MiR-205 as predictive biomarker and adjuvant therapeutic tool in combination with trastuzumab.

Trastuzumab is the standard treatment for HER2+ breast cancer (BC) patients, and even though it significantly improved their clinical outcome, 50% of them do not benefit from this drug and disease recurs, underlining the need of reliable predictive biomarkers and new therapeutic strategies. Strikingly, despite all the molecular analyses performed to identify the escape mechanisms behind this resistance, it still represents a question point. MiRNAs have been correlated with occurrence and progression of human cancer, and their potential as clinical tools has emerged in the last years. We previously reported that oncosuppressive miR-205 targets HER3, thus increasing the responsiveness to TKIs lapatinib and gefitinib in preclinical models. Here we demonstrate that HER3 inhibition by miR-205 ectopic expression or siRNA-mediated silencing improves the responsiveness to Trastuzumab in vitro in HER2+ BC cell lines, and that this effect is exerted through impairment of AKT-mediated pathway. Moreover, evaluating a series of 52 HER2+ BC patients treated with adjuvant Trastuzumab, we observed that higher miR-205 expression is significantly associated with better outcome (disease-free survival). In summary, our data indicate that miR-205 could predict Trastuzumab efficacy and that its modulation might be useful as adjuvant treatment to improve the response to the drug.

Vectofusin-1 Promotes RD114-TR-Pseudotyped Lentiviral Vector Transduction of Human HSPCs and T Lymphocytes.

Ex vivo transduction of human CD34+ hematopoietic stem/progenitor cells (hCD34+ HSPCs) and T lymphocytes is a key process that requires high efficiency and low toxicity to achieve effective clinical results. So far, several enhancers have been used to improve this process. Among them, Retronectin highly meliorates VSV-G and RD114-TR pseudotyped lentiviral vector delivery in hCD34+ HSPCs and T lymphocytes. However, Retronectin is expensive and requires pre-coating of culture dishes or bags before cell seeding, resulting in a cumbersome procedure. Recently, an alternative transduction adjuvant has been developed, named Vectofusin-1, whose effect has been demonstrated on gene delivery to cell lines and primary hCD34+ HSPCs by lentiviral vectors pseudotyped with different envelope glycoproteins. In this study, we have focused our analysis on the effect of Vectofusin-1 on the transduction of hCD34+ HSPCs and T lymphocytes by using mostly RD114-TR pseudotyped lentivectors and clinical transduction protocols. Here, we have proved that Vectofusin-1 reproducibly enhances gene delivery to hCD34+ HSPCs and activated T cells without cell toxicity and with efficacy comparable to that of Retronectin. The use of Vectofusin-1 will therefore help to shorten and simplify clinical cell manipulation, especially if automated systems are planned for transducing large-scale clinical lots.

Codon Optimization Leads to Functional Impairment of RD114-TR Envelope Glycoprotein.

Lentiviral vectors (LVs) are a highly valuable tool for gene transfer currently exploited in basic, applied, and clinical studies. Their optimization is therefore very important for the field of vectorology and gene therapy. A key molecule for LV function is the envelope because it guides cell entry. The most commonly used in transiently produced LVs is the vesicular stomatitis virus glycoprotein (VSV-G) envelope, whose continuous expression is, however, toxic for stable LV producer cells. In contrast, the feline endogenous retroviral RD114-TR envelope is suitable for stable LV manufacturing, being well tolerated by producer cells under constitutive expression. We have previously reported successful, transient and stable production of LVs pseudotyped with RD114-TR for good transduction of T lymphocytes and CD34+ cells. To further improve RD114-TR-pseudotyped LV cell entry by increasing envelope expression, we codon-optimized the RD114-TR open reading frame (ORF). Here we show that, despite the RD114-TRco precursor being produced at a higher level than the wild-type counterpart, it is unexpectedly not duly glycosylated, exported to the cytosol, and processed. Correct cleavage of the precursor in the functional surface and transmembrane subunits is prevented in vivo, and, consequently, the unprocessed precursor is incorporated into LVs, making them inactive.

miR-9 and miR-200 Regulate PDGFRß-Mediated Endothelial Differentiation of Tumor Cells in Triple-Negative Breast Cancer.

Organization of cancer cells into endothelial-like cell-lined structures to support neovascularization and to fuel solid tumors is a hallmark of progression and poor outcome. In triple-negative breast cancer (TNBC), PDGFRß has been identified as a key player of this process and is considered a promising target for breast cancer therapy. Thus, we aimed at investigating the role of miRNAs as a therapeutic approach to inhibit PDGFRß-mediated vasculogenic properties of TNBC, focusing on miR-9 and miR-200. In MDA-MB-231 and MDA-MB-157 TNBC cell lines, miR-9 and miR-200 promoted and inhibited, respectively, the formation of vascular-like structures in vitro Induction of endogenous miR-9 expression, upon ligand-dependent stimulation of PDGFRß signaling, promoted significant vascular sprouting of TNBC cells, in part, by direct repression of STARD13. Conversely, ectopic expression of miR-200 inhibited this sprouting by indirectly reducing the protein levels of PDGFRß through the direct suppression of ZEB1. Notably, in vivo miR-9 inhibition or miR-200c restoration, through either the generation of MDA-MB-231-stable clones or peritumoral delivery in MDA-MB-231 xenografted mice, strongly decreased the number of vascular lacunae. Finally, IHC and immunofluorescence analyses in TNBC specimens indicated that PDGFRß expression marked tumor cells engaged in vascular lacunae. In conclusion, our results demonstrate that miR-9 and miR-200 play opposite roles in the regulation of the vasculogenic ability of TNBC, acting as facilitator and suppressor of PDGFRß, respectively. Moreover, our data support the possibility to therapeutically exploit miR-9 and miR-200 to inhibit the process of vascular lacunae formation in TNBC. Cancer Res; 76(18); 5562-72. ©2016 AACR.

RD-MolPack technology for the constitutive production of self-inactivating lentiviral vectors pseudotyped with the nontoxic RD114-TR envelope.

To date, gene therapy with transiently derived lentivectors has been very successful to cure rare infant genetic diseases. However, transient manufacturing is unfeasible to treat adult malignancies because large vector lots are required. By contrast, stable manufacturing is the best option for high-incidence diseases since it reduces the production cost, which is the major current limitation to scale up the transient methods. We have previously developed the proprietary RD2-MolPack technology for the stable production of second-generation lentivectors, based on the RD114-TR envelope. Of note, opposite to vesicular stomatitis virus glycoprotein (VSV-G) envelope, RD114-TR does not need inducible expression thanks to lack of toxicity. Here, we present the construction of RD2- and RD3-MolPack cells for the production of self-inactivating lentivectors expressing green fluorescent protein (GFP) as a proof-of-concept of the feasibility and safety of this technology before its later therapeutic exploitation. We report that human T lymphocytes transduced with self-inactivating lentivectors derived from RD3-MolPack cells or with self-inactivating VSV-G pseudotyped lentivectors derived from transient transfection show identical T-cell memory differentiation phenotype and comparable transduction efficiency in all T-cell subsets. RD-MolPack technology represents, therefore, a straightforward tool to simplify and standardize lentivector manufacturing to engineer T-cells for frontline immunotherapy applications.

Human anti-nucleolin recombinant immunoagent for cancer therapy.

Nucleolin (NCL) is a nucleocytoplasmic protein involved in many biological processes, such as ribosomal assembly, rRNA processing, and mRNA stabilization. NCL also regulates the biogenesis of specific microRNAs (miRNAs) involved in tumor development and aggressiveness. Interestingly, NCL is expressed on the surface of actively proliferating cancer cells, but not on their normal counterparts. Therefore, NCL is an attractive target for antineoplastic treatments. Taking advantage of phage-display technology, we engineered a fully human single-chain fragment variable, named 4LB5. This immunoagent binds NCL on the cell surface, it is translocated into the cytoplasm of target cells, and it abrogates the biogenesis of NCL-dependent miRNAs. Binding of 4LB5 to NCL on the cell surface of a variety of breast cancer and hepatocellular carcinoma cell lines, but not to normal-like MCF-10a breast cells, dramatically reduces cancer cell viability and proliferation. Finally, in orthotopic breast cancer mouse models, 4LB5 administration results in a significant reduction of the tumor volume without evident side effects. In summary, here we describe, to our knowledge, the first anti-NCL single-chain fragment variable displaying antineoplastic activity against established solid tumors, which could represent the prototype of novel immune-based NCL-targeting drugs with clinical potential as diagnostic and therapeutic tools in a wide variety of human cancers.

A set of NF-κB-regulated microRNAs induces acquired TRAIL resistance in lung cancer.

TRAIL (TNF-related apoptosis-inducing ligand) is a promising anticancer agent that can be potentially used as an alternative or complementary therapy because of its specific antitumor activity. However, TRAIL can also stimulate the proliferation of cancer cells through the activation of NF-κB, but the exact mechanism is still poorly understood. In this study, we show that chronic exposure to subtoxic concentrations of TRAIL results in acquired resistance. This resistance is associated with the increase in miR-21, miR-30c, and miR-100 expression, which target tumor-suppressor genes fundamental in the response to TRAIL. Importantly, down-regulation of caspase-8 by miR-21 blocks receptor interacting protein-1 cleavage and induces the activation of NF-κB, which regulates these miRNAs. Thus, TRAIL activates a positive feedback loop that sustains the acquired resistance and causes an aggressive phenotype. Finally, we prove that combinatory treatment of NF-κB inhibitors and TRAIL is able to revert resistance and reduce tumor growth, with important consequences for the clinical practice.

Generation of mouse lines conditionally over-expressing microRNA using the Rosa26-Lox-Stop-Lox system.

MicroRNAs are currently the object of intensive investigation due to their role in a myriad of physiological processes and pathological conditions, such as gene regulation and tumorigenesis. To better understand microRNA function, numerous laboratories have already taken advantage of the available techniques of genome editing in mouse. Here, we describe how to generate genetically engineered mouse lines using the popular Rosa-26 Lox-Stop-Lox Knock-In (Rosa-LSL-KI) targeting. This strategy allows for the selective overexpression of microRNAs of interest when coupled to a tissue-specific Cre-expressing line. The present protocol illustrates in detail both the engineering of the targeting vector and the generation of mutated ES clones ready for injection into mouse blastocysts.

Pleiotropic antitumor effects of the pan-HDAC inhibitor ITF2357 against c-Myc-overexpressing human B-cell non-Hodgkin lymphomas.

Histone deacetylases (HDAC) extensively contribute to the c-Myc oncogenic program, pointing to their inhibition as an effective strategy against c-Myc-overexpressing cancers. We, thus, studied the therapeutic activity of the new-generation pan-HDAC inhibitor ITF2357 (Givinostat®) against c-Myc-overexpressing human B-cell non-Hodgkin lymphomas (B-NHLs). ITF2357 anti-proliferative and pro-apoptotic effects were analyzed in B-NHL cell lines with c-Myc translocations (Namalwa, Raji and DOHH-2), stabilizing mutations (Raji) or post-transcriptional alterations (SU-DHL-4) in relationship to c-Myc modulation. ITF2357 significantly delayed the in vitro growth of all B-NHL cell lines by inducing G1 cell-cycle arrest, eventually followed by cell death. These events correlated with the extent of c-Myc protein, but not mRNA, downregulation, indicating the involvement of post-transcriptional mechanisms. Accordingly, c-Myc-targeting microRNAs let-7a and miR-26a were induced in all treated lymphomas and the cap-dependent translation machinery components 4E-BP1, eIF4E and eIF4G, as well as their upstream regulators, Akt and PIM kinases, were inhibited in function of the cell sensitivity to ITF2357, and, in turn, c-Myc downregulation. In vivo, ITF2357 significantly hampered the growth of Namalwa and Raji xenografts in immunodeficient mice. Noteworthy, its combination with suboptimal cyclophosphamide, achieved complete remissions in most animals and equaled or even exceeded the activity of optimal cyclophosphamide. Collectively, our findings provide the rationale for testing the clinical advantages of adding ITF2357 to current therapies for the still very ominous c-Myc-overexpressing lymphomas. They equally provide the proof-of-concept for its clinical evaluation in rational combination with the promising inhibitors of B-cell receptor and PI3K/Akt/mTOR axis currently in the process of development.

miR-205 hinders the malignant interplay between prostate cancer cells and associated fibroblasts.

AIMS: Tumor microenvironment is a strong determinant for the acquisition of metastatic potential of cancer cells. We have recently demonstrated that cancer-associated fibroblasts (CAFs) elicit a redox-dependent epithelial-mesenchymal transition (EMT) in prostate cancer (PCa) cells, driven by cycloxygenase-2/hypoxia-inducible factor-1 (HIF-1)/nuclear factor-κB pathway and enhancing tumor aggressiveness. Here, we investigated the involvement of microRNAs (miRNAs) in tumor-stroma interplay to identify possible tools to counteract oxidative stress and metastasis dissemination. RESULTS: We found that miR-205 is the most downmodulated miRNA in PCa cells upon CAF stimulation, due to direct transcriptional repression by HIF-1, a known redox-sensitive transcription factor. Rescue experiments demonstrated that ectopic miR-205 overexpression in PCa cells counteracts CAF-induced EMT, thus impairing enhancement of cell invasion, acquisition of stem cell traits, tumorigenicity, and metastatic dissemination. In addition, miR-205 blocks tumor-driven activation of surrounding fibroblasts by reducing pro-inflammatory cytokine secretion. INNOVATION: Overall, such findings suggest miR-205 as a brake against PCa metastasis by blocking both the afferent and efferent arms of the circuit between tumor cells and associated fibroblasts, thus interrupting the pro-oxidant and pro-inflammatory circuitries engaged by reactive stroma. CONCLUSION: The evidence that miR-205 replacement in PCa cells is able not only to prevent but also to revert the oxidative/pro-inflammatory axis leading to EMT induced by CAFs sets the rationale for developing miRNA-based approaches to prevent and treat metastatic disease.

In vivo NCL targeting affects breast cancer aggressiveness through miRNA regulation.

Numerous studies have described the altered expression and the causal role of microRNAs (miRNAs) in human cancer. However, to date, efforts to modulate miRNA levels for therapeutic purposes have been challenging to implement. Here we find that nucleolin (NCL), a major nucleolar protein, posttranscriptionally regulates the expression of a specific subset of miRNAs, including miR-21, miR-221, miR-222, and miR-103, that are causally involved in breast cancer initiation, progression, and drug resistance. We also show that NCL is commonly overexpressed in human breast tumors and that its expression correlates with that of NCL-dependent miRNAs. Finally, inhibition of NCL using guanosine-rich aptamers reduces the levels of NCL-dependent miRNAs and their target genes, thus reducing breast cancer cell aggressiveness both in vitro and in vivo. These findings illuminate a path to novel therapeutic approaches based on NCL-targeting aptamers for the modulation of miRNA expression in the treatment of breast cancer.

Estrogen mediated-activation of miR-191/425 cluster modulates tumorigenicity of breast cancer cells depending on estrogen receptor status.

MicroRNAs (miRNAs), single-stranded non-coding RNAs, influence myriad biological processes that can contribute to cancer. Although tumor-suppressive and oncogenic functions have been characterized for some miRNAs, the majority of microRNAs have not been investigated for their ability to promote and modulate tumorigenesis. Here, we established that the miR-191/425 cluster is transcriptionally dependent on the host gene, DALRD3, and that the hormone 17ß-estradiol (estrogen or E2) controls expression of both miR-191/425 and DALRD3. MiR-191/425 locus characterization revealed that the recruitment of estrogen receptor α (ERα) to the regulatory region of the miR-191/425-DALRD3 unit resulted in the accumulation of miR-191 and miR-425 and subsequent decrease in DALRD3 expression levels. We demonstrated that miR-191 protects ERα positive breast cancer cells from hormone starvation-induced apoptosis through the suppression of tumor-suppressor EGR1. Furthermore, enforced expression of the miR-191/425 cluster in aggressive breast cancer cells altered global gene expression profiles and enabled us to identify important tumor promoting genes, including SATB1, CCND2, and FSCN1, as targets of miR-191 and miR-425. Finally, in vitro and in vivo experiments demonstrated that miR-191 and miR-425 reduced proliferation, impaired tumorigenesis and metastasis, and increased expression of epithelial markers in aggressive breast cancer cells. Our data provide compelling evidence for the transcriptional regulation of the miR-191/425 cluster and for its context-specific biological determinants in breast cancers. Importantly, we demonstrated that the miR-191/425 cluster, by reducing the expression of an extensive network of genes, has a fundamental impact on cancer initiation and progression of breast cancer cells.

Oncosuppressive role of p53-induced miR-205 in triple negative breast cancer.

An increasing body of evidence highlights an intriguing interaction between microRNAs and transcriptional factors involved in determining cell fate, including the well known "genome guardian" p53. Here we show that miR-205, oncosuppressive microRNA lost in breast cancer, is directly transactivated by oncosuppressor p53. Moreover, evaluating miR-205 expression in a panel of cell lines belonging to the highly aggressive triple negative breast cancer (TNBC) subtype, which still lacks an effective targeted therapy and characterized by an extremely undifferentiated and mesenchymal phenotype, we demonstrated that this microRNA is critically down-expressed compared to a normal-like cell line. Re-expression of miR-205 where absent strongly reduces cell proliferation, cell cycle progression and clonogenic potential in vitro, and inhibits tumor growth in vivo, and this tumor suppressor activity is at least partially exerted through targeting of E2F1, master regulator of cell cycle progression, and LAMC1, component of extracellular matrix involved in cell adhesion, proliferation and migration.

Breast cancer and microRNAs: therapeutic impact.

Despite advances in detection and therapies, breast cancer is still the leading cause of cancer death in women worldwide. The etiology of this neoplasm is complex, and both genetic and environmental factors contribute to the complicate scenario. Gene profiling studies have been extensively used over the last decades as a powerful tool to define the signature of different cancers and to predict outcome and response to therapies. More recently, a new class of small (19-25 nucleotides) non-coding RNAs, microRNAs (miRs or miRNAs) has been linked to several human diseases, included cancer. MicroRNAs are involved in temporal and tissue-specific eukaryotic gene regulation,(1) either by translational inhibition or exonucleolytic mRNA decay, targeted through imperfect complementarity between the microRNA and the 3' untranslated region (3'UTR) of the mRNA.(2) Since their ability to potentially target any human mRNA, it is likely that microRNAs are involved in almost every biological process, including cell cycle regulation, cell growth, apoptosis, cell differentiation and stress response.(3) The involvement of microRNAs in the biology of human cancer is supported by an increasing body of experimental evidence, that has gradually switched from profiling studies, as the first breast cancer specific signature reported in 2005 by our group(4) describing an aberrant microRNA expression in different tumor types, to biological demonstrations of the causal role of these small molecules in the tumorigenic process, and the possible implications as biomarkers or therapeutic tools.(5) These more recent studies have widely demonstrated that microRNAs can modulate oncogenic or tumor suppressor pathways, and that, at the same time, their expression can be regulated by oncogenes or tumor suppressor genes. The possibility to modulate microRNA expression both in vitro and in vivo by developing synthetic pre-microRNA molecules or antisense oligonucletides has at the same time provided a powerful tool to a deeper comprehension of the molecular mechanisms regulated by these molecules, and suggested the intriguing and promising perspective of a possible use in therapy. Here we review our current knowledge about the involvement of microRNAs in cancer, focusing particularly on breast cancer, and their potential as diagnostic, prognostic and therapeutic tools.

Interplay between microRNAs and the epigenetic machinery: an intricate network.

microRNAs take their place into the epigenetic world revealing a complicated network of reciprocal interconnections: not only they are able to control gene expression at a post-transcriptional level, thus representing a new important class of regulatory molecules, but they are also directly connected to the epigenetic machinery through a regulatory loop. Indeed, if epigenetic modifications, such as DNA methylation or histone acetylation, have been demonstrated to affect microRNA expression, and to be potentially responsible for the aberrant miRNA regulation observed in cancer, the other side of the coin is represented by the capacity of microRNAs to control the epigenetic machinery directly targeting its enzymatic components. This review will analyze and describe the regulatory loop interconnecting microRNAs and epigenetics, describing either how epigenetics can affect the miRNome, as well as how epi-miRNAs can control the epigenome, particularly focusing on the alterations observed in human cancer.

MicroRNA cluster 221-222 and estrogen receptor alpha interactions in breast cancer.

BACKGROUND: Several lines of evidence have suggested that estrogen receptor alpha (ERalpha)-negative breast tumors, which are highly aggressive and nonresponsive to hormonal therapy, arise from ERalpha-positive precursors through different molecular pathways. Because microRNAs (miRNAs) modulate gene expression, we hypothesized that they may have a role in ER-negative tumor formation. METHODS: Gene expression profiles were used to highlight the global changes induced by miRNA modulation of ERalpha protein. miRNA transfection and luciferase assays enabled us to identify new targets of miRNA 206 (miR-206) and miRNA cluster 221-222 (miR-221-222). Northern blot, luciferase assays, estradiol treatment, and chromatin immunoprecipitation were performed to identify the miR-221-222 transcription unit and the mechanism implicated in its regulation. RESULTS: Different global changes in gene expression were induced by overexpression of miR-221-222 and miR-206 in ER-positive cells. miR-221 and -222 increased proliferation of ERalpha-positive cells, whereas miR-206 had an inhibitory effect (mean absorbance units [AU]: miR-206: 500 AU, 95% confidence interval [CI]) = 480 to 520; miR-221: 850 AU, 95% CI = 810 to 873; miR-222: 879 AU, 95% CI = 850 to 893; P < .05). We identified hepatocyte growth factor receptor and forkhead box O3 as new targets of miR-206 and miR-221-222, respectively. We demonstrated that ERalpha negatively modulates miR-221 and -222 through the recruitment of transcriptional corepressor partners: nuclear receptor corepressor and silencing mediator of retinoic acid and thyroid hormone receptor. CONCLUSIONS: These findings suggest that the negative regulatory loop involving miR-221-222 and ERalpha may confer proliferative advantage and migratory activity to breast cancer cells and promote the transition from ER-positive to ER-negative tumors.

microRNA-205 regulates HER3 in human breast cancer.

An increasing amount of experimental evidence shows that microRNAs can have a causal role in breast cancer tumorigenesis as a novel class of oncogenes or tumor suppressor genes, depending on the targets they regulate. HER2 overexpression is a hallmark of a particularly aggressive subset of breast tumors, and its activation is strictly dependent on the trans-interaction with other members of HER family; in particular, the activation of the PI3K/Akt survival pathway, so critically important in tumorigenesis, is predominantly driven through phosphorylation of the kinase-inactive member HER3. Here, we show that miR-205, down-modulated in breast tumors compared with normal breast tissue, directly targets HER3 receptor, and inhibits the activation of the downstream mediator Akt. The reintroduction of miR-205 in SKBr3 cells inhibits their clonogenic potential and increases the responsiveness to tyrosine-kinase inhibitors Gefitinib and Lapatinib, abrogating the HER3-mediated resistance and restoring a potent proapoptotic activity. Our data describe miR-205 as a new oncosuppressor gene in breast cancer, able to interfere with the proliferative pathway mediated by HER receptor family. Our study also provides experimental evidence suggesting that miR-205 can improve the responsiveness to specific anticancer therapies.

UCbase & miRfunc: a database of ultraconserved sequences and microRNA function.

Four hundred and eighty-one ultraconserved sequences (UCRs) longer than 200 bases were discovered in the genomes of human, mouse and rat. These are DNA sequences showing 100% identity among the three species. UCRs are frequently located at genomic regions involved in cancer, differentially expressed in human leukemias and carcinomas and in some instances regulated by microRNAs (miRNAs). Here we present UCbase & miRfunc, the first database which provides ultraconserved sequences data and shows miRNA function. Also, it links UCRs and miRNAs with the related human disorders and genomic properties. The current release contains over 2000 sequences from three species (human, mouse and rat). As a web application, UCbase & miRfunc is platform independent and it is accessible at http://microrna.osu.edu/.UCbase4.