Lipophilic 2'-O-Acetal Ester RNAs: Synthesis, Thermal Duplex Stability, Nuclease Resistance, Cellular Uptake, and siRNA Activity after Spontaneous Naked Delivery.

The in vivo application of siRNA depends on its cellular uptake and intracellular release, and this is an unsatisfactorily resolved technical hurdle in medicinal applications. Promising concepts directed towards providing efficient cellular and intracellular delivery include lipophilic chemical modification of siRNA. Here we describe chemistry for the production of modified siRNAs designed to display improved transmembrane transport into human cells while preserving the potency of the RNAi-based inhibitors. We report the synthesis and the biochemical and biophysical characteristics of 2'-O-phenylisobutyryloxymethyl (PiBuOM)-modified siRNAs and their impact on biological activity. In the case of spontaneous cellular uptake of naked PiBuOM-modified siRNA, we observed increased target suppression in human cells relative to unmodified or pivaloyloxymethyl (PivOM)-modified siRNA. We provide evidence of improved spontaneous cellular uptake of naked PiBuOM-modified siRNA and of substantial target suppression in human cells in serum-containing medium.

The human TRAM1 locus expresses circular RNAs.

Numerous indirect and in silico produced evidences suggest circular RNAs (circRNA) in mammals while thorough experimental proofs of their existence have rarely been reported. Biological studies of circRNA, however, should be based on experimentally verified circRNAs. Here, we describe the identification of two circRNAs originating from the gene locus of the translocation associated membrane protein 1 (TRAM1). Linear and potentially circular TRAM1-specific transcripts were identified in a transcriptome analysis of urine RNA of bladder cancer (BCa) patients versus healthy donors. Thus, we first focused on the topology of TRAM1-specific transcripts. We describe conclusive experimental evidence for the existence of TRAM1-specific circRNAs in the human BCa cell lines ECV-304 and RT-4. PCR-based methodology followed by cloning and sequencing strongly indicated the circular topology of two TRAM1 RNAs. Further, studies with exon fusion sequence-specific antisense oligonucleotides (asON) and RNase H as well as studies in the use of RNase R contribute to conclusive set of experiments supporting the circular topology of TRAM1 transcripts. On the biological side, TRAM1-specific circRNAs showed low expression levels and minor differences in BCa cell lines while linear TRAM1 transcripts displayed down-regulated expression in the higher cancer stage model ECV-304 versus more differentiated RT-4 cells.

Transcriptome analyses of urine RNA reveal tumor markers for human bladder cancer: validated amplicons for RT-qPCR-based detection.

Non-invasive clinical diagnostics of bladder cancer is feasible via a set of chemically distinct molecules including macromolecular tumor markers such as polypeptides and nucleic acids. In terms of tumor-related aberrant gene expression, RNA transcripts are the primary indicator of tumor-specific gene expression as for polypeptides and their metabolic products occur subsequently. Thus, in case of bladder cancer, urine RNA represents an early potentially useful diagnostic marker. Here we describe a systematic deep transcriptome analysis of representative pools of urine RNA collected from healthy donors versus bladder cancer patients according to established SOPs. This analysis revealed RNA marker candidates reflecting coding sequences, non-coding sequences, and circular RNAs. Next, we designed and validated PCR amplicons for a set of novel marker candidates and tested them in human bladder cancer cell lines. We identified linear and circular transcripts of the S100 Calcium Binding Protein 6 (S100A6) and translocation associated membrane protein 1 (TRAM1) as highly promising potential tumor markers. This work strongly suggests exploiting urine RNAs as diagnostic markers of bladder cancer and it suggests specific novel markers. Further, this study describes an entry into the tumor-biology of bladder cancer and the development of gene-targeted therapeutic drugs.

Oncoprotein 18 is necessary for malignant cell proliferation in bladder cancer cells and serves as a G3-specific non-invasive diagnostic marker candidate in urinary RNA.

BACKGROUND: Urine-based diagnostics indicated involvement of oncoprotein 18 (OP18) in bladder cancer. In cell culture models we investigated the role of OP18 for malignant cell growth. METHODS: We analyzed 113 urine samples and investigated two human BCa cell lines as a dual model: RT-4 and ECV-304, which represented differentiated (G1) and poorly differentiated (G3) BCa. We designed specific siRNA for down-regulation of OP18 in both cell lines. Phenotypes were characterized by cell viability, proliferation, and expression of apoptosis-related genes. Besides, sensitivity to cisplatin treatment was evaluated. RESULTS: Analysis of urine samples from patients with urothelial BCa revealed a significant correlation of the RNA-ratio OP18:uroplakin 1A with bladder cancer. High urinary ratios were mainly found in moderately to poorly differentiated tumors (grade G2-3) that were muscle invasive (stage T2-3), whereas samples from patients with more differentiated non-invasive BCa (G1) showed low OP18:UPK1A RNA ratios. Down-regulation of OP18 expression in ECV-304 shifted its phenotype towards G1 state. Further, OP18-directed siRNA induced apoptosis and increased chemo-sensitivity to cisplatin. CONCLUSIONS: This study provides conclusive experimental evidence for the link between OP18-derived RNA as a diagnostic marker for molecular staging of BCa in non-invasive urine-based diagnostics and the patho-mechanistic role of OP18 suggesting this gene as a therapeutic target.