Non-malignant and tumor-derived cells differ in their requirement for p27Kip1 in transforming growth factor-beta-mediated G1 arrest

• Published in: The Journal of biological chemistry Vol. 277; no. 44; pp. 41686 - 41692
• Main Authors: Donovan, Jeffrey C H, Rothenstein, Jeffrey M, Slingerland, Joyce M
• Format: Journal Article
• Language: English
• Published: United States 01.11.2002
• Subjects: CDC2-CDC28 Kinases; Cell Cycle Proteins - analysis; Cyclin D1 - analysis; Cyclin E - analysis; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinase Inhibitor p15; Cyclin-Dependent Kinase Inhibitor p16 - analysis; Cyclin-Dependent Kinases - analysis; G1 Phase - drug effects; Humans; Microfilament Proteins - analysis; Microfilament Proteins - physiology; Muscle Proteins; Phosphoproteins - physiology; Protein-Serine-Threonine Kinases - analysis; Proteins; Retinoblastoma-Like Protein p130; Transforming Growth Factor beta - pharmacology; Tumor Cells, Cultured; Tumor Suppressor Proteins
• ISSN: 0021-9258
• DOI: 10.1074/jbc.M204307200

Transforming growth factor beta (TGF-beta) induces G(1) arrest in susceptible cells by multiple mechanisms that inhibit the G(1) cyclin-dependent kinases (Cdks), including Cdk2, Cdk4, and Cdk6. TGF-beta treatment of early passage finite lifespan human mammary epithelial cells (HMECs) led to an accumulation of p27(Kip1) in cyclin E1-Cdk2 complexes and kinase inhibition. The requirement for p27 in the G(1) arrest by TGF-beta was assessed by transfection of antisense p27 (ASp27) oligonucleotides into TGF-beta-treated HMECs. Despite a reduction in total and cyclin E-Cdk2 bound p27 after ASp27 transfection, HMECs remained arrested in the G(1) phase. Maintenance of the G(1) arrest was accompanied by increased association of the Cdk inhibitor p21(WAF-1/Cip-1) and the retinoblastoma family member p130(Rb2) in cyclin E1-Cdk2 complexes along with kinase inhibition. In contrast to the findings in HMECs, p27 was essential for G(1) arrest by TGF-beta in two tumor-derived lines. ASp27 transfection into two TGF-beta-responsive, cancer-derived lines was not associated with increased compensatory binding of p21 and p130 to cyclin E1-Cdk2, and these cell lines failed to maintain G(1) arrest despite the continued presence of TGF-beta. Progressive cell cycle deregulation leading to impaired checkpoint controls during malignant tumor progression may alter the role of p27 from a redundant to an essential inhibitor of G(1)-to-S phase progression.