Cellular and humoral immune responses to a human pancreatic cancer antigen, coactosin-like protein, originally defined by the SEREX method

Among a number of human tumor antigens identified using the serological analysis of recombinant cDNA expression libraries (SEREX), only MAGE-1, tyrosinase, and NY-ESO-1 have been reported to be immunogenic tumor antigens that have the potential to elicit both humoral and cellular immunity. In this study, we determined whether our SEREX-defined pancreatic cancer antigens could be recognized by CTL, and report that one SEREX-defined antigen, coactosin-like protein (CLP), encoded cellular epitopes recognized by HLA-A2-restricted and tumor-reactive CTL. Three CLP peptides at positions 15-24, 57-65, and 10-113 possessed the ability to induce HLA-A2-restricted and tumor-reactive CTL from the PBMC of cancer patients. Subsequently, humoral responses to these peptides were investigated. IgG antibodies specific to the CLP 15-24, 57-65, and 104-113 peptides were detected in sera from 12, 0, and 12 of 12 cancer patients tested, and were also found in 5, 0, and 0 of 9 healthy donors, respectively. IgE antibodies specific to these peptides were also detected in sera from certain cancer patients and healthy donors. Since peptide-specific IgE was detected, type-I allergy to these peptides was tested. Unexpectedly the CLP 57-65 peptide, to which IgE was found in only 2 healthy donors, but not the other two peptides, was found to elicit an immediate-type hypersensitivity in all 10 healthy volunteers tested. These results indicate that identical antigenic peptides can be recognized by both cellular and humoral immune systems to a tumor-associated antigen. The CLP 15-24 and 104-113 peptides might be appropriate vaccine candidates for peptide-based immunotherapy of HLA-A2(+) cancer patients.

Effective targeted cytotoxicity of neuroblastoma cells

BACKGROUND/PURPOSE

Despite aggressive treatment with surgery, chemotherapy, and radiotherapy, the prognosis for many children with neuroblastoma remains poor. Targeted toxins represent novel cancer therapeutics designed to selectively target and kill cancer cells. The authors have developed a novel fusion toxin, DT5F11, consisting of truncated diphtheria toxin (DT(A)) linked to a single chain antibody (sc5F11) targeting the GD(2) antigen found on most neuroblastoma cells. This report describes the construction, expression, and in vitro function of DT5F11.

METHODS

Utilizing restriction enzyme digestion, polymerase chain reaction amplification, and gel electrophoresis, the prkDTL5F11 plasmid was created by the fusion of distinct coding sequences for a single-chain GD(2) targeting antibody (sc5F11) and truncated diphtheria toxin (DT(A)). DH5alpha Escherichi coli-competent cells were transformed with prkDTL5F11; DNA was amplified, isolated, and sequenced. The fusion protein was expressed and assayed by Western blot. Targeted cytotoxicity was analyzed on GD(2)-positive (SK-N-AS, IMR-32, SK-N-MC, LAN-1) and GD(2)-negative (HeLa) cells.

RESULTS

Fluorescent dye-labeled cycle sequencing identified the constructed fusion toxin gene. Western blot analysis using a mouse antihuman DT(A) antibody showed a 69-kD band identifying the fusion toxin, DT5F11. Targeted cell killing with DT5F11 was seen only in GD(2) positive cells.

CONCLUSIONS

This study demonstrates creation of a novel fusion toxin with effective GD(2)-targeted cellular toxicity. Further investigation of this fusion toxin as a therapeutic agent in the management of neuroblastoma is warranted.

[MG7 expression in helicobacter pylori-related gastric diseases]

OBJECTIVE

To determine the influence of Helicobacter pylori (H. pylori) on gastric cancer-related antigen MG7 expression.

METHODS

The H. pylori infection and the expression level of antigen MG7 in gastric mucosa were determined by HE stain, PCR, ELISA and immunohistochemistry in 291 patients with H. pylori-related conditions, among whom 34 were followed-up.

RESULTS

No significant difference was found between H. pylori-negative and H. pylori-positive intestinal metaplasia, atrophic gastritis and dysplasia of gastric epithelium in positive rate of antigen MG7 expression. There was significant difference between H. pylori-negative and H. pylori-positive superficial gastritis in the positive rate of MG7 expression (P < 0.05). During follow-up, one of 3 H. pylori-negative cases turned to be H. pylori-positive, and its MG7 expression turned to be higher at the same time. Three of 31 H. pylori-positive patients were discovered as having early gastric cancer, among whom one with antigen MG7 expression (+ + +) was found to have a reduced Mg7 expression accompanied with H. pylori eliminutied after operation.

CONCLUSION

There is correlationship between H. pylori infection and MG7 expression in superficial gastritis. Although the MG7-positive lesions with H. pylori infection shows a benign nature in morphology, they also have the potential risk of developing into gastric cancer. Therefore, they should be followed up, during which special attention should be paid to patients with increased MG7 expression.

PAGE4 is a cytoplasmic protein that is expressed in normal prostate and in prostate cancers

PAGE4 is an X chromosome-linked cancer-testis antigen that was identified by expressed sequence tags database mining and a functional genomic approach. PAGE4 is preferentially expressed in normal male and female reproductive tissues and also in a variety of cancers including prostate. In the present study, we have used in situ hybridization to show that PAGE4 mRNA is expressed only in the epithelial cells of normal and prostate-cancer specimens. Analysis of the protein product encoded by the PAGE4 mRNA reveals that it encodes a Mr 16,000 protein and is detected in tissue extracts from both normal prostate and prostate cancer. Cell fractionation analysis of PAGE4 protein indicates that PAGE4 is localized in the cytoplasm of the cell. Furthermore, cDNA microarray analysis indicates that the expression of lipoprotein lipase, a gene frequently deleted in prostate cancer, is down-regulated in a cell line that expresses PAGE4.

Identification of BING-4 cancer antigen translated from an alternative open reading frame of a gene in the extended MHC class II region using lymphocytes from a patient with a durable complete regression following immunotherapy

Multiple human cancer Ags have been identified, although little is known concerning which would be most effectively used in cancer immunotherapy. To gain insight into the selection of appropriate Ags, the immunologic reactivity of a patient who had a durable complete regression of melanoma metastases was measured. PBMCs were directly cloned using the monoclonal anti-CD3 Ab OKT3 and IL-2 without any bias introduced by previous culture. A lymphocyte clone recognized a previously unknown shared melanoma Ag that was identified as the BING-4 protein encoded in a gene-rich region of the extended class II MHC. The HLA-A2-restricted BING-4 immunodominant peptide was translated from a 10-aa-long alternative open reading frame. In vitro sensitization against this peptide generated lymphocytes reactive against HLA-A2(+) melanomas. Real-time semiquantitative RT-PCR analysis revealed that 8 of 15 melanoma cell lines overexpressed BING-4, and this correlated with recognition by lymphocytes. Overexpression was not found in normal tissues or other tumor types. Thus, BING-4 represents another candidate Ag for possible use in the immunotherapy of patients with melanoma.

Oncofetal antigen 5T4 expression as a prognostic factor in patients with gastric cancer

BACKGROUND

Oncofetal antigen 5T4 is defined by a monoclonal antibody raised against placental trophoblast membranes. Antigen 5T4 is reported to be expressed only on trophoblasts and neoplastic cells and would be a potentially useful marker for neoplastic cells.

MATERIALS AND METHODS

We evaluated the expression of 5T4 oncofetal antigen in gastric cancer by immunohistochemistry and investigated whether or not the expression of this antigen is correlated with the prognosis of patients with gastric cancer.

RESULTS

The 5T4 antigen was detected in 51.6% of primary gastric cancer (n = 62) and 5T4-reactivity was more frequently observed in carcinoma with lymph node metastasis (p < 0.05). The overall survival of 5T4-positive patients was significantly worse than that of 5T4-negative patients, analyzed by the log-rank test (p < 0.05), although multivariate analysis indicated that 5T4 expression was not an independent prognostic factor.

CONCLUSION

The assessment of 5T4 expression may be useful in identifying gastric cancer patients with a poor prognosis.

Expression of cancer/testis antigens in cutaneous T cell lymphomas

Cancer/testis-antigens (CTA), a novel and expanding family of immunogenic proteins detected by serological screening of recombinant cDNA expression libraries, encompass promising candidate targets for T-cell based immunotherapy. We screened kryo-preserved tissue of cutaneous T cell lymphoma (CTCL, n=36) such as mycosis fungoides (MF, n=17), pleomorphic cutaneous T-cell lymphoma (n=8) and Sezary's syndrome (SS, n= 11) as well as a non-malignant entity (small plaques parapsoriasis, SPP, n=5), for the expression of CTA by RT-PCR and Northern blot hybridization. From a panel of eleven CTA (MAGE-1, MAGE-C1, MAGE-3, BAGE, GAGE, SSX-1, SSX-2, SSX4, SCP-1, NY-ESO-1 and TS85) (HOM-Tes-85), mRNA expression could be detected for SCP-1 in 8/17 MF and 6/8 pleomorphic CTCL patients but was completely absent in small plaques parapsoriasis. SS patients had a more heterogeneous antigen expression pattern: Gage (1/11), MAGE-1 (3/11), MAGE-3 (6/11), MAGE-C1 (5/11), NY-ESO-1 (7/11) and TS85 (5/11), with expression of MAGE-3 confirmed by immunohistochemistry. CTA could provide defined targets for antigen-based vaccination in a high percentage of cases with CTCL. SCP-1 might serve as an additional diagnostic indicator in early and clinically indistinct lesions suspicious for cutaneous T-cell lymphoma.

[Efficient expression of exogenous human gp96 gene in tumor cells]

BACKGROUND & OBJECTIVE

Immunization of mice with preparations of heat shock protein(HSP) gp96 isolated from cancer cells has been shown to elicit specific protective cytotoxic T lymphocyte response against cells from which gp96 originate. This phenomenon exploits a new practicable pathway for cancer immunotherapy. But gp96 is generally expressed at low level in cells. Gp96 preparations from limited cells or tissue are difficult to meet the needs of study. So the current study aims to acquire minoclonal cell lines expressing gp96 at high level in order to prepare enough gp96 with high quality.

METHODS

The recombinant plasmid pcDNA-hgp96 of human gp96 cDNA was constructed by ligating the fragment of gp96 cDNA into the pcDNA3 plasmid, a eucaryotic expressing vector. Then the recombinant plasmid was transfected into Hela cells and the stable transfectants were selected with G418. The expression level of gp96 of the positive monoclonal cells was detected by Western blot analysis.

RESULTS

The recombinant expression plasmid of human gp96 cDNA was successfully constructed. The monoclonal cell lines with stable transfection were obtained. A monoclonal cell line expressing gp96 on high level was selected out.

CONCLUSIONS

The monoclonal cell line expressing gp96 at high level has been successfully established, which lays the groundwork for the study of its antitumor immunity.

Serological cloning of PARIS-1: a new TBC domain-containing, immunogenic tumor antigen from a prostate cancer cell line

Identifying immunogenic tumor antigens plays a critical role in developing efficient diagnostic and therapeutic strategies for treatment of cancer. Using a recently developed technology, serological identification of antigens by recombinant expression cloning (SEREX), we identified a total of 8 genes whose expression elicited antibody responses in prostate cancer patients. Of the 8 genes, 5 represented known genes in the GenBank database, 2 were previously uncharacterized genes, and 1 showed sequence homology to a mouse gene. The sequence feature and the expression of one of the novel genes, prostate antigen recognized and identified by SEREX (PARIS-1), are determined in this study. The PARIS-1 cDNA is 3257 bp in length and contains a complete open reading frame of 2751 bp encoding for a primary translation product of 917 amino acids. Using Northern blot hybridization assay, we detected a single species of approximately 3.3 kb PARIS-1 mRNA that is differentially expressed in prostate normal and cancer cells. Western blot analysis confirmed the expression of the PARIS-1 protein in these cells. Structure analysis revealed that PARIS-1 protein contains a TBC domain that is conserved in the family of cell cycle-regulatory and Rab GTPase-activating proteins (Rab-GAP). Thus, the PARIS-1 protein may play a role in regulation of cell differentiation and growth or represent a new member of the Rab-GAP family.

Anti-CD20 antibody (IDEC-C2B8, rituximab) enhances efficacy of cytotoxic drugs on neoplastic lymphocytes in vitro: role of cytokines, complement, and caspases

BACKGROUND AND OBJECTIVES

Monoclonal antibody IDEC-C2B8 (rituximab) has been shown to be highly effective in the treatment of non-Hodgkin's lymphomas (NHL). The present study was designed to investigate relationships between the efficacy of IDEC-C2B8 and expression of CD20, presence of complement, and effects of differently acting chemotherapeutic agents used in lymphoma treatment (doxorubicin, mitoxantrone, cladribine, bendamustine).

DESIGN AND METHODS

DOHH-2, WSU-NHL and Raji lymphoma cell lines and ex vivo cells from patients with chronic lymphocytic leukemia (CLL) (n=17) and leukemic B-cell lymphomas (n=9) were studied. Additionally, the effect of interleukin (IL)-2, IL-4, IL-6, IL-13, granulocyte/macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor (TNF)alpha on expression of CD20 molecules per cell was determined.

RESULTS

We demonstrate that 10 mg/mL rituximab saturated 80-95% of CD20 molecules per cell in all tested lymphoma samples. Although rituximab induced only a minor increase of apoptosis, combinations of rituximab with different cytotoxic drugs significantly decreased the IC(30)- and IC(50) dosages of the chemotherapeutic agents necessary for induction of apoptosis irrespective of addition of complement, demonstrating a chemosensitizing effect of rituximab in combination with cytotoxic drugs in the neoplastic lymphocytes. This effect seemed to be independent of the percentage of saturated CD20 molecules. After addition of caspase inhibitors to the cell lines incubated with rituximab and cytotoxic agents, caspase-7 and -8 were found, by Western blotting, to be the executioner caspases, possibly explaining the rituximab-sensitized apoptosis. Preincubation of lymphoma cells with cytokines did not alter the expression of CD20; IL-2 and IL-4 even decreased the rate of apoptosis.

INTERPRETATION AND CONCLUSIONS

We conclude that rituximab sensitizes lymphoma cells to the effect of differently acting cytotoxic drugs used in lymphoma treatment, that this effect does not require complement, and that caspase-7 and -8 may represent the main executioner caspases in chemosensitization by rituximab.

Immunohistochemical study of human pterygium

The purpose of this study has been to evaluate the immunohistochemical characteristics of human pterygial tissues in order to ascertain the possible contribution of an immunological mechanism in the pathogenesis of pterygium and to investigate the presence in the pterygial tissues of some melanoma-associated antigens, in order to evaluate if there may be a small possibility of correlation of the two diseases. Human biopsy specimens of pterygium were obtained by surgery for pterygium excision. Tissue segments were fixed and processed for paraffin embedding. Microtome sections were treated for the immunohistochemical demonstration of IgA, IgM, IgG, CD3, CD20, CD68, HLA-DR, Protein S100, HMB45, and Melan A using the avidin-biotin peroxidase method or the streptavidin biotin-alkaline phosphatase method. The findings suggest that all the effector components of the mucosal immune system are present in the human pterygium and, among the most sensitive markers for melanoma, only S100 shows immunoreactivity. An immunopathogenetic mechanism seems to be responsible for the pathogenesis of pterygium, perhaps being caused by pre-existing conjunctivitis or microtrauma in combination with the patient's predisposition. No correlation between pterygium and melanoma was found.

Enhancement of the complement activating capacity of 17-1A mAb to overcome the effect of membrane-bound complement regulatory proteins on colorectal carcinoma

Adjuvant immunotherapy with 17-1A mAb directed against colorectal carcinoma is found to be effective in patients. However, 52 % of the patients treated with mAb 17-1A showed recurrence within 7 years. This high recurrence rate might be due to inhibition of complement activation by membrane-bound complement regulatory proteins (mCRP). The effect of these complement regulatory proteins might be reduced by blocking mCRP, or be overcome by activating more complement at the tumor cell membrane. In this study the complement-activating capacity of the 17-1A mAb was enlarged by conjugating it to cobra venom factor (CVF) or C3b. The most important C3 regulatory protein, CD55, was blocked using a bispecific mAb directed against the 17-1A / Ep-CAM antigen and CD55. Up to a 13-fold increase in C3 deposition was observed due to 17-1A-CVF and 17-1A-C3b, as compared to 17-1A. CD55 was shown to partly inhibit complement activation by these conjugates. The effect of the bispecific anti-17-1A / Ep-CAM*anti-CD55 mAb was compared with 17-1A conjugates with CVF or C3, and bispecific mAb were shown to be equally or more efficient in complement activation than the 17-1A-CVF or 17-1A-C3b conjugates. Therefore, 17-1A conjugates and anti-17-1A / EpCAM*anti-CD55 bispecific mAb may be promising immunotherapeutic agents for patients with colorectal cancer.

Heterogeneous expression of MAGE-A genes in occult disseminated tumor cells: a novel multimarker reverse transcription-polymerase chain reaction for diagnosis of micrometastatic disease

Systemically disseminated tumor cells have become the subject of intensive research as the presumed seminal precursors of later distant metastasis. We describe here a novel sensitive multimarker nested reverse transcription (RT)-PCR capable of detecting the individual expression of human MAGE-A genes MAGE-1, -2, -3/6, -4, and -12 by rare, disseminated tumor cells in bone marrow and blood of patients with many different types of cancer. We analyzed bone marrow aspirates from 106 patients with breast, lung, colorectal, and prostate cancer and with different sarcomas. Heterogeneous expression of the different MAGE genes was found frequently in all those kinds of malignancies, in sharp contrast to 30 bone marrow and 20 blood samples from healthy donors, which were completely MAGE negative. Expression of at least one MAGE gene in bone marrow was more frequent than cytokeratin-positive tumor cells detected by immunocytochemistry, although the results of both tests overlapped considerably. In 30 patients with clinically localized prostate cancer, analysis by the multimarker MAGE RT-PCR of bilateral bone marrow aspirates from the right and left iliac crest revealed a positivity rate of 60%, which was twice as high as that obtained with either an established prostate-specific antigen RT-PCR or by cytokeratin-based immunocytochemistry. Analysis of primary prostate cancer revealed MAGE expression patterns considerably concordant with those found in the corresponding bone marrow aspirates. Prostate cancer patients carrying an exceptionally high risk of metastatic relapse, as defined by clinical prognostic factors, were significantly more often MAGE positive than patients with a distinctly lower risk (P = 0.02, Fisher's exact test). More frequent MAGE expression in the peripheral blood of patients with metastatic prostate cancer compared with those with clinically localized disease added further evidence for the prognostic impact of the multimarker MAGE RT-PCR. Moreover, MAGE-positive bone marrow samples from a small group of seven sarcoma patients demonstrated the relevance of our multimarker RT-PCR in nonepithelial tumors. Because MAGE antigens can induce autologous cytolytic T lymphocytes in vivo, the determination of individual MAGE expression patterns in cancer patients may furthermore identify candidate vaccine targets for adjuvant immunotherapy.

Depletion of CD25(+) CD4(+) T cells and treatment with tyrosinase-related protein 2-transduced dendritic cells enhance the interferon alpha-induced, CD8(+) T-cell-dependent immune defense of B16 melanoma

Transduction of B16 melanoma cells with IFN alpha (B16-IFN alpha) enhances CD8(+) T-cell-dependent tumor immunity in mice, resulting in delayed outgrowth in vivo. Here we provide evidence that CD4(+) T cells down-regulate the IFN alpha-induced tumor immune defense. Importantly, depletion of regulatory CD25(+) CD4(+) T cells prevented growth of B16-IFN alpha in most mice and promoted long-lasting protective tumor immunity. Rejection of B16-IFN alpha could also be achieved with therapeutic injections of dendritic cells genetically engineered to express the melanoma antigen tyrosinase-related protein 2. These results support the development of novel strategies for the immunotherapy of melanoma using IFN alpha in combination with elimination of regulatory T cells or antigen-specific immunization.

Detection of occult metastatic breast cancer cells in blood by a multimolecular marker assay: correlation with clinical stage of disease

Currently, molecular markers offer the unique opportunity to identify occult metastasis in early stage cancer patients not otherwise detected with conventional staging techniques. To date, well-characterized molecular tumor markers to detect occult breast cancer cells in blood are limited. Because breast tumors are heterogeneous in tumor marker expression, we developed a "multimarker" reverse transcription-PCR assay combined with the highly sensitive electrochemiluminescence automated detection system. Breast cancer cell lines (n = 7), primary breast tumors (n = 25), and blood from normal donors (n = 40) and breast cancer patients [n = 65; American Joint Committee on Cancer (AJCC) stages I-IV] were assessed for four mRNA tumor markers: beta-human chorionic gonadotropin (beta-hCG), oncogene receptor (c-Met), beta 1-->4-N-acetylgalactosaminyl-transferase, and a tumor-associated antigen (MAGE-A3). None of the tumor markers were expressed in any normal donor bloods. Breast cancer cell lines and primary breast tumors expressed beta-hCG, c-Met, beta 1-->4-N-acetylgalactosaminyl-transferase, and MAGE-A3 mRNA. Of the 65 breast cancer patient blood samples assessed, 2, 3, 15, 49, and 31% expressed 4, 3, 2, 1, and 0 of the mRNA tumor markers, respectively. At least two markers were expressed in 20% of the blood specimens. The addition of a combination of markers enhanced detection of systemic metastasis by 32%. In patient blood samples, the MAGE-A3 marker correlated significantly with tumor size (P = 0.0004) and AJCC stage (P = 0.007). The combination of beta-hCG and MAGE-A3 mRNA markers correlated significantly with tumor size (P = 0.04), and the marker combination c-Met and MAGE-A3 showed a significant correlation with tumor size (P = 0.005) as well as AJCC stage (P = 0.018). A multimarker reverse transcription-PCR assay that correlates with known clinicopathological prognostic parameters may have potential clinical utility by monitoring tumor progression with a blood test.

Molecular cloning and expression analysis of feline melanoma antigen (MAGE) obtained from a lymphoma cell line

Melanoma antigens (MAGE) are regarded as inducing tumor-specific immune response and thought to be potential therapeutical agents for cancer immunotherapy. We hereby report the cloning of feline MAGE cDNA obtained from a lymphoma cell line derived from cat malignant lymphoma, and its expression pattern in tumor and normal tissues. The cDNA encoding the MAGE is 1668 base pairs (bp) in length, and contains an open reading frame (ORF) of 936 bp encoding a protein of 311 amino acids. The predicted amino acid sequence has 29-46% of homology with other MAGE proteins from human and mouse. mRNA transcripts for the feline MAGE were detected in certain tumors, but not in adult cat normal tissues except in testis, by reverse transcription polymerase chain reaction (RT-PCR) analysis. This indicates that the expression pattern of feline MAGE mRNA is similar to those of other MAGE family genes in tumors and normal tissues.

Tolerance or immunity to a tumor antigen expressed in somatic cells can be determined by systemic proinflammatory signals at the time of first antigen exposure

Mice transgenic for the E7 tumor Ag of human papillomavirus type 16, driven from a keratin 14 promoter, express E7 in keratinocytes but not dendritic cells. Grafted E7-transgenic skin is not rejected by E7-immunized mice that reject E7-transduced transplantable tumors. Rejection of recently transplanted E7-transgenic skin grafts, but not of control nontransgenic grafts or of established E7-transgenic grafts, is induced by systemic administration of live or killed Listeria monocytogenes or of endotoxin. Graft recipients that reject an E7 graft reject a subsequent E7 graft more rapidly and without further L. monocytogenes exposure, whereas recipients of an E7 graft given without L. monocytogenes do not reject a second graft, even if given with L. monocytogenes. Thus, cross-presentation of E7 from keratinocytes to the adaptive immune system occurs with or without a proinflammatory stimulus, but proinflammatory stimuli at the time of first cross-presentation of Ag can determine the nature of the immune response to the Ag. Furthermore, immune effector mechanisms responsible for rejection of epithelium expressing a tumor Ag in keratinocytes are different from those that reject an E7-expressing transplantable tumor. These observations have implications for immunotherapy for epithelial cancers.

Mining the melanosome for tumor vaccine targets: P.polypeptide is a novel tumor-associated antigen

To identify novel, tumor-specific target antigens for vaccine development, we studied immune responses to P.polypeptide, an M(r) 110,000 integral melanosomal membrane protein associated with the Prader-Willi syndrome. Together with expressed sequence tag (EST) and serial analyses of gene expression (SAGE) library analyses, reverse transcription-PCR and Northern blotting verified that P.polypeptide expression was limited to melanoma and melanocytes. A single dominant epitope corresponding to positions 427-435 (IMLCLIAAV) was identified using allele-specific epitope forecasting combined with work in HLA-A*0201/K(b) transgenic mice. This epitope was then used to generate de novo human P.polypeptide-specific CD8+ T cells capable of recognizing P.polypeptide expressing human tumor cell lines in an HLA-A*0201-restricted fashion. Thus, P.polypeptide may be valuable in the creation of novel therapeutic anticancer vaccines.

Activation of melanoma antigen tumor antigens occurs early in lung carcinogenesis

The melanoma antigen (MAGE)-encoding genes are expressed in various tumor types, including lung, and are thought to be silent in all normal tissues except testis. In search of biomarkers for early lung cancer detection and cancer risk assessment, we investigated frequencies of expressional activation of MAGE-A1, -A3, and -B2 genes in non-small cell lung cancers (NSCLCs). Expression of these genes was evaluated by reverse transcription-PCR (RT-PCR) in 20 primary NSCLC samples and corresponding normal lung tissues as well as in 20 bronchial brush specimens from former smokers without lung cancer. mRNA in situ hybridization was done to confirm the gene expression pattern at the cellular level. Methylation-specific PCR was performed to evaluate the hypomethylation status of CpG sites in the promoter regions of these genes. Among the 20 primary NSCLC samples analyzed, 14 (70%) expressed MAGE-A1 and 17 (85%) each expressed MAGE-A3 and MAGE-B2. A substantial number of normal lung tissues adjacent to NSCLC also had a detectable level of MAGE expression (65, 75, and 80% for MAGE-A1, -A3, and -B2, respectively). We found that 7 (35%), 10 (50%), and 11 (55%) of the adjacent normal lung tissue samples exhibited promoter hypomethylation at MAGE-A1, -A3, and -B2, respectively, compared with 15 (75%), 16 (80%), and 16 (80%) of the NSCLC samples. Among the 20 bronchial epithelium samples from former smokers, 7 (35%), 10 (50%), and 12 (60%) had also detectable -A1, -A3, and -B2 expression, respectively. Activation of MAGE-A1, -A3, and -B2 genes is common not only in NSCLC but also in bronchial epithelium with severe carcinogen insult. These results suggest that MAGE genes may be activated very early in lung carcinogenesis and may be considered as targets for lung cancer prevention.

Laser scanning cytometry evaluation of MART-1, gp100, and HLA-A2 expression in melanoma metastases

Assessment of antigen expression by solid tumors has relied predominantly on immunohistochemistry, flow cytometry, and more recently quantitative real-time polymerase chain reaction. However, all these techniques present intrinsic limits. The laser scanning cytometer, by combining the properties of light and fluorescence microscopy with those of laser cytometry, can quantitatively and objectively analyze hypocellular samples such as fine-needle aspirates on an individual cell basis. To validate the fidelity of laser scanning cytometry for quantitative immunophenotyping of fine-needle aspirates, the authors measured the expression of the melanoma-associated antigens MART-1 and gp100 as well as HLA-A2, a HLA class 1 restriction element associated with their recognition by melanoma-specific T cells. Expression of melanoma antigens and HLA was measured by laser scanning cytometry and immunohistochemistry in fine-needle aspirates from melanoma metastases. In addition, transcription levels of both melanoma antigens were recorded by quantitative real-time polymerase chain reaction. A quantity of less than 1,000 cells per sample (average 682 cells) was sufficient for the analysis. Laser scanning cytometry estimates correlated with those of immunohistochemistry and quantitative real-time polymerase chain reaction for MART-1 and gp100. A good correlation in HLA-A2 detection by laser scanning cytometry and immunohistochemistry was also observed. Moreover, the laser scanning cytometer could discriminate subsets of cells from the same lesion with heterogeneous melanoma antigen expression, leading to the observation that cells with a DNA index greater than 2.5 expressed significantly less gp100. Thus, laser scanning cytometry yields detailed information on protein expression in individual cells and represents a new tool for dissecting the immune response in the tumor microenvironment.

Expression of 17-1A antigen and complement resistance factors CD55 and CD59 on liver metastasis in colorectal cancer

Despite radical surgery, the prognosis for colorectal cancer patients with liver metastases has not changed markedly. Furthermore, no standard adjuvant therapeutic regimen has been developed. Adjuvant therapy with monoclonal antibodies (e.g., against 17-1A), which has been shown to be effective in preventing metastatic relapse in patients with Dukes' C colorectal cancer, might be a promising approach for these patients. However, the cytotoxic effects of monoclonal antibodies can be blocked by coexpression of complement resistance factors that inhibit antibody-dependent complement-mediated cytotoxicity. We therefore analyzed immunohistochemically the expression of 17-1A and the membrane-bound complement resistance factors CD55 and CD59 on metastatic tumor cells in the livers of 71 patients with colorectal carcinoma who had undergone resection of their metastases with curative intent. In 67 (94%) of 71 patients, liver metastases with homogeneous expression of 17-1A was seen. Heterogeneous expression of 17-1A was seen in four patients (6%). Heterogeneous expression of CD55 or CD59 was observed in 8 (11%) of 71 patients and 4 (6%) of 71 patients, respectively. None of the patients showed homogeneous expression of either CD55 or CD59. All patients with CD55 or CD59 expression showed homogeneous 17-1A expression, whereas none of the four patients with heterogeneous 17-1A expression was positive for CD55 or CD59. Our data indicate that 17-1A is widely expressed on liver metastases of patients with colorectal carcinoma. Therefore patients with completely resected liver metastases might be suitable candidates for adjuvant therapy with and-17-1A antibody since only a few of these lesions showed coexpression of complement resistance factors.

MAGE-A genes are not expressed in human leukemias

Immunotherapy is promising to improve the prognosis of human leukemias, at least as adjuvant treatment. Tumor-associated antigens such as antigens encoded by MAGE-A1, -A2, -A3, -A4, -A6 and -A12 genes might provide tools in this field. We demonstrated recently that the presentation peptides encoded by MAGE-A genes might make leukemic blasts suitable targets to cytolytic T lymphocytes. We reported previously negative data of MAGE-A1 gene expression in hematological malignancies, but in further studies positive results of MAGE-A gene expression were published in some subtypes of hematological malignancies such as T leukemia, myeloma and Hodgkin's disease. This led us to enlarge the screening of MAGE-A gene expression in human leukemias. In the RT-PCR screening of a large panel including 154 patients, only weak signal were detected in a few samples. We conclude that MAGE-A genes are not expressed in human leukemias.

Genomic structure, chromosomal localization and expression profile of a novel melanoma differentiation associated (mda-7) gene with cancer specific growth suppressing and apoptosis inducing properties

Abnormalities in cellular differentiation are frequent occurrences in human cancers. Treatment of human melanoma cells with recombinant fibroblast interferon (IFN-beta) and the protein kinase C activator mezerein (MEZ) results in an irreversible loss in growth potential, suppression of tumorigenic properties and induction of terminal cell differentiation. Subtraction hybridization identified melanoma differentiation associated gene-7 (mda-7), as a gene induced during these physiological changes in human melanoma cells. Ectopic expression of mda-7 by means of a replication defective adenovirus results in growth suppression and induction of apoptosis in a broad spectrum of additional cancers, including melanoma, glioblastoma multiforme, osteosarcoma and carcinomas of the breast, cervix, colon, lung, nasopharynx and prostate. In contrast, no apparent harmful effects occur when mda-7 is expressed in normal epithelial or fibroblast cells. Human clones of mda-7 were isolated and its organization resolved in terms of intron/exon structure and chromosomal localization. Hu-mda-7 encompasses seven exons and six introns and encodes a protein with a predicted size of 23.8 kDa, consisting of 206 amino acids. Hu-mda-7 mRNA is stably expressed in the thymus, spleen and peripheral blood leukocytes. De novo mda-7 mRNA expression is also detected in human melanocytes and expression is inducible in cells of melanocyte/melanoma lineage and in certain normal and cancer cell types following treatment with a combination of IFN-beta plus MEZ. Mda-7 expression is also induced during megakaryocyte differentiation induced in human hematopoietic cells by treatment with TPA (12-O-tetradecanoyl phorbol-13-acetate). In contrast, de novo expression of mda-7 is not detected nor is it inducible by IFN-beta+MEZ in a spectrum of additional normal and cancer cells. No correlation was observed between induction of mda-7 mRNA expression and growth suppression following treatment with IFN-beta+MEZ and induction of endogenous mda-7 mRNA by combination treatment did not result in significant intracellular MDA-7 protein. Radiation hybrid mapping assigned the mda-7 gene to human chromosome 1q, at 1q 32.2 to 1q41, an area containing a cluster of genes associated with the IL-10 family of cytokines. Mda-7 represents a differentiation, growth and apoptosis associated gene with potential utility for the gene-based therapy of diverse human cancers.

MAGE-A gene expression pattern in primary breast cancer

Melanoma antigen (MAGE)-A-derived peptides elicit a strong in vitro T-cell response against tumor cells. For determination of MAGE-A1, -2, -3, -4, -6, and -12 expression profile in invasive breast cancer, we developed a multiplex seminested reverse transcription-PCR-method. In total, 18 of 67 (27%) tumors were positive for at least one of these MAGE transcripts, and the expression pattern was heterogeneous: MAGE-A1 was positive in 4 of 67 (6%), MAGE-A2 in 13 of 67 (19%), MAGE-A3 in 7 of 67 (10%), MAGE-A4 in 9 of 67 (13%), MAGE-A6 in 10 of 67 (15%), and MAGE-A12 in 6 of 67 (9%) patients. The MAGE-A transcripts were more frequently expressed in ductal breast carcinomas compared with other histomorphological types. We observed a preferential expression of MAGE-A in patients at a higher risk of recurrence: those harboring tumors with high levels of the protease urokinase-type plasminogen activator and its inhibitor plasminogen activator inhibitor 1, high score of the Ki-67 proliferation antigen, and lesser degree of differentiation. Our findings suggests a potential involvement of MAGE-A in tumor progression, with potential implications for active immunotherapy.

KAI1/CD82 expression as a prognosic factor in sporadic colorectal cancer

BACKGROUND

Since its identification as a suppressor gene for prostate cancer metastasis, down-regulation of KAI1/CD82 in a variety of malignancies has been reported.

MATERIALS AND METHODS

Using immunohistochemistry, we examined KAI1/CD82 expression in surgical specimens obtained from 70 patients with advanced colorectal cancer and its correlation with clinicopathological factors, to clarify their prognostic significance.

RESULTS

KAI1/CD82 expression was positive in 55% of the 70 colorectal cancers. There were statistically significant correlations between KAI1/CD82 expression and Dukes' stage, venous invasion, lymph node metastasis, tumor differentiation and liver metastasis. The significant correlation between KAI1/CD82 expression and outcome among patients with Dukes' C cancer (p=0.024) is particularly noteworthy. On multivariate analysis, KAI1/CD82 expression and Dukes' stage were identified as significant and independent prognostic factors (p=0.006 and 0.045, respectively).

CONCLUSION

KAI1/CD82 expression closely correlates with clinicopathological factors for colorectal cancers. KAI1/CD82 expression appears to be a useful prognostic marker.