Nuclear Localization of Robo is Associated with Better Survival in Bladder Cancer

Circular RNA_0001495 increases Robo1 expression by sponging microRNA-527 to promote the proliferation, migration and invasion of bladder cancer cells

Bladder cancer (BCa) is a heterogeneous disease that poses great threats on public health. Increasing studies have identified the vital functions of circular RNAs (circRNAs) in BCa treatment. Hence, this current study set out to explore the modulatory role of circ_0001495 in BCa development. First, the expression of circ_0001495 was determined by reverse transcription quantitative polymerase chain reaction. Cell biological processes were then analyzed after altering the circ_0001495 expression in T24 cells. Next, interactions among circ_0001495, microRNA-527 (miR-527) and roundabout guidance receptor 1 (Robo1) were investigated by dual luciferase reporter gene assay, RNA pull down assay and FISH assay. Lastly, xenograft tumors in nude mice were established to explore the effect of circ_0001495 in vivo. It was found that circ_0001495 was highly expressed in BCa tissues and cells, and was further correlated with poor prognosis in BCa patients. In addition, circ_0001495 inhibited the activity of miR-527 by acting as a sponge to sponge miR-527, which further elevated the Robo1 expression. Lastly, circ_0001495 was found to promote the proliferation, migration and invasion of BCa cells in vitro through the miR-527/Robo1 axis and promote the growth and metastasis of BCa tumors in vivo. Altogether, findings in our study highlight the promoting role of circ_0001495 in the progression of BCa by increasing Robo1 via sponging miR-527, representing a promising target for BCa management.

Identification of novel drug resistance mechanisms by genomic and transcriptomic profiling of glioblastoma cells with mutation-activated EGFR

AIMS

Epidermal growth factor receptor (EGFR) is not only involved in carcinogenesis, but also in chemoresistance. We characterized U87.MGΔEGFR glioblastoma cells with constitutively active EGFR due to deletion at the ligand binding domain in terms of gene expression profiling and chromosomal aberrations. Wild-type U87.MG cells served as control.

MATERIALS AND METHODS

RNA sequencing and network analyses (Ingenuity Pathway Analysis) were performed to identify novel drug resistance mechanisms related to expression of mutation activated EGFR. Chromosomal aberrations were characterized by multicolor fluorescence in situ hybridization (mFISH) and array comparative genomic hybridization (aCGH).

KEY FINDINGS

U87.MGΔEGFR cells presented much more chromosomal aberrations, amplifications and deletions than wild-type U87.MG cells. Still, both cell lines were near-triploid. Numerous genes were overexpressed in U87.MGΔEGFR cells, some of which have been already linked to drug resistance. PXDN, which is associated with epithelial mesenchymal transition, was the most upregulated gene (901.8-fold). TENM1 was 331.6-fold upregulated, and it was previously reported to modulate neural development. EGFR-AS1 (161.2-fold upregulated) has been reported to increase the EGFR mRNA stability and its expression - in accordance with that of EGFR - was upregulated (85.5-fold). In addition to well-known resistance genes, numerous novel genes and genomic aberrations were identified. ANGPT2 upregulation and CPM downregulation were validated by Western blotting.

SIGNIFICANCE

Transcriptomics and genomics analyses in U87.MGΔEGFR cells unraveled a range of novel drug resistance mechanisms including apoptosis, DNA repair, ferroptosis, glutathione related gene activities, heat shock, oxidative stress, transcription factor activities, which may have important implications for future treatment strategies.

A novel risk score based on a combined signature of 10 immune system genes to predict bladder cancer prognosis

Bladder cancer (BC) is a common internal malignant tumor with a poor prognosis worldwide. There is an urgent need to better understand the pathogenesis and progression of BC and to find useful biomarkers for diagnosis and prognosis. This study was aimed at developing a potential immunogenomic prognostic signature for BC patients. To identify possible immune-system-related genes (IRGs) whose parameters predict the survival of BC patients, we chose 371 BC patients and analyzed differentially expressed IRGs from The Cancer Genome Atlas (TCGA) datasets. We then derived a 10-IRG formula, including MMP9, RBP7, PDGFRA, AHNAK, OAS1, OLR1, RAC3, SLIT2, IGF1, and AGTR1, to estimate BC prognosis. To validate the mRNA levels of these IRGs, we performed quantitative PCR and found that the expression of these genes almost matched the corresponding mRNA expression levels in TCGA. Furthermore, we validated the prognostic value of the new risk model using two external datasets from Gene Expression Omnibus: GSE13507 (n = 165) and GSE32894 (n = 224). Our data pointed to a significant correlation between the risk model and patients' prognosis. Bioinformatic analysis revealed that products of the IRGs have possible effects on tumor immune processes such as an inflammatory response and cytokine-cytokine receptor interaction. Finally, assessment of the clinical value of the immune-system-based risk signature showed that several of these IRGs were differentially expressed between patients with different clinical characteristics: a high risk score positively correlated with female sex, advanced tumor stage, more advanced T stage, and lymph node metastasis. This immunogenomic signature may represents a reliable prognostic tool for BC and can help to design an individualized immunotherapy.

Regulatory mechanisms of Robo4 and their effects on angiogenesis

Roundabout4 (Robo4) is a transmembrane receptor that belongs to the Roundabout (Robo) family of axon guidance molecules. Robo4 is an endothelial-specific receptor that participates in endothelial cell migration, proliferation, and angiogenesis and the maintenance of vasculature homeostasis. The purpose of this review is to summarize and analyze three main mechanisms related to the expression and function of Robo4 during developmental and pathological angiogenesis. In this review, static shear stress and the binding of transcription factors such as E26 transformation-specific variant 2 (ETV2) and Slit3 induce Robo4 expression and activate Robo4 during tissue and organ development. Robo4 interacts with Slit2 or UNC5B to maintain vascular integrity, while a disturbed flow and the expression of transcription factors in inflammatory or neoplastic environments alter Robo4 expression levels, although these changes have uncertain functions. Based on the mechanisms described above, we discuss the aberrant expression of Robo4 in angiogenesis-related diseases and propose antiangiogenic therapies targeting the Robo4 signaling pathway for the treatment of ocular neovascularization lesions and tumors. Finally, although many problems related to Robo4 signaling pathways remain to be resolved, Robo4 is a promising and potentially valuable therapeutic target for treating pathological angiogenesis and developmental defects in angiogenesis.