[Contribution of carbohydrate antigens to endothelial E-selectin binding in cancer cells]

We first investigated the difference in carbohydrate antigens' expression between primary tumors and matched metastatic liver lesions of colorectal carcinomas, using immunohistochemical methods. Regarding the degree of expression, SLA, SLX and SPan-1 antigens were found to be expressed on a larger proportion of tumor cells in liver metastases than in primary tumors. Second, comparing the expression of carbohydrate antigens on highly metastatic colon cancer cell line to the parental line, the expression of SLA on the surface of highly metastatic variant was increased more intensively than the parental line. Finally, we investigated the contribution of carbohydrate antigens to endothelial E-selectin binding in colon and pancreatic cancer cells, and the results indicated that SLA might play a significant role in this binding. These findings suggest that the expression of carbohydrate antigens on the surface of cancer cells obviously contributed to E-selectin binding and also to metastatic potential.

Intracellular alkalosis during hypoxia in newborn mouse brain in the presence of systemic acidosis: a phosphorus magnetic resonance spectroscopic study

We investigated the in vivo changes in cerebral energy metabolism and pHi in newborn mice noninvasively during 8 h of hypoxia with FiO2 = 5%, using phosphorus magnetic resonance spectroscopy continuously. The intracellular brain pH (pHi) increased from 7.20 +/- 0.03 to 7.36 +/- 0.03 (P < 0.05) at 1 h of hypoxia and then decreased gradually. On the other hand, the mixed arterial and venous blood pH decreased gradually during hypoxia, reaching a minimum value of 7.16 +/- 0.01 at the end of the hypoxia. There was no significant difference in PCO2 between control (47.4 +/- 0.8 mm Hg) and 1-h hypoxic (49.0 +/- 1.1 mm Hg) mice. The blood glucose concentration was significantly increased at 1 h of hypoxia. These results indicate that the alkaline shift in pHi during hypoxia was caused neither by systemic alkalosis due to hypocapnia nor hypoglycemia.

Erythrocyte sodium-potassium transport in hyperkalaemic and normokalaemic infants

One of the causes of early onset hyperkalaemia in very low birth weight infants is presumed to be the dysfunction of K+ transport across the cell membrane. Sodium-potassium adenosine triphosphatase(Na(+)-K+ ATPase) is known to play a major role in K+ transport. We compared the concentrations of erythrocyte Na(+)-K+ ATPase (Vmax levels) for hyperkalaemic and normokalaemic infants of matched gestational age. In hyperkalaemic infants, the highest levels of Vmax were reached at 24-48 h after birth, but in normokalaemic infants, there were no significant changes in Vmax levels during the 1st week after birth. At 12-72 h after birth, erythrocyte K+ concentrations for hyperkalaemic infants were higher than those of normokalaemic infants. For both groups of infants, the highest levels of plasma K+ during the 1st week after birth showed a positive correlation with those of Vmax.

CONCLUSION

Na(+)-K+ ATPase on the cell membrane is activated to compensate for hyperkalaemia; however, when this compensation is incomplete, hyperkalaemia occurs.

Secretion of unconjugated estrone during pregnancy and around parturition in goats

The secretion of unconjugated estrone and its production site in pregnant goats were investigated in vivo. The mean estrone concentration (n = 15) in the peripheral plasma increased gradually, being 83 pg/ml on Day 40 and 483 pg/ml on Day 140 after mating. The estrone concentration increased rapidly after Day 2 before partum, reaching a peak at parturition (2370 pg/ml), and falling to 171 pg/ml at Day 1 post partum. The concentrations of estrone from the umbilical vein and umbilical artery did not differ from that found in the maternal jugular vein, suggesting that the fetus does not take part in estrogen production. The estrone concentration from the uterine vein after the fetus was removed was higher than the concentrations found in the maternal jugular vein and umbilical artery. In the placental tissue, a high concentration of estrone (18157 pg per gram of wet tissue) was detected. These findings suggest that the main production site of unconjugated estrone is the placenta.

Double cancer in different hepatic lobes: hepatocellular and cholangiocellular carcinoma

BACKGROUND/AIM

Hepatic tumors with elements of both hepatocellular and cholangiocellular carcinoma are occasionally encountered; however, the independent and simultaneous occurrence of different epithelial malignant tumors in different lobes is rare. This is a case report of resected double cancer in different lobes of the liver.

MATERIALS AND METHODS

A 73 year old Japanese man, with hepatic mass and a history of peritonitis and hepatitis, underwent laparotomy and hepatic resection of the posterior inferior and the left lateral segment, and cholecystectomy for cholecystlithiasis with left-sided gallbladder at our hospital in 1991.

RESULTS

The tumor, located in the posterior inferior segment, a yellow-white, round, highly circumscribed mass with a thick capsule, was about 9.0 by 8.0 cm in size. The other tumor located in the left lateral segment, grayish-white on the cut section, was approximately 5.0 by 4.0 cm.

CONCLUSION

In our case, it is unlikely the tumor in the right lobe metastasized to the left lobe and transformed into a different type. The two tumors showed clearly different microscopic features. Improved imaging will increase the frequency and number of double cancer diagnosis. This additional data may shed light on the pathogenesis and etiology of double cancer.

Differential expression of Fas antigen and Bcl-2 protein on CD4+ T cells, CD8+ T cells, and monocytes

Fas antigen and Bcl-2 protein are considered to be involved in cellular homeostasis. We precisely analyzed the expression of human Fas antigen and Bcl-2 protein on CD4+ T cells, CD8+ T cells, and monocytes. The positivities of Fas antigen on CD4+ and CD8+ T cells increased with aging. In CD4+ T cells, the Fas-/CD45RO+ subpopulation was dominant compared with the Fas+/CD45RO- subpopulation. Conversely, in CD8+ T cells, the Fas+/CD45RO- subpopulation was dominant compared with the Fas-/CD45RO+ subpopulation. Monocytes exhibited high positivity of Fas antigen and low fluorescence intensity of Bcl-2 protein compared with T cells. These results suggest that Fas antigen acts in different processes of cellular homeostasis between CD4+ and CD8+ T cells and that expression of Fas antigen and Bcl-2 protein is involved in homeostasis of monocytes as well as lymphocytes.

Establishment of novel lymphoid cell lines dually infected with human T cell lymphotropic viruses types I and II

With the goal of establishing an in vitro system of dual infection with human T cell lymphotropic viruses (HTLV) types I and II, rabbit lymphocytes were cocultured with a mixture of lethally irradiated HTLV-I-producing Ra-1 and HTLV-II-producing RII cell lines. This gave rise to a lymphoid cell line, RW-1, that was dually infected with HTLV-I and -II as detected by immunofluorescence staining, electron microscopy, and polymerase chain reaction using primers specific for the pol and env regions of each virus and by Southern blot hybridization. Two clonal cell lines derived from RW-1 were also coinfected with the viruses, indicating that dual infection had occurred at the single cell level. The coinfection could be readily propagated to fresh lymphocytes by coculture with RW-1. In contrast, attempts to superinfect HTLV-I-infected lymphoid cell lines with HTLV-II and vice versa were consistently unsuccessful, suggesting receptor interference between HTLV-I and -II.

Inhibition of MAP kinase kinase blocks the differentiation of PC-12 cells induced by nerve growth factor

The mitogen-activated protein kinase (MAP kinase) pathway is thought to play an important role in the actions of neurotrophins. A small molecule inhibitor of the upstream kinase activator of MAP kinase, MAP kinase kinase (MEK) was examined for its effect on the cellular action of nerve growth factor (NGF) in PC-12 pheochromocytoma cells. PD98059 selectively blocks the activity of MEK, inhibiting both the phosphorylation and activation of MAP kinases in vitro. Pretreatment of PC-12 cells with the compound completely blocked the 4-fold increase in MAP kinase activity produced by NGF. Half-maximal inhibition was observed at 2 microM PD98059, with maximal effects at 10-100 microM. The tyrosine phosphorylation of immunoprecipitated MAP kinase was also completely blocked by the compound. In contrast, the compound was without effect on NGF-dependent tyrosine phosphorylation of the pp140trk receptor or its substrate Shc and did not block NGF-dependent activation of phosphatidylinositol 3'-kinase. However, PD98059 completely blocked NGF-induced neurite formation in these cells without altering cell viability. These data indicate that the MAP kinase pathway is absolutely required for NGF-induced neuronal differentiation in PC-12 cells.

Microvessel quantitation in invasive breast cancer by staining for factor VIII-related antigen

The clinical importance of microvessel quantitation as a prognostic indicator in invasive breast cancer was examined. This study included 155 patients with invasive breast cancer, with a median follow-up of 82 months. Microvessels were identified by immunohistochemical staining for factor VIII-related antigen in formalin-fixed, paraffin-embedded primary tumours. For each tumour, microvessels were counted within a 200 x magnification field in the area of highest microvessel density. Microvessel counts (MVCs) had no correlation with tumour size, lymph node status or histological grade. When patients were classified by MVC, higher counts were associated with shorter disease-free survival and overall survival (P < 0.025 and P < 0.01 respectively). Multivariate analysis showed that MCV is an independent prognostic factor. Microvessel quantitation may be a useful predictor for identifying breast cancer patients at high risk for relapse and death.

High glucose increases platelet-derived growth factor production in cultured human vascular endothelial cells and preventive effects of eicosapentaenoic acids

The regulation of the production of platelet-derived growth factor (PDGF) and the influence of high glucose concentration, eicosapentaenoic acid (EPA) were studied in cultured human umbilical vein endothelial cells (HUE). The PDGF production of HUE increased markedly depending on glucose concentration. However, EPA (3 x 10(-4)M) markedly inhibited PDGF production [27.5 mM glucose group: 123 +/- 3% of control (5.5 mM glucose group), 27.5 mM glucose+EPA group: 104 +/- 5% of control]. These results suggested that a high glucose concentration and a high osmotic pressure-induced increase in PDGF production is involved in the development and progression of diabetic macroangiopathy. As eicosapentaenoic acid inhibits the PDGF production induced by high glucose concentration in HUE, use of this agent may exhibit anti-arteriosclerotic effects.

Effects of hypercapnia on ECoG and oxidative metabolism in neonatal dog brain

The effects of hypercapnia on cerebral electrical activity and mitochondrial oxidative phosphorylation were studied in the anesthetized neonatal dog by using the electrocorticogram (ECoG) and 31P-magnetic resonance spectroscopy. Three levels of hypercapnia with arterial PCO2 values of approximately 70, 100, and 140 Torr reduced the intracellular pH of the brain from 7.11 to 6.99, 6.87, and 6.76, respectively. These levels of hypercapnia also reduced ADP concentration ([ADP]) from 21.5 to 18.1, 14.8, and 12.9 microM as well as the average ECoG power output by 20, 30, and 40%. A Michaelis-Menten relationship for the mitochondrial respiratory enzymes was fitted with [ADP] and the change in the average ECoG. The result suggests that mitochondrial respiration is regulated by [ADP] and that the in vivo Michaelis-Menten constant for ADP was 21 microM, a value close to the in vitro value. The mitochondrial maximal reaction velocity was reduced by only 10% during hypercapnia and showed no relationship with the degree of acidosis, suggesting that mitochondrial respiratory enzymes are not responsible for the inhibition of the brain electrical activity.

[Role of carbohydrate antigens in cell-cell and cell to extracellular matrix adhesion on pancreatic cancer]

We investigated the variable adhesiveness of pancreatic cancer cells by glycosylation inhibitor to elucidate the role of carbohydrate antigens in cell-cell and cell to extracellular matrix adhesion. Various carbohydrate antigens were strongly expressed on pancreatic cancer cell (SW1990) by ELISA, and these expression correlated to its in vitro invasiveness and in vivo metastatic potential. Cellular adhesion to Matrigel, laminin and collagen type IV and homotypic cellular aggregation in SW1990 were enhanced by reducing O-linked glycosylation with its inhibitor (Bzl-GalNAc), and these effect were reversed by additional purified mucins. These results suggested that O-linked glycoproteins on SW1990 cell surface may inhibit its adhesiveness to the substratum and aggregation properties by hindering surface receptors, and this variability of adhesiveness induced by altered glycosylation may have an another important role in highly metastatic potential of well glycosylated cancer cells.

Restoration of myo-inositol uptake by eicosapentaenoic acid in human skin fibroblasts cultured in high-glucose medium

The effects of elevated glucose and eicosapentaenoic acid (EPA, C20:5 omega 3) on myo-inositol uptake in human skin fibroblasts (HSF) were evaluated. Myo-inositol incorporation into HSF was dependent on an active transport system via Na(+)-K+ ATPase activity based on the results with Na+ deprivation and ouabain (5 mM). Although glucose (27.5, 55 mM) inhibited 2-[3H] myo-inositol uptake, the addition of EPA (3 x 10(-4) M) prevented glucose-mediated inhibition. Since EPA decreased glucose-mediated inhibition of myo-inositol uptake, this agent might ameliorate some of the devastating functions associated with diabetes.

[Triple primary intracranial tumors of different cell types: a case report]

We report a case of triple intracranial tumors of different cell types without phacomatosis. The patient was a 77-year-old female who was hospitalized with left hemiparesis and vomiting. Computed tomography (CT) scans revealed a large tumor mass in the right frontal lobe and relatively small tumor masses in the medial right frontal and parietal lobes. Other tumors were also detected in the sella turcica, left sphenoidal wing, left anterior clinoidal process and left cerebellar convexity. This case was considered to be one of metastatic brain tumors, and surgery was performed for the right frontal tumor because of its mass effect. The tumor was so highly vascular that it could not be totally removed. Postoperatively, the mass effect showed a gradual increase on CT scans because of intratumoral hemorrhage and peritumoral edema. The patient's consciousness level gradually fell, and she died of pneumonia and cardiac insufficiency 1 month after the operation. The surgical specimen of the tumor was diagnosed as glioblastoma multiforme by histological examination. At autopsy, the small tumors in the medial frontal lobe and parietal lobe were found to be clearly separated from the large right frontal tumor and were diagnosed as multicentric glioblastoma multiforme. The sellar tumor revealed chromophobe pituitary adenoma and was diagnosed as a prolactinoma by immunohistochemical examination. The tumors in the left sphenoidal wing and left cerebellar convexity were diagnosed as transitional meningiomas. Multiple primary intracranial tumors of different cell types without phacomatosis are relatively rare, but almost 100 reported cases could be found in the literature.(ABSTRACT TRUNCATED AT 250 WORDS)

[The changes in nuclear DNA content in acquisition of a high capacity for metastasis of human cell lines]

Quantification of nuclear DNA content in cancer is considered a prognostic factor, and several investigators have demonstrated that aneuploid tumors are more aggressive than diploid tumors. In this report, we investigated the relationship between metastatic capacity and nuclear DNA content using gastric and colon cancer cell lines. We established a highly peritoneal metastatic cell line (2M-D3) from a gastric cancer cell line (2M) and a highly liver metastatic cell line (LM-H3) from colon cancer cell line (LM) in our laboratory. Both the highly metastatic cell lines have more capacity for growth and metastasis, but lower nuclear DNA content and chromosome numbers than these parental cell lines. The results indicated that metastatic capacity was inversely proportional to nuclear DNA content. We cannot provide a satisfactory explanation for this inverse correlation between metastatic capacity and nuclear DNA content, but it is supposed that each cancer cell may have suitable and stable nuclear DNA content in metastasis.

Role of SPan-1 antigen in adhesion of human colon cancer cells to vascular endothelium

Recently E-selectin (ELAM-1, endothelial leukocyte adhesion molecule-1) was shown to recognize not only sialyl Lewis X but also sialyl Lewis A, and these carbohydrate antigens may be involved in the process of the adhesion between cancer cells and endothelial cells in cancer metastasis. To investigate the contribution of sialylated carbohydrate antigen, SPan-1, and sialic acid to the adhesion of human colon cancer cells to endothelial cells, adhesion assay using HUVECs (human umbilical vein endothelial cells) was performed. The adhesion was significantly inhibited by pretreatment with anti-E-selectin antibody, indicating that this adhesion was thought to be mediated by E-selectin. When these cancer cells were pretreated with SPan-1 antibody, the adhesion was significantly inhibited in a concentration-dependent manner. The adhesion was also inhibited by pretreatment with neuraminidase. These findings suggest that the SPan-1 antigen plays a significant role in the adhesion of human colon cancer cells to endothelial cells, and sialylation of the terminal structure of carbohydrate antigens is important in this adhesion.

Laparoscopic-assisted colectomy and lymphadenectomy without peritoneal insufflation for sigmoid colon cancer patients

PURPOSE

A new method for laparoscopic-assisted sigmoid colectomy and lymphadenectomy is presented. The purpose of this method is to avoid complications and restrictions associated with pneumoperitoneum.

METHODS

Abdominal wall is lifted up with Kirschner wires, which are placed in the middle and left lower abdomen; then a minilaparotomy, which can be created because air-tightness is not necessary, is extended at the beginning of the operation to later remove the resected specimen. Two laparoscopic instruments are inserted through the right lower abdomen. Through the minilaparotomy, the surgeon can operate with conventional instruments.

RESULTS

Operative time can be shortened, and surgical manipulations such as ligations and sutures are far easier than and cosmetic results are similar to those of laparoscopic surgery under pneumoperitoneum.

CONCLUSION

We believe that this technique is a safe, time-saving, and cost-beneficial technique for sigmoid colectomy, and by changing the location of the minilaparotomy, this method can also be applied to other types of gastrointestinal surgery.

[Immunohistochemical study of proliferation index of astrocytomas classified by new histopathological grading]

A new grading method of astrocytoma, proposed by Daumas-Duport et al, was based on four criteria:nuclear atypia, mitosis, necrosis and endothelial proliferation (0 criteria = Grade 1, 1 criteria = Grade 2, 2 criteria = Grade 3, 3 or 4 criteria = Grade 4). To elucidate the correlation of the classification based on four criteria, cellularity and proliferative activities, we studied proliferating index of 67 astrocytomas, using immunohistochemical staining for Ki-67 antibodies (MIB-1). A new grading method was related to proliferating index in this study, however, cellularity of tumor cells was not related to proliferating index. In this study, endothelial proliferation was invariably seen in high grade(Grade 3 and 4) astrocytomas. These tumor vessels were associated with dysfunction of blood-brain barrier and some growth factors accelerated to tumor cell proliferation. Relation between histopathological grade of astrocytoma and proliferation index was supposed, and new grading system was thought to be useful for routine pathological examination.

High-performance frontal analysis for the study of protein binding of troglitazone (CS-045) in albumin solution and in human plasma

An on-line frontal analysis HPLC system was developed for the determination of the unbound concentration of troglitazone (CS-045), a new oral antidiabetic agent, in human serum albumin (HSA) solution and in human plasma. This system consists of a high-performance frontal analysis (HPFA) column, an extraction column, and an analytical column, which are connected via two switching valves. After the direct injection of the sample solution into the HPFA column, the drug was eluted as a zonal peak with a plateau region. The unbound drug concentration was determined as the drug concentration in the plateau. As low as 0.3 nM unbound CS-045 was determined with good reproducibility. It was found that CS-045 strongly binds with HSA, and the bound fraction in the 550 microM HSA solution was 99.93%, which was very close to that in human plasma (99.89%). The bound fractions were constant within the total drug concentration range of 1-10 microM in the HSA solution and 250 nM-10 microM in human plasma.

[Malignancy of gastric cancer analyzed by the expression of thymidine phosphorylase]

In this study, the expression of thymidine phophorylase (dThdPase) was investigated immunohistochemically in 73 patients with gastric cancer. dThd Pase was mainly distributed at the apical portion, or cytoplasm of cancer cells and its expression was detected in 52 tumors (71.2%). There were no significant association among the expression of dThdPase, histologic type, depth of invasion, and lymph node metastasis. However, a significant difference was noted with respect to liver metastases. Among 73 patients, liver metastases were observed in 11 patients. dThdPase expression was detected in all of these cases with liver metastases, which was significantly more common than those without such metastases. In relation to the prognosis, patients with dThdPase-positive tumors had a significantly worse prognosis than those with dThdPase-negative tumors. In conclusion, the expression of dThdPase may be useful as a predictor of malignant potential in gastric cancer.

Age-related profile of neuroblastoma: a comparison of tumors detected by mass-screening with those detected clinically

Infants with neuroblastoma are known to have a favorable prognosis compared to those over 1 year of age. However, there is little biological information about the age-related heterogeneity of neuroblastoma. We evaluated the biological profile comparing cases detected by mass screening with those detected clinically. A total of 238 patients with neuroblastoma were classified into four groups according to their age at diagnosis. Patients in group A were 0-5 months of age (n = 31). Patients in group B were detected clinically and were 6-11 months of age (n = 25). Patients in group C were 6-11 months of age and were detected by mass-screening (n = 97). Patients in group D were more than 12 months of age (n = 85). The age-related heterogeneity was evaluated by Kaplan-Meier survival analysis, several clinical markers (neuron specific enolase, ferritin, vanillylmandelic acid and homovanillic acid) at diagnosis, tumor Ha-ras p21 expression and tumor N-myc amplification. Infant neuroblastoma had unique features in comparison to neuroblastoma diagnosed over 12 months of age. Clinical outcome of the patients in groups A and C was quite favorable. Even patients with stage III or IV disease in group A had a favorable prognosis. However, stage IVs disease in group A was not necessarily associated with a good prognosis and the early death after diagnosis was also characteristic. The biological profile of tumors in group C was similar to that in group A but different from the profile in groups B and D. Tumors in group B had a biological profile intermediate between groups A and D.(ABSTRACT TRUNCATED AT 250 WORDS)

[Clinical significance of argyrophilic nucleolar organizer regions (AgNOR) and microvessel quantitation by staining for factor VIII-related antigen as prognostic indicators in stage I breast cancer]

The clinical significance of AgNOR and microvessel quantitation as prognostic indicators in Stage I breast cancer were examined. This study included 99 patients with Stage I breast cancer, with a median follow-up period of 119 months. AgNOR was stained by Crocker's method and microvessels were identified by immunohistochemical staining for Factor VIII-related antigen in formalin-fixed, paraffin-embedded primary tumors. AgNOR score related with tumor size. Microvessel count was related to estrogen receptor status. When patients were classified into two groups by the mean AgNOR score, higher scores had a tendency to be correlated with shorter overall survival. And when classified by microvessel count, higher counts were significantly associated with shorter overall, survival (p < 0.01). The microvessel count might be a useful predictor and the AgNOR score could be used to corroborate predictions for identifying patients at high risk for relapse and death in Stage I breast cancer.

Characterization and biodistribution of a mouse/human chimeric antibody directed against pancreatic cancer mucin

BACKGROUND

Nd2 is a murine monoclonal antibody (MoAb) directed against purified mucins of the human pancreatic cancer cell line SW1990. The authors previously reported promising results with Nd2 for immunotargeting pancreatic cancer. However, murine MoAbs induce human anti-mouse antibodies (HAMAs), a serious problem for clinical use. Mouse/human chimeric antibodies may be less immunogenic and therefore reduce the incidence of HAMAs. In this study, the binding affinity, tumor specificity, biodistribution, and immunoimaging of chimeric Nd2 were evaluated.

METHODS

The affinity of chimeric Nd2 was evaluated by competition radioimmunoassay and Scatchard analysis using 125I-chimeric Nd2, 125I-murine Nd2, and SW1990 mucin. Immunoreactivity against pancreatic cancer tissues was examined histochemically by the avidin-biotin peroxidase complex method. The biodistribution of the MoAbs was examined in athymic nude mice bearing SW1990 xenografts that were administered intravenous 125I-labeled chimeric or murine Nd2. 111In-chimeric Nd2 was injected into the same xenograft models, and scintigrams were obtained on day 3.

RESULTS

Affinity analysis and immunohistochemical studies showed that chimeric Nd2 had the same affinity to SW1990 mucin and the same specificity for pancreas cancer tissues as murine Nd2. Intravenous administration of 125I-chimeric Nd2 resulted in a maximum tumor accumulation of 43% of the initial dose/gram of tumor, which was almost identical to the accumulation of 125I-murine Nd2. Distinct immunoscintigrams of tumors in nude mice were obtained with 111In-chimeric Nd2.

CONCLUSION

Chimeric Nd2 may have clinical potential in the radioimmunodetection and immunotherapy of pancreatic cancer.

Polypoid growth and K-ras codon 12 mutation in colorectal cancer

BACKGROUND

To clarify genetic changes in colorectal tumorigenesis, K-ras codon 12 point mutations were examined in 101 ordinary colorectal carcinomas and 6 that complicated ulcerative colitis (UC) with special attention to growth patterns.

METHODS

The depths of invasion of ordinary carcinoma were submucosa (SMCa) in 39 cases, muscularis propria (PMCa) in 33, and far-advanced in 29. Growth patterns of SMCa and PMCa were classified into three types: polypoid-growth type without central depression (Type 1), polypoid-growth type with central depression (Type 2), and nonpolypoid-growth type. DNA samples were extracted from formalin fixed paraffin embedded sections, and K-ras codon 12 mutations were examined by two-step polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

K-ras mutation frequency was higher in Type 1 SMCa than in nonpolypoid SMCa, 56% (9/16) versus 6% (1/17), respectively, and in PMCa, 78% (7/9) versus 23% (3/13), respectively. In 6 UC carcinomas, a K-ras mutation was detected in only one polypoid carcinoma and none were detected in five nonpolypoid carcinomas.

CONCLUSIONS

These results and the authors' previous study suggest that nonpolypoid carcinomas may be derived from flat adenomas, whose K-ras mutation incidence also was low, and this pathway is different from a genetic model based on the ordinary adenoma-carcinoma sequence through polypoid adenomas.