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The treatment of tumor cells with HDAC inhibitors (HDACi) induces a range of effects including apoptosis, cell cycle arrest, differentiation and senescence, modulation of immune response, and altered angiogenesis. The single-agent... more
The treatment of tumor cells with HDAC inhibitors (HDACi) induces a range of effects including apoptosis, cell cycle arrest, differentiation and senescence, modulation of immune response, and altered angiogenesis. The single-agent activities of several HDACi have been tested in preclinical and clinical studies and are currently the subject of ongoing clinical trials. Although HDACi have been shown to be effective as a single agent against a defined subset of hematological tumors, less convincing results have been found in the treatment of solid tumors. Since current clinical trials of single-agent HDACi showed limited efficacy, in this review we focus on drug combinations including HDACi with conventional chemotherapeutic agents and novel targeted agents. Particular emphasis has been devoted to combinations effective in solid tumors and to combinations between HDACi and immunotherapies. An outline of novel combination strategies, including a new generation of more potent and specific HDACi (e.g., compounds with adamantine and noradamantane as scaffolds) as well as chemical hybrid molecules, has been provided. The paradoxical role of HDACs as tumor suppressors in developing tumors and as therapeutic targets in established neoplasms has also been considered.
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Drug resistance of tumor cells is recognized as the primary cause of failure of chemotherapeutic treatment of most human tumors. Although pharmacological factors including inadequate drug concentration at the tumor site can contribute to... more
Drug resistance of tumor cells is recognized as the primary cause of failure of chemotherapeutic treatment of most human tumors. Although pharmacological factors including inadequate drug concentration at the tumor site can contribute to clinical resistance, cellular factors play a major role in chemoresistance of several tumors. Although manifestations of resistance are conventionally referred to as acquired or intrinsic on the basis of the initial response to the first therapy, a common feature is the development of a phenotype resistant to a variety of structurally and functionally distinct agents. In both manifestations, drug resistance is a multifactorial phenomenon involving multiple interrelated or independent mechanisms. A heterogeneous expression of involved mechanisms may characterize tumors of the same type or cells of the same tumor and may at least in part reflect tumor progression. The relevant mechanisms that can contribute to cellular resistance include: increased expression of defense factors involved in reducing intracellular drug concentration; alterations in drug-target interaction; and changes in cellular response, in particular increased cell ability to repair DNA damage or tolerate stress conditions, and defects in apoptotic pathways. This chapter presents an overview of the drug resistance mechanisms.
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We read with great interest the Opinion article by Jamie Fletcher and colleagues, ABC transporters in cancer: more than just drug efflux pumps. Nature Rev. Cancer. 10, 147???156 (2010), recently published in Nature Reviews Cancer 1. The... more
We read with great interest the Opinion article by Jamie Fletcher and colleagues, ABC transporters in cancer: more than just drug efflux pumps. Nature Rev. Cancer. 10, 147???156 (2010), recently published in Nature Reviews Cancer 1. The authors underline innovative ...
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Metastasis is the main reason for lung cancer related mortality but little is known about specific determinants of successful dissemination from primary tumors and metastasis initiation. Here we show that CD133+/CXCR4+ cancer initiating... more
Metastasis is the main reason for lung cancer related mortality but little is known about specific determinants of successful dissemination from primary tumors and metastasis initiation. Here we show that CD133+/CXCR4+ cancer initiating cells (CICs) directly isolated from patient-derived xenografts (PDX) of non-small cell lung cancer (NSCLC) are endowed with superior ability to seed and initiate metastasis at distant organs. We additionally report that CXCR4 inhibition successfully prevents the increase of cisplatin-resistant CD133+/CXCR4+ cells in residual tumors and their metastatization. Immunophenotypic analysis of lung tumor cells intravenously injected or spontaneously disseminated to murine lungs, demonstrates the survival advantage and increased colonization ability of a specific subset of CD133+/CXCR4+ with reduced expression of epithelial cell adhesion molecule (EpCAM-), that also shows the greatest in vitro invasive potential. We next prove that recovered disseminated cel...
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The cellular response to the antitumor drug cisplatin is complex, and resistance is widespread. To gain insights into the global transcriptional response and mechanisms of resistance, we used microarrays to exam- ine the fission yeast... more
The cellular response to the antitumor drug cisplatin is complex, and resistance is widespread. To gain insights into the global transcriptional response and mechanisms of resistance, we used microarrays to exam- ine the fission yeast cell response to cisplatin. In two iso- genic strains with differing drug sensitivity, cisplatin ac- tivated a stress response involving glutathione-S-trans- ferase, heat shock, and
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The aim of this study was to investigate cellular response to several ruthenium(III), chromium(III) and rhodium(III) compounds carrying bidentate beta-diketonato ligands: [(acac)--acetylacetonate ligand, (tfac)--trifluoroacetylacetonate... more
The aim of this study was to investigate cellular response to several ruthenium(III), chromium(III) and rhodium(III) compounds carrying bidentate beta-diketonato ligands: [(acac)--acetylacetonate ligand, (tfac)--trifluoroacetylacetonate ligand]. Cell sensitivity studies were performed on several cell lines (A2780, cisplatin-sensitive and -resistant U2-OS and U2-OS/Pt, HeLa, B16) using growth-inhibition assay. Effect of intracellular GSH depletion on cell sensitivity to the agents was analyzed in A2780 cells. Flow cytometry was used to assess apoptosis by Annexin-V-FITC/PI staining, and to analyze induction of caspase-3 activity. Possible DNA binding/damaging affinity was investigated, by inductively coupled mass spectrometry, and by 14C-thymidine / 3H-uridine incorporation assay. Cell sensitivity studies showed that the pattern of sensitivity to Ru(tfac)3 complex of the two cisplatin-sensitive/-resistant osteosarcoma cell lines, U2-OS and U2-OS/Pt, was similar to that of A2780 cells...
Research Interests: Medicinal Chemistry, Flow Cytometry, Cell Cycle, Apoptosis, Caspases, and 4 moreHumans, Chromium, Caspase, and Rhodium
The fission yeast Schizosaccharomyces pombe and the budding yeast Saccharomyces cerevisiae have become valuable tools for the study of basic cellular functions of eukaryotic cells, including DNA repair mechanisms and cell cycle control.... more
The fission yeast Schizosaccharomyces pombe and the budding yeast Saccharomyces cerevisiae have become valuable tools for the study of basic cellular functions of eukaryotic cells, including DNA repair mechanisms and cell cycle control. Since the major signaling pathways and cellular processes involved in cellular response to cytotoxic agents are conserved between yeasts and mammalian cells, these simple eukaryotic systems could be excellent models for the identification of molecular/cellular mechanisms of sensitivity to antitumor drugs. We describe relevant biological features of yeast cells and potential applications derived by their genetic manipulation. In particular, we have outlined the role of genes involved in repair processes and in checkpoint control, with specific reference to genes regulating radiation-sensitivity. Specific examples are provided concerning the use of both yeasts in understanding the mechanism of action of platinum compounds and topoisomerase inhibitors. ...
Research Interests: Genetics, Gene regulation, Drug Discovery, DNA damage, DNA repair, and 16 moreBudding Yeast, New Technology, Humans, Mutation, Animals, Fission yeast, Schizosaccharomyces Pombe, Model System, Genetic Recombination, Pharmacological, Yeasts, Mechanism of action, Genome sequence, Drug Targeting, Antineoplastic Agents, and Cell Cycle Control
The p53 gene plays a critical role in cellular response to DNA damage and has been implicated in the response to platinum compounds in ovarian carcinoma patients. Because taxanes could induce p53-independent apoptosis, we assessed the... more
The p53 gene plays a critical role in cellular response to DNA damage and has been implicated in the response to platinum compounds in ovarian carcinoma patients. Because taxanes could induce p53-independent apoptosis, we assessed the relevance of p53 gene status to response in ovarian carcinoma patients receiving paclitaxel and platinum-containing chemotherapy. Forty-eight previously untreated patients with advanced disease received standard paclitaxel/platinum-based chemotherapy. In tumor specimens collected at the time of initial surgery, before therapy, p53 gene status and expression were examined by single-strand conformation polymorphism, sequence analysis, and immunohistochemical analysis. Microsatellite instability analysis was performed on available samples from 30 patients. Thirty-four (71%) of the 48 patients had a clinical response. Pathologic complete remission was documented in 13 (27%) of 48 patients. p53 mutations were detected in 29 (60%) of 48 tumors. Among the pat...
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Multinuclear platinum compounds have been designed to circumvent the cellular resistance to conventional platinum-based drugs. In an attempt to examine the cellular basis of the preclinical antitumor efficacy of a novel multinuclear... more
Multinuclear platinum compounds have been designed to circumvent the cellular resistance to conventional platinum-based drugs. In an attempt to examine the cellular basis of the preclinical antitumor efficacy of a novel multinuclear platinum compound (BBR 3464) in the treatment of cisplatin-resistant tumors, we have performed a comparative study of cisplatin and BBR 3464 in a human osteosarcoma cell line (U2-OS) and in an in vitro selected cisplatin-resistant subline (U2-OS/Pt). A marked increase of cytotoxic potency of BBR 3464 in comparison with cisplatin in U2-OS cells and a complete lack of cross-resistance in U2-OS/Pt cells were found. A detailed analysis of the cisplatin-resistant phenotype indicated that it was associated with reduced cisplatin accumulation, reduced interstrand cross-link (ICL) formation and DNA platination, microsatellite instability, and reduced expression of the DNA mismatch repair protein PMS2. Despite BBR 3464 charge and molecular size, in U2-OS and U2-O...
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The rapid evolution of techniques for measuring gene expression makes available substantial data which require careful analysis. In particular, relative quantification based on microfluidic cards allows performing of rapid large scale... more
The rapid evolution of techniques for measuring gene expression makes available substantial data which require careful analysis. In particular, relative quantification based on microfluidic cards allows performing of rapid large scale analyses. In the present study, we employed ovarian carcinoma cell lines resistant to cisplatin (IGROV-1/Pt1) or to a camptothecin (IGROV-1CPT/L), both characterized by a complex pattern of resistance to multiple agents, to examine the expression of genes of the superfamily of ATP binding-cassette (ABC) transporters by TaqMan microfluidic cards with the aim of developing an analytical tool to process data in this particular framework. The transcript quantification was based on the comparative threshold cycle method, which compares the expression of a target gene normalized to the expression of one or more reference genes (relative quantification). To process expression of ABC transporters, we applied a statistical procedure based on multivariate approaches and re-sampling techniques. The transporters that were significantly modulated included members of the ABCA, ABCB, ABCC and ABCG subgroups. A consistent up-regulation of ABCC2 as compared with the parental IGROV-1 cell line was observed in the IGROV-1/Pt1 cells, whereas down-regulation of ABCC6 and ABCG1 was found in IGROV-1/CPT-L cells. The use of rigorous analytic tools for gene expression data in preclinical models may lead to the identification of signatures to test in ovarian carcinoma clinical samples. Moreover, the developed procedure may be useful in the analysis of relative quantification data obtained with microfluidic cards in different experimental settings.
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Multinuclear platinum complexes are characterized by a peculiar DNA binding mode and higher cytotoxic potency than the mononuclear complexes, and efficacy against a wide range of preclinical tumor models. To reduce the high irreversible... more
Multinuclear platinum complexes are characterized by a peculiar DNA binding mode and higher cytotoxic potency than the mononuclear complexes, and efficacy against a wide range of preclinical tumor models. To reduce the high irreversible plasma protein binding and improve the chemical and metabolic drug stability, novel bis-platinum complexes were designed starting from the parent compound CT-3610. The novel second-generation bis-platinum complexes utilize alkylcarboxylate as leaving groups to improve their pharmacokinetic and pharmacodynamic profiles, thus overcoming the limitations of the previously developed multinuclear compounds. The selected compounds [CT-47518 and CT-47463, respectively (bis-capronate) platinum and (bis-butyrate) platinum], have similar in vitro degradation kinetics in human and murine plasma and, above all, an increased stability when compared to CT-3610, particularly in human plasma. In addition, both compounds exhibited a marked cytotoxic potency as compared with cisplatin and oxaliplatin. Interestingly, they were capable of overcoming resistance mediated by DNA mismatch repair defects in different cellular models. The complexes showed marked antitumor efficacy in Pt-refractory tumor xenografts, with remarkable activity in terms of tumor growth inhibition and tumor growth delay. The improved stability profile in human plasma compared to early bis- and triplatinum complexes together with the marked activity in cellular systems as well as in in vivo models, make CT-47518 and CT-47463 attractive candidates for further development.
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ATP binding cassette transporters are implicated in multidrug resistant phenotypes of tumor cells and may be cancer stem cell markers. Inhibitors of drug efflux pumps represent an emerging group of potentially useful agents for the... more
ATP binding cassette transporters are implicated in multidrug resistant phenotypes of tumor cells and may be cancer stem cell markers. Inhibitors of drug efflux pumps represent an emerging group of potentially useful agents for the improvement of antitumor therapy. Here we provide an overview of drug transporter functions and modulation.
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Small molecules targeting p53 represent an emerging group of potentially useful agents for the improvement of antitumor therapy. These modulators include agents that activate wild-type p53 or reactivate mutant p53 and inhibitors of p53... more
Small molecules targeting p53 represent an emerging group of potentially useful agents for the improvement of antitumor therapy. These modulators include agents that activate wild-type p53 or reactivate mutant p53 and inhibitors of p53 functions. Preclinical evidences support the interest of combination strategies with conventional antitumor agents.
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Since response to platinum-based therapy in non-small-cell lung cancer (NSCLC) is poor, the present study was designed to rationally identify novel drug combinations in cell models including the A549 cell line and the cisplatin-resistant... more
Since response to platinum-based therapy in non-small-cell lung cancer (NSCLC) is poor, the present study was designed to rationally identify novel drug combinations in cell models including the A549 cell line and the cisplatin-resistant subline A549/Pt, characterized by reduced sensitivity to cisplatin-induced apoptosis and by upregulation of efflux transporters of the ATP binding cassette (ABC) superfamily. Given the molecular features of these cells, we focused on compounds triggering apoptosis through different mechanisms, such as the mitochondria-targeting drug arsenic trioxide and the phenanthridine analog sanguinarine, which induce apoptosis through the extrinsic pathway. Sanguinarine, not recognized by ABC transporters, could overcome cisplatin resistance and, when used in combination with arsenic trioxide, was synergistic in A549 and A549/Pt cells. The arsenic trioxide/sanguinarine cotreatment upregulated genes implicated in apoptosis activation through the extrinsic pathway. Drug combination experiments indicated that tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) treatment improved arsenic trioxide/sanguinarine efficacy, a feature associated with a striking apoptosis induction, particularly in the cisplatin-resistant variant. Thus, a synergistic interaction between sanguinarine and arsenic trioxide could be obtained independent of relative cell sensitivity to arsenic trioxide, and an enhanced apoptosis induction could be achieved in combination with TRAIL through modulation of the extrinsic apoptotic pathway. Antitumor activity studies supported the interest of drug combinations including TRAIL in NSCLC, indicating that drug-resistant NSCLC cells can efficiently be killed by the combination of proapoptotic agents. Our results suggest that the molecular changes occurring in treated cells may be exploited to rationally hit surviving cells.
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Multinuclear platinum compounds have been designed to circumvent the cellular resistance to conventional mononuclear platinum-based drugs. In this study we performed a comparative study of cisplatin and of the triplatinum complex BBR 3464... more
Multinuclear platinum compounds have been designed to circumvent the cellular resistance to conventional mononuclear platinum-based drugs. In this study we performed a comparative study of cisplatin and of the triplatinum complex BBR 3464 in a human osteosarcoma cell system (U2-OS) including an in vitro selected cisplatin-resistant subline (U2-OS/Pt). BBR 3464 was extremely potent in comparison with cisplatin in U2-OS cells and completely overcame resistance of U2-OS/Pt cells. In both cell lines, BBR 3464 accumulation and DNA-bound platinum were higher than those observed for cisplatin. On the contrary, a low frequency of interstrand cross-links after exposure to BBR 3464 was found. Differently from the increase of DNA lesions induced by cisplatin, kinetics studies indicated a low persistence of interstrand cross-link formation for BBR 3464. Western blot analysis of DNA mismatch repair proteins revealed a marked decrease of expression of PMS2 in U2-OS/Pt cells, which also exhibited microsatellite instability. Studies on DNA mismatch repair deficient and proficient colon carcinoma cells were consistent with a lack of influence of the DNA mismatch repair status on BBR 3464 cytotoxicity. In conclusion, the cytotoxic potency and the ability of the triplatinum complex to overcome cisplatin resistance appear to be related to a different mechanism of DNA interaction (formation of different types of drug-induced DNA lesions) as compared to conventional mononuclear complexes.
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We previously observed that in yeast cisplatin activates different pathways accounting for stress response. Here, we investigated whether genes involved in yeast drug response were modulated by cisplatin in human tumor cell lines (A2780,... more
We previously observed that in yeast cisplatin activates different pathways accounting for stress response. Here, we investigated whether genes involved in yeast drug response were modulated by cisplatin in human tumor cell lines (A2780, IGROV-1, A431, U2-OS) including cisplatin-resistant sublines (A2780/BBR, IGROV-1/Pt1, A431/Pt and U2-OS/Pt). Factors and pathways involved in stress response (glutathione-S-transferase, proteasome, checkpoint control and recombinational repair) were increased by cisplatin in human tumor sensitive and resistant cells. Moreover, sensitization to cisplatin by pharmacologically targeting glutathione or proteasome was observed in sensitive and resistant cells. Interestingly, only in IGROV-1/Pt1 cells, in which cisplatin up-regulated HSP70 and HSP90, targeting of HSP90 resulted in sensitization of resistant cells, suggesting a protective role of stress response. In conclusion, the present findings support the potential relevance of interfering with heat shock protein response to increase cisplatin cytotoxicity in resistant cells. Overall, pathways activated by cisplatin in human tumor cells appear cell-type specific, at least in part reflecting the stress response observed in yeast.
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The ability of histone deacetylase inhibitors to modulate the expression of genes relevant for growth or apoptotis regulation supports their interest in combination treatments of resistant tumors. We explored the effect of the combination... more
The ability of histone deacetylase inhibitors to modulate the expression of genes relevant for growth or apoptotis regulation supports their interest in combination treatments of resistant tumors. We explored the effect of the combination of the histone deacetylase inhibitor ST2782 and the proteasome inhibitor bortezomib in ovarian carcinoma cell lines, including the IGROV-1 cell line and two p53 mutant platinum-resistant sublines (IGROV-1/OHP and IGROV-1/Pt1). We found a synergistic interaction between the two drugs, more evident in the p53-mutant resistant sublines, which was associated with increa sed apoptosis. The treatment with ST2782 resulted in early induction of Bax as well as in cleavage of caspase 3 and poly (ADP-ribose) polymerase only in the resistant cell lines. The inhibition of p53-transcriptional transactivation by pifithrin alpha in IGROV-1 cells enhanced the synergism. Conversely, knockdown of endogenous wild-type p53 in IGROV-1 cells determined synergism reduction. These opposite effects support the relevance of the transactivation-deficient mutant p53 as a synergism determinant. Moreover, in vivo studies indicated that tumor growth inhibition tended to be more evident in mice receiving the drug combination than in those treated with bortezomib alone. Overall, our study supports the potential effectiveness of the combination in platinum drug-resistant ovarian cancer carrying mutant p53.
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Based on the role of p53 in the control of apoptosis following DNA damage, the status of the TP53 gene has been implicated as a major determinant of tumour responsiveness to cytotoxic therapies. In spite of the high frequency of TP53... more
Based on the role of p53 in the control of apoptosis following DNA damage, the status of the TP53 gene has been implicated as a major determinant of tumour responsiveness to cytotoxic therapies. In spite of the high frequency of TP53 mutations, small-cell lung cancer (SCLC) is recognised as one of the most chemoresponsive solid tumours. Since the relevance of the TP53 gene status in the modulation of tumour responsiveness is dependent on the molecular/biological context, in the present study, we have examined the relationship between chemosensitivity and susceptibility to apoptosis of a TP53-mutant human SCLC cell line. The cell line, in spite of TP53 mutation, retained an efficient response to genotoxic stress as documented by cells ability to modulate the p53 protein, arrest in the G1 and G2 phases of the cell cycle and its marked susceptibility to apoptosis following treatment with DNA damaging agents. Exposure to DNA-damaging agents caused an increase of c-Myc, a DNA damage-responsive transcription factor. An analysis of damage-induced apoptosis in the presence of an anti-Fas/CD95 inhibitory antibody indicated that Fas/CD95 was not required for the apoptotic response. The results support an implication of c-myc in sensitising cells to apoptosis, since inhibition of c-Myc expression with an antisense oligodeoxynucleotide (AS-ODN) almost abolished the drug-induced apoptotic response. In conclusion, the present results support a role for c-myc in the induction of apoptosis by genotoxic stress in the absence of a functional p53 and provide new insights into the mechanisms that may influence apoptosis in TP53-mutant cells. Elucidation of this pathway and of the possible cooperation with p53-dependent mechanisms may provide a basis for therapeutic intervention.
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The proteasome has been regarded as a major target for antitumor therapy in selected tumor types (i.e., multiple myeloma). Available evidence suggests that targeting the proteasome with selective compounds can represent an excellent... more
The proteasome has been regarded as a major target for antitumor therapy in selected tumor types (i.e., multiple myeloma). Available evidence suggests that targeting the proteasome with selective compounds can represent an excellent approach for modulating the response to antitumor agents including both conventional cytotoxic agents and target-specific agents. In fact, promising drug interaction data showing synergistic effects have been reported in cellular studies, both in multiple myeloma and in solid tumors. The mechanistic bases of improved efficacy of drug combinations including bortezomib or other proteasome inhibitors and conventional cytotoxic agents have been in part unravelled and involve the capability of proteasome inhibitors to interfere with the stability of the targets of cytotoxic agents (e.g., topoisomerase inhibitors) as well as with cellular protective pathways (e.g., DNA repair and NF-kB-regulated gene expression). Moreover, the synergistic interaction of proteasome inhibitors and target-specific agents implicates a variety of mechanisms linked to the specific target (e.g., histone deacetylase) modulated by the tailored drug used in combination with the proteasome inhibitor. Several clinical studies are ongoing in an attempt to define drug combination approaches that enhance the efficacy of antitumor treatments. Considering the fast moving field of preclinical research regarding proteasome inhibition, a major contribution to the understanding of the bases of tumor response to treatment with proteasome inhibitors is expected.
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ATP-binding cassette (ABC) transporters are a large family of proteins implicated in physiological cellular functions. Selected components of the family play a well-recognized role in extruding conventional cytotoxic antitumor agents and... more
ATP-binding cassette (ABC) transporters are a large family of proteins implicated in physiological cellular functions. Selected components of the family play a well-recognized role in extruding conventional cytotoxic antitumor agents and molecularly targeted drugs from cells. Some lines of evidence also suggest links between transporters and tumor cell survival, in part unrelated to efflux. However, the study of the precise mechanisms regulating the function of drug transporters (e.g., posttranslational modifications such as glycosylation) is still in its infancy. A better definition of the molecular events clarifying the regulation of transporter levels including regulation by microRNAs may contribute to provide new molecular tools to target such a family of transporters. The present review focuses on the biological aspects that implicate ABC transporters in resistance of tumor cells, including cancer stem cells. Molecular analysis of well-known preclinical systems as well as of cancer stem cell models supports the notion that ABC transporters represent amenable targets for modulation of the efficacy of antitumor agents endowed with different molecular features. Recent achievements regarding tumor cell biology are expected to provide a rationale for developing novel inhibitors that target ABC transporters implicated in drug resistance.
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Cellular resistance to anthracyclines is a major limitation of their clinical use in the treatment of human tumors. Resistance to doxorubicin is described as a multifactorial phenomenon involving the overexpression of defense factors and... more
Cellular resistance to anthracyclines is a major limitation of their clinical use in the treatment of human tumors. Resistance to doxorubicin is described as a multifactorial phenomenon involving the overexpression of defense factors and alterations in drug-target interactions. Such changes do not account for all manifestations of drug resistance, in particular intrinsic resistance of solid tumors. Since anthracyclines can induce apoptotic cell death, an alternative promising approach to drug resistance has focused on the study of cellular response to drug-induced DNA damage, with particular reference to the relationship between cytotoxicity/antitumor efficacy and apoptotic response. The evidence that a novel disaccharide analog (MEN 10755), endowed with an improved preclinical activity over doxorubicin, was also more effective as an inducer of apoptosis provided additional insights to better understand the cellular processes that confer sensitivity to anthracyclines. Although the presence or alteration of a single apoptosis-related factor (e.g., p53, bcl-2) is not predictive of the sensitivity/resistance status, the complex interplay among DNA damage-activated pathways is likely an important determinant of tumor cell sensitivity to anthracyclines
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Platinum drugs are widely used in antitumour therapy and are a cornerstone of the treatment of different solid tumours. The pharmacological interest of cisplatin has led to the design of many analogues to broaden the spectrum of activity,... more
Platinum drugs are widely used in antitumour therapy and are a cornerstone of the treatment of different solid tumours. The pharmacological interest of cisplatin has led to the design of many analogues to broaden the spectrum of activity, reduce side effects, and overcome resistance. Although the cis configuration was initially identified as the only active one, trans-platinum complexes have shown significant antitumour activity in preclinical models. In addition to mononuclear platinum compounds, multinuclear platinum complexes have been generated that are characterised by a different mode of interaction with DNA. Since a major limitation to the clinical efficacy of platinum compounds is drug resistance, the most important feature of nonconventional platinum drugs should be the capability of overcoming cellular resistance. However, due to the multifactorial nature of clinical resistance, which also involves pharmacological factors, the optimisation of current platinum-based therapy also includes the development of drug delivery approaches. The present review focuses on recent studies on the molecular alterations of tumour cells that are associated with resistance to platinum drugs, the development of novel platinum drugs, and approaches that may contribute to improve the efficacy of platinum-based therapy.
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The targeting of specific DNA repair mechanisms may be a promising strategy to improve the efficacy of antitumor therapy. The cytotoxic effects of the clinically relevant topoisomerase 1 (Top1) poison camptothecins are related to the... more
The targeting of specific DNA repair mechanisms may be a promising strategy to improve the efficacy of antitumor therapy. The cytotoxic effects of the clinically relevant topoisomerase 1 (Top1) poison camptothecins are related to the generation of DNA lesions and tumor cells may be resistant to DNA damaging agents due to increased repair. Tyrosyl- DNA phosphodiesterase 1 (TDP1) is implicated in the repair of strand breaks by removing abortive Top1/DNA complexes. Thus, a role for TDP1 in counteracting DNA damage induced by camptothecins has been proposed. Here, we review the role of TDP1 in DNA repair with particular reference to TDP1 function, its cooperation with other pathways and the development of pharmacological inhibitors.
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Although cisplatin is effective in the treatment of different types of tumors, resistance to treatment is a major limitation. In an attempt of overcoming resistance mechanisms, a large effort has been made to generate compounds with a... more
Although cisplatin is effective in the treatment of different types of tumors, resistance to treatment is a major limitation. In an attempt of overcoming resistance mechanisms, a large effort has been made to generate compounds with a different geometry. At present, the most clinically relevant compounds include mononuclear (i.e. oxaliplatin) as well as multinuclear platinum complexes (i.e. BBR 3464). The mechanisms of cellular response to platinum complexes have not been completely elucidated. Among the main pathways affecting cell sensitivity of these drugs a role for p53 has been proposed at least for cisplatin and BBR 3464. Our results indicate that, also in the case of oxaliplatin, cytotoxicity is modulated by this pathway. Indeed, the effect of oxaliplatin could be reduced in tumor cells expressing mutant p53. The DNA mismatch repair system also appears to be critical in regulating cellular sensitivity to cisplatin because the loss of DNA mismatch repair results in low level of resistance to cisplatin, but not to oxaliplatin. Thus, platinum compounds are endowed with differential capability to activate pathways of p53-dependent or independent apoptosis, and differential recognition by specific cellular systems is likely to be the critical determinant of the cell fate (death/survival) after drug exposure. Further molecular studies are required to better define the precise contribution of such pathways to the cellular responses of the clinically relevant platinum complexes. A complete understanding of the molecular basis of sensitivity to platinum drugs is expected to provide useful insights for the optimization of tumor treatment.
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Oligodeoxynucleotides containing unmethylated CpG motifs (CpG-ODN) are potent activators of innate and adaptive immunity. Recognition of CpG-ODN is mediated by Toll-like receptor 9 expressed by immune cells, endothelial and epithelial... more
Oligodeoxynucleotides containing unmethylated CpG motifs (CpG-ODN) are potent activators of innate and adaptive immunity. Recognition of CpG-ODN is mediated by Toll-like receptor 9 expressed by immune cells, endothelial and epithelial cells, and fibroblasts. We examined the antitumor effect of CpG-ODN and the role of administration route on human ovarian cancers growing in the peritoneal cavity of nude mice. Mice implanted i.p. with human ovarian carcinoma cells were treated i.p., s.c., or i.v. and assessed for survival and tumor-free incidence. Peritoneal washings were analyzed for keratinocyte chemokine production and for functional and phenotypic profiles as indicators of the cell types involved in mediating the antitumor effects. IGROV-1-bearing mice treated i.p. survived significantly longer than those treated i.v. or s.c. (P=0.0005), and nearly half of them (8 of 17) were tumor-free by the end of the experiment, a rate never achieved using a variety of chemotherapeutic drugs. High rates of tumor-free mice were observed in three other ovarian tumor xenografts treated i.p. Compared with peritoneal washings of mice treated s.c. or i.v., those from mice treated i.p. showed the highest level of serum and tissue keratinocyte chemokine, the highest number of natural killer cells and neutrophils, and the highest antiproliferative activity in vitro. The superior antitumor effect obtained by locoregional administration of CpG-ODN in i.p. tumor-bearing mice with a limited adaptive immune response points to the importance of innate effector cells amplification at the site of tumor growth and suggests the promise of i.p. CpG-ODN in clinical trials for ovarian cancer.
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The cellular response to the antitumor drug cisplatin is complex, and resistance is widespread. To gain insights into the global transcriptional response and mechanisms of resistance, we used microarrays to examine the fission yeast cell... more
The cellular response to the antitumor drug cisplatin is complex, and resistance is widespread. To gain insights into the global transcriptional response and mechanisms of resistance, we used microarrays to examine the fission yeast cell response to cisplatin. In two isogenic strains with differing drug sensitivity, cisplatin activated a stress response involving glutathione-S-transferase, heat shock, and recombinational repair genes. Genes required for proteasome-mediated protein degradation were up-regulated in the sensitive strain, whereas genes for DNA damage recognition/repair and for mitotic progression were induced in the resistant strain. The response to cisplatin overlaps in part with the responses to cadmium and the DNA-damaging agent methylmethane sulfonate. The different gene groups involved in the cellular response to cisplatin help the cells to tolerate and repair DNA damage and to overcome cell cycle blocks. These findings are discussed with respect to known cisplatin response pathways in human cells.
Research Interests: Physiology, Cell Cycle, DNA damage, Gene expression, Stress response, and 11 moreGlutathione, Fission yeast, Clinical Sciences, Cisplatin, Schizosaccharomyces Pombe, Protein Degradation, Heat Shock, Global Gene Expression, Hydrogen-Ion Concentration, Antineoplastic Agents, and Biochemistry and cell biology
Stable transfection of human ovarian carcinoma cells with survivin cDNA caused a four- to sixfold increase in cell resistance to taxotere and taxol (two-sided Student's t test, p < 0.05), with a concomitant reduction in the... more
Stable transfection of human ovarian carcinoma cells with survivin cDNA caused a four- to sixfold increase in cell resistance to taxotere and taxol (two-sided Student's t test, p < 0.05), with a concomitant reduction in the apoptotic response to taxol, but did not affect cell sensitivity to cisplatin or oxaliplatin. Such findings were indirectly supported by similar observations obtained with clinical tumours. In fact, high levels of survivin protein expression (>30% positive cells), detected by immunohistochemistry in 90/124 (73%) advanced ovarian carcinomas, were significantly associated with clinical resistance to a taxol/platinum-based regimen but unrelated to tumour shrinkage following cisplatin-including combinations (non-taxol based). In the 95 patients receiving a taxol/platinum-based regimen, survivin overexpression correlated with a lower clinical or pathologic complete remission rate than absent/low protein expression (43 vs 75%, p = 0.0058 by logistic regression adjusted for tumour stage, histological grade and p53 expression). Conversely, in the 29 cases treated with cisplatin-containing regimens (not taxol based), survivin expression was unrelated to tumour response. Cellular studies and clinical data suggest a direct link between survivin expression and tumour cell susceptibility to taxol.
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We used cDNA arrays to monitor modulation of mRNA expression after exposure to a multinuclear platinum complex (BBR3464) in a human cervix squamous cell carcinoma cell line (A431) and in a cisplatin-resistant subline (A431/Pt) exhibiting... more
We used cDNA arrays to monitor modulation of mRNA expression after exposure to a multinuclear platinum complex (BBR3464) in a human cervix squamous cell carcinoma cell line (A431) and in a cisplatin-resistant subline (A431/Pt) exhibiting collateral sensitivity to BBR3464. In parental A431cells, the drug induced at least twofold up-regulation of 15 genes including cell cycle and growth regulators, tumor suppressors and signal transduction genes. In cisplatin-resistant A431/Pt cells, BBR3464increased the expression of 15 genes such as apoptosis regulators and genes involved in the DNA damage response. Interestingly, BBR3464induced up-regulation of anti-metastatic factors together with down-regulation of several pro-metastatic factors. Cell cycle analysis indicated a marked G2arrest in treated A431cells, whereas an apoptotic response was documented in A431/Pt cells. These differential patterns of transcriptional profile in sensitive and resistant cells are consistent with a role for cell cycle regulation in the response to BBR3464.
Research Interests: Physiology, Cell Cycle, Apoptosis, Signal Transduction, Cell line, and 13 moreMolecular and cellular biology, Humans, Female, Squamous Cell Carcinoma, Clinical Sciences, mRna expression levels, Oral Squamous Cell Carcinoma (OSCC), DNA damage response, Cell Cycle regulation, Antineoplastic Agents, Biochemistry and cell biology, Gene Expression Regulation, and Gene expression profiling
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Research Interests:
The Schizosaccharomyces pombe rad17 is a checkpoint protein critical for maintenance of genomic stability. Since the loss of checkpoint control is a common feature of tumor cells, we investigated the biological function of the human... more
The Schizosaccharomyces pombe rad17 is a checkpoint protein critical for maintenance of genomic stability. Since the loss of checkpoint control is a common feature of tumor cells, we investigated the biological function of the human homolog hRAD17. Expression of hRAD17 in a fission yeast rad17 deleted strain reduced growth of yeast colonies and caused slower progression through cell cycle. Immunoprecipitated hRad17 exhibited exonuclease activity. hRAD17 delayed growth of NIH3T3 fibroblasts transformed by the H-ras oncogene in nude mice. Our results support that hRAD17, similarly to other human genes involved in checkpoint mechanisms, plays a role in control of tumor growth.