PMID: 9185997Jun 1, 1997Paper

All-trans-retinoic acid mediates G1 arrest but not apoptosis of normal human mammary epithelial cells

Cell Growth & Differentiation : the Molecular Biology Journal of the American Association for Cancer Research
Victoria L SeewaldtS J Collins

Abstract

Retinoids mediate the normal growth of a variety of epithelial cells and may play an important role in the chemoprevention of certain malignancies. Loss of retinoic acid (RA) receptor-beta function may be an important event in mammary carcinogenesis, because the majority of breast cancers, in contrast to normal mammary epithelial cells, fail to express this receptor. We previously reported that all-trans-RA mediates G1 arrest as well as apoptosis in certain RAR beta-transduced breast cancer cell lines. We now report the effect of RA on normal human mammary epithelial cells (HMECs), which express functionally active retinoid receptors. We observe that RA induces growth suppression and G1 arrest of these HMECs but find no evidence that RA mediates apoptosis in these normal cell strains. This RA-induced G1 arrest is temporally associated with decreased levels of hyperphosphorylated retinoblastoma protein without any significant changes in c-myc, p53, p21, or p27 expression. Expression of cyclin D1, cyclin-dependent kinase 4, and cyclin E proteins, however, decreased in association with RA-mediated G1 arrest. Our studies suggest that growth inhibition, rather than apoptosis, may be a mechanism by which RA and RA receptors act to pr...Continue Reading

Related Concepts

Related Feeds

Apoptosis in Cancer

Apoptosis is an important mechanism in cancer. By evading apoptosis, tumors can continue to grow without regulation and metastasize systemically. Many therapies are evaluating the use of pro-apoptotic activation to eliminate cancer growth. Here is the latest research on apoptosis in cancer.

Apoptosis

Apoptosis is a specific process that leads to programmed cell death through the activation of an evolutionary conserved intracellular pathway leading to pathognomic cellular changes distinct from cellular necrosis

Cell Checkpoints & Regulators

Cell cycle checkpoints are a series of complex checkpoint mechanisms that detect DNA abnormalities and ensure that DNA replication and repair are complete before cell division. They are primarily regulated by cyclins, cyclin-dependent kinases, and the anaphase-promoting complex/cyclosome. Here is the latest research.