Modulation of cell growth and cisplatin sensitivity by membrane gamma-glutamyltransferase in melanoma cells.

The plasma membrane enzyme c-glutamyltransferase (GGT) is regarded as critical for the maintenance of intracellular levels of glutathione (GSH). GGT expression has been implicated in drug resistance through elevation of intracellular GSH. The dependence of intracellular GSH on GGT expression was not conclusively ascertained. The present study was designed to investigate the role of GGT and of intracellular GSH levels in modulating proliferation and sensitivity to cisplatin of melanoma cells. GGT transfection resulted in increased growth, both in vitro and in tumour xenografts. In addition, GGT-transfected cells exhibited reduced sensitivity to cisplatin associated with lower DNA platination. A decrease in intracellular GSH levels, rather than an increase, was observed in GGT-transfected cells; moreover, in cysteine-deficient conditions, the expression of GGT did not provide transfected cells with the ability of utilising extracellular GSH. In conclusion, these results indicate that GGTactivity confers a growth advantage unrelated with intracellular glutathione supply, and are consistent with the interpretation that cisplatin resistance is the consequence of modifications of cellular pharmacokinetics as a result of extracellular drug inactivation by thiol metabolites originated by GGT-mediated GSH cleavage

Synthesis and Superpotent Anticancer Activity of Tubulysins Carrying Non-hydrolysable N-Substituents on Tubuvaline

We thank Regione Autonoma della Sardegna RAS (Italy) for economic support by covering in part the costs of this research. I.U. acknowledges RAS for his fellowship (for grant numbers see the Supporting Information)Peer reviewedPostprin

Sulfonates-PMMA nanoparticles conjugates: A versatile system for multimodal application

a b s t r a c t We report herein the viability of a novel nanoparticles (NPs) conjugated system, namely the attachment, based on ionic and hydrophobic interactions, of different sulfonated organic salts to positively charged poly(methylmethacrylate) (PMMA)-based core-shell nanoparticles (EA0) having an high density of ammonium groups on their shells. In this context three different applications of the sulfonates@EA0 systems have been described. In detail, their ability as cytotoxic drugs and pro-drugs carriers was evaluated in vitro on NCI-H460 cell line and in vivo against human ovarian carcinoma IGROV-1 cells. Besides, 8-hydroxypyrene-1,3,6-trisulfonic acid, trisodium salt (HPTS) was chosen for NPs loading, and its internalization as bioimaging probe was evaluated on Hep G2 cells. Overall, the available data support the interest for these PMMA NPs@sulfonates systems as a promising formulation for theranostic applications. In vivo biological data strongly support the potential value of these core-shell NPs as delivery system for negatively charged drugs or biologically active molecules. Additionally, we have demonstrated the ability of these PMMA core-shell nanoparticles to act as efficient carriers of fluorophores. In principle, thanks to the high PMMA NPs external charge density, sequential and very easy post-loading of different sulfonates is achievable, thus allowing the preparation of nanocarriers either with bi-modal drug delivery behaviour or as theranostic systems

Effects of MnDPDP andICRF-187 on Doxorubicin-Induced Cardiotoxicityand Anticancer Activity1

Oxidative stress participates in doxorubicin (Dx)–induced cardiotoxicity. The metal complex MnDPDP and its metaboliteMnPLED possess SOD-mimetic activity, DPDP and PLED have, in addition, high affinity for iron. Mice wereinjected intravenously with MnDPDP, DPDP, or dexrazoxane (ICRF-187). Thirty minutes later, mice were killed, theleft atria were hung in organ baths and electrically stimulated, saline or Dx was added, and the contractility wasmeasured for 60 minutes. In parallel experiments, 10 μM MnDPDP or MnPLED was added directly into the organbath. The effect of MnDPDP on antitumor activity of Dx against two human tumor xenografts (MX-1 and A2780)was investigated. The in vitro cytotoxic activity was studied by co-incubating A2780 cells with MnDPDP, DPDP,and/or Dx. Dx caused a marked reduction in contractile force. In vivo treatment with MnDPDP and ICRF-187 attenuatedthe negative effect of Dx. When added directly into the bath, MnDPDP did not protect, whereas MnPLEDattenuated the Dx effect by approximately 50%. MnDPDP or ICRF-187 did not interfere negatively with the antitumoractivity of Dx, either in vivo or in vitro. Micromolar concentrations of DPDP but not MnDPDP displayed anin vitro cytotoxic activity against A2780 cells. The present results show that MnDPDP, after being metabolized toMnPLED, protects against acute Dx cardiotoxicity. Both in vivo and in vitro experiments show that cardioprotectiontakes place without interfering negatively with the anticancer activity of Dx. Furthermore, the results suggest thatthe previously described cytotoxic in vivo activity of MnDPDP is an inherent property of DPDP. Translational Oncology (2012) 5, 252–259funding agencies|Medical Research Council of Southeast Sweden|FORSS-85191|PledPharma AB||</p

Antitumor activity of miR-34a in peritoneal mesothelioma relies on c-MET and AXL inhibition: persistent activation of ERK and AKT signaling as a possible cytoprotective mechanism

Abstract Background The value of microRNAs (miRNAs) as novel targets for cancer therapy is now widely recognized. However, no information is currently available on the expression/functional role of miRNAs in diffuse malignant peritoneal mesothelioma (DMPM), a rapidly lethal disease, poorly responsive to conventional treatments, for which the development of new therapeutic strategies is urgently needed. Here, we evaluated the expression and biological effects of miR-34a\u2014one of the most widely deregulated miRNAs in cancer and for which a lipid-formulated mimic is already clinically available\u2014in a large cohort of DMPM clinical samples and a unique collection of in house-developed preclinical models, with the aim to assess the potential of a miR-34a-based approach for disease treatment. Methods miR-34a expression was determined by qRT-PCR in 45 DMPM and 7 normal peritoneum specimens as well as in 5 DMPM cell lines. Following transfection with miR-34a mimic, the effects on DMPM cell phenotype, in terms of proliferative potential, apoptotic rate, invasion ability, and cell cycle distribution, were assessed. In addition, three subcutaneous and orthotopic DMPM xenograft models were used to examine the effect of miR-34a on tumorigenicity. The expression of miRNA targets and the activation status of relevant pathways were investigated by western blot. Results miR-34a was found to be down-regulated in DMPM clinical specimens and cell lines compared to normal peritoneal samples. miR-34a reconstitution in DMPM cells significantly inhibited proliferation and tumorigenicity, induced an apoptotic response, and declined invasion ability, mainly through the down-regulation of c-MET and AXL and the interference with the activation of downstream signaling. Interestingly, a persistent activation of ERK1/2 and AKT in miR-34a-reconstituted cells was found to counteract the antiproliferative and proapoptotic effects of miRNA, yet not affecting its anti-invasive activity. Conclusions Our preclinical data showing impressive inhibitory effects induced by miR-34a on DMPM cell proliferation, invasion, and growth in immunodeficient mice strongly suggest the potential clinical utility of a miR-34a-replacement therapy for the treatment of such a still incurable disease. On the other hand, we provide the first evidence of a potential cytoprotective/resistance mechanism that may arise towards miRNA-based therapies through the persistent activation of ..