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Multidrug resistance (MDR) is the main obstacle to current chemotherapy and it is mainly due to the overexpression of some efflux transporters such as MRP1. One of the most studied strategies to overcome MDR has been the inhibition of MDR pumps through small molecules, but its translation into the clinic unfortunately failed. Recently, a phenomenon called collateral sensitivity (CS) emerged as a new strategy to hamper MDR acting as a synthetic lethality, where the genetic changes developed upon the acquisition of resistance towards a specific agent are followed by the development of hypersensitivity towards a second agent. Among our library of sigma ligands acting as MDR modulators, we identified three compounds, F397 , F400 , and F421, acting as CS-promoting agents. We deepened their CS mechanisms in the "pure" model of MRP1-expressing cells (MDCK-MRP1) and in MRP1-expressing/drug resistant non-small cell lung cancer cells (A549/DX). The in vitro results demonstrated that (i) the three ligands are highly cytotoxic for MRP1-expressing cells; (ii) their effect is MRP1-mediated; (iii) they increase the cytotoxicity induced by cis-Pt, the therapeutic agent commonly used in the treatment of lung tumors; and (iv) their effect is ROS-mediated. Moreover, a preclinical in vivo study performed in lung tumor xenografts confirms the in vitro findings, making the three CS-promoting agents candidates for a novel therapeutic approach in lung resistant tumors.

P-glycoprotein (Pgp) is highly expressed on blood-brain barrier (BBB) and glioblastoma (GB) cells, particularly on cancer stem cells (SC). Pgp recognizes a broad spectrum of substrates, limiting the therapeutic efficacy of several chemotherapeutic drugs in eradicating GB SC. Finding effective and safe inhibitors of Pgp that improve drug delivery across the BBB and target GB SC is open to investigation. We previously identified a series of thiosemicarbazone compounds that inhibit Pgp with an EC 50 in the nanomolar range, and herein, we investigate the efficacy of three of them in bypassing Pgp-mediated drug efflux in primary human BBB and GB cells. At 10 nM, the compounds were not cytotoxic for the brain microvascular endothelial hCMEC/D3 cell line, but they markedly enhanced the permeability of the Pgp-substrate doxorubicin through the BBB. Thiosemicarbazone derivatives increased doxorubicin uptake in GB, with greater effects in the Pgp-rich SC clones than in the differentiated clones derived from the same tumor. All compounds increased intratumor doxorubicin accumulation and consequent toxicity in GB growing under competent BBB, producing significant killing of GB SC. The compounds crossed the BBB monolayer. The most stable derivative, 10a , had a half-life in serum of 4.2 h. The coadministration of doxorubicin plus 10a significantly reduced the growth of orthotopic GB-SC xenografts, without eliciting toxic side effects. Our work suggests that the thiosemicarbazone compounds are able to transform doxorubicin, a prototype BBB-impermeable drug, into a BBB-permeable drug. Bypassing Pgp-mediated drug efflux in both BBB and GB SC, thiosemicarbazones might increase the success of chemotherapy in targeting GB SC, which represent the most aggressive and difficult components to eradicate.

Dasatinib (DAS) has been licensed for the frontline treatment in chronic myeloid leukemia (CML). However, very few data are available regarding its efficacy and toxicity in elderly patients with CML outside clinical trials. To address this issue, we set out a "real-life" cohort of 65 chronic phase CML patients older than 65 years (median age 75.1 years) treated frontline with DAS in 26 Italian centers from June 2012 to June 2015, focusing our attention on toxicity and efficacy data. One third of patients (20/65: 30.7%) had 3 or more comorbidities and required concomitant therapies; according to Sokal classification, 3 patients (4.6%) were low risk, 39 (60.0%) intermediate risk, and 20 (30.8%) high risk, whereas 3 (4.6%) were not classifiable. DAS starting dose was 100 mg once a day in 54 patients (83.0%), whereas 11 patients (17.0%) received less than 100 mg/day. Grade 3/4 hematologic and extrahematologic toxicities were reported in 8 (12.3%) and 12 (18.5%) patients, respectively. Overall, 10 patients (15.4%) permanently discontinued DAS because of toxicities. Pleural effusions (all WHO grades) occurred in 12 patients (18.5%) and in 5 of them occurred during the first 3 months. DAS treatment induced in 60/65 patients (92.3%) a complete cytogenetic response and in 50/65 (76.9%) also a major molecular response. These findings show that DAS might play an important role in the frontline treatment of CML patients >65 years old, proving efficacy and having a favorable safety profile also in elderly subjects with comorbidities., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

The anti-tumoral effects of cannabinoids have been described in different tumor systems, including pancreatic adenocarcinoma, but their mechanism of action remains unclear. We used cannabinoids specific for the CB1 (ACPA) and CB2 (GW) receptors and metabolomic analyses to unravel the potential pathways mediating cannabinoid-dependent inhibition of pancreatic cancer cell growth. Panc1 cells treated with cannabinoids show elevated AMPK activation induced by a ROS-dependent increase of AMP/ATP ratio. ROS promote nuclear translocation of GAPDH, which is further amplified by AMPK, thereby attenuating glycolysis. Furthermore, ROS determine the accumulation of NADH, suggestive of a blockage in the respiratory chain, which in turn inhibits the Krebs cycle. Concomitantly, inhibition of Akt/c-Myc pathway leads to decreased activity of both the pyruvate kinase isoform M2 (PKM2), further downregulating glycolysis, and glutamine uptake. Altogether, these alterations of pancreatic cancer cell metabolism mediated by cannabinoids result in a strong induction of autophagy and in the inhibition of cell growth.

Pancreatic cancer is an aggressive neoplasia, and standard chemotherapies are by and large ineffective. The purpose of this work was to get a comprehensive preclinical study on the ability of anticancer drug combinations that best inhibit growth of pancreatic adenocarcinoma cells. We evaluated the in vitro growth inhibition of ten pancreatic cancer cell lines to gemcitabine and 5-fluorouracil, newer generation cytotoxic agents (oxaliplatin, irinotecan), targeted therapy (gefitinib) and a histone deacetylase (HDAC) inhibitor (trichostatin A). Cells were treated with the single drug alone and all pairwise drug association. Our results demonstrate that TSA can effectively increase the drug sensitivity of all the cell lines studied. The association of TSA and irinotecan determines an increase in growth inhibition on the highest percentage of cell lines (80%). Our findings may represent an experimental basis for potential clinical application of HDAC inhibitors, in particular in association with drugs used in cancer clinical treatment, supporting the idea that HDAC inhibitors could act as sensitizers for chemotherapy.

Doxorubicin is an anthracycline antibiotic generally used in the treatment of solid tumors, but its use is limited by a severe cardiotoxicity, which has been related to the generation of oxygen- and nitrogen-derived free radicals. We have demonstrated that doxorubicin induces nitric oxide (NO) synthesis in the rat cardiac cells H9c2: the drug, after a 24-h incubation, evoked a dose-dependent increase of both NO synthase (NOS) activity in the cells and nitrite levels in the culture supernatant; the accumulation of nitrite (a stable derivative of NO) was prevented by different NOS inhibitors. The increase of NO production was associated with an increased expression of the inducible NOS isoform gene. These effects were significantly inhibited by the coincubation of doxorubicin with iron nitrilotriacetate, a compound that releases iron into the cells. Our results suggest that doxorubicin could induce NO generation in cardiac cells by modifying the iron homeostasis.

Trimers of bovine pancreatic RNase A were obtained by cross-linking native RNase A with dimethyl suberimidate. They degrade double-stranded RNA more efficiently than dimers and monomers of RNase A, and display significant cytotoxic and/or cytostatic actions against C4-I cells (a human cell line derived from squamous carcinoma of the uterus cervix). On the same cell line cross-linked dimers of RNase A appear to be ineffective.