Identification of a new cancer/germline gene, KK-LC-1, encoding an antigen recognized by autologous CTL induced on human lung adenocarcinoma

Antitumor activity of human γδ T cells transducted with CD8 and with T-cell receptors of tumor-specific cytotoxic T lymphocytes

The difficulty in the induction and preparation of a large number of autologous tumor-specific cytotoxic T lymphocytes (CTL) from individual patients is one of major problems in their application to adoptive immunotherapy. The present study tried to establish the useful antitumor effectors by using γδ T cells through tumor-specific TCRαβ genes transduction, and evaluated the efficacy of their adoptive transfer in a non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice model. The TCRαβ gene was cloned from the HLA-B15-restricted CTL clone specific of the Kita-Kyushu Lung Cancer antigen-1 (KK-LC-1). The cloned TCRαβ as well as the CD8 gene were transduced into γδ T cells induced from peripheral blood lymphocytes (PBL). Cytotoxic T lymphocyte activity was examined using a standard 4 h (51) Cr release assay. Mice with a xenotransplanted tumor were treated with an injection of effector cells. Successful transduction of TCRαβ was confirmed by the staining of KK-LC-1-specific tetramers. The γδ T cells transduced with TCRαβ and CD8 showed CTL activity against the KK-LC-1-positive lung cancer cell line in a HLA B15-restricted manner. Adoptive transfer of the effector cells in a mice model resulted in marked growth suppression of KK-LC-1- and HLA-B15-positive xenotransplanted tumors. Co-transducing TCRαβ and CD8 into γδ T cells yielded the same antigen-specific activity as an original CTL in vitro and in vivo. The TCRαβ gene transduction into γδ T cells is a promising strategy for developing new adoptive immunotherapy.

Identification of a lung cancer antigen evading CTL attack due to loss of human leukocyte antigen (HLA) class I expression

The human lung cancer cell line, C831L, lost HLA class I expression due to a mutation of the β2-microglobulin (β2m) gene, and it may have been the result of immunoediting by CTL cytotoxicity. By restoration of HLA class I expression, we could identify the antigen that may be associated with HLA downregulation. Such an antigen might be a promising target of immunotherapy because it potentially may induce a sufficient immune response to eradicate cancer cells. The CTL clone could be established from lymph node lymphocytes in patient C831 by stimulation with wild-type β2m-transduced C831L (C831L-wβ2m). The CTL clone showed reactivity against C831L-wβ2m in a HLA-B*0702-restricted manner, but not Parental-C831L or autologous normal cells. The cDNA expression cloning method was used to identify the antigen coding gene recognized by the CTL clone. The cDNA clone exhibited a homology with a part of the mRNA that codes for leucine rich repeat containing eight family member A (LRRC8A). A transfection analysis of minigenes indicated that the antigen peptide was derived from protein translated from the downstream of the registered open reading frame in LRRC8A mRNA. The antigenic 9-mer peptide (GPRESRPPA) was identified. The present methodology should be useful to find the crucial tumor antigens, which are potentially associated with loss of HLA expression. Furthermore, such an antigen may help in achieving a better understanding of the immunological escape mechanisms and it may also provide a favorable immune response in cancer immunotherapy.

Identification of ribosomal protein L19 as a novel tumor antigen recognized by autologous cytotoxic T lymphocytes in lung adenocarcinoma

The purpose of the present study was to identify a novel tumor-specific antigen capable of inducing a specific cellular immune response in lung cancer patients. The co-culture of regional lymph node lymphocytes and the CD80-transfected autologous lung adenocarcinoma cell line H1224L resulted in a successful induction of bulk cytotoxic T lymphocytes (CTL). CTL clone L7/8 was established by the limiting dilution method from these bulk CTLs and lysed H1224L but not autologous Epstein-Barr virus-transformed B cells or K562. The CTL clone also recognized allogeneic lung cancer cell lines in an HLA-A*31012-restricted manner. Using the CTL clone, an antigen-coding gene was identified using the cDNA expression cloning technique, which encodes ribosomal protein L19 (RPL19). Finally, a 9 mer antigenic peptide was identified by means of construction of mini-genes. RPL19 was overexpressed in the lung cancer tissue from patient H1224. All of the normal tissues examined expressed lower levels of RPL19 mRNA than that of the lung cancer tissue. RPL19 was also found to be overexpressed in 12 of 30 (40%) non-small-cell lung cancer tissues by immunohistochemical staining. The expression level of RPL19 in tumor cell lines correlated positively with the production of interferon (IFN)-gammaby CTL clone L7/8 in response to such cell lines. In addition, the suppression of RPL19 expression by transfection with small interfering RNA resulted in the suppression of cyclinD1, D3 synthesis, and the growth inhibition of lung cancer cell lines overexpressing RPL19. Therefore, this growth suppression could be ascribed to the inhibition of the cell cycle. These results may indicate that RPL19 is a novel overexpressed antigen which may therefore be a useful candidate as a target for specific immunotherapy.

Cancer/testis (CT) antigens: potential targets for immunotherapy

Cancer/testis (CT) antigens are protein antigens with normal expression restricted to adult testicular germ cells, and yet are aberrantly activated and expressed in a proportion of various types of human cancer. At least a subset of this group of antigens has been found to elicit spontaneous humoral and cell-mediated immune responses in cancer patients, raising the possibility that these antigens could be cancer vaccine targets. More than 100 CT antigen genes have been reported in the literature, with approximately 30 being members of multigene families on the X chromosome, so-called CT-X genes. Most CT-X genes are expressed at the spermatogonia stage of spermatogenesis, and their functions are mostly unknown. In cancer, the frequency of CT antigen expression is highly variable among different tumor types, but is more often expressed in high-grade late-stage cases in general. Cancer vaccine trials based on CT antigens MAGE-A3 and NY-ESO-1 are currently ongoing, and these antigens may also play a role in antigen-specific adoptive T-cell transfer and in the immunomodulation approach of cancer therapy.

Clinical significance of cancer/testis antigens expression in patients with non-small cell lung cancer

Cancer/testis antigens (CT antigens) are thought to be suitable targets for antigen-specific immunotherapy, because of the cancer-specific expression except for the testis among various normal tissues and no-expression of HLA class I in the testis. In the present study, the expressions of CT antigens (MAGE-A3, MAGE-A4, NY-ESO-1 and KK-LC-1) in non-small cell lung cancer (NSCLC) were analyzed by RT-PCR. The subjects were 239 patients with NSCLC who underwent surgery from 2001 to 2005 in our department. The expression rates of MAGE-A3, MAGE-A4, NY-ESO-1 and KK-LC-1 were 23.8%, 20.1%, 10.5% and 32.6% in patients with NSCLC, respectively. MAGE-A4 was expressed more frequently in male (25.3%) than in female (10.6%) (p<0.01). The positive proportion of MAGE-A4 was higher in stages II-IV (30.6%) than in stage I (12.8%) (p<0.01). Both of MAGE-A3 and MAGE-A4 were expressed more frequently in squamous cell carcinoma than in adenocarcinoma (p<0.01). Such tendency was not observed among NY-ESO-1 and KK-LC-1 expression. KK-LC-1 was expressed in 32.1% of patients with adenocarcinoma and in 36.5% of patients with squamous cell carcinoma. Patients with positive MAGE-A4 expression showed significantly poorer overall survival than those without MAGE-A4 expression (p=0.013), and such effect on survival was also observed, when the analysis was limited to patients at stage I (p=0.0037). Expression of MAGE-A3, NY-ESO-1 or KK-LC-1 did not affect survival of patients with NSCLC significantly, however, expression of at least one of such CT antigens negatively affect survival of patients with NSCLC (p=0.045).

Regulated expression of a tumor-associated antigen reveals multiple levels of T-cell tolerance in a mouse model of lung cancer

Maximizing the potential of cancer immunotherapy requires model systems that closely recapitulate human disease to study T-cell responses to tumor antigens and to test immunotherapeutic strategies. We have created a new system that is compatible with Cre-LoxP-regulatable mouse cancer models in which the SIY antigen is specifically overexpressed in tumors, mimicking clinically relevant TAAs. To show the utility of this system, we have characterized SIY-reactive T cells in the context of lung adenocarcinoma, revealing multiple levels of antigen-specific T-cell tolerance that serve to limit an effective antitumor response. Thymic deletion reduced the number of SIY-reactive T cells present in the animals. When potentially self-reactive T cells in the periphery were activated, they were efficiently eliminated. Inhibition of apoptosis resulted in more persistent self-reactive T cells, but these cells became anergic to antigen stimulation. Finally, in the presence of tumors overexpressing SIY, SIY-specific T cells required a higher level of costimulation to achieve functional activation. This system represents a valuable tool in which to explore sources contributing to T-cell tolerance of cancer and to test therapies aimed at overcoming this tolerance.

Clinical significance of HLA class I alleles on postoperative prognosis of lung cancer patients in Japan

BACKGROUND

The role of the HLA phenotype in cancer prognosis has been frequently discussed. We previously reported the correlation between HLA alleles and the postoperative prognosis of 204 patients with non-small cell lung cancer (NSCLC). The present study was based on 695 patients with NSCLC to confirm these correlations.

METHODS

We evaluated the medical records of 695 NSCLC patients who underwent surgical resection. The serological typing of HLA class I was performed using a microcytotoxicity test of lymphocytes or PCR-sequence-specific oligonucleotides (PCR-SSO), and the correlation between the HLA alleles and the clinicopathological features was analyzed. The survival curves were calculated, and then a comparison of the survival curves was carried out.

RESULTS

The HLA-A2 positive(A2(+)) group at stage I showed a more unfavorable prognosis than HLA-A2(-) group in overall survival. At stage II+III, the HLA-A24(+) group had a poorer prognosis than the HLA-A24(-) group, and the HLA-B52(+) group showed unfavorable prognosis. Multivariate analysis demonstrated that HLA-A2 at stage I and HLA-A24 at stage II+III were the independent factors that affected the survival period.

CONCLUSIONS

The expression of HLA-A2 was considered as one of the unfavorable prognostic factors in the NSCLC patients at stage I. HLA-A24(+) group showed a significant unfavorable prognosis at stage II+III. These results suggested that HLA-A2 and HLA-A24 could be the prognostic factors in patients with NSCLC according to the state of advancement of the disease.

Immune modulation as a therapeutic strategy for non-small-cell lung cancer

Active tumor immunotherapy may provide hope for patients with non-small-cell lung cancer (NSCLC) because, in more than 20 years, current therapies have yet to change mortality statistics. Creating an efficacious vaccine involves selection of important tumor antigens and formulation of their immunogenic epitopes into a construct for delivery to antigen-presenting cells. The method of immunization will confer significant properties to the potency of the vaccine and might require augmentation with certain adjuvant agents like interleukin-12 and granulocyte-macrophage colony-stimulating factor. So far, clinical trials in NSCLC immunotherapy have shown promise with the Induction of Immune responses and the presence of clinical responses compared with historical controls treated with standard therapy. Immunotherapy could merge seamlessly into the current standard of care for NSCLC with the emergence of data supporting a beneficial role of chemotherapy and radiation in the production of antitumor immune responses. With continued work in this field, active immunotherapy may provide the necessary therapy for the successful treatment of this common disease.

Lack and restoration of sensitivity of lung cancer cells to cellular attack with special reference to expression of human leukocyte antigen class I and/or major histocompatibility complex class I chain related molecules A/B

Both cytotoxic T lymphocytes (CTL) and natural killer (NK) cells may play major roles in the host defense against cancer. However, their relationship against the same tumor remains to be elucidated. Among 26 human lung cancer cell lines established in our laboratory, 10 (38%) exhibited human leukocyte antigen (HLA)-class I haplotype loss and three (12%) lost HLA-class I expression totally by flow cytometry analysis. The two cell lines (E522L and C831L) that lost their expression of HLA-class I in vitro and in vivo were applied for further evaluations. Genetic abnormalities of beta2-microglobulin gene were observed in both E522L (loss of mRNA) and C831L (point mutation). Transduction of the wild-type beta2-microglobulin gene rendered them positive for HLA-class I expression. The CTL were induced from autologous peripheral blood mononuclear cells or regional lymph node lymphocytes by stimulation with wild-type beta2-microglobulin transduced-E522L or -C831L, and they showed tumor-specific cytotoxicity against wild-type beta2-microglobulin-transductant, but not parental cells. In NK cell cytotoxicity, E522L showed high sensitivity to NK cells; however, C831L showed resistance despite loss of HLA-class I expression. E522L expressed MHC class I chain related molecules A/B, but C831L did not. The transduction of the MHC class I chain related molecule A gene from E522L rendered C831L positive for expression and sensitive to NK cell cytotoxicity. Reconstruction of HLA-class I and MHC class I chain related molecules A expression could abrogate evasion from cellular attack by CTL and NK cells, and it may lead to a breakthrough in the development of cancer immunotherapy.

Receptor-Mediated Delivery of Antigens to Dendritic Cells: Anticancer Applications

Recently, there has been a surge of interest in the use of ex vivo antigen-pulsed dendritic cells (DCs) in the immunotherapy for cancer. DCs are powerful adjuvants with the ability to prime naive CD4+ and CD8+ T cells. As antigen sources, various preparations, including peptides, proteins, crude tumor lysates, and DCs transfected or transformed with various viruses, have been used. These procedures that involve the isolation of patient DCs and reintroduction after in vitro manipulation are time-consuming and expensive. The DC populations used frequently in ex vivo clinical studies are IL-4 and GM-CSF cultured DCs that may not represent the in vivo DC populations. An attractive method of targeting in vivo DCs is to utilize various ligands or antibodies that bind discrete populations of DCs. These cell surface receptors will direct the antigen to different antigen processing pathways depending on the targeted receptor to induce cytotoxic T cell or T helper responses. This review will discuss the various approaches and receptors that have been used for antigen targeting that may eventually be translated to alternative DC-based immunotherapies.