Tamoxifen induces p21WAF1 and p27KIP1 expression in estrogen receptor-negative lung cancer cells
| Autor: | Lea-Yea Chuang, Wen-Chun Hung, Te-Hsiu Lee |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
Cyclin-Dependent Kinase Inhibitor p21
Cancer Research medicine.medical_specialty Cyclin E Lung Neoplasms Antineoplastic Agents Hormonal Transcription Genetic Estrogen receptor Cell Cycle Proteins Biology medicine.disease_cause Retinoblastoma Protein Cyclin-dependent kinase Internal medicine Carcinoma Non-Small-Cell Lung Cyclins Genetics medicine Tumor Cells Cultured Cytotoxic T cell Humans Molecular Biology Estrogen receptor beta Kinase Tumor Suppressor Proteins G1 Phase Stimulation Chemical Neoplasm Proteins Gene Expression Regulation Neoplastic Tamoxifen Endocrinology Receptors Estrogen Cancer cell biology.protein Cancer research Carcinogenesis Microtubule-Associated Proteins Cell Division Cyclin-Dependent Kinase Inhibitor p27 |
| Zdroj: | Oncogene. 18(29) |
| ISSN: | 0950-9232 |
| Popis: | Tamoxifen (Tam), besides its action as an anti-estrogen, also inhibits cell proliferation of estrogen receptor (ER)-negative cancer cells by an unknown mechanism. In this study, we used ER-negative lung cancer cells to clarify such ER-independent inhibitory effect of Tam. We found that Tam induced G1 growth arrest in these cells. However, our results indicated that the expression of G1 cyclins (including D1, 2, 3 and E) was not regulated by Tam in these lung cancer cells. Additionally, the protein levels of G1 acting cyclin-dependent kinases (CDKs), CDK2, 4 and 6, was unaltered in Tam-treated lung cancer cells with the exception of CDK2 expression in H322 cells which was attenuated by Tam in a cell line-specific manner. We next examined the effect of Tam on the expression of cyclin-dependent kinase inhibitors (CDKIs) and our results demonstrated that the expression of p21WAF1 and p27KIP1, but not p57KIP2, was strongly activated by Tam in these cells. The amounts of p21WAF1 and p27KIP1 co-immunoprecipitated with cyclin E were obviously increased after Tam treatment and reduced activity of cyclin E-associated kinases and accumulation of hypo-phosphorylated retinoblastoma (Rb) protein were clearly detected in Tam-incubated cells. No consentaneous induction of CDKIs was found when ER-negative lung cancer cells were incubated with cytotoxic drugs, cisplatin and etoposide, this indicates that enhancement of CDKI expression is not a non-specific effect of Tam. We also found that Tam may up-regulate p21WAF1 expression via transcription activation. Considered together, these results suggest that Tam-induced growth inhibition in ER-negative lung cancer cells is associated with induction of p21WAF1 and p27KIP1. |
| Databáze: | OpenAIRE |
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