Studies on the synergic activity of a three-drug cocktail active against cisplatin-resistant human leukemia and carcinoma cells

Objectives. At the light of properties and limits of cisplatin (CDDP) as an anticancer agent, and in view of the potential clinical relevance of the synergic effect of CDDP with the Cu(II)-phen complexes previously reported against T-leukemia cells (Pivetta et al.,Talanta, 2013), my research project was aimed at (1) extending the studies of CDDP-Cu(II)-phen combinations as such, as well as with the addition of a third drug component; (2) determining the potential degree of selectivity of the most synergic drug combinations. Methods. Most studies were focused on the most potent Cu(II)Phen compound (C0), lead of the cupper-phen complex series. Wild type and CDDP-resistant human T-leukemia CEM cells, wild type and CDDP-resistant human ovarian carcinoma A2780 cells, and ex vivo cultures of human peripheral blood lymphocytes from healthy donors, were used as cell models to characterize the cytotoxic activity of both binary and ternary drug combinations. Experimental Design (ED) and Artificial Neural Network (ANN) were used for setting experiments and for evaluation of data. Results. Binary and ternary drug combinations showed statistically significant synergisms either against the CDDP-sensitive and the CDDP-resistant cancer cell models. The three-drug cocktail was the most potent with a markedly higher cytotoxicity against leukemic lymphocytes than against ex vivo healthy proliferating lymphocytes. An ESI-MS study of CDDP-C0 mixed combination showed the formation of copper-platinum adducts which, leading to the release of a phenantroline moiety, may -at least in part- explain the synergism observed in the cell models. In addition, the analysis of phospholipid profiles showed lipid alterations in the CDDP-resistant CEM and A2780 cells with respect to their parental counterparts. Conclusions. Besides of the need of further studies to unveil the molecular target(s) of the triple-drug cocktail, based on the promising selectivity index (SI = 5) for cancer cells, investigations on its effectiveness in a xenograft mice models of human susceptible and CDDP-resistant ovarian carcinoma are on the way

Metabolic and mitochondrial remodelling in cisplatin resistance: studies on ovarian cancer cells and derived cytoplasmic hybrids

The onset of resistance to cisplatin still limits its use in the chemotherapy of ovarian cancer and, despite several mechanisms of resistance have been discovered, they are not exhaustive. The aim of this study was to identify which other pathways are exploited by cancer cells to escape cisplatin cytotoxicity, to possibly prevent or overcome the phenomenon with new pharmacological approaches. The increase of anaerobic glycolysis, even in the presence of oxygen (Warburg effect), is the first observation indicating the alteration of energetic metabolism used by tumor cells as a strategy to adapt and grow independently from the availability of the substrate. This evidence suggested us to investigate the hypothesis that a similar metabolic strategy might be of relevance in resistance to cisplatin. Recently it has been shown that only approximately 1% of intracellular platinum is bound to nuclear DNA, while the great majority of the intracellular drug is available to interact with other nucleophilic sites including but not limited to phospholipids, cytosolic, cytoskeletal and membrane proteins, RNA and mitochondrial DNA. mtDNA, unlike nDNA, does not possess efficient repair systems and is therefore more susceptible to the onset of mutations often associated to cancer development, loss of tumor suppressor, activation of oncogenes and mitochondrial dysfunctions often related with an increase of glycolytic activity. Therefore, the aim of this study was to investigate the energetic metabolism and the mitochondrial function of cisplatin-resistant (C13) and sensitive (2008) ovarian cancer cells with different experimental approaches. Results revealed that resistant cells present a significant reduced respiratory chain activity correlated to a lower mitochondrial mass, altered mitochondrial morphology as well as a metabolomic profile typical of a lipogenic phenotype. To investigate the role of mtDNA and nDNA in the mitochondrial and metabolic remodeling of cisplatin-resistant line, cancer cells (2008-C13) were used to generate transmitochondrial hybrids (H2008-HC13). Mitochondrial DNA of parental and hybrid cells was sequenced, showing similar, almost non pathological, polymorphisms. Interestingly, investigating the energetic metabolism and the mitochondrial structure of hybrids, no differences were observed between H2008 and HC13. These data demonstrated that the metabolic reprogramming of C13 cells was not dependent from mtDNA, but was controlled by nuclear factors. Having regard to these data, the activity of some nuclear transcription factors (HIF-1α, and c-Myc) involved in the metabolic reprogramming of tumor cells, has been evaluated and it has been highlighted a different expression of some of their target genes involved in the glycolytic flux. Finally, the metabolic profile of 2008-C13 cells has been outlined by LC-MS which evidenced some interesting differences in aminoacids, phospholipids and antioxidants content

Supramolecular Luminescent Sensors

There is great need for stand-alone luminescence-based chemosensors that exemplify selectivity, sensitivity, and applicability and that overcome the challenges that arise from complex, real-world media. Discussed herein are recent developments toward these goals in the field of supramolecular luminescent chemosensors, including macrocycles, polymers, and nanomaterials. Specific focus is placed on the development of new macrocycle hosts since 2010, coupled with considerations of the underlying principles of supramolecular chemistry as well as analytes of interest and common luminophores. State-of-the-art developments in the fields of polymer and nanomaterial sensors are also examined, and some remaining unsolved challenges in the area of chemosensors are discussed