Seliciclib (CYC202 or R-roscovitine), a small-molecule cyclin-dependent kinase inhibitor, mediates activity via down-regulation of Mcl-1 in multiple myeloma.

Abstract

Cyclin-dependent kinase (CDK) inhibitors have the potential to induce cell-cycle arrest and apoptosis in cancer cells. Seliciclib (CYC202 or R-roscovitine) is a potent CDK inhibitor currently undergoing phase-2 clinical testing in lung and B-cell malignancies. Here we studied the in vitro cytotoxic activity of seliciclib against multiple myeloma (MM) cells. Our data demonstrate that seliciclib has potent cytotoxicity against MM cells that are both sensitive and resistant to conventional therapy as well as primary MM cells from patients. Cell-cycle and Western blot analysis confirmed apoptosis. Importantly, seliciclib triggered a rapid down-regulation of Mcl-1 transcription and protein expression independent of caspase cleavage. Adherence of MM cells to bone marrow stromal cells (BMSCs) induced increased Mcl-1 expression associated with signal transducer and activator of transcription 3 (STAT3) phosphorylation, which was inhibited in a time- and dose-dependent manner by seliciclib. Furthermore, seliciclib inhibited interleukin 6 (IL-6) transcription and secretion triggered by tumor cell binding to BMSCs. Up-regulation of Mcl-1 expression in cocultures was only partially blocked by neutralizing antibody to IL-6, suggesting alternative mechanisms of Mcl-1 modulation by seliciclib. Finally, combination studies of seliciclib with doxorubicin and bortezomib show in vitro synergism, providing the rationale for testing these drug combinations to improve patient outcome in MM.

• Authors: Noopur Raje, Shaji Kumar, Teru Hideshima, Aldo Roccaro, Kenji Ishitsuka, Hiroshi Yasui, Norihiko Shiraishi, Dharminder Chauhan, Nikhil C Munshi, Simon R Green, Kenneth C Anderson
• Journal: Blood (Blood) Vol. 106 Issue 3 Pg. 1042-7 (Aug 01 2005) ISSN: 0006-4971 [Print] United States
• PMID: 15827128 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• DNA-Binding Proteins
• Interleukin-6
• Myeloid Cell Leukemia Sequence 1 Protein
• Neoplasm Proteins
• Proto-Oncogene Proteins c-bcl-2
• Purines
• STAT3 Transcription Factor
• STAT3 protein, human
• Trans-Activators
• Roscovitine
• Cyclin-Dependent Kinases

Topics

• Antineoplastic Combined Chemotherapy Protocols (pharmacology)
• Apoptosis
• Cell Adhesion
• Coculture Techniques
• Cyclin-Dependent Kinases (antagonists & inhibitors)
• DNA-Binding Proteins (metabolism)
• Down-Regulation (drug effects, genetics)
• Drug Synergism
• Humans
• Interleukin-6 (genetics, metabolism)
• Multiple Myeloma (drug therapy, pathology)
• Myeloid Cell Leukemia Sequence 1 Protein
• Neoplasm Proteins (drug effects, genetics)
• Proto-Oncogene Proteins c-bcl-2 (drug effects, genetics)
• Purines (pharmacology)
• Roscovitine
• STAT3 Transcription Factor
• Stromal Cells (cytology)
• Trans-Activators (metabolism)
• Transcription, Genetic (drug effects)
• Tumor Cells, Cultured