Chemically induced rat mammary tumor treated with tamoxifen showed decreased expression of cyclin D1, cyclin E, and p21(Cip1).
We studied the effects of tamoxifen (TAM) on the growth of 7,12-dimethylbenz(a)anthracene (DMBA)-induced rat mammary tumor and the expression of cyclin D1, cyclin E, p21(Cip1), and estrogen receptors (ER) by performing immunohistochemistry and Western blot analysis. When tumor size reached between 10 and 15mm in the largest dimension, the rats were divided into a DMBA-control group and a DMBA-TAM group. The administration of TAM markedly decreased the tumor development and showed decreased expression of bromodeoxyuridine, cyclin D1, cyclin E, and p21(Cip1) when compared with those of the DMBA-control group; however, a few tumors showed progressive growth in spite of TAM treatment. These tumors had decreased expression of ER. This study suggests that TAM suppresses tumor development through the down-expression of cyclin D1 and cyclin E.
Jang
T J
TJ
Department of Pathology, Dongguk University College of Medicine, #707, Sukjang-dong, Kyongju, Kyongbuk 780-714, South Korea. taejung@mail.dongguk.ac.kr
Park
J H
JH
Cho
M Y
MY
Kim
J R
JR
D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism; D019938:Cyclin D1 / Q000378:metabolism*; D019927:Cyclin E / Q000378:metabolism*; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism*; D005260:Female; D015870:Gene Expression / Q000187:drug effects*; D015674:Mammary Neoplasms, Animal / Q000139:chemically induced / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013629:Tamoxifen / Q000494:pharmacology* / Q000627:therapeutic use; D016896:Treatment Outcome
C493958:Cdkn1a protein, rat; D019927:Cyclin E; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D013629:Tamoxifen; D019938:Cyclin D1; D015127:9,10-Dimethyl-1,2-benzanthracene; D001973:Bromodeoxyuridine