Cytotoxic properties of titanocenyl amides on breast cancer cell line mcf-7

Interaction of metallocene dichlorides with apo-human transferrin: A spectroscopic study and cytotoxic activity against human cancer cell lines

Metallocene dichlorides (Cp₂M(IV)Cl₂) are the first class of small and hydrophobic organometallic compounds classified as anticancer agents against numerous cancer cell lines and tumors. In this study, the antiproliferative activities of Cp₂VCl₂,Cp₂NbCl₂, Cp₂HfCl₂ and Cp₂ZrCl₂were assessed on two human cancer cell lines (HT-29 and MCF-7) using MTT assay. Spectroscopic studies were also conducted using these and other known metallocene dichlorides on apo-human transferrin (apo-hTf) at pH 7.4. UV-Vis and CD showed that their interaction with apo-hTf could induce conformational changes of its secondary structure during binding process. In fluorescence, a decrease in intensity of the emission peak was observed when the apo-hTf:Cp₂M(IV)Cl₂ complex is being formed, probably due to changes in the microenvironment of its tyrosine and tryptophan residues. Among all metallocene dichlorides studied, Cp₂VCl₂ has the strong ability to quench the intrinsic fluorescence of apo-hTf through a static quenching mechanism. The association constants for each protein-compound complex were also determined at different temperatures (296 K, 303 K, 310 K, and 317 K) based on fluorescence quenching results. Positive enthalpy changes (ΔH) and entropy changes (ΔS) as well as negative free energies (ΔG) suggest that hydrophobic interactions are the main intermolecular forces involved in the binding process, probably via an endothermic and spontaneous reaction mechanism. The distance, r, between donor (apo-hTf) and acceptor (Cp₂M(IV)Cl₂) obtained according to Forster's theory of non-radiation energy transfer suggest that the energy transfer from apo-hTf to Cp₂M(IV)Cl₂ occurs with high probability and distances obtained by FRET with high accuracy.

Anti-cancer applications of titanocene-functionalised nanostructured systems: an insight into cell death mechanisms

A series of alkenyl-substituted titanocene compounds have been supported on the mesoporous silica-based material KIT-6. The corresponding functionalised materials were completely characterised by different techniques (solid-state multinuclear NMR spectroscopy, IR spectroscopy, N2 adsorption-desorption isotherms, X-ray fluorescence and diffraction, SEM and TEM) to observe the incorporation of the titanocene derivatives on the external surface of the material KIT-6. Both the titanocene compounds and the materials were tested in vitro against a wide variety of human cancer and normal cell lines. A very high cytotoxicity of the synthesised titanocene derivatives (IC50 values in the range of those described in the literature for the most active cytotoxic titanocene compounds), with selectivity towards cancer cell lines was observed. The cytotoxic activity of the materials is the highest reported to date for titanocene-functionalised materials. In addition, higher Ti uptake (from 4 to 23% of the initial amount of Ti) of the cells treated with materials was observed with respect to those treated with "free" titanocene derivatives (which gave Ti uptake values from 0.4 to 4.6% of the initial amount of Ti). Additional experiments with the titanocene derivatives and the functionalised materials revealed that changes to the morphological and functional dynamics of apoptosis occurred when the active titanocene species were incorporated into mesoporous materials. In addition, the materials could induce programmed cell death in tumour cell populations by impairing the damaged DNA repair mechanisms and by upregulation of intrinsic and extrinsic apoptotic signalling pathways.

The addition of a pregnenolone pendant group enhances the anticancer properties of titanocene dichloride in a mcf-7 xenograft model

BACKGROUND/AIM

Titanocene dichloride held great promise as a chemotherapeutic compound in pre-clinical studies. However, subsequent clinical trials revealed hepatoxicity and nephrotoxicity, which limited its use in clinical applications. Therefore, we used steroid pendant groups to improve the targeting of titanocene in MCF-7 breast cancer cells, and demonstrated a 10-fold lower effective dose compared to titanocene in in vitro assays. The aim of the present study was to test the efficacy of a titanocene functionalized with pregnenolone (Ti-Preg) in an in vivo breast cancer model.

MATERIALS AND METHODS

Xenografts from the MCF7 breast cancer cell line were implanted into athymic nu/nu mice to evaluate the potential of Ti-Preg as an anti-breast cancer agent.

RESULTS

Ti-Preg demonstrated significant inhibition of MCF-7 tumor growth when compared to vehicle and to titanocene controls.

CONCLUSION

Our findings demonstrate the potential of steroid pendent groups for targeting chemotherapeutics to steroid hormone-dependent cancer.

Synthesis, spectral characterization, and antiproliferative studies of mixed ligand titanium complexes of adamantylamine

Titanium complexes have been synthesized by the reaction between titanium tetrachloride (TiCl4), respective bidentate ligand [4,4' -dimethoxy-2,2' -bipyridine (bpome), 6,6'-dimethyl-2,2'-bipyridine (dpme), 1,2-diaminocyclohexane (dach), 1,10-phenanthroline (phen), and benzoylacetone (bzac)], and adamantylamine (ada) in 1 : 2 : 2 molar ratios, respectively. The structure of synthesized complexes was confirmed using elemental analysis, FTIR, UV-visible, (1)H NMR, and mass spectrometry techniques. The nanocrystalline nature of complexes was confirmed by powder XRD study. The complexes were evaluated for cytotoxic potential in HeLa (cervical), C6 (glioma), and CHO (Chinese hamster ovarian) cell lines. The complex E was found to be more effective cytotoxic agent against HeLa cell line with an IC50 value of 4.06 µM. Furthermore, the effect of synthesized complexes was studied on different stages of the cell cycle in CHO cells. All complexes exhibited the dose dependent increase in cytotoxicity. The results have shown an increase in sub-G0 population with increase in concentration which is an indicative measure of apoptosis.

Host-Guest Interactions between Calixarenes and Cp(2)NbCl(2)

The possible inclusion complexes of Cp(2)NbCl(2) into calixarenes hosts have been investigated. The existence of a true inclusion complex in the solid state was confirmed by a combination of NMR, ab-initio calculations, thermogravimetric analysis, FTIR, Raman and PXRD. Ab-initio calculations, (1)H NMR solution and solid state (13)C CP MAS NMR results demonstrated that p-sulfonic calix[6]arene does form an inclusion complex with Cp(2)NbCl(2). Raman spectroscopy showed, for the inclusion compound of p-sulfonic calix[6]arene-Cp(2)NbCl(2), a band between 500-850 cm(-1) characteristic of Nb-O vibration. This result suggests that Nb(V) may engage in coordination with the oxygen of the sulfonate group, as part of the host-guest interaction. However, it is important to mention that the niobocene dichloride (Cp(2)NbCl(2)) dissolves in water and undergoes oxidation and hydrolysis processes to yield Cp(2)NbCl(2)(OH) species. For that reason this band does not exclude that the Nb-O band belongs to Cp(2)NbCl(2)(OH). Solid State (13)C CP MAS NMR and solution (1)H NMR spectroscopies together with ab-initio results showed that Cp(2)NbCl(2) is included in the p-sulfonic calix[6]arene cavity, with both Cp rings inside the cavity. In contrast, the solution (1)H NMR results demonstrated that calix[6]arene does not form inclusion complex with Cp(2)NbCl(2) in CDCl(3) solution. Cp(2)NbCl(2) is not included in the calix[6]arene cavity, possibly due to the lack of sulfonate heads which promote Nb-O interactions and assist the inclusion of Cp(2)NbCl(2) into the cavity.

Synthesis, characterization and cytotoxic studies of water soluble [(η-C(5)H(5))(2)Mo(thionucleobase/thionucleoside)]Cl complexes in breast and colon cancer cell lines

Four new water soluble molybdenocene complexes were synthesized in aqueous solution at pH 7.0. The new species, [(η(5)-C(5)H(5))(2)Mo(L)]Cl (L= 6-mercaptopurine, 2-amino-6-mercaptopurine, (-)-2-amino-6-mercaptopurine ribose and 6-mercaptopurine ribose), were characterized by spectroscopic methods. NMR spectroscopic data showed the presence of two coordination isomers, S(6), N(7) and S(6), N(1), in aqueous solution, being S(6), N(7) the most stable. The antiproliferative activities of the new species were investigated in HT-29 colon and MCF-7 breast cancer cell lines. The incorporation of molybdenocene (Cp(2)Mo(2+)) into the thionucleobases/thionucleosides decreases their cytotoxic activities in HT-29 colon cancer cell line. In contrast, in the MCF-7 cell line, [Cp(2)Mo(2-amino-6-mercaptopurine)]Cl showed a high cytotoxic activity. This is most likely a consequence of the enhanced lipophilic character on the thionucleobase combined with synergism between Cp(2)Mo(2+) and the thionucleobase ligand.