Lung Cancer Antigen Research Articles

Prognostic Value of CYFRA 21-1 and Carcinoembryonic Antigen in Non-Small Cell Lung Cancer

Background: The diagnostic value of serum tumor markers, such as cytokeratin 19 fragment (CYFRA 21-1) and carcino embryonic antigen (CEA) in non-small cell lung cancer (NSCLC) has been established. Only few studies have focused on the prognostic values of these two markers. Objective: This study was designed to verify the prognostic significance of serum CYFRA 21-1 and CEA assay in patients with NSCLC. Methods: The study population comprised of 40 patients of NSCLC (30 males and 10 females) with a mean age of 62.3yrs. Out of forty, twenty two had an adenocarcinoma and 18 had squamous cell carcinoma. Seven patients were at stage II, 24 were at stage III and 9 were at stage IV. None of the patients received any previous treatment. Chest computed tomography (CT) scan was done on baseline and every 2 months frequency to assess the objective radiological response. Twice serum samples were collected, initial collection was done before the beginning of treatment and the other collection was done after the second cycle of first line chemotherapy. Analysis was performed for CYFRA 21-1 and CEA using an enzyme immunoassay (EIA). Fifteen healthy volunteers with similar age and sex as the study population were selected and were used as a control group. Results: The study revealed that 80. 8% sensitivity was observed both for CYFRA 21-1 and CEA as a predictor of favourable radiological response. The cut-off values used were 10.40 ng/ml for CYFRA 21-1 and 9.30 ng/ml for CEA respectively. Univariate regression analysis identified 3 fold improved survival for the patients with post treatment CYFRA 21-1<10.4 ng/ml (P=0.001) and CEA <9.3 (P=0.001). Performance status <2 (P=0.01)) and an early stage of NSCLC (P=0.03) were also found as significant independent factors associated with improved survival. Conclusion: Comparable satisfactory results were found for both CYFRA 21-1 and CEA after 2 cycles of chemotherapy as prognostic markers for radiological response and survival outcomes in NSCLC.

Novel antigens in non-small cell lung cancer: SP17, AKAP4, and PTTG1 are potential immunotherapeutic targets.

Lung cancer is the leading cause of cancer deaths in both genders worldwide, with an incidence only second to prostate cancer in men and breast cancer in women. The lethality of the disease highlights the urgent need for innovative therapeutic options. Immunotherapy can afford efficient and specific targeting of tumor cells, improving efficacy and reducing the side effects of current therapies. We have previously reported the aberrant expression of cancer/testis antigens (CTAs) in tumors of unrelated histological origin. In this study we investigated the expression and immunogenicity of the CTAs, Sperm Protein 17 (SP17), A-kinase anchor protein 4 (AKAP4) and Pituitary Tumor Transforming Gene 1 (PTTG1) in human non-small cell lung cancer (NSCLC) cell lines and primary tumors. We found that SP17, AKAP4 and PTTG1 are aberrantly expressed in cancer samples, compared to normal lung cell lines and tissues. We established the immunogenicity of these CTAs by measuring CTA-specific autoantibodies in patients' sera and generating CTA-specific autologous cytotoxic lymphocytes from patients' peripheral blood mononuclear cells. Our results provide proof of principle that the CTAs SP17/AKAP4/PTTG1 are expressed in both human NSCLC cell lines and primary tumors and can elicit an immunogenic response in lung cancer patients.

A search for novel cancer/testis antigens in lung cancer identifies VCX/Y genes, expanding the repertoire of potential immunotherapeutic targets.

Cancer/testis (CT) antigens are potential immunotherapeutic targets in cancer. However, the expression of particular antigens is limited to a subset of tumors of a given type. Thus, there is a need to identify antigens with complementary expression patterns for effective therapeutic intervention. In this study, we searched for genes that were distinctly expressed at a higher level in lung tumor tissue and the testes compared with other nontumor tissues and identified members of the VCX/Y gene family as novel CT antigens. VCX3A, a member of the VCX/Y gene family, was expressed at the protein level in approximately 20% of lung adenocarcinomas and 35% of squamous cell carcinomas, but not expressed in normal lung tissues. Among CT antigens with concordant mRNA and protein expression levels, four CT antigens, XAGE1, VCX, IL13RA2, and SYCE1, were expressed, alone or in combination, in about 80% of lung adenocarcinoma tumors. The CT antigen VCX/Y gene family broadens the spectrum of CT antigens expressed in lung adenocarcinomas for clinical applications.

Prognostic significance of preoperative serum carcinoembryonic antigen in non-small cell lung cancer: a meta-analysis.

Observational studies on the prognostic role of preoperative serum carcinoembryonic antigen (CEA) in non-small cell lung cancer (NSCLC) are controversial. Electronic databases updated until June 1, 2014 were searched to find relevant studies. A meta-analysis was conducted with eligible studies which quantitatively evaluated the relationship between preoperative serum CEA level and survival of patients with NSCLC. Survival data were aggregated and quantitatively analyzed. We performed a meta-analysis of 16 studies (n = 4,296 patients) that evaluated the correlation between preoperative serum CEA level and survival in patients with NSCLC. Combined hazard ratios suggested that preoperative serum CEA overexpression was associated with poor prognosis of overall survival (OS) (hazard ratio (HR) = 2.28, 95 % confidence interval (CI) 2.24-2.31) in patients with NSCLC. Meanwhile, for p-stage I NSCLC, the HR (95 % CI) was 1.98 (1.73-2.15). In the stratified analysis by patient source, significant risks were found among Asians and non-Asians. However, significant heterogeneity was observed among all studies. In the present meta-analysis, preoperative serum CEA overexpression indicates a poor prognosis for patients with NSCLC.

Auto-antibody profiling with over 9,500 human expressed proteins (TECH1P.853)

Abstract Autoantibody profiling is a powerful method to probe the immune system for early signs of disease. However, progress has been limited by the availability of suitable antigens and high-throughput tools for screening large numbers of samples. Most antigens available have been produced in bacterial or insect cells and thus may not be optimal for autoantibody profiling. Although protein microarrays have been widely used to identify common autoantibodies in many diseases, creating smaller panels of antigens for larger screening studies has been difficult and costly. We have developed rapid methods for coupling proteins to Luminex beads allowing us to create and validate focused beads arrays in just a few days using native human proteins that have been expressed and purified in HEK293 cells. We have also developed a variable-stringency assay system that allows the user to optimize the detection specificity according to their particular application. Internal and external controls validate the presence of each protein and the IgG from the patient sample. Bead arrays for classic autoimmune antigens, as well as human breast, prostate, ovarian, pancreatic and lung cancer antigens have been prepared and custom arrays can be prepared from any of OriGene’s over 9500 purified proteins. Preliminary results with serum samples from traditional autoimmune patients, breast cancer, and Type II Diabetes support the utility of the approach.

Knockdown of CABYR-a/b Increases Chemosensitivity of Human Non–Small Cell Lung Cancer Cells through Inactivation of Akt

CABYR is a calcium-binding tyrosine phosphorylation-regulated protein that was identified as a novel cancer testis antigen in lung cancer in our previous study. However, the role of CABYR as a driver of disease progression or as a chemosensitizer is poorly understood. This study sought to investigate the relationship between the expression levels of CABYR-a/b, which are the two predominant isoforms of the five isoform proteins encoded by CABYR, and chemosensitivity in non-small cell lung cancer cells. We found that the short hairpin RNA-mediated knockdown of CABYR-a/b significantly inhibited the proliferation of NCI-H460 and A549 cells and resulted in the attenuation of Akt phosphorylation, which is constitutively active in lung cancer cells. The silencing of CABYR-a/b expression notably impacted the downstream components of the Akt pathways: decreasing the phospho-GSK-3β (Ser9) levels and increasing the expression of the p53 and p27 proteins. Furthermore, CABYR-a/b knockdown led to a significant increase in chemosensitivity in response to chemotherapeutic drugs and drug-induced apoptosis, both in vitro and in vivo. Conversely, the transient transfection of CABYR-a/b-depleted cells with constitutively active Akt partially restored the resistance to cisplatin and paclitaxel and significantly decreased the activation of GSK-3β and cleaved PARP. Taken together, our results suggest that the inhibition of CABYR-a/b is a novel method to improve the apoptotic response and chemosensitivity in lung cancer and that this cancer testis antigen is an attractive target for lung cancer drug development. Suppression of CABYR-a/b expression increases chemosensitivity of lung cancer cells by inhibiting Akt activity.

Abstract B24: A systematic search for cancer/testis antigens in lung cancer identifies VCX/Y genes expanding the repertoire of potential immunotherapeutic targets.

Abstract Background: A wide range of therapeutic cancer vaccines that target diverse tumor-associated antigens are currently been evaluated in early phase clinical trials. However the effectiveness of cancer vaccines is so far limited, potentially due in part to the limited availability of candidate targets with broad expression in a tumor type. Cancer/testis (CT) antigens are a major target of cancer vaccines, because CT antigens are specifically expressed in immune-privileged testis and placenta, and exhibit aberrant expression in various types of cancer, resulting in high immunogenicity with no self-tolerance and reduced adverse effects. However expression of particular antigens is limited to a subset of tumors of a given type. Thus there is a need to identify antigens with complementary expression patterns for more effective therapeutic intervention. Methods: Gene expression data of BioGPS, and DNA methylation and RNA-seq data of TCGA lung cancer samples were downloaded. All lung cancer cell lines were cultured in RPMI1640 containing 10% FBS. A total of 83 pairs of treatment naive lung adenocarcinoma tissues and adjacent non-tumor lung tissues had been obtained earlier with informed consent. Gene expression data for cell lines and tissues were obtained using the Illumina Human WG-6 v3.0 Expression BeadChips. For mass spectrometric analysis, 38 non-small cell lung cancer (NSCLC) cell lines were cultured according to the standard SILAC protocol. The same batch of cells was used for analysis of whole cell extract, conditioned media and cell surface proteins. Tissue microarrays comprised 463 surgically resected NSCLC tumor specimens collected under an IRB protocol. Monoclonal anti-mouse VCX3A antibody was used for Western blot and immunohistochemistry analysis. Results: With mining the public database BioGPS, we identified VCX/Y gene family as novel CT antigens in lung cancer. Our findings also suggested epigenetic regulation of VCX/Y gene expression, and potential oncogenic roles of VCX/Y genes. Expression of one of the VCX/Y family genes, VCX3A, was further confirmed at the protein level in ~20% of lung adenocarcinoma and ~35% of squamous cell carcinoma tumors. We further examined gene expression patterns of CT antigens to determine whether a panel could be assembled with broad representation in lung adenocarcinoma. Of 255 known CT antigens, 109 CT antigens were profiled at both mRNA and protein levels in 38 NSCLC cell lines. mRNA expression levels of 10 CT antigens were significantly and positively correlated with protein expression levels. We examined mRNA expression profiles of these 10 CT antigens, together with VCX and MAGEA3 which is a current target for vaccine immunotherapy, in 83 lung adenocarcinoma tumors. We selected XAGE1, VCX, IL13RA2, and SYCE1 to form a CT antigen panel and compared mRNA expression levels of these four genes between tumor and adjacent non-tumor tissue. One or more of the CT antigens in the panel were overexpressed in 66 (79.5%) of lung adenocarcinomas. Conclusions: The present study identifies for the first time a novel CT antigen VCX/Y gene family in lung cancer. A CT antigen panel was found to provide a broad coverage of lung adenocarcinoma tumors tested, suggestive of a potential for more effective immunotherapy through targeting the combined antigen panel compared to a single antigen target. Citation Format: Ayumu Taguchi, Allen D. Taylor, Jaime Rodriguez, Muge Celiktas, Hui Liu, Xiaotu Ma, Qing Zhang, Chee-Hong Wong, Alice Chin, Luc Girard, Carmen Behrens, Wan Lam, Stephen Lam, John D. Minna, Ignacio I. Wistuba, Adi F. Gazdar, Samir M. Hanash. A systematic search for cancer/testis antigens in lung cancer identifies VCX/Y genes expanding the repertoire of potential immunotherapeutic targets. [abstract]. In: Proceedings of the AACR-IASLC Joint Conference on Molecular Origins of Lung Cancer; 2014 Jan 6-9; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2014;20(2Suppl):Abstract nr B24.

Expression and prognostic relevance of tumor carcinoembryonic antigen in stage IB non-small cell lung cancer.

High serum carcinoembryonic antigen (CEA) levels have been reported to be associated with poor prognosis in non-small cell lung cancer (NSCLC), while the prognostic role of tumor CEA expression remains to be defined. The present study investigated the expression of tumor CEA in stage IB NSCLC, and correlated it with clinicopathological features and prognosis. Immunohistochemistry for tumor CEA was assessed in the specimens of 183 patients with stage IB NSCLC. Receiver-operating characteristic (ROC) curve analysis was used to determine the cut-off score for tumor positivity. High CEA expression was detected more frequently in adenocarcinomas (72.2%) and other NSCLCs (69.0%) than in squamous cell carcinomas (25.4%, P<0.001). Both univariate and multivariate analysis indicated that tumor CEA was an independent prognostic factor for overall and disease-free survival (P<0.05). Elevated expression of tumor CEA may be an adverse prognostic indicator in stages IB NSCLC.

Abstract LB-108: Racotumomab antitumor activity in the murine model of non small cell lung carcinoma 3LL is related with the level of expression on NGcGM3

Abstract N-Glycolylneuraminic acid (NGc) is a sialic acid molecule found in most mammalian cells. It is usually found as terminal constituents of different membrane glycoconjugates such as the GM3 ganglioside (NGcGM3) and has been described as tumor antigen in non small cell lung cancer (NSCLC) in humans. However, most mouse cancer cell lines, such as 3LL NSCLC, are negative for the expression of this antigen although mice somatic cells frequently express it. It was reported that minor component of the ganglioside fraction derived from primary tumors of 3LL is NGcGM3. Interestingly in metastatic lesions the presence of NGcGM3 reach the 73.4% of total lipid bound sialic acid. Anti idiotypic antibodies (Ab2) are proposed as therapeutic vaccines when they bear the internal image of tumor antigens. Racotumomab is a gamma type anti idiotypic antibody that is able to trigger a strong anti anti idiotypic antibody (Ab3) response. These Ab3 antibodies have the same antigenic specificity than the Ab1 (P3) but they are substantially different from the internal image of it. Additionally, since it was demonstrated that immunization with Racotumomab elicited an anti NGcGM3 antibody response in humans, the question about to what extent the presence of the vaccine target antigen in the tumor decides the effect of the active treatment remains open. In this work, we evaluated the association of NGcGM3 expression in tumor cells in relation to the antitumor activity of the vaccine. Evaluation of Racotumomab antitumor activity over 3LL primary tumor showed no difference in tumor growth rate between treated and control mice. Moreover, the vaccine showed no antitumor activity in the metastatic dissemination in C57BL/6 mice treated with iv 3LL cells. However, when Racotumomab activity was evaluated in a spontaneous metastasis model it was observed a reduction in lung metastatic nodules in treated group compared to the control. The amount of NGcGM3 in 3LL cells can be increased by preincubation in vitro with purified NGc. Using this NGcGM3 positive metastasis model, we observed that Racotumomab was able to develop an active antitumor activity. The number of experimental metastases was reduced significantly between control and treated group (3.5 (1-18) vs 0.5(1-10), control vs Racotumomab. p&amp;lt;0.05, Kruskal-Wallis test). In a preliminary study of the therapeutic combination or Racotumomab with chemotherapy, mice were injected with 3LL cells and treated with Racotumomab, Pemetrexed or both. The combination of the vaccine and Pemetrexed show a similar antitumor effect than Racotumomab alone. Our results suggest a close association between the expression of NGcGM3 and the antitumor activity of Racotumomab. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-108. doi:1538-7445.AM2012-LB-108

New Antigens in Non-small Cell Lung Cancer Detected Both in Serology and Tissue

New Antigens in Non-small Cell Lung Cancer Detected Both in Serology and Tissue

Expression of the sperm fibrous sheath protein CABYR in human cancers and identification of α-enolase as an interacting partner of CABYR-a

Calcium-binding tyrosine phosphorylation regulated protein (CABYR), a family of isoforms resulting from alternative splicing, has been identified as a cancer/testis antigen (CT88) in lung cancer and hypothesized to be a promising target for immunotherapy. Here, we report the expression of CABYR in various cancer tissues/cell lines. Expression profiles of individual isoforms were different among cancers. Furthermore, protein and mRNA levels did not correlate for individual isoforms. While CABYR-c/d were the most abundant splicing variants, CABYR-a was the predominant protein isoform. Finally, CABYR-a, but not CABYR-c, was found to interact with α-enolase in vivo. Collectively, the data indicate that CABYR is a CT antigen widely expressed in diverse cancer cells. However, individual protein isoforms may be differentially regulated by post-transcriptional and post-translational mechanisms and may have a unique role in carcinogenesis. The protein expression pattern of various CABYR isoforms is important with regard to the consideration of using CABYR as a target antigen for the development of vaccines for cancer therapy.

Immunotherapy for Lung Cancers

Lung cancer is the leading cause of cancer-related deaths worldwide. Although treatment methods in surgery, irradiation, and chemotherapy have improved, prognosis remains unsatisfactory and developing new therapeutic strategies is still an urgent demand. Immunotherapy is a novel therapeutic approach wherein activated immune cells can specifically kill tumor cells by recognition of tumor-associated antigens without damage to normal cells. Several lung cancer vaccines have demonstrated prolonged survival time in phase II and phase III trials, and several clinical trials are under investigation. However, many clinical trials involving cancer vaccination with defined tumor antigens work in only a small number of patients. Cancer immunotherapy is not completely effective in eradicating tumor cells because tumor cells escape from host immune scrutiny. Understanding of the mechanism of immune evasion regulated by tumor cells is required for the development of more effective immunotherapeutic approaches against lung cancer. This paper discusses the identification of tumor antigens in lung cancer, tumor immune escape mechanisms, and clinical vaccine trials in lung cancer.

Isolation and characterization of human lung cancer antigens by serological screening with autologous antibodies

Serological analysis of a recombinant cDNA expression library (SEREX) derived from two lung adenocarcinoma cancer cell lines using autologous sera led to the isolation of 41 positive cDNA clones comprising 28 different antigens. They coded for a variety of nuclear and cytoplasmic proteins. Among the antigens, nucleoporin 107 (NUP107) was isolated most frequently (5 of 41 clones). The second most frequently isolated antigen was coded for by C21orf58 (4 of 41 clones). During serological analysis of selected antigens based on their reactivity to sera from normal individuals and lung cancer patients, none of the antigens showed a cancer-restricted recognition pattern. However, five genes including NUP107 showed higher expression when we examined the changes in gene expression in five different adenocarcinoma cell lines, including those used in SEREX, compared with their levels in normal lung tissues by cDNA microarray analysis. On the other hand, the expression levels of five genes including C21orf58 were down regulated in all adenocarcinoma cell lines. This SEREX study combining comprehensive gene expression assays has added to the growing list of lung cancer antigens, which may aid the development of diagnostic and immunotherapeutic reagents for patients with lung cancer.

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.

A study on the specific immunological effect induced by DCs loaded with autospecific lung cancer antigen

Objective To discuss the specific immunological effect induced by DCs loaded with autospecific lung cancer antigen. Methods Primary lung cancer cells were cultured in vitro and prepared to antigen through thaw and freeze. Antigen was presented to tumor infiltrating lymphocyte(TIL) and T lymphocyte derived from peripheral blood by dendritic cells(DCs). The specific anti-tumor immunological effect of DCs vaccine was 25.46 ± 3.02 and 27.52 ± 2.68. The kill rate of CTIL was higher than the CTL( P ＜ 0.05 ). Conclusion The kill rate of CTIL sensitized by DCs loaded autospecific lung cancer antigen is higher than CTL. It provides a new clue for biotherapy of lung cancer. Key words: Lung cancer; Dendritic cell; T lymphocyte; Kill rate

Serum squamous cell carcinoma-related antigen in lung cancer--a marker for the extent of the disease and response to therapy

Serum squamous cell carcinoma-related antigen in lung cancer--a marker for the extent of the disease and response to therapy

Immunohistochemical detection of carcinoembryonic antigen and P-glycoprotein in small cell lung cancer at diagnosis and relapse, with special reference to the tissue expression of CEA and response to chemotherapy

Small cell lung cancer (SCLC) is one of the most sensitive tumors to drug therapy; however, the majority of patients eventually relapse within a few years. Emergence of drug resistance is thought to play a major role in the dismal course of this disease. However, the mechanism of drug resistance in SCLC still remains obscure. Based on the clinical observation that a significant proportion of patients with relapsing tumor show an elevated serum carcinoembryonic antigen (CEA) concentration while serum neuron-specific enolase (NSE) concentration remains normal, we attempted to determine whether the tissue of CEA is indicative of a clonal change in SCLC, in contrast with the tissue expression of NSE and P-glycoprotein (P-gp). We examined 22 SCLC patients with tumor specimens available both at diagnosis and at relapse. Of the 22 patients, two had CEA expression at diagnosis, and a further three patients showed CEA expression at relapse. It is of note that there were two patients whose tumors expressed NSE alone at diagnosis but expressed CEA alone at relapse. Serum CEA concentration was concordant with the tissue expression of CEA; however, serum NSE concentration was not concordant with the tissue expression of NSE. Tumors with CEA expression at relapse were generally resistant to salvage chemotherapy, while there was no close relationship between the tissue expression of P-gp and refractoriness to drugs at relapse. These findings indicate that the tissue expression of CEA in SCLC is a marker of a clonal change during chemotherapy, and such a clonal change would play a role in the emergence of drug resistance in SCLC.

Lung cancer-associated tumor antigens and the present status of immunotherapy against non-small-cell lung cancer

Despite recent advances in surgery, irradiation, and chemotherapy, the prognosis of patients with lung cancer is still poor. Therefore, the development and application of new therapeutic strategies are essential for improving the prognosis of this disease. Significant progress in our understanding of tumor immunology and molecular biology has allowed us to identify the tumor-associated antigens recognized by cytotoxic T lymphocytes. Immune responses and tumor-associated antigens against not only malignant melanoma but also lung cancer have been elucidated at the molecular level. In a theoretical sense, tumor eradication is considered possible through antigen-based immunotherapy against such diseases. However, many clinical trials of cancer vaccination with defined tumor antigens have resulted in objective clinical responses in only a small number of patients. Tumor escape mechanisms from host immune surveillance remain a major obstacle for cancer immunotherapy. A better understanding of the immune escape mechanisms employed by tumor cells is necessary before we can develop a more effective immunotherapeutic approach to lung cancer. We review recent studies regarding the identification of tumor antigens in lung cancer, tumor immune escape mechanisms, and clinical vaccine trials in lung cancer.

9325 Efficacy of a hypofractionated schedule in electron beam radiotherapy for epithelial skin cancer: analysis of 434 cases

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).

Novel spliced form of a lens protein as a novel lung cancer antigen, Lengsin splicing variant 4

A glutamine synthetase I family protein, Lengsin, was previously identified as a novel lens-specific transcript in the vertebrate eye. In this report, we show for the first time that Lengsin is a novel tumor-associated antigen expressed ectopically in lung cancer. Interestingly, a novel spliced form of human Lengsin termed 'splicing variant 4', gaining exon 3 that codes extra 63 amino acids, is the dominant transcript form in lung cancer cells. Lengsin mRNA could be detected in 7 of 12 (58%) lung cancer cell lines and 7 of 7 (100%) surgically resected lung cancer tissues. On the other hand, Lengsin transcripts could not be detected in normal major tissues or in other cancer cell lines, including melanoma, colorectal carcinoma, breast carcinoma and hepatocellular carcinoma. In addition, knockdown of Lengsin mRNA with RNAi caused cell death and a decrease of cell viability, suggesting that Lengsin has some essential role in cell survival. Since the lens is an immune-privileged site, we regard Lengsin as a highly immunogenic cancer antigen. Anti-Lengsin autoantibodies were detectable in sera of lung cancer patients, although these patients did not show any lens-related disturbances. Hence, Lengsin splicing variant 4 might be an immunogenic lung cancer-specific antigen that is suitable as a diagnostic marker and for molecular targeting therapy, including immunotherapy.