Elsevier

European Journal of Pharmacology

Volume 760, 5 August 2015, Pages 136-144
European Journal of Pharmacology

Molecular and cellular pharmacology
Improved in vitro antitumor potential of (O,O′-Diisobutyl-ethylenediamine-N,N′-di-3-propionate)tetrachloridoplatinum(IV) complex under normoxic and hypoxic conditions

https://doi.org/10.1016/j.ejphar.2015.04.012Get rights and content

Abstract

(O,O′-Diisobutyl-ethylenediamine-N,N′-di-3-propionate)tetrachloridoplatinum(IV), [PtCl4(iBu2eddp)], shows an improved pharmacological profile in comparison to cisplatin. This is manifested through accelerated dying process led by necrotic cell death, reflected through mitochondrial collapse, strong ATP depletion and reactive oxygen species production. Loss of mitochondrial potential was further followed with intensive apoptosis that finalized with DNA fragmentation.

Different dynamic of tumoricidal action could be partly ascribed to less affected repair mechanisms in comparison to cisplatin. Importantly, [PtCl4(iBu2eddp)] did not induce necrosis in primary fibroblasts suggesting different intracellular response of normal vs. tumor cells. This selectivity toward malignant phenotype is further confirmed by retained tumoricidal potential in hypoxic conditions, while cisplatin became completely inefficient.

Introduction

One of the major causes of death in humans is cancer. Cisplatin, cis-[PtCl2(NH3)2], (Fig. 1A) is one of the most successful anticancer compounds in treatment of various types of tumors (Harrap, 1985, Kalinowska-Lis et al., 2008, Kidani et al., 1978, Knox et al., 1986, Lippert, 1999, Siddik, 2003, Rosenberg et al., 1965, Wong and Giandomenico, 1999). Since the discovery of its activity, unfortunately accompanied by serious side effects (e.g. nephrotoxicity, emetogenicity and neurotoxicity) synthesis of new platinum-based compounds that would be less toxic to healthy tissue gained a progressively increasing interest (Allardyce et al., 2005, Dyson and Sava, 2006, Garbutcheon-Singh et al., 2011, Gómez-Ruiz et al., 2012, Orvig and Abrams, 1999, Rau and van Eldik, 1996). About 20 million cancer cases are expected to occur in the next two decades, which renders the quest for new and improved antineoplastic agents.

This is an urgent issue in the field of Biomedicine and Human Health. Besides cisplatin, only carboplatin and oxaliplatin are in worldwide clinical use (Kelland, 2007). Particularly in the treatment of cancer, inorganic compounds have had an enormous impact, their activity relying mostly on specific interactions with DNA, leading to damage and ultimately to cell death (Dyson and Sava, 2006, Farrell, 1999, Farrell, 2004, Fricker, 2007, Gielen, 1988, Hannon, 2007, Van Rijt and Sadler, 2009).

There is a growing interest in platinum(IV) compounds as they have increased inertness relative to platinum(II) complexes. This property allows oral administration and reduced toxicity (Choy, 2006, Galanski et al., 2003, Hall and Hambley, 2002, Kelland, 2007, Zhang and Lippard, 2003). Satraplatin, as a platinum(IV) complex that has overcome Phase III clinical trials, showed great efficiency against several platinum-resistant human cancer cell lines (Choy et al., 2008, Fokkema et al., 2002, Samimi and Howell, 2006), including lung, ovary, cervix, and prostate (pivotal SPARC trial, Satraplatin and Prednisone Against Refractory Cancer) (Sonpavde and Sternberg, 2009, Sternberg et al., 2009). Proper choice of ligands is crucial for anticancer activity of metallodrugs, and it should be following structure–activity relationships. These organic molecules can modify lipophilicity or stabilize specific oxidation states of metal ions, as well as control reactivity (Arnesano and Natile, 2009).

Platinum(IV) complexes with R2edda-type ligands (dialkyl esters of ethylenediamine-N,N′-diacetic acid and its derivatives), are considered to be variants of satraplatin with κ2N,N′ mode of coordination (Kaluđerović et al., 2008b). Such compounds, obtained by structural variations of the aminocarboxylato arms and alkyl groups of the ester moiety (normal, branched chains, rings), yielded a large group of R2edda-type platinum complexes (Kaluđerović et al., 2008a, Kaluđerović et al., 2009, Krajčinović et al., 2008, Lazić et al., 2010, Vujić et al., 2011, Zmejkovski et al., 2009). The most efficient complexes were found to be tetrachloridoplatinum(IV) complexes with nBu and nPe esters of ethylenediamine-N,N′-di-3-propionic acid, [PtCl4(nBu2eddp)] and [PtCl4(nPe2eddp)] (Fig. 1B) against human adenocarcinoma HeLa cells (approx. five times less active than cisplatin) and human myelogenous leukemia K562 cells (comparable with cisplatin) acting through apoptotic cell death (Kaluđerović et al., 2005a). Noteworthy in vitro activity caused by these two platinum(IV) complexes was demonstrated on L929 fibrosarcoma and U251 astrocytoma tumor cells (Kaluđerović et al., 2005b, Mijatović et al., 2005). The compounds are found to induce considerably faster tumor cell death process than cisplatin (Kaluđerović et al., 2005b).

Recently, [PtCl4(iBu2eddp)] (Fig. 1C) was tested, among related compounds, against various cell lines: CT26CL25, HTC116, SW620, PC3, LNCaP, U251, A375, B16 and two normal primary cells (fibroblasts and keratinocytes) (Kaluđerović et al., 2012). On the representative HCT116 cell line, human colon cancer, mechanism of action was studied and it was found that it is less toxic to normal primary cells but induced caspase dependent apoptosis of HCT116 followed with autophagic cell death. Furthermore, reactive oxygen species and reactive nitrogen species are not the major mediators of drugs toxicity (Kaluđerović et al., 2012). In this work we report that [PtCl4(iBu2eddp)] complex showed qualitatively improved in vitro antitumor potential in comparison to cisplatin under normoxic and hypoxic conditions.

Section snippets

Synthesis of [PtCl4(iBu2eddp)]

The platinum(IV) complex, [PtCl4(iBu2eddp)], was synthesized as described in literature (Kaluđerović et al., 2012) and structure was confirmed with 1H and 13C NMR spectroscopy.

Reagents

Fetal calf serum (FCS), RPMI-1640, phosphate-buffered saline (PBS), and propidium iodide (PI) were obtained from Sigma (St. Louis, MO). Annexin V-FITC (AnnV) was from Biotium (Hayward, CA). Apostat was purchased from R&D (R&D Systems, Minneapolis, MN USA). Hypoxic bags (Microbiology Anaerocult A mini) were bought from

[PtCl4(iBu2eddp)] decreases cell viability more potently than cisplatin

L929 cells were exposed to a wide range of doses of cisplatin or [PtCl4(iBu2eddp)]. After 24 h of cultivation, both compounds remarkably decreased the number of viable cells (Fig. 2A). IC50 results revealed significant difference in effective concentration of tested compounds (IC50=27 µM, cisplatin; 16 µM, [PtCl4(iBu2eddp)]). Time dependent evaluation of the cell viability of cultures exposed to IC50 doses of platinum(IV) and platinum(II) complexes revealed difference already visible after only 2 h

Discussion

The in vitro antitumor activity of [PtCl4(iBu2eddp)] was investigated against mouse fibrosarcoma L929 cell line. The results showed dose-dependent action of tested platinum complex and higher efficiency in comparison to cisplatin against investigated cells (Fig. 2A). Concordantly with our previous data (Kaluđerović et al., 2012), it is obvious that [PtCl4(iBu2eddp)] complex possesses more potent capacity to down-regulate tumor cell growth than cisplatin. These two structurally different

Conclusion

In the current study, detailed analysis of [PtCl4(iBu2eddp)] antitumor action against fibrosarcoma L929 cell line was conducted and the following conclusions can be drawn:

  • 1.

    Platinum(IV) compound revealed improved anticancer profile in comparison to cisplatin.

  • 2.

    [PtCl4(iBu2eddp)] induced necrotic cell death accompanied with strong apoptotic process.

  • 3.

    This dual potential makes it selective toward cancer cells.

  • 4.

    [PtCl4(iBu2eddp)] induces less DNA damage and its toxicity is more related to ATP depletion,

Acknowledgments

The authors would like to acknowledge financial support from the Ministry of Science and Technological Development of the Republic of Serbia (Project nos. 173013, 173020 and 172035), SMWK (Project no. 33707045), SAB (ESF, Project no. 100147954) and the Free State of Saxony (Project no. 100099597) and Dr. Djordje Miljković for the help in flow cytometry analysis.

References (61)

  • S. Mijatović et al.

    Study of the anticancer properties of methyl- and phenyl-substituted carbon- and silicon-bridged ansa-titanocene complexes

    J. Organomet. Chem.

    (2014)
  • P. Nicotera et al.

    Intracellular ATP, a switch in the decision between apoptosis and necrosis

    Toxicol. Lett.

    (1998)
  • S.H. Van Rijt et al.

    Current applications and future potential for bioinorganic chemistry in the development of anticancer drugs

    Drug Discov. Today

    (2009)
  • J.M. Vujić et al.

    Stereospecific ligands and their complexes. Part VII. Synthesis, characterization and in vitro antitumoral activity of platinum(II) complexes with O,O′-dialkyl esters of (S,S)-ethylenediamine-N,N′-di-2-(4-methyl)pentanoic acid

    Eur. J. Med. Chem.

    (2011)
  • C.X. Zhang et al.

    New metal complexes as potential therapeutics

    Curr. Opin. Chem. Biol.

    (2003)
  • B.B. Zmejkovski et al.

    Palladium(II) complexes with R2edda-derived ligands. Part II. Synthesis, characterization and in vitro antitumoral studies of R2eddip esters and palladium(II) complexes

    Eur. J. Med. Chem.

    (2009)
  • C.S. Allardyce et al.

    Development of organometallic (organo-transition metal) pharmaceuticals

    Appl. Organomet. Chem.

    (2005)
  • P. Bernardi et al.

    Mitochondria and cell death. Mechanistic aspects and methodological issues

    Eur. J. Biochem.

    (1999)
  • M. Boland et al.

    Mitochondrial dysfunction in cancer

    Front. Oncol.

    (2013)
  • R. Brem et al.

    XRCC1 is required for DNA single-strand break repair in human cells

    Nucleic Acids Res.

    (2005)
  • J.R. Cantor et al.

    Cancer cell metabolism: one hallmark, many faces

    Cancer Discov.

    (2012)
  • H. Choy

    Satraplatin: an orally available platinum analog for the treatment of cancer

    Expert Rev. Anticancer Ther.

    (2006)
  • H. Choy et al.

    Current status and future prospects for satraplatin, an oral platinum analogue

    Clin. Cancer Res.

    (2008)
  • M. Crompton

    The mitochondrial permeability transition pore and its role in cell death

    Biochem. J.

    (1999)
  • P.J. Dyson et al.

    Metal-based antitumour drugs in the post genomic era

    Dalton Trans.

    (2006)
  • M. Fallahi-Sichani et al.

    Metrics other than potency reveal systematic variation in responses to cancer drugs

    Nat. Chem. Biol.

    (2013)
  • N. Farrell

    Uses of Inorganic Chemistry in Medicine

    (1999)
  • N. Farrell

    Polynuclear platinum drugs

  • S.P. Fricker

    Metal based drugs: from serendipity to design

    Dalton Trans.

    (2007)
  • M. Galanski et al.

    Recent developments in the field of tumor-inhibiting metal complexes

    Curr. Pharm. Des.

    (2003)
  • Cited by (7)

    • Palladium(II) complexes: Structure, development and cytotoxicity from cisplatin analogues to chelating ligands with N stereocenters

      2022, Inorganica Chimica Acta
      Citation Excerpt :

      Some structure activity relationships were concluded for (S,S)-R2eddip and (S,S)-R2eddl esters and their complexes: the order of activity is related to the R substituent, namely on raising the lipophilicity of the ester groups the cytotoxic activity increases in both, esters and in the palladium complexes, with some exceptions. Nevertheless, by replacing of the central metal ion from palladium(II) to platinum(II/IV), cytotoxic action increases significantly [92,94,105,106,120], thus, mechanism of action is investigated in more detail fore chosen platinum complexes [103,121]. Beside these, also some Ru(II) complexes with R2edda-type ligands were prepared and in vitro tested [122].

    • Antitumor potential of cisplatin loaded into SBA-15 mesoporous silica nanoparticles against B16F1 melanoma cells: in vitro and in vivo studies

      2021, Journal of Inorganic Biochemistry
      Citation Excerpt :

      For viability assays 5000 cells/well in 96 well plate was used, while for flow cytometry measurements 2.5 × 105 cells/well in 6 well plate was used. The viability of the cells was measured by CV (crystal violet) and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays as described previously [48]. Absorbance was measured using a 96-well plate reader (Tecan Spectra, Crailsheim, Germany).

    • Cancer cell specific cytotoxic effect of Rhoeo discolor extracts and solvent fractions

      2016, Journal of Ethnopharmacology
      Citation Excerpt :

      In contrast, the cell line Hep-G2 exhibited a higher susceptibility with the fractions involving non-polar extraction methods, including Petroleum Ether and Chloroform extract fractions, which suggest that molecules found in small quantities could be specifically bioactive against this cell line. As a basis for comparison of the activity of the R. discolor extracts with a known chemotherapeutic agent, it has been reported that when exposed to 10 μg/ml of cisplatin HT-29 population was reduced to 58.8% of viable cells (Santos-Zea et al., 2016); Hep-G2 was reduced to 40% of viable cells (Liu et al., 2014); PC-3 only showed a 6.8% population reduction (Li et al., 2010); while NIH 3T3 was not affected by the exposure (Bulatovi,ć et al., 2015). Phenolic compounds have been described as powerful antioxidants given their ability to scavenge free radicals and thereby preventing oxidation of cell molecules (Petrovic et al., 2015).

    View all citing articles on Scopus
    View full text