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Effectiveness of steroid and imidazole drugs in inhibiting aromatase activity
147s
D-015 EFFECTIVENESS OF STEROID AND IMI~AZOLE DRUGS IN INHIBITING AROMATAS~ ACTIVITY. Jawny J., Eiermann W. Frauenkllnik im Klinikum Groghadern, Mtinchen We examined two principles in order to block aromatase activity. Human placental microsoms (4-5 mg) were incubated with lB2i3-3H-androstenedione or -testosterone (12.5 nM/10.2 nM) and 1-2 mM NADPH for 2-24 h at 37°C. The test depends on the release of tritlated water after aromatization. To determine the relative potency of the steroids, imidazole antlmycotics and aminoglutethlmid to inhibit aromatase activity, we measured the activity in the presence of increasing amounts (1 FM - 1 mM) of these compounds. The concentrations requlred to achieve 50% inhibition of aromatase activity were (PM): 1. testosterone Q-7/5.4; 2. androstenedione 6.0/6.7; 3. androstatrienedione 9.'1/8.9; 4. ethisterone 13.3/15; 5. androstenetrione 179/375.8; 6. estradiol 933.3/1778.3; 7. hydroxyandrostened~one~ no effect; 8. clotrimazole 6.7/5.6; 9. miconazole 22.2Y34.5; 10. aminoglutethlm~d 61.8/120.5. Cyto~hrom-P-450 coenzyme blockers of aromatase such as imidazole antimycotlcs (8, 9) exhibit the same potency as androgenic (l-4) agents which compete for the substrate binding site. Both groups showed a better effect than amlnoglutethlmid (10). Further incorporation of 0x0-(5) or hydroxy-(7) groups reduce the androgenlc affinity for the active site. The results suggest that serious consideration should be given to the evaluation of new steroid and imidazol agents as inhibitors of estrogen biosynthesis in situations that require suppression of estrogen formation. D-017 LONG-TERN TAMOXIFEN THERAPY OF ATHYMEC MICE IMPLANTED WITH MCF-7 TUMORS: TUMORISTATIC ACTION AND COMPLETE ANTIESTROGENIC ACTION IN THE MOUSE UTERUS. Jordan V.C. and Gottardis M.M. Department of Human Oncology, University of Wisconsin Clinical Cancer Center, Madison, Wisconsin 53792 USA The breast cancer cell line MCF-7 was innoculated (107 cells) into the axillary region of athymic mice and grew into solid tumors with implantation of sustained-releaseestrogen pallets (1.7 mg estradiol in cholesterol &week release). Tumors did not grow in ovarieetomizedmice without estrogen. Tumors could be serially transplanted (5 times); these retained their estrogen dependency for growth and the growth curves remained consistent. The technique provided a tumor "pool" for therape tic experiments. Tamoxifen (5 mg in cholesterol 4-week release) inhibited the binding of [f; HJestradiol in MCF-7 tumors and athymic mouse uterus. Tamoxlfen inhibited estradiol-stimulatedtumor growth but did not stimulate tumor growth when administered alone. Nevertheless, uterine weight increased four-fold. Long-term tamoxifen treatment (6 months) of athymic mice with tumor implants or small (0.2 cm2) tumors did not cause tumor growth. However, tumor growth could be reactivated by estradiol. Eight weeks of treatment caused nearly all the tumora to regrow and each had detectable estrogen and progesterone receptors. In contrast, estradfol did not cause the uterus to grow in mice treated with tamoxifen for 6 months, whereas animals previously not exposed to tamoxifen had a seven-fold increase in uterine wet weight. These results illustrate the target site specifically of tamoxifen and the differential control mechanisms for growth in normal and neoplastfc tissue. Supported by NIH grant POl-20432.
D-018 EFFECT
OF A NEW AROMATASE
7,12_DIMETHYLBENZ-
INHIBITOR
Ia!-ANTHRACENE
(SH4891 ON THE GROWTH
OF RAT MAMMARY
TUMORS
INDUCED
BY
(DMBA)
Nishino Y. and El Etreby M.F. Research
Laboratories
of Schering
AG, Berlin(West)
and Bergkamen,
Federal
Republic
of Germany
(SH489) is a specific inhibitor of the estrogen l-Methyl-androsta-1,4-diene-3,17_dione in vitro and in vivo. Inhibitors of aromatase may offer a promising method for biosynthesis, therapeutic control of estrogen-sensitive tumors in man. In the present study, therefore, we are interested to investigate the influence of SH489 on the growth of estrogen-sensitive mammary tumors. induced in 45 - 47 days old female Spra ue-Dawle Method: Tumors were
oral administration of 20 mg DMDA. When a tumor reached about 1.4 cm in d%aZ&bythZ
~~~Z~~
at ment of animals was initiated, and ovariectomy was done. The tumor size was ditermined with a daily dose intervals for 4 weeks. Intact animals were treated subcutaneously week1 (4-OHA) or the vehicle alone. mgjkg of SH489 or 4-Hydroxy-4-androstene-3,17-dione B of 3 Castrated animals were treated with a daily dose of 9 mg/kg of 19-Hydroxy-testosterone (1;,9-;T&with and without SH489 (30 mg/kg) or the vehicle alone. In intact rats treated with SH489, tumor growth was distinctly less than that in controls,' and the tumor size did not markedly changed during the treatment. SH489 caused a remission in 24 % of tumors at the end of the treatment for 4 weeks. 4-OHA was more effective in 65 % of tumors after 4 weeks of the in suppressing tumor growth, showing a remission When castrated rats were treated with 19-OHT, the decrease in tumor size was treatment. The simultaneous administration of and tumor growth was slightly stimulated. inhibited, SH489 to castrated rats treated with 19-OHT led to a remarkable decrease in tumor size and to a remission in 85 % of tumors. Conclusion: The present results indicate that SH489 is able to inhibit the estrogendependent growth of DMBA-induced mammary tumors in rats.
D-015 EFFECTIVENESS OF STEROID AND IMI~AZOLE DRUGS IN INHIBITING AROMATAS~ ACTIVITY. Jawny J., Eiermann W. Frauenkllnik im Klinikum Groghadern, Mtinchen We examined two principles in order to block aromatase activity. Human placental microsoms (4-5 mg) were incubated with lB2i3-3H-androstenedione or -testosterone (12.5 nM/10.2 nM) and 1-2 mM NADPH for 2-24 h at 37°C. The test depends on the release of tritlated water after aromatization. To determine the relative potency of the steroids, imidazole antlmycotics and aminoglutethlmid to inhibit aromatase activity, we measured the activity in the presence of increasing amounts (1 FM - 1 mM) of these compounds. The concentrations requlred to achieve 50% inhibition of aromatase activity were (PM): 1. testosterone Q-7/5.4; 2. androstenedione 6.0/6.7; 3. androstatrienedione 9.'1/8.9; 4. ethisterone 13.3/15; 5. androstenetrione 179/375.8; 6. estradiol 933.3/1778.3; 7. hydroxyandrostened~one~ no effect; 8. clotrimazole 6.7/5.6; 9. miconazole 22.2Y34.5; 10. aminoglutethlm~d 61.8/120.5. Cyto~hrom-P-450 coenzyme blockers of aromatase such as imidazole antimycotlcs (8, 9) exhibit the same potency as androgenic (l-4) agents which compete for the substrate binding site. Both groups showed a better effect than amlnoglutethlmid (10). Further incorporation of 0x0-(5) or hydroxy-(7) groups reduce the androgenlc affinity for the active site. The results suggest that serious consideration should be given to the evaluation of new steroid and imidazol agents as inhibitors of estrogen biosynthesis in situations that require suppression of estrogen formation. D-017 LONG-TERN TAMOXIFEN THERAPY OF ATHYMEC MICE IMPLANTED WITH MCF-7 TUMORS: TUMORISTATIC ACTION AND COMPLETE ANTIESTROGENIC ACTION IN THE MOUSE UTERUS. Jordan V.C. and Gottardis M.M. Department of Human Oncology, University of Wisconsin Clinical Cancer Center, Madison, Wisconsin 53792 USA The breast cancer cell line MCF-7 was innoculated (107 cells) into the axillary region of athymic mice and grew into solid tumors with implantation of sustained-releaseestrogen pallets (1.7 mg estradiol in cholesterol &week release). Tumors did not grow in ovarieetomizedmice without estrogen. Tumors could be serially transplanted (5 times); these retained their estrogen dependency for growth and the growth curves remained consistent. The technique provided a tumor "pool" for therape tic experiments. Tamoxifen (5 mg in cholesterol 4-week release) inhibited the binding of [f; HJestradiol in MCF-7 tumors and athymic mouse uterus. Tamoxlfen inhibited estradiol-stimulatedtumor growth but did not stimulate tumor growth when administered alone. Nevertheless, uterine weight increased four-fold. Long-term tamoxifen treatment (6 months) of athymic mice with tumor implants or small (0.2 cm2) tumors did not cause tumor growth. However, tumor growth could be reactivated by estradiol. Eight weeks of treatment caused nearly all the tumora to regrow and each had detectable estrogen and progesterone receptors. In contrast, estradfol did not cause the uterus to grow in mice treated with tamoxifen for 6 months, whereas animals previously not exposed to tamoxifen had a seven-fold increase in uterine wet weight. These results illustrate the target site specifically of tamoxifen and the differential control mechanisms for growth in normal and neoplastfc tissue. Supported by NIH grant POl-20432.
D-018 EFFECT
OF A NEW AROMATASE
7,12_DIMETHYLBENZ-
INHIBITOR
Ia!-ANTHRACENE
(SH4891 ON THE GROWTH
OF RAT MAMMARY
TUMORS
INDUCED
BY
(DMBA)
Nishino Y. and El Etreby M.F. Research
Laboratories
of Schering
AG, Berlin(West)
and Bergkamen,
Federal
Republic
of Germany
(SH489) is a specific inhibitor of the estrogen l-Methyl-androsta-1,4-diene-3,17_dione in vitro and in vivo. Inhibitors of aromatase may offer a promising method for biosynthesis, therapeutic control of estrogen-sensitive tumors in man. In the present study, therefore, we are interested to investigate the influence of SH489 on the growth of estrogen-sensitive mammary tumors. induced in 45 - 47 days old female Spra ue-Dawle Method: Tumors were
oral administration of 20 mg DMDA. When a tumor reached about 1.4 cm in d%aZ&bythZ
~~~Z~~
at ment of animals was initiated, and ovariectomy was done. The tumor size was ditermined with a daily dose intervals for 4 weeks. Intact animals were treated subcutaneously week1 (4-OHA) or the vehicle alone. mgjkg of SH489 or 4-Hydroxy-4-androstene-3,17-dione B of 3 Castrated animals were treated with a daily dose of 9 mg/kg of 19-Hydroxy-testosterone (1;,9-;T&with and without SH489 (30 mg/kg) or the vehicle alone. In intact rats treated with SH489, tumor growth was distinctly less than that in controls,' and the tumor size did not markedly changed during the treatment. SH489 caused a remission in 24 % of tumors at the end of the treatment for 4 weeks. 4-OHA was more effective in 65 % of tumors after 4 weeks of the in suppressing tumor growth, showing a remission When castrated rats were treated with 19-OHT, the decrease in tumor size was treatment. The simultaneous administration of and tumor growth was slightly stimulated. inhibited, SH489 to castrated rats treated with 19-OHT led to a remarkable decrease in tumor size and to a remission in 85 % of tumors. Conclusion: The present results indicate that SH489 is able to inhibit the estrogendependent growth of DMBA-induced mammary tumors in rats.