Oestrogen and Antioestrogen Induced Gene Expression

Travers, Maureen T (1987) Oestrogen and Antioestrogen Induced Gene Expression. PhD thesis, University of Glasgow.

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Abstract

The aim of this project was to study the effect of oestrogen and the antioestrogen tamoxifen on the expression of specific genes in the immature rat uterus and MCF-7 human breast cancer cells in order to try and further understand the mechanism of action of these two compounds. In order to do this a cDNA library was constructed using mRNA from 4 hour oestrogen-stimulated rat uteri. This was then screened with cDNA to mRNA from oestrogen stimulated and unstimulated rat uteri in order to isolate clones of oestrogen-regulated mRNAs. Twelve such clones were isolated and the expression of three of these, F4, B11 and E10, together with clones to a number of oncogenes, v-myc, v-Ha-ras, v-Ki-ras and c-sis, the oestrogen-regulated pS2 clone from MCF-7 cells, and an actin clone, p749, were studied in the immature rat uterus and MCF-7 cells in response to oestrogen and tamoxifen. In the immature rat uterus oestrogen caused a biphasic stimulation of expression of total mRNA with peaks at 4 and 16-20 hours after administration and, although the extent of induction was variable, it had a similar effect on all the clones studied, except actin which showed a continual increase from 0-20 hours after administration. Taking into account the slower uptake of tamoxifen, when compared to oestrogen, by uterine cells, and its metabolism to a more active derivative, this compound was found to be agonistic with respect to the induction of all the genes studied except the oestrogen-regulated clone from the rat uterine cDNA library, F4, which showed only one early peak of induction in response to tamoxifen. In MCF-7 human breast cancer cells oestrogen caused a 2-2.5 fold increase in mRNA. levels over control cells between 3 and 36 hours after administration, whereas tamoxifen treatment resulted in no increase in mRNA levels over the first 8 hours, and a decrease to half control level by 36 hours. Oestrogen also stimulated the expression of all the clones studied in this system, except the uterine library clone E10 which did not cross-react with MCF-7 cell RNA, though not to the same extent as in the immature rat uterus. However, the effect of tamoxifen on the amount of total mRNA available from MCF-7 cells meant that only two of the clones, pS2 and p-myc-2, could be studied in full. Of these the level of myc specific RNA was not increased at all but decreased steadily over the 36 hours studied, and although the level of pS2 specific RNA was increased within 1 hour of tamoxifen administration, this increase was only a fraction of that caused by oestrogen at 24 hours, and had fallen to control levels by 36 hours.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Biochemistry, Endocrinology, Genetics
Date of Award: 1987
Depositing User: Enlighten Team
Unique ID: glathesis:1987-77486
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jan 2020 09:07
Last Modified: 14 Jan 2020 09:07
URI: http://theses.gla.ac.uk/id/eprint/77486

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