Effects of short-term antiestrogen treatment of primary breast cancer on estrogen receptor mRNA and protein expression and on estrogen-regulated genes

McClelland, Richard Andrew, Manning, D. L., Gee, Julia Margaret Wendy ORCID: https://orcid.org/0000-0001-6483-2015, Anderson, E., Clarke, R., Howell, A., Dowsett, M., Robertson, J. E., Blamey, R. W., Wakeling, A. E. and Nicholson, Robert Ian 1996. Effects of short-term antiestrogen treatment of primary breast cancer on estrogen receptor mRNA and protein expression and on estrogen-regulated genes. Breast Cancer Research and Treatment 41 (1) , pp. 31-41. 10.1007/BF01807034

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Abstract

Effects of the pure antiestrogen ICI182780 and tamoxifen on ER-protein, ER-mRNA, and estrogen-regulated mRNA expression were analysed using matched pretreatment core-cut biopsies and post-treatment mastectomy samples from 43 ER positive human breast cancers. Sixteen controls received either no preoperative treatment (n = 9) (7 days) or placebo (n = 7) (median 21 days) prior to primary surgery. Nineteen patients received ICI182780 6 mg/day (n = 10) or 18 mg/day (n = 9) for 7 days. Eight patients were given preoperative tamoxifen (4 × 40 mg-day 1, 20 mg/day thereafter, median 21 days). ER-protein expression was assessed on pre and post treatment samples by immunocytochemistry. ER, pS2, pLIV1, and actin-mRNA expression was determined by northern analysis on post-treatment samples only. ER-mRNA levels were similar to controls following ICI182780 or tamoxifen treatment. However ER-protein levels were significantly suppressed by ICI182780, particularly at the higher dosage (p = 0.0013). Tamoxifen had no significant effect on ER-protein levels. The ER-mRNA and ER-protein contents of control tumors were linearly related (Spearman r = 0.719, p = 0.006). A similar relationship between pretreatment protein and post ICI182780 treatment mRNA levels was observed (r = 0.652, p = 0.005). However, comparison of post ICI182780 treatment protein and mRNA results shows a loss of linearity through a reduction in protein without concurrent loss of mRNA (r = 0.28, p = 0.257). pS2 mRNA hybridization was lower in ICI182780 treated samples than controls (Mann-Whitney p = 0.035) but was unaffected by tamoxifen. pLIV1 mRNA hybridization was uninfluenced by either treatment. Short term exposure of breast tumors to ICI182780 appears to produce a greater inhibition of estrogen-induced transcriptional events than tamoxifen. These effects appear to occur without a concurrent reduction in ER mRNA levels.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Pharmacy Medicine
Subjects:	R Medicine > RC Internal medicine > RC0254 Neoplasms. Tumors. Oncology (including Cancer) R Medicine > RM Therapeutics. Pharmacology
Uncontrolled Keywords:	antiestrogen - breast cancer - estrogen receptor - estrogen-regulated genes
Publisher:	Springer Verlag
ISSN:	0167-6806
Last Modified:	18 Oct 2022 14:19
URI:	https://orca.cardiff.ac.uk/id/eprint/17151

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