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Udgivelsesdato: 15.august

Cancer cells secrete soluble factors and various extracellular vesicles, including exosomes, into their tissue microenvironment. The secretion of exosomes is speculated to facilitate local invasion and increase the propensity of tumors to form distant metastases.Here we present a characterization of exosome vesicles from isogenic urothelial carcinoma cell lines, with different metastatic propensity by western blotting, electron microscopy, nanoparticle tracking analysis, dynamic light scattering, and profiling of 671 miRNAs by qRT-PCR. An increase in the number of multivesicular bodies and exosomes was observed for metastatic FL3 cells compared to isogenic non-metastatic T24 cells. The release was significantly inhibited by knockdown of Rab27b and pharmacological inhibition of nsmase2 by GW4869. miRNA profiling was conducted on parental cells and their secreted exosomes. Here, selective export of miR921, 23b, and 224 was observed from metastatic cell lines compared to their non- or low-metastatic isogenic parental cells and primary urothelial cells. Both inhibition of exosome release (Rab27b knockdown, GW4869 treatment) and ectopic overexpression of miR921, 23b, 224 inhibited cellular invasion through matrigel, whereas cellular viability was unaffected.Our results indicate that metastatic urothelial carcinoma cells display altered exosome secretion and -content, which may affect steps of the metastatic cascade such as local invasion.

Multiple transcriptional events take place when normal urothelium is transformed into tumor tissue. These can now be monitored simultaneously by the use of oligonucleotide arrays, and expression patterns of superficial and invasive tumors can be established. Single-cell suspensions were prepared from bladder biopsies (36 normal, 29 tumor). Pools of cells were made from normal urothelium and from pTa grade I and II and pT2 grade III and IV bladder tumors. From these suspensions, and from 10 single-tumor biopsies, labeled cRNA was hybridized to oligonucleotide arrays carrying probes for 6500 genes. The obtained expression data were sorted according to a weighting scheme and were subjected to hierarchical cluster analysis of tissues and genes. Northern blotting was used to verify the array data, and immunohistology was used to correlate between RNA and protein levels. Hierarchical clustering of samples correctly identified the stage using both 4076 genes and a subset of 400 genes covarying with the stages and grades of tumors. Hierarchical clustering of gene expression levels identified several stage-characteristic, functionally related clusters, encoding proteins that were related to cell proliferation, oncogenes and growth factors, cell adhesion, immunology, transcription, proteinases, and ribosomes. Northern blotting correlated well with array data. Immunohistology showed a good concordance between transcript level and protein staining. The study indicates that gene expression patterns may be identified in bladder cancer by combining oligonucleotide arrays and cluster analysis. These patterns give new biological insight and may form a basis for the construction of molecular classifiers and for developing new therapy for bladder cancer.

Udgivelsesdato: September The alpha1,3/4-fucosyltransferases are involved in the synthesis of fucosylated cell surface glycoconjugates. Human alpha1,3/4-fucosyltransferase III, -V, and -VI (hFucTIII, -V, and -VI) contain two conserved C-terminal N-glycosylation sites (hFucTIII: Asn154 and Asn185; hFucTV: Asn167 and Asn198; and hFucTVI: Asn153 and Asn184). In the present study, we have analyzed the functional role of these potential N-glycosylation sites, laying the main emphasis on the sites in hFucTIII. Tunicamycin treatment completely abolished hFucTIII enzyme activity while castanospermine treatment diminished hFucTIII enzyme activity to approximately 40% of the activity of the native enzyme. To further analyze the role of the conserved N-glycosylation sites in hFucTIII, -V, and -VI, we made a series of mutant genomic DNAs in which the asparagine residues in the potential C-terminal N-glycosylation sites were replaced by glutamine. Subsequently, the hFucTIII, -V, and -VI wild type and the mutants were expressed in COS-7 cells. All the mutants exhibited lower enzyme activity than the wild type and elimination of individual sites had different effects on the activity. The mutations did not affect the protein level of the mutants in the cells, but reduced the molecular mass as predicted. Kinetic analysis of hFucTIII revealed that lack of glycosylation at Asn185 did not change the Km values for the oligosaccharide acceptor and the nucleotide sugar donor. The present study demonstrates that hFucTIII, -V, and -VI require N-glycosylation at the two conserved C-terminal N-glycosylation sites for expression of full enzyme activity.