Synthesis, structural characterisation and biological studies of new mononuclear platinum(II) complexes with sterically hindered heterocyclic ligands

Three novel cisplatin analogues were synthesized, designed according to an approach which violates the ‘‘classical’’ structure–activity relationship, by replacing the diamine ligands with a planar N donor heterocycle giving a sterically hindered complex. Moreover, the sterical hindrance of antitumor drug candidates potentially makes them less susceptible to deactivation by sulphur-containing proteins and helping to overcome resistance mechanisms. The resulting mononuclear complexes of sterically hindered polidentate heterocyclic N ligands [PtCl(bbp)]Cl (1) [bbp = 2,6-bis(2-benzimidazolyl)pyridine], [PtCl2(dptdn)](H2O) (2) [dptdn = sodium 5,6-diphenyl-3-(20-pyridyl)-1,2,4-triazine-400,400 0-disulfonate] and [(dptdn)(dpt)Pt]Cl2(H2O) (3) [dpt = 5,6-diphenyl-3-(20-pyridyl)-1,2,4-triazine] have been prepared and structurally characterised. Both neutral and ionic complexes are present, with monofunctional (1) and bifunctional Pt(II) moieties (2) and coordinatively saturated Pt(II) ions in the mixed ligand complex (3), whose size and shape enable them to behave as novel scaffolds for DNA binding. All complexes were tested ‘‘in vitro’’ for their biological activity on human HT29 colorectal carcinoma and HepG2 hepatoma cells. The complexes (1) and (3), endowed with a positive charge, showed a potent cytotoxic activity and reduced cell viability with an efficacy higher than that of cisplatin; whilst the neutral bifunctional compound (2) was inactive. IC50 values have been calculated for the active compounds. The cytotoxic effects were confirmed by the accumulation of treated cells in subG0/G1 phase of cell cycle, by the loss of mitochondrial potential (Dwm) and by the chromatin condensation or fragmentation observed by means of fluorescence microscopy after Hoechst 33258 nuclear staining. A study on intracellular platinum uptake in HT29 cell line has been also performed and data obtained strongly suggest that the cytotoxicity of new tested complexes reported in this work is based on a different pharmacodynamic pattern with respect to cisplatin

DNA microarray profiling of genes differentially regulated by the histone deacetylase inhibitors vorinostat and LBH589 in colon cancer cell lines

<p>Abstract</p> <p>Background</p> <p>Despite the significant progress made in colon cancer chemotherapy, advanced disease remains largely incurable and novel efficacious chemotherapies are urgently needed. Histone deacetylase inhibitors (HDACi) represent a novel class of agents which have demonstrated promising preclinical activity and are undergoing clinical evaluation in colon cancer. The goal of this study was to identify genes in colon cancer cells that are differentially regulated by two clinically advanced hydroxamic acid HDACi, vorinostat and LBH589 to provide rationale for novel drug combination partners and identify a core set of HDACi-regulated genes.</p> <p>Methods</p> <p>HCT116 and HT29 colon cancer cells were treated with LBH589 or vorinostat and growth inhibition, acetylation status and apoptosis were analyzed in response to treatment using MTS, Western blotting and flow cytometric analyses. In addition, gene expression was analyzed using the Illumina Human-6 V2 BeadChip array and Ingenuity^®Pathway Analysis.</p> <p>Results</p> <p>Treatment with either vorinostat or LBH589 rapidly induced histone acetylation, cell cycle arrest and inhibited the growth of both HCT116 and HT29 cells. Bioinformatic analysis of the microarray profiling revealed significant similarity in the genes altered in expression following treatment with the two HDACi tested within each cell line. However, analysis of genes that were altered in expression in the HCT116 and HT29 cells revealed cell-line-specific responses to HDACi treatment. In addition a core cassette of 11 genes modulated by both vorinostat and LBH589 were identified in both colon cancer cell lines analyzed.</p> <p>Conclusion</p> <p>This study identified HDACi-induced alterations in critical genes involved in nucleotide metabolism, angiogenesis, mitosis and cell survival which may represent potential intervention points for novel therapeutic combinations in colon cancer. This information will assist in the identification of novel pathways and targets that are modulated by HDACi, providing much-needed information on HDACi mechanism of action and providing rationale for novel drug combination partners. We identified a core signature of 11 genes which were modulated by both vorinostat and LBH589 in a similar manner in both cell lines. These core genes will assist in the development and validation of a common gene set which may represent a molecular signature of HDAC inhibition in colon cancer.</p

Crosstalk between reactive oxygen species and pro-inflammatory markers in developing various chronic diseases: a review

The inflammation process in the human body plays a central role in the pathogenesis of many chronic diseases. In addition, reactive oxygen species (ROS) exert potentially a decisive role in human body, particularly in physiological and pathological process. The chronic inflammation state could generate several types of diseases such as cancer, atherosclerosis, diabetes mellitus and arthritis, especially if it is concomitant with high levels of pro-inflammatory markers and ROS. The respiratory burst of inflammatory cells during inflammation increases the production and accumulation of ROS. However, ROS regulate various types of kinases and transcription factors such nuclear factor-kappa B which is related to the activation of pro-inflammatory genes. The exact crosstalk between pro-inflammatory markers and ROS in terms of pathogenesis and development of serious diseases is still ambitious. Many studies have been attempting to determine the mechanistic mutual relationship between ROS and pro-inflammatory markers. Therefore hereby, we review the hypothetical relationship between ROS and pro-inflammatory markers in which they have been proposed to initiate cancer, atherosclerosis, diabetes mellitus and arthritis

Sintesi, caratterizzazione e studio dell'attivit\ue0 biologica di nuovi complessi mononucleari di PT(II) con leganti eterociclici

Sono stati precedentemente sintetizzati complessi mono- e polinucleari di Pt(II) [1, 2] che hanno mostrato attivit\ue0 citotossica maggiore del cisplatino. Tre nuovi complessi mononucleari di Pt(II) analoghi del cisplatino sono stati quindi in seguito preparati usando leganti eterociclici quali: 5,6-difenil-3-(2-piridil)-1,2,4-triazina-4\u2019,4\u2019\u2019-disulfonato sodico (dptdn), 5,6-difenil-3-(2-piridil)-1,2,4-triazina (dpt) e 2,6-bis(2-benzimidazolil)piridina (bbp). I risultanti tre complessi [PtCl(bbp)]Cl (1), [PtCl2(dptdn)](H2O) (2) e [(dptdn)(dpt)Pt]Cl2(H2O) (3), ionici (1) e (3) e neutro (2), sono stati sintetizzati e strutturalmente caratterizzati tramite spettroscopia IR e NMR 1D e 2D 1H e 13C. La coordinazione dello ione Pt(II) in (1) \ue8 effettuata da tre atomi di azoto dando origine a un complesso ionico altamente simmetrico. Il complesso asimmetrico (2) contiene una met\ue0 bifunzionale PtCl2, legata a due atomi di azoto del legante eterociclico con coordinazione analoga al cisplatino. Il complesso ionico (3) contiene due differenti leganti eterociclici azotati che danno origine a un complesso planare che contiene lo ione Pt(II) coordinato da quattro atomi di azoto. L\u2019attivit\ue0 citotossica di questi complessi del Pt(II), aventi una struttura \u201cnon classica\u201d, \ue8 stata studiata mediante il saggio di vitalit\ue0 MTT su due diverse linee di tumore umano in coltura: cellule di epatocarcinoma HepG2 e cellule di carcinoma colorettale HT29. Entrambe le linee cellulari mostrano una chiara riduzione della loro vitalit\ue0 dopo trattamento con i complessi (1) e (3); tale effetto \ue8 dose-dipendente (5-50 \uf06dM) ed \ue8 maggiore rispetto a quello osservato dopo incubazione con il cisplatino. Il complesso (2) non mostra attivit\ue0 citotossica neanche alla dose massima impiegata (50 \uf06dM). La determinazione del valore di IC50 (vedi tabella) ha confermato una maggiore citotossicit\ue0 dei complessi (1) e (3) rispetto al cisplatino. Lo studio del ciclo cellulare, effettuato mediante analisi citofluorimetrica sulle cellule HT29, ha evidenziato che il trattamento con i due composti attivi, rispetto alla condizione controllo, determina un marcato incremento del picco preG0/G1, zona in cui vengono confinate cellule morte con DNA frammentato (apoptosi). Anche in questo caso il trattamento con cisplatino determina effetti meno evidenti. Table: IC50 (\uf06dM) HT29 cells HepG2 cells Cisplatino 58 65 [PtCl(bbp)]Cl (1) 22 26 [(dptdn)(dpt)Pt]Cl2(H2O) (3) 23 2