Roscovitine and purvalanol are specific cyclin-dependent kinase (CDK) inhibitors, which induce apoptosis by triggering cell cycle arrest in various cancer cells such as colon, prostate, and breast cancer cells. Although the apoptotic action of roscovitine was clarified at the molecular level, the exact mechanism of purvalanol-induced apoptosis is still under investigation. | Turkish Journal of Biology Research Article Turk J Biol (2014) 38: 867-879 © TÜBİTAK doi: Downregulation of c-Myc mediated ODC expression after purvalanol treatment is under control of upstream MAPK signaling axis in MCF-7 breast cancer cells Pınar OBAKAN, Gizem ALKURT*, Betsi KÖSE*, Ajda ÇOKER GÜRKAN, Elif Damla ARISAN**, Deniz COŞKUN, Zeynep Narçin ÜNSAL Department of Molecular Biology and Genetics, Faculty of Science and Letters, İstanbul Kültür University, Ataköy Campus, İstanbul, Turkey Received: Accepted: Published Online: Printed: Abstract: Roscovitine and purvalanol are specific cyclin-dependent kinase (CDK) inhibitors, which induce apoptosis by triggering cell cycle arrest in various cancer cells such as colon, prostate, and breast cancer cells. Although the apoptotic action of roscovitine was clarified at the molecular level, the exact mechanism of purvalanol-induced apoptosis is still under investigation. The mitogenactivated protein kinase (MAPK) signaling cascade is activated by different inducers related to growth, proliferation, differentiation processes, or environmental stress factors. Recent reports showed that modulation of MAPKs might lead to regulation of c-Myc, which is a transcription factor for the polyamine (PA) biosynthesis enzyme, ornithine decarboxylase (ODC). PAs are amine-derived cationic molecules that play crucial roles in cell proliferation, growth, and differentiation. In this study, we investigated the potential role of the MAPK signaling cascade in the purvalanol-induced apoptosis mechanism by comparing the results of roscovitine in MCF7 and MDA-MB-231 breast cancer cells. We found that CDK inhibitors decreased the cell viability in a dose- and time-dependent manner in MCF-7 and MDA-MB-231 cancer cells. Although both CDK inhibitors induced cell cycle arrest, which led to apoptosis by activating caspases and PARP cleavage
