Integrated Analysis of Dysregulated miRNA-gene Expression in HMGA2-silenced Retinoblastoma Cells

Ophthalmic features of Lamb-Shaffer syndrome: a case series

Lamb-Shaffer syndrome (LSS) is a rare neurodevelopmental disorder, genetically diagnosed in fewer than 100 individuals worldwide. We present a case series of 6 pediatric patients with LSS and describe its ophthalmic manifestations. Strabismus was present in 5 patients, with exotropia being most common. All subjects had significant refractive errors; 5 had astigmatism of at least 2 D. All patients had optic nerve abnormalities, including pallor (4), hypoplasia (2), and anomalous appearance (1), with retinal nerve fiber layer thinning demonstrated in a single subject. Other ophthalmic disorders detected were ptosis (1), nasolacrimal duct obstruction (1), and nystagmus (2).

3' UTR-truncated HMGA2 overexpression induces non-malignant in vivo expansion of hematopoietic stem cells in non-human primates

Vector-mediated mutagenesis remains a major safety concern for many gene therapy clinical protocols. Indeed, lentiviral-based gene therapy treatments of hematologic disease can result in oligoclonal blood reconstitution in the transduced cell graft. Specifically, clonal expansion of hematopoietic stem cells (HSCs) highly expressing HMGA2, a chromatin architectural factor found in many human cancers, is reported in patients undergoing gene therapy for hematologic diseases, raising concerns about the safety of these integrations. Here, we show for the first time in vivo multilineage and multiclonal expansion of non-human primate HSCs expressing a 3' UTR-truncated version of HMGA2 without evidence of any hematologic malignancy >7 years post-transplantation, which is significantly longer than most non-human gene therapy pre-clinical studies. This expansion is accompanied by an increase in HSC survival, cell cycle activation of downstream progenitors, and changes in gene expression led by the upregulation of IGF2BP2, a mRNA binding regulator of survival and proliferation. Thus, we conclude that prolonged ectopic expression of HMGA2 in hematopoietic progenitors is not sufficient to drive hematologic malignancy and is not an acute safety concern in lentiviral-based gene therapy clinical protocols.

circRNA-miRNA-mRNA network in age-related macular degeneration: From construction to identification

The aim of the present study was to investigate the pathogenesis of age-related macular degeneration (AMD) by constructing a regulatory circRNA-miRNA-mRNA network. By adjusting the P value to <0.05 and the absolute log value of fold change to >0.25, 2920 and 1057 differentially expressed mRNAs were identified from GSE50195 and GSE29801, respectively. Based on a literature review, Starbase database analysis, and RNA hybrid assays, we obtained 77 miRNA-mRNA and 331 circRNA-miRNA pairs. After combining these pairs, we constructed a circRNA-miRNA-mRNA network possessing 303 circRNA nodes, 4 miRNA nodes, 51 mRNA nodes, and 408 edges. By utilizing protein-protein network analysis, the MCODE algorithm, and the highest degree of circRNA node, we identified the regulatory axis of hsa_circRNA7329/hsa-miR-9/SCD. Hsa_circRNA7329 may regulate SCD through hsa-miR-9 to promote macrophage-mediated inflammation and pathologic angiogenesis, which lead to AMD development. However, the underlying details require further investigation.

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.

MiR-25-3p promotes malignant phenotypes of retinoblastoma by regulating PTEN/Akt pathway

Aberrant expression of microRNAs plays an important role in the pathogenesis and progression of retinoblastoma. MiR-25, a member of the miR-106b˜25 cluster, has been reported to be abnormally expressed in retinoblastoma, but the exact role of it remains unclear. In our study, we found that miR-25-3p was upregulated in retinoblastoma tissues and cell lines. Enforced expression of miR-25-3p in retinoblastoma cell line WERI-RB-1 increased cell growth, colony formation, anchorage-independent growth, cell migration and invasion in vitro and tumor xenograft growth in vivo. In contrast, inhibited miR-25-3p expression in retinoblastoma cell line Y79 suppressed cell growth, colony formation, anchorage-independent growth, cell migration and invasion. Through luciferase reporter assay, we found that phosphatase and tensin homolog (PTEN) was a direct target of miR-25-3p. This was verified by western blot that miR-25-3p overexpression suppressed PTEN and activated Akt signaling. In addition, miR-25-3p was found to promote epithelial-mesenchymal transition (EMT) of WERI-RB-1 cells through PTEN/Akt pathway. Western blot analysis revealed that miR-25-3p overexpression increased Vimentin and Snail expression, and suppressed E-cadherin expression, but this could be reversed by restoring PTEN. Moreover, LY294002 treatment or restoring PTEN expression abolished the effects of miR-25-3p on cell invasion, colony formation and anchorage-independent growth in vitro and tumor xenograft growth in vivo. Taken together, our results suggested that miR-25-3p promotes malignant transformation of retinoblastoma cells by suppressing PTEN.

Role of High-mobility Group Protein A Isoforms and Their Clinicopathologic Significance in Primary Retinoblastoma

BACKGROUND

High-mobility group proteins A (HMGA) are more abundant in rapidly dividing and transformed cells. These are a group of proteins regulating tumorigenesis and tumor invasion. Increased expression of HMGA1 and HMGA2 has been reported in various benign and malignant tumors. The aim of the present study was to analyze expression of HMGA1 and HMGA2 proteins in retinoblastoma.

METHODS

Protein expression of HMGA1 and HMGA2 in 80 formalin-fixed retinoblastoma tissues was performed by immunohistochemistry, and their mRNA expressions were analyzed on 40 fresh primary enucleated retinoblastoma samples by semiquantitative reverse transcription polymerase chain reaction. Results were then correlated with clinicopathologic parameters.

RESULTS

Immunohistochemical analysis of HMGA1 and HMGA2 was seen in 56.25% and 58.75% of retinoblastoma cases, respectively. mRNA expressions of HMGA1 and HMGA2 was found to be 57.55% and 62.5%, respectively. The mRNA results correlated well with immunostaining results. Expression of both HMGA1 and HMGA2 was significantly associated with choroidal invasion and poor tumor differentiation.

CONCLUSIONS

HMGA1 and HMGA2 proteins may contribute to tumorigenesis of Rb. Expression of HMGA1 and HMGA2 predicts poor prognosis and could serve as a therapeutic target in the management of RB. Further experiments are needed to determine the role of these proteins as therapeutic targets in tumorigenesis.

Overexpression of miR-194 Reverses HMGA2-driven Signatures in Colorectal Cancer

Colorectal cancer (CRC) is one of the leading causes of cancer death worldwide with increasing incidence and mortality in developed countries. Oncogenes and microRNAs regulate key signaling pathways in CRC and are known to be deregulated. Oncogenic transcriptional regulator high-mobility group AT-hook 2 (HMGA2) participates in the transformation of several cancers including CRC and exhibits strong correlation with poor prognosis and distal metastasis. Evidence of HMGA2 and its co-regulated miRs contributing to tumor progression remains to be clarified.

METHODS

We performed gene-set enrichment analysis on the expression profiles of 70 CRC patients and revealed HMGA2 correlated genes that are targeted by several miRs including miR-194. To eliminate the oncogenic effects in HMGA2-driven CRC, we re-expressed miR-194 and found that miR-194 functions as a tumor suppressor by reducing cell proliferation and tumor growth in vitro and in vivo.

RESULTS

As a direct upstream inhibitory regulator of miR-194, overexpression of HMGA2 reduced miR-194 expression and biological activity, whereas re-expressing miR-194 in cells with high levels of HMGA2 impaired the effects of HMGA2, compromising cell survival, the epithelial-mesenchymal transition process, and drug resistance.

CONCLUSION

Our findings demonstrate that novel molecular correlations can be discovered by revisiting transcriptome profiles. We uncover that miR-194 is as important as HMGA2, and both coordinately regulate the oncogenesis of CRC with inverted behaviors, revealing alternative molecular therapeutics for CRC patients with high HMGA2 expression.

Targeting HMGA2 in Retinoblastoma Cells in vitro Using the Aptamer Strategy

High-mobility group A2 (HMGA2) protein regulates retinoblastoma (RB) cancer cell proliferation. Here, a stable phosphorothioate-modified HMGA2 aptamer was used to block HMGA2 protein function in RB cells. HMGA2-aptamer internalisation in RB cells (Y79, Weri Rb1) and non-neoplastic human retinal cells (MIO-M1) were optimised. Aptamer induced dose-dependent cytotoxicity in RB cancer cells (0.25-1.5 µM). Increased expression of TGFβ, SMAD4, CDH1, BAX, CASP 3, PARP mRNA and decreased SNAI1, Bcl2 mRNA levels in aptamer-treated RB cells suggests the activation of TGFβ-SMAD4-mediated apoptotic pathway. Synergistic effect with etoposide was observed in aptamer treated RB cells (p value ≤0.05). No significant toxicity was observed in non-neoplastic retinal cells.

Genome-wide analysis of microRNA and mRNA expression signatures in cancer

Cancer is an extremely diverse and complex disease that results from various genetic and epigenetic changes such as DNA copy-number variations, mutations, and aberrant mRNA and/or protein expression caused by abnormal transcriptional regulation. The expression profiles of certain microRNAs (miRNAs) and messenger RNAs (mRNAs) are closely related to cancer progression stages. In the past few decades, DNA microarray and next-generation sequencing techniques have been widely applied to identify miRNA and mRNA signatures for cancers on a genome-wide scale and have provided meaningful insights into cancer diagnosis, prognosis and personalized medicine. In this review, we summarize the progress in genome-wide analysis of miRNAs and mRNAs as cancer biomarkers, highlighting their diagnostic and prognostic roles.

The bone marrow metastasis niche in retinoblastoma

BACKGROUND

Retinoblastoma (Rb) is a progressive cancer which mainly occurs in children, and which is caused by different genetic or epigenetic alterations that lead to inactivation of both alleles of the RB1 gene. Hereditary and non-hereditary forms of Rb do exist, and the hereditary form is associated with an increased risk of secondary malignancies. Metastasis to distant organs is a critical feature of many tumors, and may be caused by various molecular alterations at different stages. Recognition of these alterations and, thus, insight into the processes underlying the development of metastases may result in novel preventive as well as effective targeted treatment options. Rb is associated with metastases to various organs and tissues, including the bone marrow (BM).

METHODS

Here, we provide an overview of mutations and other molecular changes known to be involved in Rb development and metastasis to the BM. This overview is based on a literature search ranging from 1990 to 2015.

CONCLUSIONS

The various BM metastasis-related molecular changes identified to date may be instrumental for a better diagnosis, prognosis and classification of Rb patients, as well as for the development of novel comprehensive (targeted) therapies.