Biological and clinical evaluation of Lanreotide (BIM 23014), a somatostatin analogue,in the treatment of advanced breast cancer |
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Authors: | Angelo Di Leo Leonardo Ferrari Emilio Bajetta Cesare Bartoli Giovanni Vicario Daniele Moglia Rosalba Miceli Marina Callegari Aldo Bono |
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Institution: | (1) Medical Research Council Group in Molecular Endocrinology, Centre Hospitalier de l'Université Laval Research Center and Laval University, 2705 Laurier Boulevard, G1V 4G2 Québec, Canada |
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Abstract: | Summary Recently, compounds having pure antiestrogenic activity have become available. In this study, we examined the activity of the new steroidal antiestrogen EM-170 (N-n-butyl, N-methyl-11-(16![prime](/content/k274071k52722g7p/xxlarge8242.gif) -chloro-3 ,17![prime](/content/k274071k52722g7p/xxlarge8242.gif) -dihydroxy-estra-1 ,3 ,5 -(10 )-trien-7![prime](/content/k274071k52722g7p/xxlarge8242.gif) -yl) undecanamide) on the growth of 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary carcinoma stimulated by treatment with estrone (E1), a steroid known to play an important role as precursor of 17 -estradiol (E2), especially in postmenopausal women. Twenty-five days after ovariectomy (OVX), tumor volume in control OVX animals decreased to 51.4 ± 11% of the initial volume; treatment with E1, administered by Silastic implants, stimulated tumor growth to 179 ± 21%. Treatment with the antiestrogen EM-170 at a dose of 200 µg (twice daily) not only completely reversed the stimulatory effect of E1, but also inhibited tumor growth to 30.5 ± 9.6%, an effect that is 41% (P < 0.01 vs OVX control) greater than that of ovariectomy alone. At a relatively low dose of 40 µg (twice daily), 20 days of treatment with EM-170 reversed by 55% the stimulatory effect of E1 (1.0 µg, subcutaneously, twice daily) on tumor growth in OVX animals. On the other hand, the antiestrogen also induced a significant inhibitory effect on 17 -hydroxysteroid dehydrogenase (17 -HSD) activity in the DMBA-induced mammary tumors, an effect that is in agreement with the marked reduction caused by the same treatment on tumor estradiol (E2) levels in E1-treated OVX animals. The present data show that the new steroidal antiestrogen EM-170 exerts a potent inhibitory effectin vivo on E1-stimulated growth of DMBA-induced mammary tumors, an effect that is probably mediated by both its antiestrogenic activity at the receptor level and its inhibitory effect on 17 -HSD, thus inhibiting local E2 formation and facilitating the action of the antiestrogen at the receptor level. |
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Keywords: | breast cancer steroidal antiestrogen pure antiestrogen DMBA tumors estradiol estrone |
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