were classified according to documents studied and to statistical analysis.

RESULTS

During 1929-2010, there were 16162 literatures in the PubMed database including the word Rb. According to the literature type, it includes Review (n=2026), Randomized Controlled Trial (n=7), Practice guideline (n=3), meta-analysis (n=4), letter (n=215), editorial (n=98), clinical trial (n=115) and others (n=13694). By the statistical analysis, its equation is near power index (y=3.0477x(2.6088), R(2)=0.9666). From 1929 to 2010, Rb literatures in English were primarily dominant (90.71%) and the amount of the literature in Chinese ranked the fourth (1.37%). By searching PubMed, 1420(8.8%) literatures covered were from 41 of 48 ophthalmological, and 406 (2.5%) literatures from 44 of 86 pediatrics journals that correlated with retinoblastoma (SCI-indexed). The data showed that the literatures of Rb were gradually increasing year by year and were approximate near power index during 1929-2010, and the document publishes published mainly in ophthalmological journals, and in English (90.71%), and showing that the study on Rb is a popular subject in the last half century.

CONCLUSION

The literatures of Rb are gradually increasing, mainly English in ophthalmologic journals.

Using epidemiology and genomics to understand osteosarcoma etiology

Osteosarcoma is a primary bone malignancy that typically occurs during adolescence but also has a second incidence peak in the elderly. It occurs most commonly in the long bones, although there is variability in location between age groups. The etiology of osteosarcoma is not well understood; it occurs at increased rates in individuals with Paget disease of bone, after therapeutic radiation, and in certain cancer predisposition syndromes. It also occurs more commonly in taller individuals, but a strong environmental component to osteosarcoma risk has not been identified. Several studies suggest that osteosarcoma may be associated with single nucleotide polymorphisms in genes important in growth and tumor suppression but the studies are limited by sample size. Herein, we review the epidemiology of osteosarcoma as well as its known and suspected risk factors in an effort to gain insight into its etiology.

Epidemiology and Rb1 gene of retinoblastoma

Retinoblastoma (Rb) is the most common eye cancer in children and it can be inherited. Rb is quite rare and originators from the neural retina with a significant genetic component in etiology, which occurs in approximately 1 in every 20 0000 births. In children with the heritable genetic form of Rb, there is a mutation on chromosome 13, called the retinoblastoma 1 (Rb1) gene. Early diagnosis and intervention is critical to the successful treatment of the Rb. The Rb1 gene is the first cloned tumor suppressor gene. As a negative regulator of the cell cycle, Rb1 gene could maintain a balance between cell growth and development through binding to transcription factors and regulating the expression of genes involved in cell proliferation and differentiation. Thus, it is involved in cell cycle, cell senescence, growth arrest, apoptosis and differentiation. We summarized the recent advances on the epidemiology and Rb1 gene of Rb in this review.

Tumor suppressor gene-based nanotherapy: from test tube to the clinic

Cancer is a major health problem in the world. Advances made in cancer therapy have improved the survival of patients in certain types of cancer. However, the overall five-year survival has not significantly improved in the majority of cancer types. Major challenges encountered in having effective cancer therapy are development of drug resistance by the tumor cells, nonspecific cytotoxicity, and inability to affect metastatic tumors by the chemodrugs. Overcoming these challenges requires development and testing of novel therapies. One attractive cancer therapeutic approach is cancer gene therapy. Several laboratories including the authors' laboratory have been investigating nonviral formulations for delivering therapeutic genes as a mode for effective cancer therapy. In this paper the authors will summarize their experience in the development and testing of a cationic lipid-based nanocarrier formulation and the results from their preclinical studies leading to a Phase I clinical trial for nonsmall cell lung cancer. Their nanocarrier formulation containing therapeutic genes such as tumor suppressor genes when administered intravenously effectively controls metastatic tumor growth. Additional Phase I clinical trials based on the results of their nanocarrier formulation have been initiated or proposed for treatment of cancer of the breast, ovary, pancreas, and metastatic melanoma, and will be discussed.

Developmental origins of fusion-negative rhabdomyosarcomas

Rhabdomyosarcomas (RMS) are very heterogeneous tumors that can be divided into three major groups: alveolar rhabdomyosarcoma, embryonal rhabdomyosarcoma, and pleomorphic rhabdomyosarcoma. Concerted efforts over the past a decade have led to an understanding of the genetic underpinnings of many human tumors through genetically engineered models; however, left largely behind in this effort have been rare tumors with poorly understood chromosomal abnormalities including the vast majority of RMS lacking a pathognomonic translocation, i.e. fusion-negative RMS. In this chapter, we review the characteristic genetic abnormalities associated with human RMS and the genetically engineered animal models for these fusion-negative RMS. We explore not only how specific combinations of mutations and cell of origin give rise to different histologically and biologically distinguishable pediatric and adult RMS subtypes, but we also examine how tumor cell phenotype (and tumor "stem" cell phenotype) can vary markedly from the cell of origin.