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| Author(s): |
Theri Leica Degaki
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2006-09-20 |
| Examining board members: |
Mari Cleide Sogayar;
Luiz Roberto Giorgetti de Britto;
Suely Lopes Gomes;
Sueli Mieko Oba Shinjo;
Sandro José de Souza
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| Advisor: | Mari Cleide Sogayar |
| Abstract | |
Gliomas are the most fatal central nervous system tumors and to date, satisfactory results from chemotherapies or surgical interventions are still not available. The ST1 rat glioma cell line is hyper-responsive to treatment with glucocorticoids (GC), undergoing a complete tumoral to normal phenotypic reversion, both in vitro and in vivo. The P7 glioma cell line is resistant to the action of GC. Both cell models are used in our lab to search for targets which are important to understand the origin of tumors and the control of cell proliferation. For the present study, we aimed at: a) cloning and functional characterization of the rat NRP/B gene, which had previously been identified as being induced during GC-treatment of the ST1 cells; b) identification of human genes located at the 22q13 locus, known to be involved in gliomagenesis. The previously unknown cDNA for rat NRP/B was identified, cloned, sequenced, and deposited in the GenBank (Acc. Nº AY669396). It displays brain-specific expression and positive modulation during GC treatment of ST1 cells. The role of NRP/B in the tumoral to normal phenotypic reversion induced by GC was analyzed by its overexpression in ST1 cells. The results suggest that induction of NRP/B partially impairs cell growth in semi-solid substrate and lowers its tumorigenic potential in vivo. Preliminary studies suggest that NRP/B expression is involved in cell cycle progression and in brain and human breast tumors. To identify additional human genes located in the glioma-related 22q13 locus, two strategies were used: a) analysis of the Ludwig - Fapesp Transcriptome Project database to identify mRNAs and ESTs that align to the referred locus and b) analysis of microarray data of differentially expressed genes in ST1 and P7 cells (both treated with GC) that also localize in chromosome 22. To validate the in silico analysis, Q-PCR was used to evaluate the expression of several genes in human brain tumor cell lines and clinical samples, being possible to find some positive correlations between genes at the transcriptional level. Three genes (KIAA1644, SULT4A1 e PARVG) displayed significantly higher expression levels in non-tumoral clinical samples, when compared to their tumor counterparts suggesting their involvement in human glioma progression. A better understanding of the molecular mechanisms by which these genes are involved may contribute with important information to understand the control of cell proliferation and may lead, in the future, to the development of new therapeutical strategies for brain cancer therapy and diagnosis. (AU) | |