A novel Cu(II)–mal–picoline complex induces mitotic catastrophe mediated by deacetylation of histones and a-tubulin leading to apoptosis in human cell lines Biswarup Saha,† a Ananda Mukherjee,† a Saheli Samanta,† a Susmita Paul,† a Debalina Bhattacharya,† a Chitta Ranjan Santra† b and Parimal Karmakar† * a Received 14th November 2011, Accepted 2nd June 2012 DOI: 10.1039/c2md00285j In this study, we investigated mitotic catastrophe followed by apoptosis induced in human cell lines [HeLa, HepG2 and THP1] by a novel Cu(II) complex having malonate as the primary ligand and protonated 2-amino-4-picoline as the counter ion; whose in vitro DNA binding ability was demonstrated previously (B. Saha et al., J. Phys. Chem. B, 2010, 114(17), 5851–5861). Using the auto- fluorescence property of the complex, it was observed that the complex entered into the cells within 15 min after the exposure and was able to kill cells as determined by clonogenic survivability and MTT assay in a dose and time dependent manner. While dissecting the cell killing mechanisms, it was found that initially the complex induced multinucleated cells by inhibiting acetylation of a histone acetyl transferase (HAT) domain of CBP/p300, although histone deacetylase 6 (HDAC6) expression did not change much. As a result, histone proteins, H3 and H2AX, along with a non-histone protein, a-tubulin, were mostly deacetylated after 48 h of the treatment. This eventually led to mitotic catastrophe (MC), as histone acetylation–deacetylation dynamics is essential for the successful mitosis. DNA damage- induced gH2AX and 53BP1 foci in the treated cells were also observed after 72 h of treatment, as abnormal mitosis with decondensed chromosomes are prone to nucleolytic attack. These molecular phenomena ultimately rendered apoptosis. Taken together, our results provided evidence that the said complex perturbed the signaling events associated with mitosis and consequently induced cell death. 1. Introduction The transition element copper is vital for the healthy functioning of higher organisms including respiration, angiogenesis, and immune response. 2–4 Recently, medical research has focused on copper complexes for the development of different therapeutic agents including cancer. 5,6 The rationale for using copper complexes as anti-cancer agents is to avoid severe side effects induced by known anticancer agents like bleomycin, cis-platin, etoposide, etc. 7–11 Copper modulation has been suggested to be a potential modality in therapy for several diseases. The ability to cycle between +1 and +2 oxidation states of copper is one of the main features that has been exploited in biological systems. 12–14 Depending on the nature of the complex associated with copper, diverse cellular response has been elucidated. Perturbation in distinct mode of cell survival signal or induction of specific pathways associated with cell dismissal has been shown to induce by the copper-complex in vitro. 15–19 Many copper complexes are demonstrated for their anticancer activity, which is mainly mediated through the induction of oxidative stress. 20–22 N-Sali- cylidene-L-glutamato diaqua copper(II) complex (CuC) was shown to induce cell death via production of ROS in mice leukemia cells L1210. 23 Recently, copper N-(2-hydrox- yacetophenone)glycinate (CuNG) has been reported to increase the ROS level in the liver of doxorubicin-resistant Ehrlich ascites carcinoma (EAC/Dox) bearing swiss albino mice and can modulate different anti-oxidant enzymes. 24 Another copper(II) complex of ethyl 2-[bis(2-pyridylmethyl)amino]propionate ligand (ETDPA) has shown to be effective in killing HeLa cells via the ROS-triggered autophagic pathway. 25 Similarly, copper– dopamine complex induces mitochondrial autophagy in the cultured cells prior to caspase independent apoptotic death. 26 Several organic ligands have been found to complex with copper spontaneously or can be made to complex with copper easily. For example, it has been reported that 8-hydroxylquinoline (8- OHQ) is able to form a copper complex that inhibits proteasome and induces apoptosis in cancer cells. 27 Similarly, glutamine Schiff base complexed with copper has been reported to selec- tively inhibit the proteasomal activity and induce cell death in a Department of Life Science and Biotechnology, Jadavpur University, 188, Raja S.C. Mullick Road, Kolkata-700 032, West Bengal, India. E-mail: pkarmakar_28@yahoo.co.in; karmakarparimal@gmail.com; Fax: +91 33 2413 7121; Tel: +91 33 2414 6710 b Department of Chemistry, Netaji Nagar Day College, NSC Bose Road, Regent Estate, Kolkata-700 092, West Bengal, India † PK conceived and designed the experiments; BS, AM, SS, SP and DB performed the experiments; PK, BS, AM and CRS analyzed the data; PK contributed reagents/materials/analysis tools; PK and BS wrote the paper. This journal is ª The Royal Society of Chemistry 2012 Med. Chem. Commun. Dynamic Article Links C < MedChemComm Cite this: DOI: 10.1039/c2md00285j www.rsc.org/medchemcomm CONCISE ARTICLE Downloaded by University of Rhode Island on 16 July 2012 Published on 18 June 2012 on http://pubs.rsc.org | doi:10.1039/C2MD00285J View Online / Journal Homepage