Generation and characterization of a human iPSC line (JUFMDOi007-A) from a patient with Usher syndrome due to mutation in USH2A.

Usher syndrome type 2A (USH2A) gene mutations have been identified as the most frequent genetic causes of hereditary deafness in Usher syndrome, and an effective treatment has yet to be established. The encoded protein, Usherin, is essential for the ankle link associated with extracellular connections between the stereocilia of inner ear hair cells. We report the generation of a patient-derived USH2A iPSC line with compound mutations c.1907_1912ATGTTT > TCACAG (p.D636V + V637T + C638G) and c.8328_8329delAA (p.L2276fs*12). The iPSC showed the expression of pluripotency markers, the ability to differentiate into three germ layers in vitro, and USH2A mutations with normal karyotype.

Targeting Podoplanin for the Treatment of Osteosarcoma.

PURPOSE: Osteosarcoma, the most common bone malignancy in children, has a poor prognosis, especially when the tumor metastasizes to the lungs. Therefore, novel therapeutic strategies targeting both proliferation and metastasis of osteosarcoma are required. Podoplanin (PDPN) is expressed by various tumors and is associated with tumor-induced platelet activation via its interaction with C-type lectin-like receptor 2 (CLEC-2) on platelets. We previously found that PDPN contributed to osteosarcoma growth and metastasis through platelet activation; thus, in this study, we developed an anti-PDPN humanized antibody and evaluated its effect on osteosarcoma growth and metastasis. EXPERIMENTAL DESIGN: Nine osteosarcoma cell lines and two osteosarcoma patient-derived cells were collected, and we evaluated the efficacy of the anti-DPN-neutralizing antibody PG4D2 and the humanized anti-PDPN antibody AP201, which had IgG4 framework region. The antitumor and antimetastasis effect of PG4D2 and AP201 were examined in vitro and in vivo. In addition, growth signaling by the interaction between PDPN and CLEC-2 was analyzed using phospho-RTK (receptor tyrosine kinase) array, growth assay, or immunoblot analysis under the supression of RTKs by knockout and inhibitor treatment. RESULTS: We observed that PG4D2 treatment significantly suppressed tumor growth and pulmonary metastasis in osteosarcoma xenograft models highly expressing PDPN. The contribution of PDGFR activation by activated platelet releasates to osteosarcoma cell proliferation was confirmed, and the humanized antibody, AP201, suppressed in vivo osteosarcoma growth and metastasis without significant adverse events. CONCLUSIONS: Targeting PDPN with a neutralizing antibody against PDPN-CLEC-2 without antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity is a novel therapeutic strategy for PDPN-positive osteosarcoma.

Platelet-derived lysophosphatidic acid mediated LPAR1 activation as a therapeutic target for osteosarcoma metastasis.

Osteosarcoma is the most common primary malignant bone cancer, with high rates of pulmonary metastasis. Osteosarcoma patients with pulmonary metastasis have worse prognosis than those with localized disease, leading to dramatically reduced survival rates. Therefore, understanding the biological characteristics of metastatic osteosarcoma and the molecular mechanisms of invasion and metastasis of osteosarcoma cells will lead to the development of innovative therapeutic intervention for advanced osteosarcoma. Here, we identified that osteosarcoma cells commonly exhibit high platelet activation-inducing characteristics, and molecules released from activated platelets promote the invasiveness of osteosarcoma cells. Given that heat-denatured platelet releasate maintained the ability to promote osteosarcoma invasion, we focused on heat-tolerant molecules, such as lipid mediators in the platelet releasate. Osteosarcoma-induced platelet activation leads to abundant lysophosphatidic acid (LPA) release. Exposure to LPA or platelet releasate induced morphological changes and increased invasiveness of osteosarcoma cells. By analyzing publicly available transcriptome datasets and our in-house osteosarcoma patient-derived xenograft tumors, we found that LPA receptor 1 (LPAR1) is notably upregulated in osteosarcoma. LPAR1 gene KO in osteosarcoma cells abolished the platelet-mediated osteosarcoma invasion in vitro and the formation of early pulmonary metastatic foci in experimental pulmonary metastasis models. Of note, the pharmacological inhibition of LPAR1 by the orally available LPAR1 antagonist, ONO-7300243, prevented pulmonary metastasis of osteosarcoma in the mouse models. These results indicate that the LPA-LPAR1 axis is essential for the osteosarcoma invasion and metastasis, and targeting LPAR1 would be a promising therapeutic intervention for advanced osteosarcoma.

Novel knock-in mouse model for the evaluation of the therapeutic efficacy and toxicity of human podoplanin-targeting agents.

Podoplanin is a key molecule for enhancing tumor-induced platelet aggregation. Podoplanin interacts with CLEC-2 on platelets via PLatelet Aggregation-inducing domains (PLAGs). Among our generated antibodies, those targeting the fourth PLAG domain (PLAG4) strongly suppress podoplanin-CLEC-2 binding and podoplanin-expressing tumor growth and metastasis. We previously performed a single-dose toxicity study of PLAG4-targeting anti-podoplanin-neutralizing antibodies and found no acute toxicity in cynomolgus monkeys. To confirm the therapeutic efficacy and toxicity of podoplanin-targeting antibodies, a syngeneic mouse model that enables repeated dose toxicity tests is needed. Replacement of mouse PLAG1-PLAG4 domains with human homologous domains drastically decreased the platelet-aggregating activity. Therefore, we searched the critical domain of the platelet-aggregating activity in mouse podoplanin and found that the mouse PLAG4 domain played a critical role in platelet aggregation, similar to the human PLAG4 domain. Human/mouse chimeric podoplanin, in which a limited region containing mouse PLAG4 was replaced with human homologous region, exhibited a similar platelet-aggregating activity to wild-type mouse podoplanin. Thus, we generated knock-in mice with human/mouse chimeric podoplanin expression (PdpnKI/KI mice). Our previously established PLAG4-targeting antibodies could suppress human/mouse chimeric podoplanin-mediated platelet aggregation and tumor growth in PdpnKI/KI mice. Repeated treatment of PdpnKI/KI mice with antibody-dependent cell-mediated cytotoxicity activity-possessing PG4D2 antibody did not result in toxicity or changes in hematological and biochemical parameters. Our results suggest that anti-podoplanin-neutralizing antibodies could be used safely as novel anti-tumor agents. Our generated PdpnKI/KI mice are useful for investigating the efficacy and toxicity of human podoplanin-targeting drugs.

A genetic typing method for albino mutation in the Mongolian gerbil by PCR-RFLP analysis.

1. We established a PCR-RFLP analysis targeting R77H mutation in the Tyr gene as a more effective genotyping to identify carrier (C/c) with the albino allele and the agouti phenotypes. 2. Our breeding system, which targets the R77H site, is a useful cue for detecting C/c carriers with the agouti-phenotype and helps us to obtain albinos by mating agouti-phenotype carriers.

A safety study of newly generated anti-podoplanin-neutralizing antibody in cynomolgus monkey (Macaca fascicularis).

Hematogenous metastases are enhanced by platelet aggregation induced by tumor cell-platelet interaction. Podoplanin is a key molecule to enhance the platelet aggregation and interacts with C-type lectin-like receptor 2 (CLEC-2) on platelet via PLAG domains. Our previous reports have shown that blocking podoplanin binding to platelets by neutralizing antibody specific to PLAG4 domain strongly reduces hematogenous metastasis. However, podoplanin is expressed in a variety of normal tissues such as lymphatic vessels and the question remains whether treatment of tumors with anti-podoplanin neutralizing antibodies would be toxic. Monkeys are the most suitable species for that purpose. PLAG3 and PLAG4 domains had high homology among various monkey species and human. PLAG domain deleted mutants were indicated that monkey PLAG4 domain played a more crucial role in podoplanin-induced platelet aggregation than did the PLAG3 domain as in human. Moreover, newly established neutralizing antibodies (1F6, 2F7, and 3F4) targeting the monkey PLAG4 domain blocked interaction between monkey podoplanin and CLEC-2. Especially, the 2F7 neutralizing antibody strongly suppressed platelet aggregation and pulmonary metastasis. Furthermore, inhibiting podoplanin function with 2F7 neutralizing antibody exhibited no acute toxicity in cynomolgus monkeys. Our results suggested that targeting podoplanin with specific neutralizing antibodies may be an effective anticancer treatment.

Conditioned medium from gerbil--mouse T cell heterohybridomas improved antibody secretion.

Mongolian gerbils (Meriones unguiculatus) are widely used as animal models for a variety of infectious diseases. However, immunological reagents such as cytokines have not been characterized. Two heterohybridomas, D9(E6)C2B3 and D9(E4), obtained by fusion of gerbil splenocytes with mouse myeloma cells (P3-X63-Ag8.653), expressed gerbil CD3G mRNA. These cells were suggested to be T cell heterohybridomas. They also expressed gerbil IL6 [D9(E6)C2B3] and TGFB [D9(E4) and D9(E6)C2B3] mRNAs. The addition of conditioned medium (CM) obtained from the culture of D9(E6)C2B3 significantly enhanced antibody secretion and expression of gerbil Cγ1 and Cε IGHC mRNAs in the B11D2(C2) heterohybridoma, which secretes gerbil IgG1. However, the addition of CM from both heterohybridomas did not improve in proliferation of B11D2(C2) cells. These results indicate that CM from D9(E6)C2B3 improved the culture of gerbil-mouse heterohybridomas, possibly by secreting gerbil IL6.

Use of genomic in situ hybridization to identify chromosomes in gerbil-mouse heterohybridomas.

Heterohybridomas, created to secrete monoclonal antibodies, are generally unstable over long-term culture because of chromosome elimination during culture. To evaluate the karyotype of heterohybridomas, we used simultaneous genomic in situ hybridization (GISH), which can distinguish unambiguously between parental genomes in allopolyploid species. Using GISH, we discriminated gerbil and mouse chromosomes in heterohybridomas with high sensitivity. The GISH technique will allow evaluation of the stability and crossability of heterohybridomas made from the fusion of mouse cells with those of related species.

Isotype analysis of gerbil-mouse heterohybridomas by RT-PCR.

We designed primer sets specific to the immunoglobulin (Ig) heavy-chain constant region (IGHC) genes in Mongolian gerbil (Meriones unguiculatus) to amplify five gerbil IGHC cDNA sequences, Cµ, Cγ1, Cγ2, Cε, and Cα. Five gerbil-mouse heterohybridomas B11D2(C2), B11E2(D5).M, B5-3, D5, and C11 respectively expressed Cγ1, Cµ, Cγ2, Cγ2, and Cγ1. In contrast, a commercial isotyping kit for mouse Igs identified Cγ1, Cµ, Cγ3, Cγ3, and Cγ1, respectively, misidentifying gerbil IgG2 as IgG3 by cross-reactivity with anti-mouse IgG3 polyclonal antibody. These primer sets will allow the accurate estimation of gerbil Ig classes and IgG subclasses. These results from three gerbil strains indicate that the primer sets can be used for isotype analysis of gerbil mAbs and for evaluation of humoral immunity.

Sequence determination of the heavy-chain constant region in four immunoglobulin classes of Mongolian gerbils (Meriones unguiculatus).

We determined partial cDNA sequences of four immunoglobulin (Ig) classes-IgM, IgG1, IgE, and IgA-of Mongolian gerbil (Meriones unguiculatus). Each deduced Ig heavy-chain constant (IGHC) region-Cµ, Cγ1, Cε, and Cα-is structurally similar to its counterparts in the mouse and rat, and phylogenetic analysis suggests that the gerbil Igs are evolutionarily close to their counterparts. In spite of the high sequence homology to the other rodent Cγ sequences, the gerbil Cγ1 sequence differs from our previously reported Cγ2. This result indicates that the gerbil has at least two IgG subclasses. These four gerbil IGHC cDNA sequences will be useful for determining gerbil Ig isotypes and examining the expression of gerbil Ig mRNAs in response to parasitic and bacterial infections.

Establishment of gerbil-mouse heterohybridoma secreting immunoglobulin of Mongolian gerbil (Meriones unguiculatus) establishment of gerbil-mouse heterohybridoma.

Hybridomas, generated by fusing myeloma cells with B lymphocytes, secrete monoclonal antibodies (mAbs) specific for an antigen. To establish hybridomas that secrete Mongolian gerbil (Meriones unguiculatus) mAbs, we immunized gerbils with keyhole limpet hemocyanin (KLH) and fused splenocytes from them with a non-secreting mouse myeloma cell line (P3-X63-Ag8.653). We obtained hybridomas that secreted immunoglobulin (Ig) against KLH. These hybridomas had more chromosomes than either parent and retained several gerbil chromosomes. Therefore, these cells were heterohybridomas with both gerbil and mouse chromosomes. They expressed gerbil Ig heavy-chain constant (IGHC) region mRNA, but not mouse gamma (γ) 1 IGHC. SDS-PAGE and Western blot analyses indicated that the cells secreted whole Ig molecules of gerbil origin. Moreover, the cells continued secreting Ig for several months.

Partial sequence of Mongolian gerbil (Meriones unguiculatus) immunoglobulin gamma heavy chain constant region.

We determined the sequence of the immunoglobulin gamma heavy-chain constant (IGHC) region of the Mongolian gerbil (Meriones unguiculatus). To isolate a part of the IGHC complementary DNA, we designed primers on the basis of highly conserved sequences in mouse, rat and hamster. The deduced IGHC is structurally similar to counterparts in other mammalian species and shows 84.6% identity to the IGHC of hamster IgG, 76.6% to rat IgG1, 83.3% to rat IgG2a, 78.1% to mouse IgG1, 81.8% to mouse IgG2a, 79.1% to mouse IgG2b and 79.2% to mouse IgG3 at the nucleotide level. The results suggest that gerbil IgG is closely related to hamster IgG and rat IgG2a.