BRCA1/BARD1-dependent ubiquitination of NF2 regulates Hippo-YAP1 signaling.

Coordination of growth and genomic stability is critical for normal cell physiology. Although the E3 ubiquitin ligase BRCA1 is a key player in maintenance of genomic stability, its role in growth signaling remains elusive. Here, we show that BRCA1 facilitates stabilization of YAP1 protein and turning "off" the Hippo pathway through ubiquitination of NF2. In BRCA1-deficient cells Hippo pathway is "turned On." Phosphorylation of YAP1 is crucial for this signaling process because a YAP1 mutant harboring alanine substitutions (Mt-YAP5SA) in LATS1 kinase recognition sites not only resists degradation but also rescues YAP1 transcriptional activity in BRCA1-deficient cells. Furthermore, an ectopic expression of the active Mt-YAP5SA, but not inactive Mt-YAP6SA, promotes EGF-independent proliferation and tumorigenesis in BRCA1-/- mammary epithelial cells. These findings establish an important role of BRCA1 in regulating stability of YAP1 protein that correlates positively with cell proliferation.

Non-transmissible MV Vector with Segmented RNA Genome Establishes Different Types of iPSCs from Hematopoietic Cells.

Recent advances in gene therapy technologies have enabled the treatment of congenital disorders and cancers and facilitated the development of innovative methods, including induced pluripotent stem cell (iPSC) production and genome editing. We recently developed a novel non-transmissible and non-integrating measles virus (MV) vector capable of transferring multiple genes simultaneously into a wide range of cells through the CD46 and CD150 receptors. The MV vector expresses four genes for iPSC generation and the GFP gene for a period of time sufficient to establish iPSCs from human fibroblasts as well as peripheral blood T cells. The transgenes were expressed differentially depending on their gene order in the vector. Human hematopoietic stem/progenitor cells were directly and efficiently reprogrammed to naive-like cells that could proliferate and differentiate into primed iPSCs by the same method used to establish primed iPSCs from other cell types. The novel MV vector has several advantages for establishing iPSCs and potential future applications in gene therapy.

A pilot study to establish human T-cell leukemia virus type 1 (HTLV-1) carrier model using common marmoset (Callithrix jacchus).

BACKGROUND: For the diagnosis and treatment of adult T-cell leukemia/lymphoma (ATLL) caused by human T-lymphotropic virus type 1 (HTLV-1) are required therapeutic modalities urgently. Non-human primate models for ATLL would provide a valuable information for clinical studies. We did a pilot study to establish an ATLL non-human primate model using common marmosets (Callithrix jacchus). METHODS: We inoculated HTLV-1-producing MT-2 cells into 9-month-old marmosets, either intraperitoneally or intravenously. We next administrated MT-2 cells into 13-month-old marmosets under cyclosporine A (CsA) treatment to promote infection. HTLV-1 infection was determined by measuring HTLV-1 antibody titer in the common marmosets. RESULTS: The HTLV-1 antibody titer increased in the intraperitoneally inoculated marmoset with or without CsA treatment, and it kept over five 5 years though proviral copy number (proviral load, PVL) remained low throughout the study. CONCLUSION: We obtained HTLV-1 asymptomatic carriers of common marmosets by inoculating MT-2 cells.

Transdifferentiation of glioblastoma cells into vascular endothelial cells.

Glioblastoma (GBM) is the most malignant brain tumor and is highly resistant to intensive combination therapies and anti-VEGF therapies. To assess the resistance mechanism to anti-VEGF therapy, we examined the vessels of GBMs in tumors that were induced by the transduction of p53(+/-) heterozygous mice with lentiviral vectors containing oncogenes and the marker GFP in the hippocampus of GFAP-Cre recombinase (Cre) mice. We were surprised to observe GFP(+) vascular endothelial cells (ECs). Transplantation of mouse GBM cells revealed that the tumor-derived endothelial cells (TDECs) originated from tumor-initiating cells and did not result from cell fusion of ECs and tumor cells. An in vitro differentiation assay suggested that hypoxia is an important factor in the differentiation of tumor cells to ECs and is independent of VEGF. TDEC formation was not only resistant to an anti-VEGF receptor inhibitor in mouse GBMs but it led to an increase in their frequency. A xenograft model of human GBM spheres from clinical specimens and direct clinical samples from patients with GBM also showed the presence of TDECs. We suggest that the TDEC is an important player in the resistance to anti-VEGF therapy, and hence a potential target for GBM therapy.

Coxsackievirus A11 is an immunostimulatory oncolytic virus that induces complete tumor regression in a human non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related mortality worldwide. Innovative treatment is required to improve overall survival rates for advanced NSCLC. Oncolytic virotherapy using enteroviruses has emerged as a promising anticancer strategy. To identify a novel, potent virotherapy with an improved safety profile, we assessed the oncolytic activity of 28 enteroviral strains and focused on coxsackievirus A11 (CVA11). CVA11 infection caused extensive oncolytic activity in all three of the examined human NSCLC cell lines, with high intercellular adhesion molecule-1 (ICAM-1) expression associated with greater CVA11-induced cytotoxicity. In vitro inhibition analysis using a pan-caspase inhibitor and western blot detection of cleaved poly (ADP-ribose) polymerase (PARP) indicated that apoptosis partly contributed to CVA11-driven cytotoxicity. CVA11 infection-induced immunogenic cell death in vitro was strongly suggested by substantial calreticulin expression and release of high mobility group box-1 protein (HMGB1). Moreover, in vivo treatment of human NSCLC xenografts with intratumoral CVA11 injection caused complete tumor regression in all treated mice, without significant weight loss. Our findings indicate that novel oncolytic virotherapy utilizing CVA11 may be less toxic and more effective than current treatments for human NSCLC, thus warranting further investigation in clinical trial settings, especially in combination with immunotherapy.

Development of New Oncolytic Virotherapy Targeting Breast Cancer Using Coxsackievirus B3.

BACKGROUND/AIM: Breast cancer is the most common cancer in women worldwide, and triple-negative breast cancer (TNBC) is highly refractory to current standard therapies. Oncolytic virotherapy has recently gathered attention as a new treatment candidate for refractory cancers. MATERIALS AND METHODS: We previously developed a new Coxsackievirus B3 (CVB3) virotherapy targeting lung cancers, and demonstrated that miRNA target sequence insertion into CVB3 reduced its pathogenicity, retaining its original oncolytic activity. In this study, we examined the oncolytic effects of CVB3 against breast cancer cells including TNBC cells. RESULTS: CVB3 infection killed breast cancer cells in a time- and titer-dependent manner, and induced apoptosis. Nude mice transplanted with human TNBC cells were successfully treated with both CVB3-WT and CVB3-HP. Importantly, mice treated with CVB3-HP showed very few adverse events. CONCLUSION: CVB3-HP is a strong oncolytic virus candidate for breast cancer, including TNBC, due to its remarkable oncolytic efficacy and improved safety profile.

Extremely Low Organ Toxicity and Strong Antitumor Activity of miR-34-Regulated Oncolytic Coxsackievirus B3.

Oncolytic virotherapies have emerged as new modalities for cancer treatment. We previously reported that coxsackievirus B3 (CVB3) is a novel oncolytic virus (OV) with a strong ability to lyse human non-small cell lung cancer cells; however, its non-specific toxicity against normal cells remains to be resolved. To improve its safety profile, microRNA target sequences complementary to miR-34a/c, which is expressed preferentially in normal cells, were inserted into the 5' UTR or 3' UTR of the CVB3 genome. In the presence of miR-34a/c, the gene-modified CVB3 could not replicate in normal cells. We also found that the pathogenicity of CVB3 was reduced to a greater extent by targeting miR-34a than miR-34c; in addition, it was more effective to insert the target sequences into the 3' UTR rather than the 5' UTR of the viral genome. Ultimately, we developed a double-miR-34a targeting virus (53a-CVB) by inserting miR-34a targets in both the 5' UTR and 3' UTR of the virus. 53a-CVB was minimally toxic to cells in normal tissue, but maintained nearly its full oncolytic activity in mice xenografted with human lung cancer. 53a-CVB is the first miR-34-regulated OV and represents a promising platform for the development of safe and effective anti-cancer therapies.

Maxizymes and small hairpin-type RNAs that are driven by a tRNA promoter specifically cleave a chimeric gene associated with leukemia in vitro and in vivo.

Many leukemias result from chromosomal translocations that lead to the generation of chimeric oncoproteins. Chimeric gene for the promyelocytic leukemia-retinoic acid receptor alpha (PML-RAR alpha) is the hallmark of acute promyelocytic leukemia. Specific gene silencing of an oncogene is desirable for the treatment of these diseases. We have previously constructed an allosterically controllable ribozyme (designated maxizyme) targeted for bcr-abl chimeric mRNA, whose cleavage activity is induced only in the presence of a specific RNA sequence of interest. It has been demonstrated recently that RNA interference induced by short hairpin-type RNAs provides a powerful method for sequence-specific gene silencing. Here we report that DNA vector-based maxizymes and short hairpin-type RNAs driven by the promoter of a human gene for tRNA(Val) specifically inhibit the expression of the chimeric gene for PML-RAR alpha both in vitro and in vivo. Our findings confirm the potential utility of maxizymes and shRNAs as therapeutic agents.

Targeting NF-κB in glioblastoma: A therapeutic approach.

Glioblastoma multiforme (GBM) is the most common and lethal form of intracranial tumor. We have established a lentivirus-induced mouse model of malignant gliomas, which faithfully captures the pathophysiology and molecular signature of mesenchymal human GBM. RNA-Seq analysis of these tumors revealed high nuclear factor κB (NF-κB) activation showing enrichment of known NF-κB target genes. Inhibition of NF-κB by either depletion of IκB kinase 2 (IKK2), expression of a IκBαM super repressor, or using a NEMO (NF-κB essential modifier)-binding domain (NBD) peptide in tumor-derived cell lines attenuated tumor proliferation and prolonged mouse survival. Timp1, one of the NF-κB target genes significantly up-regulated in GBM, was identified to play a role in tumor proliferation and growth. Inhibition of NF-κB activity or silencing of Timp1 resulted in slower tumor growth in both mouse and human GBM models. Our results suggest that inhibition of NF-κB activity or targeting of inducible NF-κB genes is an attractive therapeutic approach for GBM.

Atypical hypersensitivity to mosquito bites without natural killer cell proliferative disease in an adult patient.

Hypersensitivity to mosquito bites (HMB) is a rare disorder that occurs in the first 2 decades of life and is considered to be associated with chronic Epstein-Barr virus (EBV) infection and natural killer (NK) cell leukemia/lymphoma. EBV-encoded small nuclear RNA (EBER)-positive NK cells infiltrate the skin lesion at the site of the mosquito bite. In this report, we present the case of an adult patient with mantle cell lymphoma complicated by atypical HMB. The anti-EBV antibody titer of the patient indicated reactivation of chronic infection with this virus, and EBV DNA in the peripheral blood mononuclear cells was detected after chemotherapy by quantitative polymerase chain reaction analysis. However, an in situ hybridization analysis did not detect EBER-positive cells in the skin lesion at the bite site or in the lymph node. Peripheral NK cell lymphocytosis and EBV-associated lymphoproliferative disease did not develop. These findings suggest that some patients with chronic EBV infection may develop HMB without NK cell proliferative disease.

Unrelated cord blood transplantation after myeloablative conditioning for adult patients with refractory anemia.

We report the results of unrelated cord blood transplantation (CBT) after myeloablative conditioning in 3 patients with myelodysplastic syndrome-refractory anemia (MDS-RA). All patients were treated with total body irradiation, cytosine arabinoside (Ara-C), and cyclophosphamide, followed by unrelated HLA-mismatched CBT. Granulocyte colony-stimulating factor was infused continuously, starting 12 hours before Ara-C therapy and continuing until the end of Ara-C therapy. All patients received standard cyclosporine and methotrexate therapy as graft-versus-host disease prophylaxis. All patients had myeloid reconstitution, and the times to reach an absolute neutrophil count >0.5 x 10(9)/L were 23, 20, and 26 days. All patients showed full donor chimerism at the time of the first bone marrow examination (on day +42, +43, and +62) after CBT. All patients are alive and free of disease at between 17 and 39 months after CBT. These results suggest that adult MDS-RA patients without suitable related or unrelated bone marrow donors should be considered as candidates for CBT.

Anti-NK cell treatment induces stable mixed chimerism in MHC-mismatched, T cell-depleted, nonmyeloablative bone marrow transplantation.

OBJECTIVE: To clarify natural killer (NK) cell-mediated resistance under cytoreductive conditioning and T cell-depleted bone marrow transplantation, we investigated the effects of host NK cell depletion on engraftment and induction of stable mixed chimerism. METHODS: BALB/c mice (H-2kd) were injected intraperitoneally with anti-asialoGM1 antibody (anti-NK Ab) on day -1. On day 0, they received total body irradiation (TBI) at a dose of 500 cGy, followed by intravenous infusion of 2 x 10(7) T cell-depleted (TCD) bone marrow cells from C57BL/6 mice (H-2kb). Early engraftment and chimerism were determined by the relative ratio of peripheral blood (PB) lymphocytes expressing either H-2kd or H-2kb on day +21. Long-term engraftment and chimerism were evaluated on PB and spleen by multicolor flow cytometry. RESULTS: Although no recipients treated with TBI alone showed engraftment, all the recipients conditioned with anti-NK Ab and TBI showed successful engraftment as well as a donor-dominant pattern of mixed chimerism in both PB and spleen. Spleen cells from recipients with mixed chimerism showed specific tolerance to both host and donor strains, but not to a third party (C3H/He). None of the reconstituted mice showed signs of graft vs host disease, and all survived up to day +330. CONCLUSION: These observations indicate that host NK cell depletion may be used to reduce the intensity of conditioning regimens for engraftment of TCD grafts, and can contribute to establishment of stable mixed chimerism in major histocompatibility complex-mismatched nonmyeloablative transplantation.

Hematopoietic activity of common marmoset CD34 cells isolated by a novel monoclonal antibody MA24.

OBJECTIVE: We focused on a small New World monkey, the common marmoset (Callithrix jacchus), to establish a nonhuman primate model of the treatment of hematological disorders. In this study, we developed the first monoclonal antibodies (MAbs) against marmoset CD34 and tested the in vitro and in vivo hemopoietic activity of cell populations isolated using one of these MAbs. METHODS AND RESULTS: Marmoset cDNA encoding a human CD34 homologue was cloned from bone marrow (BM)-derived RNA using reverse transcription polymerase chain reaction and rapid amplification of cDNA ends. The amino acid sequence of the marmoset CD34 had 81% homology with the human sequence. Five mouse MAbs were raised against marmoset CD34 transfectant. One representative MAb, MA24 (IgM), reacted with approximately 0.5 to 1% of BM mononuclear cells (MNCs), where the colony-forming unit granulocyte/macrophage (CFU-GM) was enriched approximately 11- to 75-fold as compared with the whole BM MNCs. Multilineage differentiation of marmoset CD34+ cells in NOD/SCID mice was confirmed by flow cytometry 1 month after xenotransplantation. CONCLUSION: These results demonstrated that MA24 is useful for the analysis and enrichment of hematopoietic progenitor cells in the marmoset model for preclinical experiments.

Mechanisms of neovascularization and resistance to anti-angiogenic therapies in glioblastoma multiforme.

Glioblastoma multiforme (GBM) is the most malignant brain tumor and highly resistant to intensive combination therapies. GBM is one of the most vascularized tumors and vascular endothelial growth factor (VEGF) produced by tumor cells is a major factor regulating angiogenesis. Successful results of preclinical studies of anti-angiogenic therapies using xenograft mouse models of human GBM cell lines encouraged clinical studies of anti-angiogenic drugs, such as bevacizumab (Avastin), an anti-VEGF antibody. However, these clinical studies have shown that most patients become resistant to anti-VEGF therapy after an initial response. Recent studies have revealed some resistance mechanisms against anti-VEGF therapies involved in several types of cancer. In this review, we address mechanisms of angiogenesis, including unique features in GBMs, and resistance to anti-VEGF therapies frequently observed in GBM. Enhanced invasiveness is one such resistance mechanism and recent works report the contribution of activated MET signaling induced by inhibition of VEGF signaling. On the other hand, tumor cell-originated neovascularization including tumor-derived endothelial cell-induced angiogenesis and vasculogenic mimicry has been suggested to be involved in the resistance to anti-VEGF therapy. Therefore, these mechanisms should be targeted in addition to anti-angiogenic therapies to achieve better results for patients with GBM.

A versatile drug delivery system using streptavidin-tagged pegylated liposomes and biotinylated biomaterials.

Here we have developed a versatile liposome-mediated drug delivery system (DDS) allowing a strong bridge between the streptavidin-tagged liposome (SAL) and biotin (Bi)-tagged biomaterials which has strong affinity to surface proteins expressed in restricted cell lineages. This DDS was effective and specific for many leukemia cells in vitro and in vivo. When examining 6 human leukemia cell lines using calcein-encapsulated SALs in combination with Bi-granulocyte colony-stimulating factor (G-CSF), Bi-anti-CD33 monoclonal antibody (MAb) or Bi-anti-CD7 MAb, the fluorescent positive rate of each cell line was in almost proportion to degree of G-CSF receptor, CD33 or CD7 expression, respectively. More importantly, the binding ability was shown to be well maintained in a mouse xenograft model. Furthermore the cytosine arabinoside (AraC)-encapsulated SALs could kill the corresponding cells much more effectively in combination with Bi-biomaterials than free AraC, as expected. These findings strongly indicate that our SAL/Bi-biomaterial system could allow various types of medical agents to be delivered reliably and stably to the cells targeted.

Dedifferentiation of neurons and astrocytes by oncogenes can induce gliomas in mice.

Glioblastoma multiforme (GBM) is the most common and aggressive malignant primary brain tumor in humans. Here we show that gliomas can originate from differentiated cells in the central nervous system (CNS), including cortical neurons. Transduction by oncogenic lentiviral vectors of neural stem cells (NSCs), astrocytes, or even mature neurons in the brains of mice can give rise to malignant gliomas. All the tumors, irrespective of the site of lentiviral vector injection (the initiating population), shared common features of high expression of stem or progenitor markers and low expression of differentiation markers. Microarray analysis revealed that tumors of astrocytic and neuronal origin match the mesenchymal GBM subtype. We propose that most differentiated cells in the CNS upon defined genetic alterations undergo dedifferentiation to generate a NSC or progenitor state to initiate and maintain the tumor progression, as well as to give rise to the heterogeneous populations observed in malignant gliomas.

Development of a novel mouse glioma model using lentiviral vectors.

We report the development of a new method to induce glioblastoma multiforme in adult immunocompetent mice by injecting Cre-loxP-controlled lentiviral vectors expressing oncogenes. Cell type- or region-specific expression of activated forms of the oncoproteins Harvey-Ras and AKT in fewer than 60 glial fibrillary acidic protein-positive cells in the hippocampus, subventricular zone or cortex of mice heterozygous for the gene encoding the tumor suppressor Tp53 were tested. Mice developed glioblastoma multiforme when transduced either in the subventricular zone or the hippocampus. However, tumors were rarely detected when the mice were transduced in the cortex. Transplantation of brain tumor cells into naive recipient mouse brain resulted in the formation of glioblastoma multiforme-like tumors, which contained CD133(+) cells, formed tumorspheres and could differentiate into neurons and astrocytes. We suggest that the use of Cre-loxP-controlled lentiviral vectors is a novel way to generate a mouse glioblastoma multiforme model in a region- and cell type-specific manner in adult mice.

In vitro validation of bioluminescent monitoring of disease progression and therapeutic response in leukaemia model animals.

PURPOSE: The application of in vivo bioluminescence imaging to non-invasive, quantitative monitoring of tumour models relies on a positive correlation between the intensity of bioluminescence and the tumour burden. We conducted cell culture studies to investigate the relationship between bioluminescent signal intensity and viable cell numbers in murine leukaemia model cells. METHODS: Interleukin-3 (IL-3)-dependent murine pro-B cell line Ba/F3 was transduced with firefly luciferase to generate cells expressing luciferase stably under the control of a retroviral long terminal repeat. The luciferase-expressing cells were transduced with p190 BCR-ABL to give factor-independent proliferation. The cells were cultured under various conditions, and bioluminescent signal intensity was compared with viable cell numbers and the cell cycle stage. RESULTS: The Ba/F3 cells showed autonomous growth as well as stable luciferase expression following transduction with both luciferase and p190 BCR-ABL, and in vivo bioluminescence imaging permitted external detection of these cells implanted into mice. The bioluminescence intensities tended to reflect cell proliferation and responses to imatinib in cell culture studies. However, the luminescence per viable cell was influenced by the IL-3 concentration in factor-dependent cells and by the stage of proliferation and imatinib concentration in factor-independent cells, thereby impairing the proportionality between viable cell number and bioluminescent signal intensity. Luminescence per cell tended to vary in association with the fraction of proliferating cells. CONCLUSION: Although in vivo bioluminescence imaging would allow non-invasive monitoring of leukaemia model animals, environmental factors and therapeutic interventions may cause some discrepancies between tumour burden and bioluminescence intensity.