Exploiting MYC-induced PARPness to target genomic instability in multiple myeloma.

Multiple Myeloma (MM) is a hematologic malignancy strongly characterized by genomic instability, which promotes disease progression and drug resistance. Since we previously demonstrated that LIG3-dependent repair is involved in the genomic instability, drug resistance and survival of MM cells, we here investigated the biological relevance of PARP1, a driver component of Alternative-Non Homologous End Joining (Alt-NHEJ) pathway, in MM. We found a significant correlation between higher PARP1 mRNA expression and poor prognosis of MM patients. PARP1 knockdown or its pharmacological inhibition by Olaparib impaired MM cells viability in vitro and was effective against in vivo xenografts of human MM. Anti-proliferative effects induced by PARP1-inhibition were correlated to increase of DNA double-strand breaks, activation of DNA Damage Response (DDR) and finally apoptosis. Importantly, by comparing a gene expression signature of PARP inhibitors (PARPi) sensitivity to our plasma cell dyscrasia (PC) gene expression profiling (GEP), we identified a subset of MM patients which could benefit from PARP inhibitors. In particular, Gene Set Enrichment Analysis (GSEA) suggested that high MYC expression correlates to PARPi sensitivity in MM. Indeed, we identified MYC as promoter of PARP1-mediated repair in MM and, consistently, we demonstrate that cytotoxic effects induced by PARP inhibition are mostly detectable on MYC-proficient MM cells. Taken together, our findings indicate that MYC-driven MM cells are addicted to PARP1 Alt-NHEJ repair, which represents therefore a druggable target in this still incurable disease.

TERRA G-quadruplex stabilization as a new therapeutic strategy for multiple myeloma.

BACKGROUND: Multiple myeloma (MM) is a hematologic malignancy characterized by high genomic instability, and telomere dysfunction is an important cause of acquired genomic alterations. Telomeric repeat-containing RNA (TERRA) transcripts are long non-coding RNAs involved in telomere stability through the interaction with shelterin complex. Dysregulation of TERRAs has been reported across several cancer types. We recently identified a small molecule, hit 17, which stabilizes the secondary structure of TERRA. In this study, we investigated in vitro and in vivo anti-MM activities of hit 17. METHODS: Anti-proliferative activity of hit 17 was evaluated in different MM cell lines by cell proliferation assay, and the apoptotic process was analyzed by flow cytometry. Gene and protein expressions were detected by RT-qPCR and western blotting, respectively. Microarray analysis was used to analyze the transcriptome profile. The effect of hit 17 on telomeric structure was evaluated by chromatin immunoprecipitation. Further evaluation in vivo was proceeded upon NCI-H929 and AMO-1 xenograft models. RESULTS: TERRA G4 stabilization induced in vitro dissociation of telomeric repeat-binding factor 2 (TRF2) from telomeres leading to the activation of ATM-dependent DNA damage response, cell cycle arrest, proliferation block, and apoptotic death in MM cell lines. In addition, up-regulation of TERRA transcription was observed upon DNA damage and TRF2 loss. Transcriptome analysis followed by gene set enrichment analysis (GSEA) confirmed the involvement of the above-mentioned processes and other pathways such as E2F, MYC, oxidative phosphorylation, and DNA repair genes as early events following hit 17-induced TERRA stabilization. Moreover, hit 17 exerted anti-tumor activity against MM xenograft models. CONCLUSION: Our findings provide evidence that targeting TERRA by hit 17 could represent a promising strategy for a novel therapeutic approach to MM.

miR-21 antagonism abrogates Th17 tumor promoting functions in multiple myeloma.

Multiple myeloma (MM) is tightly dependent on inflammatory bone marrow microenvironment. IL-17 producing CD4+ T cells (Th17) sustain MM cells growth and osteoclasts-dependent bone damage. In turn, Th17 differentiation relies on inflammatory stimuli. Here, we investigated the role of miR-21 in Th17-mediated MM tumor growth and bone disease. We found that early inhibition of miR-21 in naive T cells (miR-21i-T cells) impaired Th17 differentiation in vitro and abrogated Th17-mediated MM cell proliferation and osteoclasts activity. We validated these findings in NOD/SCID-g-NULL mice, intratibially injected with miR-21i-T cells and MM cells. A Pairwise RNAseq and proteome/phosphoproteome analysis in Th17 cells demonstrated that miR-21 inhibition led to upregulation of STAT-1/-5a-5b, STAT-3 impairment and redirection of Th17 to Th1/Th2 like activated/polarized cells. Our findings disclose the role of miR-21 in pathogenic Th17 activity and open the avenue to the design of miR-21-targeting strategies to counteract microenvironment dependence of MM growth and bone disease.

Therapeutic afucosylated monoclonal antibody and bispecific T-cell engagers for T-cell acute lymphoblastic leukemia.

BACKGROUND: T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive disease with a poor cure rate for relapsed/resistant patients. Due to the lack of T-cell restricted targetable antigens, effective immune-therapeutics are not presently available and the treatment of chemo-refractory T-ALL is still an unmet clinical need. To develop novel immune-therapy for T-ALL, we generated an afucosylated monoclonal antibody (mAb) (ahuUMG1) and two different bispecific T-cell engagers (BTCEs) against UMG1, a unique CD43-epitope highly and selectively expressed by T-ALL cells from pediatric and adult patients. METHODS: UMG1 expression was assessed by immunohistochemistry (IHC) on a wide panel of normal tissue microarrays (TMAs), and by flow cytometry on healthy peripheral blood/bone marrow-derived cells, on 10 different T-ALL cell lines, and on 110 T-ALL primary patient-derived cells. CD43-UMG1 binding site was defined through a peptide microarray scanning. ahuUMG1 was generated by Genetic Glyco-Engineering technology from a novel humanized mAb directed against UMG1 (huUMG1). BTCEs were generated as IgG1-(scFv)2 constructs with bivalent (2+2) or monovalent (2+1) CD3ε arms. Antibody dependent cellular cytotoxicity (ADCC), antibody dependent cellular phagocytosis (ADCP) and redirected T-cell cytotoxicity assays were analysed by flow cytometry. In vivo antitumor activity of ahUMG1 and UMG1-BTCEs was investigated in NSG mice against subcutaneous and orthotopic xenografts of human T-ALL. RESULTS: Among 110 T-ALL patient-derived samples, 53 (48.1%) stained positive (24% of TI/TII, 82% of TIII and 42.8% of TIV). Importantly, no expression of UMG1-epitope was found in normal tissues/cells, excluding cortical thymocytes and a minority (<5%) of peripheral blood T lymphocytes. ahUMG1 induced strong ADCC and ADCP on T-ALL cells in vitro, which translated in antitumor activity in vivo and significantly extended survival of treated mice. Both UMG1-BTCEs demonstrated highly effective killing activity against T-ALL cells in vitro. We demonstrated that this effect was specifically exerted by engaged activated T cells. Moreover, UMG1-BTCEs effectively antagonized tumor growth at concentrations >2 log lower as compared with ahuUMG1, with significant mice survival advantage in different T-ALL models in vivo. CONCLUSION: Altogether our findings, including the safe UMG1-epitope expression profile, provide a framework for the clinical development of these innovative immune-therapeutics for this still orphan disease.

DMETTM Genotyping: Tools for Biomarkers Discovery in the Era of Precision Medicine.

The knowledge of genetic variants in genes involved in drug metabolism may be translated into reduction of adverse drug reactions, increase of efficacy, healthcare outcomes improvement and economic benefits. Many high-throughput tools are available for the genotyping of Single Nucleotide Polymorphisms (SNPs) known to be related to drugs and xenobiotics metabolism. DMETTM platform represents an example of SNPs panel to discover biomarkers correlated to efficacy or toxicity in common and rare diseases. The difficulty in analyzing the mole of information generated by DMETTM platform led to the development and implementation of algorithms and tools for statistical and data mining analysis. These softwares allow efficient handling of the omics data to validate the explorative SNPs identified by DMET assay and to correlate them with drug efficacy, toxicity and/or cancer susceptibility. In this review we present a suite of bioinformatic frameworks for the preprocessing and analysis of DMET-SNPs data. In particular, we introduce a workflow that uses the GenoMetric Query Language, a high-level query language specifically designed for genomics, able to query public datasets (such as ENCODE, TCGA, GENCODE annotation dataset, etc.) as well as to combine them with private datasets (e.g., output from Affymetrix® DMETTM Platform).

Polymorphic Variants in NR1I3 and UGT2B7 Predict Taxane Neurotoxicity and Have Prognostic Relevance in Patients With Breast Cancer: A Case-Control Study.

Taxane-related peripheral neuropathy (TrPN) is a dose-limiting toxicity with important interindividual variability. Genetic polymorphisms in absorption, distribution, metabolism, and excretion (ADME) genes may account for variability in drug efficacy and/or toxicity. By the use of Affymetrix drug-metabolizing enzyme and transporter microarray platform, in a retrospective case-control study, the correlation between ADME polymorphic variants and grades ≥ 2-3-TrPN was investigated. In a breast cancer (BC) training set, five single-nucleotide polymorphisms in NR1I3 and UDP-glucuronosyltransferase (UGT)2B7 genes were correlated to grades ≥ 2-3-TrPN protection. By receiver operating characteristic curves, the grades ≥ 2-3-TrPN-related candidate biomarkers in an independent series of 54 patients with BC (17 cases and 37 controls) were validated. NR1I3 was correlated to paclitaxel-TrPN and UGT2B7 to docetaxel-TrPN. Moreover, a genetic signature of prognostic relevance for BC outcome was found. Our findings might have potential relevance for personalized management of patients with BC for prevention of treatment failure in ultrametabolizer genetic variants.

miR-22 suppresses DNA ligase III addiction in multiple myeloma.

Multiple myeloma (MM) is a hematologic malignancy characterized by high genomic instability. Here we provide evidence that hyper-activation of DNA ligase III (LIG3) is crucial for genomic instability and survival of MM cells. LIG3 mRNA expression in MM patients correlates with shorter survival and even increases with more advanced stage of disease. Knockdown of LIG3 impairs MM cells viability in vitro and in vivo, suggesting that neoplastic plasmacells are dependent on LIG3-driven repair. To investigate the mechanisms involved in LIG3 expression, we investigated the post-transcriptional regulation. We identified miR-22-3p as effective negative regulator of LIG3 in MM. Enforced expression of miR-22 in MM cells downregulated LIG3 protein, which in turn increased DNA damage inhibiting in vitro and in vivo cell growth. Taken together, our findings demonstrate that myeloma cells are addicted to LIG3, which can be effectively inhibited by miR-22, promoting a novel axis of genome stability regulation.

The potential role of miRNAs in multiple myeloma therapy.

INTRODUCTION: MicroRNAs (miRNAs) are short non-coding RNAs that are crucial players as post-transcriptional regulators of messenger RNAs (mRNAs). miRNA deregulation has been associated to the pathogenesis of several human malignancies, since they might potentially regulate relevant pathways involved in cancer onset and progression. Therefore, targeting the miRNA network could represent a promising therapeutic strategy for human cancer. Area covered: This review summarizes recent findings on miRNAs as therapeutics or therapeutic targets against multiple myeloma (MM) and its microenvironment, including the challenges to overcome in the next future for the clinical application of this innovative therapeutic approach. Expert commentary: The rising body of advanced preclinical evidence on the biological activity of miRNAs in the pathobiology of MM strongly supports the therapeutic potential of treatment for this still incurable disease. However, translation of this therapeutic strategy for MM patients requires the development of optimized delivery systems and efficient integration of 'omics' data with clinical evidence, to precisely identify MM patients who may benefit from a novel miRNA-based therapy.

Identification of polymorphic variants associated with erlotinib-related skin toxicity in advanced non-small cell lung cancer patients by DMET microarray analysis.

PURPOSE: Erlotinib is a targeted agent commonly used in advanced non-small cell lung cancer (aNSCLC). However, drug-related skin toxicity often may affect the quality of life of cancer patients and lead to treatment discontinuation. Genetic polymorphisms in drug transporters and metabolizing enzymes play a major role in the interindividual variability in terms of efficacy and toxicity of erlotinib treatment. The aim of our study was to identify genetic determinants in adsorption, distribution, metabolism, and excretion genes influencing skin rash (SR) by the novel drug-metabolizing enzyme and transporter (DMET) microarray Affymetrix platform in aNSCLC patients. METHODS: In a retrospective study, 34 erlotinib-treated aNSCLC patients were genotyped by DMET Plus chip: 23 patients experienced SR (cases), while 11 patients did not (controls). Peripheral blood DNA was genotyped. Genotype association was analyzed by Fisher's exact test, and the toxicity-associated gene sets underwent Ingenuity Pathway Analysis (IPA). RESULTS: Seven SNPs in six genes (CYP27B1, MAT1A1, CHST1, CYP4B1, ADH6, and SLC22A1) were associated with the occurrence of SR or with a protective effect. Specifically, the rs8176345 in CYP27B1 gene was significantly correlated with SR (p = 0.0003, OR 55.55, 95% CI 2.7036-1141.1707). The IPA on SR-related genes highlighted the role of a variety of canonical pathways including 1,25-dihydroxyvitamin D3 biosynthesis, S-adenosyl-L-methionine biosynthesis, and methionine degradation I (to homocysteine) in SR development. CONCLUSION: Although exploratory, this study indicates rs8176345 in CYP27B1 gene as significantly correlated with erlotinib-induced SR in aNSCLC patients probably through a mechanism mediated by vitamin D3 and inflammation at skin level.

Targeting of multiple myeloma-related angiogenesis by miR-199a-5p mimics: in vitro and in vivo anti-tumor activity.

Multiple myeloma (MM) cells induce relevant angiogenic effects within the human bone marrow milieu (huBMM) by the aberrant expression of angiogenic factors. Hypoxia triggers angiogenic events within the huBMM and the transcription factor hypoxia-inducible factor-1α (HIF-1α) is over-expressed by MM cells. Since synthetic miR-199a-5p mimics negatively regulates HIF-1α, we here investigated a miRNA-based therapeutic strategy against hypoxic MM cells. We indeed found that enforced expression of miR-199a-5p led to down-modulated expression of HIF-1α as well as of other pro-angiogenic factors such as VEGF-A, IL-8, and FGFb in hypoxic MM cells in vitro. Moreover, miR-199a-5p negatively affected MM cells migration, while it increased the adhesion of MM cells to bone marrow stromal cells (BMSCs) in hypoxic conditions. Furthermore, transfection of MM cells with miR-199a-5p significantly impaired also endothelial cells migration and down-regulated the expression of endothelial adhesion molecules such as VCAM-1 and ICAM-1. Finally, we identified a hypoxia\AKT/miR-199a-5p loop as a potential molecular mechanism responsible of miR-199a-5p down-regulation in hypoxic MM cells. Taken together our results indicate that miR-199a-5p has an important role for the pathogenesis of MM and support the hypothesis that targeting angiogenesis via a miRNA/HIF-1α pathway may represent a novel potential therapeutical approach for this still lethal disease.

Sphingosine analog fingolimod (FTY720) increases radiation sensitivity of human breast cancer cells in vitro.

Radiotherapy is one of the most effective therapeutic strategies for breast cancer patients, although its efficacy may be reduced by intrinsic radiation resistance of cancer cells. Recent investigations demonstrate a link between cancer cell radio-resistance and activation of sphingosine kinase (SphK1), which plays a key role in the balance of lipid signaling molecules. Sphingosine kinase (SphK1) activity can alter the sphingosine-1-phosphate (S1P)/ceramide ratio leading to an imbalance in the sphingolipid rheostat. Fingolimod (FTY720) is a novel sphingosine analog and a potent immunosuppressive drug that acts as a SphK1 antagonist, inhibits the growth, and induces apoptosis in different human cancer cell lines. We sought to investigate the in vitro radiosensitizing effects of FTY720 on the MDA-MB-361 breast cancer cell line and to assess the effects elicited by radiation and FTY720 combined treatments. We found that FTY720 significantly increased anti-proliferative and pro-apoptotic effects induced by a single dose of ionizing radiation while causing autophagosome accumulation. At the molecular level, FTY720 significantly potentiated radiation effects on perturbation of signaling pathways involved in regulation of cell cycle and apoptosis, such as PI3K/AKT and MAPK. In conclusion, our data highlight a potent radiosensitizing effect of FTY720 on breast cancer cells and provide the basis of novel therapeutic strategies for breast cancer treatment.

In vitro and in vivo activity of a novel locked nucleic acid (LNA)-inhibitor-miR-221 against multiple myeloma cells.

BACKGROUND & AIM: The miR-221/222 cluster is upregulated in malignant plasma cells from multiple myeloma (MM) patients harboring the t(4;14) translocation. We previously reported that silencing of miR-221/222 by an antisense oligonucleotide induces anti-MM activity and upregulates canonical miR-221/222 targets. The in vivo anti-tumor activity occurred when miR-221/222 inhibitors were delivered directly into MM xenografts. The aim of the present study was to evaluate the anti-MM activity of a novel phosphorothioate modified backbone 13-mer locked nucleic acid (LNA)-Inhibitor-miR-221 (LNA-i-miR-221) specifically designed for systemic delivery. METHODS: In vitro anti-MM activity of LNA-i-miR-221 was evaluated by cell proliferation and BrdU uptake assays. In vivo studies were performed with non-obese diabetic/severe combined immunodeficient (NOD.SCID) mice bearing t(4;14) MM xenografts, which were intraperitoneally or intravenously treated with naked LNA-i-miR-221. RNA extracts from retrieved tumors were analyzed for miR-221 levels and modulation of canonical targets expression. H&E staining and immunohistochemistry were performed on retrieved tumors and mouse vital organs. RESULTS: In vitro, LNA-i-miR-221 exerted strong antagonistic activity against miR-221 and induced upregulation of the endogenous target p27Kip1. It had a marked anti-proliferative effect on t(4;14)-translocated MM cells but not on MM cells not carrying the translocation and not overexpressing miR-221. In vivo, systemic treatment with LNA-i-miR-221 triggered significant anti-tumor activity against t(4;14) MM xenografts; it also induced miR-221 downregulation, upregulated p27Kip1 and reduced Ki-67. No behavioral changes or organ-related toxicity were observed in mice as a consequence of treatments. CONCLUSIONS: LNA-i-miR-221 is a highly stable, effective agent against t(4;14) MM cells, and is suitable for systemic use. These data provide the rationale for the clinical development of LNA-i-miR-221 for the treatment of MM.

Increased frequency of circulating invariant natural killer T cells in malignant pleural mesothelioma patients.

Invariant natural killer T (iNKT) cells are a distinct subset of human T cells, which expresses an invariant T cell receptor Vα24 Jα18 and recognizes glycolipid antigens in the context of CD1d molecules. iNKT cells exert pivotal regulatory roles in many immune responses, including antitumor immune responses. Alterations in iNKT cell frequency, phenotype, and activation state have been reported in cancer patients. No data are available on the iNKT cells in malignant pleural mesothelioma (MPM), a rare, but very aggressive, malignancy of the pleura with a very poor prognosis. Here, we studied the frequency, phenotype, and cytokine profile of circulating iNKT cells in MPM patients, and correlated results with tumor histological types (epithelioid, sarcomatoid, biphasic) and clinical stages (I-III). We found that the iNKT cell frequency was significantly increased in MPM patients with epithelioid and sarcomatoid types in comparison with healthy volunteers (HV); only three biphasic mesotheliomas were available in this study, thus no conclusions can be drawn for this MPM type. The increased frequency significantly correlates with the clinical stage of tumor with the highest value at the stage III in both epithelioid and sarcomatoid subtypes. According to the histological types, we measured changes in the frequencies of CD4⁺ CD8⁺ (DP) and CD4⁻CD8⁻ (DN), but not in the cytokine profiles (IFN-γ/IL-4 expression). These results demonstrate that the frequency of iNKT cells is increased in MPM patients and that this increase correlates with MPM type and stage.

Synthetic isoforms of endogenous sulfatides differently modulate indoleamine 2,3-dioxygenase in antigen presenting cells.

AIMS: To investigate whether sulfatides modulate indoleamine 2,3-dioxygenase (IDO)1, a fine-tuned enzymatic mechanism for controlling immune responses, gene expression/function in antigen presenting cells (APC). The relationship between structure and activity (SAR) of newly synthesized sulfatide isoforms (C16:0, C18:0, C22:0, C24:1) was also evaluated. MAIN METHODS: CD1d-transfected THP-1 human cells were used as APC and treated with increasing concentrations (0.01-10µΜ) of each compound for an appropriate period of time. The gene expression and the enzymatic activity of IDO1 were examined using reverse transcription-polymerase chain reaction (RT-PCR) and high performance liquid chromatography (HPLC). Compound-untreated cells were taken as negative, while 1000U/ml interferon (IFN)-γ-treated cells as positive controls. KEY FINDINGS: Not all sulfatides induced the same effect: the basal IDO1 expression was significantly reduced (-48 ± 3% at 0.01µΜ) by C16:0 sulfatide, while it was increased by C18:0 or C24:1 sulfatide (+87 ± 7% and +50 ± 5% at 1µΜ, respectively) over negative controls; C22:0 sulfatide resulted ineffective at all concentrations tested. These effects functionally correlated with changes in IDO1 activity: l-kynurenine contents in the culture media were significantly reduced by C16:0 sulfatide (-29 ± 4% at 0.01µM), while it was increased by C18:0 or C24:1 sulfatide (+61 ± 8% and +48 ± 4% at 1µM, respectively) over negative controls. C22:0 sulfatide resulted ineffective at all concentration tested. SIGNIFICANCE: The overall data demonstrate that specific sulfatide isoforms differently modulate IDO1 in APC. The sulfatide-induced effects are structurally dependent on the length/saturation of their fatty acid chain.