Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0017636 (glioblastoma)
 18,345 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rsu-1, which was isolated based on its ability to suppress transformation by v-Ras, is a highly conserved gene which shares homology with yeast adenylyl cyclase in the region required for activation by Ras. Genomic DNA clones of human RSU-1 have been isolated and used as a probe for fluorescence in situ hybridization (FISH) to assign RSU-1 to 10p13, confirming the previous results of somatic cell hybrid mapping localizing RSU-1 to chromosome 10. Screening of more than 20 human tumor cell lines for RSU-1 expression revealed that most cell lines contained abundant RSU-1 RNA and protein. However, the p33 RSU-1 protein was undetectable in the U251 glioblastoma cell line and transfection of a rsu-1 expression vector into U251 cells yielded a cell line in which rsu-1 was under the control of a regulatable metallothionein promoter. Addition of Cd2+ to the U251-Rsu-1 transfectant resulted in transcription of rsu-1 RNA and the accumulation of p33 Rsu-1 protein. Appearance of the Rsu-1 protein correlated with a reduction in growth rate of the U251-Rsu-1 transfectant. In addition, reduction in anchorage independent growth and phenotypic alteration in U251-Rsu-1 transfectant agar colonies was observed. Two U251-Rsu-1 transfectant cell lines were non tumorigenic when injected subcutaneously into athymic nude mice. These results, in conjunction with the frequent deletions observed in chromosome 10 in glioblastomas, suggest that RSU-1 loss of function may play a role in the progression of this disease.
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PMID:The Ras suppressor RSU-1 localizes to 10p13 and its expression in the U251 glioblastoma cell line correlates with a decrease in growth rate and tumorigenic potential. 762 54

Previous studies demonstrated that the Ras suppressor, RSU-1, localizes to human chromosome 10p13, a region frequently deleted in high grade gliomas, and that RSU-1 expression inhibited the tumorigenesis of a glioblastoma cell line. We have now examined RNA from human glial tumors for RSU-1 expression by RT-PCR using primers for the 5' and 3' ends of the RSU-1 open reading frame. Analysis of the amplified RSU-1 cDNA demonstrated that in addition to the entire 858 bp RSU-1 open reading frame, a shorter 725 bp RSU-1 fragment was amplified as well. Sequencing of this product revealed that it encoded a RSU-1 cDNA product which was missing a single 133 bp internal exon. This exon-deleted product was found in 30% of the high grade gliomas studied and 2/3 oligodendrogliomas, but not in other CNS tumors, bladder or colon tumors or normal tissue. The exon-deleted RSU-1 product was infrequently detected in RNA from human tumor cell lines. Expression of an HA-tagged form of the deleted RSU-1 protein in transfected Cos 1 cells revealed that the protein was unstable, with a half life of less than 1 h, in contrast to the full length HA-tagged Rsu-1 protein which was stable for more than 4 h. These results suggest that the alternative splicing of the RSU-1 RNA to produce the exon-deleted form constitutes a mechanism for reduction or loss of functional Rsu-1. Because the expression of Rsu-1 can inhibit malignant growth of glioblastoma cells, the depletion of Rsu-1, via the production of the alternatively spliced form of RSU-1, may inhibit growth regulation in tumors.
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PMID:Identification of an alternatively spliced RNA for the Ras suppressor RSU-1 in human gliomas. 1251 Jul 72