Overexpression of cyclins D1 and D3 during estrogen-induced breast oncogenesis in female ACI rats.
A common feature of human breast oncogenesis is cell cycle deregulation. The expression of cyclins D1 and D3 was examined during estradiol-17beta (E(2))-induced mammary tumorigenesis in female August Copenhagen Irish (ACI) rats. Low serum E(2) levels ( approximately 60-120 pg/ml) were sufficient to induce mammary gland tumors (MGTs) that remarkably resemble human ductal breast cancer (BC) at the histopathologic and molecular levels. Western blot analysis of the E(2)-induced MGTs revealed a marked rise in cyclins D1 (24-fold), D3 (9-fold) and cdk4 (3-fold) expression compared with age-matched untreated controls. Small focal dysplasias with large, pale staining nuclei were commonly seen at 3-3.6 months, large focal dysplasias, including atypical ductal hyperplasia at 3.6-4.3 months, ductal carcinoma in-situ (DCISs) at 4.3-5.0 months, and 100% incidence of invasive ductal BC/frank tumors at 5-6 months were detected after E(2) treatment. Immunohistochemical analysis of serial sections of focal dysplasias, DCISs and invasive ductal carcinomas showed overexpression of cyclins D1, D3, estrogen receptor-alpha (ERalpha) and progesterone receptor (PR). However, cyclin D3 expression, unlike D1, was confined essentially to early pre-malignant lesions (focal dysplasias and DCISs) and primary MGTs with <1-5% of resting and normal hyperplastic breast cells staining positive. The kinase activity for cyclins D1 and D3, using retinoblastoma (Rb) as a substrate, in E(2)-induced MGTs and their binding to cdk4 was significantly elevated. Semi-quantitative reverse transcriptase PCR analysis of the E(2)-induced MGTs exhibited increased expression of cyclins D1 (2.9-fold) and D3 (1.4-fold) mRNA, indicating that their elevated protein expression was due in part to an increase in mRNA transcription. However, when analyzed by quantitative real-time Q-PCR, these genes were not amplified. These data indicate that in female ACI rat mammary glands, E(2)-induced pre-malignant lesions differentially and selectively express cyclins D1 and D3, thus contributing to a distinct growth advantage of these pre-neoplasias relative to E(2)-elicited normal hyperplasia.
Weroha
S John
SJ
Hormonal Carcinogenesis Laboratory, Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160, USA.
Li
Sara Antonia
SA
Tawfik
Ossama
O
Li
Jonathan J
JJ
D000818:Animals; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000503:physiopathology*; D002453:Cell Cycle / Q000502:physiology*; D002471:Cell Transformation, Neoplastic; D019938:Cyclin D1 / Q000096:biosynthesis*; D056743:Cyclin D3; D016213:Cyclins / Q000096:biosynthesis*; D004958:Estradiol / Q000502:physiology*; D005260:Female; D005784:Gene Amplification; D020869:Gene Expression Profiling; D006965:Hyperplasia; D007150:Immunohistochemistry; D015674:Mammary Neoplasms, Animal / Q000503:physiopathology*; D016133:Polymerase Chain Reaction; D011230:Precancerous Conditions / Q000503:physiopathology; D051381:Rats; D011912:Rats, Inbred ACI
C534696:CCND3 protein, human; C534698:Ccnd3 protein, rat; D056743:Cyclin D3; D016213:Cyclins; D019938:Cyclin D1; D004958:Estradiol