The effect of tamoxifen on tumours induced by cells from a canine mammary carcinoma cell line in athymic nude mice.
Tumours were induced in CBA athymic nude mice by subcutaneous injection of REM 134 cells. These cells were from a continuous line derived from a canine mammary carcinoma and have no detectable oestrogen receptors. In vitro, the anti-oestrogen tamoxifen was growth inhibitory at a concentration of 10(-6) M and adding 10(-8) M oestradiol-17 beta did not reverse this effect. The relative rate of growth of the tumours induced by the cultured cells was the same in male and female mice. Oral tamoxifen at a dose of 1 mg mouse-1 week-1 suppressed the early growth rate significantly and to the same extent in male and female mice; conversely subcutaneous tamoxifen at 2 mg mouse-1 week-1 had only a transient early effect. These results argue against tamoxifen acting solely as an antagonist for oestrogen.
Norval
M
M
Department of Bacteriology, University of Edinburgh Medical School.
Else
R W
RW
Maingay
J
J
D000818:Animals; D002460:Cell Line; D004285:Dogs; D005260:Female; D008325:Mammary Neoplasms, Experimental / Q000503:physiopathology*; D051379:Mice; D008808:Mice, Inbred CBA; D008819:Mice, Nude; D013629:Tamoxifen / Q000494:pharmacology*
D013629:Tamoxifen