Thoracoscopic esophagectomy with extended lymph node dissection in the left lateral position: technical feasibility and oncologic outcomes.

The aim of this study was to estimate the technical and oncologic feasibility of video-assisted thoracoscopic radical esophagectomy (VATS) in the left lateral position. From January 2003 to December 2011, 132 patients with esophageal cancer underwent VATS. The mean duration of the thoracic procedure and the entire procedure was 294 ± 88 and 623 ± 123 minutes, respectively. Mean blood loss during the thoracic procedure and the entire procedure was 313 ± 577 and 657 ± 719 g, respectively. The mean number of dissected thoracic lymph nodes was 32.6 ± 12.9. There were four in-hospital deaths (3.0%); two patients (1.5%) died of acute respiratory distress syndrome and two patients (1.5%) died of tumor progression. Postoperative unilateral or bilateral recurrent laryngeal nerve (RLN) palsy, or pneumonia was found in 33 (25.0%), 21 (15.9%), and 27(20.5%) patients, respectively. The patients were divided into the first 66 patients who underwent VATS (Group 1) and the subsequent 66 patients (Group 2). The numbers of cases who underwent neoadjuvant or induction chemotherapy for T4 tumor and intrathoracic anastomosis were higher in Group 2 than in Group 1. The duration of the procedure, amount of blood loss, and the number of dissected thoracic lymph nodes were not different between the two groups. The total number of dissected lymph nodes was higher in Group 2 than in Group 1 (72.6 ± 27.8 vs. 62.6 ± 21.6, P = 0.023). The rate of bilateral RLN palsy was less in Group 2 than in Group 1 (7.6% vs. 24.2%, P = 0.042). The mean follow-up period was 38.7 months. Primary recurrence consisted of hematogenous, lymphatic, peritoneal dissemination, pleural dissemination, and locoregional in 15 (11.3%), 20 (15.1%), 3 (2.3%), 4 (3.0%), and 5 patients (3.8%), respectively. The rate of regional lymph node recurrence within the dissection field was only 4.5%. The prognosis of patients with lymph node metastasis was significantly poorer than that of patients without lymph node metastasis. However, the prognosis of the 11 cases that had metastasis only around RLNs was similar to that of node-negative cases. Thirteen patients with pathological remnant tumor (R1 or R2) did not survive longer than 5 years at present. The overall 5-year survival rate of stage I, II, and III disease after curative VATS was 82.2%, 77.0%, and 52.3%, respectively. Expansion of VATS criteria for patients after induction chemotherapy for T4 tumor or thoracoscopic anastomosis did not adversely affect the surgical results by experience. Although the VATS procedure is accompanied by a certain degree of morbidity including RLN palsy and pulmonary complications, VATS has an excellent locoregional control effect. In addition, the favorable survival after VATS shows that the procedure is oncologically feasible.

Prospective randomized controlled study on the effects of perioperative administration of a neutrophil elastase inhibitor to patients undergoing video-assisted thoracoscopic surgery for thoracic esophageal cancer.

Sivelestat sodium hydrate (Ono Pharmaceutical Co., Osaka, Japan) is a selective inhibitor of neutrophil elastase (NE) and is effective in reducing acute lung injury associated with systemic inflammatory response syndrome (SIRS). We conducted a prospective randomized controlled study to investigate the efficacy of perioperative administration of sivelestat sodium hydrate to prevent postoperative acute lung injury in patients undergoing thoracoscopic esophagectomy and radical lymphadenectomy. Twenty-two patients with thoracic esophageal cancer underwent video-assisted thoracoscopic esophagectomy with extended lymph node dissection in our institution between April 2007 and November 2008. Using a double-blinded method, these patients were randomly assigned to one of two groups preoperatively. The active treatment group received sivelestat sodium hydrate intravenously for 72 hours starting at the beginning of surgery (sivelestat-treated group; n= 11), while the other group received saline (control group; n= 11). All patients were given methylprednisolone immediately before surgery. Postoperative clinical course was compared between the two groups. Two patients (one in each group) were discontinued from the study during the postoperative period because of surgery-related complications. Of the remaining 20 patients, 2 patients who developed pneumonia within a week after surgery were excluded from some laboratory analyses, so data from 18 patients (9 patients in each group) were analyzed based on the arterial oxygen pressure/fraction of inspired oxygen ratio, white blood cell count, serum C-reactive protein level, plasma cytokine levels, plasma NE level, and markers of alveolar type II epithelial cells. In the current study, the incidence of postoperative morbidity did not differ between the two groups. The median duration of SIRS in the sivelestat-treated group was significantly shorter than that in the control group: 17 (range 9-36) hours versus 49 (15-60) hours, respectively (P= 0.009). Concerning the parameters used for the diagnosis of SIRS, the median heart rates on postoperative day (POD) 2 were significantly lower in the sivelestat-treated group than in the control group (P= 0.007). The median arterial oxygen pressure/fraction of inspired oxygen ratio of the sivelestat-treated group were significantly higher than those of the control group on POD 1 and POD 7 (POD 1: 372.0 [range 284.0-475.0] vs 322.5 [243.5-380.0], respectively, P= 0.040; POD 7: 377.2 [339.5-430.0] vs 357.6 [240.0-392.8], P= 0.031). Postoperative white blood cell counts, serum C-reactive protein levels, plasma interleukin-1beta, tumor necrosis factor-alpha levels, and plasma NE levels did not differ significantly between the two groups at any point during the postoperative course, nor did serum Krebs von den Lungen 6, surfactant protein-A, or surfactant protein-D levels, which were used as markers of alveolar type II epithelial cells to evaluate the severity of lung injury. Plasma interleukin-8 levels were significantly lower in the sivelestat-treated group than in the control group on POD 3 (P= 0.040). In conclusion, perioperative administration of sivelestat sodium hydrate (starting at the beginning of surgery) mitigated postoperative hypoxia, partially suppressed postoperative hypercytokinemia, shortened the duration of SIRS, and stabilized postoperative circulatory status after thoracoscopic esophagectomy.

Learning of thoracoscopic radical esophagectomy: how can the learning curve be made short and flat?

Attainment of proficiency in video-assisted thoracoscopic radical esophagectomy (VATS) for thoracic esophageal cancer requires much experience. We have mastered this procedure safely under the direction of an experienced surgeon. After adoption of the procedure, the educated surgeon directed induction of this surgical procedure at another institution. We evaluated the efficacy of instruction during the induction period by comparing the results at the two institutions in which VATS had been newly induced. We defined the induction period as the time from the beginning of VATS to the time when the last instruction was carried out. From January 2003 to December 2007, 53 patients were candidates for VATS at Kanazawa University (institution 1). Of these, 46 patients underwent curative VATS by a single operator. We divided this period into three parts: the induction period of VATS, post-induction period, and proficient period when the educated surgeon of institution 1 directed the procedure at Maebashi Red Cross Hospital (institution 2). At institution 1, 12 VATS were scheduled, and nine procedures (75%) (group A) including eight instructions were completed during the induction period (from January 2003 to August 2004). Thereafter, VATS was performed without instruction. In the post-induction period, nine VATS were scheduled, and eight procedures (88.8%) (group B) were completed from September 2004 to August 2005. Subsequently, 32 VATS were scheduled, and 29 procedures (90.6%) (group C) were completed during the proficient period (from September 2005 to December 2007). The surgeon at Maebashi Red Cross Hospital (institution 2) started to perform VATS under the direction of the surgeon who had been educated at institution 1 from September 2005. VATS was completed in 13 (76.4%) (group D) of 17 cases by a single surgeon including seven instructions during the induction period at institution 2 from September 2005 to December 2007. No lethal complication occurred during the induction period at both institutions. We compared the results of VATS among four groups from the two institutions. There were no differences in the background and clinicopathological features among the four groups. The number of dissected lymph nodes and amount of thoracic blood loss were similar in the four groups (35 [22-52] vs 41 [26-53] vs 32 [17-69] vs 29 [17-42] nodes, P = 0.139, and 170 [90-380] vs 275 [130-550] vs 220 [10-660] vs 210 [75-543] g, P = 0.373, respectively). There was no difference in the duration of the thoracic procedure during the induction period at the two institutions. However, the duration of the procedure was significantly shorter in the proficient period of institution 1 (group C: 266 [195-555] minutes) than in the induction period of both institutions (group A: 350 [280-448] minutes [P = 0.005] and group D: 345 [270-420] mL [P = 0.002]). There were no surgery-related deaths in any of the groups. The incidence of postoperative complications did not differ among the four groups. Thoracoscopic radical esophagectomy can be mastered quickly and safely with a flat learning curve under the direction of an experienced surgeon. The educated surgeon can instruct surgeons at another institution on how to perform thoracoscopic esophagectomy. The operation time of thoracoscopic surgery is shortened by experience.

Von Willebrand Factor Deposition and ADAMTS-13 Consumption in Allograft Tissue of Thrombotic Microangiopathy-like Disorder After Living Donor Liver Transplantation: A Case Report.

BACKGROUND: Thrombotic microangiopathy (TMA) pathogenesis after living donor liver transplantation (LDLT) is thought to be caused by release of unusually large von Willebrand factor multimers (UL-vWFMs) resulting from sinusoidal endothelial cell damage and induction of platelet adhesion and aggregation. A decrease in a disintegrin-like and metalloproteinase with thrombospondin type 1 motifs-13 (ADAMTS-13) that cleave UL-vWFMs might cause excessive UL-vWFMs activity and result in platelet thrombus formation. However, this phenomenon has not undergone a full pathologic assessment. PROCEDURES: A 60-year-old man was diagnosed with hepatitis C-related end-stage cirrhosis. His son was the donor, and he underwent LDLT. On postoperative day 44, his laboratory findings met most TMA diagnostic criteria, and he was diagnosed with TMA-like disorder (TMALD). Localization of CD42b as a platelet marker, vWF, and ADAMTS-13 in allograft tissue of this patient were evaluated using immunohistochemistry. RESULTS: CD42b expression was observed as platelet aggregates attached to hepatocytes or within the hepatocyte cytoplasm, a morphology called extravasated platelet aggregation (EPA). vWF expression was observed mainly as deposited compact clusters, and ADAMTS-13 expression resembled distinct dots throughout the liver tissue. CONCLUSION: These findings suggest that EPA indicated sinusoidal endothelial cell damage followed by detachment, and vWF deposition resulted from UL-vWFM oversynthesis. ADAMTS-13 might be consumed in the allograft tissue to cleave UL-vWFMs, but ADAMTS-13 levels might be insufficient to cleave all the deposited UL-vWFMs. We present the case of an LDLT recipient diagnosed with TMALD using blood tests, which showed the presence of TMA pathogenesis in the allograft.

Evaluation of immunoreactivity for erbB-2 protein as a marker of poor short term prognosis in gastric cancer.

Using a polyclonal antibody that is monospecific for the erbB-2 oncogene product, an immunohistochemical study of the expression of erbB-2 protein was performed in formalin-fixed paraffin-embedded tissue sections from 260 primary gastric cancers. erbB-2 protein expression in which the reaction was localized to the cell membranes was observed in 31 (11.9%) cancers. All nontumor cells and normal gastric epithelium were negative for membrane staining. There was not a significant association between erbB-2 staining and histological type or venous invasion. erbB-2 protein expression was associated with serosal invasion, lymph node metastasis, and lymphatic invasion. In addition, erbB-2 protein expression correlated with a high number of lymph node metastases. Furthermore, the risk of recurrence in lymph node was over 3 times higher in patients with erbB-2 protein-positive tumors than in those with erbB-2 protein-negative ones. When erbB-2 protein expression and the clinical parameters were entered simultaneously into the Cox regression model, erbB-2 protein expression emerged as an independent prognostic indicator. Patients with erbB-2 protein-positive tumors had 5-fold greater relative risk of death, as compared with those with erbB-2 protein-negative tumors. These results indicate that erbB-2 protein expression is an important independent prognostic indicator in gastric cancer. The high malignant potential of erbB-2 protein-positive tumors may be associated with the very high potential for lymph node metastasis.

Ischemia reperfusion-facilitated sinusoidal endothelial cell injury in liver transplantation and the resulting impact of extravasated platelet aggregation.

BACKGROUND: The exact sequence of events leading to ultimate hepatocellular damage following ischemia/reperfusion (I/R) is incompletely understood. In this article, we review a mechanism of organ dysfunction after hepatic I/R or immunosuppressive treatment, in addition to the potential of liver sinusoidal endothelial cell (LSEC) protection and antiplatelet treatment for the suppression of hepatocellular damage. METHODS: A review of the literature, utilizing PubMed-NCBI, was used to provide information on the components necessary for the development of hepatocellular damage following I/R. RESULTS: It is well-established that LSECs damage following hepatic I/R or immunosuppressive treatment followed by extravasated platelet aggregation (EPA) is the root cause of organ dysfunction in liver transplantation. We have classified three phases, from LSECs damage to organ dysfunction, utilizing the predicted pathogenic mechanism of sinusoidal obstruction syndrome. The first phase is detachment of LSECs and sinusoidal wall destruction after LSECs injury by hepatic I/R or immunosuppressive treatment. The second phase is EPA, accomplished by sinusoidal wall destruction. The various growth factors, including thromboxane A2, serotonin, transforming growth factor-beta and plasminogen activator inhibitor-1, released by EPA in the Disse's space of zone three, induce portal hypertension and the progression of hepatic fibrosis. The third phase is organ dysfunction following portal hypertension, hepatic fibrosis, and suppressed liver regeneration through various growth factors secreted by EPA. CONCLUSION: We suggest that EPA in the space of Disse, initiated by LSECs damage due to hepatic I/R or immunosuppressive treatment, and activated platelets may primarily contribute to liver damage in liver transplantation. Endothelial protective therapy or antiplatelet treatment may be useful in the treatment of hepatic I/R following EPA.

Inverse expression of S100A4 and E-cadherin is associated with metastatic potential in gastric cancer.

S100A4 is known to be involved in cancer cell motility by virtue of its ability to activate nonmuscle myosin. E-cadherin has an important role in the homophilic cell-cell adhesion and is called an invasion suppressor gene. In the current study, we investigate the histological type and metastatic potential of gastric cancer from the aspect of the interrelationship of E-cadherin and S100A4 expression. Expression of E-cadherin and S100A4 in gastric cancer cell lines, primary gastric cancers, and their normal counterparts were analyzed by reverse transcription-PCR, Western blot, and immunohistochemical methods. S100A4 protein and E-cadherin were expressed in five of eight gastric cancer cell lines, and inverse expression of the two proteins are found in four cell lines. In the clinical specimens, E-cadherin mRNA expression in differentiated adenocarcinomas (88%, 14 of 16) was significantly more frequent than that in poorly differentiated adenocarcinomas (50%, 22 of 44; P = 0.015). Western blot analysis demonstrates that S100A4 protein expression in poorly differentiated adenocarcinomas was 1.6-fold higher than in well differentiated adenocarcinoma. Immunohistochemically, S100A4 expression was detected in 51 (55%) of 92 primary gastric cancers. Reduced expression of E-cadherin in primary tumors was found in 66 (72%) of 92 tumors. S100A4 expression in the poorly differentiated adenocarcinomas had a strong relation to positive lymph node involvement or peritoneal dissemination. Reduced E-cadherin expression showed a strong relationship with positive serosal involvement and infiltrating type. Tumors classified as a group with reduced E-cadherin and high expression of S100A4 reveal positive peritoneal dissemination, serosal involvement, and infiltrating type in the growth pattern. Furthermore, these tumors showed a strong correlation with the poorly differentiated adenocarcinoma. In contrast, tumors with preserved E-cadherin and low expression of S100A4 have a close relation to the well differentiated adenocarcinoma and a favorable prognosis. By the Cox proportional hazard model, S100A4 and E-cadherin tissue status was judged as an independent prognostic factor. S100A4 and E-cadherin tissue status may be a powerful aid in evaluating metastatic potential or the prognosis of patients with gastric cancer.

Role of vascular endothelial growth factor C expression in the development of lymph node metastasis in gastric cancer.

Neogenesis of lymphatic vessel and lymphatic invasion is frequently found in the stroma of cancers, but the mechanisms of this phenomenon remain unclear. Vascular endothelial growth factor C (VEGF-C) is known to be the only growth factor for the lymphatic vascular system, and its receptor has been identified as Flt4. To clarify the mechanism of lymphatic invasion in cancer, we studied the expression of VEGF-C and flt4 genes in gastric cancer tissues. VEGF-C mRNA was mainly expressed in primary tumors (15 of 32; 47%), but the frequency of VEGF-C mRNA expression was low in normal mucosa (4 of 32; 13%). In primary tumors, there was a significant relationship between VEGF-C and flt4 mRNA expression. In contrast, Flt4 was mainly expressed on the lymphatic endothelial cells but not in cancer cells. A strong correlation was found between VEGF-C expression and lymph node status, lymphatic invasion, venous invasion, and tumor infiltrating patterns. Cancer cells in the lymphatic vessels frequently showed intracytoplasmic VEGF-C immunoreactivity. Furthermore, there was a close correlation between VEGF-C tissue status and the grade of lymph node metastasis. Patients with high expression of VEGF-C protein had a significantly poorer prognosis than did those in low VEGF-C expression group. By the Cox regression model, depth of wall invasion, lymph node metastasis, and VEGF-C tissue status emerged as independent prognostic parameters, and the VEGF-C tissue status was ranked third as an independent risk factor for death. These results strongly suggest that cancer cells producing VEGF-C may induce the proliferation and dilation of lymphatic vessels, resulting in the development of invasion of cancer cells into the lymphatic vessel and lymph node metastasis.

Efficacy of conversion gastrectomy following docetaxel, cisplatin, and S-1 therapy in potentially resectable stage IV gastric cancer.

BACKGROUND: Recent advances in gastric cancer chemotherapy have made macroscopic complete resection possible in some patients with stage IV disease. METHODS: We retrospectively investigated the efficacy of multimodal therapy with combined docetaxel, cisplatin, and S-1 (DCS) and conversion gastrectomy in 57 patients with stage IV gastric cancer. RESULTS: Of the 57 patients, 15 patients were categorized into potentially resectable case, which is defined as patients with single incurable factor including the upper abdominal para-aortic lymph node metastasis (16a2b1 PAN metastasis) or fewer than three peripheral liver metastases. The other 42 were categorized as initially unresectable. All of patients underwent DCS therapy, and then 34 patients underwent conversion gastrectomy. The 3-year overall survival (OS) rate among the patients who underwent conversion gastrectomy was 50.1% with MST of 29.9 months. They had significantly longer OS than patients who underwent DCS therapy alone (p < 0.01). Univariate analysis among the patents with conversion gastrectomy identified 16a2b1PAN metastasis, peritoneal metastasis, potential resectable case, R0 resection as significant prognostic factors. A 3-year OS in potential resectable cases was 92.9%. Multivariate analysis identified potential resectability as the only independent prognostic factor contributing to OS (HR 0.133, 95%CI 0.024-0. 744, p = 0.021). In contrast, clinical response was selected as the only independent prognostic factor in the subgroup of initially unresectable cases (HR 0.354, 95%CI 0.151-0.783, p = 0.021). CONCLUSION: Patients with potentially resectable disease had a remarkably good prognosis among stage IV gastric cancer patients, and might be ideal candidates for conversion gastrectomy following DCS therapy.

Membrane-type 1 matrix metalloproteinase enhances lymph node metastasis of gastric cancer.

The mechanisms of the lymph node metastasis remain unclear. We demonstrate the role of MT1-MMP on the lymph node metastasis using in vivo experimental model of lymph node metastasis by orthotopic implantation of MT1-MMP transfected gastric cancer cell line in the stomach of nude rats. TMK-1 cell line without expression of MT1-MMP was transfected with the pcDNA3 plasmid containing a 3.4-kb MT1-MMP cDNA fragment by calcium phosphate method, and the transfected cell line was designated as TMK-MT. Western blot and RT-PCR analyses showed the specific bands corresponding to MT1-MMP in the TMK-MT cells. By gelatin zymography, the activated form (62-kDa) of MMP-2 was identified in the medium of TMK-MT cell line, but was not detected in TMK-1 cells. Six weeks after orthotopic implantation of TMK-1 and TMK-MT xenografts of nude mouse-subcutaneus tumor into the stomach of nude rats, gastric tumors were found in all the animals. Histologically, the lymphatic invasion was found in the submucosa of the TMK-MT gastric tumors. Lymph node metastasis was not detected in nude rats bearing TMK-1 gastric tumor (0/8). In contrast, lymph node metastasis was detected in five out of 8 rats, bearing TMK-MT gastric tumor. MT1-MMP immunoreactivity was found on the cell membrane and cytoplasm of TMK-MT cells not only in the lymph node metastasis but also in the stomach tumor. These results suggest that MT1-MMP overexpression induced by transfection of its gene may promote lymph node metastasis of transformed cells.

Lymphangiogenesis and the vascular endothelial growth factor receptor (VEGFR)-3 in gastric cancer.

Vascular endothelial growth factor C (VEGF-C) is the only factor known to cause lymphangiogenesis. We studied the correlation between VEGF-C and vascular endothelial growth factor receptor-3 (VEGFR-3) expression of 85 primary gastric cancers by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry, and the results were correlated with the number of lymphatic vessels, stained with anti-VEGFR-3 antibody. RT-PCR and immunohistology demonstrated that VEGF-C was mainly produced from cancer cells, but not from stromal elements. Morphologically, VEGFR-3 expression was detected in the endothelial cells of the stromal lymphatic vessels. There was a statistically positive correlation between the incidence of VEGF-C and VEGFR-3 mRNA expression in the primary tumours (P=0.0002). The number of VEGFR-3-positive lymphatic vessels in VEGF-C mRNA positive tumours was significantly larger than that in VEGF-C-negative tumours. The number of VEGFR-3-positive vessels in the tumour stroma was closely related to the grade of lymphatic invasion of gastric cancer. These results strongly indicate that VEGF-C may induce the proliferation of lymphatic vessels in the stroma of primary gastric cancer via activation of VEGFR-3, expressed on the endothelial cells of lymphatic vessels. In these circumstances, cancer cells can easily invade the lymphatic vessel, because of the increase of the contact points of cancer cells with the lymphatic vessels.

Activation of immediate early gene, c-fos, and c-jun in the rat small intestine after ischemia/reperfusion.

BACKGROUND: Activated immediate early genes (IEGs) play key roles in mediating cellular response after ischemia/reperfusion (I/R) injuries in some organs such as liver, heart and kidney. However, there is no report investigating an association between the activation of IEGs and cellular regeneration or programmed cell death after I/R in small intestine. METHODS: We examined a sequential expression of c-fos and c-jun after I/R in rat small intestine using reverse transcription-polymerase chain reaction and Northern blot analysis, and compared the patterns with coexistent two parameters: (1) regeneration determined by immunohistochemical detection of proliferating cell nuclear antigen, (2) programmed cell death determined with the terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end-labeling (TUNEL) method and DNA fragmentation. RESULTS: The expression of c-fos and c-jun mRNA increased markedly 15 min after reperfusion and was, respectively, 6.3 and 4.4 times higher than in controls. Proliferating cell nuclear antigen expression was significantly elevated between 5 min and 4 hr, peaking at 30 min after reperfusion. Apoptosis showed a peak 60 min after reperfusion. Apoptosis after I/R was detected in the nuclei of absorptive epithelial cells by the TUNEL method, and these apoptotic signals were consistent with the expression of c-Fos and c-Jun proteins using an immunohistochemical method. CONCLUSIONS: These results suggest that overexpression of c-fos and c-jun after I/R in the small intestine correlates with programmed cell death and subsequent cellular regeneration.

Human nm23-h1-protein and h2-protein have similar nucleoside diphosphate kinase-activities.

The nucleoside diphosphate kinase activity of nm23-H1 and nm23-H2 proteins was examined. Full length nm23-H1 and nm23-H2 proteins were produced in E.coli in fusion form with a 26 kDa glutathione S-transferase (GST). Affinity purified nm23-H1 and nm23-H2 formed phosphoenzyme intermediates when incubated with [gamma-P-32]ATP. The formation of GTP from GDP was also demonstrated by these two proteins by thin layer chromatography. The 26 kDa GST alone did not show similar activity. Both nm23-H1 and nm23-H2 shared very similar biochemical characteristics, namely, time kinetics, pH, temperature and cation dependency for the formation of the phosphoenzyme intermediates.

Over-expression of p53 protein in gastric adenoma and cancer.

Recently, alterations of p53 gene in gastric cancer have been reported by several authors, but the role of p53-gene alterations in early step of carcinogenesis of gastric cancer remains unclear. To assess whether p53 expression is an early event in the carcinogenesis of gastric cancer, 402 gastric tumors (14 hyperplastic polyps, 48 gastric adenomas, 340 gastric cancers) were analyzed by immunohistochemistry using the specific antibody, PAb1801, against p53 oncoprotein. Five (15%) of 34 adenomas and 110 (32%) of 340 gastric cancers showed a definite positive nuclear staning for p53 protein. In contrast, the anti-p53 MAb did not show any specific staining in normal gastric epithelial cells, intestinal metaplasia or hyperplastic polyps. Out of nine adenomas showing mild dysplasia, only one tumor (11%) showed p53 expression. In contrast, 4 (16%) of 25 adenomas showing moderate dysplasia revealed positive p53 expression. In addition, positive p53 staining was not found in adenomas less than 1 cm in diameter, but five (25%) of 20 adenomas 1 cm or more in diameter showed definite p53-staining. In this way, the positive-p53 tissue status in adenomas was correlated with the dysplastic grade and size of adenomas. The incidence of positive-p53 immunoreaction in the differentiated type of cancers was 35% and showed no relation to wall invasion. On the contrary, p53 expression in the undifferentiated type of m-cancers, in which tumor invasion was limited to the mucosal layers, was detected in only one (5%) of 21 cases. Among undifferentiated type of gastric cancer, however, deeply invasive cancers showed higher p53-positive rate, as compared with m-cancer. These results may suggest p53 gene activation at a relatively early stage of the adenoma-carcinoma sequence, leading to the development of some differentiated adenocarcinomas in the stomach.

Expression of hepatocyte growth factor(hgf) and C-met gene in human gastric-cancer cell-lines.

It has become evident that the hepatocyte growth factor (HGF) could be involved in the growth of various epithelial cells. In addition, it has recently been elucidated that the c-met gene, a proto-oncogene, encodes the HGF receptor. We examined the expression of HGF and c-met gene in human gastric cancer, using seven gastric cancer cell lines. The Northern blotting method revealed that, among seven cell lines used, only MKN45 expressed the c-met gene at a high efficiency, while the Southern blotting method demonstrated the amplification of the c-met gene. When the expression of HGF gene was studied by the Northern blot method, the expression of this gene was also observed only in MKN45, which was confirmed by immunostaining with polyclonal antibodies to HGF. The above results suggest the possibility that in MKN45, a gastric cancer cell line, the autocrine mechanism by HGF-met might be involved in its growth.

Frequent p53 mutations on exons-5 and exon-8 in human primary gastric-cancer.

The frequency of p53 mutations in human primary gastric cancer was analyzed. RNA was extracted from 30 primary cancer tissues and RT-PCR was performed to amplify p53 cDNA. Codons 114 to 325 of p53, where well conserved and frequently mutating areas reside, were amplified using three sets of primers. RT-PCR products were analyzed for the presence of mutations by single strand conformation polymorphism assays. Sixteen of primary cancer samples showed shifted mobility in at least one of the analyzed areas. Sequence analysis confirmed the presence of p53 mutations in all samples with shifted mobility in single strand conformation polymorphism assays. Fourteen of the thirty samples had amino acid substitutions due to point mutations and/or frame shifts. Two samples had only a nonsense point mutation. Mutations were clustered in two different areas of die p53 gene, codons 135 to 185 on exon 5 and codons 261 to 285 on exon 8, with a diversity of mutation patterns. A simultaneously and independently performed immunohistochemical study of p53 expression in these cancer tissues showed a relatively good, but not an absolute, correlation with the presence of the mutated p53. The p53 mutation appears to be the first major alteration of cellular genes in human primary gastric cancer.

Decreased expression of p16 gene in gastric cancer.

We analyzed gastric cancers for p16 gene alterations. Homozygous deletion of the p16 gene was found in 1 of 8 gastric cancer cell lines and none of 20 primary gastric cancers. Mutations of the p16 gene were not detected in exon 1-3. Reverse transcription-polymerase chain reaction (RT-PCR) analysis showed decreased or no expression of the p16 gene in 1 of 8 cell lines (12.5%) and in 8 of 20 tumors (40%), although no homozygous deletions or mutations within exon 1-3 were detected. These results suggest that the p16 gene may correlate to tumorigenesis due to decrease or loss of gene products in gastric cancers.

Evidence of autocrine mechanism in poorly differentiated adenocarcinoma of the stomach.

To evaluate a potential role of an autocrine mechanism in gastric cancer, we carried out an immunohistochemical study of epidermal growth factor (EGF), transforming growth factor alpha (TGFalpha), and epidermal growth factor receptor (EGFR) in 167 primary gastric cancer tissues. Slot blot hybridization was also performed to detect the amplification of EGFR gene. Immunohistochemically, 70 (42%), 87 (52%), 68 (41%) of 167 primary gastric cancers were stained positively for EGF, TGFalpha, and EGFR, respectively. Tumors with synchronous expression of EGFR and its ligands were most frequent in the following clinicopathological groups: tumors greater than 6 cm in size, those of the infiltrating type, and those of the poorly differentiated type. Among poorly differentiated carcinomas, the synchronous expression of EGFR and its ligands was more frequent in the infiltrating gross type than in the localized type. EGFR gene amplification was found in 5 (4.9%) of 103 primary tumors. EGFR gene amplification was also observed more frequently in infiltrating gross type of poorly,differentiated adenocarcinomas, as compared to localized gross type. These results indicate that the autocrine mechanism through EGFR may play an important role in the progression of infiltrating gross type of poorly differentiated adenocarcinoma of the stomach.

Human pancreatic cancer cells disable function of Fas receptors at several levels in Fas signal transduction pathway.

The aims of this study were to evaluate the functional expression of Fas receptors (Fas) in human pancreatic cancer cell lines; Capan-1, AsPC-1, BxPC-3, PANC-1, and MIA PaCa-2 and to search for the mechanisms of receptor-mediated inhibition of Fas signaling in these cells. Despite the expression of Fas receptors at considerable levels, exposure of these cells to agonistic Fas antibodies (500 ng/ml) induced only minimal apoptosis in 4 cell lines. The mechanisms allowing resistance to Fas-mediated apoptosis are complex. Using RT-PCR, we identified molecules which might counteract the apoptogenic signal at several levels of Fas signal transduction pathway. The most striking findings were the overexpression of Fas decoy receptors (DcR3), Fas associated phosphatase-1 (FAP-1), and FLICE-inhibitory protein (c-FLIP) in the resistant cell lines as well as in pancreatic cancer surgical specimens. In conclusion, pancreatic cancer cells express three molecules that can abrogate Fas function at different levels of Fas signaling cascade, resulting in resistance to Fas-mediated apoptosis, and this may promote the progression of this malignancy.