Rapid activation of IL-2 receptor signaling by CD301b+ DC-derived IL-2 dictates the outcome of helper T cell differentiation.

Effector T helper (Th) cell differentiation is fundamental to functional adaptive immunity. Different subsets of dendritic cells (DCs) preferentially induce different types of Th cells, but the fate instruction mechanism for Th type 2 (Th2) differentiation remains enigmatic, as the critical DC-derived cue has not been clearly identified. Here, we show that CD301b+ DCs, a major Th2-inducing DC subset, drive Th2 differentiation through cognate interaction by 'kick-starting' IL-2 receptor signaling in CD4T cells. Mechanistically, CD40 engagement induces IL-2 production selectively from CD301b+ DCs to maximize CD25 expression in CD4 T cells, which is required specifically for the Th2 fate decision. On the other hand, CD25 in CD301b+ DCs facilitates directed action of IL-2 toward cognate CD4T cells. Furthermore, CD301b+ DC-derived IL-2 skews CD4T cells away from the T follicular helper fate. These results highlight the critical role of DC-intrinsic CD40-IL-2 axis in bifurcation of Th cell fate.

Role of mouse dendritic cell subsets in priming naive CD4 T cells.

Conventional dendritic cells (cDCs) are potent antigen-presenting cells that consist of developmentally, phenotypically, and functionally distinct subsets. Following immunization, each subset of cDCs acquires the antigen and presents it to CD4T (CD4+ T (cells)) cells with distinct spatiotemporal kinetics in the secondary lymphoid organs, often causing multiple waves of antigen presentation to CD4T cells. Here, we review the current understanding of the kinetics of antigen presentation by each cDC subset and its functional consequences in priming naive CD4T cells, and discuss its implications in the differentiation of CD4T cells.

Protocol to quantify and characterize contact between T cells and antigen-presenting cells in the antigen-draining lymph nodes of mice using flow cytometry.

Physical contact between T cells and antigen-presenting cells (APCs) is essential for priming antigen-specific T cells, but quantitating the antigen-dependent T cell-APC contact can be laborious. Here, we present a simple flow-cytometry-based protocol for quantitating T cell-APC contacts in the antigen-draining lymph node in mice immunized with ovalbumin (OVA). This protocol quantifies the contact between adoptively transferred OVA-specific TCR transgenic CD4T (OT-II) cells and dendritic cell (DC) subsets. This approach can be applied to other types of intercellular interactions between T cells and APCs. For complete details on the use and execution of this protocol, please refer to Tatsumi et al. (2021).1.

Effective CD4 T cell priming requires repertoire scanning by CD301b+ migratory cDC2 cells upon lymph node entry.

During the initiation of adaptive immune responses, millions of lymphocytes must be scanned to find the few cognate clones. The activation mechanisms of CD4 T cells have been extensively studied, but the cellular mechanisms that drive selection of cognate clones are not completely understood. Here, we show that recently homed naïve polyclonal CD4 T cells are temporarily retained before leaving the lymph node. This stop-and-go traffic of CD4 T cells provides an adequate time window for efficient scanning and timely priming of antigen-specific cognate clones. CD301b+ DCs, a major subset of migratory cDC2 cells, localize to the areas around high endothelial venules, where they retain incoming polyclonal CD4 T cells through MHCII-dependent but antigen-independent mechanisms, while concurrently providing cognate stimuli for priming. These results indicate that CD301b+ DCs function as an immunological "display window" for CD4 T cells to efficiently scan their antigen specificity.

An Essential Role of the Avidity of T-Cell Receptor in Differentiation of Self-Antigen-reactive CD8+ T Cells.

Many studies demonstrated crucial roles of avidity of T-cell receptor (TCR) in T-cell fate. However, majority of these findings resulted from analysis of non-self-antigen-specific CD8 T cells, and little is known about roles of TCR avidity in the fate of self-antigen-specific CD8 T cells. Wilms tumor gene 1 (WT1) protein is a self-antigen most suitable for addressing this issue because WT1 protein is a highly immunogenic, typical self-antigen. Here, we isolated 2 distinct and functional TCRs, TCR1 and TCR2, from murine WT1 peptide (RMFPNAPYL)-specific cytotoxic T lymphocytes (WT1-CTLs) and generated TCR1-retrogenic (Rg) and TCR2-Rg mice under T and B-cell-deficient and -reconstituted conditions. TCR1-transduced CD8 T (TCR1-T) cells had approximately 2-fold higher avidity to WT1 peptide than TCR2-transduced CD8 T (TCR2-T) cells. Cytokine production profiles and cell surface phenotypes showed that TCR1-T cells were more differentiated than TCR2-T cells under both conditions. Therefore, TCR1-T cells with TCR avidity higher than that of TCR2-T cells are more differentiated compared with TCR2-T cells. Furthermore, TCR1-T cells that developed under T and B-cell-reconstituted conditions displayed cytotoxicity against endogenously WT1-expressing tumor cells, whereas TCR2 T cells that developed under the same conditions did not. Thus, it was demonstrated, for the first time, that TCR avidity played an essential role in differentiation of self-antigen-reactive T cells, through the success of establishment of two distinct WT1-CTLs with a difference in only TCR avidity under the identical genetic background. Present results should provide us with an insight for elucidation of the differentiation mechanisms of self-antigen-reactive T cells, including tumor antigen-reactive T cells.

Glycosylation Status of CD43 Protein Is Associated with Resistance of Leukemia Cells to CTL-Mediated Cytolysis.

To improve cancer immunotherapy, it is important to understand how tumor cells counteract immune-surveillance. In this study, we sought to identify cell-surface molecules associated with resistance of leukemia cells to cytotoxic T cell (CTL)-mediated cytolysis. To this end, we first established thousands of monoclonal antibodies (mAbs) that react with MLL/AF9 mouse leukemia cells. Only two of these mAbs, designated R54 and B2, bound preferentially to leukemia cells resistant to cytolysis by a tumor cell antigen-specific CTLs. The antigens recognized by these mAbs were identified by expression cloning as the same protein, CD43, although their binding patterns to subsets of hematopoietic cells differed significantly from each other and from a pre-existing pan-CD43 mAb, S11. The epitopes of R54 and B2, but not S11, were sialidase-sensitive and expressed at various levels on leukemia cells, suggesting that binding of R54 or B2 is associated with the glycosylation status of CD43. R54high leukemia cells, which are likely to express sialic acid-rich CD43, were highly resistant to CTL-mediated cytolysis. In addition, loss of CD43 in leukemia cells or neuraminidase treatment of leukemia cells sensitized leukemia cells to CTL-mediated cell lysis. These results suggest that sialic acid-rich CD43, which harbors multiple sialic acid residues that impart a net negative surface charge, protects leukemia cells from CTL-mediated cell lysis. Furthermore, R54high or B2high leukemia cells preferentially survived in vivo in the presence of adaptive immunity. Taken together, these results suggest that the glycosylation status of CD43 on leukemia is associated with sensitivity to CTL-mediated cytolysis in vitro and in vivo. Thus, regulation of CD43 glycosylation is a potential strategy for enhancing CTL-mediated immunotherapy.

Induction of eEF2-specific antitumor CTL responses in vivo by vaccination with eEF2-derived 9mer-peptides.

Eukaryotic elongation factor 2 (eEF2) is an essential factor for protein synthesis. Previous studies have shown that the eEF2 gene was overexpressed and plays an oncogenic role in various types of cancers and that eEF2 gene product elicited both humoral immune responses to produce eEF2-specific IgG autoantibody in cancer-bearing individuals and cellular immune responses to induce eEF2 peptide-specific cytotoxic T lymphocytes (CTLs) in vitro. The purpose of the present study was to induce eEF2-specific, antitumor CTL responses in vivo by vaccination with MHC class I-binding eEF2-derived peptide. First, two mouse MHC class I-restricted eEF2­derived, 9-mer peptides, EF17 (17-25 aa, ANIRNMSVI) and EF180 (180-188 aa, RIVENVNVI) were identified as eEF2-specific CTL peptides, and mice were vaccinated intradermally eight times with either EF17 or EF180 peptide emulsified with Montanide ISA51 adjuvant. Cytotoxicity assay showed that eEF2-specific CTLs were induced in both EF17­and EF180­vaccinated mice, and histological study showed no detectable damage in the organs of these mice. Next, to examine in vivo antitumor effects of eEF2 peptide vaccination in a therapeutic model, mice were vaccinated four times with one each of the two eEF2 peptides at weekly intervals after implantation of eEF2-expressing leukemia cells. The vaccination with eEF2 peptides induced eEF2-specific CTLs and suppressed tumor growth, and disease-free survival was significantly longer in EF180-vaccinated mice compared to control mice. The survival was associated with the robustness of eEF2-specific CTL induction. These results indicate that vaccination with MHC class I-binding eEF2 peptide induced eEF2-targeting, antitumor CTL responses in vivo without damage to normal organs, which provided us a rationale for eEF2 peptide-based cancer immunotherapy.

Syndecan-4 as a biomarker to predict clinical outcome for glioblastoma multiforme treated with WT1 peptide vaccine.

AIM: In cancer immunotherapy, biomarkers are important for identification of responsive patients. This study was aimed to find biomarkers that predict clinical outcome of WT1 peptide vaccination. MATERIALS & METHODS: Candidate genes that were expressed differentially between long- and short-term survivors were identified by cDNA microarray analysis of peripheral blood mononuclear cells that were extracted from 30 glioblastoma patients (discovery set) prior to vaccination and validated by quantitative RT-PCR using discovery set and different 23 patients (validation set). RESULTS: SDC-4 mRNA expression levels distinguished between the long- and short-term survivors: 1-year survival rates were 64.0 and 18.5% in SDC4-low and -high patients, respectively. CONCLUSION: SDC-4 is a novel predictive biomarker for the efficacy of WT1 peptide vaccine.

A Zbtb7a proto-oncogene as a novel target for miR-125a.

In our previous study, we showed that miR-125a directly targeted a WT1 oncogene, which was overexpressed in leukemia and various kinds of solid tumors including lung, breast, gastric, and colon cancers, and brain tumors and was deeply involved in leukemogenesis and tumorigenesis and that miR-125a knockout mice overexpressed WT1 and developed myeloproliferative disease. It had been also reported that miR-125a is downregulated in leukemia and various types of solid tumors such as lung cancers, suggesting its tumor suppressor function. Therefore, it is important to elucidate what is target(s) of miR-125a for understandings of such functions although few target genes for it are known. In the present study, Zbtb7a oncogene was identified as a potential target for miR-125a by gene expression profiling in miR-125a knockout mice combined with bioinformatics target prediction. EGFP-3'UTR reporter assay showed that miR-125a suppressed Zbtb7a expression through its direct binding to the Zbtb7a-3'UTR. Zbtb7a knockdown by siRNA suppressed cell proliferation and induced G1 cell cycle arrest and apoptosis in lung cancer cells. Furthermore, miR-125a expression showed a negative correlation with Zbtb7a expression in non-small cell lung cancer tissues. The present study showed for the first time that Zbtb7a was a direct target for miR-125a and was involved in cell cycle progression and apoptosis of lung cancer cells. These results also demonstrated that deregulation of miR-125a-Zbtb7a signaling was associated with the development and progression of lung cancer. © 2015 Wiley Periodicals, Inc.

An Immunocompetent Mouse Model for MLL/AF9 Leukemia Reveals the Potential of Spontaneous Cytotoxic T-Cell Response to an Antigen Expressed in Leukemia Cells.

Leukemia differs substantially with respect to stromal milieu from tumors that progress locally as solid masses, and the physiological importance of immunosurveillance in leukemia remains unclear. However, currently available mouse leukemia models have critical limitations in the context of analyzing immunological regulation of leukemia development. In this study, we transferred mouse MLL/AF9 leukemia-initiating cells into immunocompetent recipient mice without any pre-conditioning such as irradiation, and then analyzed the spontaneous T cell response to an immunogenic antigen expressed in leukemia cells. When the minimum numbers of leukemia-initiating cells for engraftment were transferred, leukemia cells were eradicated by the adaptive immune response in most, if not all, wild-type mice, but not in Rag2-/- recipient mice, which lack adaptive immunity. By contrast, mice transplanted with larger numbers of leukemia cells always developed leukemia. In mice with advanced leukemia, antigen-specific CTLs were also expanded, but were unresponsive to antigen stimulation and expressed high levels of PD-1 and LAG-3. These results provide the first clear demonstration that the spontaneous CTL response to a tumor-cell antigen has the potential to eradicate leukemia, whereas antigen-specific CTLs are exhausted in animals with advanced leukemia. This immunocompetent mouse leukemia model provides a useful platform for developing effective immunotherapies against leukemia.

Identification of a Novel C-Terminal Truncated WT1 Isoform with Antagonistic Effects against Major WT1 Isoforms.

The Wilms' tumor gene WT1 consists of 10 exons and encodes a zinc finger transcription factor. There are four major WT1 isoforms resulting from alternative splicing at two sites, exon 5 (17AA) and exon 9 (KTS). All major WT1 isoforms are overexpressed in leukemia and solid tumors and play oncogenic roles such as inhibition of apoptosis, and promotion of cell proliferation, migration and invasion. In the present study, a novel alternatively spliced WT1 isoform that had an extended exon 4 (designated as exon 4a) with an additional 153 bp (designated as 4a sequence) at the 3' end was identified and designated as an Ex4a(+)WT1 isoform. The insertion of exon 4a resulted in the introduction of premature translational stop codons in the reading frame in exon 4a and production of C-terminal truncated WT1 proteins lacking zinc finger DNA-binding domain. Overexpression of the truncated Ex4a(+)WT1 isoform inhibited the major WT1-mediated transcriptional activation of anti-apoptotic Bcl-xL gene promoter and induced mitochondrial damage and apoptosis. Conversely, suppression of the Ex4a(+)WT1 isoform by Ex4a-specific siRNA attenuated apoptosis. These results indicated that the Ex4a(+)WT1 isoform exerted dominant negative effects on anti-apoptotic function of major WT1 isoforms. Ex4a(+)WT1 isoform was endogenously expressed as a minor isoform in myeloid leukemia and solid tumor cells and increased regardless of decrease in major WT1 isoforms during apoptosis, suggesting the dominant negative effects on anti-apoptotic function of major WT1 isoforms. These results indicated that Ex4a(+)WT1 isoform had an important physiological function that regulated oncogenic function of major WT1 isoforms.

Transduction of a novel HLA-DRB1*04:05-restricted, WT1-specific TCR gene into human CD4+ T cells confers killing activity against human leukemia cells.

BACKGROUND/AIM: Wilms' tumor gene 1 (WT1) product is a pan-tumor-associated antigen. We previously identified WT1 protein-derived promiscuous helper peptide, WT1332. Therefore, isolation and characterization of the WT1332-specific T-cell receptors (TCRs) are useful to develop broadly applicable TCR gene-based adoptive immunotherapy. MATERIALS AND METHODS: A novel HLA-DRB1*04:05-restricted WT1332-specific TCR gene was cloned and transduced into human CD4+ T-cells by using a lentiviral vector. RESULTS: The WT1332-specific TCR-transduced CD4+ T-cells showed strong proliferation and Th1-cytokine production in an HLA-DRB1*04:05-restricted, WT1332-specific manner. Furthermore, the WT1332-specific TCR-transduced CD4+ T-cells could lyse HLA-DRB1*04:05-positive, WT1-expressing leukemia cells in vitro. CONCLUSION: The novel TCR gene cloned here should be a promising tool to develop adoptive immunotherapy of WT1332-specific TCR-transduced CD4+ T-cells for the treatment of WT1-expressing cancer, such as leukemia.

Wilms' tumor gene WT1 promotes homologous recombination-mediated DNA damage repair.

The Wilms' tumor gene WT1 is overexpressed in leukemia and various types of solid tumors and plays an oncogenic role in these malignancies. Alternative splicing at two sites yields four major isoforms, 17AA(+)KTS(+), 17AA(+)KTS(-), 17AA(-)KTS(+), and 17AA(-)KTS(-), and all the isoforms are expressed in the malignancies. However, among the four isoforms, function of WT1[17AA(-)KTS(+)] isoform still remains undetermined. In the present study, we showed that forced expression of WT1[17AA(-)KTS(+)] isoform significantly inhibited apoptosis by DNA-damaging agents such as Doxorubicin, Mitomycin, Camptothesisn, and Bleomycin in immortalized fibroblast MRC5SV and cervical cancer HeLa cells. Knockdown of Rad51, an essential factor for homologous recombination (HR)-mediated DNA repair canceled the resistance to Doxorubicin induced by WT1[17AA(-)KTS(+)] isoform. GFP recombination assay showed that WT1[17AA(-)KTS(+)] isoform alone promoted HR, but that three other WT1 isoforms did not. WT1[17AA(-)KTS(+)] isoform significantly upregulated the expression of HR genes, XRCC2, Rad51D, and Rad54. Knockdown of XRCC2, Rad51D, and Rad54 inhibited the HR activity and canceled resistance to Doxorubicin in MRC5SV cells with forced expression of WT1[17AA(-)KTS(+)] isoform. Furthermore, chromatin immunoprecipitation (ChIP) assay showed the binding of WT1[17AA(-)KTS(+)] isoform protein to promoters of XRCC2 and Rad51D. Immunohistochemical study showed that Rad54 and XRCC2 proteins were highly expressed in the majority of non-small-cell lung cancer (NSCLC) and gastric cancer, and that expression of these two proteins was significantly correlated with that of WT1 protein in NSCLCs. Our results presented here showed that WT1[17AA(-)KTS(+)] isoform had a function to promote HR-mediated DNA repair.

The translation elongation factor eEF2 is a novel tumor­associated antigen overexpressed in various types of cancers.

Recent studies have shown that cancer immunotherapy could be a promising therapeutic approach for the treatment of cancer. In the present study, to identify novel tumor-associated antigens (TAAs), the proteins expressed in a panel of cancer cells were serologically screened by immunoblot analysis and the eukaryotic elongation factor 2 (eEF2) was identified as an antigen that was recognized by IgG autoantibody in sera from a group of patients with head and neck squamous cell carcinoma (HNSCC) or colon cancer. Enzyme-linked immunosorbent assay showed that serum eEF2 IgG Ab levels were significantly higher in colorectal and gastric cancer patients compared to healthy individuals. Immunohistochemistry experiments showed that the eEF2 protein was overexpressed in the majority of lung, esophageal, pancreatic, breast and prostate cancers, HNSCC, glioblastoma multiforme and non-Hodgkin's lymphoma (NHL). Knockdown of eEF2 by short hairpin RNA (shRNA) significantly inhibited the growth in four eEF2-expressing cell lines, PC14 lung cancer, PCI6 pancreatic cancer, HT1080 fibrosarcoma and A172 glioblastoma cells, but not in eEF2-undetectable MCF7 cells. Furthermore, eEF2-derived 9-mer peptides, EF786 (eEF2 786-794 aa) and EF292 (eEF2 292-300 aa), elicited cytotoxic T lymphocyte (CTL) responses in peripheral blood mononuclear cells (PBMCs) from an HLA-A*24:02- and an HLA-A*02:01-positive healthy donor, respectively, in an HLA-A-restricted manner. These results indicated that the eEF2 gene is overexpressed in the majority of several types of cancers and plays an oncogenic role in cancer cell growth. Moreover, the eEF2 gene product is immunogenic and a promising target molecule of cancer immunotherapy for several types of cancers.

HLA-DPB1*05: 01-restricted WT1332-specific TCR-transduced CD4+ T lymphocytes display a helper activity for WT1-specific CTL induction and a cytotoxicity against leukemia cells.

Wilms tumor gene 1 (WT1) is overexpressed in various malignant neoplasms, and has been demonstrated as an attractive target for cancer immunotherapy. We previously reported the identification of a WT1 protein-derived, 16-mer helper peptide WT1332 that could elicit Th1-type CD4+ T-cell response and bind to multiple HLA class II molecules. In this study, we examined the feasibility of adoptive therapy using CD4+ T cells that were transduced an HLA-DPB1*05:01-restricted, WT1332-specific T-cell receptor (TCR). HLA-DPB1*05:01-restricted, WT1332-specific TCR-transduced CD4+ T cells were successfully generated using lentiviral vector and exhibited strong proliferative response and Th1-type cytokine production in response to WT1332 peptide, WT1 protein, or WT1-expressing tumor cell lysate. Furthermore, the WT1332-specific TCR-transduced CD4+ T cells lysed HLA-DPB1*05:01-positive, WT1-expressing human leukemia cells through granzyme B/perforin pathway. Furthermore, stimulation of peripheral blood mononuclear cells with both HLA-A*24:02-restricted cytotoxic T lymphocytes-epitope peptide (modified 9-mer WT1235 peptide, WT1235m) and WT1332 helper peptide in the presence of WT1332-specific TCR-transduced CD4+ T cells strikingly enhanced the induction of WT1235m-specific cytotoxic T lymphocytes. Thus, these results demonstrated the feasibility of immunotherapy based on adoptive transfer of WT1332-specific TCR-transduced CD4+ T cells for the treatment of leukemia.

Enhanced tumor immunity of WT1 peptide vaccination by interferon-ß administration.

To induce and activate tumor-associated antigen-specific cytotoxic T lymphocytes (CTLs) for cancer immunity, it is important not only to select potent CTL epitopes but also to combine them with appropriate immunopotentiating agents. Here we investigated whether tumor immunity induced by WT1 peptide vaccination could be enhanced by IFN-ß. For the experimental group, C57BL/6 mice were twice pre-treated with WT1 peptide vaccine, implanted with WT1-expressing C1498 cells, and treated four times with WT1 peptide vaccine at one-week intervals. During the vaccination period, IFN-ß was injected three times a week. Mice in control groups were treated with WT1 peptide alone, IFN-ß alone, or PBS alone. The mice in the experimental group rejected tumor cells and survived significantly longer than mice in the control groups. The overall survival on day 75 was 40% for the mice treated with WT1 peptide+IFN-ß, while it was 7, 7, and 0% for those treated with WT1 peptide alone, IFN-ß alone or PBS alone, respectively. Induction of WT1-specific CTLs and enhancement of NK activity were detected in splenocytes from mice in the experimental group. Furthermore, administration of IFN-ß enhanced expression of MHC class I molecules on the implanted tumor cells. In conclusion, our results showed that co-administration of WT1 peptide+IFN-ß enhanced tumor immunity mainly through the induction of WT1-specific CTLs, enhancement of NK activity, and promotion of MHC class I expression on the tumor cells. WT1 peptide vaccination combined with IFN-ß administration can thus be expected to enhance the clinical efficacy of WT1 immunotherapy.

A clear correlation between WT1-specific Th response and clinical response in WT1 CTL epitope vaccination.

Clinical studies of WT1-targeted cancer vaccine are being performed. However, WT1-specific Th response in cancer patients remains unclear. Using quantitative real-time RT-PCR, we investigated IFN-gamma and IL-10 mRNA expression from Th cells by stimulation with helper peptide WT1(332). Seventeen patients, of whom 10 had achieved stable disease and the remaining 7 had progressive disease, were weekly vaccinated with WT1 CTL epitope (modified WT1(235)) and examined for WT1(332)-specific Th response. A clear correlation between WT1(332)-specific Th response and clinical response was observed at 4 weeks post-vaccination. In patients who responded, a clear inverse correlation between IL-10-type and IFN-gamma-type WT1(332)-specific Th response was detected at pre- and 4 weeks post-vaccination, and the shift of the Th response from IL-10-type dominancy at early phase to IFN-gamma-type dominancy at late phase was observed. From this study we concluded that occurrence of WT1(332)-specific Th response could predict good clinical response of WT1 CTL epitope vaccination.

One-dimensional alignment of SBA-15 films in microtrenches.

SBA-15 thin films were synthesized by dip-coating in two different types of microtrenches: (a) silicon microtrenches and (b) silicon microtrenches with a deposited low-temperature oxide (LTO) layer. In the upper part of the synthesized films, the pores were aligned along the concave surface in both microtrenches. This alignment was attributed to the capillary force acting during solvent evaporation. In the lower part of the films, the pores were aligned tangentially with the wall in a silicon microtrench whereas they were aligned normal to the wall in a silicon microtrench with a deposited LTO layer. The LTO layer could suppress the growth of mesostructures from the substrate and promote growth from the vapor-liquid interface. The effects of the composition of the precursor solution and relative humidity on pore alignment were also clarified.

Overexpression of eukaryotic elongation factor eEF2 in gastrointestinal cancers and its involvement in G2/M progression in the cell cycle.

A high level protein synthesis is one of the characteristics of cancer cells. The aim of this study is to show the contribution of eukaryotic elongation factor 2 (eEF2), which plays an essential role in the polypeptide chain elongation step, in the tumorigenesis of gastrointestinal cancers. In the present study, we demonstrated by using immunohistochemistry that eEF2 protein was overexpressed in 92.9% (13 of 14) of gastric and 91.7% (22 of 24) of colorectal cancers. No mutations were found in any of the exons of the eEF2 gene in six gastric and six colorectal cancers. Knockdown of eEF2 by eEF2-specific short-hairpin RNA (shEF2) inhibited cancer cell growth in two gastric cancer cell lines, AZ-521 and MKN28, and one colon cancer cell line, SW620. Flow cytometric analysis showed that knockdown of eEF2 induced G2/M arrest and resulted in inactivation of Akt and cdc2 (a G2/M regulator) and activation of eEF2 kinase (a negative regulator of eEF2) in these cancer cells. Conversely, forced expression of eEF2 in AZ-521 cells significantly enhanced the cell growth through promotion of G2/M progression in cell cycle, activated Akt and cdc2, and inactivated eEF2 kinase. Furthermore, forced expression of eEF2 in these cancer cells enhanced in vivo tumorigenicity in a mouse xenograft model. These results showed that overexpressed eEF2 in gastrointestinal cancers promoted G2/M progression and enhanced their cell growth in vitro and in vivo. These results also suggested a novel linkage between translational elongation and cell cycle mechanisms, implying that the linkage might play an important role to orchestrate the deregulated translation and cell cycle mechanisms for promotion of the development of gastrointestinal cancers.

WT1 IgG antibody for early detection of nonsmall cell lung cancer and as its prognostic factor.

There are urgent needs to develop methods for early detection of nonsmall cell lung cancer (NSCLC) because of its increasing incidence and poor prognosis. Here, we analyzed the production of IgG antibody (WT1 Ab) against WT1 (Wilms' tumor gene) protein that was overexpressed in the majority of NSCLC. Enzyme-linked immuno-sorbent assay showed that WT1 Ab was produced in all of 91 NSCLC patients and 70 healthy individuals and that WT1 Ab titers were significantly higher in NSCLC patients compared with healthy individuals. When the cut-off level of WT1 Ab titers were fixed at mean + 3SD of those in healthy individuals, 26.4% of NSCLC patients had WT1 Ab titers over the cut-off level, and positive rates of WT1 Ab at each clinical stage were 25.0, 30.8 and 38.4% in stage I, II and III NSCLC, respectively. When WT1 Ab was combined with CEA or CYFRA for detection of NSCLC, positive detection rates increased from 25.0 to 34.1 and 31.8%, respectively, in stage I and from 38.4 to 69.2 and 46.1%, respectively, in stage III, but not changed in stage II. Western blot analysis showed that dominant subclass of WT1 Ab was Th1-type IgG2. Interestingly, elevation of WT1 Ab titers was significantly associated with longer disease-free survival in patients with stages I-III NSCLC. These results showed that WT1 Ab could be a useful marker for early detection of NSCLC and its prognostic prediction. These results also suggested that WT1-specific immune responses played an important role in anti-cancer immunity in NSCLC.