[Effective transcatheter arterial embolization for hepatic metastasis in a case of AFP producing gastric cancer]

We experienced a case of effective transcatheter arterial embolization (TAE) for hepatic metastasis in a AFP producing gastric cancer. A 51-year-old man with 2 type gastric cancer (H0) underwent subtotal gastrectomy (D2). The serum AFP level was 134.3 ng/ml, and AFP positive tumor cells were detected by PAP method. After the operation, the serum AFP level initially decreased but re-increased on the 7th postoperative month, and metastatic lesions of the liver were detected by CT scan. After the patient was treated 4 times by TAE, the serum AFP level returned within normal range and the metastatic tumors of the liver decreased markedly. Therefore liver resection was performed at the 28th month after the first operation. Total necrosis of metastatic liver lesions was confirmed. This patient has been well without recurrence signs for 10 years since operation. It is concluded that TAE should be used to treat hepatic metastasis in the case of an AFP producing gastric cancer.

[A study about the mechanism of hepatocyte injury induced by endotoxin--interaction of Kupffer cells and polymorphonuclear neutrophils (PMNs)]

Focusing our attention on the TNF (tumor necrosis factor) produced by Kupffer cells (KCs). The role of KCs and polymorphonuclear neutrophils (PMNs) in endotoxin (LPS)-induced hepatocellular injury was investigated. This study used the culture fluid supernatant of KCs which had been stimulated with LPS as the "LPS stimulation supernatant", and evaluated hepatocellular injury as ornithine carbamyl transferase percent leakage. There was no difference between groups I (HCs: hepatocytes) and II (HCs + PMNs), but there were differences between groups I and III (HCs + LPS stimulation supernatant, groups II and IV (HCs + LPS stimulation supernatant + PMNs), and III and IV. There was no significant difference between III and V (III + anti-TNF antibody), but a difference was found between IV and VI (IV + anti-TNF antibody). These findings suggest that PMNs activated by KCs-generated TNF as well as KCs-derived humoral factors other than TNF play a role in the development of LPS-induced hepatocellular injury.

[Liver resection in a case of multiple liver metastases of gastric cancer following hepatic arterial infusion chemotherapy]

A 61-year-old-man underwent subtotal gastrectomy (D2) for advanced gastric cancer with multiple liver metastases. After the operation, repeated hepatic arterial infusion chemotherapy was performed employing implantable catheter and port system with CDDP and MMC. The result was that the liver tumors showed a remarkable regression in size, and the serum CA 19-9 level decreased within normal range. But the tumor in the lateral segment grew and the CA 19-9 level increased again. There was no evidence of metastasis or recurrence except in the liver, and the metastatic tumors in right lobe became smaller by hepatic arterial infusion chemotherapy at this time. Therefore, lateral segment resection was performed for reductive surgery 14 months after the first operation. After that, the liver tumors did not grow and CA 19-9 kept within the normal range, while hepatic arterial infusion chemotherapy could be given. Thus, it seems that liver resection for reduction surgery following hepatic arterial infusion chemotherapy should be considered as a treatment for multiple liver metastases.

Expression of a CD44 variant containing exons 8 to 10 is a useful independent factor for the prediction of prognosis in colorectal cancer patients

PURPOSE

To determine the expression of the CD44 variant containing a variant exon 8 to 10 product (CD44v8-10) in colorectal cancer and to evaluate its prognostic value.

MATERIALS AND METHODS

CD44v8-10 was studied in resected tumors and normal mucosae obtained from 215 colorectal cancer patients (118 colon cancer and 97 rectal cancer). The expression of CD44v8-10 was analyzed immunohistochemically using the anti-CD44v8-10 monoclonal antibody (mAb) 44-1V.

RESULTS

One hundred of 215 cancer tissues expressed CD44v8-10. Positive staining was intense mainly on the cell membranes. There was no significant correlation between expression of CD44v8-10 and histologic type, primary tumor, lymphatic invasion, venous invasion, or peritoneal invasion. There were significant correlations between CD44v8-10 immunoreactivity and both lymph node and hematogenous metastasis. Patients with CD44v8-10-positive tumors had a greater relative risk of death compared with those whose tumors were CD44v8-10-negative. Among 169 patients who underwent curative resection, CD44v8-10 expression correlated with a high recurrence rate. The 5- and 10-year survival rates were 90.3% of patients with CD44v8-10-negative tumors, and 72.1% and 58.0% of those with CD44v8-10-positive tumors, respectively; these differences between the two groups of patients were significant (P < .01). In multivariate analysis using the Cox regression model, CD44v8-10 expression emerged as an independent prognostic indicator.

CONCLUSION

The results suggest that CD44v8-10 plays a role in metastasis of colorectal cancer, and tha CD44v8-10 expression may be a biologic marker of prognostic significance.

Expression of CD44 variant exons 8-10 in gastric cancer

The expression of CD44 variant containing variant exons 8-10 product (CD44v8-10) was studied by western blot analysis and immunohistochemistry in gastric cancers using a monoclonal antibody, 44-1V. On western blots, a single band of 130 kD was recognized in stomach cancer cell lines. CD44v8-10 expression, with reactivity localized in the cell membrane, was found in 65 (33.5%) of the 194 advanced gastric cancers. There was no correlation between CD44v8-10 immunoreactivity and serosal, lymphatic, or lymph node invasion. However, there was significant correlation with CD44v8-10 immunoreactivity and venous invasion. CD44v8-10-positive cancers were more frequently associated with hematogenous metastasis than those which were immunonegative. There was an inverse association between CD44v8-10 immunoreactivity and peritoneal dissemination, especially in diffuse type adenocarcinomas. These observations indicate that CD44v8-10 may play a role in the metastasis of gastric cancer.

Predicting the viability of grafted livers in rats through a rapid and sensitive metabolic indicator assessed by 31P-NMR spectroscopy

The present study was undertaken to clarify whether a correlation exists between the hepatic ratio of the beta-phosphorus moiety of ATP (beta-ATP) to inorganic phosphate (Pi), measured by 31P nuclear magnetic resonance spectroscopy 1 h after the reestablishment of portal blood flow, and the survival rate of rats following liver transplantation. This ratio was compared with the arterial ketone body ratio [AKBR (acetoacetate/3-hydroxybutyrate)], which is accepted as a reliable indicator of liver viability. After the transplantation of fresh livers, the 1-week survival rate was 92% and the beta-ATP/Pi ratio was 64% of the normal level. When the liver grafts were subjected to warm ischemia for 25 min or 45 min prior to harvesting, the 1-week survival rate decreased to 43% and 0%, respectively, and the beta-ATP/Pi ratio dropped to 31% and 18% of the normal level, respectively. On the other hand, the AKBR was about 25% of the normal level after transplantation of fresh livers, while it was 37% and 48% after transplantation with 25 min and 45 min of warm ischemia, respectively. However, 4 h after the reestablishment of portal blood flow, the AKBR correlated with the beta-ATP/Pi ratio in both the fresh graft group and the 45-min warm ischemic damage group. These results show that the beta-ATP/Pi ratio provides an accurate evaluation of a graft viability even at an extremely early stage following liver transplantation, and should prove useful for the early diagnosis of primary graft nonfunction after liver transplantation.

[The role of CD44 adhesion molecules]

CD44 is a transmembrane glycoprotein involved in the interaction between cells and extracellular matrix. CD44 is ubiquitously expressed on cells, and has been thought to be a cell adhesion molecule with proposed functions in extracellular matrix binding, cell migration and lymphocyte homing. In 1991, Stamenkovic et al. showed the existence of two forms of CD44: a hematopoietic (standard) and an epithelial form which was highly expressed by carcinomas. The alternative splicing of 10 variant exons encoding the membrane proximal portion of the external domain of CD44, in particular, results in many variant isoforms. These may play a critical role in malignant behavior and in determining organ specificity in metastasis.

Possible involvement of protein-tyrosine kinases such as p72syk in the disc-sphere change response of porcine platelets

We previously reported that p72syk, a non-receptor tyrosine kinase, was activated maximally at 10 s after thrombin or thromboxane A2 stimulation, even in platelets that were not allowed to aggregate [Taniguchi et al. (1993) J. Biol. Chem. 268, 2277-2279; Maeda et al. (1993) Biochem. Biophys. Res. Commun. 197, 62-67]. Then, the change in the shape of porcine platelets induced by the thromboxane A2 analogue, STA2, and the role of protein-tyrosine kinases including p72syk in this response were evaluated, using the shape-change parameter. We show that p72syk activation is correlated with the disc-sphere change in a time- and dose-dependent manner following stimulation by STA2. Tyrphostin B44, a potent protein-tyrosine kinase inhibitor, reduced the thromboxane A2-evoked p72syk activation and the disc-sphere change in a dose-dependent manner. Furthermore, the translocation of p72syk to the cytoskeleton-rich fraction and an increase in the tyrosine phosphorylation of an about 120 kDa protein were observed during the disc-sphere change induced by STA2. These lines of evidence suggest that the activation of protein-tyrosine kinases such as p72syk may be involved in the disc-sphere change response in thromboxane A2-stimulated porcine platelets.

[A case of duodenal duplication and a review of reported cases]

We report a case of duodenal duplication and review of literatures on 43 cases reported in Japan including ours. A 34-year-old female who was admitted with chief complaints of epigastric pain and hematoemesis. An endoscopic examination and a hypotonic duodenography revealed a protruding tumor with bleeding ulcer. Wedge resection of the duodenum, including the lesion, was performed. A diagnosis of duodenal duplication was made by histopathological examination.

[Quality of life in patients with advanced gastric cancer receiving AO-90, a methionine-free intravenous amino acid solution, with 5-fluorouracil and mitomycin C]

We conducted a randomized, multicenter, controlled trial of AO-90, a methionine-free 7.43% intravenous amino acid solution, in patients with advanced recurrent gastric cancer. The regimen used in the study was comprised of two-week treatment cycles, with a withdrawal period between cycles. During treatment, patients were given either AO-90 (500-750 ml/day; AO/MF group) or a commercial amino acid solution (600-800 ml/day; C/MF group) by total parenteral nutrition (TPN) for 14 days concomitantly with MF therapy (5-fluorouracil 350 mg/m2/day, iv continuously for 14 days and mitomycin C 7 mg/m2, iv push on days 7 and 14). We interviewed 118 eligible and evaluable patients (72 men and 46 women; 59 cases in the AO/MF group and 59 in the C/MF group) about their quality of life immediately before the start of treatment, one week and two weeks after the start of treatment, and one week and two weeks after treatment. A 11-item questionnaire was used to interview the subjects: nine questions using a five-point scale, one question using a 100-mm linear visual analog scale, and one question using a five-grade face scale. Changes in the grades compared with baseline data were scored as 1 point (improvement of one grade or more, or 20 mm or more), 0 points (no changes), and-1 point (decline of one grade or more, or 20 mm or more). Before analyzing the significance, quality of life score data were adjusted by the Mantel-Haenszel method due to uneven distribution of subjects concerning baseline performance status and complications. Among the items questioned, subjects receiving AO-90 showed significantly higher scores in appetite, nausea, and ambulation at some evaluation time points than those receiving a methionine-containing TPN. The results show that AO-90 improved the quality of life of patients with advanced recurrent gastric cancer.

[A controlled study of AO-90, a methionine-free intravenous amino acid solution, in combination with 5-fluorouracil and mitomycin C in advanced gastric cancer patients (surgery group evaluation)]

The results of recent preclinical and clinical studies suggest that AO-90, a methionine-free intravenous amino acid solution (7.43%), potentiates the antitumor effect of 5-fluorouracil (5-FU). In the present multi-center, randomized, controlled study conducted at the surgery departments of 53 institutions between July 1991 and March 1993, patients with advanced gastric cancer were randomly allocated to receive either AO-90 (500-750 mL/day, AO/MF group) or Amiparen, a commercial intravenous amino acid solution (600-800 mL/day, C/MF group) by total parenteral nutrition for 14 days. Both groups received MF therapy which consisted of a continuous infusion of 5-FU at 350 mg/m2/day for 14 days and an i.v. push of mitomycin C 7 mg/m2 on days 7 and 14 (one course). Additional treatment courses were initiated after a withdrawal period when appropriate. Of the 138 subjects enrolled, 129 (93.5%) were eligible and 119 (86.2%) completed the scheduled treatment (AO/MF group: 57, C/MF group: 62). The overall clinical response rates in the completed cases were 26.3% (15/57) in the AO/MF group and 8.1% (5/62) in the C/MF group, and the difference between the groups was significant (p = 0.015). In particular, the response rate in the postoperative recurrent patients with measurable lesions was 42.9% (12/28) in the AO/MF group versus 12.0% (3/25) in the C/MF group (p = 0.016). Further, in the patients who were previously treated with fluoropyrimidine drugs, 29.0% (9/31) responded to the AO/MF therapy versus 8.6% (3/35) in the C/MF group (p = 0.053). The treatment-related adverse reactions observed were mainly hematologic and subjective/objective symptoms, such as decreased leukocyte count and hemoglobin level, nausea/vomiting and stomatitis. The differences in the incidence were not significant between the groups. Based on these results, AO-90 in the MF regimen appears to be effective in the treatment of patients with advanced gastric cancer by significantly potentiating the effects of 5-FU.

Relationships among the expression of epidermal growth factor receptor, proliferating cell nuclear antigen labeling index, and lymph node metastasis in gastric cancer

The expression of epidermal growth factor receptor (EGFR), epidermal growth factor (EGF), transforming growth factor alpha (TGF alpha) and the labeling index of proliferating cell nuclear antigen (PCNA LI) were examined immunohistochemically in 288 gastric cancer patients, and the relationships between these results and the lymph node metastasis were studied. To investigate the relation between the expression of EGFR and PCNA LI, we divided the patients into the following three groups according to the immunohistochemical findings: group A, EGFR (+); group B, EGFR (-), and EGF(+) or TGF alpha(+); group C, EGFR(-), EGF(-) and TGF alpha(-). In the cancers invading submucosal or proper muscle layer, high-PCNA tumors (PCNA LI > or = 70) in both groups A and B had more frequent lymph node metastasis than in the intermediate-(40-69) and low- (< or = 39) PCNA tumors. In the cancers invading subserosal layer or further, the frequency of metastasis in group A was over 78% and was not related to the PCNA range. In group B, metastasis was more frequent in high- and intermediate-PCNA tumors (about 80%) than in low-PCNA tumors (44%). These results suggest that growth regulation by EGFR is related to lymph node metastasis in gastric cancer, and the higher the PCNA LI of cancer cells becomes, the more frequent the occurrence of lymph node metastasis.

Expression of CD44 variant exons 8-10 in colorectal cancer and its relationship to metastasis

Splice variants of CD44 are overexpressed in human lung, breast, and colon carcinoma cell lines. This study was conducted to clarify the association between the expression of CD44 variant exons 8-10 and metastatic potential in human colorectal cancer. We found that the expression of a CD44 splice variant containing exons v8-10 was increased in all of 60 colorectal cancer specimens examined compared with matched normal colerectal mucosa, as determined by Northern blotting. Expression of CD44 variant exons 8-10 did not significantly correlate with histological type, depth of tumor invasion, lymphatic invasion, venous invasion, or lymph node metastasis. However, the level of CD44 variant exon 8-10 expression was significantly higher in carcinomas associated with liver metastasis than in those without liver metastasis. In addition, expression of CD44 variant exons 8-10 in the liver metastases was more intense than that in the primary colorectal cancers. These findings indicated that this domain of the CD44 glycoprotein encoded by exons v8-10 may play an important role in tumor hematogenous metastasis of human colorectal cancer.

Expression of human nm23-H1 and nm23-H2 proteins in hepatocellular carcinoma

BACKGROUND

The expression of nm23-H1 and nm23-H2 proteins in 25 hepatocellular carcinomas was studied immunohistochemically.

METHODS

Tissue specimens were reacted with anti-human nm23-H1 and nm23-H2 monoclonal antibodies (MoAb) (H1-229 and H2-206, respectively) and then stained by the biotin-streptoavidin complex method.

RESULTS

Adjacent nontumorous tissues were intensely stained with nm23-H1 and nm23-H2. Of the 25 hepatocellular carcinomas, 60% were positive for MoAb H1-229, and 68% were positive for MoAb H2-206. These immunoreactivities were most common in the cytoplasm of tumor cells. There was no significant correlation between the expression of nm23-H1 protein and tumor size, Edmondson's histopathologic classification, or invasion of the capsule. However, the authors observed an inverse relationship between nm23-H1 expression and intrahepatic metastases of hepatocellular carcinomas. There was no significant correlation between the expression of nm23-H2 protein and clinicopathologic findings. Only a short survival period was observed in patients with hepatocellular carcinoma with reduced nm23-H1 or nm23-H2 proteins.

CONCLUSIONS

The results suggest that nm23-H1 protein plays a role in the suppression of intrahepatic metastasis of hepatocellular carcinoma and that the combined expression of nm23-H1 is associated with favorable prognosis.

Overexpression of p53 protein and proliferative activity in colorectal adenoma

Overexpression of p53 was studied immunohistochemically in colorectal tumors. We found p53-positive cells in 17 (58.6%) of 29 specimens of cancer in adenoma. Expression of p53 protein was detected in the nuclei of the tumor cells. We also found p53-positive cells in 7 (7.1%) of 99 specimens of adenoma. p53 immunoreactivity for severe dysplasia was higher than that for mild or moderate dysplasia. p53 expression in adenomas was restricted to a few glands, and the proliferating-cell nuclear antigen (PCNA)-positive rate for the p53-positive glands was significantly higher than that for p53-negative glands. The results suggested that the p53-positive glands might have high growth fractions, and that immunohistochemical detection of p53 expression in tubular adenomas might contribute to identifying the potential for malignant transformation.

[Expression of human epidermal growth factor and its receptor of the gastric carcinomas with special reference to DNA ploidy patterns and nucleolar organizer regions]

In 68 cases of surgically resected gastric carcinomas, expression of human epidermal growth factor (EGF) and its receptor (EGFR) were examined immunohistologically using the Avidin-Biotin Peroxidase Complex Method, and their relation with DNA contents and nuclear protein synthesis in the tumor progression were studied by measuring DNA ploidy patterns and nucleolar organizer regions (NORs), respectively with cytofluorometry and AgNO3 stain method. EGF and EGFR expression were respectively found only in 2 (7%) and 1 (4%) in 28 early cancers, and significantly increased in advanced cancers, 25 (63%) and 9 (23%) out of 40 cases. The ratio of aneuploid tumor and the NORs numbers per tumor cell also increased in advanced cancers, compared with in early cancers. EGF and EGFR respectively expressed in 19 (51%) and 9 (23%) in 37 aneuploid cancers, significantly more frequent than 8 (26%) and 1 (3%) in 31 diploid cancers. In the EGF-positive tumors, the NORs numbers showed 4.11 +/- 0.72, significantly higher than 2.68 +/- 0.61 in the EGF-negative tumors. These results suggested that expression of EGF and EGFR in the gastric carcinomas increases during the tumor progression from the early to advanced stage, stimulates synthesis of DNA and nuclear protein, and consequently enhances (strengthens, heightens, or intensifies) the proliferative activity of the tumors.

Protein-tyrosine kinase p72syk is activated by thromboxane A2 mimetic U44069 in platelets

We show that p72syk is rapidly activated following the stimulation of thromboxane A2 mimetics, U44069 and STA2 in porcine platelets. The activity of p72syk reached a maximum at 10 s and decreased to a basal level within 60 s after 1 microM U44069 stimulation. This activation was enhanced in a dose-dependent manner and completely canceled by the pretreatment of platelet suspension with ONO3708, a specific antagonist of thromboxane A2. Pretreatment of platelets with aspirin as well as apyrase did not affect the activation of p72syk. When both extra- and intra-cellular Ca2+ were depleted, the activation of p72syk was still persistent; in contrast, the deactivation process was completely abrogated even at 120 s after U44069 stimulation. These results suggest that p72syk is a responsible enzyme to the protein-tyrosine phosphorylation events, and that p72syk functions mainly before Ca2+ recruitment in thromboxane A2-stimulated platelets.

Inverse association of nm23-H1 expression by colorectal cancer with liver metastasis

The expression of nm23-H1 mRNA and protein was studied in colorectal cancers by Northern blotting and immunohistochemistry. All 21 colorectal cancers studied by Northern blotting had increased levels of nm23-H1 mRNA relative to the adjacent normal colonic mucosa. Increased nm23-H1 protein expression was also observed in all 36 colorectal cancer cases including those studied by Northern blotting. There was no significant correlation between nm23-H1 expression and tumour histology, serosal invasion, lymphatic invasion, venous invasion, or lymph node metastasis. However, the expression of both mRNA and protein was significantly lower in tumours associated with liver metastasis than in those without such metastasis. These observations indicate that the nm23 gene may play a role in the suppression of liver metastasis of colorectal cancer.

Colonic prostaglandin-e2 in carcinogenesis in rats with N-methyl-n'-nitrosoguanidine

The effects of prostaglandin E2 and indomethacin on carcinogenesis were studied in male Wistar rats. Of the rats, those treated with MNNG (MNNG group) were given 1 ml of 0.1% solution of MNNG in distilled water by intrarectal instillation every day for 14 days. The diet for the rats treated with Indomethacin and MNNG (Indo-MNNG group) was supplemented with 0.005% indomethacin. No tumor was found in a group of controls. Tumor incidence was 43.8% at week 20 and 81.8% at week 40 of treatment for the MNNG group whereas, it was 5.3% at week 20 and 27.8% at week 40 for the Indo-MNNG group. These differences were of statistical significance (p<0.01). Tumor incidence per animal was lower for the Indo-MNNG group: a mean of 0.50 tumors/animal, compared with 2.18 tumors/animal for the MNNG group (p<0.01). PGE2 levels in colonic mucosa were: 23.9 (pg/mg total protein) at week 5: 27.8 at week 10; 33.2 at Week 20, and 34.8 at week 40 for the control group. It was 44.7 at week 5; 43.1 at week 10; 70.1 at week 20, and 79.7 at week 40 for the MNNG group. Intrinsic PGE2 levels in noncancerous mucosa were significantly higher for the MNNG group than for the control group at all stages of observation. PGE2 significantly decreased in the Indo-MNNG group. with mean values of 22.0 at week 5; 29.0 at week 10; 43.1 at week 20, and 40.6 at week 40, compared with the MNNG group. These findings demonstrated that PGE2 of colonic mucosa promoted the development and proliferation of carcinoma in MNNG-induced large bowel carcinogenesis in rats.

p53 immunoreaction in endoscopic biopsy specimens of colorectal cancer, and its prognostic significance

The expression of p53 protein was immunohistochemically studied in formalin-fixed paraffin-embedded biopsy specimens of 203 colorectal carcinomas by use of a monoclonal antibody specific for the p53 protein. PAb1801. p53 protein expression with its reactivity localised in nuclei was found in 121 (59.6%) of the cancers. There was no correlation of p53 immunoreactivity with histological classification, wall invasion, lymphatic invasion, venous invasion, lymph node metastases, or peritoneal metastases. p53-positive cancers were more frequently associated with liver metastasis than p53-negative ones. Patients with p53-positive tumours had significantly poorer prognoses than those with p53-negative tumours. The 5 year survival rate was 58.1% for patients with p53-positive tumours, and 76.3% for those with p53-negative tumours. In Dukes' stage C tumours, an especially good correlation was found between p53 immunoreactivity and prognosis. In addition, patients with p53-positive tumours had higher recurrence rates. The results indicate that p53 immunoreactivity may be a useful prognostic marker of colorectal cancers.

[Modes of spread and surgical strategy for gallbladder carcinoma with subserosal invasion]

The mode of spread and the prognosis were investigated in 22 patients with resected gallbladder carcinoma invading the subserosal layer. By the Kaplan-Meier method, the 5-year survival rate was 68.8% in patients receiving curative or relatively noncurative resection. On the other hand, no patient survived for more than 3 years after noncurative resection. The mode of subserosal infiltration was classified according to the general rules for gastric cancer study. At least systemic lymph node dissection (R2) should be performed in patients with ss alpha cancer, because lymph node metastasis in these patients were confined to the 1st group. More extensive lymph node dissection (R2 with 9, 16) is essential for patients with ss beta and ss gamma, because lymph node metastasis to at least the 2nd group were seen in 75% of them. The surgical margin was positive for cancer in all patient with infiltration of the hepatoduodenal ligament. Therefore, it was considered that hepatoligamentectomy should be performed in these patients to obtain a cancer free surgical margin. Among patients undergoing curative or relatively noncurative resection, the recurrence rate was 43% in those with lymph node metastasis and 50% in those with DNA aneuploidy. Therefore, it appears that adjuvant chemotherapy should be given to such patients.

Dimethyl sulfoxide (DMSO) increases expression of sialyl Lewis x antigen and enhances adhesion of human gastric carcinoma (NUGC4) cells to activated endothelial cells

Dimethyl sulfoxide (DMSO) exerts a number of biological effects including the promotion of cell differentiation in cultured cells. In this study, we examined the effect of DMSO on the adhesion of tumor cells to endothelial cells. In vitro treatment of human gastric adenocarcinoma (NUGC4) cells with DMSO resulted in increased adhesion to interleukin-I (IL-I)-activated human endothelial cells compared with DMSO-untreated NUGC4 cells. In flow cytometry, treating NUGC4 cells with DMSO enhanced the expression of sialyl Lewis x (sialyl Le(x)) and sialyl dimeric Le(x) antigens on their surface. Also, the binding of Limulus polyphemus agglutinin (LPA), which specifically binds to cell-surface sialic acids, was increased by DMSO. The adhesion of DMSO-treated NUGC4 cells to activated endothelial cells was blocked by neuraminidase pre-treatment of tumor cells or by antibody against either endothelial leukocyte adhesion molecule-I (ELAM-I) or sialyl Le(x). Thus, it is suggested that enhanced adhesion following DMSO treatment is mediated by the interaction of sialyl Le(x) expressed on NUGC4 cells with ELAM-I of endothelial cells. The modulation of sialyl Le(x) antigen by DMSO provides a useful system for studying the regulatory mechanism of Lewis-related carbohydrate antigens and also for understanding the metastatic properties of cancer cells.