Ectopic cyclin D1 overexpression increases chemosensitivity but not cell proliferation in multiple myeloma
We established a myeloma cell line (RPMI8226) with cyclin D1 overexpression in which the transfected cyclin D1 gene was stably expressed. D1 transfectants showed down-regulation of cyclin D2. Cell proliferation analysis did not show any differences among RPMI8226, mock control, and D1 transfectants. The number of S-phase cells increased while the number of G0/G1- and G2/M-phase cells decreased in D1 transfectants, which indicates a prolonged S-phase caused by cyclin D1 transfection. A decreased number of G2/M-phase cells was also detected in myeloma cells of patients with translocation t(11;14)(q13;q32). Western blot analysis revealed an increase in the hyperphosphorylated form of retinoblastoma (Rb) protein in D1 transfectants; however, the expression of p53, p16, Bax, Bad, Bcl-2, and Mcl-1 did not significantly change. Treatment with anti-myeloma drugs (melphalan, dexamethasone, bortezomib and immunomodulatory compounds) induced apoptosis earlier in D1 transfectants compared with RPMI8226 and mock control via the activation of both caspase-8 and -9. However, we could not detect a relationship between cyclin D1 expression and the response to treatment with VAD and bortezomib. Therefore, we assume that high sensitivity to anti-myeloma drugs depends on the duration of the S-phase, but a clinical response might depend on the number of myeloma cells with cyclin D1 overexpression.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Supplementary Data.
No Article Media
Document Type: Research Article
Affiliations: Department of Hematology and Oncology, RIRBM, Hiroshima University, Minami-ku, Hiroshima 734-8553, Japan
Publication date: January 1, 2008
More about this publication?
- The International Journal of Oncology provides an international forum for the publication of the latest, cutting-edge research in the broad area of oncology and cancer treatment. The journal accepts original high quality works and reviews on all aspects of oncology research including carcinogenesis, metastasis, epidemiology, chemotherapy and viral oncology. Through fair and efficient peer review, the journal is dedicated to publishing top tier research in the field, offering authors rapid publication as well as high standards of copy-editing and production. The International Journal of Oncology is published on a monthly basis in both print and early online.
- Editorial Board
- Information for Authors
- Submit a Paper
- Subscribe to this Title
- Information for Advertisers
- Terms & Conditions
- Ingenta Connect is not responsible for the content or availability of external websites