Positive Raji Research Articles

Evaluation of CD70 Chimeric Antigen Receptor T (CAR-T) Cells As a Potential Treatment for Non-Hodgkin's Lymphoma: A Preclinical Study

Background ：CD70 is a member of the tumor necrosis factor (TNF) superfamily. While its expression is limited in healthy tissues, CD70 highly constitutive expressed on cell surface of various malignancies. This expression profile make CD70 a promising target for cancer immunotherapy. We described a CD70 CAR-T based on a potent VHH nanobody named 11C9 in treatment of renal cell carcinoma (RCC). Recently, we received approval to initiate a phase I clinical study by Center for Drug Evaluation, National Medical Products Administration (NMPA) in China. Motivated by promising evidence that CD70 aberrantly expressed on Non-Hodgkin's lymphoma (NHL), including diffuse large B-cell lymphomas, follicular lymphomas, Burkitt and mantle cell lymphomas, we conducted a preclinical evaluation of CD70 CAR-T cells as a potential treatment by preclinical model. Method: We successfully generated CD70 CAR-T cells based on a VHH nanobody (11C9) and CD19 CAR-T cells based on murine scFv (FMC63) following the exact manufacturing protocols used for phase I and phase II clinical trial products respectively. Then, we evaluated CAR-T cell cytotoxicity, phenotype, proliferation, and cytokine production in vitro. Furthermore, we established NHL tumor cell-xenograft NOG mice models to compare their anti-tumor activity in vivo. Result: In vitro test demonstrated two types of CAR-T cells have comparable proliferation, and cytokine production. We observed more potency for CD70 CAR-T to kill CD70 and CD19 double positive Raji cells than CD19 CAR-T cells. In vivo test showed that both CD70 CAR-T cells and CD19 CAR-T cells eradiated Raji cells xenografted NOG mice models at high dose. However, after treated at lower dose CD19 CAR-T, tumor relapsed in one week when the same lower dose CD70 CAR-T treated mice keeping tumor free statue. Conclusion: Our results indicate that CD70 CAR-T cell is potential treatment for NHL. We will conduct an investigation of single and dual CD70 CAR-T on treatment of lymphoma especially for CD19 negative NHL.

CD19-CAR Cytokine Induced Killer Cells Armored with IL-18 Control Tumor Burden, Prolong Mouse Survival and Result in In Vivo Persistence of CAR-CIK Cells in a Model of B-Cell Acute Lymphoblastic Leukemia

Rationale: Cytokine induced killer cells (CIK) are a promising cancer immunotherapy. Recently CIK cells modified to express chimeric antigen receptors (CAR) target CD19 expressing hematological malignancies including B-cell acute lymphoblastic leukemia (B-ALL). Despite encouraging clinical trial results, insufficient CAR-CIK anti-tumor activity and persistence pose major obstacles towards improved efficacy in vivo. Therefore, we optimized our CAR-CIK platform by introducing two modifications to the CD19-CAR construct. The first modification “armored” CAR-CIK cells by inserting the IL-18 gene in a bicistronic DNA plasmid enabling simultaneous surface expression of the CAR protein and secretion of IL-18, which demonstrated improved CAR-T cell function. The second modification attenuated the CD28 cytoplasmic signaling domain of the CAR molecule to enhance anti-tumor activity and in vivo persistence since recent findings demonstrate that persistent or chronic CAR signaling can impair anti-tumor activity and in vivo persistence. Methods: CARCIK-1918 cells generated from donor-derived CIK cells are engineered to express CAR and IL-18 using the non-viral Sleeping Beauty (SB) transposon system. CIK cells were generated from donor PBMCs by the sequential addition of IFN-ϒ and stimulation with anti-CD3 antibody plus IL-2. After 2 days of stimulation CIK cells were co-electroporated with SB100X transposase mRNA and plasmid DNA containing a bicistronic transgene encoding both the anti-CD19 CAR and IL-18. This second-generation CAR contains a fusion of the CD28 transmembrane domain, intracellular CD28 and, TCR CD3ζ chain. In some instances, the cytoplasmic CD28 signaling domain is modified to attenuate CD28 signaling. This method of gene transfer results in stable surface expression of the CAR on CD3+ cells through a 17-day culture period. Day 17 cells are harvested, frozen and used for all subsequent studies. CARCIK-1918 cells are stimulated in vitro with CD19+ REH tumor cells and the phenotype of activated cells was characterized by multi-color flow cytometry. IL-18 secretion was determined by cytokine bead array analysis of supernatants collected post stimulation. CARCIK-1918 cells with or without the attenuated CD28 signaling domain were tested in vivo in a xenograft model of B-ALL, using NSG mice engrafted with CD19+ Raji tumor cells. Tumor burden was assessed weekly by bioluminescence imaging, the in vivo persistence of CARCIK-1918 cells was measured by flow cytometry, and survival was monitored throughout the study. Results: CARCIK-1918 cells express both IL-18 and CAR with or without attenuated CD28 signaling. Furthermore, stimulation of CARCIK-1918 cells with CD19+ REH tumor cells increases the frequency of CAR-CIK cells with a memory phenotype and concurrent upregulation of the high affinity IL-2 receptor, CD25, and the costimulatory receptor CD137. Expression of IL-18 leads to higher engraftment of CAR-CIK cells in tumor bearing NSG mice compared to unarmored controls. NSG mice engrafted with luciferase positive Raji cells demonstrated decreased bioluminescent signal following CARCIK-1918 treatment, consistent with CARCIK derived anti-leukemic activity. This anti-tumor activity corresponded to a statistically significant improvement in survival as mice treated with 2 nd generation CAR transgene CARCIK cells with or without attenuated CD28 signaling had a median survival of 37.5 (n=10; p=0.0001) and 38 (n=12; p =0.0001 days), respectively, compared to untreated mice that develop progressive highly disseminated tumor and succumb to disease by 3 weeks post tumor inoculation (n=11; median survival 18 days). Interestingly, mice treated with CARCIK-1918 cells with the CD28 attenuated signaling domain exhibited better tumor control and enhanced persistence in vivo, despite no significant improvement in survival compared to WT CD28 signaling CARCIK-1918 cells. Summary: This study demonstrates that administration of CAR-CIK cells armored with IL-18 results in a significant survival advantage for tumor challenged animals versus untreated animals. Furthermore, modifying the cytoplasmic CD28 domain to attenuate signaling, results in better control of tumor burden, and persistence of CARCIK-1918 cells in vivo. Our study is the first report of IL-18 armored CAR-CIK cells which may present a promising, novel strategy for the treatment of B-ALL.

Nicotinamide adenine dinucleotide phosphate oxidase inhibitor induces apoptosis on Epstein-Barr virus positive B lymphoma cells.

Over-expression of nicotinamide adenine dinucleotide phosphate oxidase (Nox) isoform enzymes was recently reported in various cancers including Burkitt’s lymphoma (BL). However, the functions of Nox isoform enzymes in BL remain poorly understood. In this study, Nox isoform expression and the effects of a Nox-specific inhibitor were evaluated in Epstein-Barr virus (EBV)-positive Raji BL cells in comparison with EBV-negative Ramos BL cells. To evaluate Nox enzyme expression in Raji and Ramos BL cells, polymerase chain reaction (PCR) and western blot analysis were performed. To verify the intracellular signaling mechanism of the Nox inhibitor-induced apoptosis of Raji cells, WST-1 assay, trypan blue exclusion method, flow cytometry, PCR, western blotting, and bromodeoxyuridine staining were conducted. Experiments using the pan-caspase inhibitor z-VAD, reactive oxygen species scavenger N-acetyl-L-cysteine (NAC), and Bim inhibitor 1 were performed. PCR and western blot results showed that Nox isoform enzymes were highly expressed in EBV-positive BL Raji cells compared with EBV-negative BL Ramos cells. The Nox2 inhibitor induced apoptosis of Raji cells in time- and dose-dependent manners. The Nox2 inhibitor also caused up-regulation of Bim and Noxa, down-regulation of Mcl-1, translocation of Bax, release of cytochrome c, and caspase cascade activation, resulting in apoptosis. Furthermore, z-VAD, NAC, and BI-1 effectively blocked the Nox2 inhibitor-induced apoptosis of Raji cells. Taken together, these results provide a novel insight into the mechanism of Nox inhibitor-induced apoptosis and evidence for Nox as a therapeutic target to treat EBV-positive malignancies.

Construction of a novel lentiviral vector knocking down PD-1 via microRNA and its application in CAR-T cells

By inserting microRNAs into the intron of EF1α promoter, we constructed a novel lentiviral vector knocking down PD-1 gene via microRNA and applied it to CAR-T cells. Lentiviral transduction efficiency and PD-1-silencing efficiency were detected by flow cytometry. PD-1 expression was detected by Western blotting. Relative expression of microRNA was measured by Q-PCR. Cytotoxicity of CAR-T cells based on this vector was tested by luciferase bioluminescence and flow cytometry. Compared with lentiviral vector with microRNA transcribed by U6 promotor, the transduction efficiency of lentiviral vector with microRNA which was inserted into the intron of EF1α promoter was more significant, and the knockdown rate of PD-1 was more than 90%, which was validated by flow cytometry and Western blotting. And the relative expression level of microRNA in Jurkat cells transduced with this novel lentiviral vector was shown by Q-PCR. Compared with normal CAR-T cells, CAR-T cells based on this vector showed stronger cytotoxicity against PD-L1 positive Raji cells. We successfully constructed a novel lentiviral vector that knocked down PD-1 via microRNA and verified the superiority of its transduction efficiency and knockdown efficiency of PD-1. CAR-T cells based on this vector can exert a more powerful cytotoxicity, thus providing theoretical support for the subsequent treatment of PD-L1 positive tumors.

Catfish egg lectin affects influx and efflux rates of sunitinib in human cervical carcinoma HeLa cells.

New treatment protocols are aiming to reduce the dose of the multitargeted tyrosine kinase inhibitor sunitinib, as sunitinib elicits many adverse effects depending on its dosage. Silurus asotus egg lectin (SAL) has been reported to enhance the incorporation of propidium iodide as well as doxorubicin into Burkitt's lymphoma Raji cells through binding to globotriaosylceramide (Gb3) on the cell surface. The objective of this study was to examine whether SAL enhances the cytotoxic effect of sunitinib in Gb3-expressing HeLa cells. Although the treatment with SAL delayed the cell growth and enhanced the propidium iodide uptake, cell death accompanied by membrane collapse was not observed. The viability of sunitinib-treated HeLa cells was significantly reduced when the treatment occurred in combination with SAL compared to their separate usage. Sunitinib uptake significantly increased for 30min in SAL-treated cells, and this increment was almost completely abolished by the addition of L-rhamnose, a hapten sugar of SAL, but not by D-glucose. After removal of SU from the medium, the intracellular sunitinib level in SAL-treated cells was higher than in untreated cells for 24h, which was not observed in Gb3-deficient HeLa cells. Furthermore, we observed that SAL promoted the formation of lysosome-like structures, which are LAMP1 positive but not acidic in HeLa cells, which can trap sunitinib. Interestingly, SAL-induced vacuolation in HeLa cells was not observed in another Gb3 positive Raji cells. Our findings suggest that SAL/Gb3 interaction promoted sunitinib uptake and suppressed sunitinib excretion and that sunitinib efficiently exerted cytotoxicity against HeLa cells.

A novel anti-CD22 scFv\u2013apoptin fusion protein induces apoptosis in malignant B-cells

CD22 marker is a highly internalizing antigen which is located on the surface of B-cells and is being used as a promising target for treatment of B cell malignancies. Monoclonal antibodies targeting CD22 have been introduced and some are currently under investigation in clinical trials. Building on the success of antibody drug conjugates, we developed a fusion protein consisting of a novel anti-CD22 scFv and apoptin and tested binding and therapeutic effects in lymphoma cells. The recombinant protein was expressed in E. coli and successfully purified and refolded. In vitro binding analysis by immunofluorescence and flow cytometry demonstrated that the recombinant protein specifically binds to CD22 positive Raji cells but not to CD22 negative Jurkat cells. The cytotoxic properties of scFv–apoptin were assessed by an MTT assay and Annexin V/PI flow cytometry analysis and showed that the recombinant protein induced apoptosis preferentially in Raji cells with no detectable effects in Jurkat cells. Our findings indicated that the recombinant anti-CD22 scFv–apoptin fusion protein could successfully cross the cell membrane and induce apoptosis with high specificity, make it as a promising molecule for immunotherapy of B-cell malignancies.

Intracellular pH-responsive and rituximab-conjugated mesoporous silica nanoparticles for targeted drug delivery to lymphoma B cells

BackgroundOne of the main problems in B cell lymphoma treatment is severe adverse effects and low therapeutic efficacy resulting from systemic chemotherapy. A pH-sensitive controlled drug release system based on mesoporous silica nanoparticles was constructed for targeted drug delivery to tumor cells to reduce systemic toxicity and improve the therapeutic efficacy.MethodsIn this study, the doxorubicin (DOX) was filled into the mesopores of the functional MSNs (DMSNs). Furthermore, rituximab was introduced as the targeted motif of functional DMSNs using an avidin-biotin bridging method to evaluate the targetability to tumor cells. Then, the cell viability and apoptosis efficiency after treatment with rituximab-conjugated DMSNs (RDMSNs) were estimated by using CCK-8 assay and flow cytometry, respectively. Additionally, the research in vivo was performed to evaluate the enhanced antitumor efficacy and the minimal toxic side effects of RDMSNs. Also, TUNEL staining assay was employed to explore the mechanism of antitumor effects of RDMSNs.ResultsThis targeted drug delivery system exhibited low premature drug release at a physiological pH and efficient pH-responsive intracellular release under weakly acidic conditions. The in vitro tests confirmed that targeted RDMSNs could selectively adhere to the surface of lymphoma B cells via specific binding with the CD20 antigen and be internalized into CD20 positive Raji cells but few CD20 negative Jurkat cells, which leads to increased cytotoxicity and apoptosis of the DOX in Raji cells due to the release of the entrapped DOX with high efficiency in the slightly acidic intracellular microenvironment. Furthermore, the in vivo investigations confirmed that RDMSNs could efficiently deliver DOX to lymphoma B cells by pH stimuli, thus inducing cell apoptosis and inhibiting tumor growth, while with minimal toxic side effects.ConclusionsThis targeted and pH-sensitive controlled drug delivery system has the potential for promising application to enhance the therapeutic index and reduce the side effects of B cell lymphoma therapy.

The Roles of Aryl Hydrocarbon Receptor in T Cells at IDO-Positive Tumor Microenvironment

Introduction:Aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor well known to generate biological responses to dioxins. A recent study indicated that kynurenine was an endogenous ligand of AhR and was associated with suppression of the antitumor response. The essential amino acid tryptophan metabolism proceeds via the enzymes IDO, which generates the immunosuppressive metabolites, such as kynurenine. Accumulation of these tryptophan derivatives block antigen-specific T-cell proliferation and induces T-cell death through the AhR. IDO is known to be produced by tumor cells and by some immune cells, such as dendritic cells and macrophages, which reside in tumor-draining lymph nodes or are recruited to tumors. IDO is overexpressed in several human cancers, including prostate, breast, brain, and hematologic malignancies.We previously showed that both IDO expression by tumor cells and high serum kynurenine levels correlate with poor prognosis in non-Hodgkin lymphoma patients. We also revealed that tumor IDO activity can inhibit CD19-specific chimeric antigen-receptor (CAR) T-cells (CARTs) therapy through the action of tryptophan metabolites (Blood. 2015; 125(25): 3905-3916). Therefore, we focused on the AhR in T-cells at IDO-positive tumor microenvironment.Methods and Results:We collected PBMCs from healthy blood donors, and activated the cells with anti-CD3 and anti-CD28 Abs, which mimic physiological T-cell activation. We measured the expression of AhR in activated T-cells using by flow cytometry, and found that the range of expression were from 4.5% to 38%. We then studied the effect of kynurenine on the proliferation of T-cells. The proliferation was assessed by MTS assay. We found that kynurenine significantly inhibited the proliferation of T-cells with high expression of AhR. The percentage inhibition with kynurenine 25µM was 33%. While T-cells with low expression of AhR were not inhibited with even 50µM of kynurenine. To investigate potential mechanisms of T-cell inhibition by kynurenine, we assessed the effect of kynurenine on T-cell apoptosis. We found that kynurenine was also associated with increased the apoptosis of T-cells with high AhR, as assessed by Annexin-V staining (percent Annexin-V positive and 7-AAD negative cells in 0 and 25 µM kynurenine was 11.8% and 36%, respectively). To evaluate the effect of inhibiting AhR in T-cells, we used AhR inhibitor (CH-223191). We found that CH-223191 could blocked the inhibitory effects of kynurenine on T-cells. The percent Annexin-V positive and 7-AAD negative cells in 25 µM kynurenine plus CH-223191 was 22.5%. Next, to assess the functional effects of tryptophan metabolites on the T-cells, we cocultured T-cells (1x106) with GFP-transduced wild-type Raji cells or IDO-transduced Raji cells (1x106). After 72 hours, cells were stained with CD8 antibody to distinguish tumor (GFP+ CD8-) and T-cells (GFP- CD8+). We found that the percentage of T-cells with high AhR in culture with IDO negative and positive Raji cells was 46.7% and 61.4%, respectively, while the percentage of T-cells with low AhR was 41.6% and 39.4%. These data showed that only T-cells with high AhR were inhibited at IDO-positive tumor microenvironment. Next, bone marrow (BM) samples were obtained from multiple myeloma (MM) patients at diagnosis. We could generated the activated T-cells from 10 of 12 BM samples. The expression of AhR in T-cells was ranged from 3.3% to 26.6%. We found that there was a positive correlation between the expression of AhR and the proportion of plasma cells in BM (r=0.76, P=0.04).Discussion:The expression of AhR in activated T cells play an important role in the effect of kynurenine, which is a metabolite produced by IDO. A few clinical trials are evaluating the effects of IDO inhibitors that competitively block the degradation of tryptophan to kynurenine by the enzyme. Because anti-PD-1 and anti-CTLA-4 therapies, which block directly the inhibitory signal in T-cells, have been getting some clinical benefits against such as melanoma and Hodgkin lymphoma. Therefore, AhR in T cells might be a target for IDO-positive hematological malignancies. DisclosuresNo relevant conflicts of interest to declare.

Effects of mTOR and calcineurin inhibitors combined therapy in Epstein–Barr virus positive and negative Burkitt lymphoma cells

Post-transplant lymphoproliferative disorder is a severe complication in solid organ transplant recipients, which is highly associated with Epstein–Barr virus infection in pediatric patients and occasionally presents as Burkitt- or Burkitt-like lymphoma. The mammalian target of rapamycin (mTOR) pathway has been described as a possible antitumor target whose inhibition may influence lymphoma development and proliferation after pediatric transplantation. We treated Epstein–Barr virus positive (Raji and Daudi) and negative (Ramos) human Burkitt lymphoma derived cells with mTOR inhibitor everolimus alone and in combination with clinically relevant immunosuppressive calcineurin inhibitors (tacrolimus or cyclosporin A). Cell proliferation, toxicity, and mitochondrial metabolic activity were analyzed. The effect on mTOR Complex 1 downstream targets p70 S6 kinase, eukaryotic initiation factor 4G, and S6 ribosomal protein activation was also investigated. We observed that treatment with everolimus alone significantly decreased Burkitt lymphoma cell proliferation and mitochondrial metabolic activity. Everolimus in combination with cyclosporin A had a stronger suppressive effect in Epstein–Barr virus negative but not in Epstein–Barr virus positive cells. In contrast, tacrolimus completely abolished the everolimus-mediated suppressive effects. Moreover, we showed a significant decrease in activation of mTOR Complex 1 downstream targets after treatment with everolimus that was attenuated when combined with tacrolimus, but not with cyclosporin A. For the first time we showed the competitive effect between everolimus and tacrolimus when used as combination therapy on Burkitt lymphoma derived cells. Thus, according to our in vitro data, the combination of calcineurin inhibitor cyclosporin A with everolimus is preferred to the combination of tacrolimus and everolimus.

Engineering of CD19-CAR T Cells from Non-Hodgkin Lymphoma Patients in a Closed System in Combination with Retronectin/OKT3 Stimulation

Background; Adoptive immunotherapy with chimeric antigen receptor (CAR) gene transduced CD19-CAR T cells, which are engineered to express extracellular single-chain immunoglobulin variable fragments to CD19, linked to cytoplasmic T cell activation domains including CD3-ζ, showed remarkable therapeutic benefits toward CD19+ B cell malignancies including acute lymphoblastic leukemia, chronic lymphoblastic leukemia and non-Hodgkin lymphoma (B-NHL). For clinical setting, the phenotype of manufactured CAR T cells is an important factor; especially less differentiated T cells are anticipated to provide a long-lasting immune reconstitution. Furthermore, in order to avoid the risk of technical error and contamination during T cell manufacturing process, a closed system needs to be established. In this study, we addressed these issues and have established a novel CD19-CAR T cell manufacturing method from a small amount of blood in a closed system for clinical trial to treat patients with B-NHL.Methods; Peripheral blood was obtained from B-NHL patient volunteers and healthy donor volunteers who gave their written informed consents. Peripheral blood mononuclear cells (PBMCs) were isolated from 30 ml of blood using Ficoll-Paque PREMIUM density gradient centrifugation. PBMCs were stimulated in a plastic bag pre-coated with anti-CD3 monoclonal antibody (OKT3) and recombinant fibronectin fragment (RetroNectin®; RN). Following four days of stimulation, stimulated T cells were transferred into a 215 cm2 plastic bag pre-loaded with SFG-1928z retroviral vector (Brentjens et al., Clin Cancer Res. 2007) onto RN-coated substratum with low-temperature shaking (RBV-LTS method; Dodo et al., PLoS ONE, 2014). After one hour incubation, the bag was flipped over to facilitate more efficient utilization of the retroviral vector adsorbed on both top and bottom surfaces of the bag and further incubated. On Day 5, the transduction procedure was repeated, and the cells were transferred into 640 cm2 plastic bags until Day 10-14 for expansion. Closed system liquid handling was managed in all processes of manipulating T cells for stimulation, transduction, expansion and final product formulation.Results; We have previously reported that the fold expansion of T cells under stimulation with RN together with OKT3 enhanced cell proliferation while preserving the naïve phenotype of T cells in comparison to stimulation with OKT3 alone or OKT3 and anti-CD28 monoclonal antibody co-stimulation. Although B-NHL patients’ T cells showed much lower fold expansion compared to healthy donors’ T cells, 4/7 patients’ CAR T cells reached their target dose of 1 x 106 cells/kg from 30 ml of blood on Day 10. For the other 3 patients, 70-150 ml blood was estimated to be required to reach their target dose. The delay in proliferations was marked in B-NHL patients’ T cells compared to healthy donors’ T cells by Day 5, but B-NHL patients’ T cells represented significant catch-up growth, which was superior to healthy donor T cells during Day 7-14. Gene transfer efficiency of patients’ T cells (N = 7, 17.9 ± 4.7%) was equivalent to that of healthy donors’ T cells (N = 5, 22.2 ± 5.3%), and CAR T cells showed potent anti-tumor reactivity with cytokine productions against CD19 positive Raji cells in vitro. Comparing to CD3/CD28 beads stimulation method, RN/OKT3 stimulation method showed equivalent expansion. Furthermore, RN/OKT3 stimulated T cells preserved higher proportion of CD8+/CCR7+/CD45RA+/CD62L+ naïve phenotype T cells (43.6% in healthy donor and 30.9% in patient donor) compared to CD3/CD28 beads stimulated T cells (22.8% in healthy donor and 11.7% in patient donor).Conclusions; With our novel closed system manufacturing method utilizing RN/OKT3 stimulation combined with RBV-LTS transduction from a small amount of blood of B-NHL patients, we are able to manufacture a sufficient number of CAR T cells maintaining higher proportion of naïve phenotype, which is expected to improve the efficacy of adoptive immunotherapy. In our cell manufacturing, patients are not required to undergo leukapheresis, which is more invasive to patients. Based on our results, we employed our novel manufacturing method for the phase I/II clinical trial to treat patients with relapsed/refractory CD19+ B-NHL (clinicaltrials.gov, identifier; NCT02134262). DisclosuresChono:Takara Bio Inc.: Employment. Tahara:Takara Bio Inc.: Employment. Nukaya:Takara Bio Inc.: Employment. Mineno:Takara Bio Inc.: Membership on an entity’s Board of Directors or advisory committees. Tsukahara:Takara Bio Inc.: Research Funding. Ohmine:Takara Bio Inc.: Research Funding. Ozawa:Takara Bio Inc.: Research Funding. Takesako:Takara Bio Inc.: Membership on an entity’s Board of Directors or advisory committees.

Inhibitory effect of genistein on the proliferation of Raji cells and its related mechanism

This study was aimed to investigate the anti-proliferative effect of genistein (Gen) on BCL-6 positive Raji cells and its related mechanism. Trypan blue staining and MTT method were used to analyze the anti-proliferative effect of Gen on Raji cells. Cell apoptosis, protein expression and the interaction of BCL-6 and NCoR were detected by PI/AV dual staining, Western blot and Co-IP method, respectively. The results showed that Gen had time- and dose-dependent inhibitory effect on Raji cell proliferation and induced apoptosis. Different dose of Gen had no significant effect on the expression of BCL-6 and NCoR, but could inhibit the binding of BCL-6 and NCoR. It is concluded that Gen shows inhibitory effect on BCL-6 positive lymphoma cells, which can be as a adjuvant therapy for combined rituximab with chemotherapy.

Study of RON mediated invasion of Raji cell line and drug-target effects

To study the proto-oncogene RON mediated aggression of Raji cells and the inhibitory effects by monoclonal antibody Zt/f2 (2f2). The effects of RON ligand macrophage stimulating protein (MSP) (2.0 nmol/L) and inhibitory Zt/f2 (2F2) (2.0 nmol/L) antibody on proliferation of RON positive Raji cells after treatment for 24 and72 hours were detected by MTT method, colony formation units (CFU) of Raji cells by methylcellulose semi solid culture, Raji cells apoptosis and cell cycle analysis by AnnexinV/PI double staining, expression of RON, apoptosis-related proteins, and cyclins by Western blot. (1)Compared with the cell viability (1.0) and counts of CFU (103.6±7.0) in control group, Raji cells after MSP treatment had better viability (1.35±0.20) and CFU counts (133.7±10.4) (P<0.05), but worse viability (0.68±0.11) and CFU counts (66.3±6.1) after Zt/f2 (2F2) treatment (P<0.05). (2)Percentage of Raji cells apoptosis after Zt/f2 (2F2) antibody treatment (12.16±2.33)% was significantly increased than the control (2.89±1.03)% (P<0.05). The percentage of Raji cells arrested in G0/G1 phase was increased after Zt/f2 (2F2) antibody treatment as compared to the control [ (54.96 ±3.70)% vs (39.10±2.30)%, (P<0.05) ]. (3) High-level of RON phosphorylation and β-catenin expression activated by MSP could be inhibited significantly by Zt/f2 (2F2), which also up-regulated the expression of caspase-3, caspase-8, caspase-9 and PARP and down-regulated anti-apoptotic MCL-1 gene and inhibitor of apoptosis protein XIAP expression, accompanied with G1 phase protein changes accordingly. MSP could aggravate Raji cells proliferation. Inversely, Zt/f2 (2F2) could inhibit proliferation and induce apoptosis by inhibition of RON phosphorylation and up-regulation of apoptosis related proteins.

Abstract 5477: Engineered toxin body demonstrating CD20-specific binding and cell kill in B-cell non-Hodgkin's lymphoma cells.

Abstract Non-Hodgkin's lymphoma (NHL) offers an attractive area for therapeutic biologics. The most successful example of this targeted approach is rituximab, which is approved for front and second line therapy of NHL. Rituximab targets the CD20 antigen expressed on 90% of B-cell NHL cells. However, rituximab has limited direct cell-kill effects, acting instead primarily through indirect immune responses induced by antibody-dependent cell-mediated cytotoxicity (ADCC) and/or complement dependent cytotoxicity (CDC). Direct-cell kill approaches to CD20 have been limited to radioimmunotherapy because CD20 does not efficiently internalize. Despite improved clinical efficacy seen over Rituximab with both 131 tositumomab and ibritumomab tiuxetan, challenges around the administration of radioimmunotherapies have severely curtailed therapeutic use. We have developed an engineered toxin body (ETB) comprising a CD20 scFv and a modified Shiga-like Toxin A (3F7) capable of specifically recognizing and killing CD20 expressing cells. Utilizing a flow cytometry based binding affinity assay, 3F7 demonstrated selective binding to CD20 positive Raji cells whereas no significant binding was observed in CD20 negative BC-1 cells. Further, direct competition of 3F7 binding to Raji cells was observed in the presence of rituximab or the parent monoclonal antibody. 3F7 demonstrated CD20-specific direct cell kill of Raji, Daudi and Ramos cells with minimal cell kill of CD20 negative BC-1 or Jurkat cells. Initial dose finding studies in mice found that a therapeutic dosing schedule was well tolerated. Raji xenograft studies in mice are ongoing. 3F7 is a novel therapeutic approach with direct cell-kill activity against CD20-expressing cells which could expand treatment options for B-cell lymphoma. Citation Format: Rachel Wirth, Sangeetha Rajagopalan, Erin Willert, William Null, Jennifer Erdman, Jen-Sing Liu, Jack P. Higgins. Engineered toxin body demonstrating CD20-specific binding and cell kill in B-cell non-Hodgkin's lymphoma cells. [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 5477. doi:10.1158/1538-7445.AM2013-5477

In Vitro and In Vivo Evaluation of a Humanized Anti-APRIL Antibody

A proliferation-inducing ligand (APRIL) is overexpressed in many cancers such as colorectal, gastric and liver. Silence APRIL gene or neutralize its expression may serve as therapeutic strategies to manage those cancers. Current phase I clinical trial shows that heavily pretreated patients were well tolerated high dose intravenous infusion. Herein, we report a humanized antibody (Ab) that neutralizes APRIL protein and inhibits cancer cell proliferation both in vitro and in vivo. The Ab was generated through conjugating foreign immunodominant T-helper cell (Th) epitopes to the N- or C-terminal of four soluble APRIL mutants. In vitro anti-proliferation effects were evaluated in both Raji and Jurkat cell lines. In vivo inhibition of tumor growth was determined in a tumor xenograft animal model with green fluorescent protein (GFP) positive Raji cell line. In vitro data demonstrated that this Ab significantly inhibited both Raji and Jurkat cell proliferation in a dose-dependent manner. The molecular imaging data demonstrated in vivo tumor growth delay when animals were treated with Ab. In conclusion, we have developed a humanized anti-APRIL Ab, which is effective in inhibiting tumor cell proliferations both in vitro and vivo. The humanized Ab has potential to reduce the immunoresponse in the clinical situation. This Ab also can be used in other APRIL mediated diseases such as Sjogren syndrome, multiple sclerosis and systemic lupus erythematosus.

Potential therapeutic strategy for non-Hodgkin lymphoma by anti-CD20scFvFc/CD28/CD3zeta gene tranfected T cells

BackgroundAnti-CD20 monoclonal antibody treatment has not only increased survival and cure rates in many non-Hodgkin lymphomas, but also has prompted an explosion in the development of novel antibodies and biologically active substances with specific cellular targets in the field of malignancies treatment. Since the robust immune responses are elicited by the gene-modified T cells, gene based T cell therapy may also provide a powerful tool for cancer immunotherapy.MethodsIn this study, we developed a vector construction encoding a chimeric T cell receptor that recognizes the CD20 antigen and delivers co-stimulatory signals to achieve T cell activation. One non-Hodgkin lymphoma cell line Raji cells co-cultured with peripheral blood-derived T cells were stably transfected with anti-CD20scFvFc/CD28/CD3zeta gene or anti-CD20scFvFc gene. T cells expressing anti-CD20scFvFc/CD28/CD3zeta or anti-CD20scFvFc gene co-cultured with CD20 positive Raji cells for different times. Cell lysis assay was carried by [3H]TdR release assay. The expressions of Fas, Bcl-2 and Caspase-3 of Raji cells were detected by flow cytometric. The secretion of IFN-gamma and IL-2 in co-culture medium was tested by ELISA assay. Activity of AP-1 was analyzed by EMSA.ResultsFollowing efficient transduction of peripheral blood-derived T cells with anti-CD20scFvFc/CD28/CD3zeta gene, an obvious cell lysis of Raji cells was observed in co-culture. T cells transduced anti-CD20scFvFc/CD28/CD3zeta gene had superior secretion of IFN-gamma and IL-2 compared to T cells transduced anti-CD20scFvFc gene. Also it led to a much stronger Fas-induced apoptosis signaling transduction in target cancer cells.ConclusionSo adoptively T cells transduced anti-CD20scFvFc/CD28/CD3zeta gene mediates enhanced anti-tumor activities against CD20 positive tumor cells, suggesting a potential of gene-based immunotherapy for non-Hodgkin lymphoma.

Nuclear Factor-Kappa B Inhibition Reduces Markedly Cell Proliferation in Epstein-Barr Virus-Infected Stomach Cancer, But Affects Variably in Epstein-Barr Virus-Negative Stomach Cancer

ABSTRACTNuclear factor-kappa B (NF-κB) inhibition by NF-κB p65-specific siRNA induced a near-cessation of cell proliferation in EBV-positive stomach cancer cell, and notably diminished cell proliferation in EBV- positive Raji lymphoma cell. In EBV-negative stomach cancer cells, NF-κB inhibition affected variably cell proliferation. Regardless of cell type, NF-κB inhibition suppressed antiapoptotic function of NF-κB, and tended to promote the nuclear accumulation of beta-catenin. This inverse relationship between NF-κB and beta-catenin was evident in 120 resected gastric carcinomas. Conclusively, NF-κB inhibition may be beneficial in the therapy of EBV-positive stomach cancer, but influence variously EBV-negative stomach cancer.

Construction of a DNA vaccine encoding Flk-1 extracellular domain and C3d fusion gene and investigation of its suppressing effect on tumor growth.

Although the critical role of complement component C3d as a molecular adjuvant in preventing virus infection is well established, its role in cancer prophylaxis and treatment is unclear. In this study, we constructed a recombinant plasmid encoding Flk-1 and C3d3 fusion proteins and investigated its transient expression in vitro in transfected eukaryotic cells and its antibody response in immunized mice. Subsequently, we investigated the vaccine's ability to elicit an immune response leading to suppression of angiogenesis and tumor growth in mice bearing bladder transitional cell carcinoma. Using Western blotting, immunocytochemistry, and flow cytometry, we detected the expression of Flk-1 and C3d3 fusion proteins in COS-7 cells transfected with these recombinant plasmids. Further binding experiment using CR2 (C3d receptor) positive Raji cells that were incubated with transfected COS-7 supernatant indicated that C3d was successfully fused to Flk-1. Although both vaccines elicited peak antibody levels at 5 weeks, Flk-1-specific antibody titer in pSG.SS.Flk-1(ECD).C3d3.YL-immunized mice was significantly higher when compared to pSG.SS.Flk-1(ECD).YL-immunized mice. The results of experiments with bladder tumor-bearing mice showed that the vaccine inhibited tumor growth significantly. These results suggest that C3d plays a critical role in tumor immunotherapy by promoting antibody response in Flk-1-based DNA vaccines. This approach may provide a new strategy for the rational design of anti-angiogenic therapies for the treatment of solid tumors and provide a basis for the further exploitation and application of the anti-angiogenesis DNA vaccines.

Dual functional molecular imaging probe targeting CD20 with PET and optical imaging

The present study aimed to develop a monoclonal antibody (mAb)-based double functional probe for PET and near-infrared fluorescence (NIRF) targeting CD20 and to cross validate the targeting efficacy of this dual functional probe. NuB2, anti CD20 mAb was conjugated with Alexa Fluor 750 and 64Cu through DOTA chelator. PET and NIRF imaging was carried out at 30 min and 24 h post-injection with 64Cu-DOTA-NuB2-Alexa Fluor 750 in CD20 positive Raji lymphoma-bearing mice. Fluorescence intensity and radio-activity were studied by ex vivo biodistribution study at 30 min, 24 and 48 h after injection. Raji tumor showed significantly higher uptake of DOTA-NuB2-Alexa Fluor 750 than that of DOTA-Alexa Fluor 750 (p<0.05). Significant correlation was obtained between the organ-to-muscle ratios measured by the radioactivity and fluorescence intensity (p<2.2e-16, r=0.94). Our findings demonstrate the effectiveness and feasibility of preparing an effective mAb-based dual functional imaging agent for PET and NIRF targeting the CD20 expression in lymphoma.

The design, construction and function of a new chimeric anti-CD20 antibody

A novel murine IgM-type anti-human CD20 monoclonal antibody (mAb) 1-28 was prepared in our Lab, which can induce apoptosis and inhibit proliferation of Daudi and Raji cells. However, the efficacy of 1-28mAb in human cancer therapy is likely to be limited by human anti-mouse antibody responses. A chimeric antibody, C1-28, containing 1-28mAb variable region genes fused to human constant region genes (gamma 1, kappa) was constructed. However, C1-28 lost the antigen-binding activity. Here, using sequence similarity and known 3D structure of antibody variable regions as template, the spatial conformations of 1-28 variable regions (i.e. V(H) and V(L)) were analyzed with computer-guided homology modeling methods. According to the surface electrostatic distribution and interaction free energy analysis, the relationship between structure and stability of 1-28 variable regions was studied theoretically and a new chimeric anti-CD20 antibody scFv-Ig named 5S was designed. Expression level of 5S in the culture supernatant was determined to be around 50mug/mL using sandwich ELISA method with chimeric antibody Rituxan as reference. 5S retained its murine counterpart's binding activity by fluorescence-activated cell-sorting analysis. Furthermore, it could kill CD20 positive Daudi and Raji cells by complement-dependent cytotoxicity. For binding affinity often decreased even lost when IgM antibody was constructed into chimeric IgG1 form, our success give a hint about how to construct a IgG1-type chimeric antibody from IgM-type murine antibody to preserve its binding activity.

Etodolac Inhibits EBER Expression and Induces Bcl-2-Regulated Apoptosis in Burkitt’s Lymphoma Cells.

Abstract Cyclooxygenase-2 (COX-2) is reported to be an important cellular target for therapy in malignancies. The growth inhibitory effects of COX-2 inhibitors on malignancies have been demonstrated to be through not only COX-2 dependent, but also independent mechanisms. In this study, we showed that etodolac, COX-2 inhibitor, induced apoptosis via COX-2 independent pathway, and investigated the molecular details of etodolac-induced apoptosis in Burkitt’s lymphoma cells. In Daudi and Raji Burkitt’s lymphoma cell lines, which expressed no COX-2 enzyme, etodolac more strongly induced apoptosis compared to meloxicam. Moreover, Etodolac did not induce apoptosis to normal B lymphocytes. For the pathway of etodolac-induced apoptosis, reduction of anti-apoptotic bcl-2 mRNA and Bcl-2 protein, activation of Caspase-9 and -3, down-regulation of caspase inhibitors, c-IAP-1 and Survivin were involved. Moreover, EBER-1 and -2 expression in EBV positive Daudi and Raji cells were reduced to result in down-regulation of Bcl-2 by treatment with etodolac. It has been reported that etodolac has stereoisomers, R- and S- etodolac. We found that racemate of etodolac more strongly induced apoptosis in Daudi and Raji cells compared to R- or S- etodolac. In conclusion, our findings indicated etodolac inhibited EBERs expression and induced apoptosis via a Bcl-2-regulated pathway. Moreover, racemate of etodolac more effectively induced apoptosis than R- and/or S- etodolac. Therefore, these activities of etodolac potentially extend to the treatment of patients with Burkitt’s lymphoma resistant to chemotherapy.