Keywords: apoptosis, cordycepin, cytochrome c, Cdc25A, DNA damage, p53, S-phase arrest Abbreviations: ATM, Ataxia telangiectasia mutated; ATR, ATM and Rad3-related; PI, Propidium iodide; PFT-a, Pifithrin-a; XIAP, X-linked inhibitor of apoptosis protein.Cordycepin, an adenosine analog derived from Cordyceps militaris has been shown to exert anti-tumor activity in many ways. However, the mechanisms by which cordycepin contributes to the anti-tumor still obscure. Here our present work showed that cordycepin inhibits cell growth in NB-4 and U937 cells by inducing apoptosis. Further study showed that cordycepin increases the expression of p53 which promotes the release of cytochrome c from mitochondria to the cytosol. The released cytochrome c can then activate caspase-9 and trigger intrinsic apoptosis. Cordycepin also blocks MAPK pathway by inhibiting the phosphorylation of ERK1/2, and thus sensitizes the apoptosis. In addition, our results showed that cordycepin inhibits the expression of cyclin A2, cyclin E, and CDK2, which leads to the accumulation of cells in S-phase. Moreover, our study showed that cordycepin induces DNA damage and causes degradation of Cdc25A, suggesting that cordycepin-induced S-phase arrest involves activation of Chk2-Cdc25A pathway. In conclusion, cordycepin-induced DNA damage initiates cell cycle arrest and apoptosis which leads to the growth inhibition of NB-4 and U937 cells.
The enediyne antitumor antibiotic maduropeptin (MDP) is produced by Actinomadura madurae ATCC 39144. The biosynthetic pathway for the 3,6-dimethylsalicylic acid moiety of the MDP chromophore is proposed to be comprised of four enzymes: MdpB, MdpB1, MdpB2, and MdpB3. Based on the previously characterized biosynthesis of the naphthoic acid moiety of neocarzinostatin (NCS), we expected a biosynthetic pathway featuring carboxylic acid activation by the MdpB2 CoA ligase immediately before its coupling to an enediyne core intermediate. Surprisingly, the MDP aromatic acid biosynthetic pathway employs an unusual logic in which MdpB2-catalyzed CoA activation occurs before MdpB1-catalyzed C-methylation, demonstrating that MdpB1 is apparently unique in its ability to C-methylate a CoA-tethered aromatic acid. MdpB2 is a promiscuous CoA ligase capable of activating a variety of salicylic acid analogues, a property that could be potentially exploited to engineer MDP analogues.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.