C-mycprotein expression upregulated by 2-(3-estrone-N-ethyl piperazine-methyl) tetracycline in bone.
OBJECTIVE
To study the effect of XW630 on expression of pro-oncogene c-myc in the long bones of fetal mice in vitro for postulating the mechanism by which XW630 exerts its effect on bone.


METHODS
The fetuses of pregnant mice were removed on day 16 of gestation, the long bones of the forelimbs of female fetal mice were freed of muscle and soft tissue and cultured in a specific device for 48 h in BGJb medium treated with 1 x 10(-7), 1 x 10(-8) and 1 x 10(-9) mol.L-1 XW630 in the final medium. After cultured for 48 h, the long bones were harvested and immunohistochemical analysis was performed for determination of c-Myc protein expression in epiphyseal plates. The areas of positive cells in the resting zone, proliferative zone and hypertrophic zone in epiphyseal plate were determined under image analytic system.


RESULTS
When the concentration of XW630 in the medium was 1 x 10(-9) mol.L-1, the area of c-Myc positive cells increased in the proliferative zone compared with 1 x 10(-9) mol.L-1 in the estrone group, significant increase was also observed in the resting zone compared with the control group. When the concentration of XW630 in medium was 1 x 10(-8) or 1 x 10(-7) mol.L-1, stronger expression than that in the control group and the estrone group at the same concentration was observed in each of the three zones.


CONCLUSIONS
The estrogenic effect of XW630 on bone was stronger than that of estrone. XW630 may promote proliferation and differentiation of chondroncytes by promoting c-Myc protein expression in chondroncytes. Thus, endochondral bone formation was enhanced.
Weng
Ling-ling
LL
West China Pharmaceutical College, Sichuan University, Chengdu 610041, China. L.L.weng@263.net
Li
Ling-zhi
LZ
Zhang
Yong-liang
YL
Lou
Rong-liang
RL
Zheng
Hu
H
D000818:Animals; D019902:Chondrocytes / Q000378:metabolism; D046508:Culture Techniques; D004970:Estrone / Q000494:pharmacology; D005260:Female; D005333:Fetus; D051379:Mice; D010879:Piperazines / Q000494:pharmacology*; D011247:Pregnancy; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism*; D013754:Tetracyclines / Q000494:pharmacology*; D014457:Ulna / Q000187:drug effects* / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
C428143:2-(3-estrone-N-ethyl-piperazine-methyl)tetracycline; D010879:Piperazines; D016271:Proto-Oncogene Proteins c-myc; D013754:Tetracyclines; D004970:Estrone