期刊
BRITISH JOURNAL OF PHARMACOLOGY
卷 159, 期 3, 页码 650-658出版社
WILEY-BLACKWELL PUBLISHING, INC
DOI: 10.1111/j.1476-5381.2009.00557.x
关键词
TRAM-34; oestrogen; potassium channel; proliferation; MCF-7; cancer
资金
- Nova Scotia Health Research Foundation-Student Research
- Nova Scotia Health Research Foundation
- Natural Sciences and Engineering Research Council of Canada
- Canadian Breast Cancer Foundation-Atlantic
Background and purpose: K+ channels play a role in the proliferation of cancer cells. We have investigated the effects of specific K+ channel inhibitors on basal and oestrogen-stimulated proliferation of breast cancer cells. Experimental approach: Using the mammary adenocarcinoma cell line MCF-7 we assayed cell proliferation by radiolabelled thymidine incorporation in the absence or presence of various K+ channel inhibitors with or without 17 beta-oestradiol. Key results: Inhibitors of K(v)10.1 and K(Ca)3.1 K+ channels suppressed basal proliferation of MCF-7 cells, but not oestrogen-stimulated proliferation. TRAM-34, a specific inhibitor of K(Ca)3.1 channels increased or decreased cell proliferation depending on the concentration. At intermediate concentrations (3-10 mu M) TRAM-34 increased cell proliferation, whereas at higher concentrations (20-100 mu M) TRAM-34 decreased cell proliferation. The enhancement of cell proliferation caused by TRAM-34 was blocked by the oestrogen receptor antagonists ICI182,780 and tamoxifen. TRAM-34 also increased progesterone receptor mRNA expression, decreased oestrogen receptor-alpha mRNA expression and reduced the binding of radiolabelled oestrogen to MCF-7 oestrogen receptor, in each case mimicking the effects of 17 beta-oestradiol. Conclusions and implications: Our results demonstrate that K+ channels K(v)10.1 and K(Ca)3.1 play a role in basal, but not oestrogen-stimulated MCF-7 cell proliferation. TRAM-34, as well as inhibiting K(Ca)3.1, directly interacts with the oestrogen receptor and mimics the effects of 17 beta-oestradiol on MCF-7 cell proliferation and gene modulation. Our finding that TRAM-34 is able to activate the oestrogen receptor suggests a novel action of this supposedly specific K+ channel inhibitor and raises concerns of interpretation in its use.
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