Análise funcional de genes regulados por glicocoeticóides na reversão fenotípica tumoral-normal de células ST1 de glioma de rato

Author(s)

Roberto Becht Flatschart

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ)
• Defense date: 2001-02-20

Examining board members

Mari Cleide Sogayar; Vilma Regina Martins; Carlos Frederico Martins Menck; Luis Fernando Lima Reis; Eugenia Costanzi Strauss

• Advisor: Mari Cleide Sogayar

Abstract

ST1 and P7 cells, isolated in the laboratory from the C6 rat glioma cell line (ARMELIN and ARMELIN, 1983), constitute interesting models for the study of glucocorticoids action showing, respectively, sensibility and resistance to the hormone when observed morphology, doubling time, saturation density, growth in agarose suspension and tumorigenicity in nude mice. ln a previous work, ESTs sequences corresponding to metallothionein 1, metallothionein 2, α-1-acid glycoprotein and the env gene of a endogenous retrovirus were isolated (VALENTINI and ARMELIN, 1996). To prove the involvement of metallothioneins 1 and 2, α-1-acid glycoprotein and env in the observed phenotypical reversion in ST1 cells dealt with hydrocortisone, two different approaches had been used: the inhibition of the expression of these proteins with antisense cDNA constructs and the overexpression of these proteins using inducible vectors. In agarose suspension growth assay, performed with populations of cells transfected with inducible constructs carring the cDNAs in sense and antisense orientations, the growth of the transfected cells, in the absense or the presence of hydrocortisone and / or inducer allowed us to confirm the role of the corresponding proteins in the hydrocortisone-induced phenotypic reversion. The results showed that antisensa transcripts of α-1-acid glycoprotein, metallothionein 2, metallothionein 1 and env inhibited, in greater or minar degree, the effect of hydrocortisone in transfected ST1 cells. On the other hand, induction of Metallothionein 1 and env expression was able to inhibit, partially, the formation of colonies from ST1 and P7 cells transfected with sense constructs. (AU)