Expression of multiple cancer-testis antigen genes in gastrointestinal and breast carcinomas.

Cancer-testis antigens (CTAs) such as MAGE are selectively expressed in various types of human neoplasms but not in normal tissues other than testis. This characteristic feature of CTAs makes them promising antigens for cancer-specific immunotherapy. A critical requirement for this therapy is identification of promising antigens. In this study, we investigated the expression of 6 genes recently identified by serological analysis of antigens by recombinant expression (SEREX) libraries: NY-ESO-1, LAGE-1, SCP-1, SSX-1, SSX-2, and SSX-4, in many surgical samples of gastrointestinal and breast carcinomas using reverse transcription-polymerase chain reaction. We found relatively high expression of SCP-1 (23.5%) and SSX-4 (20.6%) in gastric carcinoma, LAGE-1 (39.1%) and NY-ESO-1 (23.9%) in oesophageal carcinoma, and SCP-1 (34.1%) in breast carcinoma. We also found frequent synchronous expression with MAGE, including LAGE-1 (46.2%) in oesophageal carcinoma, SSX-4 (46.7%) in gastric carcinoma, and SCP-1 (38.3%) in breast carcinoma. Immunohistochemical analysis of the tumour samples expressing both MAGE-4 and NY-ESO-1 genes demonstrated differences in distribution between MAGE-4 and NY-ESO-1 in serial sections. We concluded that NY-ESO-1, LAGE-1, SCP-1 and SSX-4 genes may be promising candidates for cancer-specific immunotherapy in addition to MAGE, and that polyvalent cancer vaccines may be useful in cases of heterogeneous expressions of CTA genes in gastrointestinal and breast carcinomas.

Dendritic cell vaccination with MAGE peptide is a novel therapeutic approach for gastrointestinal carcinomas.

The MAGE gene is selectively expressed in cancer tissues such as melanoma or gastrointestinal carcinomas, whereas no expression is observed in normal tissues except testis. There are several reports of successful induction of HLA class I-restricted antitumor CTLs using MAGE peptides, and some clinical trials with these immunogenic peptides were reported as effective for some patients with malignant melanoma. However, there are no similar studies in gastrointestinal carcinomas, which are important neoplasms. Autologous dendritic cells (DCs) were generated ex vivo and were pulsed with MAGE-3 peptide, depending on the patient's HLA haplotype (HLA-A2 or A24). Patients were immunized with DC pulsed with MAGE-3 peptide every 3 weeks at four times. Twelve patients with advanced gastrointestinal carcinoma (six stomach, three esophagus, and three colon) were treated, and no toxic side effects were observed. Peptide-specific CTL responses after vaccination were observed in four of eight patients. Improvement in performance status was recognized in four patients. Tumor markers decreased in seven patients. In addition, minor tumor regressions evidenced by imaging studies were seen in three patients. These results suggested that DC vaccination with MAGE-3 peptide is a safe and promising approach in the treatment of gastrointestinal carcinomas.

Expression of Fas ligand in gastric carcinoma relates to lymph node metastasis.

Tumors may escape a host's immune response by means of various mechanisms. The Fas (CD95/APO-1)/Fas ligand (FasL) system is one of the major apoptotic pathways. Recently, it has been reported that tumor cells can express FasL, induce apoptosis in tumor infiltrating lymphocytes, and thus can escape host immune surveillance. In gastric carcinoma, tumor progression by way of the lymphatics is often seen, and lymph node metastasis is a critical factor influencing the recurrence of cancer and its prognosis. We, therefore, investigated the relationship between the expression of FasL and the lymphatic spread of gastric carcinoma. FasL-expression was examined by an immunohistochemical method using 100 surgically resected gastric carcinomas and 55 metastatic lymph nodes. Apoptotic cells among tumor infiltrating T lymphocytes were detected by T lymphocyte staining and the terminal deoxynucleotidyl transferase (TdT) mediated dUTP nick end labeling (TUNEL) method in a series of sections of metastatic lymph nodes. FasL-expression was detected in 86% of primary lesions and 71% of metastatic lymph nodes. In cases with high levels of FasL-expression, the observed expression of lymph node metastases was significant (p=0.047). Moreover, FasL-positive cases with both primary lesions and metastatic lymph nodes showed also distant lymph node metastasis beyond the regional lymph nodes (p=0.030). Apoptosis among tumor infiltrating T lymphocytes was more frequently seen in FasL-positive lesions (p=0.057). Furthermore, patients with FasL-negative primary lesions tended to exhibit longer survival times than patients with FasL-positive primary lesions. The results suggest tumor escape through the lymphatic pathway via FasL-expression in gastric carcinomas.

Expression of MAGE-B genes in esophageal squamous cell carcinoma.

The MAGE-B (MAGE-B1, -B2, -B3, and -B4) genes share strong homology with the MAGE-A gene family. MAGE-B1 and -B2 encode common tumor-specific peptide antigens. There is, however, still very little information about the expression of these genes in human gastro-intestinal carcinomas. We investigated the expression of MAGE-B1 and -B2 genes in 29 cell lines and 53 clinical tumor samples of esophageal squamous cell carcinoma by reverse transcription polymerase chain reaction (RT-PCR). MAGE-B1 and -B2 gene transcripts were detected by RT-PCR in 1 (3%) and 6 (21%) cell lines, and in 9 (17%) and 17 (32%) clinical samples, respectively. Among them, 7 / 29 (24%) cell lines and 19 / 53 (36%) clinical samples expressed at least either MAGE-B1 or -B2. A significant correlation was found between negative MAGE-B gene expression and vascular invasion (P = 0.008). In 45 out of 53 esophageal carcinoma RNA samples, the MAGE-A1, -A2, and -A3 genes were detected in 27 (60%), 23 (51%), and 30 (67%) samples, respectively, while the MAGE-B genes were detected in 18 (40%) samples. The frequency of MAGE-B gene expression in esophageal carcinoma was relatively higher than that observed for gastric or colorectal carcinomas (12% and 2%, respectively). Therefore, the MAGE-B genes could be used as targets in specific immunotherapy of esophageal squamous cell carcinomas.

Hemolytic activities of various phospholipids and their relation to the rate of transfer between membranes.

The correlation between hemolytic activities of various phospholipids and their incorporation into membranes was studied. Short chain phosphatidylcholines can be spontaneously transferred between liposome-liposome and between liposome-erythrocyte membrane. The order of the rate of transfer is as follows: C10:0PC greater than C12:0PC much greater than C14:0PC. These findings indicate that the transfer process may be favored by the short fatty acyl chain of phosphatidylcholines. The transfer of C12:0PC was observed in the direction from egg yolk PC liposome to egg yolk PC liposome, from C12:0PC liposome to erythrocyte membrane, from erythrocyte membrane to egg yolk PC liposome, and from erythrocyte membrane to erythrocyte membrane, but not in the direction from egg yolk PC liposome to erythrocyte membrane or from erythrocyte membrane to C16:0PC liposome. The accumulation of a certain amount of C8:0PC, C10:0PC, or C12:0PC on the erythrocyte membrane caused hemolysis. The order of rate of hemolysis is C8:0PC greater than C10:0PC greater than C12:0PC. C8:0PC induced rapid hemolysis only when the concentration was relatively high; 100-200 microM C8:0PC and 5-10 microM C10:0PC, C11:0PC, or C12:0PC were required for 50% hemolysis. The distribution coefficient of C8:0PC between membranes and buffer may be small as compared to those of C10:0PC and C12:0PC. The hemolytic activity of PC may depend both on the rate of transfer and on the distribution coefficient of the molecule between membrane and buffer. Hemolytic activity of dilauroylphospholipids was also affected by head group modification. The order of hemolytic activity is as follows; dilauroylglycerophospho-choline, -serine greater than -dimethylethanolamine much greater than -ethanolamine. The weak hemolytic activity of dilauroylglycerophospho-dimethylethanolamine and -ethanolamine may be due to poor transfer of these lipids to erythrocytes.

Mechanism of human erythrocyte hemolysis induced by short-chain phosphatidylcholines and lysophosphatidylcholine.

The incorporation and accumulation of a certain amount of short-chain phosphatidylcholine or lysophosphatidylcholine into lipid bilayers of erythrocyte membranes is the first step causing membrane perturbation in the process of hemolysis. Accumulation of dilauroylglycerophosphocholine into membranes makes human erythrocytes "permeable cells"; Ions such as Na+ or K+ can permeate through the membrane, though large molecules such as hemoglobin can not. The "pore" formation was partially reproduced in liposomes prepared from lipids extracted from human erythrocyte membranes; C12:0PC induced the release of glucose from liposomes but did not significantly induce the release of dextran. It was suggested that the phase boundary between dilauroylglycerophosphocholine and the host membrane bilayer or dilauroylglycerophosphocholine rich domain itself behaves as "pores." Erythrocytes could expand to 1.5 times the original cell volume without any appreciable hemolysis when incubated with C12:0PC at 37 degrees C. The capacity of the erythrocytes to expand was temperature dependent. The capacity may play an important role in the resistance of the cells against lysis. The "permeable cell" stage could be hardly observed when erythrocytes were treated with didecanoylglycerophosphocholine and lysophosphatidylcholine. Perturbation induced by accumulation of didecanoylglycerophosphocholine or lysophosphatidylcholine may cause non specific destruction of membranes rather than formation of a kind of "pore."