ISSN:
1573-7039
Keywords:
ESTROGEN
;
PROGESTIN
;
CELL CYCLE
;
CYCLINS
;
CDKs
;
CDK INHIBITORS
;
PRB
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Estrogens and progesterone, acting via theirspecific nuclear receptors, are essential for normalmammary gland development and differentiated function.The molecular mechanisms through which these effects are mediated are not well defined, althoughsignificant recent progress has been made in linkingsteroid hormone action to cell cycle progression. Thisreview summarizes data identifying c-myc and cyclin D1 as major downstream targets of bothestrogenand progestin-stimulated cell cycle progressionin human breast cancer cells. Additionally, estrogeninduces the formation of high specific activity forms of the cyclin E-Cdk2 enzyme complex lacking thecyclin-dependent kinase (CDK)3 inhibitor, p21. Thedelayed growth inhibitory effects of progestins, whichare likely to be prerequisites for manifestation of their function in differentiation, alsoinvolve decreases in cyclin D1 and E gene expression andrecruitment of CDK inhibitors into cyclin D1-Cdk4 andcyclin E-Cdk2 complexes. Thus estrogens and progestins affect CDK function not only by effects oncyclin abundance but also by regulating the recruitmentof CDK inhibitors and, as yet undefined, additionalcomponents which determine the activity of the CDK complexes. These effects of estrogens andprogestins are likely to be major contributors to theirregulation of mammary epithelial cell proliferation anddifferentiation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1018774302092
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