Antibody-mediated delivery of a viral MHC-I epitope into the cytosol of target tumor cells repurposes virus-specific CD8+ T cells for cancer immunotherapy.

BACKGROUND: Redirecting pre-existing virus-specific cytotoxic CD8+ T lymphocytes (CTLs) to tumors by simulating a viral infection of the tumor cells has great potential for cancer immunotherapy. However, this strategy is limited by lack of amenable method for viral antigen delivery into the cytosol of target tumors. Here, we addressed the limit by developing a CD8+ T cell epitope-delivering antibody, termed a TEDbody, which was engineered to deliver a viral MHC-I epitope peptide into the cytosol of target tumor cells by fusion with a tumor-specific cytosol-penetrating antibody. METHODS: To direct human cytomegalovirus (CMV)-specific CTLs against tumors, we designed a series of TEDbodies carrying various CMV pp65 antigen-derived peptides. CMV-specific CTLs from blood of CMV-seropositive healthy donors were expanded for use in in vitro and in vivo experiments. Comprehensive cellular assays were performed to determine the presentation mechanism of TEDbody-mediated CMV peptide-MHC-I complex (CMV-pMHCI) on the surface of target tumor cells and the recognition and lysis by CMV-specific CTLs. In vivo CMV-pMHCI presentation and antitumor efficacy of TEDbody were evaluated in immunodeficient mice bearing human tumors. RESULTS: TEDbody delivered the fused epitope peptides into target tumor cells to be intracellularly processed and surface displayed in the form of CMV-pMHCI, leading to disguise target tumor cells as virally infected cells for recognition and lysis by CMV-specific CTLs. When systemically injected into tumor-bearing immunodeficient mice, TEDbody efficiently marked tumor cells with CMV-pMHCI to augment the proliferation and cytotoxic property of tumor-infiltrated CMV-specific CTLs, resulting in significant inhibition of the in vivo tumor growth by redirecting adoptively transferred CMV-specific CTLs. Further, combination of TEDbody with anti-OX40 agonistic antibody substantially enhanced the in vivo antitumor activity. CONCLUSION: Our study offers an effective technology for MHC-I antigen cytosolic delivery. TEDbody may thus have utility as a therapeutic cancer vaccine to redirect pre-existing anti-viral CTLs arising from previously exposed viral infections to attack tumors.

VSIG4-expressing tumor-associated macrophages impair anti-tumor immunity.

VSIG4, a newly identified co-inhibitory molecule belonging to the B7-related family, is exclusively expressed on tissue-resident macrophages and is involved in the suppression of T cell proliferation and cytokine production. We sought to characterize the role of VSIG4 in anti-tumor immunity in the tumor microenvironment, focusing on VSIG4-expressing tumor-associated macrophages (TAMs). We found that VSIG4-expressing TAMs negatively regulated antigen-specific T cell proliferation and cytokine production through direct inhibition via cell cycle arrest, but not apoptosis, as well as through their arginase 1 activity. Furthermore, VSIG4-expressing TAMs suppress tumor-specific CD8+ T cell cytotoxicity. Therefore, our results suggest that VSIG4-expressing TAMs could be a negative cellular regulator of anti-tumor immunity in the tumor microenvironment.

Affinity Maturation of a T-Cell Receptor-Like Antibody Specific for a Cytomegalovirus pp65-Derived Peptide Presented by HLA-A*02:01.

Human cytomegalovirus (CMV) infection is widespread among adults (60-90%) and is usually undetected in healthy individuals without symptoms but can cause severe diseases in immunocompromised hosts. T-cell receptor (TCR)-like antibodies (Abs), which recognize complex antigens (peptide-MHC complex, pMHC) composed of MHC molecules with embedded short peptides derived from intracellular proteins, including pathogenic viral proteins, can serve as diagnostic and/or therapeutic agents. In this study, we aimed to engineer a TCR-like Ab specific for pMHC comprising a CMV pp65 protein-derived peptide (495NLVPMVATV503; hereafter, CMVpp65495-503) in complex with MHC-I molecule human leukocyte antigen (HLA)-A*02:01 (CMVpp65495-503/HLA-A*02:01) to increase affinity by sequential mutagenesis of complementarity-determining regions using yeast surface display technology. Compared with the parental Ab, the final generated Ab (C1-17) showed ~67-fold enhanced binding affinity (KD ≈ 5.2 nM) for the soluble pMHC, thereby detecting the cell surface-displayed CMVpp65495-503/HLA-A*02:01 complex with high sensitivity and exquisite specificity. Thus, the new high-affinity TCR-like Ab may be used for the detection and treatment of CMV infection.

West Nile virus T-cell ligand sequences shared with other flaviviruses: a multitude of variant sequences as potential altered peptide ligands.

Phylogenetic relatedness and cocirculation of several major human pathogen flaviviruses are recognized as a possible cause of deleterious immune responses to mixed infection or immunization and call for a greater understanding of the inter-Flavivirus protein homologies. This study focused on the identification of human leukocyte antigen (HLA)-restricted West Nile virus (WNV) T-cell ligands and characterization of their distribution in reported sequence data of WNV and other flaviviruses. H-2-deficient mice transgenic for either A2, A24, B7, DR2, DR3, or DR4 HLA alleles were immunized with overlapping peptides of the WNV proteome, and peptide-specific T-cell activation was measured by gamma interferon (IFN-γ) enzyme-linked immunosorbent spot (ELISpot) assays. Approximately 30% (137) of the WNV proteome peptides were identified as HLA-restricted T-cell ligands. The majority of these ligands were conserved in ∼≥88% of analyzed WNV sequences. Notably, only 51 were WNV specific, and the remaining 86, chiefly of E, NS3, and NS5, shared an identity of nine or more consecutive amino acids with sequences of 64 other flaviviruses, including several major human pathogens. Many of the shared ligands had an incidence of >50% in the analyzed sequences of one or more of six major flaviviruses. The multitude of WNV sequences shared with other flaviviruses as interspecies variants highlights the possible hazard of defective T-cell activation by altered peptide ligands in the event of dual exposure to WNV and other flaviviruses, by either infection or immunization. The data suggest the possible preferred use of sequences that are pathogen specific with minimum interspecies sequence homology for the design of Flavivirus vaccines.

Protective role of V-set and immunoglobulin domain-containing 4 expressed on kupffer cells during immune-mediated liver injury by inducing tolerance of liver T- and natural killer T-cells.

UNLABELLED: V-set and Ig domain-containing 4 (VSIG4, CRIg, or Z39Ig), a newly identified B7-related cosignaling molecule, is a complement receptor and a coinhibitory ligand that negatively regulates T-cell immunity. Despite its exclusive expression on liver Kupffer cells (KCs) that play key roles in liver tolerance, the physiological role of VSIG4 in liver tolerance remains undefined. Mice lacking VSIG4 had poor survival rates and severe liver pathology in a concanavalin A (ConA)-induced hepatitis (CIH) model, which could be prevented by adoptive transfer of VSIG4(+) KCs. The absence of VSIG4 rendered endogenous liver T- and natural killer T (NKT)-cells more responsive to antigen-specific stimulation and impaired tolerance induction in those cells against their cognate antigens. T-cell costimulation with VSIG4.Ig suppressed Th1-, Th2-, and Th17-type cytokine production and arrested the cell cycle at the G(0) /G(1) phase but did not induce apoptosis in vitro. VSIG4-mediated tolerance induction and cell-cycle arrest were further supported by down-regulation of G(1) phase-specific Cdk2, Cdk4, and Cdk6, and up-regulation of tolerance-inducing p27(KIP-1) in VSIG4.Ig-stimulated T-cells. Administration of soluble VSIG4.Ig to wildtype mice prevented CIH development and prolonged the survival of mice with established CIH. CONCLUSION: Collectively, our results suggest that VSIG4(+) KCs play a critical role in the induction and maintenance of liver T- and NKT-cell tolerance, and that modulation of the VSIG4 pathway using a VSIG4.Ig fusion protein may provide useful immunological therapies against immune-mediated liver injury including autoimmune hepatitis.

Improved intratumoral penetration of IL12 immunocytokine enhances the antitumor efficacy.

Tumor-targeting antibody (Ab)-fused cytokines, referred to as immunocytokines, are designed to increase antitumor efficacy and reduce toxicity through the tumor-directed delivery of cytokines. However, the poor localization and intratumoral penetration of immunocytokines, especially in solid tumors, pose a challenge to effectively stimulate antitumor immune cells to kill tumor cells within the tumor microenvironment. Here, we investigated the influence of the tumor antigen-binding kinetics of a murine interleukin 12 (mIL12)-based immunocytokine on tumor localization and diffusive intratumoral penetration, and hence the consequent antitumor activity, by activating effector T cells in immunocompetent mice bearing syngeneic colon tumors. Based on tumor-associated antigen HER2-specific Ab Herceptin (HCT)-fused mIL12 carrying one molecule of mIL12 (HCT-mono-mIL12 immunocytokine), we generated a panel of HCT-mono-mIL12 variants with different affinities (K D) mainly varying in their dissociation rates (k off) for HER2. Systemic administration of HCT-mono-mIL12 required an anti-HER2 affinity above a threshold (K D = 130 nM) for selective localization and antitumor activity to HER2-expressing tumors versus HER2-negative tumors. However, the high affinity (K D = 0.54 or 46 nM) due to the slow k off from HER2 antigen limited the depth of intratumoral penetration of HCT-mono-mIL12 and the consequent tumor infiltration of T cells, resulting in inferior antitumor activity compared with that of HCT-mono-mIL12 with moderate affinity of (K D = 130 nM) and a faster k off. The extent of intratumoral penetration of HCT-mono-mIL12 variants was strongly correlated with their tumor infiltration and intratumoral activation of CD4+ and CD8+ T cells to kill tumor cells. Collectively, our results demonstrate that when developing antitumor immunocytokines, tumor antigen-binding kinetics and affinity of the Ab moiety should be optimized to achieve maximal antitumor efficacy.

Engineering of Humanized Antibodies Against Human Interleukin 5 Receptor Alpha Subunit That Cause Potent Antibody-Dependent Cell-Mediated Cytotoxicity.

Patients with severe eosinophilic asthma (SEA; characterized by persistent eosinophilia in blood and airway tissues) experience frequent asthma exacerbations with poor clinical outcomes. Interleukin 5 (IL-5) and IL-5 receptor alpha subunit (IL-5α) play key roles in eosinophilia maintenance, and relevant therapeutic strategies include the development of antibodies (Abs) against IL-5 or IL-5α to control eosinophilia. Benralizumab, an anti-IL-5α Ab that depletes eosinophils mainly via Ab-dependent cell-mediated cytotoxicity and through blockage of IL-5 function on eosinophils, has been clinically approved for patients with SEA. Here, we report engineering of a new humanized anti-IL-5Rα Ab with potent biological activity. We first raised murine Abs against human IL-5Rα, humanized a leading murine Ab, and then further engineered the humanized Abs to enhance their affinity for IL-5Rα using the yeast surface display technology. The finally engineered version of the Ab, 5R65.7, with affinity (KD ≈ 4.64 nM) stronger than that of a clinically relevant benralizumab analogue (KD ≈ 26.8 nM) showed improved neutralizing activity toward IL-5-dependent cell proliferation in a reporter cell system. Domain level Ab epitope mapping revealed that 5R65.7 recognizes membrane-proximal domain 3 of IL-5Rα, distinct from domain I epitope of the benralizumab analogue. In ex vivo assays with peripheral eosinophils from patients with SEA and healthy donors, 5R65.7 manifested more potent biological activities than the benralizumab analogue did, including inhibition of IL-5-dependent proliferation of eosinophils and induction of eosinophil apoptosis through autologous natural-killer-cell-mediated Ab-dependent cell-mediated cytotoxicity. Our study provides a potent anti-IL-5Rα Ab, 5R65.7, which is worthy of further testing in preclinical and clinical trials against SEA as a potential alternative to the current therapeutic arsenal.

A Neuropilin-1 Antagonist Exerts Antitumor Immunity by Inhibiting the Suppressive Function of Intratumoral Regulatory T Cells.

Regulatory T cells (Treg) are targeted for cancer immunotherapy because they suppress antitumor immunity. Although the importance of neuropilin-1 (NRP1) in the stability and function of intratumoral Tregs is well-documented, targeting of NRP1+ Tregs for anticancer immunotherapy has not been well explored. Here, we found that an NRP1 antagonist [Fc(AAG)-TPP11], generated by fusion of the NRP1-specific binding peptide TPP11 with the C-terminus of an effector function-deficient immunoglobulin Fc(AAG) variant, inhibits intratumoral NRP1+ Treg function and stability. Fc(AAG)-TPP11 triggered the internalization of NRP1, reducing its surface expression on Tregs and thereby inhibiting the suppressive function of Tregs. In two murine syngeneic tumor models, Fc(AAG)-TPP11 retarded tumor growth, comparable with a Treg-depleting anti-CTLA-4 antibody, without noticeable toxicity. Fc(AAG)-TPP11 inhibited NRP1-dependent Treg function, inducing unstable intratumoral Tregs, with reduced expression of Foxp3 and enhanced production of IFNγ, which subsequently increased the functionality and frequency of intratumoral CD8+ T cells. We also observed selective expression of NRP1 on Tregs isolated from human tumors, but not from the blood of healthy donors and patients with cancer, as well as ex vivo inhibition of intratumoral NRP1+ Treg function by Fc(AAG)-TPP11. Our results suggest that the NRP1 antagonist Fc(AAG)-TPP11 has therapeutic potential for the inhibition of intratumoral NRP1+ Tregs with limited unfavorable effects on peripheral Tregs.

Engineering of anti-human interleukin-4 receptor alpha antibodies with potent antagonistic activity.

Development of antagonistic antibody (Ab) against interleukin-4 receptor alpha (IL-4Rα) subunit of IL-4/IL-13 receptors is a promising therapeutic strategy for T helper 2 (TH2)-mediated allergic diseases such as asthma and atopic dermatitis. Here we isolated anti-human IL-4Rα antagonistic Abs from a large yeast surface-displayed human Ab library and further engineered their complementarity-determining regions to improve the affinity using yeast display technology, finally generating a candidate Ab, 4R34.1.19. When reformatted as human IgG1 form, 4R34.1.19 specifically bound to IL-4Rα with a high affinity (KD ≈ 178 pM) and effectively blocked IL-4- and IL-13-dependent signaling in a reporter cell system at a comparable level to that of the clinically approved anti-IL-4Rα dupilumab Ab analogue. Epitope mapping by alanine scanning mutagenesis revealed that 4R34.1.19 mainly bound to IL-4 binding sites on IL-4Rα with different epitopes from those of dupilumab analogue. Further, 4R34.1.19 efficiently inhibited IL-4-dependent proliferation of T cells among human peripheral blood mononuclear cells and suppressed the differentiation of naïve CD4+ T cells from healthy donors and asthmatic patients into TH2 cells, the activities of which were comparable to those of dupilumab analogue. Our work demonstrates that both affinity and epitope are critical factors for the efficacy of anti-IL-4Rα antagonistic Abs.

Heterodimeric Fc-fused IL12 shows potent antitumor activity by generating memory CD8+ T cells.

Interleukin-12 (IL12) (p35/p40 complex) is a heterodimeric cytokine with potent anti-tumor activity. However, its short serum half-life and high dose-related toxicities limit its clinical efficacy. Here, we constructed heterodimeric immunoglobulin Fc-fused mouse IL12 (mIL12) in a monovalent binding format (mono-mIL12-Fc) to generate long-acting mIL12 in the naturally occurring heterodimeric form. Mono-mIL12-Fc exhibited a much longer plasma half-life than recombinant mIL12, enabling twice-weekly systemic injections to remove established tumors in syngeneic mouse models. Mono-mIL12-Fc was more potent than wild-type Fc-based bivalent-binding IL12-Fc (bi-mIL12-Fc) for eradicating large established immunogenic tumors without noticeable toxicities by enhancing interferon-γ production and the proliferation of immune effector cells in tumors. More importantly, mono-mIL12-Fc triggered weaker IL12 signaling than bi-mIL12-Fc, favoring the generation of functional and protective memory CD8+ T cells. Our results demonstrate that heterodimeric-Fc-fused IL12 is a suitable format for augmenting adaptive CD8+ T cell immune responses, providing a practical alternative to the systemic administration of IL12 for antitumor therapy.

Antibody targeting intracellular oncogenic Ras mutants exerts anti-tumour effects after systemic administration.

Oncogenic Ras mutants, frequently detected in human cancers, are high-priority anticancer drug targets. However, direct inhibition of oncogenic Ras mutants with small molecules has been extremely challenging. Here we report the development of a human IgG1 format antibody, RT11, which internalizes into the cytosol of living cells and selectively binds to the activated GTP-bound form of various oncogenic Ras mutants to block the interactions with effector proteins, thereby suppressing downstream signalling and exerting anti-proliferative effects in a variety of tumour cells harbouring oncogenic Ras mutants. When systemically administered, an RT11 variant with an additional tumour-associated integrin binding moiety for tumour tissue targeting significantly inhibits the in vivo growth of oncogenic Ras-mutated tumour xenografts in mice, but not wild-type Ras-harbouring tumours. Our results demonstrate the feasibility of developing therapeutic antibodies for direct targeting of cytosolic proteins that are inaccessible using current antibody technology.

Longer aging time increases the anticancer and antimetastatic properties of doenjang.

OBJECTIVE: Fermented soy foods, such as doenjang, are important components of the Korean diet. Doenjang has been shown to have greater antimutagenic and anticancer activities than other fermented soybean foods such as chungkukjang (Korean-style natto) and miso and non-fermented soybeans. This study investigated the effects of fermentation time of doenjang on its inhibitory activity against solid tumor formation and lung metastasis. METHODS: Effects of methanol extracts from doenjang prepared with long-term fermentation on tumor formation, natural killer cell activity in spleen, and glutathione S-transferase activity in liver were investigated in sarcoma-180 cell-transplanted mice. Inhibitory effects of these samples on lung metastasis of colon 26-M3.1 cells were also evaluated in Balb/c mice. To determine the effect of aging on functionality, doenjang fermented for 3, 6, and 24 mo were evaluated. RESULTS: Doenjang fermented for 24 mo exhibited a two- to three-fold increase in antitumor effects on sarcoma-180-injected mice and antimetastatic effects in colon 26-M 3.1 cells in mice compared with the 3- or 6-mo fermented doenjang. The 24-mo fermentation was the most effective in preventing cancer by decreasing tumor formation and increasing natural killer cell activity in spleens and glutathione S-transferase activity in livers of mice. CONCLUSIONS: Prolonging the fermentation period when making doenjang increases its antitumor and antimetastatic effects in vivo.

Endogenous VSIG4 negatively regulates the helper T cell-mediated antibody response.

VSIG4 acts as a co-inhibitory ligand to negatively regulate T cell proliferation and cytokine production, and its expression is restricted to macrophages. We hypothesized that endogenous VSIG4 impairs helper T cell functions and then inhibits the subsequent antibody response. Isotype switching of ovalbumin (OVA)-specific antibody subclasses to IgG1, IgG2a, IgG2b, and IgG3 was enhanced in OVA-immunized VSIG4 knockout (KO) mice. 2,4,6-Trinitrophenyl hapten (TNP) - Keyhole Limpet Hemocyanin (KLH)-primed B cells cocultured with OVA-primed CD4(+) T cells from OVA-immunized VSIG4 KO mice in the presence of TNP-OVA showed enhanced isotype switching to IgG subclasses compared to those cocultured with cells isolated from OVA-immunized wild-type (WT) mice. Furthermore, the levels of CD40L expression, the frequency of memory CD4(+) T cells, and the production of isotype switching-inducing cytokines increased significantly in OVA-primed CD4(+) T cells from VSIG4 KO mice. T cells from OVA-specific T cell receptor (TCR) transgenic mice produced more IFN-γ when cocultured with macrophages from VSIG4 KO mice compared to WT mice. Thus, our results demonstrate that macrophage-associated VSIG4 plays a negative role in helper T cell-dependent isotype switching by inhibiting helper T cell activation and differentiation, and suppressing the isotype switching-inducing cytokine production in antigen-primed CD4(+) helper T cells.

Induction of Bax and activation of caspases during beta-sitosterol-mediated apoptosis in human colon cancer cells.

beta-sitosterol, a main dietary phytosterol found in plants, may have the potential for prevention and therapy for human cancer. The purpose of the present study was to examine the effect of beta-sitosterol on the growth of HT116 human colon cancer cells. Treatment with beta-sitosterol resulted in a dose-dependent growth inhibition coupled with the characteristic morphological features of apoptosis and with the increase of a sub-G1 cell population. Apoptosis-inducing concentrations of beta-sitosterol induced caspase-3 and caspase-9 activation accompanied by proteolytic cleavage of poly(ADP-ribose)-polymerase. In addition, beta-sitosterol-induced apoptosis in HT116 cells was associated with a decreased expression of the anti-apototic Bcl-2 protein and mRNA and a concomitant increase of the pro-apototic Bax protein and mRNA, and with release of cytochrome c from the mitochondria into the cytosol. beta-sitosterol treatment also inhibited the expression of cIAP-1 without significant changes in the level of cIAP-2. Taken together, these findings provide important new insights into the possible molecular mechanisms of the anti-cancer activity of beta-sitosterol.

Antimutagenic effects of doenjang (Korean fermented soypaste) and its active compounds.

Doenjang (Korean fermented soypaste) is one of the important fermented foods of Korea. Doenjang has been traditionally manufactured from meju, which is fermented rectangular shape molded from crushed cooked soybeans. The main microorganisms involved for meju fermentation are Bacillus subtilis and molds such as Rizopus sp., Mucor sp., and Aspergillus sp. We have already reported that doenjang is safe from mycotoxin, especially, aflatoxin contamination due to the manufacturing process of the doenjang. We have demonstrated that the doenjang extracts showed strong antimutagenic activities against various carcinogens/mutagens including aflatoxin B(1). The traditionally fermented soypaste, doenjang showed higher antimutagenic activity than the raw soybeans, cooked soybeans, meju and other fermented soybeans in the Ames test. The active compounds that were identified are genistein, linoleic acid, beta-sitosterol glucoside, soyasaponin, etc. The active compounds exhibited strong antimutagenic activities in the Ames test, SOS chromotest and Drosophila wing spot test. More genistein was formed during the doenjang fermentation from genistin in the soybeans. Genistein and linoleic acid were the most effective active compounds found in doenjang.

Curcumin inhibits the growth of AGS human gastric carcinoma cells in vitro and shows synergism with 5-fluorouracil.

The inhibitory effect of curcumin and its synergism with 5-fluorouracil (5-FU) on the growth of the AGS human gastric carcinoma cell line was examined. Cell cycle analysis was used to elucidate the mechanisms for the inhibition by curcumin. Curcumin significantly inhibited the growth of AGS cells in a dose- and time-dependent manner (P <.05). Curcumin caused a 34% decrease in AGS proliferation at 5 micromol/L, 51% at 10 micromol/L, and 92% at 25 micromol/L after 4 days of treatment. When curcumin (10 micromol/L) was removed after a 24-hour exposure, the growth pattern of curcumin-treated AGS cells was similar to that of control cells, suggesting reversibility of curcumin on the growth of AGS cells. Combining curcumin with 5-FU significantly increased growth inhibition of AGS cells compared with either curcumin or 5-FU alone (P <.05), suggesting synergistic actions of the two drugs. After 4 days of treatment with 10 micromol/L of curcumin, the G2/M phase fraction of cells was 60.5% compared with 22.0% of the control group, suggesting a G2/M block by curcumin treatment. Because the curcumin concentrations (5 micromol/L) used in our study were similar to steady-state concentrations (1.77 +/- 1.87 micromol/L) in human serum of subjects receiving chronic administration of a commonly recommended dose (8 g/day), curcumin may be useful for the treatment of gastric carcinoma, especially in conjunction with 5-FU.

Kimchi and an active component, beta-sitosterol, reduce oncogenic H-Ras(v12)-induced DNA synthesis.

The Korean fermented vegetable food, kimchi, has been demonstrated to have anticancer functional properties. This study examined the effect of kimchi samples, methanol extracts of commercially grown baechu cabbage kimchi (CK) and organically grown baechu cabbage kimchi (OK), as well as the dichloromethane fraction (DCM fr.) from CK, and the active compound (AC), which has been identified as largely beta-sitosterol, from DCM fr., on the Ras-dependent signaling pathway. CK, OK, and DCM fr. exhibited a greater inhibition against the proliferation of Rat2 fibroblasts transformed with Ras(v12) (HO6) than parental Rat2 fibroblasts. In addition, OK and DCM fr. showed a higher inhibitory effect than CK. Furthermore, we employed the single-cell microinjection technique, combined with 3-bromo-5'-deoxyuridine incorporation, to examine the effects of kimchi samples on DNA synthesis induced by microinjected oncogenic Ras(v12). When the DCM fr. and AC were used to treat Rat1 fibroblasts overexpressing human insulin receptors (HIRc-B) and microinjected with oncogenic H-Ras(v12), the DNA synthesis of injected cells was decreased, suggesting that kimchi might block the signaling pathway of oncogenic Ras(v12), thus preventing the proliferation of transformed cells. This study provides additional evidence that kimchi and its active components, including beta-sitosterol, have potential in both the prevention and treatment of cancer, and presents convincing evidence that the anticancer effects may be a result of an inhibition of Ras oncogene signaling.

Emerging Co-signaling Networks in T Cell Immune Regulation.

Co-signaling molecules are surface glycoproteins that positively or negatively regulate the T cell response to antigen. Co-signaling ligands and receptors crosstalk between the surfaces of antigen-presenting cells (APCs) and T cells, and modulate the ultimate magnitude and quality of T cell receptor (TCR) signaling. In the past 10 years, the field of co-signaling research has been advanced by the understanding of underlying mechanisms of the immune modulation led by newly identified co-signaling molecules and the successful preclinical and clinical trials targeting co-inhibitory molecules called immune checkpoints in the treatment of autoimmune diseases and cancers. In this review, we briefly describe the characteristics of well-known B7 co-signaling family members regarding the expression, functions and therapeutic implications and to introduce newly identified B7 members such as B7-H5, B7-H6, and B7-H7.

Tumor cells loaded with α-galactosylceramide promote therapeutic NKT-dependent anti-tumor immunity in multiple myeloma.

Tumor cells have been used as the tumor antigen sources for developing cancer vaccines. Due to their low immunogenicity, tumor antigens are combined with various adjuvants to enhance immunogenicity of cancer vaccines. Among them, a natural killer T cell (NKT)-ligand, α-galactosylceramide (αGC) has been reported as a powerful adjuvant showing therapeutic effects in solid tumors as well as hematological malignancies including lymphoma. In this study, we applied αGC-based tumor cell vaccine in mouse multiple myeloma model. The αGC-loaded MOPC315BM myeloma cell vaccine efficiently retarded tumor growth, induced regression of established tumors, and protected surviving mice from tumor rechallenge. Therapeutic responses were associated with induction of strong humoral immune responses, including myeloma-specific antibodies, and cellular immune responses, including myeloma-specific CD8(+) cytotoxic T lymphocytes and memory T cells. In addition, regulatory T cells were significantly decreased in mice that received the αGC-loaded myeloma cell vaccine. Thus, our results demonstrated that αGC-loaded myeloma vaccine efficiently promoted NKT-dependent anti-tumor immunity in a mouse model. These findings are informative for improving the efficacy of tumor-cell-based immunotherapy for patients with MM and other CD1d-expressing tumors.