Cisplatin-based chemotherapy is the paradigm of non-smallcell lung cancer (NSCLC) treatment; however, it also induces de novo DNA-hypermethylation, a process that may be involved in the development of drug-resistant phenotypes by inactivating genes required for drug-cytotoxicity. By using an expression microarray analysis, we aimed to identify those genes reactivated in a set of two cisplatin (CDDP) resistant and sensitive NSCLC cell lines after epigenetic treatment. Gene expression, promoter methylation and CDDP-chemoresponse were further analyzed in three matched sets of sensitive/resistant cell lines, 23 human cancer cell lines and 36 NSCLC specimens. Results revealed specific silencing by promoter hypermethylation of IGFBP-3 in CDDP resistant cells, whereas IGFBP-3 siRNA interference, induced resistance to CDDP in sensitive cells (Po0.001). In addition, we found a strong correlation between methylation status and CDDP response in tumor specimens (Po0.001). Thus, stage I patients, whose tumors harbor an unmethylated promoter, had a trend towards increased disease-free survival (DFS). We report that a loss of IGFBP-3 expression, mediated by promoter-hypermethylation, results in a reduction of tumor cell sensitivity to cisplatin in NSCLC. Basal methylation status of IGFBP-3 before treatment may be a clinical biomarker and a predictor of the chemotherapy outcome, helping to identify patients who are most likely to benefit from CDDP therapy alone or in combination with epigenetic treatment.

Purpose: Mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1) dephosphorylates mitogen-activated protein kinase [extracellular signal-regulated kinase (ERK), c-Jun NH 2 -terminal kinase (JNK), and p38], mediates breast cancer chemoresistance, and is repressible by doxorubicin in breast cancer cells. We aimed to characterize doxorubicin effects on MKP-1 and phospho-MAPKs in human breast cancers and to further study the clinical relevance of MKP-1 expression in this disease. Experimental Design: Doxorubicin effects on MKP-1, phospho-ERK1/2 (p-ERK1/2), phospho-JNK (p-JNK), and phospho-p38 were assayed in a panel of human breast cancer cells by Western blot and in human breast cancer were assayed ex vivo by immunohistochemistry (n = 50). MKP-1 expression was also assayed in a range of normal to malignant breast lesions (n = 30) and in a series of patients (n = 96) with breast cancer and clinical follow-up. Results: MKP-1 was expressed at low levels in normal breast and in usual ductal hyperplasia and at high levels in in situ carcinoma. MKP-1 was overexpressed in ∼50% of infiltrating breast carcinomas. Similar to what was observed in breast cancer cell lines, ex vivo exposure of breast tumors to doxorubicin down-regulated MKP-1, and upregulated p-ERK1/2 and p-JNK, in the majority of cases. However, in a proportion of tumors overexpressing MKP-1, doxorubicin did not significantly affect MKP-1 or phospho-MAPKs. With regard to patient outcome, MKP-1 overexpression was an adverse prognostic factor for relapse both by univariate (P < 0.001) and multivariate analysis (P = 0.002). Conclusions: MKP-1 is overexpressed during the malignant transformation of the breast and independently predicts poor prognosis. Furthermore, MKP-1 is repressed by doxorubicin in many human breast cancers.

Six complexes of formula [Ir­(η5:κ1-C5Me4CH2py)­(C,N)]­PF6, where C5Me4CH2py is 2-((2,3,4,5-tetramethylcyclopentadienyl)­methyl)­pyridine, and C,N is 2-phenylpyridine (1), 7,8-benzoquinoline (2), 1-phenylisoquinoline (3), 2-(p-tolyl)­pyridine (4), 4-chloro-2-phenylquinoline (5), or 2-(2,4-difluorophenyl)­pyridine (6), have been synthesized. The cyclopentadienyl ligand bears a tethered pyridine that binds to the metal center, resulting in an Ir­(η5:κ1-C 5Me4CH2pyN) tether-ring structure, as confirmed by the X-ray crystal structures of 1, 2, 4, 5, and 6. Nontether versions of 1 and 2 were synthesized to aid unambiguous correlation between structure and activity. While nontether complexes are highly potent toward MCF7 cancer cells (similar to cisplatin), complexes bearing the tether-ring structure, 1–6, are exceptionally more potent (1–2 orders of magnitude). Additionally, 1–6 disrupt mitochondrial membrane potential (ΔΨ m ) and induce oxidative stress. Internalization studies strongly correlate intracellular accumulation and anticancer activity in tether and nontether complexes. We present a new class of organo-iridium drug candidates bearing a structural feature that results in a leap in anticancer potency.

The NFκB family is composed by five subunits (p65/RelA, c-Rel, RelB, p105-p50/ NFκB 1 , p100-p52/NFκB 2 ) and controls the expression of many genes that participate in cell cycle, apoptosis, and other key cellular processes. In a canonical pathway, NFκB activation depends on the IKK complex activity, which is formed by three subunits (IKKa and IKKb and IKKg/NEMO). There is an alternative NFκB activation pathway that does not require IKKb or IKKg/NEMO, in which RelB is a major player. We report in a panel of human breast cancer cells that the IKK/NFκB system is generally overexpressed in breast cancer cells and there is heterogeneity in expression levels of individual members between different cell lines. Doxorubicin, an anticancer agent used in patients with breast cancer, activated NFκB and appeared to be less effective in cells expressing predominantly members of the canonical IKK/NFκB. Two NFκB inhibitors, bortezomib and NEMO-Binding Domain Inhibitory Peptide, prevented doxorubicin-induced NFκB activation and increased doxorubicin antitumor effects in BT-474 cells. Transient down-regulation of members of the canonical pathway (p65, p52, c-Rel and IKKg/ NEMO) by siRNA in HeLa cells increased doxorubicin cytotoxicity. In contrast, silencing of RelB, a key subunit of the alternative pathway, had no evident effects on doxorubicin cytotoxicity. To conclude, NFκB inhibition sensitized cells to doxorubicin, implying directly p65, p52, c-Rel and IKKg/NEMO subunits in chemoresistance, but not RelB. These findings suggest that selective inhibition of the canonical NFκB pathway is sufficient to improve doxorubicin antitumor effects.

Human gliomas harbour cancer stem cells (CSCs) that evolve along the course of the disease, forming highly heterogeneous subpopulations within the tumour mass. These cells possess self-renewal properties and appear to contribute to tumour initiation, metastasis and resistance to therapy. CSC cultures isolated from surgical samples are considered the best preclinical in vitro model for primary human gliomas. However, it is not yet well characterized to which extent their biological and functional properties change during in vitro passaging in the serum-free culture conditions. Here, we demonstrate that our CSC-enriched cultures harboured from one to several CSC clones from the human glioma sample. When xenotransplanted into mouse brain, these cells generated tumours that reproduced at least three different dissemination patterns found in original tumours. Along the passages in culture, CSCs displayed increased expression of stem cell markers, different ratios of chromosomal instability events, and a varied response to drug treatment. Our findings highlight the need for better characterization of CSC-enriched cultures in the context of their evolution in vitro, in order to uncover their full potential as preclinical models in the studies aimed at identifying molecular biomarkers and developing new therapeutic approaches of human gliomas.

The iridium half‐sandwich complex [Ir(η5:κ1‐C5Me4CH2py)(2‐phenylpyridine)]PF6 is highly cytotoxic: 15–250× more potent than clinically used cisplatin in several cancer cell lines. We have developed a correlative 3D cryo X‐ray imaging approach to specifically localize and quantify iridium within the whole hydrated cell at nanometer resolution. By means of cryo soft X‐ray tomography (cryo‐SXT), which provides the cellular ultrastructure at 50 nm resolution, and cryo hard X‐ray fluorescence tomography (cryo‐XRF), which provides the elemental sensitivity with a 70 nm step size, we have located the iridium anticancer agent exclusively in the mitochondria. Our methodology provides unique information on the intracellular fate of the metallodrug, without chemical fixation, labeling, or mechanical manipulation of the cells. This cryo‐3D correlative imaging method can be applied to a number of biochemical processes for specific elemental localization within the native cellular landscape.

Aquation is often acknowledged as a necessary step for metallodrug activity inside the cell. Hemilabile ligands can be used for reversible metallodrug activation. We report a new family of osmium(II)...

We have analyzed the response of primary cultures derived from tumor specimens of non small cell lung cancer (NSCLC) patients to choline kinase α (ChoKα) inhibitors. ChoKα inhibitors have been demonstrated to increase ceramides levels specifically in tumor cells, and this increase has been suggested as the mechanism that explain its proapoptotic effect in cancer cells. Here, we have investigated the molecular mechanism associated to the intrinsic resistance, and found that other enzyme involved in lipid metabolism, acid ceramidase (ASAH1), is specifically upregulated in resistant tumors. NSCLC cells with acquired resistance to ChoKα inhibitors also display increased levels of ASAH1. Accordingly, ASAH1 inhibition synergistically sensitizes lung cancer cells to the antiproliferative effect of ChoKα inhibitors. Thus, the determination of the levels of ASAH1 predicts sensitivity to targeted therapy based on ChoKα specific inhibition and represents a model for combinatorial treatments of ChoKα inhibitors and ASAH1 inhibitors. Considering that ChoKα inhibitors have been recently approved to enter Phase I clinical trials by the Food and Drug Administration (FDA), these findings are anticipating critical information to improve the clinical outcome of this family of novel anticancer drugs under development.