Deregulated expression of cyclin D1 and other cell cycle-related genes in carcinogen-induced rat mammary tumors.
Dysregulation of cyclin expression has been reported for several human malignancies, including breast cancer. To further investigate the role of cyclin genes in mammary tumorigenesis we analyzed the expression of cyclins D1, E and A and other cell cycle-related proteins in a series of nine N-methyl-N-nitrosourea-induced primary rat mammary tumors. Western blot analysis revealed a 10- to 15-fold increase in the level of cyclin D1 protein in most (7/9) of the tumors, when compared with normal rat mammary gland. The two tumors that did not show this increase also displayed negligible levels of the retinoblastoma protein. A moderate increase, 1.5- to 2-fold, in the level of cyclin E was observed in four tumors and three tumors displayed abnormal low molecular weight cyclin E-related proteins. None of the tumors showed amplification of the cyclin D1 or E genes when studied by Southern blot analysis. All nine tumors showed a 2- to 6-fold increase in the level of cyclin A protein. Most of the tumors also displayed a marked increase in levels of the CDK2 and CDK4 proteins. These changes did not appear to be simply a consequence of increased cell proliferation, as assessed by proliferating cell nuclear antigen analysis. Thus, aberrant expression of cyclins and other cyclin-related genes occurs frequently in mammary tumorigenesis in both rodents and humans.
Sgambato
A
A
Columbia-Presbyterian Cancer Center 10032, USA.
Han
E K
EK
Zhang
Y J
YJ
Moon
R C
RC
Santella
R M
RM
Weinstein
I B
IB
D000818:Animals; D042846:CDC2-CDC28 Kinases; D002273:Carcinogens / Q000633:toxicity*; D002453:Cell Cycle / Q000502:physiology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D019938:Cyclin D1; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4; D018844:Cyclin-Dependent Kinases / Q000235:genetics; D016213:Cyclins / Q000235:genetics*; D018283:Cystadenocarcinoma, Papillary / Q000139:chemically induced / Q000201:enzymology / Q000235:genetics*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D016147:Genes, Tumor Suppressor / Q000187:drug effects; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000201:enzymology / Q000235:genetics*; D008770:Methylnitrosourea / Q000633:toxicity*; D015513:Oncogene Proteins / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D011518:Proto-Oncogene Proteins; D051381:Rats; D017207:Rats, Sprague-Dawley
D002273:Carcinogens; D016213:Cyclins; D015513:Oncogene Proteins; D011518:Proto-Oncogene Proteins; D019938:Cyclin D1; D008770:Methylnitrosourea; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495892:Cdk2 protein, rat; C495903:Cdk4 protein, rat; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4; D018844:Cyclin-Dependent Kinases