title: Roscovitine regulates invasive breast cancer cell (MDA-MB231) proliferation and survival through cell cycle regulatory protein cdk5.
abstract: Roscovitine, a purine analogue, has been considered for the treatment of cancer. Anti-cancer therapeutic efficacy is being evaluated in clinical trials. However, the mechanisms remain unclear. In the present study, cyclic-dependent kinase 5 (cdk5) proved to be a molecular target for roscovitine-triggered apoptosis for highly invasive breast cancer cell death. Because our previous studies have shown a potential role of cdk5 in endothelial cell proliferation/apoptosis [Sharma, M.R., Tuszynski, G.P., Sharma, M.C. (2004). Angiostatin-induced inhibition of endothelial cell proliferation/apoptosis is associated with the down-regulation of cell cycle regulatory protein cdk5. J. Cell Biochem. 91, 398-409], here we not only demonstrate first that Cdk5, p35, and p25 proteins were all expressed in invasive breast cancer cells MDA-MB231 but also showed that cdk5 expression regulates MDA-MB231 cell proliferation. In addition, potent mitogen bFGF up-regulates cdk5 expression. Roscovitine specifically inhibits cdk5 expression/activity in a dose-dependent manner with concomitant inhibition of MDA-MB231 cell proliferation and induction of apoptosis. By contrast, the roscovitine analog olomoucine, a specific inhibitor of cdk4, failed to affect MDA-MB231 cell proliferation and apoptosis which implies the specific involvement of cdk5 in roscovitine-triggered cell death/proliferation. Additionally, roscovitine-mediated inhibition of proliferation is irreversible. These data suggest that cdk5 may have a significant role in the regulation of breast cancer cell proliferation and apoptosis and extend beyond its role in neurogenesis. These results suggest that Cdk5 is a novel player in roscovitine-triggered breast cancer cell apoptosis and inhibition of proliferation, therefore, may be a potential therapeutic target.
authors.affiliation: Department of Surgery, Drexel University College of Medicine, Philadelphia, PA 19102, USA.
authors.forename: Shaun
authors.initials: S
authors.lastname: Goodyear
authors.forename: Mahesh C
authors.initials: MC
authors.lastname: Sharma
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D051360:Cyclin-Dependent Kinase 5 / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D009419:Nerve Tissue Proteins / Q000187:drug effects / Q000378:metabolism; D011687:Purines / Q000494:pharmacology*; D000077546:Roscovitine
chemical_list: D000970:Antineoplastic Agents; D009419:Nerve Tissue Proteins; D011687:Purines; C089495:neuronal Cdk5 activator (p25-p35); D000077546:Roscovitine; D051360:Cyclin-Dependent Kinase 5