Abstract 4615: Influence of SF3B1 gene mutation is different from that of Sf3B1 inhibitor in colorectal cancer

Purpose: We have reported that SF3B1 gene mutations are rare in colorectal cancer patients and SF3B1 gene mutations in codon 1074 are responsible for resistance to SF3B1 inhibitor (FR901464, FR) at the AACR annual meeting 2013. SF3B1 gene mutations in hematological malignancies are considered to be related to tumor progression. To elucidate the influence by SF3B1 gene mutation in colorectal cancer, we assessed the tumor growth of colorectal cancer cells bearing SF3B1 gene mutation in vitro and in vivo.

ExperimentalDesign: We assessed the tumor growth in vitro and in vivo using FR resistant clones (DLD/FR1, DLD/FR2, DLD/FR3, HCT/FR1, HCT/FR2, and LoVo/FR1) derived from DLD1, HCT116, and LoVo. We also performed microarray analysis of DLD1, DLD/FR1, HCT116, and HCT/FR1 with or without FR for 24 h to compare the change of gene expression by FR or SF3B1 gene mutation.

Results: Doubling time of growth in DLD/FR1, DLD/FR2, HCT/FR1, and HCT/FR2 in vitro was same as their parental cells. However, doubling time of growth in DLD/FR3 and LoVo/FR1 in vitro was longer than their parental cells. In mouse subcutaneous xenograft models, the tumor volume of DLD1/FR1, HCT/FR1, and HCT/FR2 were 61%, 32 %, and 25%, to compared to that of their parental DLD1 or HCT116 one month after inoculation, respectively. Microarray analysis showed the genes and pathways affected by SF3B1 inhibitor and SF3B1 gene mutation did not match at all. Though SF3B1 inhibitor strongly inhibited pathways related to cell cycle, Fanconi anemia, homologous recombination, ubiquitin mediated proteolysis, nucleotide excision repair, oocyte meiosis, basal transcription factors, and endocytosis, SF3B1 gene mutation did not influence these pathways. The genes influenced by SF3B1 gene mutations included MHC class I/II, MHC MYC, BCL2, IL2, and IL10.

Conclusion: Our data indicated SF3B1 gene mutation in colorectal cancer induced disadvantage in cancer progression by the different pathway from SF3B1 inhibitor.

Citation Format: Tomoki Yamano, Shuji Kubo, Nagahide Matsubara, Aya Yano, Naohiro Tomita. Influence of SF3B1 gene mutation is different from that of Sf3B1 inhibitor in colorectal cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4615. doi:10.1158/1538-7445.AM2014-4615

Highly efficient tumor transduction and antitumor efficacy in experimental human malignant mesothelioma using replicating gibbon ape leukemia virus

Retroviral replicating vectors (RRVs) have been shown to achieve efficient tumor transduction and enhanced therapeutic benefit in a wide variety of cancer models. Here we evaluated two different RRVs derived from amphotropic murine leukemia virus (AMLV) and gibbon ape leukemia virus (GALV), in human malignant mesothelioma cells. In vitro, both RRVs expressing the green fluorescent protein gene efficiently replicated in most mesothelioma cell lines tested, but not in normal mesothelial cells. Notably, in ACC-MESO-1 mesothelioma cells that were not permissive for AMLV-RRV, the GALV-RRV could spread efficiently in culture and in mice with subcutaneous xenografts by in vivo fluorescence imaging. Next, GALV-RRV expressing the cytosine deaminase prodrug activator gene showed efficient killing of ACC-MESO-1 cells in a prodrug 5-fluorocytosine dose-dependent manner, compared with AMLV-RRV. GALV-RRV-mediated prodrug activator gene therapy achieved significant inhibition of subcutaneous ACC-MESO-1 tumor growth in nude mice. Quantitative reverse transcription PCR demonstrated that ACC-MESO-1 cells express higher PiT-1 (GALV receptor) and lower PiT-2 (AMLV receptor) compared with normal mesothelial cells and other mesothelioma cells, presumably accounting for the distinctive finding that GALV-RRV replicates much more robustly than AMLV-RRV in these cells. These data indicate the potential utility of GALV-RRV-mediated prodrug activator gene therapy in the treatment of mesothelioma.

Enhanced antitumor efficacy of fiber-modified, midkine promoter-regulated oncolytic adenovirus in human malignant mesothelioma

Oncolytic virotherapy using adenoviruses has potential for therapeutic benefits in malignant mesothelioma. However, the downregulation of coxsackie virus/adenovirus receptor (CAR) expression is frequently a critical rate-limiting factor that impedes the effectiveness of adenovirus serotype 5 (Ad5)-based vectors in many cancer types. We evaluated CAR (Ad5 receptor) and CD46 (adenovirus serotype 35 [Ad35] receptor) expression in six human malignant mesothelioma cell lines. Very low CAR expression was observed in MSTO-211H and NCI-H2052 cells, whereas the other cell lines showed strong expression. In contrast, CD46 was highly expressed in all mesothelioma cell lines. On this basis, we replaced the CAR binding sequence of Ad5 with the CD46 binding sequence of Ad35 in the replication-defective adenoviruses and the tumor-specific midkine promoter-regulated oncolytic adenoviruses. By this fiber modification, the infectivity, virus progeny production, and in vitro cytocidal effects of the adenoviruses were significantly enhanced in low CAR-expressing MSTO-211H and NCI-H2052 cells, also resulting in similar or even higher levels in high CAR-expressing mesothelioma cell lines. In MSTO-211H xenograft models, the fiber-modified oncolytic adenovirus significantly enhanced antitumor effect compared to its equivalent Ad5-based vector. Our data demonstrate that Ad35 fiber modification of binding tropism in a midkine promoter-regulated oncolytic Ad5 vector confers transductional targeting to oncolytic adenoviruses, thereby facilitating more effective treatment of malignant mesothelioma.

Molecular targeting of hepatocyte growth factor by an antagonist, NK4, in the treatment of rheumatoid arthritis

Introduction

Hepatocyte growth factor (HGF) is a potent proangiogenic molecule that induces neovascularization. The HGF antagonist, NK4, competitively antagonizes HGF binding to its receptor. In the present study, we determined the inhibitory effect of NK4 in a rheumatoid arthritis (RA) model using SKG mice.

Methods

Arthritis was induced in SKG mice by a single intraperitoneal injection of β-glucan. Recombinant adenovirus containing NK4 cDNA (AdCMV.NK4) was also injected intravenously at the time of or 1 month after β-glucan injection. Ankle bone destruction was examined radiographically. The histopathologic features of joints were examined using hematoxylin and eosin and immunohistochemical staining. Enzyme-linked immunosorbent assays were used to determine the serum levels of HGF, interferon γ (IFN-γ, interleukin 4 (IL-4) and IL-17 production by CD4⁺ T cells stimulated with allogeneic spleen cells.

Results

The intravenous injection of AdCMV.NK4 into SKG mice suppressed the progression of β-glucan-induced arthritis. Bone destruction was also inhibited by NK4 treatment. The histopathologic findings of the ankles revealed that angiogenesis, inflammatory cytokines and RANKL expression in synovial tissues were significantly inhibited by NK4 treatment. Recombinant NK4 (rNK4) proteins inhibited IFN-γ, IL-4 and IL-17 production by CD4⁺ T cells stimulated with allogeneic spleen cells.

Conclusions

These results indicate that NK4 inhibits arthritis by inhibition of angiogenesis and inflammatory cytokine production by CD4⁺ T cells. Therefore, molecular targeting of angiogenic inducers by NK4 can potentially be used as a novel therapeutic approach for the treatment of RA.

Abstract 4350: Low frequencies of SF3B1 mutations indicate SF3B1 inhibitor as a novel moleculartargeted drug for colorectal cancer

Purpose: FR901464 (FR) is an antitumor agent that specifically binds to and inhibits the function of splicing factor 3B subunit 1 (SF3B1). Higher frequencies of SF3B1 gene mutations and their relevance to cancer progression have been shown in studies of hematological malignancies.

We assessed the frequencies of SF3B1 gene mutations in colorectal cancer (CRC) and the correlation of SF3B1 mutations and FR sensitivity in CRC.

Experimental Design: We measured FR sensitivity in CRC cell lines to establish FR-resistant clones and performed DNA sequencing of all

25 SF3B1 exons in nine CRC cell lines, FR-resistant clones, and 16 CRC patients.

On the basis our results, we performed further DNA sequencing in 80 CRC patients.

Results: The FR IC50 values in all CRC cell lines were < 1ng/ml. Six FR-resistant clones were established: three from DLD1, two from HCT116, and one from LoVo cells. The FR IC50 of the FR-resistant clones was > 500-fold greater than that of their parental cells, although the IC50 of oxaliplatin or 5-fuluorouracil were the same. We found nonsense mutations in exon 10 of DLD1 cells and no significant mutations in the other samples. All the FR-resistant clones had the missense mutations in codon 1073 of exon 22. We found no mutation in exons 10, 22, and 12-15, which were previously reported in hematological malignancies in 80 CRC patients.

Conclusion: Our data indicated the usefulness of the SF3B1 inhibitor as a novel molecular targeted drug for CRC and the other malignancies without codon 1073 mutations.

Citation Format: Tomoki Yamano, Hidenori Nakajima, Satoshi Tsuda, Shuji Kubo, Mie Hamanaka, Masayoshi Kobayashi, Daisuke Yamagishi, Takashi Kuno, Kiyoshi Tsukamoto, Astuko Tamamoto, Masafumi Noda, Nagahide Matsubara, Dave SB Hoon, Naohiro Tomita. Low frequencies of SF3B1 mutations indicate SF3B1 inhibitor as a novel moleculartargeted drug for colorectal cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4350. doi:10.1158/1538-7445.AM2013-4350

102 REPEATED OVARIAN STIMULATIONS BY EXOGENOUS GONADOTROPIN COULD ALTER ATP CONTENT AND MITOCHONDRIAL DISTRIBUTION IN MOUSE OOCYTES

Ovarian stimulation (OS) by exogenous gonadotropin enhances the availability of mammalian oocytes but compromises their developmental competence (Combelles and Albertini 2003 Biol. Reprod. 68, 812–821). Recently, several studies have reported mitochondrial function-related abnormalities in oocytes after single and repeated OSs. Because mitochondria can directly influence fertilization outcomes (El Shourbagy et al. 2006 Reproduction 131, 233–245), this study aimed to determine the relationship between mitochondria-related parameters and developmental competence on the basis of ATP content, mitochondrial DNA (mtDNA) copy number, mitochondrial distribution, and IVF results for oocytes after repeated OSs. Ovulated oocytes were recovered from ICR female mice treated with 7.5 IU of eCG and 5 IU of hCG at an interval of 48 h in 1 (control) to 3 stimulation cycles, which were performed at intervals of either 5 or 10 d (n = 15–25 in each treatment group). The ATP content in oocytes was determined using a luminometer and commercial kits (BacTiter-Glo; Promega, WI, USA; n = 15–29 in each treatment group). The mtDNA copy number in oocytes was quantified by performing absolute quantification with real-time PCR (n = 4–8 in each treatment group). Mitochondrial distribution in oocytes stained by rhodamine123 was observed under a confocal microscope (n = 12–26 in each treatment group). These analyses were performed only for morphologically normal oocytes. The data were analyzed by one-way ANOVA, followed by Fisher’s least significant difference, or by the chi-square test. Some mice did not ovulate in the third stimulation cycle for both intervals (5-d interval, 32%; 10-d interval, 80%). The mean numbers of ovulated oocytes gradually decreased with progression of the stimulation cycles. The ATP content of the oocytes significantly decreased both in the second and third stimulation cycles, performed with a 5-d interval (control, 1.038 ± 0.117 pmol; second cycle, 0.852 ± 0.189 pmol; third cycle, 0.932 ± 0.272 pmol). The mean mtDNA copy number in oocytes did not change significantly but varied widely in the third stimulation cycle (control, 146 000 ± 21 000; 5-d interval, 135 000 ± 35 000; 10-d interval: 148 000 ± 50 000; mean ± SD). The mitochondrial staining patterns were classified into homogeneous, aggregation, and perinuclear accumulation. The rates of aggregation and perinuclear accumulation increased after repeated stimulation cycles. The blastocyst rates did not significantly differ among the treatment groups after IVF (75–82%). Repeated OSs not only decreased the number of ovulated oocytes but also caused changes related with mitochondrial function, even in the morphologically normal ovulated oocytes. Translocation of active mitochondria, which are associated with energy production, has some functional correlation with successful pre-implantation development (Suzuki et al. 2006 J. Mamm. Ova. Res. 23, 128–134). Changes in mitochondrial distribution might compensate for the negative effect of the decrease in ATP content and low mtDNA copy number after repeated OSs to help reach the blastocyst stage.

Suppression of spurious mode oscillation in mega-watt 77-GHz gyrotron as a high quality probe beam source for the collective Thomson scattering in LHD

Collective Thomson scattering (CTS) diagnostic requires a strong probing beam to diagnose a bulk and fast ion distribution function in fusion plasmas. A mega-watt gyrotron for electron cyclotron resonance heating is used as a probing beam in the large helical device. Spurious mode oscillations are often observed during the turning on/off phase of the modulation. The frequency spectra of the 77-GHz gyrotron output power have been measured, and then one of the spurious modes, which interferes with the CTS receiver system, is identified as the TE(17,6) mode at the frequency of 74.7 GHz. The mode competition calculation indicates that the increase of the magnetic field strength at the gyrotron resonator can avoid such a spurious mode and excite only the main TE(18,6) mode. The spurious radiation at the 74.7 GHz is experimentally demonstrated to be suppressed in the stronger magnetic field than that optimized for the high-power operation.

Cytosine-phosphate-guanosine-DNA induces CD274 expression in human B cells and suppresses T helper type 2 cytokine production in pollen antigen-stimulated CD4-positive cells

Co-stimulatory molecules are important for regulating T cell activation and immune response. CD274 [programmed death ligand 1 (PD-L1), B7-H1] has emerged as an important immune modulator that can block T cell receptor signalling. We have investigated whether PD-L1 and other co-stimulatory ligands could be expressed in human B cells stimulated by cytosine-phosphate-guanosine (CpG)-DNA. CpG-DNA strongly induced the co-inhibitory molecule ligand, PD-L1, of human B cells. Results show that nuclear factor-kappa B (NF-κB) signalling is involved directly in CpG-DNA-induced PD-L1 expression in human B cells. We sought to determine the effect of CpG-DNA-treated B cells on T helper type 2 (Th2) cytokine production in Cry j 1 (Japanese pollen antigen)-stimulated human CD4-positive cells from patients with seasonal allergic rhinitis caused by Japanese cedar pollen. CpG-DNA-treated B cells reduced Cry j 1-induced interleukin (IL)-5 and IL-13 production in CD4-positive cells. When the binding of PD-1 to PD-L1 was inhibited by PD-1-immunoglobulin (Ig), this chimera molecule reversed the previously described reductions in IL-5 and IL-13 production. In contrast, the CpG B-treated B cells increased both interferon (IFN)-γ and IL-12 production in the presence of Cry j 1-stimulated CD4-positive cells. CpG-DNA simultaneously reduced the expression of B7RP-1 [also known as inducible co-stimulator ligand (ICOSL), B7-H2] and the ligand of CD30 (CD30L). These results indicate that CpG-DNA induces co-inhibitory molecule ligand PD-L1 expression in human B cells and PD-L1 can suppress Th2 cytokine production in Cry j 1-stimulated CD4-positive cells, while CpG-DNA increased Th1 cytokine production and reduced the expression of co-stimulatory molecule ligands that can promote Th2 inflammatory responses.